阅读说明：本技术 穿孔机、芯棒、以及使用了它们的无缝金属管的制造方法 (Piercing machine, mandrel bar, and method for producing seamless metal pipe using same ) 是由 大部晴佳 坂本明洋 大门靖彦 于 2018-11-28 设计创作，主要内容包括：提供一种能够抑制穿孔轧制后或延伸轧制后的空心管坯的前端部与后端部的温度差的穿孔机。穿孔机的芯棒(3)包括：棒主体(31)；冷却液流路(34),其形成于棒主体(31)内,供冷却液流动；内表面冷却机构(340),其配置于冷却区域(32),与冷却液流路(34)相连,在穿孔轧制时或延伸轧制时,向棒主体(31)的外部喷射冷却液而冷却冷却区域(32)内的空心管坯(50)的内表面部分；以及内表面拦截机构(350),其以与冷却区域(32)相邻的方式配置于冷却区域(32)的后方,在穿孔轧制或延伸轧制时,抑制被喷射到棒主体(31)的外部的冷却液与位于冷却区域(32)的后方的空心管坯(50)的内表面部分接触。(Provided is a piercing mill capable of suppressing a temperature difference between a front end portion and a rear end portion of a hollow shell after piercing-rolling or elongating. A plug (3) of a piercing machine comprises: a rod main body (31); a coolant flow path (34) formed in the rod main body (31) and through which coolant flows; an inner surface cooling means (340) which is disposed in the cooling region (32), is connected to the coolant flow path (34), and sprays coolant to the outside of the rod main body (31) during piercing rolling or elongation rolling to cool the inner surface portion of the hollow shell (50) in the cooling region (32); and an inner surface intercepting means (350) which is disposed behind the cooling zone (32) so as to be adjacent to the cooling zone (32) and which suppresses the coolant, which is injected to the outside of the rod main body (31), from coming into contact with the inner surface portion of the hollow shell (50) located behind the cooling zone (32) during piercing-rolling or elongating.)

1. A piercing mill for producing a hollow shell by piercing-rolling or elongating a raw material,

the piercing machine includes:

a plurality of inclined rolls disposed around a pass line through which the material passes;

a plug disposed on the pass line between the plurality of inclined rolls; and

a plug extending rearward of the plug from a rear end of the plug along the rolling line,

the mandrel comprises:

a rod body;

a coolant flow path formed in the rod main body, the coolant flowing through the coolant flow path;

an inner surface cooling mechanism which is disposed in a cooling zone of the rod main body, the cooling zone having a specific length in the axial direction of the mandrel bar and being located at a tip end portion of the mandrel bar, and which, during piercing rolling or elongation rolling, sprays the cooling liquid supplied from the cooling liquid flow passage to the outside of the rod main body to cool an inner surface of the hollow shell during travel in the cooling zone; and

and an inner surface intercepting means which is disposed at the rear of the cooling zone so as to be adjacent to the cooling zone, and which suppresses the coolant, which is injected to the outside of the rod main body, from coming into contact with the inner surface of the hollow shell after the coolant has exited from the cooling zone during piercing rolling or elongating rolling.

2. The perforator of claim 1,

the inner surface intercepting means intercepts the coolant injected to the outside of the rod main body, and accumulates the coolant between the rod main body and the inner surface of the hollow shell in the cooling region.

3. The piercing machine according to claim 1 or 2,

the mandrel further includes a compressed gas flow path formed in the mandrel body for passing a compressed gas therethrough,

in the piercing rolling or the elongating rolling, the inner surface intercepting means injects the compressed gas supplied from the compressed gas flow path to the outside of the rod main body, thereby suppressing the coolant injected to the outside of the rod main body from coming into contact with the inner surface of the hollow shell after coming out of the cooling zone.

4. The perforator of claim 3, wherein,

the inner surface intercepting means intercepts the coolant injected to the outside of the rod main body by the compressed gas injected to the outside of the rod main body, and accumulates the coolant between the rod main body and the inner surface of the hollow shell in the cooling region.

5. The piercing machine according to claim 1 or 2,

the inner surface intercepting means includes an inner surface intercepting member disposed behind the cooling region so as to be adjacent to the cooling region, extending in a circumferential direction of the rod main body,

the height of the inner surface intercepting member is lower than the difference between the maximum radius of the head and the radius of the rod main body at the position where the inner surface intercepting member is disposed.

6. The perforator of claim 5, wherein,

the inner surface intercepting means intercepts the coolant injected to the outside of the rod main body by the inner surface intercepting member, and causes the coolant to be accumulated between the rod main body and the inner surface of the hollow shell in the cooling region.

7. The piercing machine according to any one of claims 1 to 6,

the mandrel further comprises:

a liquid discharge flow path formed in the rod main body, through which the coolant ejected to the outside of the rod main body flows; and

and 1 or more drain holes which are disposed in the cooling region of the rod main body, are connected to the drain flow path, and collect the coolant sprayed to the outside of the rod main body.

8. The piercing machine according to any one of claims 1 to 7,

the inner surface cooling mechanism includes a plurality of coolant ejection holes arranged in the circumferential direction of the rod body or arranged in the circumferential direction and the axial direction of the rod body in the cooling region for ejecting the coolant.

9. The perforator of claim 8,

a plurality of the coolant ejection holes are directed in the circumferential direction of the rod body as viewed in the traveling direction of the hollow shell,

the inner surface cooling mechanism sprays the cooling liquid from the plurality of cooling liquid spraying holes along the circumferential direction of the rod body, thereby revolving the cooling liquid in the cooling region around the rod body.

10. The perforator of claim 9,

a plurality of the coolant ejection holes are directed toward the circumference of the rod body and rearward of the rod body,

the inner surface cooling mechanism sprays the coolant from the plurality of coolant spray holes toward the circumferential direction of the rod main body and the rear side of the rod main body, thereby revolving the coolant in the cooling region around the rod main body.

11. The piercing machine according to claim 3 or 4,

the inner surface cooling mechanism includes a plurality of coolant ejection holes arranged in a circumferential direction of the rod body or in a circumferential direction and an axial direction of the rod body in the cooling region for ejecting the coolant,

the inner surface intercepting means includes a plurality of compressed gas injection holes arranged in a circumferential direction of the rod main body or in a circumferential direction and an axial direction of the rod main body, in a contact suppression region disposed rearward of the cooling region so as to be adjacent to the cooling region, for injecting the compressed gas.

12. The perforator of claim 11,

the plurality of compressed gas injection holes are directed in the circumferential direction of the rod main body as viewed in the traveling direction of the hollow shell,

the inner surface intercepting means ejects the compressed gas from the compressed gas ejection hole along a circumferential direction of the rod main body, thereby revolving the compressed gas within the contact suppression area around the rod main body.

13. The perforator of claim 12,

the plurality of compressed gas injection holes are directed toward the circumferential direction of the rod main body and rearward of the rod main body,

the inner surface intercepting means injects the compressed gas from the compressed gas injection hole toward the circumferential direction of the rod main body and the rear of the rod main body, thereby revolving the compressed gas in the contact suppressing area around the rod main body.

14. The perforator of claim 13,

the direction of rotation of the coolant ejected from the plurality of coolant ejection holes is right-handed or left-handed as viewed in the direction of travel of the hollow shell,

the direction of rotation of the compressed gas injected from the plurality of compressed gas injection holes is right-handed or left-handed as viewed in the direction of travel of the hollow shell,

the inner surface intercepting means ejects the compressed gas in such a manner that a revolution direction of the compressed gas is the same as a revolution direction of the cooling liquid.

15. The piercing machine according to any one of claims 12 to 14,

the inner surface cooling means includes a plurality of annularly arranged cooling liquid injection hole groups arranged in an axial direction of the rod main body in the cooling region of the rod main body,

the annularly arranged group of cooling liquid injection holes includes a plurality of the cooling liquid injection holes arranged in the circumferential direction at the same position in the axial direction of the rod body,

with respect to the inner surface cooling mechanism,

when an axial distance of the rod body, at which the swirl flow of the coolant advances to make one revolution around the rod body, is defined as 1-revolution period distance, a distance between the adjacent annularly-arranged coolant injection hole groups in the axial direction of the rod body is the same as the 1-revolution period distance.

16. The piercing machine according to any one of claims 1 to 15,

the piercing machine further includes an outer surface cooling mechanism disposed around the mandrel bar behind the plug,

the outer surface cooling mechanism sprays a cooling fluid toward an upper portion of the outer surface, a lower portion of the outer surface, a left portion of the outer surface, and a right portion of the outer surface of the hollow shell during travel in the cooling zone as viewed in a travel direction of the hollow shell to cool the hollow shell in the cooling zone.

17. The perforator of claim 16,

the exterior surface cooling mechanism includes:

an outer surface cooling upper member that is disposed above the plug as viewed in a traveling direction of the hollow shell, and includes a plurality of cooling fluid upper injection holes that inject the cooling fluid toward an upper portion of the outer surface of the hollow shell in the cooling zone;

an outer surface cooling lower member that is disposed below the plug as viewed in a traveling direction of the hollow shell, and that includes a plurality of cooling fluid lower ejection holes that eject the cooling fluid toward a lower portion of the outer surface of the hollow shell in the cooling zone;

an outer surface cooling left member that is disposed on the left side of the plug as viewed in the traveling direction of the hollow shell, and that includes a plurality of cooling fluid left spray holes that spray the cooling fluid toward the left portion of the outer surface of the hollow shell in the cooling zone; and

and an outer surface cooling right member which is disposed rightward of the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of cooling fluid right spray holes for spraying the cooling fluid toward a right portion of the outer surface of the hollow shell in the cooling zone.

18. The perforating machine as recited in claim 16 or 17,

the piercing machine further includes a front intercepting means disposed behind the plug and around the mandrel bar in front of the outer surface cooling means,

the front interception mechanism comprises the following mechanisms: when the outer surface cooling means sprays the cooling fluid toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell to cool the hollow shell in the cooling region, the means blocks the flow of the cooling fluid toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell before entering the cooling region.

19. The perforator of claim 18,

the front interception mechanism comprises:

a front intercepting upper member that is disposed above the plug as viewed in a traveling direction of the hollow shell, and includes a plurality of front intercepting fluid upper injection holes that inject a front intercepting fluid toward an upper portion of the outer surface of the hollow shell located in a vicinity of an entrance side of the cooling zone to intercept a flow of the cooling fluid toward the upper portion of the outer surface of the hollow shell before entering the cooling zone;

a front intercepting left member which is disposed on a left side of the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid lower injection holes that inject the front intercepting fluid toward a left portion of the outer surface of the hollow shell located in a vicinity of an entrance side of the cooling zone and intercept a flow of the cooling fluid toward the left portion of the outer surface of the hollow shell before entering the cooling zone; and

and a front intercepting right member which is disposed on the right side of the plug as viewed in the traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid right injection holes that inject the front intercepting fluid toward the right portion of the outer surface of the hollow shell located in the vicinity of the entrance side of the cooling zone and intercept the flow of the cooling fluid toward the right portion of the outer surface of the hollow shell before entering the cooling zone.

20. The perforator of claim 19,

the front intercepting upper member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid upper jet holes toward an upper portion of the outer surface of the hollow shell located in the vicinity of an entry side of the cooling zone,

the front intercepting left member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid left jet holes toward a left portion of the outer surface of the hollow shell located in the vicinity of an entry side of the cooling zone,

the front intercepting right member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid right jet holes toward a right portion of the outer surface of the hollow shell located in the vicinity of an entry side of the cooling zone.

21. The perforating machine as claimed in claim 19 or 20,

the front intercepting means further includes a front intercepting member disposed below the plug as viewed in a traveling direction of the hollow shell, the front intercepting member including a plurality of front intercepting fluid lower injection holes that inject the front intercepting fluid toward a lower portion of the outer surface of the hollow shell located near an entrance side of the cooling zone and intercept a flow of the cooling fluid toward the lower portion of the outer surface of the hollow shell before entering the cooling zone.

22. The perforator of claim 21,

the front intercepting lower member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid lower jet holes toward a lower portion of the outer surface of the hollow shell located in the vicinity of an entry side of the cooling zone.

23. The piercing machine according to any one of claims 16 to 22,

the piercing machine further includes a rear catching mechanism disposed around the mandrel bar behind the outer surface cooling mechanism,

the rear interception mechanism comprises the following mechanisms: when the outer surface cooling means sprays the cooling fluid toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell to cool the hollow shell, the means blocks the cooling fluid from flowing to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell after exiting from the cooling region.

24. The perforator of claim 23,

the rear interception mechanism includes:

a rear intercepting upper member which is disposed above the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of rear intercepting fluid upper injection holes that inject a rear intercepting fluid toward an upper portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone to intercept a flow of the cooling fluid toward the upper portion of the outer surface of the hollow shell after the exit from the cooling zone;

a left rear intercepting member which is disposed on a left side of the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of left rear intercepting fluid ejecting holes that eject the left rear intercepting fluid toward a left portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone and intercept a flow of the cooling fluid toward a left portion of the outer surface of the hollow shell after the exit from the cooling zone; and

and a rear intercepting right member which is disposed on a right side of the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of rear intercepting fluid right injection holes that inject the rear intercepting fluid toward a right portion of the outer surface of the hollow shell located in a vicinity of an exit side of the cooling zone and intercept a flow of the cooling fluid toward the right portion of the outer surface of the hollow shell after the exit from the cooling zone.

25. The perforator of claim 24,

the upper rearward intercepting member injects the rearward intercepting fluid obliquely forward from the plurality of rearward intercepting fluid upper injecting holes toward an upper portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone,

the backward intercepting left member jets the backward intercepting fluid diagonally forward from the plurality of backward intercepting fluid left jet holes toward a left portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone,

the right backward intercepting member injects the backward intercepting fluid obliquely forward from the plurality of right backward intercepting fluid injection holes toward a right portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone.

26. The perforating machine as recited in claim 24 or 25,

the rearward intercepting means further includes a rearward intercepting member which is disposed below the plug as viewed in a traveling direction of the hollow shell, and which includes a plurality of rearward intercepting fluid lower ejecting holes that eject the rearward intercepting fluid toward a lower portion of the outer surface of the hollow shell located in the vicinity of a discharge side of the cooling zone to intercept a flow of the cooling fluid toward the lower portion of the outer surface of the hollow shell after the hollow shell has discharged from the cooling zone.

27. The perforator of claim 26,

the back damming member sprays the back damming fluid obliquely forward from the plurality of back damming fluid lower spray holes toward a lower portion of the outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone.

28. A mandrel bar according to any one of claims 1 to 27.

29. A method for producing a seamless metal pipe using the piercing machine according to any one of claims 1 to 27, wherein,

the method for manufacturing the seamless metal tube comprises the following steps:

a rolling step of producing a hollow shell by piercing-rolling or elongating the material by using the piercing mill;

in the rolling step, the coolant is sprayed to the outside of the rod main body by the inner surface cooling means to cool the inner surface of the hollow shell in the cooling zone, and the coolant sprayed to the outside of the rod main body is suppressed from contacting the inner surface of the hollow shell after coming out of the cooling zone by an inner surface intercepting means disposed behind the cooling zone so as to be adjacent to the cooling zone.

Technical Field

The present invention relates to a piercing machine, a plug, and a method for manufacturing a seamless metal pipe using the same.

Background

As a method for producing a seamless metal pipe typified by a steel pipe, there is the mannesmann method. In the mannesmann process, a solid round billet is piercing-rolled using a piercing-rolling mill to produce a Hollow Shell (Hollow Shell). Then, the hollow shell produced by piercing-rolling is subjected to elongation rolling so that the hollow shell has a predetermined thickness and a predetermined outer diameter. For example, an elongating mill, a plug mill (plug mill), a mandrel mill (mandril mill), or the like is used for elongating. The hollow shell after the elongating is subjected to sizing rolling using a sizing mill such as a sizer, thereby producing a seamless metal pipe having a desired outer diameter.

The piercing-rolling mill and the elongating mill in the above apparatus for producing a seamless metal pipe have the same configuration. A piercing-rolling mill and an elongation-rolling mill are provided with a plurality of inclined rolls, a plug, and a plug. The plurality of inclined rolls are arranged at equal intervals around a rolling line through which a material (round billet in the case of a piercing-rolling mill, hollow billet in the case of an elongating mill) passes. The plug is positioned between the plurality of inclined rollers and is arranged on the rolling line. The plug has a shell shape, and the outer diameter of the front end of the plug is smaller than the outer diameter of the rear end of the plug. The tip of the plug is disposed opposite the material before piercing-rolling or elongating-rolling. The front end of the mandrel is connected to the central portion of the rear end face of the plug. The plug is disposed on the pass line and extends along the pass line.

The piercing-rolling mill forms a hollow shell by pushing a round billet, which is a raw material, toward a plug while rotating the round billet in the circumferential direction of the round billet by a plurality of inclined rolls, and piercing-rolling the round billet. Similarly, the elongating mill inserts a plug into a hollow shell while rotating the hollow shell as a material in the circumferential direction of the hollow shell by a plurality of inclined rolls, and elongates and rolls the hollow shell by pressing down the hollow shell between the inclined rolls and the plug.

Hereinafter, in the present specification, a rolling apparatus including a plurality of inclined rolls, plugs, and plug bars, such as a piercing mill and a drawing mill, is defined as a "piercing mill". In each configuration of the piercing mill, the entry side of the inclined roll of the piercing mill is defined as "front", and the exit side of the inclined roll of the piercing mill is defined as "rear".

Recently, seamless metal pipes are required to have higher strength. For example, seamless steel pipes used in oil wells and gas wells are required to have high strength as the oil wells and gas wells are made deep. In order to manufacture such a seamless metal pipe having a high strength, for example, quenching and tempering are performed on a hollow shell after piercing rolling and elongating rolling.

If the temperature distribution in the longitudinal direction of the hollow shell before quenching is uneven, the structure becomes uneven in the longitudinal direction in the hollow shell after quenching. If the structure is not uniform in the longitudinal direction, the mechanical properties of the manufactured seamless metal pipe vary in the longitudinal direction. Therefore, it is preferable that the variation in the temperature distribution in the longitudinal direction can be suppressed in the hollow shell after the piercing-rolling or the elongating-rolling using the piercing mill. Specifically, it is preferable to suppress the temperature difference between the front end portion and the rear end portion of the hollow shell after piercing-rolling or elongating.

Techniques for reducing unevenness in temperature distribution of a hollow shell produced by a piercing machine are proposed in japanese patent laid-open nos. 3-99708 (patent document 1) and 2017-13102 (patent document 2).

Patent document 1 describes the following. Patent document 1 aims to reduce the temperature difference between the inner and outer surfaces of a seamless high alloy pipe having a large deformation resistance due to heat generated by working during piercing-rolling or elongation-rolling. In patent document 1, a nozzle hole capable of injecting cooling water obliquely rearward is formed in the rear portion of the plug. During piercing-rolling, cooling water is sprayed from the nozzle hole in the rear of the plug toward the inner surface of the hollow shell being pierced. Thereby, the inner surface heated to a temperature higher than the temperature of the outer surface by heat generated by working is cooled, and the temperature difference between the inner surface and the outer surface of the hollow shell is reduced.

Patent document 2 describes the following. In an elongating mill such as an elongating mill, when a plug is inserted into a hollow shell to perform elongating rolling, the temperature of the plug at the initial stage of elongating rolling is lower than the temperature of the hollow shell. In the elongation rolling, the heat of the hollow shell is transferred to the plug, and the temperature of the plug rises. On the other hand, the temperature of the hollow shell at the initial stage of the elongation rolling is high, but the temperature of the hollow shell gradually decreases due to heat dissipation during the elongation rolling. That is, the temperature of the plug and the temperature of the hollow shell change during the period from the start to the end of the elongating. Therefore, there is a problem that the temperature distribution in the longitudinal direction (axial direction) of the hollow shell after the elongating is uneven (see paragraph [0010] of patent document 2). Therefore, in patent document 2, a plurality of injection holes are provided in the plug rear end surface or the front end portion of the plug. Then, a cooling fluid is blown to the inner surface of the hollow shell during the elongation rolling from the injection hole in the plug rear end surface or the injection hole in the plug tip portion. More specifically, first, the temperature distribution in the axial direction of the hollow shell in the case where the intermediate shell is elongation-rolled without spraying the cooling fluid from the plug rear end surface and the plug front end portion is obtained in advance. Then, based on the obtained temperature distribution, elongation rolling is performed while adjusting the amount of the cooling fluid injected from the injection hole of the plug rear end surface or the plug front end portion. This makes it possible to make the temperature distribution in the axial direction uniform in the hollow shell after the elongation rolling (paragraphs [0020], [0021], and the like).

Disclosure of Invention

Problems to be solved by the invention

In the techniques of patent documents 1 and 2, a cooling fluid is sprayed from a plug or a mandrel toward the inner surface of the hollow shell to cool the inner surface of the hollow shell, thereby cooling the hollow shell. However, in the case where these techniques are applied, there are cases where: a temperature difference is generated between the front end portion of the hollow shell passing through the inclined rolls at the initial stage of rolling and the rear end portion of the hollow shell passing through the inclined rolls at the end of rolling, and it is difficult to make uniform the temperature distribution in the axial direction of the hollow shell after piercing-rolling by the piercing-rolling mill or after elongating-rolling by the elongating-rolling mill.

An object of the present disclosure is to provide a piercing mill capable of suppressing temperature variation in the longitudinal direction (axial direction) of a hollow shell after piercing-rolling or elongating-rolling, a mandrel bar used for the piercing mill, and a method for producing a seamless metal pipe.

Means for solving the problems

The piercing mill of the present disclosure is a piercing mill that performs piercing-rolling or elongation-rolling of a raw material to manufacture a hollow shell, wherein,

the piercing machine includes:

a plurality of inclined rolls disposed around a pass line through which a material passes;

a plug disposed on a pass line between the plurality of inclined rolls; and

a plug extending rearward of the plug along a rolling line from a rear end of the plug,

the core rod includes:

a rod body;

a coolant flow path formed in the rod main body, the coolant flowing through the coolant flow path;

an inner surface cooling mechanism which is disposed in a cooling zone of the rod main body, the cooling zone having a specific length in the axial direction of the mandrel bar and being located at the tip end portion of the mandrel bar, and which, during piercing rolling or elongation rolling, sprays a cooling liquid supplied from the cooling liquid flow path to the outside of the rod main body to cool the inner surface of the hollow shell during travel in the cooling zone; and

and an inner surface intercepting means which is disposed at the rear of the cooling zone so as to be adjacent to the cooling zone, and which suppresses the coolant injected to the outside of the rod main body from coming into contact with the inner surface of the hollow shell after the coolant has exited from the cooling zone during piercing rolling or elongating rolling.

The plug of the present invention is used for the piercing machine.

The method for producing a seamless metal pipe according to the present disclosure is a method for producing a seamless metal pipe using the above piercing machine,

the method for manufacturing the seamless metal tube comprises the following steps:

a rolling step of producing a hollow shell by piercing-rolling or elongating a raw material using a piercing mill; and

in the rolling step, the inner surface of the hollow shell in the cooling zone is cooled by spraying a cooling liquid to the outside of the rod main body by the inner surface cooling means, and the contact between the cooling liquid sprayed to the outside of the rod main body and the inner surface of the hollow shell after coming out of the cooling zone is suppressed by the inner surface intercepting means disposed to the rear of the cooling zone so as to be adjacent to the cooling zone.

ADVANTAGEOUS EFFECTS OF INVENTION

The piercing mill of the present invention can suppress temperature variation in the longitudinal direction (axial direction) of a hollow shell after piercing-rolling or elongating.

Drawings

Fig. 1 is a side view of the piercing machine according to embodiment 1.

Fig. 2 is an enlarged view of a portion near the inclined roller in fig. 1.

Fig. 3 is an enlarged view of a portion near the inclined roller in fig. 1 when viewed from a direction different from that of fig. 2.

Fig. 4 is an enlarged view of the plug 2 and the mandrel 3 in fig. 1.

Fig. 5 is a cross-sectional view (longitudinal sectional view) of the plug 2 and the mandrel 3 shown in fig. 4, including the central axis.

Fig. 6 is a sectional view at line a-a in fig. 5.

Fig. 7 is a sectional view at line B-B in fig. 5.

Fig. 8 is a sectional view at line C-C in fig. 5.

Fig. 9 is a vertical cross-sectional view of the raw material in the vicinity of the inclined rolls in piercing-rolling or elongating in the piercing machine shown in fig. 1.

Fig. 10 is a sectional view at line B-B in fig. 9.

Fig. 11 is a sectional view at line a-a in fig. 9.

Fig. 12 is a vertical cross-sectional view of the material in the vicinity of the inclined rolls in piercing-rolling or elongating in the case where the inner surface intercepting means of the present embodiment is not provided.

Fig. 13 is a sectional view at line C-C in fig. 9.

Fig. 14 is a cross-sectional view of the mandrel bar of fig. 5 taken along line a-a in the piercing machine according to embodiment 2.

Fig. 15 is an enlarged view of the coolant ejection hole in the case where the rod main body of the mandrel shown in fig. 14 is seen from the surface.

Fig. 16 is a cross-sectional view of the mandrel bar of fig. 5 taken along line B-B in the piercing machine according to embodiment 2.

Fig. 17 is an enlarged view of the coolant ejection hole in the case where the rod main body of the mandrel shown in fig. 14 is seen from the surface.

Fig. 18 is a longitudinal sectional view of the piercing mill for explaining the rotational flow of the coolant and the rotational flow of the compressed gas when the piercing-rolling or the elongating is performed on the raw material by the piercing mill according to embodiment 2.

Fig. 19 is a cross-sectional view of the piercing machine for explaining the swirling flow of the coolant and the swirling flow of the compressed gas in the case where the piercing machine according to embodiment 2 is viewed in the axial direction of the rod main body.

Fig. 20 is an enlarged view of the coolant ejection hole in a case where the rod body of the mandrel is viewed from the side, different from fig. 15.

Fig. 21 is a vertical cross-sectional view of the material near the inclined rolls in piercing-rolling or elongating in the piercing mill according to embodiment 3.

Fig. 22 is a vertical cross-sectional view of the material near the inclined rolls in piercing-rolling or elongating in the piercing mill according to embodiment 4.

Fig. 23 is a front view of the outer surface cooling mechanism in fig. 22 as viewed in the traveling direction of the hollow shell.

Fig. 24 is a front view of an external surface cooling mechanism of a different form from fig. 23.

Fig. 25 is a front view of an external surface cooling mechanism of a different form from fig. 22 and 23.

Fig. 26 is a vertical cross-sectional view of the material near the inclined rolls in piercing-rolling or elongating in the piercing machine according to embodiment 5.

Fig. 27 is a front view of the front intercepting means in fig. 26 as viewed in the traveling direction of the hollow shell.

Fig. 28 is a sectional view of the front interception upper member shown in fig. 27, which is parallel to the traveling direction of the hollow shell.

Fig. 29 is a sectional view of the front intercepting member shown in fig. 27, which is parallel to the traveling direction of the hollow shell.

Fig. 30 is a sectional view of the front interception left member shown in fig. 27, parallel to the traveling direction of the hollow shell.

Fig. 31 is a sectional view of the front-intercepting right member shown in fig. 27, parallel to the traveling direction of the hollow shell.

Fig. 32 is a front view of the front intercepting mechanism of a different form from that of fig. 27.

Fig. 33 is a front view of the front intercepting mechanism of a different form from fig. 27 and 32.

Fig. 34 is a front view of the front catching mechanism in a different form from fig. 27, 32, and 33.

Fig. 35 is a front view of the front catching mechanism in a different form from fig. 27 and 32 to 34.

Fig. 36 is a front view of the front catching mechanism in a different form from fig. 27 and 32 to 35.

Fig. 37 is a front view of the front holding mechanism showing a state in which a plurality of holding members in fig. 36 are brought close to the outer surface of the hollow shell in piercing-rolling or elongating-rolling.

Fig. 38 is an enlarged view of the vicinity of the exit side of the inclined roll in the piercing mill according to embodiment 6.

Fig. 39 is a front view of the rear intercepting mechanism in fig. 38 viewed along the traveling direction of the hollow shell.

Fig. 40 is a sectional view of the back intercept upper member shown in fig. 39, parallel to the traveling direction of the hollow shell.

Fig. 41 is a sectional view of the under back intercept member shown in fig. 39, parallel to the direction of travel of the hollow shell.

Fig. 42 is a sectional view of the rear intercepting left member shown in fig. 39, parallel to the traveling direction of the hollow shell.

Fig. 43 is a sectional view of the back catching right member shown in fig. 39 parallel to the traveling direction of the hollow shell.

Fig. 44 is a front view of the rear catching mechanism in a different form from fig. 39.

Fig. 45 is a front view of the rear intercepting mechanism of a different form from fig. 39 and 44.

Fig. 46 is a front view of the rear catching mechanism in a different form from fig. 39, 44 and 45.

Fig. 47 is a front view of the rear catching mechanism in a different form from fig. 39 and 44 to 46.

Fig. 48 is a front view of the rear catching mechanism in a different form from fig. 39 and 44 to 47.

Fig. 49 is a front view of the rear interception mechanism showing a state where a plurality of interception members in fig. 48 are brought close to the outer surface of the hollow shell in piercing-rolling or elongating-rolling.

Fig. 50 is an enlarged view of the vicinity of the exit side of the inclined roll in the piercing mill according to embodiment 7.

Fig. 51 is a graph showing the relationship between the density of the amount of water cooled on the outer surface and the density of the amount of water cooled on the inner surface in example 1.

Fig. 52 is a graph showing the relationship between the experiment elapsed time and the heat transfer coefficient in example 2.

Fig. 53 is a longitudinal sectional view along the axial direction and a transverse sectional view perpendicular to the axial direction of the steel pipe used in example 3.

Fig. 54 is a side view and a cross-sectional view perpendicular to the axial direction of a dummy mandrel used in example 3.

Fig. 55 is a side view and a cross-sectional view perpendicular to the axial direction of a dummy mandrel used in the example other than that of fig. 54.

FIG. 56 is a schematic diagram for explaining the test method in examples.

Fig. 57 is a graph showing the relationship between elapsed time (seconds) and temperature (deg.c) when the inner surface of the steel pipe was water-cooled using the dummy plug of fig. 54.

Fig. 58 is a graph showing the relationship between elapsed time (seconds) and temperature (deg.c) when the inner surface of the steel pipe was water-cooled using the dummy plug of fig. 55.

Detailed Description

The present inventors investigated and studied the reasons for the following: when the techniques of patent documents 1 and 2 are applied, the temperature difference between the front end portion and the rear end portion in the axial direction (longitudinal direction) of the hollow shell after the piercing-rolling or the elongating is not sufficiently reduced. Here, the tip end portion of the hollow shell means an end portion which has first passed through the plug during piercing-rolling or elongating, of both end portions in the axial direction of the hollow shell. The rear end portion of the hollow shell means an end portion which has passed through the plug at the end of piercing-rolling or elongating. In the present specification, the direction of each configuration of the piercing machine is defined as "front" on the entry side of the piercing machine and "rear" on the exit side of the piercing machine.

As a result of investigations and studies conducted by the present inventors, it has been found that: when the techniques of patent documents 1 and 2 are applied, the following problems may occur. In patent documents 1 and 2, in piercing rolling or elongating rolling, cooling water or a cooling fluid is continuously sprayed from the rear end portion of the plug or the front end portion of the plug toward the inner surface of the hollow shell. In this case, the inner surface portion of the hollow shell immediately after passing through the plug is cooled. However, the coolant sprayed from the plug or the plug toward the inner surface of the hollow shell hits the inner surface of the hollow shell and drops downward. The dropped coolant tends to accumulate in the inner surface portion located below the mandrel bar among the inner surfaces of the hollow shell in the piercing-rolling and elongating.

In the initial stage of the piercing-rolling or the elongating-rolling, the leading end portion of the rolled hollow shell passes through the plug 2. At this time, the leading end portion of the hollow shell becomes an open space, while the portion of the hollow shell where the plug 2 is located becomes a closed space. As the rolling proceeds, the distance from the rear end portion of the plug 2, which becomes a closed space, to the front end (open space) of the hollow shell becomes longer. The longer the distance to the open space is, the longer (wider) the coolant accumulates in the longitudinal direction of the hollow shell. The inner surface portion where the coolant is accumulated is cooled, but the range in which the coolant is accumulated changes with the rolling. Therefore, the cooling time at each position in the longitudinal direction of the hollow shell is generated to be short.

Specifically, the leading end portion of the hollow shell is easily cooled by the stored coolant for a long time, and the temperature is lowered. On the other hand, the inner surface of the hollow shell is naturally absent at a position rearward of the rear end portion of the hollow shell. Therefore, if the rear end portion of the hollow shell passes through the plug, the coolant does not accumulate and flows to the outside of the hollow shell. As a result, the cooling time of the inner surface of the rear end portion of the hollow shell is shorter than the cooling time of the inner surface of the front end portion of the hollow shell. As a result, a temperature difference occurs between the front end portion and the rear end portion of the hollow shell.

Based on the above new findings, the present inventors have studied a method of suppressing the temperature difference between the front end portion and the rear end portion of the hollow shell.

First, when piercing-rolling or elongating is performed using a plug, the reduction (piercing-rolling or elongating) is completed immediately after the material (round billet or hollow shell) passes through the plug. Therefore, no new heat is generated in the hollow shell passing through the plug. Therefore, it is preferable to cool the inner surface portion of the hollow shell which has passed through the plug and has a high temperature due to heat generation by the working.

Here, a region having a specific length in the axial direction (longitudinal direction) of the plug at the front end portion of the plug adjacent to the rear end of the plug is defined as a cooling region. An inner surface cooling mechanism is provided in the cooling zone, and the cooling liquid is sprayed from the cooling zone to cool the inner surface portion of the hollow shell through which the cooling liquid passes. Further, an inner surface intercepting means is provided at a portion of the mandrel bar adjacent to and rearward of the cooling zone. The inner surface intercepting means inhibits the coolant sprayed in the cooling zone by the cooling means from contacting an inner surface portion of the hollow shell located rearward of the cooling zone. With the above-described mechanism, the region of the hollow shell cooled by the coolant is limited to the cooling region during piercing-rolling or elongating. Therefore, the time for cooling by the coolant is constant at each position in the longitudinal direction of the inner surface of the hollow shell. As a result, the temperature difference between the front end portion and the rear end portion of the hollow shell is suppressed in the piercing-rolling or the elongating.

As described above, the present invention is achieved based on a technical idea which is completely different from the conventional technical idea, and its features are as follows.

The piercing mill having the structure according to (1) is a piercing mill for producing a hollow shell by piercing-rolling or elongating a raw material,

the piercing machine includes:

a plurality of inclined rolls disposed around a pass line through which a material passes;

a plug disposed on a pass line between the plurality of inclined rolls; and

a plug extending rearward of the plug along a rolling line from a rear end of the plug,

the core rod includes:

a rod body;

a coolant flow path formed in the rod main body, the coolant flowing through the coolant flow path;

an inner surface cooling mechanism which is disposed in a cooling zone of the rod main body, the cooling zone having a specific length in the axial direction of the mandrel bar and being located at the tip end portion of the mandrel bar, and which, during piercing rolling or elongation rolling, sprays a cooling liquid supplied from the cooling liquid flow path to the outside of the rod main body to cool the inner surface of the hollow shell during travel in the cooling zone; and

and an inner surface intercepting means which is disposed at the rear of the cooling zone so as to be adjacent to the cooling zone, and which suppresses the coolant injected to the outside of the rod main body from coming into contact with the inner surface of the hollow shell after the coolant has exited from the cooling zone during piercing rolling or elongating rolling.

In the piercing mill having the structure according to (1), the inner surface cooling means cools the inner surface of the hollow shell during the travel of the cooling zone of a specific length in the hollow shell that has passed through the plug after piercing-rolling or after elongating-rolling. The inner surface intercepting means disposed rearward of the cooling zone so as to be adjacent to the cooling zone suppresses the coolant that cools the inner surface of the hollow shell in the cooling zone from contacting the inner surface of the hollow shell after the coolant exits from the cooling zone. Therefore, the inner surface of the hollow shell is cooled by the coolant in the cooling zone, but is less likely to be cooled by the coolant in a position rearward of the cooling zone. Therefore, when piercing-rolling or elongating is performed using the piercing mill having the structure according to (1), the hollow shell is stably cooled in a certain region (cooling region). As a result, the variation of the cooling time in the axial direction of the hollow shell can be suppressed, and the temperature variation in the axial direction of the hollow shell, in particular, the temperature difference between the front end portion and the rear end portion of the hollow shell can be reduced.

The piercing machine according to the structure of (2) is the piercing machine of (1), wherein,

the inner surface intercepting means intercepts the coolant sprayed to the outside of the rod main body, and causes the coolant to be accumulated between the rod main body and the inner surface of the hollow shell in the cooling region.

In the piercing machine of the structure according to (2), the inner surface intercepting means intercepts the coolant so that the coolant is accumulated in the gap between the rod main body and the inner surface of the hollow shell in the cooling zone. Therefore, the hollow shell can be further cooled in the cooling region.

The piercing machine according to the structure of (3) is the piercing machine of (1) or (2), wherein,

the mandrel further includes a compressed gas flow path formed in the mandrel body for the passage of compressed gas,

the inner surface intercepting means injects the compressed gas supplied from the compressed gas flow path to the outside of the rod main body during piercing rolling or elongating rolling, thereby suppressing the coolant injected to the outside of the rod main body from contacting the inner surface of the hollow shell after coming out of the cooling zone.

In the piercing machine according to the structure of (3), the inner surface intercepting means injects the compressed gas toward the outside of the rod main body behind the cooling zone. Thus, when the coolant injected into the cooling zone attempts to flow rearward of the cooling zone, the compressed gas blows off the coolant and prevents the coolant from contacting the inner surface of the hollow shell after the coolant exits from the cooling zone. Thereby, the hollow shell after piercing-rolling or elongating and passing through the plug is stably cooled in a certain region (cooling region). As a result, the variation of the cooling time in the axial direction of the hollow shell can be suppressed, and the temperature variation in the axial direction of the hollow shell, in particular, the temperature difference between the front end portion and the rear end portion of the hollow shell can be reduced.

The piercing machine according to the structure of (4) is the piercing machine of (3), wherein,

the inner surface intercepting means intercepts the coolant injected to the outside of the rod main body with the compressed gas injected to the outside of the rod main body, and accumulates the coolant between the rod main body and the inner surface of the hollow shell in the cooling zone.

In the piercing machine according to the configuration of (4), the compressed gas injected from the inner surface intercepting means becomes a weir to intercept the coolant. Therefore, in the cooling region, the coolant is accumulated in the gap between the rod main body and the inner surface of the hollow shell. As a result, the hollow shell can be further cooled.

The piercing machine according to the structure of (5) is the piercing machine of (1) or (2), wherein,

the inner surface intercepting means includes an inner surface intercepting member disposed behind the cooling zone so as to be adjacent to the cooling zone, extending in a circumferential direction of the rod main body,

the height of the inner surface intercepting member is lower than the difference between the maximum radius of the plug and the radius of the rod body at the position where the inner surface intercepting member is disposed.

In the piercing machine according to the configuration of (5), the inner surface intercepting member is disposed at the rear end of the cooling zone so as to be adjacent to the cooling zone. The inner surface intercepting member functions as a weir that suppresses the coolant sprayed to the outside of the rod main body from coming into contact with the inner surface of the hollow shell after exiting from the cooling zone.

Further, the height of the inner surface intercepting member is lower than the difference between the maximum radius of the plug and the radius of the rod main body at the position where the inner surface intercepting member is disposed. Therefore, the inner surface intercepting member does not come into contact with the inner surface of the hollow shell passed through the plug during piercing-rolling or elongating-rolling, and the inner surface of the hollow shell is not pressed down.

The piercing machine according to the structure of (6) is the piercing machine of (5), wherein,

the inner surface intercepting means intercepts the coolant sprayed to the outside of the rod main body by the inner surface intercepting member, and causes the coolant to be accumulated between the rod main body and the inner surface of the hollow shell in the cooling region.

In the piercing machine according to the configuration of (6), the inner surface intercepting member becomes a weir to intercept the coolant. Therefore, in the cooling region, the coolant is accumulated in the gap between the rod main body and the inner surface of the hollow shell. As a result, the hollow shell can be further cooled.

The piercing machine having the structure according to (7) is the piercing machine according to any one of (1) to (6), wherein the plug further includes:

a liquid discharge flow path formed in the rod main body and through which the coolant ejected to the outside of the rod main body flows; and

and 1 or more drain holes which are disposed in the cooling region of the rod main body, are connected to the drain flow path, and collect the coolant sprayed to the outside of the rod main body.

In the piercing machine having the structure according to (7), the coolant used for cooling the hollow shell in the cooling zone is collected by the drain holes disposed in the cooling zone. Therefore, new coolant can be sequentially supplied into the cooling region, and the cooling efficiency can be improved.

The piercing machine having the structure according to (8) is the piercing machine according to any one of (1) to (7),

the inner surface cooling mechanism includes a plurality of coolant ejection holes arranged in the circumferential direction of the rod body or arranged in the circumferential direction and the axial direction of the rod body in the cooling region for ejecting the coolant.

In the piercing machine according to the structure of (8), the plurality of coolant ejection holes are arranged in at least the circumferential direction. Therefore, the inner surface of the hollow shell is easily cooled uniformly in the circumferential direction.

The piercing machine according to the structure of (9) is the piercing machine of (8), wherein,

the plurality of coolant ejection holes are directed toward the circumferential direction of the rod body as viewed in the traveling direction of the hollow shell,

the inner surface cooling mechanism sprays the coolant from the plurality of coolant spray holes along the circumferential direction of the rod body, thereby causing the coolant in the cooling region to revolve around the rod body.

The piercing machine according to the structure of (9) jets the cooling liquid along the circumferential direction of the rod body from the plurality of cooling liquid jet holes. Thereby, in the cooling zone, the coolant forms a swirling flow that swirls around the rod main body. The rotational flow can suppress variation in the flow of the coolant in the circumferential direction of the rod main body. As a result, uneven cooling in the circumferential direction can be suppressed on the inner surface of the hollow shell.

The piercing machine according to the structure of (10) is the piercing machine of (9), wherein,

the plurality of coolant spray holes are oriented circumferentially of and rearwardly of the rod body,

the inner surface cooling mechanism sprays the cooling liquid from the plurality of cooling liquid spray holes toward the circumferential direction of the rod main body and the rear side of the rod main body, thereby making the cooling liquid in the cooling area revolve around the rod main body.

In the piercing machine having the structure according to (10), the coolant forms a swirling flow that flows along the circumferential direction of the rod main body and flows rearward. Therefore, the variation in the flow of the coolant can be further suppressed, and the cooling unevenness in the circumferential direction can be suppressed on the inner surface of the hollow shell.

The piercing machine according to the structure of (11) is the piercing machine of (3) or (4), wherein,

the inner surface cooling mechanism includes a plurality of coolant ejection holes arranged in a circumferential direction of the rod body or in a circumferential direction and an axial direction of the rod body in the cooling region for ejecting the coolant,

the inner surface intercepting means includes a plurality of compressed gas injection holes arranged in a circumferential direction of the rod main body or in a circumferential direction and an axial direction of the rod main body for injecting compressed gas, in a contact suppression region disposed rearward of the cooling region so as to be adjacent to the cooling region.

In the piercing machine according to the structure of (11), the plurality of coolant ejection holes are arranged in at least the circumferential direction in the cooling zone, and the plurality of compressed gas ejection holes are arranged in at least the circumferential direction in the contact suppression zone. Therefore, the cooling unevenness in the circumferential direction of the inner surface of the hollow shell can be further suppressed.

The piercing machine according to the structure of (12) is the piercing machine of (11), wherein,

the plurality of compressed gas injection holes are directed in the circumferential direction of the rod main body as viewed in the traveling direction of the hollow shell,

the inner surface intercepting means injects the compressed gas from the compressed gas injection hole along the circumferential direction of the rod main body, thereby revolving the compressed gas in the contact suppression area around the rod main body.

In the piercing machine having the structure according to (12), the cooling liquid forms a swirling flow in the cooling zone, and the compressed gas injected by the inner surface intercepting means also forms a swirling flow in the contact suppressing zone disposed adjacent to the cooling zone and behind the cooling zone. The swirling flow of the compressed gas rapidly blows off the coolant entering toward the contact suppression area. Therefore, the cooling unevenness in the circumferential direction of the inner surface of the hollow shell in the cooling region can be suppressed, and the coolant can be suppressed from contacting the inner surface of the hollow shell after coming out of the cooling region.

The piercing machine according to the structure of (13) is the piercing machine of (12), wherein,

the plurality of compressed gas injection holes are directed toward the circumferential direction of the rod main body and rearward of the rod main body,

the inner surface intercepting means injects the compressed gas from the compressed gas injection hole toward the circumferential direction of the rod main body and the rear side of the rod main body, thereby rotating the compressed gas in the contact suppression area around the rod main body.

In the piercing machine having the structure according to (13), the compressed gas forms a swirling flow which flows along the circumferential direction of the rod main body and flows rearward. Therefore, the swirling flow of the compressed gas quickly blows the coolant entering the contact suppression area rearward of the rod main body. Therefore, the cooling liquid can be further prevented from coming into contact with the inner surface of the hollow shell after coming out of the cooling region while suppressing cooling unevenness in the circumferential direction of the inner surface of the hollow shell in the cooling region.

The piercing machine according to the structure of (14) is the piercing machine of (13), wherein,

the direction of rotation of the coolant ejected from the plurality of coolant ejection holes is right-handed or left-handed as viewed in the direction of travel of the hollow shell,

the direction of rotation of the compressed gas injected from the plurality of compressed gas injection holes is right-handed or left-handed as viewed in the traveling direction of the hollow shell,

the inner surface intercepting means ejects the compressed gas in such a manner that the rotation direction of the compressed gas is the same as the rotation direction of the cooling liquid.

In the piercing machine having the structure according to (14), the direction of rotation of the swirling flow of the compressed gas is the same as the direction of rotation of the swirling flow of the cooling liquid. In this case, the generation of turbulence caused by collision of the fluid (coolant, compressed gas) can be suppressed at the boundary between the cooling region and the contact suppression region. Therefore, the coolant can be prevented from staying at the boundary between the cooling region and the contact-preventing region, and the coolant entering the contact-preventing region can be blown off quickly by the swirling flow of the compressed gas.

The piercing machine having the structure according to (15) is the piercing machine according to any one of (12) to (14),

the inner surface cooling means includes a plurality of annularly arranged cooling liquid injection hole groups arranged in the axial direction of the rod main body in the cooling region of the rod main body,

the annularly arranged group of cooling liquid injection holes includes a plurality of cooling liquid injection holes arrayed in the circumferential direction at the same position in the axial direction of the rod body,

as for the inner surface cooling mechanism,

when the axial distance of the rod body, in which the swirl flow of the coolant advances to one revolution around the rod body, is defined as 1-revolution period distance, the distance between the adjacent annularly arranged coolant injection hole groups in the axial direction of the rod body is the same as 1-revolution period distance.

Here, "the same distance as 1 revolution period" means that the distance between the adjacent annularly arranged coolant injection hole groups is within ± 50% of the 1 revolution period distance. Preferably, the distance between the adjacent annularly arranged groups of the coolant injection holes is 1 revolution period distance ± 20%, more preferably 1 revolution period distance ± 10%.

In the piercing machine having the configuration according to (15), when the swirling flow of the coolant has traveled a distance of 1 revolution period, new coolant is supplied from the next rear annularly arranged coolant injection hole group. Therefore, compared with the case where a new coolant is supplied from the next annularly arranged coolant injection hole group before the swirling flow of the coolant reaches 1 revolution period distance, it is difficult to generate turbulence in the swirling flow of the coolant. Therefore, the circumferential cooling unevenness of the inner surface of the hollow shell can be further suppressed.

The piercing machine having the structure according to (16) is the piercing machine according to any one of (1) to (15), wherein further,

the piercing machine further includes an outer surface cooling mechanism disposed around the mandrel bar behind the plug,

the outer surface cooling mechanism sprays cooling fluid toward an upper portion of the outer surface, a lower portion of the outer surface, a left portion of the outer surface, and a right portion of the outer surface of the hollow shell during travel in the cooling zone, as viewed in a traveling direction of the hollow shell, to cool the hollow shell in the cooling zone.

In the piercing machine having the configuration according to (16), the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell that has been subjected to piercing-rolling or elongating-rolling are cooled in the cooling zone of a specific length behind the plug. In this case, the cooling fluid for cooling is sprayed to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell in the cooling zone to cool the hollow shell, and then flows downward below the hollow shell without staying in the hollow shell. Therefore, the hollow shell is cooled by the cooling fluid in the cooling region, and is less susceptible to cooling by the cooling fluid in regions other than the cooling region. Therefore, the time for cooling by the cooling fluid at each portion in the axial direction of the hollow shell becomes uniform to some extent. Therefore, it is possible to suppress the increase in the temperature difference between the front end portion and the rear end portion of the hollow shell due to the coolant accumulating on the inner surface of the hollow shell as in the conventional art, and it is possible to reduce the temperature variation in the axial direction of the hollow shell.

The piercing machine according to the structure of (17) is the piercing machine of (16), wherein,

the outer surface cooling mechanism includes:

an outer surface cooling upper member which is disposed above the mandrel bar as viewed in the traveling direction of the hollow shell, and which includes a plurality of cooling fluid upper injection holes for injecting a cooling fluid toward an upper portion of the outer surface of the hollow shell in the cooling zone;

an outer surface cooling lower member which is disposed below the mandrel bar as viewed in a traveling direction of the hollow shell, and which includes a plurality of cooling fluid lower ejection holes for ejecting a cooling fluid toward a lower portion of an outer surface of the hollow shell in the cooling zone;

an outer surface cooling left member which is disposed on the left side of the plug as viewed in the traveling direction of the hollow shell and includes a plurality of cooling fluid left spray holes for spraying a cooling fluid to the left portion of the outer surface of the hollow shell in the cooling zone; and

the outer surface cooling right member is disposed rightward of the plug as viewed in the traveling direction of the hollow shell, and includes a plurality of cooling fluid right spray holes for spraying a cooling fluid to the right portion of the outer surface of the hollow shell in the cooling zone.

In the piercing machine having the structure according to (17), the outer surface cooling mechanism sprays the cooling fluid from the outer surface cooling upper member disposed around the plug toward the upper portion of the outer surface of the hollow shell, sprays the cooling fluid from the outer surface cooling lower member toward the lower portion of the outer surface of the hollow shell, sprays the cooling fluid from the outer surface cooling left member toward the left side of the outer surface of the hollow shell, and sprays the cooling fluid from the outer surface cooling right member toward the right side of the hollow shell. In this way, the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell in the cooling region can be cooled. In the cooling region, the cooling fluid injected to the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell tends to fall directly downward due to gravity, and is difficult to flow out of the cooling region. Therefore, the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell in the other regions than the cooling region can be suppressed from being cooled by the cooling fluid injected in the cooling region. As a result, temperature variation in the axial direction of the hollow shell can be reduced.

The outer surface cooling upper member, the outer surface cooling lower member, the outer surface cooling left member, and the outer surface cooling right member may be independent members, or may be integrally connected to each other. For example, the left end of the outer surface-cooling upper member may be connected to the upper end of the outer surface-cooling left member, or the right end of the outer surface-cooling upper member may be connected to the upper end of the outer surface-cooling right member, as viewed in the traveling direction of the hollow shell. Further, the left end of the outer surface cooling lower member may be connected to the lower end of the outer surface cooling left member, or the right end of the outer surface cooling lower member may be connected to the lower end of the outer surface cooling right member, as viewed in the traveling direction of the hollow shell. In addition, the outer surface cooling upper member may include a plurality of independent members, the outer surface cooling lower member may include a plurality of independent members, the outer surface cooling left member may include a plurality of independent members, and the outer surface cooling right member may include a plurality of independent members.

The piercing machine according to the structure of (18) is the piercing machine of (16) or (17), wherein,

the piercing machine further includes a front intercepting means disposed behind the plug and around the mandrel in front of the outer surface cooling means,

the front interception mechanism comprises the following mechanisms: when the outer surface cooling means sprays the cooling fluid toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell to cool the hollow shell in the cooling region, the means blocks the cooling fluid from flowing to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell before entering the cooling region.

In the piercing machine having the structure according to (18), the front intercepting means intercepts the cooling fluid injected toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell in the cooling zone, and the cooling fluid flows toward the outer surface portion of the hollow shell in front of the cooling zone after coming into contact with the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell. Therefore, the cooling fluid injected from the outer surface cooling means to the outer surface of the hollow shell in the cooling zone is less likely to flow out forward in the cooling zone, and falls downward in the cooling zone due to gravity. Therefore, the temperature difference can be further suppressed at the front end portion and the rear end portion of the hollow shell. As a result, temperature variation in the axial direction of the hollow shell can be further reduced.

The piercing machine according to the structure of (19) is the piercing machine of (18), wherein,

the front interception mechanism comprises:

a front intercepting upper member which is arranged above the mandrel bar as viewed in a traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid upper injection holes that inject a front intercepting fluid toward an upper portion of an outer surface of the hollow shell located in the vicinity of an entrance side of the cooling zone and intercept a flow of the cooling fluid toward an upper portion of the outer surface of the hollow shell before entering the cooling zone;

a front intercepting left member which is disposed on the left side of the mandrel bar as viewed in the traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid lower injection holes that inject a front intercepting fluid toward the left portion of the outer surface of the hollow shell located in the vicinity of the entry side of the cooling zone and intercept a flow of the cooling fluid toward the left portion of the outer surface of the hollow shell before entering the cooling zone; and

and a front intercepting right member which is arranged on the right side of the mandrel bar as viewed in the traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid right injection holes that inject the front intercepting fluid toward the right portion of the outer surface of the hollow shell located in the vicinity of the entrance side of the cooling zone and intercept the flow of the cooling fluid toward the right portion of the outer surface of the hollow shell before entering the cooling zone.

In the piercing machine having the configuration according to (19), the forward intercepting upper member intercepts the cooling fluid, which comes into contact with the upper portion of the outer surface of the hollow shell in the cooling zone and splashes back, by the forward intercepting fluid injected to the vicinity of the inlet side of the cooling zone and attempts to fly forward of the cooling zone. The front intercepting left member intercepts, by a front intercepting fluid injected to the vicinity of the inlet side of the cooling zone, the cooling fluid which comes into contact with the left portion of the outer surface of the hollow shell in the cooling zone, splashes back, and attempts to fly out to the front of the cooling zone. The front intercepting right member intercepts, by a front intercepting fluid injected to the vicinity of the inlet side of the cooling zone, the cooling fluid which comes into contact with the right portion of the outer surface of the hollow shell in the cooling zone, splashes back, and attempts to fly out to the front of the cooling zone. Thus, the front intercepting fluid ejected from the front intercepting upper member, the front intercepting fluid ejected from the front intercepting left member, and the front intercepting fluid ejected from the front intercepting right member function as a weir (a protection wall). Therefore, the cooling fluid can be prevented from contacting the outer surface portion of the hollow shell in front of the cooling region, and temperature variation in the axial direction of the hollow shell can be reduced. Further, the cooling fluid injected from the outer surface cooling means toward the lower portion of the outer surface of the hollow shell in the cooling zone is likely to directly fall downward of the hollow shell due to gravity after coming into contact with the lower portion of the outer surface of the hollow shell. Therefore, the piercing machine having the structure according to (19) may not include the front catch lower member.

The vicinity of the entrance side of the cooling zone refers to the vicinity of the front end of the cooling zone. The range near the entrance side of the cooling zone is not particularly limited, and is, for example, a range within 1000mm before and after the entrance side (front end) of the cooling zone, and preferably a range within 500mm before and after the entrance side (front end) of the cooling zone.

The piercing machine according to the structure of (20) is the piercing machine of (19), wherein,

the front intercepting upper member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid upper jet holes toward an upper portion of the outer surface of the hollow shell located in the vicinity of the entry side of the cooling zone,

the front intercepting left member jets the front intercepting fluid diagonally rearward from the plurality of front intercepting fluid left jet holes toward a left portion of the outer surface of the hollow shell located in the vicinity of the entry side of the cooling zone,

the front intercepting right member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid right jet holes toward a right portion of the outer surface of the hollow shell located in the vicinity of the entry side of the cooling zone.

In the piercing machine having the configuration according to (20), the front intercepting upper member jets the front intercepting fluid obliquely rearward from the front intercepting fluid upper jet holes toward an upper portion of the outer surface of the hollow shell in the vicinity of the entry side of the cooling zone. Therefore, the front interception upper member forms a weir (a protection wall) that intercepts the fluid from above and extends obliquely rearward toward the upper portion of the outer surface of the hollow shell. Similarly, the front intercepting left member jets the front intercepting fluid obliquely rearward from the front intercepting fluid left jet hole toward a left portion of the outer surface of the hollow shell in the vicinity of the entry side of the cooling zone. Therefore, the front-intercepting left member forms a front-intercepting weir (a protective wall) that extends obliquely rearward from the left toward the left portion of the outer surface of the hollow shell. Similarly, the front intercepting right member jets the front intercepting fluid obliquely rearward from the front intercepting fluid right jet hole toward a right portion of the outer surface of the hollow shell in the vicinity of the entry side of the cooling zone. Therefore, the front-intercepting right member forms a weir (a protective wall) that intercepts the fluid from the right and extends obliquely rearward toward the right portion of the outer surface of the hollow shell. These dams intercept cooling fluid which splashes back in contact with the outer surface portion of the hollow shell in the cooling zone and which is intended to fly forward of the cooling zone. Further, the front dam fluid constituting the dam easily flows into the cooling zone after coming into contact with the outer surface portion of the hollow shell in the vicinity of the inlet side of the cooling zone. Therefore, the outer surface portion of the hollow shell in front of the front intercepted fluid cooling zone constituting the weir can be suppressed.

The piercing machine according to the structure of (21) is the piercing machine of (19) or (20), wherein,

the front intercepting means further includes a front intercepting member which is disposed below the mandrel bar as viewed in a traveling direction of the hollow shell, and which includes a plurality of front intercepting fluid lower ejecting holes that eject the front intercepting fluid toward a lower portion of the outer surface of the hollow shell located near an entrance side of the cooling zone and intercept a flow of the cooling fluid toward a lower portion of the outer surface of the hollow shell before entering the cooling zone.

In the piercing machine having the configuration according to (21), the front intercepting lower member, together with the front intercepting upper member, the front intercepting left member, and the front intercepting right member, sprays the front intercepting fluid to the vicinity of the inlet side of the cooling zone, and intercepts the cooling fluid which comes into contact with the lower portion of the outer surface of the hollow shell in the cooling zone, splashes back, and tries to fly out to the front of the cooling zone. Therefore, the cooling fluid can be further suppressed from contacting the outer surface portion of the hollow shell in front of the cooling region, and the temperature variation in the axial direction of the hollow shell can be further reduced.

The front intercepting upper member, the front intercepting lower member, the front intercepting left member, and the front intercepting right member may be independent members, or may be integrally connected to each other. For example, the left end of the front intercepting upper member may be connected to the upper end of the front intercepting left member or the right end of the front intercepting upper member may be connected to the upper end of the front intercepting right member as viewed in the traveling direction of the hollow shell. In addition, the left end of the front intercepting member may be connected to the lower end of the left front intercepting member or the right end of the front intercepting member may be connected to the lower end of the right front intercepting member as viewed in the traveling direction of the hollow shell. In addition, the front intercepting upper member may include a plurality of members independent of each other, the front intercepting lower member may include a plurality of members independent of each other, the front intercepting left member may include a plurality of members independent of each other, and the front intercepting right member may include a plurality of members independent of each other.

The piercing machine according to the structure of (22) is the piercing machine according to the structure of (21), wherein,

the front intercepting lower member jets the front intercepting fluid obliquely rearward from the plurality of front intercepting fluid lower jet holes toward a lower portion of the outer surface of the hollow shell located in the vicinity of the entry side of the cooling zone.

In the piercing machine having the structure according to (22), the front intercepting lower member injects the front intercepting fluid obliquely rearward from the front intercepting fluid lower injection holes toward the lower portion of the outer surface of the hollow shell near the entrance side of the cooling zone together with the front intercepting upper member, the front intercepting left member, and the front intercepting right member. Therefore, the front intercepting lower member forms a weir (a protective wall) for intercepting the fluid from the front, which extends obliquely rearward from below toward the lower portion of the outer surface of the hollow shell. These dams intercept cooling fluid which splashes back in contact with the outer surface portion of the hollow shell in the cooling zone and which is intended to fly forward of the cooling zone. Further, the front dam fluid constituting the dam easily flows into the cooling zone after coming into contact with the outer surface portion of the hollow shell in the vicinity of the inlet side of the cooling zone. Therefore, the outer surface portion of the hollow shell in front of the front intercepted fluid cooling zone constituting the weir can be suppressed.

The piercing machine having the structure according to (23) is the piercing machine according to any one of (16) to (22),

the piercing machine further includes a rear catching mechanism disposed around the mandrel bar behind the outer surface cooling mechanism,

the rear interception mechanism comprises the following mechanisms: when the outer surface cooling means sprays the cooling fluid toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell to cool the hollow shell, the means blocks the cooling fluid from flowing to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell after exiting from the cooling zone.

In the piercing machine having the structure according to (23), the backward intercepting means intercepts the cooling fluid injected toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell in the cooling zone, and after the cooling fluid comes into contact with the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell, the cooling fluid flows toward the outer surface portion of the hollow shell after the hollow shell exits from the cooling zone. Therefore, the occurrence of a temperature difference between the front end portion and the rear end portion of the hollow shell can be further suppressed. As a result, temperature variation in the axial direction of the hollow shell can be further reduced.

The piercing machine according to the structure of (24) is the piercing machine of (23), wherein,

the rear interception mechanism comprises:

a rear intercepting upper member which is arranged above the mandrel bar as viewed in a traveling direction of the hollow shell, and which includes a plurality of rear intercepting fluid upper ejecting holes that eject a rear intercepting fluid toward an upper portion of an outer surface of the hollow shell located in the vicinity of an exit side of the cooling zone and intercept a flow of the cooling fluid toward an upper portion of the outer surface of the hollow shell after exiting from the cooling zone;

a rear intercepting left member which is disposed on the left side of the plug as viewed in the traveling direction of the hollow shell, and which includes a plurality of rear intercepting fluid left injection holes that inject a rear intercepting fluid toward the left portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone and intercept the flow of the cooling fluid toward the left portion of the outer surface of the hollow shell after exiting from the cooling zone; and

and a rear intercepting right member which is disposed on the right side of the plug as viewed in the traveling direction of the hollow shell, and which includes a plurality of rear intercepting fluid right injection holes that inject a rear intercepting fluid toward the right portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone to intercept the flow of the cooling fluid toward the right portion of the outer surface of the hollow shell after the exit from the cooling zone.

In the piercing machine having the structure according to (24), the backward catching upper member catches the cooling fluid, which comes into contact with the upper portion of the outer surface of the hollow shell in the cooling zone and splashes back, by the backward catching fluid injected to the vicinity of the outlet side of the cooling zone, and which attempts to fly out backward of the cooling zone. The rear cutoff left member is configured to intercept, with a rear cutoff fluid injected toward the vicinity of the outlet side of the cooling zone, the cooling fluid which comes into contact with the left portion of the outer surface of the hollow shell in the cooling zone, splashes back, and attempts to fly out rearward of the cooling zone. The right backward intercepting member intercepts, by the backward intercepting fluid injected to the vicinity of the exit side of the cooling zone, the cooling fluid which comes into contact with the right portion of the outer surface of the hollow shell in the cooling zone, splashes back, and attempts to fly out backward of the cooling zone. Thus, the rear intercepting fluid ejected from the rear intercepting upper member, the rear intercepting fluid ejected from the rear intercepting left member, and the rear intercepting fluid ejected from the rear intercepting right member function as a weir (a protection wall). Therefore, the cooling fluid can be suppressed from contacting the outer surface portion of the hollow shell behind the cooling region, and temperature variation in the axial direction of the hollow shell can be reduced. Further, the cooling fluid injected from the outer surface cooling means toward the lower portion of the outer surface of the hollow shell in the cooling zone is likely to directly fall downward of the hollow shell due to gravity after coming into contact with the lower portion of the outer surface of the hollow shell. Therefore, the piercing machine having the structure of (24) may not include the rear catch lower member.

The vicinity of the exit side of the cooling zone refers to the vicinity of the rear end of the cooling zone. The range near the exit side of the cooling zone is not particularly limited, and is, for example, a range within 1000mm before and after the exit side (rear end) of the cooling zone, and preferably a range within 500mm before and after the exit side (rear end) of the cooling zone.

The piercing machine according to the structure of (25) is the piercing machine of (24), wherein,

the backward intercepting upper member jets the backward intercepting fluid diagonally forward from the plurality of backward intercepting fluid upper jet holes toward an upper portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone,

the backward intercepting left member jets the backward intercepting fluid diagonally forward from the plurality of backward intercepting fluid left jet holes toward a left portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone,

the backward intercepting right member jets the backward intercepting fluid diagonally forward from the plurality of backward intercepting fluid right jet holes toward a right portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone.

In the piercing machine having the structure according to (25), the backward intercepting upper member jets the backward intercepting fluid obliquely forward from the backward intercepting fluid upper jet hole toward an upper portion of the outer surface of the hollow shell in the vicinity of the outlet side of the cooling zone. Therefore, the rearward interception upper member forms a weir (a protection wall) that intercepts the fluid from above and extends diagonally forward toward an upper portion of the outer surface of the hollow shell. Similarly, the backward intercepting left member jets the backward intercepting fluid diagonally forward from the backward intercepting fluid left jet hole toward a left portion of the outer surface of the hollow shell in the vicinity of the exit side of the cooling zone. Therefore, the rear intercepting left member forms a weir (a protection wall) that intercepts the fluid from the left side obliquely forward toward the left portion of the outer surface of the hollow shell. Similarly, the right backward intercepting member jets the backward intercepting fluid diagonally forward from the right backward intercepting fluid jet hole toward a right portion of the outer surface of the hollow shell in the vicinity of the exit side of the cooling zone. Therefore, the right backward intercepting member forms a weir (a protective wall) that intercepts the fluid from the right obliquely forward toward the right portion of the outer surface of the hollow shell. These weir for intercepting the flow behind intercept the cooling fluid which splashes back by contacting with the outer surface portion of the hollow shell in the cooling zone and which attempts to fly out toward the rear of the cooling zone. Further, the rear intercepting fluid constituting the weir is likely to flow into the cooling zone after coming into contact with the outer surface portion of the hollow shell in the vicinity of the inlet side of the cooling zone. Therefore, the outer surface portion of the hollow shell that constitutes the rear of the fluid cooling area intercepted behind the weir can be suppressed.

The piercing machine according to the structure of (26) is the piercing machine of (24) or (25), wherein,

the backward intercepting means further includes a backward intercepting member which is disposed below the mandrel bar as viewed in a traveling direction of the hollow shell, and which includes a plurality of backward intercepting fluid lower ejecting holes that eject the backward intercepting fluid toward a lower portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone and intercept a flow of the cooling fluid toward a lower portion of the outer surface of the hollow shell after the exit from the cooling zone.

In the piercing machine having the structure according to (26), the rear intercepting lower member sprays the rear intercepting fluid to the vicinity of the outlet side of the cooling zone together with the rear intercepting upper member, the rear intercepting left member, and the rear intercepting right member, and intercepts the cooling fluid which comes into contact with the lower portion of the outer surface of the hollow shell in the cooling zone, splashes back, and tries to fly out to the rear of the cooling zone. Therefore, the cooling fluid can be suppressed from contacting the outer surface portion of the hollow shell behind the cooling region, and the temperature variation in the axial direction of the hollow shell can be further reduced.

Further, the rear intercepting upper member, the rear intercepting lower member, the rear intercepting left member, and the rear intercepting right member may be independent members, respectively, or may be integrally connected to each other. For example, the left end of the rear intercepting upper member may be connected to the upper end of the rear intercepting left member or the right end of the rear intercepting upper member may be connected to the upper end of the rear intercepting right member as viewed in the traveling direction of the hollow shell. In addition, the left end of the rear interception lower member can be connected with the lower end of the rear interception left member or the right end of the rear interception lower member can be connected with the lower end of the rear interception right member when viewed along the advancing direction of the hollow shell. In addition, the rear intercepting upper member may include a plurality of independent members, the rear intercepting lower member may include a plurality of independent members, the rear intercepting left member may include a plurality of independent members, and the rear intercepting right member may include a plurality of independent members.

The piercing machine according to the configuration of (27) is the piercing machine according to the configuration of (26), wherein,

the backward intercepting lower member jets the backward intercepting fluid obliquely forward from the plurality of backward intercepting fluid lower jet holes toward a lower portion of the outer surface of the hollow shell located in the vicinity of the exit side of the cooling zone.

In the piercing machine according to the configuration of (27), the rear intercepting lower member sprays the rear intercepting fluid obliquely forward from the rear intercepting fluid lower injection holes toward the lower portion of the outer surface of the hollow shell near the exit side of the cooling zone together with the rear intercepting upper member, the rear intercepting left member, and the rear intercepting right member. Therefore, the rearward interception lower member forms a weir (a protection wall) that intercepts the fluid rearward extending diagonally forward from below toward the lower portion of the outer surface of the hollow shell. The weir for these fluids intercepts the cooling fluid which splashes back in contact with the outer surface portion of the hollow shell in the cooling zone and which is intended to fly out behind the cooling zone. Further, the rear intercepting fluid constituting the weir easily flows into the cooling zone after coming into contact with the outer surface portion of the hollow shell in the vicinity of the outlet side of the cooling zone. Therefore, the outer surface portion of the hollow shell that constitutes the rear of the fluid cooling area intercepted behind the weir can be suppressed.

The plug having the structure according to (28) is the plug according to any one of (1) to (27).

The method for producing a seamless metal pipe according to the feature of (29) is a method for producing a seamless metal pipe using the piercing machine according to any one of (1) to (27),

the method for manufacturing the seamless metal tube comprises the following steps:

a rolling step of producing a hollow shell by piercing-rolling or elongating a raw material using a piercing mill;

in the rolling step, the inner surface of the hollow shell in the cooling zone is cooled by spraying a cooling liquid to the outside of the rod main body by the inner surface cooling means, and the contact between the cooling liquid sprayed to the outside of the rod main body and the inner surface of the hollow shell after coming out of the cooling zone is suppressed by the inner surface intercepting means disposed to the rear of the cooling zone so as to be adjacent to the cooling zone.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding portions in the drawings are denoted by the same reference numerals, and description thereof will not be repeated.

[ embodiment 1]

Fig. 1 is a side view of the piercing machine according to embodiment 1. As described above, in the present specification, a piercing mill refers to a rolling mill including a plug and a plurality of inclined rolls. The piercing mill is a piercing mill for piercing and rolling a round billet, for example, or a drawing mill for drawing and rolling a hollow billet. In the present specification, in the case where the piercing machine is a piercing mill, the raw material is a round billet. In the case where the piercing mill is an elongation mill, the raw material is a hollow shell.

In this specification, the raw material travels on the pass line from the front toward the rear of the piercing machine. Therefore, in the piercing machine, the inlet side of the piercing machine corresponds to the "front", and the outlet side of the piercing machine corresponds to the "rear".

Referring to fig. 1, a piercing machine 10 includes a plurality of inclined rolls 1, plugs 2, and plug 3. In the present specification, as shown in fig. 1, the entry side of the piercing machine 10 is defined as "front (reference numeral F in the drawing)" and the exit side of the piercing machine 10 is defined as "rear (reference numeral B in the drawing)".

In fig. 1, the inclined rolls 1 are disposed at equal intervals around a barrel-shaped inclined roll or other types of inclined rolls 1, while in fig. 1, two inclined rolls 1 are disposed around a pass line P5639, the inclined rolls 1 may be disposed at 3 or more intervals around a pass line P L when viewed in the direction of travel of the material, and preferably, the inclined rolls 1 are disposed at equal intervals around the pass line P L when viewed in the direction of travel of the material, and the inclined rolls 1 are disposed at equal intervals around the pass line P L, at an angle of inclination of two inclined rolls 1 disposed around the pass line P L, at an angle of inclination of two inclined rolls P733, at an angle of inclination of 120, at an angle of inclination of 3, at an angle of inclination of P4933, at an angle of inclination of P3, at an angle of an intersection of an angle of a pass line P3, with respect to the pass line P4933, with respect to the pass line P3, and an angle of a pass line P4933 when viewed in the pass line P2, and an angle of the pass line P4933 when viewed in the pass line P3, and the pass line P4933, when viewed in the pass line P3, and the pass line P2, see fig. 1.

In the present specification, the plug 2 is disposed between the plurality of inclined rolls 1 and at the pass line P L, and the phrase "the plug 2 is disposed at the pass line P L" means that the plug 2 overlaps the pass line P L when viewed along the traveling direction of the material, that is, when the piercing mill 10 is viewed from the front F toward the rear B, and more preferably, the center axis of the plug 2 coincides with the pass line P L.

The plug 2 has, for example, a shell shape. That is, the outer diameter of the front portion of the plug 2 is smaller than the outer diameter of the rear portion of the plug 2. Here, the front portion of the plug 2 refers to a portion of the plug 2 located forward of the center position in the longitudinal direction (axial direction). The rear portion of the plug 2 is a portion of the plug 2 located rearward of the central position in the front-rear direction. The front portion of the plug 2 is disposed in front of (on the inlet side of) the piercing machine 10, and the rear portion of the plug 2 is disposed behind (on the outlet side of) the piercing machine 10.

Here, the phrase "the plug 3 is disposed on the pass line P L" means that the plug 3 overlaps the pass line P L when viewed along the traveling direction of the material (that is, when viewed from the entry side toward the exit side of the piercing mill 10), and more preferably, the center axis of the plug 3 coincides with the pass line P L.

The front end of the plug 3 is connected to the center of the rear end face of the plug 2. The connection method is not particularly limited. For example, threads are formed at the center of the rear end surface of the plug 2 and the tip of the plug 3, and the plug 3 is connected to the plug 2 by these threads. The plug 3 may be connected to the rear end surface center portion of the plug 2 by a method other than a screw. That is, the method of connecting the plug 3 and the plug 2 is not particularly limited.

The piercing machine 10 may further include a pusher 4, the pusher 4 may be disposed in front of the piercing machine 10 and on the pass line P L, and the pusher 4 may be configured to contact an end surface of the material 20 and push the material 20 toward the plug 2.

The structure of the pusher 4 is not particularly limited as long as the raw material 20 can be pushed toward the plug 2. The pusher 4 includes, for example, as shown in fig. 1, a cylinder main body 41, a cylinder shaft 42, a connecting member 43, and a rod 44. The rod 44 is coupled to the cylinder shaft 42 by a coupling member 43 so as to be rotatable in the circumferential direction. The connecting member 43 includes, for example, a bearing for enabling the rod 44 to rotate in the circumferential direction.

The cylinder body 41 is hydraulically or electrically operated, and moves the cylinder shaft 42 forward and backward. The pusher 4 brings the end surface of the rod 44 into contact with the end surface of the raw material (round billet or hollow shell) 20, and moves the cylinder shaft 42 and the rod 44 forward by the cylinder body 41. Thereby, the pusher 4 pushes the raw material 20 toward the plug 2.

The pusher 4 pushes the material 20 along the pass line P L and between the inclined rolls 1, when the material 20 comes into contact with the inclined rolls 1, the inclined rolls 1 push the material 20 toward the plug 2 while rotating the material 20 in the circumferential direction of the material 20, and when the piercing mill 10 is a piercing mill, the inclined rolls 1 push the round billet as the material 20 toward the plug 2 while rotating the round billet as the material 20 in the circumferential direction to produce a hollow shell by piercing-rolling, and when the piercing mill 10 is an extension mill, the inclined rolls 1 insert the plug 2 into the hollow shell as the material 20 and perform extension rolling (tube expansion rolling) to extend the hollow shell, and the piercing mill 10 may not include the pusher 4.

The piercing mill 10 may further include an inlet groove 5, the raw material (round billet or hollow shell) 20 before piercing-rolling is placed in the inlet groove 5, as shown in fig. 3, the piercing mill 10 may have a plurality of guide rolls 6 around a pass line P L, the plug 2 may be disposed between the plurality of guide rolls 6, the guide rolls 6 may be disposed between the plurality of inclined rolls 1 around a pass line P L, the guide rolls 6 may be, for example, disc rolls, and the piercing mill 10 may not include the inlet groove 5 or the guide rolls 6.

Fig. 4 is an enlarged view of the plug 2 and the mandrel 3 in fig. 1. Referring to fig. 4, the piercing machine 10 receives a coolant supply from the coolant supply device 7. The coolant supply device 7 supplies coolant for cooling the inner surface of the hollow shell 50 during piercing-rolling or elongating-rolling to the plug 3. The coolant supply device 7 includes a supply device 71 and a pipe 72. The feeder 71 includes, for example: a storage tank for storing a coolant; and a pump for supplying the coolant in the reservoir to the pipe 72. The pipe 72 connects the mandrel bar 3 and the feeder 71. The pipe 72 feeds the coolant fed from the feeder 71 to the mandrel bar 3. Here, the coolant is not particularly limited as long as it can cool the hollow shell 50. Preferably, the cooling fluid is water.

[ Structure of core rod 3 ]

Referring to fig. 4, the plug 3 extends from the center of the rear end face of the plug 2 along the pass line P L, the plug 3 includes a rod-shaped main body 31, the cross-sectional shape of the rod main body 31 perpendicular to the axial direction (the longitudinal direction, corresponding to arrows F and B in the drawing) is, for example, a circular shape, and the rod main body 31 includes a cooling zone 32 and a contact suppression zone 33 extending in the axial direction of the rod main body 31.

Specifically, the cooling zone 32 is a range from the front end of the rod main body 31 (i.e., the connection position with the rear end of the plug 2) to a position spaced a predetermined length rearward of the plug 3. the axial length L32 of the cooling zone 32 is not particularly limited, the axial length L32 of the cooling zone 32 is, for example, greater than 1/10 and less than 1/2 of the entire length of the plug 3. in another example, when the length of the hollow shell to be produced is 6m, the axial length L32 of the cooling zone 32 is, for example, 2 m.

The contact suppression region 33 is adjacent to the cooling region 32 and is disposed rearward (on the opposite side of the plug 2) of the cooling region 32, the length L33 of the contact suppression region 33 is not particularly limited, the length L33 of the contact suppression region 33 may be the same as the length L32 of the cooling region 32, may be longer than the length L32 of the cooling region 32, or may be shorter than the length L32 of the cooling region 32, and the portion of the rod main body 31 other than the cooling region 32 may be the contact suppression region 33.

Fig. 5 is a cross-sectional view (longitudinal sectional view) of the plug 2 and the mandrel 3 shown in fig. 4, including the central axis. Referring to fig. 5, the mandrel 3 further includes a coolant flow path 34 and an inner surface cooling mechanism 340. The coolant passage 34 is formed in the rod main body 31 and allows the coolant supplied from the coolant supply device 7 to pass therethrough. The coolant flow path 34 extends inside the rod main body 31 along the axial direction of the rod main body 31. The coolant flow path 34 is connected to the pipe 72, and receives the supply of the coolant from the pipe 72.

The inner surface cooling means 340 is disposed in the cooling region 32 corresponding to the tip portion of the rod main body 31. In this example, inner surface cooling mechanism 340 includes a plurality of coolant jets 341. The plurality of coolant ejection holes 341 are connected to the coolant flow path 34, and eject the coolant to the outside of the cooling zone 32 during piercing and rolling or during elongating. In fig. 4 and 5, a plurality of coolant ejection holes 341 are arranged in the circumferential direction and the axial direction of the rod body 31. However, the plurality of coolant ejection holes 341 may be arranged in the circumferential direction of the rod body 31, or in the circumferential direction and the axial direction. For example, the plurality of coolant ejection holes 341 may be arranged in the circumferential direction and not arranged in the axial direction. Preferably, a plurality of coolant ejection holes 341 are arranged in the circumferential direction and/or the axial direction of the rod body 31. As discussed subsequently, inner surface cooling mechanism 340 includes a plurality of nozzles, each having a coolant ejection hole 341.

The mandrel 3 further comprises an inner surface interception mechanism 350. The inner surface intercepting means 350 is disposed in the contact suppressing region 33. During piercing-rolling or elongation rolling, the inner surface intercepting means 350 ejects compressed gas from the contact suppressing region 33 to intercept or blow away the coolant flowing backward from the cooling region 32. Thereby, the coolant is suppressed from contacting the inner surface portion of the hollow shell in the contact suppression region 33 during piercing rolling or elongating rolling.

Specifically, as shown in fig. 4, the piercing machine 10 also receives a supply of compressed gas from the gas supply device 8. The gas supply device 8 supplies compressed gas for blowing away the coolant to the rod main body 31. The gas supply device 8 includes a tank 81 for storing, for example, high-pressure gas, and a pipe 82. The piping 82 connects the air tank 81 and the rod main body 31. The pipe 82 feeds the compressed gas sent from the gas tank 81 to the rod main body 31. Here, the compressed gas may be, for example, compressed air, or an inert gas such as argon or nitrogen. Preferably, the compressed gas is compressed air.

Referring to fig. 5, the plug 3 includes a gas flow path 35. The gas flow path 35 extends inside the rod main body 31 in the axial direction of the rod main body 31. The gas flow path 35 is connected to a pipe 82 (see fig. 4), and receives a supply of compressed gas from the pipe 82.

The inner surface intercepting means 350 includes a plurality of compressed gas injection holes 351. The plurality of compressed gas injection holes 351 are connected to the gas flow path 35, and inject compressed gas to the outside of the contact suppression region 33 during piercing rolling or elongation rolling. In fig. 4 and 5, a plurality of compressed gas injection holes 351 are arranged in the circumferential direction and the axial direction of the rod main body 31. However, the plurality of compressed gas injection holes 351 may be arranged in the circumferential direction of the rod main body 31, or in the circumferential direction and the axial direction. Specifically, the plurality of compressed gas injection holes 351 may be arranged in the circumferential direction, but not in the axial direction. Preferably, the plurality of compressed gas injection holes 351 are arranged in the circumferential direction and/or the axial direction of the rod main body 31. As will be discussed later, the inner surface intercepting mechanism 350 includes a plurality of nozzles, each having a compressed gas injection hole 351.

Fig. 6 is a cross-sectional view of the mandrel 3 perpendicular to the axial direction at the line a-a in the cooling zone 32 in fig. 5. Referring to fig. 6, the coolant flow field 34 is disposed in parallel with the gas flow field 35 at the center of the rod main body 31. A plurality of coolant ejection holes 341 are arranged in the circumferential direction of the rod body 31. The plurality of coolant ejection holes 341 may be arranged at equal intervals in the circumferential direction of the rod body 31, or may be arranged irregularly. Preferably, the coolant ejection holes 341 are arranged at equal intervals in the circumferential direction of the rod body 31. Each of the coolant ejection holes 341 is connected to the coolant flow path 34. As shown in fig. 5 and 6, in the present embodiment, a plurality of coolant ejection holes 341 are arranged in the cooling zone 32 in the circumferential direction and the axial direction of the rod body 31. However, the plurality of coolant ejection holes 341 may be arranged at least only in the circumferential direction of the rod body 31.

Fig. 7 is a cross-sectional view of the mandrel 3 perpendicular to the axial direction at a line B-B within the contact-restraining zone 33 in fig. 5. Referring to fig. 7, similarly to the cross-sectional view (fig. 6) in the cooling region 32, the gas flow path 35 is also arranged in parallel with the coolant flow path 34 in the center portion of the rod main body 31 in the cross-sectional view in the contact-suppressing region 33. The plurality of compressed gas injection holes 351 are arranged in the circumferential direction of the rod main body 31. The plurality of compressed gas injection holes 351 may be arranged at equal intervals in the circumferential direction of the rod main body 31, or may be arranged irregularly. Preferably, the compressed gas injection holes 351 are arranged at equal intervals in the circumferential direction of the rod main body 31. Each compressed gas injection hole 351 is connected to the gas flow path 35. As shown in fig. 5 and 7, in the present embodiment, the plurality of compressed gas injection holes 351 are arranged in the circumferential direction and the axial direction of the rod main body 31 in the contact suppressing region 33. However, the plurality of compressed gas injection holes 351 may be arranged at least only in the circumferential direction of the rod main body 31.

[ liquid discharge mechanism ]

Returning to fig. 5, the plug 3 may further include a liquid discharge flow path 37 in the plug main body 31. The liquid discharge flow path 37 extends in the axial direction of the rod main body 31 inside the rod main body 31. The liquid discharge channel 37 extends to the rear end surface (the end surface opposite to the front end surface connected to the plug 2) of the rod main body 31. Fig. 8 is a cross-sectional view of the core rod perpendicular to the axial direction at line C-C in the cooling zone 32. Referring to fig. 8, the drain passage 37 is formed in the center of the rod main body 31, and houses the coolant passage 34 and the gas passage 35 therein. However, the drain flow path 37 may not house the coolant flow path 34 and the gas flow path 35 therein.

The core rod 3 also includes 1 or more drain holes 371 in the cooling zone 32. When a plurality of drain holes 371 are formed, as shown in fig. 8, the plurality of drain holes 371 may be arranged in the circumferential direction of the rod main body 31, or may be arranged in the axial direction of the rod main body 31, although not shown. The drainage mechanism including the drainage flow paths 37 and the drainage holes 371 recovers a part of the coolant sprayed toward the inner surface portion of the hollow shell during the piercing-rolling and the elongating-rolling processes in the course of passing through the cooling zone 32.

The plug 3 of the piercing machine 10 according to the present embodiment may not have the drain flow path 37 and the drain hole 371.

[ method for manufacturing seamless Metal pipe Using piercing machine 10]

The piercing machine 10 having the above-described configuration cools the inner surface portion of the hollow shell 50 in the cooling zone 32 of the plug 3 with the coolant at the time of piercing-rolling or elongating, and suppresses the coolant from coming into contact with the inner surface portion of the hollow shell 50 in the contact suppression zone 33. In short, the piercing machine 10 actively cools the inner surface portion of the hollow shell 50 by using the coolant in the cooling zone 32, but does not contact the inner surface portion of the hollow shell 50 with the coolant as much as possible at the rear of the cooling zone 32. This suppresses variation in cooling time (length of cooling time) at each position in the longitudinal direction of the hollow shell 50, and reduces the temperature difference between the front end portion and the rear end portion of the hollow shell after piercing-rolling or elongating. This point is discussed in detail below.

Fig. 9 is a longitudinal sectional view of the hollow shell 50, plug, and plug 3 in piercing-rolling or elongating at the outlet side of the piercing machine 10.

Referring to fig. 9, during piercing-rolling or elongating, the inner surface cooling mechanism 340 of the mandrel bar 3 sprays the coolant from the coolant spray holes 341 in the cooling zone 32 to the outside of the bar body 31. Therefore, the inner surface portion in the cooling region 32 of the inner surface of the hollow shell in the piercing-rolling and the elongating-rolling is cooled by the cooling liquid. Here, the inner surface portion of the hollow shell 50 in the cooling zone 32 is an inner surface portion of the hollow shell 50 that overlaps with the cooling zone 32 when viewed in the radial direction of the hollow shell 50 (when viewed in the direction perpendicular to the axial direction of the plug 3).

In the piercing rolling or the elongating rolling, the inner surface intercepting means 350 of the mandrel bar 3 injects the compressed gas from the compressed gas injection holes 351 in the contact suppression region 33 to the outside of the bar main body 31. When the coolant injected from the coolant injection hole 341 of the cooling zone 32 flows to the rear of the cooling zone 32, the coolant is blown off by the injection of the compressed gas. As a result, the coolant can be prevented from contacting the inner surface portion of the hollow shell in the contact prevention region 33.

Specifically, as shown in fig. 10, in the contact suppression area 33, the compressed gas CG injected from the compressed gas injection holes 351 fills the gap between the outer surface of the plug 3 and the inner surface of the hollow shell 50, and as a result, as shown in fig. 11, the coolant C L accumulates in the gap between the outer surface of the plug 3 and the inner surface of the hollow shell 50 in the cooling area 32, and preferably, the coolant C L fills the gap between the outer surface of the plug 3 and the inner surface of the hollow shell 50, and the coolant C L is continuously injected from the coolant injection hole 341 in a state where the coolant C L is accumulated in the cooling area 32, and therefore, the accumulated coolant C L flows, and therefore, at the time of piercing or elongation rolling, the coolant in the cooling area 32 is injected into the inner surface of the hollow shell 50.

As described above, in the piercing mill 10 of the present embodiment, the inner surface portion of the hollow shell 50 is cooled in the cooling zone 32 of the plug 3 during piercing rolling or elongation rolling, and the contact suppression zone 33 suppresses the contact of the coolant with the inner surface portion of the hollow shell 50.

Here, as shown in fig. 12, it is assumed that the mandrel bar 3 is provided with the inner surface cooling means 340 but not provided with the inner surface intercepting means 350, in this case, there is no inner surface intercepting means 350, and therefore, the coolant C L flows out to the contact suppression region 33 located rearward of the cooling region 32, the coolant C L that flows out is particularly likely to accumulate below the mandrel bar 3 and on the inner surface of the hollow shell 50, and as the piercing rolling or the elongating rolling proceeds, the length of the hollow shell 50 extending rearward of the plug 2 increases, and therefore, the range in which the coolant C L is accumulated also changes, and therefore, the cooling time by the coolant C L is less likely to become constant at each position in the longitudinal direction of the hollow shell 50 during the piercing rolling or the elongating rolling, and as a result, the temperature is excessively lowered as compared with the rear end portion of the hollow shell 50 (the end portion passing through the plug 2 at the end of the rolling at the end of the hollow shell 50 at the time of the rolling.

In contrast, in the piercing mill 10 of the present embodiment, as shown in fig. 9, the inner surface intercepting means 350 is provided in the contact suppression region 33, and the compressed gas CG injected from the compressed gas injection holes 351 of the inner surface intercepting means 350 blows off the coolant C L entering the contact suppression region 33 or intercepts the coolant entering the contact suppression region 33, whereby the inner surface of the hollow shell 50 during piercing and elongating is cooled by the coolant C L in the cooling region 32, and the contact of the coolant C L is suppressed in the region (contact suppression region 33) located rearward of the cooling region 32, and as a result, the cooling time by the coolant C L is easily made constant at each position in the longitudinal direction of the hollow shell 50 during piercing and elongating, and the temperature difference between the leading end portion and the trailing end portion of the hollow shell 50 after piercing and elongating can be suppressed.

Further, as shown in fig. 9, the plug 3 has drain holes 371 in the cooling zone 32 at the tip end portion, and therefore, as shown in fig. 13, during piercing rolling or elongating rolling, part of the coolant C L that has cooled the inner surface of the hollow shell 50 is discharged to the drain flow path 37 via the drain holes 371, and the coolant C L discharged into the drain flow path 37 flows through the drain flow path 37 and is discharged to the outside of the plug 3 without coming into contact with the hollow shell 50, and further, the amount of the coolant C L that is newly discharged and reduced is replenished from the coolant ejection holes 341, and thus, if the plug has the drain holes 371, the coolant C L circulates, and therefore, the cooling of the inner surface of the hollow shell 50 in the cooling zone 32 is promoted, the drain holes 371 may be disposed at arbitrary positions in the cooling zone 32, and in order to promote the convection of the coolant C L, the drain holes 371 are preferably disposed at positions closer to the top 2 than the central portion in the axial direction of the cooling zone 32.

The drain hole 371 and the drain passage 37 may be omitted. However, the above-described effects can be obtained by forming the drain hole 371 and the drain flow path 37.

[ 2 nd embodiment ]

In the piercing machine according to the embodiment of fig. 2, which is different from fig. 6, fig. 14 is a cross-sectional view of the mandrel 3 at a line segment a-a in the cooling region 32 in fig. 5, which is perpendicular to the axial direction, fig. 14 is a cross-sectional view of the mandrel 3 in which the cooling liquid ejection holes 341 are formed at the tip end of the nozzle N34 and connected to the cooling liquid flow path 34, fig. 15 is an enlarged view of the cooling liquid ejection holes 341 when the rod body 31 shown in fig. 14 is viewed from the surface, and referring to fig. 14 and 15, the plurality of cooling liquid ejection holes 341 are oriented in the circumferential direction of the rod body 31 as viewed in the traveling direction of the hollow shell 50, and as shown in fig. 15, the ejection direction F34 of the cooling liquid ejection holes 341 opening at the tip end of the nozzle N34 intersects the axial direction X31 of the rod body 31 at an angle α and is oriented rearward of the rod body 31 as viewed in the radial direction of the rod body 31 (that is the side view of the rod body 31).

Fig. 16 is a cross-sectional view, different from fig. 7, of the mandrel 3 at a line segment B-B within the contact-suppressing region 33 in fig. 5, and is perpendicular to the axial direction, fig. 16 is a view of the compressed gas injection hole 351 formed at the tip of the nozzle N35 and connected to the gas flow path 35, fig. 17 is an enlarged view of the compressed gas injection hole 351 in a case where the rod main body 31 of the mandrel 3 is viewed from the surface, fig. 16 and 17 are a view in which a plurality of compressed gas injection holes 351 are directed in the circumferential direction of the rod main body 31 as viewed in the traveling direction of the hollow shell 50, and fig. 17 is a view in which the injection direction F35 of the compressed gas injection hole 351 opening at the tip of the nozzle N35 intersects the axial direction X31 of the rod main body 31 at an angle α and is directed rearward of the rod main body 31 as viewed in the radial direction of the rod.

[ formation of a rotational flow ]

Referring to fig. 18, in the piercing machine 10 of the present embodiment of embodiment 2, the inner surface cooling means 340 sprays the coolant from the coolant spray holes 341 along the circumferential direction of the rod main body 31 as viewed in the traveling direction of the hollow shell 50. Thereby, the coolant filled between the rod main body 31 and the inner surface of the hollow shell 50 in the cooling zone 32 is made to revolve in the circumferential direction of the rod main body 31, and a revolving flow SF34 is generated. The revolving flow SF34 flows rearward of the rod main body 31 while revolving around the rod main body 31. The swirl flow SF34 can suppress variation in the flow of the coolant in the circumferential direction of the rod main body 31. As a result, uneven cooling in the circumferential direction can be suppressed on the inner surface of the hollow shell 50.

In the present embodiment, the inner surface intercepting means 350 injects the compressed gas from the compressed gas injection holes 351 in the circumferential direction of the rod main body 31 as viewed in the traveling direction of the hollow shell 50. Thereby, the compressed gas filled between the rod main body 31 and the inner surface of the hollow shell 50 in the contact suppression region 33 is caused to revolve in the circumferential direction of the rod main body 31, and a revolving flow SF35 is generated. The revolving flow SF35 flows rearward of the rod main body 31 while revolving around the rod main body 31. Due to the swirling flow SF35, when the coolant constituting the swirling flow SF34 enters the contact suppression region 33 from the cooling region 32, the coolant is blown off rearward of the rod main body 31 by the swirling flow SF35 made of compressed gas. Therefore, in the contact suppression region 33, the coolant can be suppressed from contacting the inner surface of the hollow shell 50.

Fig. 19 is a sectional view of the piercing machine 10 illustrating the rotational flow SF34 of the coolant and the rotational flow SF35 of the compressed gas when the piercing machine 10 is viewed in the axial direction of the rod main body 31. As shown in fig. 19, the rotational flow SF34 of the coolant ejected from the plurality of coolant ejection holes 341 of the inner surface cooling means 340 is right-handed or left-handed as viewed in the traveling direction of the hollow shell 50. In addition, the revolving flow SF35 of the compressed gas injected from the plurality of compressed gas injection holes of the inner surface intercepting means 350 is right-handed or left-handed.

As shown in fig. 19, the rotating direction of the revolving flow SF35 of the compressed gas is preferably the same as the rotating direction of the revolving flow SF34 of the coolant in the inside surface cooling means 340. In this case, in the boundary between the cooling zone 32 and the contact suppression zone 33, the generation of turbulence caused by collision of the fluid (coolant, compressed gas) can be suppressed. Therefore, the coolant can be prevented from staying at the boundary between the cooling zone 32 and the contact prevention zone 33, and the coolant entering the contact prevention zone 33 can be blown off quickly toward the rear of the rod main body 31 by the swirl flow SF 35. As a result, it is possible to suppress cooling unevenness in the circumferential direction of the inner surface of the hollow shell 50 in the cooling zone 32, and also suppress the coolant from contacting the inner surface of the portion of the hollow shell 50 located rearward of the cooling zone 32.

Referring to fig. 18, the inner surface cooling means 340 may include a plurality of annularly arranged coolant injection hole groups 345 arranged in the axial direction of the rod main body 31. In this case, each of the annularly arranged coolant injection hole groups 345 includes a plurality of coolant injection holes 341 arranged in the circumferential direction of the rod body 31. Here, the distance by which the rotational flow SF34 of the coolant travels in the axial direction of the rod main body 31 to one turn around the rod main body 31 is defined as 1 rotation period distance DF 34. In this case, the distance between the adjacent annularly arranged coolant injection hole groups 345 in the axial direction of the rod main body 31 is preferably the same as the 1-revolution period distance DF 34. Here, "the same as the 1-revolution period distance DF 34" means that the distance between the adjacent annularly arranged coolant injection hole groups 345 is within the 1-revolution period distance DF34 ± 50%. Preferably, the distance between the adjacent annularly arranged coolant injection hole groups 345 is 1 revolution period distance DF34 ± 20%, more preferably 1 revolution period distance DF34 ± 10%.

In this case, when the swirl flow SF34 has traveled the 1-revolution period distance DF34, a new coolant is supplied from the next annularly arranged coolant injection hole group 345. Therefore, compared with the case where new coolant is supplied from the next annularly arranged coolant injection hole group 345 before the swirl flow SF34 reaches the 1-revolution period distance DF34, turbulence is less likely to occur in the swirl flow SF 34. Therefore, uneven cooling in the circumferential direction of the inner surface of the hollow shell 50 can be further suppressed.

Referring to fig. 18, the inner surface intercepting means 350 may include a plurality of annularly arranged gas injection hole groups 355 arranged in the axial direction of the rod main body 31, similarly to the inner surface cooling means 340. Each of the annularly arranged gas injection hole groups 355 includes a plurality of compressed gas injection holes 351 arranged in the circumferential direction of the rod main body 31. Here, the distance by which the revolving flow SF35 of the compressed gas travels in the axial direction of the rod main body 31 to one revolution around the rod main body 31 is defined as 1 revolution period distance DF 35. In this case, the distance between the adjacent annularly arranged gas injection hole groups 355 in the axial direction X31 of the rod main body 31 is preferably the same as the 1-revolution period distance DF 35. Here, "the same as the 1-revolution period distance DF 35" means that the distance between the adjacent annularly arranged gas injection hole groups 355 is within the 1-revolution period distance DF35 ± 50%. Preferably, the distance between the adjacent annularly arranged gas injection hole groups 355 is 1 revolution period distance DF35 ± 20%, and more preferably 1 revolution period distance DF35 ± 10%.

In this case, when the swirl flow SF35 has traveled the 1-revolution period distance DF35, a new compressed gas is supplied from the next annularly arranged gas injection hole group 355. Therefore, compared with the case where new compressed gas is supplied from the next annularly arranged gas injection hole group 355 before the swirl flow SF35 reaches the 1-revolution period distance DF35, turbulence is less likely to be generated in the swirl flow SF 35. In this case, the coolant flowing rearward from the cooling zone 32 can be blown off more quickly rearward of the rod main bodies 31 by the swirl flow SF35, and the coolant can be further suppressed from contacting the inner surface of the portion of the hollow shell 50 rearward of the cooling zone 32.

In the above-described embodiment, as shown in fig. 19, the direction of rotation of the swirling flow SF35 of the compressed gas generated by the inside surface intercepting means 350 is the same as the direction of rotation of the swirling flow SF34 of the coolant generated by the inside surface cooling means 340. However, the direction of the revolving flow SF35 of the compressed gas generated by the inside surface intercepting means 350 may be set to be different from (opposite to) the direction of the revolving flow SF34 of the coolant generated by the inside surface cooling means 340.

Even if the rotational direction of the revolving flow SF35 of the compressed gas generated by the inside surface intercepting means 350 is the same direction as the rotational direction of the revolving flow SF34 of the coolant generated by the inside surface cooling means 340, the angle α formed by the injection direction F34 of the coolant jet holes 341 shown in fig. 15 and the axial direction X31 of the rod main body 31 may be an angle different from the angle α formed by the injection direction F35 of the compressed gas injection holes 351 shown in fig. 17 and the axial direction X31 of the rod main body 31.

In the above-described embodiment, the inside surface cooling means 340 generates the rotational flow SF34 of the cooling liquid and the inside surface intercepting means 350 generates the rotational flow SF35 of the compressed gas, and in the piercing machine 10 according to embodiment 2, the above-described effects are obtained to some extent as long as at least the inside surface cooling means 340 generates the rotational flow SF34 of the cooling liquid. That is, in the piercing machine 10 according to embodiment 2, the inside surface cooling means 340 may generate the rotational flow SF34 of the cooling liquid, and the inside surface intercepting means 350 may inject the compressed gas, but the rotational flow SF35 is not generated. For example, the inner surface intercepting means 350 sprays the compressed gas in the radial direction of the wand main body 31. In this case, the inner surface intercepting means 350 does not form the revolving flow SF 35. However, in this case as well, the inner surface cooling mechanism 340 generates the swirl flow SF34, and therefore, in the cooling zone 32, the cooling unevenness in the inner surface circumferential direction of the hollow shell 50 can be suppressed to some extent.

In the above-described embodiment, when the rod main body 31 is viewed from the side (that is, when viewed from the direction perpendicular to the axial direction of the rod main body 31), the spray direction F34 of the coolant spray holes 341 of the inside surface cooling mechanism 340 intersects the axial direction X31 of the rod main body 31 and faces rearward of the rod main body 31. However, as shown in fig. 20, the spray direction F34 of the coolant spray hole 341 may be orthogonal to the axial direction X31 of the rod main body 31 and not directed rearward of the rod main body 31. In this case, the spiral flow SF34 can be generated to some extent. However, the spray direction F34 of the coolant spray holes 341 of the inside surface cooling mechanism 340 preferably intersects the axial direction X31 of the rod main body 31 and faces rearward of the rod main body 31. This is because the coolant easily travels toward the rear of the rod main body 31.

[ embodiment 3 ]

The inner surface intercepting means 350 may also inhibit the coolant from entering the contact inhibiting region 33 by means other than compressed gas.

Fig. 21 is a vertical cross-sectional view of the material near the inclined rolls in piercing-rolling or elongating in the piercing mill according to embodiment 3. Referring to fig. 21, in the present embodiment, the plug 3 does not include the gas flow path 35 and does not receive supply of gas from the gas supply device 8. The inner surface blocking mechanism 350 includes an inner surface blocking member 352 instead of the plurality of compressed gas injection holes 351.

The inner surface blocking member 352 is disposed at the rear end of the cooling region 32 so as to be adjacent to the cooling region 32. The inner surface intercepting member 352 extends in the circumferential direction of the rod main body 31, and thus, in a case where the mandrel 3 is viewed from the axial direction, the outer edge of the inner surface intercepting member 352 is circular. When the mandrel 3 is viewed in the direction perpendicular to the axial direction, the height H352 of the inner surface blocking member 352 is smaller than the difference H obtained by subtracting the radius of the mandrel at the position where the inner surface blocking member 352 is arranged from the maximum radius of the plug 2_2-3. That is, the height of the inner surface intercepting member is lower than the difference between the maximum radius of the plug and the radius of the rod main body at the position where the inner surface intercepting member is disposed. Therefore, the inner surface intercepting member does not come into contact with the inner surface of the hollow shell passed through the plug during piercing-rolling or elongating-rolling, and the inner surface of the hollow shell is not pressed down. Preferably, the height H352 of the inner surface intercepting member 352 is a difference H_2-3Above 1/2.

The raw material of the inner surface intercepting member 352 is, for example, glass wool. The raw material of the inner surface intercepting member 352 is not limited to glass wool. It is sufficient if the raw material has a melting point higher than the temperature of the inner surface of the hollow shell 50 in the piercing rolling or the elongating rolling. Preferably, the melting point of the raw material of the inner surface intercepting member 352 is 1100 ℃ or more.

The other configurations of the piercing machine of the present embodiment are the same as those of the piercing machine 10 of embodiment 1.

As shown in fig. 21, in the piercing machine of the present embodiment, the inner surface intercepting member 352 also inhibits the coolant C L from entering the contact inhibiting region 33 and physically intercepts the coolant C L in the cooling region 32 during piercing and rolling or elongation rolling, and therefore, the same effect as that of embodiment 1 is obtained.

The plug 3 shown in fig. 21 may include the gas flow path 35, and the inner surface blocking mechanism 350 may include a plurality of compressed gas injection holes 351 and an inner surface blocking member 352.

[ 4 th embodiment ]

In embodiments 1 to 3, the inner surface portion on the cooling zone 32 of the inner surface of the hollow shell 50 subjected to piercing-rolling or elongating is cooled. In the present embodiment, the outer surface portion of the hollow shell 50 of the cooling zone 32 is also cooled.

Fig. 22 is a vertical cross-sectional view of the material near the inclined rolls in piercing-rolling or elongating in the piercing mill according to embodiment 4.

Referring to fig. 22, the piercing machine 10 further includes an outer surface cooling mechanism 400, compared to the piercing machine 10 shown in fig. 9. The outer surface cooling mechanism 400 is disposed behind the plug 2 and around the mandrel 3.

Referring to fig. 22, the outer surface cooling mechanism 400 sprays a cooling fluid toward the outer surface portion of the hollow shell 50 during the piercing-rolling or the elongating-rolling in the cooling zone 32 to cool the hollow shell 50 in the cooling zone 32.

Fig. 23 is a view showing the outer surface cooling mechanism 400 when viewed in the traveling direction of the hollow shell 50 (that is, a front view of the outer surface cooling mechanism 400), referring to fig. 22 and 23, the outer surface cooling mechanism 400 includes an outer surface cooling upper member 400U, an outer surface cooling lower member 400D, an outer surface cooling left member 400L, and an outer surface cooling right member 400R.

[ Structure of outer surface Cooling Upper Member 400U ]

The outer surface cooling upper member 400U is disposed above the mandrel 3. The outer surface cooling upper member 400U includes a main body 402 and a plurality of cooling fluid upper spray holes 401U. The main body 402 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more cooling fluid paths inside through which the cooling fluid CF (see fig. 22) passes. In this example, a plurality of cooling fluid upper spray holes 401U are formed at the tips of the plurality of cooling fluid upper nozzles 403U. However, the cooling fluid upper injection holes 401U may be formed directly in the main body 402. In this example, a plurality of cooling fluid upper nozzles 403U arranged around the mandrel 3 are connected to the main body 402.

The plurality of cooling fluid upper injection holes 401U face the mandrel 3. When the pierced or elongated hollow shell 50 passes through the outer surface cooling mechanism 400, the plurality of cooling fluid upper injection holes 401U face the outer surface of the hollow shell 50. The plurality of cooling fluid upper injection holes 401U are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3. Preferably, the plurality of cooling fluid upper injection holes 401U are arranged at equal intervals around the mandrel 3. Referring to fig. 22, preferably, a plurality of cooling fluid upper injection holes 401U are also arranged in the axial direction of the mandrel 3.

[ Structure of outer surface-cooled lower Member 400D ]

Referring to fig. 23, the outer surface cooling lower member 400D is disposed below the mandrel 3. The outer surface cooling lower member 400D includes a main body 402 and a plurality of cooling fluid lower spray holes 401D. The main body 402 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more cooling fluid paths inside through which the cooling fluid CF passes. In this example, a plurality of cooling fluid lower spray holes 401D are formed at the tips of the plurality of cooling fluid lower nozzles 403D. However, the cooling fluid lower injection holes 401D may be formed directly in the body 402. In this example, a plurality of cooling fluid lower nozzles 403D arranged around the mandrel 3 are connected to the main body 402.

The plurality of cooling fluid lower injection holes 401D face the mandrel 3. When the pierced or elongated hollow shell 50 is passed through the outer surface cooling mechanism 400, the plurality of cooling fluid lower injection holes 401D face the outer surface of the hollow shell 50. The plurality of cooling fluid lower injection holes 401D are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3. Preferably, the plurality of cooling fluid lower injection holes 401D are arranged at equal intervals around the mandrel 3. Referring to fig. 22, preferably, a plurality of cooling fluid lower injection holes 401D are also arranged in the axial direction of the mandrel 3.

[ Structure in which the outer surface cools the left member 400L ]

Referring to fig. 23, the outer surface cooling left member 400L is disposed on the left side of the mandrel 3, the outer surface cooling left member 400L includes a main body 402 and a plurality of cooling fluid left spray holes 401L, the main body 402 is a tubular or plate-shaped shell that is curved in the circumferential direction of the mandrel 3, and has 1 or more cooling fluid paths inside for the cooling fluid CF to pass through, in this example, a plurality of cooling fluid left spray nozzles 403L arranged around the mandrel 3 are connected to the main body 402, and a plurality of cooling fluid left spray holes 401L are formed at the tips of the plurality of cooling fluid left spray nozzles 403L, however, the cooling fluid left spray holes 401L may be formed directly in the main body 402.

The plurality of cooling fluid left injection holes 401L face the plug 3, when the hollow shell 50 subjected to piercing-rolling or elongating is passed through the outer surface cooling mechanism 400, the plurality of cooling fluid left injection holes 401L face the outer surface of the hollow shell 50, the plurality of cooling fluid left injection holes 401L are located around the plug 3 and arranged in the circumferential direction of the plug 3, preferably, the plurality of cooling fluid left injection holes 401L are arranged at equal intervals around the plug 3, and preferably, a plurality of cooling fluid left injection holes 401L are also arranged in the axial direction of the plug 3.

[ Structure of outer surface-cooled Right Member 400R ]

Referring to fig. 23, the outer surface cooling right member 400R is disposed rightward of the plug 3. The outer surface cooling right member 400R includes a main body 402 and a plurality of cooling fluid right spray holes 401R. The main body 402 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more cooling fluid paths inside through which the cooling fluid CF passes. In this example, a plurality of cooling fluid right nozzles 403R arrayed around the mandrel 3 are connected to the main body 402, and a plurality of cooling fluid right spouting holes 401R are formed at the tips of the plurality of cooling fluid right nozzles 403R. However, the cooling fluid right injection hole 401R may be formed directly in the main body 402.

The plurality of cooling fluid right injection holes 401R face the mandrel 3. When the pierced or elongated hollow shell 50 passes through the outer surface cooling mechanism 400, the plurality of cooling fluid right injection holes 401R face the outer surface of the hollow shell 50. The plurality of cooling fluid right injection holes 401R are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3. Preferably, the plurality of cooling fluid right spray holes 401R are arranged at equal intervals around the mandrel 3. Preferably, a plurality of the cooling fluid right injection holes 401R are also arranged in the axial direction of the mandrel 3.

In fig. 23, the outer surface-cooled upper member 400U, the outer surface-cooled lower member 400D, the outer surface-cooled left member 400L, and the outer surface-cooled right member 400R are separate members independent of each other, however, as shown in fig. 24, the outer surface-cooled upper member 400U, the outer surface-cooled lower member 400D, the outer surface-cooled left member 400L, and the outer surface-cooled right member 400R may be connected.

In addition, either one of the outer surface-cooled upper member 400U, the outer surface-cooled lower member 400D, the outer surface-cooled left member 400L, and the outer surface-cooled right member 400R may be constituted by a plurality of members, or a part of adjacent outer surface-cooled members may be connected, in FIG. 25, the outer surface-cooled left member 400L is constituted by two members (400L U, 400L D), and the upper member 400L U of the outer surface-cooled left member 400L is connected to the outer surface-cooled upper member 400U, the lower member 400D of the outer surface-cooled left member 400L is connected to the outer surface-cooled lower member 400L D, and in addition, the outer surface-cooled right member 400R is constituted by two members (400RU, 400RD), and the upper member 400RU of the outer surface-cooled right member 400R is connected to the outer surface-cooled upper member 400U, and the lower member 400RD of the outer surface-cooled right member 400R is connected to the outer surface-cooled.

In short, the configuration of each of the outer surface cooling members (the outer surface cooling upper member 400U, the outer surface cooling lower member 400D, the outer surface cooling left member 400L, and the outer surface cooling right member 400R) may be provided with a plurality of members, or may be formed partially or entirely integrally with other outer surface cooling members, as long as the outer surface cooling upper member 400U sprays the cooling fluid CF toward the upper portion of the outer surface of the hollow shell 50, the outer surface cooling lower member 400D sprays the cooling fluid CF toward the lower portion of the outer surface of the hollow shell 50, the outer surface cooling left member 400L sprays the cooling fluid CF toward the left portion of the outer surface of the hollow shell 50, and the outer surface cooling right member 400R sprays the cooling fluid CF toward the right portion of the outer surface of the hollow shell 50, and the respective outer surface cooling members (the outer surface cooling upper member 400U, the outer surface cooling lower member 400D, the outer surface cooling left member 400L, and the outer surface cooling.

[ operation of the outer surface cooling mechanism 400 ]

The outer surface cooling mechanism 400 having the above-described structure sprays the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 passing through the inclined rolls 1 in the cooling zone 32 during piercing or elongating by the piercing mill 10, and cools the hollow shell 50 in the cooling zone 32 of the specific length L32, more specifically, when viewed in the traveling direction of the hollow shell 50, the outer surface cooling upper member 400U sprays the cooling fluid CF toward the upper portion of the outer surface of the hollow shell 50 in the cooling zone 32, the outer surface cooling lower member 400D sprays the cooling fluid CF toward the lower portion of the outer surface of the hollow shell 50 in the cooling zone 32, the outer surface cooling left member 400L sprays the cooling fluid CF toward the left portion of the outer surface of the hollow shell 50 in the cooling zone 32, the outer surface cooling right member 400R sprays the cooling fluid CF toward the right portion of the outer surface of the hollow shell 50 in the cooling zone 32, and the difference in the axial direction between the outer surface of the hollow shell 50 in the piercing and the piercing mill 50 is suppressed, and the temperature difference between the outer surface of the hollow shell 50 after piercing and elongating by the piercing mill 10 is explained.

The piercing mill 10 performs piercing-rolling or elongating-rolling on the raw material 20 to manufacture the hollow shell 50. When the piercing machine 10 is a piercing-rolling mill, the piercing machine 10 pierces and rolls a round billet as the material 20 to form the hollow shell 50. When the piercing machine 10 is an elongation rolling mill, the piercing machine 10 elongates and rolls a hollow shell as the material 20 to form the hollow shell 50.

When piercing-rolling or elongating is performed by the piercing mill 10, referring to fig. 22, the outer surface cooling mechanism 400 receives a supply of the cooling fluid CF from the fluid supply source 800. Here, as described above, the cooling fluid CF is a gas and/or a liquid. The cooling fluid CF may be only a gas or only a liquid. The cooling fluid CF may also be a mixed fluid of gas and liquid.

The fluid supply source 800 includes a reservoir 801 for the cooling fluid CF and a supply mechanism 802 for supplying the cooling fluid CF. When the cooling fluid CF is a gas, the supply mechanism 802 includes, for example, a valve 803 for starting or stopping supply and a fluid drive source (gas pressure adjusting device) 804 for supplying a fluid (gas). When the cooling fluid CF is a liquid, the supply mechanism 802 includes, for example, a valve 803 for starting or stopping supply and a fluid drive source (pump) 804 for supplying a fluid (liquid). When the cooling fluid CF is a gas or a liquid, the supply mechanism 802 includes a mechanism for supplying a gas and a mechanism for supplying a liquid. The fluid supply source 800 is not limited to the above configuration. The structure is not limited as long as the cooling fluid can be supplied to the outer surface cooling mechanism 400, and a well-known structure may be used.

The cooling fluid CF supplied from the fluid supply source 800 to the outer surface cooling mechanism 400 cools the cooling fluid path in the main body 402 of the upper member 400U through the outer surface of the outer surface cooling mechanism 400, reaches the respective cooling fluid upper injection holes 401U. the cooling fluid CF also passes through the cooling fluid path in the main body 402 of the outer surface cooling lower member 400D, reaches the respective cooling fluid lower injection holes 401D. the cooling fluid CF also passes through the cooling fluid path in the main body 402 of the outer surface cooling left member 400L, reaches the respective cooling fluid left injection holes 401L. the cooling fluid CF also sprays the cooling fluid CF through the cooling fluid path in the main body 402 of the outer surface cooling right member 400R, reaches the respective cooling fluid right injection holes 401R. and the outer surface cooling mechanism 400 cools the hollow shell 50 by spraying the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 which is pierced or extended rolled through the rear end of the plug 2 and enters the cooling region 32.

At this time, as shown in fig. 22, the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper, lower, left, and right portions of the outer surface of the hollow shell 50 within the range of the cooling zone 32 having a specific length along the axial direction of the plug 3 to cool the hollow shell 50. The cooling region 32 means a range where the cooling fluid CF is sprayed by the outer surface cooling mechanism 400. The cooling zone 32 is a range that surrounds the entire circumference of the plug 3 when viewed along the traveling direction of the hollow shell 50 (when the piercing machine 10 is viewed from the front to the rear). That is, the cooling zone 32 is a cylindrical range extending in the axial direction of the plug 3.

In the case where the outer surface cooling mechanism 400 includes a plurality of cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R), the plurality of cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R) are arranged in the cooling region 32.

As described above, in the present embodiment, the piercing machine 10 uses the outer surface cooling mechanism 400 disposed around the mandrel bar 3 behind the plug 2, and the inner surface cooling mechanism 340 cools the inner surface of the hollow shell 50 in the cooling zone 32 disposed behind the plug 2 and having the specific length L, and further, the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 as viewed in the traveling direction of the hollow shell 50 to cool the hollow shell 50 in the cooling zone 32, and at this time, the outer surface portion (the upper portion, the lower portion, the left portion, and the right portion) of the hollow shell 50 during traveling in the cooling zone 32 is in contact with the cooling fluid CF to cool the hollow shell 50, and on the other hand, the outer surface portion of the hollow shell 50 is hard to be in contact with the cooling fluid CF outside the range of the cooling zone 32 (the front of the cooling zone 32 and the rear of the cooling zone 32), and the outer surface portion of the hollow shell 50 is hard to be in contact with the cooling fluid CF, and therefore, the cooling mechanism can suppress the temperature difference between the outer surface of the cooling fluid CF and the cooling zone 32 after the cooling fluid CF contacts the outer surface of the cooling zone 32, and the cooling fluid CF 32, and the cooling fluid C can suppress the cooling fluid C, and the cooling fluid can suppress the cooling fluid can reduce the temperature difference between the outer surface of the cooling zone 50.

[ method for manufacturing seamless Metal pipe in embodiment 4 ]

In embodiment 4, at the time of piercing-rolling or elongation-rolling, the inner surface cooling mechanism 340 cools the inner surface portion of the hollow shell 50 in the cooling zone 32, and the outer surface cooling mechanism 400 cools the outer surface portion of the hollow shell 50 in the cooling zone. Therefore, the cooling of the hollow shell 50 immediately after the piercing-rolling or the elongating-rolling is completed (i.e., immediately after passing through the plug 2) can be promoted. In particular, in the case of manufacturing a seamless metal pipe having a thick wall (for example, a wall thickness of 30mm or more), an effective effect can be obtained.

In the above-described cooling step, in the rolling step (piercing rolling or elongating rolling), the inner surface cooling mechanism 340 cools the inner surface portion of the hollow shell 50 in the cooling zone 32, and sprays the cooling fluid CF toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 in the course of traveling in the cooling zone 32, as viewed in the traveling direction of the hollow shell 50, to cool the hollow shell 50 in the cooling zone 32. As a result, as described above, the temperature variation in the axial direction of the hollow shell 50 after cooling can be reduced, and the temperature difference between the front end portion and the rear end portion of the hollow shell 50 can be reduced.

In fig. 22 to 25, the outer surface cooling mechanism 400 sprays the cooling fluid CF from the plurality of cooling fluid injection holes 401 (the cooling fluid upper injection hole 401U, the cooling fluid lower injection hole 401D, the cooling fluid left injection hole 401L, and the cooling fluid right injection hole 401R) to cool the outer surface portion of the hollow shell 50 of the cooling zone 32. the shapes of the cooling fluid injection holes 401 (the cooling fluid upper injection hole 401U, the cooling fluid lower injection hole 401D, the cooling fluid left injection hole 401L, and the cooling fluid right injection hole 401R) are not particularly limited, and the cooling fluid injection holes 401 (the cooling fluid upper injection hole 401U, the cooling fluid lower injection hole 401D, the cooling fluid left injection hole 401L, and the cooling fluid right injection hole 401R) may be either circular or elliptical or rectangular in shape.

In fig. 22, a plurality of cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R) are arranged in the axial direction of the mandrel 3, but a plurality of cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R) may not be arranged in the axial direction of the mandrel 3. in fig. 23 to 25, cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R) may be arranged at equal intervals around the mandrel 3, but cooling fluid injection holes 401 (cooling fluid upper injection hole 401U, cooling fluid lower injection hole 401D, cooling fluid left injection hole 401L, and cooling fluid right injection hole 401R) may be arranged at unequal intervals around the mandrel 3.

[ 5 th embodiment ]

Fig. 26 is a diagram showing the structure of the exit side of the inclined roll 1 of the piercing mill 10 according to embodiment 5. Referring to fig. 26, the piercing machine 10 according to embodiment 5 is provided with a new front catching mechanism 600 compared to the piercing machine 10 according to embodiment 4. The other configurations of the piercing machine 10 according to embodiment 5 are the same as those of the piercing machine 10 according to embodiment 4.

[ front intercept mechanism 600]

The front catching mechanism 600 is located behind the plug 2 and is arranged around the mandrel 3 at a position forward of the outer surface cooling mechanism 400. The front interception mechanism 600 includes the following mechanisms: when the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32 to cool the hollow shell in the cooling zone 32, the mechanism intercepts the flow of the cooling fluid to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

Fig. 27 is a view of the forward catching mechanism 600 as viewed along the traveling direction of the hollow shell 50 (a view from the entrance side to the exit side of the inclined rolls 1). Referring to fig. 26 and 27, the front catching mechanism 600 is disposed around the mandrel bar 3 as viewed in the traveling direction of the hollow shell 50. In the piercing-rolling or the elongating, as shown in fig. 27, the front holding means 600 is disposed around the hollow shell 50 subjected to the piercing-rolling or the elongating.

Referring to fig. 27, the front intercepting mechanism 600 includes a front intercepting upper member 600U, a front intercepting lower member 600D, a front intercepting left member 600L, and a front intercepting right member 600R as viewed in the traveling direction of the hollow shell 50.

[ Structure of front intercept upper Member 600U ]

The front dam upper member 600U is disposed above the mandrel 3. The front intercepting upper member 600U includes a main body 602 and a plurality of front intercepting fluid upper injection holes 601U. The main body 602 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the front intercepting fluid FF (see fig. 26) passes. In this example, a plurality of front intercepted fluid upper injection holes 601U are formed at the tips of a plurality of front intercepted fluid upper nozzles 603U. However, the front intercepting fluid upper injection hole 601U may be directly formed at the main body 602. In this example, a plurality of front fluid intercepting upper nozzles 603U arranged around the mandrel 3 are connected to the main body 602.

When the pierced or elongated hollow shell 50 passes through the outer surface cooling mechanism 400, the plurality of front fluid intercepting upper injection holes 601U of the front fluid intercepting upper member 600U face the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32. The plurality of front fluid intercepting upper injection holes 601U are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of forward intercepting fluid upper injection holes 601U are arranged at equal intervals around the mandrel. Further, the plurality of forward intercepting fluid upper injection holes 601U may be arranged in parallel in the axial direction of the mandrel 3.

In piercing or elongating, when the hollow shell 50 is cooled in the cooling zone 32 by the outer surface cooling mechanism 400, the front intercepting upper member 600U sprays the front intercepting fluid FF from the plurality of front intercepting fluid upper injection holes 601U toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the upper portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

[ Structure of front intercepting lower Member 600D ]

The front lower holding member 600D is disposed below the mandrel 3. The front intercepting lower member 600D includes a main body 602 and a plurality of front intercepting fluid lower injection holes 601D. The main body 602 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the front intercepting fluid FF passes. In this example, a plurality of front intercepting fluid lower injection holes 601D are formed at the tips of the plurality of front intercepting fluid lower nozzles 603D. However, the front intercepting fluid lower injection hole 601D may be directly formed at the main body 602. In this example, a plurality of front fluid intercepting lower nozzles 603D arranged around the mandrel 3 are connected to the main body 602.

When the pierced or elongated hollow shell 50 passes through the outer surface cooling mechanism 400, the plurality of front intercepting fluid lower injection holes 601D of the front intercepting member 600D face the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32. The plurality of forward intercepting fluid lower injection holes 601D are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of front intercepting fluid lower injection holes 601D are arranged at equal intervals around the mandrel. Further, the plurality of front damming fluid lower injection holes 601D may be arranged in parallel in the axial direction of the mandrel 3.

In piercing or elongating, when the hollow shell 50 is cooled in the cooling zone 32 by the outer surface cooling mechanism 400, the front intercepting lower member 600D sprays the front intercepting fluid FF from the plurality of front intercepting fluid lower injection holes 601D toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the lower portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

[ Structure of front intercept left member 600L ]

The front intercepting left member 600L is disposed on the left of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. the front intercepting left member 600L includes a main body 602 and a plurality of front intercepting fluid left injection holes 601L. the main body 602 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3 and has 1 or more fluid paths inside through which the front intercepting fluid FF passes.

When the hollow shell 50 subjected to piercing-rolling or elongating passes through the outer surface cooling mechanism 400, the plurality of front fluid intercepting left injection holes 601L of the front fluid intercepting left member 600L face the left portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32, the plurality of front fluid intercepting left injection holes 601L are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50, preferably, the plurality of front fluid intercepting left injection holes 601L are arranged at equal intervals around the mandrel, and the plurality of front fluid intercepting left injection holes 601L may also be arranged in parallel in the axial direction of the mandrel 3.

During piercing or elongating, when the hollow shell 50 is cooled in the cooling zone 32 by the outer surface cooling mechanism 400, the front intercepting left member 600L jets the front intercepting fluid FF from the plurality of front intercepting fluid left injection holes 601L toward the left portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the left portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

[ Structure of front intercept right Member 600R ]

The front interception right member 600R is disposed on the right side of the plug 3 as viewed in the traveling direction of the hollow shell 50. The front intercepting right member 600R includes a main body 602 and a plurality of front intercepting fluid right injection holes 601R. The main body 602 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the front intercepting fluid FF passes. In this example, the plurality of right front interceptor fluid injection holes 601R are formed at the tips of the plurality of right front interceptor fluid nozzles 603R. However, the front intercepting fluid right injection hole 601R may be directly formed at the main body 602. In this example, a plurality of right front fluid intercepting nozzles 603R arranged around the mandrel 3 are connected to the main body 602.

When the pierced or elongated hollow shell 50 passes through the outer surface cooling mechanism 400, the plurality of right front fluid intercepting injection holes 601R of the right front intercepting member 600R face the right portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32. The plurality of front intercepted fluid right injection holes 601R are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of right front damming fluid injection holes 601R are arranged at equal intervals around the mandrel. Further, the plurality of right front damming fluid injection holes 601R may be arranged in parallel in the axial direction of the mandrel 3.

During piercing or elongating, when the hollow shell 50 is cooled in the cooling zone 32 by the outer surface cooling mechanism 400, the front intercepting right member 600R sprays the front intercepting fluid FF from the plurality of front intercepting fluid right injection holes 601R toward the right portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the right portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

[ operation of the front catch mechanism 600]

In the piercing-rolling or the elongating, the outer surface cooling mechanism 400 sprays the cooling fluid CF to the outer surface portion of the hollow shell 50 in the cooling zone 32 out of the outer surface of the hollow shell 50 subjected to the piercing-rolling or the elongating to cool the hollow shell 50. At this time, the following may occur: the cooling fluid CF injected to the outer surface portion of the hollow shell 50 in the cooling zone 32 contacts the outer surface portion of the hollow shell 50, and then flows forward of the outer surface portion to contact the outer surface portion of the hollow shell 50 forward of the cooling zone 32. As long as the occurrence frequency of such contact of the cooling fluid CF with the outer surface portion other than the cooling region 32 becomes high, the temperature distribution in the axial direction of the hollow shell 50 may be deviated.

Therefore, in the present embodiment, the front intercepting means 600 suppresses the cooling fluid CF flowing on the outer surface from coming into contact with the outer surface portion of the hollow shell 50 in front of the cooling zone 32 after coming into contact with the outer surface portion of the hollow shell 50 in the cooling zone 32 at the time of piercing-rolling or elongating.

Specifically, when the outer surface cooling means 400 sprays the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32 to cool the hollow shell in the cooling zone 32, the front intercepting upper member 600U sprays the front intercepting fluid FF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32 as viewed in the traveling direction of the hollow shell 50, and a dam (retaining wall) composed of the front intercepting fluid FF is formed on the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32, and a dam (retaining wall) composed of the front intercepting fluid FF is formed on the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32, as the front intercepting lower member 600D sprays the front intercepting fluid FF toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32, and the front fluid FF (retaining wall) sprays the fluid FF onto the outer surface of the cooling zone 32 to the cooling zone 32, and the cooling zone outer surface of the cooling zone 50 is formed by spraying the front fluid FF (retaining wall) onto the cooling zone 32, and the cooling zone 32, the cooling zone 50 is formed by spraying the fluid FF (fluid FF) onto the cooling zone 32, and the cooling zone 32.

Fig. 28 is a sectional view of the front intercepting upper member 600U parallel to the traveling direction of the hollow shell 50, fig. 29 is a sectional view of the front intercepting lower member 600D parallel to the traveling direction of the hollow shell 50, fig. 30 is a sectional view of the front intercepting left member 600L parallel to the traveling direction of the hollow shell 50, and fig. 31 is a sectional view of the front intercepting right member 600R parallel to the traveling direction of the hollow shell 50.

Referring to fig. 28, it is preferable that the front intercepting upper member 600U sprays the front intercepting fluid FF. obliquely rearward from the front intercepting fluid upper injection holes 601U toward an upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 referring to fig. 29, it is preferable that the front intercepting lower member 600D sprays the front intercepting fluid FF. obliquely rearward from the front intercepting fluid lower injection holes 601D toward a lower portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 referring to fig. 30, it is preferable that the front intercepting left member 600L sprays the front intercepting fluid FF. obliquely rearward from the front intercepting fluid left injection holes 601L toward a left portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 referring to fig. 31, and it is preferable that the front intercepting right member 600R sprays the front intercepting fluid FF obliquely rearward from the front fluid right portion 601R toward a right portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone.

In fig. 28 to 31, the upper front intercepting member 600U forms a weir (a retaining wall) for intercepting the fluid FF from above the hollow shell 50 toward the upper portion of the outer surface of the hollow shell 50, similarly, the lower front intercepting member 600D forms a weir (a retaining wall) for intercepting the fluid FF from below the hollow shell 50 toward the lower portion of the outer surface of the hollow shell 50, similarly, the left front intercepting member 600L forms a weir (a retaining wall) for intercepting the fluid FF from left of the hollow shell 50 toward left of the outer surface of the hollow shell 50, similarly, the right front intercepting member 600R forms a weir (a retaining wall) for intercepting the fluid FF from right of the hollow shell 50 toward right of the outer surface of the hollow shell 50, these weirs are in contact with the outer surface portion of the hollow shell 50 in the cooling region 32 to facilitate the splashing of the cooling fluid cf flying forward of the cooling region 32, and the weir (the fluid FF intercepting region 32 is in contact with the outer surface portion of the cooling region 32, and the cooling fluid FF flows back into the cooling region 32 in front of the cooling region 32, thus, the cooling fluid FF flows back into the region 32, and the cooling fluid FF flows back into the cooling region.

Further, each of the front dam members (the upper front dam member 600U, the lower front dam member 600D, the left front dam member 600L, and the right front dam member 600R) may be configured to eject the front dam fluid FF. obliquely backward from each of the upper front dam fluid injection holes (601U, 601D, 601L, 601R) toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 located in the vicinity of the inlet side of the cooling zone 32, for example, the upper front dam member 600U may eject the front dam fluid FF. in the radial direction of the plug 3 from the upper front dam fluid injection hole 601U, the lower front dam member 600D may eject the front dam fluid FF. in the radial direction of the plug 3 from the lower front dam fluid injection hole 601D, the left front dam fluid 600R may eject the front dam fluid FF. in the radial direction of the plug 3 from the left front dam fluid injection hole 601D, or the front dam fluid FF in the radial direction of the plug 3 from the right front dam fluid injection hole 601R.

The front intercepting fluid FF is a gas and/or a liquid. That is, as the front intercepting fluid FF, either gas or liquid or both of gas and liquid may be used. Here, the gas is, for example, air or an inert gas. The inert gas is, for example, argon or nitrogen. In the case where gas is used as the front intercepting fluid FF, only air may be used, only inert gas may be used, or both air and inert gas may be used. As the inert gas, only 1 kind of inert gas (for example, only argon gas, only nitrogen gas) may be used, or plural kinds of inert gases may be mixed and used. In case a liquid is used as the front intercepting fluid FF, the liquid is for example water, oil, preferably water.

The front dam mechanism 600 receives supply of the front dam fluid FF from a fluid supply source (not shown), the fluid supply source has the same configuration as the fluid supply source 800, for example, the front dam fluid FF supplied from the fluid supply source is injected from the front dam fluid injection holes (the front dam fluid upper injection hole 601U, the front dam fluid lower injection hole 601D, the front dam fluid left injection hole 601L, and the front dam fluid right injection hole 601R) through a fluid path in the main body 602 of the front dam mechanism 600.

The configuration of the front barrier mechanism 600 is not limited to fig. 26 to 31, for example, in fig. 27, the upper front barrier member 600U, the lower front barrier member 600D, the left front barrier member 600L, and the right front barrier member 600R are independent members, however, as shown in fig. 32, the upper front barrier member 600U, the lower front barrier member 600D, the left front barrier member 600L, and the right front barrier member 600R may be integrally connected.

In addition, either one of the front intercepting upper member 600U, the front intercepting lower member 600D, the front intercepting left member 600L, and the front intercepting right member 600R may be configured of a plurality of members, or may be connected to a portion of the adjacent front intercepting member, in fig. 33, the front intercepting left member 600L is configured of two members (600L U, 600L D), and the upper member 600L U of the front intercepting left member 600L is connected to the front intercepting upper member 600U, the lower member 600D of the front intercepting left member 600L is connected to the front intercepting lower member 600L D, and in addition, the front intercepting right member 600R is configured of two members (600RU, 600RD), and the upper member 600RU of the front intercepting right member 600R is connected to the front intercepting upper member 600U, and the lower member 600RD of the front intercepting right member 600R is connected to the front intercepting lower member 600D.

In short, each of the front dam members (the upper front dam member 600U, the lower front dam member 600D, the left front dam member 600L, the right front dam member 600R) may be provided with a plurality of members, or may be formed partially or entirely integrally with the other front dam members, and each of the front dam members (the upper front dam member 600U, the lower front dam member 600D, the left front dam member 600R, the left front dam member 600L, the right front dam member 600R, the front dam member 600D, the left front dam member 600 FF, the right front dam member 600R, the left front dam member 600 f, the right front dam member 600R, the front dam member 600L) is not particularly limited as long as the upper front dam member 600U sprays the front dam fluid FF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32, the lower front dam member 600D, the left front dam member 600R sprays the front dam fluid FF toward the lower front dam member 600R toward the outer surface of the hollow shell 50 located in the vicinity of the entrance side of the cooling zone 32.

As shown in fig. 34, the front intercepting means 600 may include a front intercepting upper member 600U, a front intercepting left member 600L, and a front intercepting right member 600R, and may not include a front intercepting lower member 600D. the cooling fluid CF injected from the outer surface cooling means 400 toward the lower portion of the outer surface of the hollow shell 50 in the cooling zone 32 is likely to directly fall down toward the lower portion of the hollow shell 50 due to gravity after contacting the lower portion of the outer surface of the hollow shell 50. therefore, the cooling fluid CF injected from the outer surface cooling means 400 toward the lower portion of the outer surface of the hollow shell 50 in the cooling zone 32 is less likely to flow toward the lower portion of the outer surface of the hollow shell in front of the cooling zone 32. as shown in fig. 35, the front intercepting means 600 may not include the front intercepting lower member 600D. as shown in fig. 35, the front intercepting means 600 may include the front intercepting upper member 600U, the front intercepting left member 600L, and the front intercepting right member 600R may be disposed closer to the central axis of the mandrel bar than the central axis of the front intercepting upper member 600, and the central axis of the mandrel bar 3 is more likely to be disposed closer to the central axis of the mandrel bar 3 than the central axis of the front mandrel bar of the hollow shell 50.

The front catch mechanism 600 may have a structure different from that of fig. 26 to 35. For example, as shown in fig. 36 and 37, the front intercepting mechanism 600 may also use a plurality of intercepting members 604. In this case, as shown in fig. 36, the front intercepting means 600 includes a plurality of intercepting members 604 arranged around the mandrel bar 3 as viewed in the traveling direction of the hollow shell 50. The plurality of catching members 604 are rollers such as shown in fig. 36. In the case where the intercepting member 604 is a roller, as shown in fig. 36 and 37, it is preferable that the roller surface of the intercepting member 604 is curved so that the roller surface of the intercepting member 604 is in contact with the outer surface of the hollow shell 50. The catching member 604 is movable in the radial direction of the mandrel 3 by a movement mechanism not shown. The moving mechanism is, for example, a cylinder. The cylinder may be hydraulic, pneumatic, or electric.

During piercing and elongating, the plurality of catching members 604 are moved in the radial direction toward the outer surface of the hollow shell 50 as the hollow shell 50 passes through the front catching mechanism 600. The inner surfaces of the plurality of holding members 604 are disposed near the outer surface of the hollow shell 50 (fig. 37). Thus, when the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32, the plurality of dam members 604 form a weir (a protection wall). Therefore, the front intercepting mechanism 600 intercepts the flow of the cooling fluid to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 before entering the cooling zone 32.

In this manner, the front intercepting means 600 may be configured without using the front intercepting fluid FF. The front intercepting means 600 is not particularly limited as long as it has a means for intercepting the flow of the cooling fluid to the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 before entering the cooling zone 32 when the outer surface cooling means 400 cools the hollow shell 50.

[ 6 th embodiment ]

Fig. 38 is a diagram showing the structure of the exit side of the inclined roll 1 of the piercing mill 10 according to embodiment 6. Referring to fig. 38, the piercing machine 10 according to embodiment 6 is provided with a new rear catching mechanism 500, compared to the piercing machine 10 according to embodiment 1. The other configurations of the piercing machine 10 according to embodiment 6 are the same as those of the piercing machine 10 according to embodiment 4.

[ rear catch mechanism 500]

The rear catching mechanism 500 is disposed around the mandrel 3 behind the outer surface cooling mechanism 400. The rear interception mechanism 500 includes the following mechanisms: when the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32 to cool the hollow shell 50 in the cooling zone 32, the mechanism intercepts the flow of the cooling fluid to the upper portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

Fig. 39 is a view of the rear catching mechanism 500 as viewed along the traveling direction of the hollow shell 50 (a view from the entrance side to the exit side of the inclined rolls 1). Referring to fig. 38 and 39, the rear catching mechanism 500 is disposed behind the outer surface cooling mechanism 400 and around the mandrel bar 3 as viewed in the traveling direction of the hollow shell 50. In the piercing-rolling or the elongating, as shown in fig. 39, the back check mechanism 500 is disposed around the hollow shell 50 subjected to the piercing-rolling or the elongating.

Referring to fig. 39, the back catching mechanism 500 includes a back catching upper member 500U, a back catching lower member 500D, a back catching left member 500L, and a back catching right member 500R as viewed in the traveling direction of the hollow shell 50.

[ Structure of rear interception upper Member 500U ]

The rear catcher upper member 500U is disposed above the mandrel 3. The rear intercepting upper member 500U includes a main body 502 and a plurality of rear intercepting fluid upper spraying holes 501U. The main body 502 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the backward intercepting fluid BF (see fig. 38) passes. In this example, a plurality of upper backward intercepting fluid ejecting holes 501U are formed at the tips of the plurality of upper backward intercepting fluid ejecting nozzles 503U. However, the rear intercepting fluid upper injection holes 501U may be formed directly in the main body 502. In this example, a plurality of rear fluid intercepting upper nozzles 503U arranged around the mandrel 3 are connected to the main body 502.

When the pierced or elongated hollow shell 50 passes through the back dam mechanism 500, the plurality of back dam fluid upper injection holes 501U of the back dam upper member 500U face the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32. The plurality of rear intercepted fluid upper injection holes 501U are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of upper backward intercepting fluid injection holes 501U are arranged at equal intervals around the mandrel 3. Further, the plurality of backward intercepting fluid upper injection holes 501U may be arranged in parallel in the axial direction of the mandrel 3.

In piercing or elongating, when the outer surface cooling mechanism 400 cools the hollow shell 50 in the cooling zone 32, the backward intercepting upper member 500U sprays the backward intercepting fluid BF from the plurality of backward intercepting fluid upper injection holes 501U toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the upper portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

[ Structure of rear intercepting lower Member 500D ]

The rear interception lower member 500D is disposed below the plug 3. The rear intercepting lower member 500D includes a main body 502 and a plurality of rear intercepting fluid lower spraying holes 501D. The main body 502 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the backward intercepting fluid BF passes. In this example, a plurality of rear intercepting fluid lower ejecting holes 501D are formed at the tips of the plurality of rear intercepting fluid lower nozzles 503D. However, the rear intercepting fluid lower injection hole 501D may be directly formed at the main body 502. In this example, a plurality of rear interception fluid lower nozzles 503D arranged around the mandrel 3 are connected to the main body 502.

When the pierced or elongated hollow shell 50 passes through the backward intercepting means 500, the plurality of backward intercepting fluid lower injection holes 501D of the backward intercepting member 500D are directed toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32. The plurality of rear intercepting fluid lower injection holes 501D are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of backward intercepting fluid lower injection holes 501D are arranged at equal intervals around the mandrel 3. Further, the plurality of backward intercepting fluid lower injection holes 501D may be arranged in parallel in the axial direction of the mandrel 3.

In piercing or elongating, when the outer surface cooling mechanism 400 cools the hollow shell 50 in the cooling zone 32, the backward intercepting member 500D sprays the backward intercepting fluid BF from the plurality of backward intercepting fluid lower spraying holes 501D toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the lower portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

[ Structure of rear intercepting left Member 500L ]

The left rear intercepting member 500L is disposed to the left of the mandrel 3 as viewed in the traveling direction of the hollow shell 50. the left rear intercepting member 500L includes a main body 502 and a plurality of left rear intercepting fluid ejecting holes 501L. the main body 502 is a tubular or plate-like shell curved in the circumferential direction of the mandrel 3 and has 1 or more fluid paths inside through which the rear intercepting fluid BF passes.

When the hollow shell 50 subjected to piercing-rolling or elongating passes through the rear intercepting means 500, the plurality of rear intercepted fluid left injection holes 501L of the rear intercepting left member 500L face the left portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32, the plurality of rear intercepted fluid left injection holes 501L are located around the mandrel 3 and arranged in the circumferential direction of the mandrel 3 as viewed in the traveling direction of the hollow shell 50, preferably, the plurality of rear intercepted fluid left injection holes 501L are arranged at equal intervals around the mandrel 3, and the plurality of rear intercepted fluid left injection holes 501L may also be arranged in parallel in the axial direction of the mandrel 3.

In piercing or elongating, when the outer surface cooling mechanism 400 cools the hollow shell 50 in the cooling zone 32, the rear intercepting left member 500L jets the rear intercepting fluid BF from the plurality of rear intercepting fluid left injection holes 501L toward the left portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32 and intercepts the flow of the cooling fluid CF toward the left portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

[ Structure of rear intercept right Member 500R ]

The rear interception right member 500R is disposed on the right side of the plug 3 as viewed in the traveling direction of the hollow shell 50. The rear intercepting right member 500R includes a main body 502 and a plurality of rear intercepting fluid right spraying holes 501R. The main body 502 is a tubular or plate-shaped housing curved in the circumferential direction of the mandrel 3, and has 1 or more fluid paths inside through which the backward intercepting fluid BF passes. In this example, a plurality of rear intercepting fluid right injection holes 501R are formed at the tips of the plurality of rear intercepting fluid right nozzles 503R. However, the rear intercepting fluid right injection hole 501R may be formed directly in the main body 502. In this example, a plurality of rear fluid intercepting right nozzles 503R arranged around the mandrel 3 are connected to the main body 502.

When the pierced or elongated hollow shell 50 passes through the rear intercepting means 500, the plurality of rear intercepting fluid right injection holes 501R of the rear intercepting right member 500R are directed to the right portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32. The plurality of rear intercepting fluid right injection holes 501R are located around the mandrel bar 3 and arranged in the circumferential direction of the mandrel bar 3 as viewed in the traveling direction of the hollow shell 50. Preferably, the plurality of rear intercepting fluid right injection holes 501R are arranged at equal intervals around the mandrel 3. Further, the plurality of rear intercepting fluid right injection holes 501R may be arranged in parallel in the axial direction of the mandrel 3.

In piercing-rolling or elongating, when the hollow shell 50 is cooled in the cooling zone 32 by the outer surface cooling mechanism 400, the rear intercepting right member 500R sprays the rear intercepting fluid BF from the plurality of rear intercepting fluid right injection holes 501R toward the right portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32 and the intercepting cooling fluid CF flows toward the right portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

[ operation of the rear catching mechanism 500]

In the piercing-rolling or the elongating, the outer surface cooling mechanism 400 sprays the cooling fluid CF to the outer surface portion of the hollow shell 50 in the cooling zone 32 out of the outer surface of the hollow shell 50 subjected to the piercing-rolling or the elongating to cool the hollow shell 50. At this time, the following may occur: the cooling fluid CF injected to the outer surface portion of the hollow shell 50 in the cooling zone 32 contacts the outer surface portion of the hollow shell 50, and then flows rearward of the outer surface portion to contact the outer surface portion of the hollow shell 50 rearward of the cooling zone 32. As long as the occurrence frequency of such contact of the cooling fluid CF with the outer surface portion other than the cooling region 32 becomes high, the temperature distribution in the axial direction of the hollow shell 50 may be deviated.

Therefore, in the present embodiment, at the time of piercing-rolling or elongating, the rear intercepting means 500 suppresses the cooling fluid CF flowing on the outer surface from coming into contact with the outer surface portion of the hollow shell 50 in the cooling zone 32 after coming into contact with the outer surface portion of the hollow shell 50 in the rear of the cooling zone 32.

Specifically, when the outer surface cooling means 400 sprays the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32 to cool the hollow shell in the cooling zone 32, the rear intercepting upper member 500U sprays the rear intercepting fluid BF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, and forms a dam (a barrier wall) composed of the rear intercepting fluid BF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, as viewed in the traveling direction of the hollow shell 50, after the upper portion of the outer surface of the hollow shell 50 located in the cooling zone 32, a dam (a barrier wall) composed of the rear intercepting fluid BF is formed, as the rear intercepting fluid BF is sprayed toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, and forms a dam (a barrier wall) composed of the cooling fluid BF) in the vicinity of the outer surface of the left portion of the outer surface of the hollow shell 50 located in the cooling zone 32, and the right portion of the outer surface of the hollow shell 50 located in the cooling zone 32, and the rear portion of the cooling zone 32, the outer surface of the hollow shell 50, the cooling zone b is sprayed with the fluid CF fluid BF fluid CF 32, and forms a dam (a dam fluid BF) sprayed fluid BF) to inhibit the rear fluid BF portion located in the rear barrier wall) and forms a rear barrier wall) after the rear portion located in the rear barrier wall 32, and a rear portion located in the rear portion of the cooling zone b, and a rear barrier wall 32, and a rear portion of the cooling.

Fig. 40 is a sectional view of the back intercepting upper member 500U parallel to the traveling direction of the hollow shell 50, fig. 41 is a sectional view of the back intercepting lower member 500D parallel to the traveling direction of the hollow shell 50, fig. 42 is a sectional view of the back intercepting left member 500L parallel to the traveling direction of the hollow shell 50, and fig. 43 is a sectional view of the back intercepting right member 500R parallel to the traveling direction of the hollow shell 50.

Referring to fig. 40, it is preferable that the back intercepting upper member 500U sprays the back intercepting fluid BF. diagonally forward from the back intercepting fluid upper injection holes 501U toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, it is preferable that the back intercepting lower member 500D sprays the back intercepting fluid BF. diagonally forward from the back intercepting fluid lower injection holes 501D toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, it is preferable that the back intercepting left member 500L sprays the back intercepting fluid BF. diagonally forward from the back intercepting fluid left injection holes 501L toward the left portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, it is preferable that the back intercepting right member 500R sprays the back intercepting BF fluid diagonally forward from the back intercepting fluid right portion 501R toward the right portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32.

In fig. 40 to 43, the upper rearward intercepting member 500U forms a dam (a retaining wall) for intercepting the fluid BF rearward extending diagonally forward from above the hollow shell 50 toward an upper portion of the outer surface of the hollow shell 50. similarly, the lower rearward intercepting member 500D forms a dam (a retaining wall) for intercepting the fluid BF rearward extending diagonally forward from below the hollow shell 50 toward a lower portion of the outer surface of the hollow shell 50. similarly, the left rearward intercepting member 500L forms a dam (a retaining wall) for intercepting the fluid BF rearward extending diagonally forward from left of the hollow shell 50 toward left of the outer surface of the hollow shell 50. similarly, the right rearward intercepting member 500R forms a dam (a retaining wall) for intercepting the fluid BF rearward extending diagonally forward from right of the hollow shell 50 toward right of the outer surface of the hollow shell 50. these dams contact and splash back with the outer surface portion of the hollow shell 50 in the cooling region 32, and the dam (the retaining wall) forms a region for intercepting the fluid BF rearward contacting the outer surface of the cooling region 32, and the region 32 is in which the cooling fluid BF 30 easily splashes rearward intercepting region 32, and thus the cooling fluid BF is more easily cooled than the region 32.

Further, each of the rear intercepting members (the upper rear intercepting member 500U, the lower rear intercepting member 500D, the left rear intercepting member 500L, and the right rear intercepting member 500R) may eject the rear intercepting fluid BF. from each of the rear intercepting fluid ejection holes (the upper rear intercepting fluid ejection hole 501U, the lower rear intercepting fluid ejection hole 501D, the left rear intercepting fluid ejection hole 501L, and the right rear intercepting fluid ejection hole 501R) toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 located in the vicinity of the exit side of the cooling zone 32 without ejecting the rear intercepting fluid BF. diagonally forward, for example, the upper rear intercepting member 500U may eject the rear fluid BF. from the upper rear intercepting fluid ejection hole 501U along the radial direction of the mandrel 3, the lower rear intercepting member 500D may eject the rear intercepting fluid BF. from the lower rear intercepting fluid ejection hole 501D along the radial direction of the mandrel 3, or the left rear left member 500L may eject the rear intercepting fluid BF. from the left rear fluid ejection hole 501L along the radial direction of the mandrel 3, and the rear intercepting right rear intercepting fluid BF 3 from the rear fluid ejection hole 501R.

The back intercepting fluid BF is a gas and/or a liquid. That is, as the back-up flow BF, either a gas or a liquid may be used, or both a gas and a liquid may be used. Here, the gas is, for example, air or an inert gas. The inert gas is, for example, argon or nitrogen. In the case where a gas is used as the rear intercepting fluid BF, only air may be used, only an inert gas may be used, or both air and an inert gas may be used. As the inert gas, only 1 kind of inert gas (for example, only argon gas, only nitrogen gas) may be used, or a plurality of inert gases may be mixed and used. In case a liquid is used as the back-intercept fluid BF, the liquid is for example water, oil, preferably water.

The backward intercepting means 500 receives the supply of the backward intercepting fluid BF from a fluid supply source (not shown), and the fluid supply source has the same configuration as the fluid supply source 800, for example, the backward intercepting fluid BF supplied from the fluid supply source is ejected from the respective backward intercepting fluid ejection holes (the backward intercepting fluid upper ejection hole 501U, the backward intercepting fluid lower ejection hole 501D, the backward intercepting fluid left ejection hole 501L, and the backward intercepting fluid right ejection hole 501R) through a fluid path in the main body 502 of the backward intercepting means 500.

The configuration of the rear barrier mechanism 500 is not limited to fig. 38 to 43, for example, in fig. 39, the upper rear barrier member 500U, the lower rear barrier member 500D, the left rear barrier member 500L, and the right rear barrier member 500R are separate members independent of each other, however, as shown in fig. 44, the upper rear barrier member 500U, the lower rear barrier member 500D, the left rear barrier member 500L, and the right rear barrier member 500R may be integrally connected.

In addition, any one of the rear intercepting upper member 500U, the rear intercepting lower member 500D, the rear intercepting left member 500L, and the rear intercepting right member 500R may be configured of a plurality of members, or may be connected to a portion of the adjacent rear intercepting member, in FIG. 45, the rear intercepting left member 500L is configured of two members (500L U, 500L D), and the upper member 500L U of the rear intercepting left member 500L is connected to the rear intercepting upper member 500U, and the lower member 500L D of the rear intercepting left member 500L is connected to the rear intercepting lower member 500D, and in addition, the rear intercepting right member 500R is configured of two members (500RU, 500RD), and the upper member 500RU of the rear intercepting right member 500R is connected to the rear intercepting upper member 500U, and the lower member 500RD of the rear intercepting right member 500R is connected to the rear intercepting lower member 500D.

In short, each of the rear intercepting members (the upper rear intercepting member 500U, the lower rear intercepting member 500D, the left rear intercepting member 500L, the right rear intercepting member 500R) may be provided with a plurality of members, or may be partially or entirely formed integrally with the other rear intercepting members, and as long as the upper rear intercepting member 500U sprays the rear intercepting fluid BF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, the lower rear intercepting member 500D sprays the rear intercepting fluid BF toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, the left rear intercepting member 500L sprays the rear intercepting fluid BF toward the left portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, the right rear intercepting member 500R sprays the rear intercepting fluid BF toward the right portion of the outer surface of the hollow shell 50 located in the vicinity of the outlet side of the cooling zone 32, and the cooling fluid CF flows toward the outer surface of the hollow shell 50 after exiting from the cooling zone 32, the rear intercepting members (the upper rear intercepting members 500U, the lower rear intercepting members 500D, the lower rear intercepting member 500D, the left rear intercepting member 500R.

As shown in fig. 46, the rear intercepting means 500 may include a rear intercepting upper member 500U, a rear intercepting left member 500L, and a rear intercepting right member 500R, and may not include a rear intercepting lower member 500D. the cooling fluid CF jetted from the outer surface cooling means 400 toward the lower portion of the outer surface of the hollow shell 50 in the cooling zone 32 is likely to directly fall down toward the lower portion of the hollow shell 50 due to gravity after contacting the lower portion of the outer surface of the hollow shell 50. therefore, the cooling fluid CF jetted from the outer surface cooling means 400 toward the lower portion of the outer surface of the hollow shell 50 in the cooling zone 32 is less likely to flow toward the lower portion of the outer surface of the hollow shell behind the cooling zone 32 due to gravity, and therefore, the rear intercepting means 500 may not include the rear intercepting lower member 500D. as shown in fig. 47, the rear intercepting means 500 may include the rear intercepting upper member 500U, the rear intercepting left member 500L, and the rear intercepting right member 500R, and may not include the rear intercepting lower member 500D, and the left intercepting member 500 b may be disposed closer to the central axis of the mandrel bar 3 than the central axis of the mandrel bar 3, and the mandrel bar 3 is more likely to be disposed closer to the central axis of the hollow shell than the central axis of the mandrel bar 3.

The rear catching mechanism 500 may have a structure different from that of fig. 38 to 47. For example, as shown in fig. 48 and 49, the rear catching mechanism 500 may also use a mechanism of a plurality of catching members. In this case, as shown in fig. 48, the rear catching mechanism 500 includes a plurality of catching members 504 arranged around the mandrel 3. The plurality of catching members 504 are rollers as shown in fig. 48, for example. In the case where the intercepting member 504 is a roller, as shown in fig. 48 and 49, it is preferable that the roller surface of the intercepting member 504 is curved so that the roller surface of the intercepting member 504 is in contact with the outer surface of the hollow shell 50. The blocking member 504 is movable in the radial direction of the mandrel 3 by a movement mechanism not shown. The moving mechanism is, for example, a cylinder. The cylinder may be hydraulic, pneumatic, or electric.

During piercing and elongating, the plurality of catching members 504 are moved in the radial direction toward the outer surface of the hollow shell 50 as the hollow shell 50 passes through the rear catching mechanism 500. As shown in fig. 49, the inner surfaces of the plurality of catching members 504 are disposed near the outer surface of the hollow shell 50. Thus, when the outer surface cooling mechanism 400 sprays the cooling fluid CF toward the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 in the cooling zone 32, the plurality of dam members 504 form a weir (a protection wall). Therefore, the rear intercepting means 500 intercepts the flow of the cooling fluid to the upper portion of the outer surface, the lower portion of the outer surface, the left portion of the outer surface, and the right portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32.

In this manner, the back-up mechanism 500 may be a structure that does not use the back-up fluid BF. The rear intercepting means 500 is not particularly limited as long as it has a means for intercepting the flow of the cooling fluid to the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 after the exit from the cooling zone 32 when the outer surface cooling means 400 cools the hollow shell 50.

[ 7 th embodiment ]

Fig. 50 is a diagram showing the configuration of the vicinity of the exit side of the inclined roll 1 of the piercing mill 10 according to embodiment 7. Referring to fig. 50, the piercing machine 10 according to embodiment 7 is provided with a front catching mechanism 600 and a rear catching mechanism 500, in comparison with the piercing machine 10 according to embodiment 4. That is, the piercing machine 10 according to embodiment 7 has a combination of embodiment 5 and embodiment 6.

The front barrier mechanism 600 of the present embodiment has the same configuration as the front barrier mechanism 600 of embodiment 5. The rear barrier mechanism 500 of the present embodiment has the same configuration as the rear barrier mechanism 500 of embodiment 6.

In the piercing mill 10 of the present embodiment, the front intercepting means 600 and the rear intercepting means 500 suppress the cooling fluid CF flowing on the outer surface portion after coming into contact with the outer surface portion of the hollow shell 50 in the cooling zone 32 from coming into contact with the outer surface portions of the hollow shell 50 in front of and behind the cooling zone 32 at the time of piercing-rolling or elongating. Further, the inner surface cooling mechanism 340 cools the inner surface of the hollow shell 50 in the cooling zone 32 at the time of piercing rolling or elongating rolling.

Specifically, the front intercepting means 600 includes means for intercepting the cooling fluid, when the cooling zone 32 is cooled by spraying the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 in the outer surface cooling means 400, the cooling fluid is sprayed toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 before entering the cooling zone 32, and specifically, as viewed in the direction of travel of the hollow shell 50, the front intercepting upper member 600U sprays the front intercepting fluid FF toward the upper portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32 to form a dam (retaining wall) composed of the front intercepting fluid FF toward the upper portion of the outer surface of the hollow shell 50 before entering the cooling zone 32, and as the front intercepting fluid FF is sprayed toward the lower portion of the outer surface of the hollow shell 50 located in the vicinity of the entry side of the cooling zone 32, and as the front fluid FF is sprayed toward the outer surface of the cooling zone 32, and the front intercepting fluid FF is sprayed toward the outer surface of the cooling zone 32, and the cooling fluid FF is sprayed toward the front portion of the outer surface of the cooling zone 32, and the cooling zone 50, and the front intercepting fluid FF is formed by the front fluid FF of the cooling zone 32.

Specifically, when the outer surface cooling means 400 sprays the cooling fluid CF toward the upper portion, the lower portion, the left portion, and the right portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, the rear intercepting upper member 500U sprays the rear intercepting fluid BF toward the upper portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, and a dam (a retaining wall) composed of the rear intercepting fluid BF is formed on the upper portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, as viewed in the traveling direction of the hollow shell 50, the rear intercepting upper member 500U sprays the rear intercepting fluid BF toward the lower portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, and a dam (a retaining wall) composed of the rear intercepting fluid BF is formed on the lower portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, and the rear intercepting fluid BF fluid is sprayed toward the lower portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32, and the cooling fluid CF intercepting upper portion of the outer surface of the hollow shell 50 after exiting from the cooling zone 32 sprays the dam (the dam retaining wall) toward the right portion of the outer surface of the cooling zone 32, and the cooling zone can be formed by spraying the cooling fluid BF fluid CF fluid onto the rear intercepting fluid BF fluid onto the lower portion, and the cooling zone 32, and the left portion of the cooling zone 32, and the cooling zone 32, and the cooling zone after the cooling zone, the cooling zone outside the cooling zone, the cooling zone 32.

Further, at the time of piercing rolling or elongating rolling, the inner surface cooling means 340 cools the inner surface of the hollow shell 50 in the cooling zone 32, while the inner surface intercepting means 350 inhibits the coolant sprayed from the inner surface cooling means 340 from contacting the inner surface of the hollow shell 50 coming out of the cooling zone 32.

According to the above configuration, in the piercing machine 10 of the present embodiment, the inner surface of the hollow shell 50 in the cooling zone 32 is cooled by the inner surface cooling mechanism 340, and the outer surface of the hollow shell 50 in the cooling zone 32 is cooled by the outer surface cooling mechanism 400, and further, the contact of the coolant C L with the inner surface of the hollow shell 50 after exiting from the cooling zone 32 can be suppressed by the inner surface intercepting mechanism 350, and the contact of the coolant CF with the outer surface portions of the hollow shell 50 before and after the cooling zone 32 can be suppressed by the front intercepting mechanism 600 and the rear intercepting mechanism 500, and therefore, the temperature variation in the axial direction of the hollow shell 50 can be further reduced.

In the piercing machine 10 according to embodiment 7, the front catching mechanism 600 may have the structure shown in fig. 36 and 37, and the rear catching mechanism 500 may have the structure shown in fig. 48 and 49.

As described above, the piercing mills according to embodiments 1 to 7 described above suppress the temperature difference between the tip end portion and the rear end portion of the hollow shell after piercing-rolling or elongating, and easily obtain a structure uniform in the longitudinal direction. In the case where the piercing mill of the above-described embodiment performs piercing-rolling at about 1000 ℃, for example, the hollow shell immediately after piercing-rolling is cooled by the inner surface cooling means 340 for 10 seconds, whereby the temperature of the hollow shell can be reduced to about 800 ℃.

The embodiments of the present invention have been described above. However, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be implemented by appropriately changing the above-described embodiments without departing from the scope of the present invention.

In the above embodiment, the clearance between the mandrel bar 3 and the inner surface of the hollow shell 50 in the cooling zone 32 at the time of piercing rolling and at the time of elongating rolling is filled with the coolant by the inner surface cooling means 340 and the inner surface intercepting means 350. However, the above-described gap of the cooling region 32 may not necessarily be filled with the cooling liquid. The effect of the present embodiment is obtained to some extent even if the above-described gap of the cooling zone 32 is not filled with the coolant as long as the inner surface of the hollow shell 50 in the cooling zone 32 can be cooled by the coolant and the flow of the coolant to the rear of the cooling zone 32 is suppressed by the inner surface intercepting means 350.

[ example 1]

A steel pipe having an outer diameter of 430mm and a wall thickness of 30mm was heated to 1000 ℃. After heating, the steel tube was naturally cooled for 3 seconds. Then, the water density required for the outer surface side and the inner surface side of the steel pipe was determined by simulation in the following cases: the inner and outer surfaces of the steel pipe were water-cooled for 10 seconds using the plug 3, the outer surface cooling mechanism 400, and the rear interception mechanism 500 shown in fig. 38, and the wall thickness center temperature was 800 ℃.

The obtained result is shown in fig. 51. As shown in fig. 51, it can be seen that: the relationship between the water density on the outer surface side and the water density on the inner surface side of the steel pipe is obtained in advance from the steel type, the outer diameter, and the thickness of the steel pipe, and the water density is set based on the result, whereby desired cooling can be performed.

[ example 2 ]

A steel pipe having an outer diameter of 406mm, a wall thickness of 30mm and a length of 2m was prepared. A thermocouple is embedded in the center of the steel pipe in the longitudinal direction. The thermocouple was disposed at the center of the wall thickness. The steel tube was heated at 950 ℃ for two hours. The inner surface of the heated steel pipe is cooled using the mandrel bar 3 shown in fig. 4. At this time, the steel pipe was conveyed at a speed of 6 m/min. In this case, the time from the entrance of the position (measurement position) in the inner surface of the steel pipe, in which the thermocouple is embedded, into the cooling zone 32 to the passage thereof is 10 seconds. During the transportation of the steel pipe, cooling water was sprayed from the cooling zone 32 by the inner surface cooling means 340, and compressed air was sprayed from the contact suppression zone 33 by the inner surface intercepting means 350, and the heat transfer coefficient at the measurement position was measured.

The measurement results are shown in fig. 52. Referring to fig. 52, the period during which the heat transfer coefficient increases refers to a period during which the measurement position is cooled by the coolant. In the above, the cooling time of the measurement position by the coolant was set to 10 seconds, but in the measurement result, the measurement position was cooled for 12 seconds. That is, the cooling time can be set to substantially the set time. This means that the rear intercepting means 500 sufficiently suppresses the coolant from contacting the inner surface portion of the steel pipe rearward of the cooling region 32.

[ example 3 ]

A steel pipe 900 having an outer diameter of 406mm, a wall thickness of 30mm and a length of 2000mm as shown in FIG. 53 was prepared. Thermocouples are embedded at the center position in the axial direction (longitudinal direction) of steel pipe 900 and at the center Position (PT) of the wall thickness of 0 °, the center Position (PS) of the wall thickness of 90 ° and the center Position (PB) of the wall thickness of 180 ° clockwise from the top of steel pipe 900 in the cross section perpendicular to the axial direction of steel pipe 900.

As shown in fig. 54 and 55, a dummy plug 3A (fig. 54) and a dummy plug 3B (fig. 55) which are dummy plugs 3 are prepared. Referring to fig. 54, the dummy plug 3A has a plurality of annularly arranged coolant injection hole groups 345 in the cooling region 32 of the plug main body 31A, and a plurality of annularly arranged gas injection hole groups 355 in the contact suppression region 33. Each of the annularly arranged coolant injection hole groups 345 includes a plurality of coolant injection holes 341 arranged at a pitch of 30 ° in the circumferential direction. The ejection direction F34 of each coolant ejection hole 341 is the radial direction of the rod main body 31A. Each of the annularly arranged gas injection hole groups 355 includes a plurality of compressed gas injection holes 351 arranged at a pitch of 30 ° in the circumferential direction. The injection direction F35 of each compressed gas injection hole 351 is the radial direction of the rod main body 31A. Further, a disc-shaped heat insulator 300 simulating the plug 2 is attached to the tip of the dummy rod 3A. The diameter of the heat insulator 300 corresponds to the inner diameter of the steel pipe 900.

Referring to fig. 55, the dummy plug 3B has a plurality of annularly arranged coolant injection hole groups 345 in the cooling region 32 of the plug main body 31B, and a plurality of annularly arranged gas injection hole groups 355 in the contact suppression region 33. The annularly arranged coolant injection hole group 345 includes a plurality of coolant injection holes 341 arranged at a pitch of 30 ° in the circumferential direction. In the dummy core rod 3B, a coolant ejection hole 341 is provided to the tip of the nozzle. The ejection direction F34 of each coolant ejection hole 341 is an angle of 79 ° with respect to the axial direction of the rod main body 31B, and as shown in fig. 55, the ejection direction F34 is a counterclockwise direction when the dummy core rod 3B is viewed from the front toward the rear in the axial direction. The annularly arranged gas injection hole group 355 includes a plurality of compressed gas injection holes 351 arranged at a pitch of 30 ° in the circumferential direction. In the dummy core rod 3B, a compressed gas injection hole 351 is provided to the tip of the nozzle. The injection direction F35 of each compressed gas injection hole 351 is 79 ° with respect to the axial direction of the rod main body 31B, and as shown in fig. 55, the injection direction F35 is counterclockwise when the dummy rod 3B is viewed from the front toward the rear in the axial direction. Further, a disc-shaped heat insulator 300 simulating the plug 2 is attached to the tip of the dummy rod 3B. The diameter of the heat insulator 300 corresponds to the inner diameter of the steel pipe 900.

The steel pipe embedded with the thermocouple was heated to 950 ℃ by the heating furnace, the steel pipe 900 was extracted from the heating furnace, and the inner surface of the steel pipe 900 was water-cooled using the dummy mandrel 3A, at this time, as shown in fig. 56, the dummy mandrel 3A was fixed and the steel pipe 900 passed through the dummy mandrel 3A at a transport speed of 6mpm, at this time, as shown in fig. 56, the inside of the steel pipe 900 was sealed by the heat insulator 300 of the dummy plug 2, the temperature (c) at the PT position, the PS position, and the PB position during the time when the steel pipe 900 passed through the dummy mandrel 3A was measured by the thermocouple, the injection amount (flow rate) at the time of cooling of the coolant injection hole 341 in the cooling zone 32 was 600L/min, in the cooling zone 32 under cooling, the inner surface of the steel pipe 900 was filled with the coolant, and the rod main body 31A, the injection amount (flow rate) of the compressed gas injection hole in the contact suppression zone was 4000/min, the cooling time (time when the steel pipe 900 passed through the cooling zone 32) was 12 seconds, the water-cooling time was performed by the dummy mandrel 3A PS position, and the entire length of the steel pipe 900Average heat transfer coefficient (W/m) at the position and PB position²K) is added. The ratio of the maximum value of the average heat transfer coefficient to the minimum value of the average heat transfer coefficient among the obtained 3 average heat transfer coefficients was found.

In this case, the dummy mandrel 3B was fixed so that the steel pipe 900 passed through the dummy mandrel 3B at a transport speed of 6mpm in the same manner as the dummy mandrel 3A, at this time, the thermal insulation 300 of the plug 2 was simulated so that the interior of the steel pipe 900 was sealed, the PT position, the PS position, and the temperature at the PB position (deg.c) during the time when the steel pipe 900 passed through the dummy mandrel 3B were measured by the thermocouple, the injection amount (PB flow rate) at the time of cooling the coolant jet holes 341 in the cooling region 32 was 600L/min, the injection amount (PB flow rate) of the compressed gas jet holes 351 in the contact suppression region 33 was 8300L/min, the cooling time (the time when the steel pipe 900 passed through the cooling region 32) was 10 seconds, and after the water cooling position (PS/m) and the average heat transfer coefficient (W/m) at the full length of the steel pipe were calculated by the dummy mandrel 3B²K) is added. The ratio of the maximum value of the average heat transfer coefficient to the minimum value of the average heat transfer coefficient among the obtained 3 average heat transfer coefficients was found.

[ test results ]

Fig. 57 is a graph showing the relationship between the elapsed time (seconds) in the dummy mandrel 3A and the temperatures (° c) at the PT position, the PS position, and the PB position. Fig. 58 is a graph showing the relationship between the elapsed time (seconds) in the dummy mandrel 3B and the temperatures (° c) at the PT position, the PS position, and the PB position.

Referring to fig. 57 and 58, the temperature deviations at the PT position, the PS position, and the PB position during the cooling period of the dummy core rod 3B in which the swirling flow occurs are smaller than those of the dummy core rod 3A.

In addition, the maximum value of the average heat transfer coefficient at the PT position, the PS position and the PB position in the dummy core rod 3A was 6000W/m²K, minimum 1580W/m²K, average heat transferThe maximum/minimum value of the coefficient is 3.8. In contrast, the maximum value of the average heat transfer coefficient at the PT position, the PS position and the PB position in the pseudo core rod 3B generating the swirling flow was 4000W/m²K, minimum value of 2000W/m²And/k, the maximum/minimum value of the average heat transfer coefficient was 2.0. Therefore, the pseudo plug 3B generating the swirling flow can cool the inner surface of the steel pipe more uniformly in the circumferential direction than the pseudo plug 3A.

Description of the reference numerals

1. A tilt roller; 2. ejecting the head; 3. a core rod; 7. a coolant supply device; 8. a gas supply device; 10. a piercing machine; 20. raw materials; 31. a rod body; 32. a cooling zone; 33. a contact-inhibiting region; 50. a hollow pipe blank; 340. an inner surface cooling mechanism; 350. an inner surface interception mechanism; 400. an outer surface cooling mechanism; 500. a rear interception mechanism; 600. a front interception mechanism.