阅读说明：本技术 钢管整体感应淬火专用装置及方法 (Special device and method for integral induction quenching of steel pipe ) 是由 杨煌光 袁进峰 张洋波 段松 李刚 李倩 于 2019-11-11 设计创作，主要内容包括：本发明提供一种钢管整体感应淬火专用装置及方法,所述专用装置包括连接接头,所述连接接头由左段、中段和右段依次连接而成,所述左段能够伸入一个所述钢管内,所述右段能够伸入另一个所述钢管内,所述中段能够位于两个首尾对接的所述钢管之间。该专用装置为一种可以循环使用的用于平端钢管(钢管的两端平头)的连接接头,使用在无缝钢管整体感应淬火生产过程中,能有效防止淬火过程冷却水流入钢管内孔；有效减轻感应加热端部效应；成功解决中碳CrMo薄壁无缝钢管(如42CrMo、4140、4145、4130等)整体感应淬火过程中的端部开裂、整体弯曲、性能不均匀等技术难题。(The invention provides a special device and a method for integral induction quenching of steel pipes, wherein the special device comprises a connecting joint, the connecting joint is formed by sequentially connecting a left section, a middle section and a right section, the left section can extend into one steel pipe, the right section can extend into the other steel pipe, and the middle section can be positioned between the two steel pipes which are butted end to end. The special device is a connecting joint which can be recycled and is used for a flat-end steel pipe (two flat ends of the steel pipe), and can effectively prevent cooling water from flowing into an inner hole of the steel pipe in the quenching process when the special device is used in the integral induction quenching production process of the seamless steel pipe; the induction heating end effect is effectively reduced; the technical problems of end cracking, integral bending, uneven performance and the like in the integral induction quenching process of the medium-carbon CrMo thin-wall seamless steel pipe (such as 42CrMo, 4140, 4145, 4130 and the like) are successfully solved.)

1. The utility model provides an overall induction hardening isolated plant of steel pipe, its characterized in that, isolated plant includes attach fitting, attach fitting is formed by left section, middle section and right section connect gradually, left side section can stretch into one in the steel pipe, right side section can stretch into another in the steel pipe, the middle section can be located two end to end between the steel pipe.

2. The special purpose device according to claim 1, wherein said left section, said middle section and said right section are all hollow cylindrical structures and are interconnected, the outer diameter of said middle section is larger than the outer diameters of said left section and said right section, and the outer diameter of said left section is equal to the outer diameter of said right section.

3. The special device according to claim 1, characterized in that the length M of the middle section is 20-30 mm, and the length L of the left and right sections is 50-60 mm.

4. The special device according to claim 1, characterized in that the outer diameter D1 of the left and right sections is 2-5 mm smaller than the inner diameter of the steel tube.

5. The special device according to claim 1, wherein the difference between the outer diameter D of the middle section and the outer diameter of the steel pipe is 1mm or less and-1 mm or more.

6. The special device according to claim 1, characterized in that the material of the connecting joint is 20 or 45 steel.

7. The special purpose device according to any one of claims 1-6, wherein the wall thickness S of the left and right sections is 8-10 mm.

8. The special device according to claim 7,

the left section and the right section both comprise a torus and a hollow frustum, one end of the torus of the left section and one end of the torus of the right section are respectively connected with the left end and the right end of the middle section, the other end of the torus of the left section and the other end of the torus of the right section are both connected with the big end of the hollow frustum,

preferably, the outer diameter of the torus is consistent with the outer diameter of the large end of the hollow frustum, the inner diameter of the torus is consistent with the inner diameter of the hollow frustum, the outer diameter of the small end of the hollow frustum is consistent with the inner diameter,

preferably, the included angle between the inner wall and the outer surface of the hollow frustum is 13-15 degrees.

9. The special device as claimed in claim 8, further comprising ceramic fiber cloth, wherein the ceramic fiber cloth is wound around the outer surface of the torus of the left and right sections, respectively, so that the outer diameter of the torus after being wound around the ceramic fiber cloth is equal to the inner diameter of the steel pipe.

10. A method for induction hardening of a steel pipe as a whole, characterized in that it uses a special apparatus as claimed in claims 1-9, said method comprising the steps of:

step 1, cutting two ends of the steel pipe into flat heads, and setting a roller way of an induction quenching production line to be sectionally controlled and variable-frequency;

step 2, winding ceramic fiber cloth at two end parts of the connecting joint, wherein the outer diameters of the two end parts of the connecting joint are consistent with the inner diameter of the steel pipe after winding;

step 3, one end part of each connecting joint is plugged into the inner wall of one end of the steel pipe to be quenched and tempered, a plurality of steel pipes with one ends plugged with the connecting joints sequentially pass through the roller way, one connecting joint is arranged between two adjacent steel pipes in the front and the back, before induction quenching, the speed of the roller way is controlled in a segmented mode, so that the speed of the steel pipe in the back is higher than that of the steel pipe in the front adjacent to the steel pipe in the front, the steel pipe in the back can automatically follow up and is connected with the steel pipe in the front adjacent to the steel pipe through the other end part of each connecting joint, and two adjacent steel pipes are tightly connected;

step 4, after the steel pipes are sequentially subjected to induction quenching and tempering, controlling the speed of the roller way to enable the speed of the steel pipe at the rear to be slower than that of the steel pipe at the front, and further enabling the steel pipe at the rear to be separated from the connecting joint;

step 5, cooling the plurality of tempered and separated steel pipes, and then disconnecting the adjacent front steel pipe from the connecting joint;

step 6, taking the connecting joint to a feeding area of the quenching process, and circulating the steps 3-5 to realize the recycling of the connecting joint;

preferably, the roller way is obliquely arranged, and the included angle between the roller way and the horizontal plane is 8-10 degrees;

preferably, the included angle between the cooling nozzle of the induction quenching production line and the advancing direction of the steel pipe is 35-40 degrees.

Technical Field

The invention relates to the field of heat treatment, in particular to a special device and a special method for integral induction quenching of a steel pipe.

Background

The induction heat treatment has the advantages of large energy flow density, high heating speed, high heat efficiency, little influence on environment and the like, is widely applied to the integral tempering heat treatment of various high-strength thin-wall steel pipes in the fields of oil drilling, geological drilling, coal mine excavation, capital construction detection and the like, and the product has the advantages of high strength, high toughness, fine grains, no decarburization, little oxidation and the like, and is greatly popularized and applied to small-batch tempering of thin-wall seamless steel pipes. But due to the inherent characteristics of induction heating, the technical problems of end cracking, integral bending, uneven performance and the like exist in the quenching and tempering process of the medium-carbon CrMo thin-wall seamless steel pipe.

In view of the above problems, three solutions are common at present. 1. And (4) flattening two ends of the steel pipe, and controlling the head and the tail of the adjacent steel pipes to be connected during quenching. The method is simple to operate, but the effects of the head end of the first steel pipe and the tail end of the last steel pipe are obvious, and the effect that the tail ends of the steel pipes are naturally connected end to end without dislocation and water does not enter the inner hole in the water quenching process can hardly be achieved in the rotating and advancing process of the steel pipes. 2. The ends of the steel pipe are plugged by electric welding after the two ends are cut flat, and then the steel pipe is produced according to the method 1. The method can thoroughly solve the problem of water inflow at the end part, but has low electric welding efficiency and increased cost, and is not suitable for mass production. 3. The end part is blocked by high temperature resistant materials such as asbestos or refractory mortar, and then the production is carried out according to the method 1. The method is simple, but the high-temperature resistant material is difficult to prevent high-pressure cooling water from entering the inner hole and can pollute the quenching medium. Therefore, the three methods can not well avoid the technical problems of end cracking, integral bending, uneven performance and the like of medium-carbon CrMo thin-wall seamless steel tubes (such as 42CrMo, 4140, 4145, 4130 and the like) in the integral induction water quenching process.

Therefore, a special device for integral induction quenching of the steel pipe is needed to solve the problems.

Disclosure of Invention

The invention aims to provide a special device and a special method for integral induction quenching of a steel pipe.

In order to achieve the above purpose, the invention provides the following technical scheme:

the utility model provides an overall induction hardening isolated plant of steel pipe, isolated plant includes attach fitting, attach fitting is formed by connecting gradually left section, middle section and right section, left side section can stretch into one in the steel pipe, right side section can stretch into another in the steel pipe, the middle section can be located two end to end between the steel pipe.

Further, in the above special device, the left section, the middle section and the right section are all hollow cylindrical structures and are communicated with each other, the outer diameter of the middle section is larger than the outer diameters of the left section and the right section, and the outer diameter of the left section is equal to the outer diameter of the right section.

Further, in the special device, the length M of the middle section is 20mm-30mm, and the lengths L of the left section and the right section are both 50mm-60 mm.

Further, in the special device, the outer diameter D1 of the left section and the right section is 2mm-5mm smaller than the inner diameter of the steel pipe.

Further, in the above-described special apparatus, a difference between the outer diameter D of the middle section and the outer diameter of the steel pipe is not more than 1mm and not less than-1 mm.

Further, in the above-mentioned exclusive use apparatus, the material of the connection joint is 20 # or 45 # steel.

Further, in the special device, the wall thickness S of the left section and the wall thickness S of the right section are both 8mm-10 mm.

Further, in the above special device, the left section and the right section both include a torus and a hollow frustum, one end of the torus of the left section and one end of the torus of the right section are respectively connected to the left end and the right end of the middle section, the other end of the torus of the left section and the other end of the torus of the right section are both connected to the large end of the hollow frustum,

preferably, the outer diameter of the torus is consistent with the outer diameter of the large end of the hollow frustum, the inner diameter of the torus is consistent with the inner diameter of the hollow frustum, the outer diameter of the small end of the hollow frustum is consistent with the inner diameter, and preferably, an included angle between the inner wall and the outer surface of the hollow frustum is 13-15 degrees.

Further, in the above special device, the special device further includes ceramic fiber cloth, and the ceramic fiber cloth is respectively wound on the outer surfaces of the torus of the left section and the right section, so that the outer diameter of the torus after being wound with the ceramic fiber cloth is equal to the inner diameter of the steel pipe.

On the other hand, the whole induction hardening method of the steel pipe is provided, and the method comprises the following steps of:

step 1, cutting two ends of the steel pipe into flat heads, and setting a roller way of an induction quenching production line to be sectionally controlled and variable-frequency;

step 2, winding ceramic fiber cloth at two end parts of the connecting joint, wherein the outer diameters of the two end parts of the connecting joint are consistent with the inner diameter of the steel pipe after winding;

step 3, one end part of each connecting joint is plugged into the inner wall of one end of the steel pipe to be quenched and tempered, a plurality of steel pipes with one ends plugged with the connecting joints sequentially pass through the roller way, one connecting joint is arranged between two adjacent steel pipes in the front and the back, before induction quenching, the speed of the roller way is controlled in a segmented mode, so that the speed of the steel pipe in the back is higher than that of the steel pipe in the front adjacent to the steel pipe in the front, the steel pipe in the back can automatically follow up and is connected with the steel pipe in the front adjacent to the steel pipe through the other end part of each connecting joint, and two adjacent steel pipes are tightly connected;

step 4, after the steel pipes are sequentially subjected to induction quenching and tempering, controlling the speed of the roller way to enable the speed of the steel pipe at the rear to be slower than that of the steel pipe at the front, and further enabling the steel pipe at the rear to be separated from the connecting joint;

step 5, cooling the plurality of tempered and separated steel pipes, and then disconnecting the adjacent front steel pipe from the connecting joint;

step 6, taking the connecting joint to a feeding area of the quenching process, and circulating the steps 3-5 to realize the recycling of the connecting joint;

preferably, the roller way is obliquely arranged, and the included angle between the roller way and the horizontal plane is 8-10 degrees;

preferably, the included angle between the cooling nozzle of the induction quenching production line and the advancing direction of the steel pipe is 35-40 degrees.

The analysis shows that the invention discloses a special device and a method for the integral induction quenching of a steel pipe, wherein the special device is a connecting joint which can be recycled and is used for a flat-end steel pipe (two flat ends of the steel pipe), and can effectively prevent cooling water from flowing into an inner hole of the steel pipe in the quenching process when the special device is used in the integral induction quenching production process of the seamless steel pipe; the induction heating end effect is effectively reduced; meanwhile, the effective automatic connection and separation of the head and the tail of the adjacent steel pipes are realized, and the special device is combined with special induction quenching heating and cooling control, so that the technical problems of end cracking, integral bending, uneven performance and the like of the medium-carbon CrMo thin-wall seamless steel pipes (such as 42CrMo, 4140, 4145, 4130 and the like) in the integral induction quenching process are successfully solved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. Wherein:

fig. 1 is a schematic structural diagram of an embodiment of the present invention.

Fig. 2 is a side view of fig. 1.

Fig. 3 is a schematic vertical cross-sectional view of the special device assembled with two steel pipes.

FIG. 4 is a schematic view of an included angle β between the axis of the cooling nozzle of the induction hardening line and the advancing direction of the steel pipe.

Description of reference numerals: 1, a middle section; 2, left section; 3, a right section; 4, ceramic fiber cloth; 5, steel pipes; 6, a nozzle;

m length of middle section; d, the outer diameter of the middle section; the outer diameter of the left section and the outer diameter of the right section of D1; s the wall thickness of the left section and the right section; the included angle between the inner wall and the outer surface of the alpha hollow frustum; c, the advancing direction of the steel pipe; and the included angle between the axis of the beta cooling nozzle and the advancing direction of the steel pipe.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. The various examples are provided by way of explanation of the invention, and not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.

In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are for convenience of description of the present invention only and do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. The terms "connected," "connected," and "disposed" as used herein are intended to be broadly construed, and may include, for example, fixed and removable connections; they may be directly connected or indirectly connected through intermediate members, and specific meanings of the above terms will be understood by those skilled in the art as appropriate.

As shown in fig. 1 to 3, according to an embodiment of the present invention, a special device for integral induction quenching of steel pipes is provided, which provides a transition joint for two adjacent steel pipes 5, and is capable of connecting the two adjacent steel pipes 5 before induction quenching heating, so as to solve the problems of end effect of the steel pipes 5 during induction quenching heating and water inflow of inner holes of the steel pipes 5 during cooling, and the special device includes a connection joint, which is formed by sequentially connecting a left section 2 (end a), a middle section 1 and a right section 3 (end B), wherein the left section 2 is capable of extending into one steel pipe 5, the right section 3 is capable of extending into another steel pipe 5, and the middle section 1 can be clamped between two adjacent steel pipes 5 that are butted end to end.

Further, left side section 2, middle section 1 and right side section 3 are hollow cylinder structure and communicate each other, and the external diameter of middle section 1 is greater than the external diameter of left side section 2 and right side section 3, and middle section 1 forms the step of outstanding left side section 2 and right side section 3, and the external diameter of left side section 2 equals with the external diameter of right side section 3, makes things convenient for the preparation and handles the steel pipe 5 of the same kind of specification. Preferably, the internal diameter of left side section 2, middle section 1 and right side section 3 equals, so set up and to make the hole of steel pipe 5 in the quenching and tempering process communicate in proper order, be favorable to the steel pipe in the transmission of heating and cooling process hole heat and air current, left side section 2, middle section 1 and right side section 3 adopt the hollow cylinder structure also be convenient for attach fitting's processing preparation simultaneously.

Further, the length M of the middle section 1 is 20mm-30mm (for example, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm), the length L of the left section 2 and the length L of the right section 3 are both 50mm-60mm (for example, 51mm, 52mm, 53mm, 54mm, 55mm, 56mm, 57mm, 58mm, 59mm) so as to facilitate the hand holding of the connection joint before the heat treatment to connect one end of the steel pipe 5 and take out the connection joint from one end of the steel pipe 5 after the heat treatment, the length L of the left section 2 and the length L of the right section 3 can be both convenient for winding the ceramic fiber cloth 4 at the two ends of the connection joint, the smooth connection between the connection joint and the inner hole of the steel pipe 5 is ensured, the strength of the connection joint and the reasonable weight of the connection joint can be ensured by comprehensively considering the above.

The closer the outer diameter D1 of the left section 2 and the right section 3 and the inner diameter of the steel pipe 5 are, the thinner the thickness of the ceramic fiber cloth 4 to be wound is, the smaller the influence of the end effect of the steel pipe 5 in the induction quenching process is, the better the heating temperature of the induction quenching and the uniformity of tempering and cooling are, the more stable the final performance is, the more the convenience of winding the ceramic fiber cloth 4 and the reuse of the connection joint are taken into consideration, and preferably, the outer diameter D1 of the left section 2 and the right section 3 is 2mm-5mm smaller than the inner diameter of the steel pipe 5.

Further, the difference between the outer diameter D of the middle section 1 and the outer diameter of the steel pipe 5 is controlled within the range of +/-1 mm, namely the outer diameter D of the middle section 1 is basically consistent with the outer diameter of the steel pipe 5. The arrangement can reduce the end effect generated by the steel pipe 5 in the integral induction quenching process and continuously produce roller way steel.

The upper limit value of the roughness Ra of the outer surface of the left section 2, the outer surface of the middle section 1, and the outer surface of the right section 3 may be 12.5 μm. The roughness has no hard requirement, and the normal machining level is only needed, or can not be controlled.

Further, in order to ensure the strength of the connecting joint and enable the connecting joint to be recycled, the material of the connecting joint is 20 # or 45 # steel.

Further, the wall thickness S of the left section 2 and the right section 3 is 8mm-10 mm. The wall thickness of the left section 2 and the right section 3 is too thin, so that the steel pipe is easy to deform during recycling, and the end effect of the steel pipe 5 is obviously enhanced if the wall thickness is too thick.

Further, left side section 2 and right side section 3 all include tourus and cavity frustum, and both ends about middle section 1 are connected respectively to two tourus one end, and the main aspects of a cavity frustum are all connected to the other end of two tourus. The outer diameter of the annular body is consistent with the outer diameter of the large end of the hollow frustum, the inner diameter of the annular body is consistent with the inner diameter of the hollow frustum, and the outer diameter of the small end of the hollow frustum is consistent with the inner diameter. The included angle alpha between the inner wall and the outer surface of the hollow frustum is 13-15 degrees, preferably 14 degrees, and the left section 2 and the right section 3 can be conveniently connected with the two steel pipes 5 respectively by the arrangement.

Furthermore, the special device also comprises a ceramic fiber cloth 4 which can resist the high temperature of 1000 ℃, and the ceramic fiber cloth 4 is respectively wound on the outer surfaces of the ring bodies of the left section 2 and the right section 3, so that the outer diameters of the ring bodies of the left section 2 and the right section 3 after the ceramic fiber cloth 4 is wound are equal to the inner diameter of the steel pipe 5. So set up and to make left side section 2 and right side section 3 respectively with two steel pipe 5 sealing connection, prevent at the induction hardening in-process, water gets into the hole of steel pipe 5, if do not have ceramic fibre cloth 4 to have a small amount of water to get into the steel pipe hole. One side of the ceramic fiber cloth 4 has viscosity, which is convenient for bonding with the connecting joint and bonding between the ceramic fiber cloth 4.

Specifically, the use method of the connecting joint comprises the following steps: evenly place many steel pipes 5 of treating the quenching and tempering on the material loading platform of roll table side, all twine ceramic fibre cloth 4 with attach fitting's both ends, the inner wall of treating the 5 one end of quenched and tempered steel pipe is filled in respectively with a plurality of attach fitting's of winding ceramic fibre cloth 4 one end, steel pipe 5 is dialled on segment control's roll table and is guaranteed to install an attach fitting between two adjacent steel pipes 5 around one by one through fixed stirring, before induction hardening, segment control roll table speed, make the speed that is located the steel pipe 5 at rear be faster than the steel pipe 5 in the place ahead, and then make the steel pipe 5 that is located the rear automatic with and entangle attach fitting's the other end, realize two adjacent steel pipe 5 zonulae occludens. As shown in fig. 3, the end portion a is inserted into the inner wall of one end of the steel pipe 5 manually, and the end portion is inserted horizontally and stably to prevent the connection joint from inclining, the inner wall of the steel pipe 5 is in close contact with the ceramic fiber cloth 4 wound on the end portion a of the connection joint, and the flat end of the steel pipe 5 is in close contact with the step (middle section 1) to prevent water from entering the inner hole of the steel pipe 5. In the normal steel running process, when feeding is started, the speed of a front-section roller way of an inlet-section roller way is lower than that of a rear-section roller way, a rear steel pipe 5 automatically follows up a connecting joint at the end part of a front adjacent steel pipe 5 and automatically sleeves the end part B of the connecting joint wound with the ceramic fiber cloth 4, the inner wall of the rear steel pipe 5 is in close contact with the ceramic fiber cloth 4 at the end part B of the connecting joint, and the close connection of the adjacent steel pipes is realized through the connecting joint; the releasing process is just opposite, namely the ceramic fiber cloth 4 is easily separated from steel after being heated and cooled at high temperature, so that when the speed of the roller way at the outlet section is higher than the normal process speed, one end of the connecting joint or the other end of the connecting joint is naturally separated from the steel pipe 5 connected with the connecting joint, and then two adjacent steel pipes 5 are released.

The invention also discloses a method for carrying out integral induction quenching on the steel pipe by using the special device comprising the connecting joint, which comprises the following steps:

step 1, in order to conveniently plug the connecting joint into the steel pipe 5, two ends of the steel pipe 5 to be quenched and tempered need to be flat-headed, and the two ends are provided with chamfers or the end part of the steel pipe 5 is smooth. The roller way of the induction quenching production line is set to be sectionally controlled and frequency-variable, the frequency of different roller way sections can be infinitely adjusted, and the steel pipe 5 can be automatically and tightly connected or disconnected with the connecting joint in the normal steel running process;

step 2, winding ceramic fiber cloth 4 at two end parts of the connecting joint, wherein the outer diameter of the ring body at the two end parts of the connecting joint is consistent with the inner diameter of the steel pipe 5 after winding, so that preparation is made for preventing water from entering the inner hole of the steel pipe 5 in the induction quenching process;

step 3, manually inserting one end part (such as the left section 2 of the connecting joint) of the connecting joint wound with the ceramic fiber cloth 4 into the inner wall of one end of a steel pipe 5 to be quenched and tempered, in the process, the end part of the connecting joint needs to be horizontally and stably inserted into the steel pipe 5 to prevent the connecting joint from inclining, the inner wall of the steel pipe 5 is tightly connected with the outer surface of one end of the connecting joint, one end of the steel pipe 5 is tightly connected with the middle section 1 of the connecting joint to prevent water from entering an inner hole, the steel pipes 5 are sequentially arranged through a roller way, a connecting joint is arranged between two adjacent steel pipes 5 in front and at back, before feeding for induction quenching, the speed of the roller way is controlled in a segmented mode to enable the speed of the steel pipe 5 at the back to be faster than that of the steel pipe 5 at the front, and further enable the steel pipe 5 at the back to automatically follow up and sleeve the other end (such, the automatic tight connection of the two adjacent steel pipes 5 is realized; the speed difference between the front roller way and the rear roller way is preferably that the steel pipe 5 positioned at the rear can be tightly connected with the connecting joint of the steel pipe 5 arranged at the front before entering the induction heating area, and is particularly related to the length of the roller way of the induction heating area and the speed of the roller way of the heating area required by the process and needs to be actually determined by combining with the site.

Step 4, after the steel pipes 5 are sequentially subjected to induction quenching and tempering, controlling the speed of the roller way to enable the speed of the steel pipe 5 positioned behind to be slower than that of the steel pipe 5 positioned in front, and further enabling the steel pipe 5 positioned behind to be automatically separated from the connecting joint; the difference in speed between the front and rear roller tables is preferably such that the two steel pipes 5 can be automatically released.

Step 5, disconnecting the connecting joint after the steel pipe 5 is cooled;

and 6, taking the connecting joint to a feeding area, and repeating the steps 3-5 to realize the recycling of the connecting joint. For the steel pipes 5 with the same specification, the connecting joint can be directly recycled, and for the steel pipes 5 with different specifications, the ceramic fiber cloth 4 with different thicknesses can be wound at the two ends (the left section 2 and the right section 3 of the connecting joint) of the connecting joint again for reuse. Preferably, the roller way is obliquely arranged, the included angle between the roller way and the horizontal plane is 8-10 degrees, and the arrangement can realize that the steel pipe 5 has certain rotation speed in the advancing process, so that the heating and cooling are ensured to be uniform.

Preferably, as shown in fig. 4, an angle β between an axis of the cooling nozzle 6 of the induction quenching production line and the advancing direction C of the steel pipe 5 is 35 ° to 40 ° (for example, 35 °, 36 °, 37 °, 38 °, 39 °, 40 °), and an angle β between a direction of cooling water sprayed from the cooling nozzle 6 and the advancing direction C of the steel pipe 5 is 35 ° to 40 °, so that the direct impact between the high-pressure water and the steel pipe 5 can be avoided while the inner hole is prevented from entering the inner hole of the steel pipe 5 by a large amount of hot air, and the angle β between the direction of cooling water sprayed from the cooling nozzle 6 and the advancing direction C of the steel pipe 5 is set to 35 ° to 40 ° as a further key measure for ensuring that the inner hole of the steel pipe 5 does not enter water.

In actual production, the connecting joint is combined with the ceramic fiber cloth 4 with viscidity on one surface (capable of resisting high temperature of 1000 ℃) and the sectional variable frequency control of a roller way, so that the problems of end effect generated in the process of induction quenching heating of the steel pipe 5 and water inflow of an inner hole of the steel pipe 5 in the quenching cooling process are successfully solved. In the process of induction quenching of the steel pipes 5, because one end of each of the first and last steel pipes 5 is not plugged, and water enters the inner holes of the two steel pipes 5, the induction quenching treatment is performed on the first steel pipe 5 again, and the tail part (the end without the joint) of the last steel pipe 5 is cut off to eliminate the end part affected area, wherein the cutting length is about 150 mm.