阅读说明：本技术 成型装置及金属管 (Molding device and metal pipe ) 是由 井手章博 石塚正之 上野纪条 野际公宏 于 2019-02-06 设计创作，主要内容包括：一种成型装置,其使金属管材料膨胀从成型出具有管部及凸缘部的金属管,该成型装置具备：第1模具及第2模具,该第1模具及第2模具彼此成对,并且具有用于成型出管部的管成型面及用于成型出凸缘部的凸缘成型面；驱动部,驱动第1模具及第2模具中的至少一个；及控制部,控制驱动部,在第1模具的凸缘成型面及第2模具的凸缘成型面中的至少一个凸缘成型面上形成有突出部,该突出部具有闭模时不与另一个凸缘成型面抵接的突出量,控制部控制驱动部以使突出部按压凸缘部从而在凸缘部的局部上形成厚度变薄的薄壁部。(A forming device for expanding a metal pipe material to form a metal pipe having a pipe portion and a flange portion, the forming device comprising: a 1 st die and a 2 nd die which are paired with each other and have a pipe molding surface for molding the pipe portion and a flange molding surface for molding the flange portion; a driving part for driving at least one of the 1 st die and the 2 nd die; and a control unit for controlling the driving unit, wherein a protrusion is formed on at least one of the flange molding surface of the 1 st die and the flange molding surface of the 2 nd die, the protrusion has a protrusion amount which does not contact with the other flange molding surface when the dies are closed, and the control unit controls the driving unit to press the protrusion against the flange to form a thin portion with a reduced thickness on a part of the flange.)

1. A forming device for forming a metal pipe having a pipe portion and a flange portion by expanding a metal pipe material, the forming device comprising:

a 1 st die and a 2 nd die which are paired with each other and have a pipe molding surface for molding the pipe portion and a flange molding surface for molding the flange portion,

a driving unit configured to drive at least one of the 1 st die and the 2 nd die; and

a control section for controlling the drive section,

a protrusion having a protrusion amount not contacting the other flange molding surface when the mold is closed is formed on at least one of the flange molding surface of the 1 st mold and the flange molding surface of the 2 nd mold,

the control portion controls the drive portion to press the protruding portion against the flange portion to form a thin portion with a reduced thickness on a part of the flange portion.

2. The molding apparatus according to claim 1,

the protruding portions are formed intermittently on the flange molding surface along a length direction of the flange molding surface.

3. The molding apparatus according to claim 1 or 2,

the 1 st mold and the 2 nd mold have contact portions that contact each other when the molds are closed,

the protruding portion is formed further inward in the width direction than the contact portion.

4. A metal pipe having a pipe portion and a flange portion, wherein,

the flange portion has a thin portion with a reduced thickness in a part thereof.

Technical Field

The invention relates to a molding device and a metal pipe.

Background

Conventionally, there has been known a molding apparatus for molding a metal pipe by expanding a metal pipe material and using a molding die. For example, the forming apparatus disclosed in patent document 1 can form a metal pipe having a pipe portion and a flange portion. In this molding apparatus, a metal pipe material that has been electrically heated is placed in a molding die, and the molding die is closed to mold a flange portion and the metal pipe material is expanded to mold the metal pipe.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-

Disclosure of Invention

Technical problem to be solved by the invention

The flanged metal pipe molded by the molding apparatus is welded to another member by the flange portion. At this time, the flange portion may be welded while being pressed against another member. In this case, since the pressure required for welding is increased, problems such as electrode abrasion may occur, and it is difficult to weld while applying pressure.

Accordingly, an object of the present invention is to provide a forming apparatus and a metal pipe that can easily perform welding when welding while pressing a flange portion against another member.

Means for solving the technical problem

One embodiment of the present invention relates to a forming apparatus for forming a metal pipe having a pipe portion and a flange portion by expanding a metal pipe material, the forming apparatus including: a 1 st die and a 2 nd die which are paired with each other and have a pipe molding surface for molding the pipe portion and a flange molding surface for molding the flange portion; a driving part for driving at least one of the 1 st die and the 2 nd die; and a control unit for controlling the driving unit, wherein a protrusion is formed on at least one of the flange molding surface of the 1 st die and the flange molding surface of the 2 nd die, the protrusion has a protrusion amount which does not contact with the other flange molding surface when the dies are closed, and the control unit controls the driving unit to press the protrusion against the flange to form a thin portion with a reduced thickness on a part of the flange.

In the molding apparatus according to one aspect of the present invention, a protrusion having a protrusion amount that does not abut against the other flange molding surface when the mold is closed is formed on at least one of the flange molding surface of the 1 st mold and the flange molding surface of the 2 nd mold. The control unit controls the drive unit so that the protruding portion presses the flange portion to form a thin portion having a reduced thickness in a part of the flange portion. According to this configuration, the thin portion pressed by the protruding portion of the flange molding surface is formed in the flange portion of the metal pipe. The thin portion is a portion of the flange portion that is locally reduced in thickness. Therefore, when the flange portion is welded to another member, the pressure required for welding can be reduced by welding the thin portion having a small thickness. This makes it possible to easily perform welding when welding while pressing the flange portion against another member.

In the molding device, the protrusion may be intermittently formed on the flange molding surface along a length direction of the flange molding surface. In this way, the thickness of the portion of the flange portion along the longitudinal direction to be welded is reduced, while the thickness of the other portions is not reduced, so that the pressure at the time of pressing the flange portion can be reduced.

In the molding apparatus, the 1 st mold and the 2 nd mold may have contact portions that contact each other when the molds are closed, and the protruding portion may be formed further inside in the width direction than the contact portions. The contact portion defines a tip end of the flange portion. Therefore, since the protruding portion is formed further inward in the width direction than the contact portion, the protruding portion can press the flange portion at a position closer to the center in the width direction. This facilitates welding when welding the flange portion.

The metal pipe according to the present invention is a metal pipe having a pipe portion and a flange portion, wherein the flange portion has a thin portion having a reduced thickness in a part thereof.

According to the metal pipe of the present invention, the same operation and effect as those of the molding apparatus can be obtained.

Effects of the invention

According to the present invention, it is possible to provide a forming apparatus and a metal pipe that can easily perform welding when welding while pressing a flange portion against another member.

Drawings

Fig. 1 is a schematic configuration diagram showing a molding apparatus according to an embodiment of the present invention.

Fig. 2 is an enlarged view of the periphery of the electrode, in which (a) is a view showing a state where the electrode holds a metal tube material, (b) is a view showing a state where a gas supply nozzle presses the electrode, and (c) is a front view of the electrode.

Fig. 3 is a sectional view of the molding die.

Fig. 4 is an enlarged sectional view of the molding die.

Fig. 5 is an enlarged cross-sectional view of the flange portion and the flange molding surface.

In fig. 6, (a) is a view of the flange molding surface as viewed from above, and (b) is a view of the metal pipe as viewed from above.

Fig. 7 is a diagram showing the shape of a projection of a molding device according to a modification.

Fig. 8 is a diagram showing the shape of a projection of a molding device according to a modification.

Detailed Description

Hereinafter, preferred embodiments of the molding apparatus according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted.

< Structure of molding apparatus >

Fig. 1 is a schematic configuration diagram of a molding apparatus according to the present embodiment. As shown in fig. 1, a molding apparatus 10 for molding a metal pipe includes: a molding die 13 composed of an upper die (1 st die) 12 and a lower die (2 nd die) 11; a drive mechanism (drive unit) 80 that moves at least one of the upper mold 12 and the lower mold 11; a tube holding mechanism 30 that holds the metal tube material 14 arranged between the upper mold 12 and the lower mold 11; a heating mechanism 50 that heats the metal tube material 14 held by the tube holding mechanism 30 by supplying electricity thereto; a gas supply unit 60 for supplying high-pressure gas (gas) into the heated metal tube material 14 held between the upper die 12 and the lower die 11; a pair of gas supply mechanisms 40, 40 for supplying gas from the gas supply unit 60 into the metal tube material 14 held by the tube holding mechanism 30; and a water circulation mechanism 72 for forcibly cooling the molding die 13 with water, and the molding apparatus 10 further includes a control unit 70 for controlling the driving of the driving mechanism 80, the driving of the tube holding mechanism 30, the driving of the heating mechanism 50, and the gas supply of the gas supply unit 60, respectively, by the control unit 70.

The lower mold 11, which is one of the molding dies 13, is fixed to the base 15. The lower mold 11 is made of a large steel block, and has a rectangular cavity (recess) 16 on its upper surface. A cooling water passage 19 is formed in the lower die 11, and a thermocouple 21 inserted from below is provided substantially at the center of the lower die 11. The thermocouple 21 is supported by a spring 22 so as to be movable up and down.

A space 11a is provided near the left and right ends (left and right ends in fig. 1) of the lower mold 11, and movable portions (i.e., electrodes 17 and 18 (lower electrodes) described below) of the tube holding mechanism 30 are disposed in the space 11a so as to be movable up and down. Further, the metal pipe material 14 is placed on the lower electrodes 17 and 18, and the lower electrodes 17 and 18 are in contact with the metal pipe material 14 disposed between the upper mold 12 and the lower mold 11. Thereby, the lower electrodes 17, 18 are electrically connected to the metal tube material 14.

Insulating materials 91 for preventing current flow are provided between the lower mold 11 and the lower electrode 17, below the lower electrode 17, between the lower mold 11 and the lower electrode 18, and below the lower electrode 18, respectively. Each of the insulating members 91 is fixed to a movable portion (i.e., an advancing/retreating rod 95) of an actuator (not shown) constituting the tube holding mechanism 30. The actuator is used to move the lower electrodes 17, 18 and the like up and down, and a fixing portion of the actuator is held on the base 15 side together with the lower mold 11.

The upper mold 12, which is the other mold of the molding dies 13, is fixed to a slider 81, which will be described later, constituting the driving mechanism 80. The upper mold 12 is formed of a large steel block, has a cooling water passage 25 formed therein, and has a rectangular cavity (recess) 24 on the lower surface thereof. The cavity 24 is provided at a position facing the cavity 16 of the lower mold 11.

Similarly to the lower mold 11, a space 12a is provided near the left and right ends (left and right ends in fig. 1) of the upper mold 12, and movable portions (i.e., electrodes 17 and 18 (upper electrodes) described below) of the tube holding mechanism 30 are disposed in the space 12a so as to be movable up and down. In a state where the metal tube material 14 is placed on the lower electrodes 17 and 18, the upper electrodes 17 and 18 move downward and contact the metal tube material 14 disposed between the upper mold 12 and the lower mold 11. Thereby, the upper electrodes 17, 18 are electrically connected to the metal tube material 14.

Insulating material 101 for preventing current flow is provided between upper mold 12 and upper electrode 17 and above upper electrode 17, and between upper mold 12 and upper electrode 18 and above upper electrode 18, respectively. Each insulating material 101 is fixed to a movable portion (i.e., the advancing-retreating rod 96) of the actuator constituting the tube holding mechanism 30. The actuator is used to move the upper electrodes 17, 18 and the like up and down, and a fixed portion of the actuator is held on the slider 81 side of the drive mechanism 80 together with the upper mold 12.

Semi-arc-shaped grooves 18a (see fig. 2) corresponding to the outer peripheral surface shape of the metal tube material 14 are formed in the surfaces of the electrodes 18, 18 facing each other in the right side portion of the tube holding mechanism 30, and the metal tube material 14 can be fitted into the groove 18a portion. As in the case of the above-described groove 18a, semi-arc-shaped grooves corresponding to the outer peripheral surface shape of the metal tube material 14 are formed on the exposed surfaces of the insulating materials 91 and 101 facing each other in the right side portion of the tube holding mechanism 30. A tapered concave surface 18b is formed on the front surface (surface facing the outside of the mold) of the electrode 18, the periphery of the groove 18a being recessed so as to be inclined in a conical shape toward the groove 18 a. Therefore, if the metal tube material 14 is sandwiched from the top-bottom direction by the right side portion of the tube holding mechanism 30, the entire outer periphery of the right side end portion of the metal tube material 14 can be surrounded tightly.

Semi-arc-shaped grooves 17a (see fig. 2) corresponding to the outer peripheral surface shape of the metal tube material 14 are formed in the surfaces of the electrodes 17, 17 facing each other at the left side portion of the tube holding mechanism 30, and the metal tube material 14 can be fitted into the groove 17a portion. As in the case of the above-described groove 17a, semi-arc-shaped grooves corresponding to the outer peripheral surface shape of the metal tube material 14 are formed on the exposed surfaces of the insulating materials 91 and 101 facing each other at the left side portion of the tube holding mechanism 30. A tapered concave surface 17b is formed on the front surface (surface facing the outside of the mold) of the electrode 17, the periphery of the groove 17a being recessed so as to be inclined in a conical shape toward the groove 17 a. Therefore, if the metal tube material 14 is sandwiched from above and below by the left side portion of the tube holding mechanism 30, the entire outer periphery of the left side end portion of the metal tube material 14 can be surrounded tightly.

As shown in fig. 1, the drive mechanism 80 includes: a slider 81 which moves the upper mold 12 in a direction in which the upper mold 12 and the lower mold 11 are closed to each other; a shaft 82 that generates a driving force for moving the slider 81; and a link 83 for transmitting the driving force generated by the shaft 82 to the slider 81. The shaft 82 extends in the left-right direction above the slider 81 and is rotatably supported. The eccentric crank 82a is coupled to a rotary shaft 81a provided on the upper portion of the slider 81 and extending in the left-right direction via a connecting rod 83. In the drive mechanism 80, the control unit 70 controls the rotation of the shaft 82 to change the height of the eccentric crank 82a in the vertical direction, and the change in the position of the eccentric crank 82a is transmitted to the slider 81 via the connecting rod 83, thereby controlling the vertical movement of the slider 81. Here, the swing (rotational motion) of the link 83 generated when the position change of the eccentric crank 82a is transmitted to the slider 81 is absorbed by the rotary shaft 81 a. The shaft 82 is rotated or stopped by driving of a motor or the like controlled by the control unit 70.

Fig. 3 is a sectional view of the molding die 13 shown in fig. 1. As shown in fig. 3, steps are provided on both the upper surface of lower mold 11 and the lower surface of upper mold 12.

On the upper surface of the lower mold 11, steps based on the 1 st projection 11b, the 2 nd projection 11c, the 3 rd projection 11d, and the 4 th projection 11e are formed, taking the bottom surface of the cavity 16 at the center of the lower mold 11 as a reference line LV 2. The 1 st projection 11b and the 2 nd projection 11c are formed on the right side of the cavity 16 (the right side in fig. 3, the back side of the paper in fig. 1), and the 3 rd projection 11d and the 4 th projection 11e are formed on the left side of the cavity 16 (the left side in fig. 3, the front side of the paper in fig. 1). The 2 nd protrusion 11c is located between the cavity 16 and the 1 st protrusion 11 b. The 3 rd protrusion 11d is located between the cavity 16 and the 4 th protrusion 11 e. The 2 nd projection 11c and the 3 rd projection 11d project further toward the upper mold 12 side than the 1 st projection 11b and the 4 th projection 11e, respectively. The 1 st projection 11b and the 4 th projection 11e project substantially equally from the reference line LV2, and the 2 nd projection 11c and the 3 rd projection 11d project substantially equally from the reference line LV 2.

On the other hand, on the lower surface of the upper mold 12, if the bottom surface of the cavity 24 at the center of the upper mold 12 is the reference line LV1, steps based on the 1 st projection 12b, the 2 nd projection 12c, the 3 rd projection 12d, and the 4 th projection 12e are formed. The 1 st projection 12b and the 2 nd projection 12c are formed on the right side (the right side in fig. 3) of the cavity 24, and the 3 rd projection 12d and the 4 th projection 12e are formed on the left side (the left side in fig. 3) of the cavity 24. The 2 nd protrusion 12c is located between the cavity 24 and the 1 st protrusion 12 b. The 3 rd projection 12d is located between the cavity 24 and the 4 th projection 12 e. The 1 st projection 12b and the 4 th projection 12e project further toward the lower pattern 11 side than the 2 nd projection 12c and the 3 rd projection 12d, respectively. The 1 st projection 12b and the 4 th projection 12e project substantially equally from the reference line LV1, and the 2 nd projection 12c and the 3 rd projection 12d project substantially equally from the reference line LV 1.

The 1 st projection 12b of the upper mold 12 faces the 1 st projection 11b of the lower mold 11, the 2 nd projection 12c of the upper mold 12 faces the 2 nd projection 11c of the lower mold 11, the cavity 24 of the upper mold 12 faces the cavity 16 of the lower mold 11, the 3 rd projection 12d of the upper mold 12 faces the 3 rd projection 11d of the lower mold 11, and the 4 th projection 12e of the upper mold 12 faces the 4 th projection 11e of the lower mold 11. Further, the amount of projection of the 1 st projection 12b with respect to the 2 nd projection 12c in the upper mold 12 (the amount of projection of the 4 th projection 12e with respect to the 3 rd projection 12 d) is larger than the amount of projection of the 2 nd projection 11c with respect to the 1 st projection 11b in the lower mold 11 (the amount of projection of the 3 rd projection 11d with respect to the 4 th projection 11 e). Therefore, in the case where the upper mold 12 and the lower mold 11 are fitted to each other, spaces are formed between the 2 nd protrusion 12c of the upper mold 12 and the 2 nd protrusion 11c of the lower mold 11, and between the 3 rd protrusion 12d of the upper mold 12 and the 3 rd protrusion 11d of the lower mold 11, respectively (refer to fig. 3 (c)). When the upper mold 12 and the lower mold 11 are fitted to each other, a space is formed between the cavity 24 of the upper mold 12 and the cavity 16 of the lower mold 11 (see fig. 3 (c)).

More specifically, at the time of blow molding, the lower mold 11 and the upper mold 12 are closed to each other, and at the time before fitting to each other, as shown in fig. 3 (b), a main cavity portion (1 st cavity portion) MC is formed between the bottom surface (surface serving as the reference line LV 1) of the cavity 24 of the upper mold 12 and the bottom surface (surface serving as the reference line LV 2) of the cavity 16 of the lower mold 11. A sub-cavity section (cavity section type 2) SC1, which communicates with the main cavity section MC and has a smaller volume than the main cavity section MC, is formed between the 2 nd projection 12c of the upper mold 12 and the 2 nd projection 11c of the lower mold 11. Similarly, a sub-cavity section (cavity section type 2) SC2, which communicates with the main cavity section MC and has a smaller volume than the main cavity section MC, is formed between the 3 rd projection 12d of the upper mold 12 and the 3 rd projection 11d of the lower mold 11. The main cavity portion MC is a portion where the pipe portion 100a of the metal pipe 100 is molded, and the sub cavity portion SC1 and the sub cavity portion SC2 are portions where the flange portion 100b and the flange portion 100c of the metal pipe 100 are molded, respectively (see fig. 3 (c) and (d)). As shown in fig. 3 (c) and (d), when the lower mold 11 and the upper mold 12 are continuously closed and completely clamped (fitted), the main cavity portion MC and the sub cavity portions SC1 and SC2 are sealed inside the lower mold 11 and the upper mold 12.

As shown in fig. 1, the heating mechanism 50 includes a power supply portion 55 and a bus bar 52 that electrically connects the power supply portion 55 and the electrodes 17 and 18. The power supply unit 55 includes a dc power supply and a switch, and the power supply unit 55 can supply power to the metal tube material 14 through the bus bar 52 and the electrodes 17 and 18 in a state where the electrodes 17 and 18 are electrically connected to the metal tube material 14. In addition, the bus bar 52 is connected to the lower electrodes 17 and 18.

In the heating mechanism 50, the dc current output from the power supply unit 55 is transmitted through the bus bar 52 and input to the electrode 17. Then, a direct current is input to the electrode 18 after passing through the metal tube material 14. Then, the dc current is transmitted through the bus bar 52 and input to the power supply unit 55.

The pair of gas supply mechanisms 40 each include: a cylinder unit 42; a piston rod 43 that moves forward and backward in accordance with the operation of the cylinder unit 42; and a seal member 44 connected to the end of the piston rod 43 on the tube holding mechanism 30 side. The cylinder unit 42 is mounted on and fixed to the block 41. A tapered surface 45 that tapers toward the tip is formed at the tip of the seal member 44, and the tapered surface 45 is configured in a shape that matches the tapered concave surfaces 17b, 18b of the electrodes 17, 18 (see fig. 2). The seal member 44 is provided with a gas passage 46 extending from the cylinder block 42 side toward the tip end, and specifically, as shown in fig. 2 (a) and (b), the gas passage 46 is through which high-pressure gas supplied from the gas supply portion 60 flows.

The gas supply unit 60 includes a gas source 61, a gas tank 62 for storing gas supplied from the gas source 61, a 1 st pipe 63 extending from the gas tank 62 to the cylinder unit 42 of the gas supply mechanism 40, a pressure control valve 64 and a switching valve 65 provided in the 1 st pipe 63, a 2 nd pipe 67 extending from the gas tank 62 to the gas passage 46 formed in the seal member 44, a pressure control valve 68 and a check valve 69 provided in the 2 nd pipe 67. The pressure control valve 64 functions as follows: the cylinder unit 42 is supplied with gas of a working pressure corresponding to the thrust of the sealing member 44 against the metal tube material 14. The check valve 69 functions as follows: preventing the high pressure gas from flowing backward in the 2 nd pipe 67. The pressure control valve 68 provided in the 2 nd pipe 67 functions as follows: the gas of the working pressure for expanding the metal tube material 14 is supplied to the gas passage 46 of the sealing member 44 by the control of the control portion 70.

The control section 70 can supply gas of a desired operating pressure into the metal tube material 14 by controlling the pressure control valve 68 of the gas supply section 60. The control unit 70 receives the information transmitted from (a) shown in fig. 1, acquires temperature information from the thermocouple 21, and controls the driving mechanism 80, the power supply unit 55, and the like.

The water circulation mechanism 72 includes: a water tank 73 for storing water, a water pump 74 for pumping up the water stored in the water tank 73 and pressurizing the water to be sent to the cooling water passage 19 of the lower mold 11 and the cooling water passage 25 of the upper mold 12, and a pipe 75. Although not shown here, the pipe 75 may be provided with a cooling tower for reducing the temperature of water or a filter for purifying water.

< method for Forming Metal tube Using Forming device >

Next, a method of forming a metal pipe using the forming apparatus 10 will be described. First, a cylindrical metal pipe material 14 of quenchable steel is prepared. For example, the metal tube material 14 is placed (thrown) on the electrodes 17 and 18 on the lower die 11 side by a robot arm or the like. Since the grooves 17a, 18a are formed on the electrodes 17, 18, the metal tube material 14 is positioned by the grooves 17a, 18 a.

Next, the control unit 70 controls the driving mechanism 80 and the tube holding mechanism 30 so that the tube holding mechanism 30 holds the metal tube material 14. Specifically, the upper mold 12 and the upper electrodes 17 and 18 held on the slider 81 side are moved toward the lower mold 11 side by the driving of the driving mechanism 80, and the upper electrodes 17 and 18 and the lower electrodes 17 and 18 are moved forward and backward by the actuators provided in the tube holding mechanism 30, so that the vicinity of both side ends of the metal tube material 14 is held from above and below by the tube holding mechanism 30. Since the grooves 17a and 18a formed in the electrodes 17 and 18 and the grooves formed in the insulating members 91 and 101 are present in this clamping, the metal tube material 14 is in close contact with the entire circumference in the vicinity of both side ends thereof.

In addition, at this time, as shown in fig. 2 (a), the electrode 18 side end portion of the metal tube material 14 protrudes further toward the sealing member 44 side than the boundary between the groove 18a and the tapered concave surface 18b of the electrode 18 in the extending direction of the metal tube material 14. Likewise, the electrode 17 side end portion of the metal tube material 14 protrudes more toward the sealing member 44 side than the boundary between the groove 17a and the tapered concave surface 17b of the electrode 17 in the extending direction of the metal tube material 14. The lower surfaces of the upper electrodes 17 and 18 and the upper surfaces of the lower electrodes 17 and 18 are in contact with each other. However, the electrodes 17 and 18 may be configured to abut against a part of the metal tube material 14 in the circumferential direction, instead of being configured to abut against the entire circumference of both end portions of the metal tube material 14.

Next, the control portion 70 heats the metal tube material 14 by controlling the heating mechanism 50. Specifically, the control unit 70 controls the power supply unit 55 of the heating mechanism 50 to supply power. In this way, the electric power transmitted to the lower electrodes 17 and 18 via the bus bars 52 is supplied to the upper electrodes 17 and 18 sandwiching the metal tube material 14 and the metal tube material 14, and the metal tube material 14 itself generates heat based on joule heat based on the resistance of the metal tube material 14 itself. That is, the metal tube material 14 is in an electrically heated state.

Next, the control section 70 controls the driving mechanism 80 to close the forming die 13 with respect to the heated metal tube material 14. Thereby, the cavity 16 of the lower mold 11 and the cavity 24 of the upper mold 12 are combined with each other, and the metal tube material 14 is arranged and sealed in the cavity portion between the lower mold 11 and the upper mold 12.

Then, the cylinder unit 42 of the gas supply mechanism 40 is operated to advance the sealing member 44, thereby sealing both ends of the metal tube material 14. At this time, as shown in fig. 2 (b), the sealing member 44 presses the electrode 18 side end portion of the metal tube material 14, and a portion protruding toward the sealing member 44 side than a boundary between the groove 18a and the tapered concave surface 18b of the electrode 18 is deformed in a funnel shape like the tapered concave surface 18 b. Similarly, the sealing member 44 presses the electrode 17 side end portion of the metal tube material 14, and a portion protruding toward the sealing member 44 side with respect to the boundary between the groove 17a and the tapered concave surface 17b of the electrode 17 is deformed in a funnel shape similar to the tapered concave surface 17 b. After the sealing is completed, high-pressure gas is blown into the metal tube material 14, so that the metal tube material 14 softened by heating is formed into the same shape as that of the cavity portion.

Since the metal tube material 14 is softened by being heated to a high temperature (around 950 ℃), the gas supplied into the metal tube material 14 is thermally expanded. Therefore, as the supply gas, for example, compressed air is supplied, and the metal tube material 14 at 950 ℃ can be easily expanded by the compressed air thermally expanded.

The outer peripheral surface of the metal tube material 14 expanded by blow molding is rapidly cooled by contact with the cavity 16 of the lower mold 11 and rapidly cooled by contact with the cavity 24 of the upper mold 12 (since the heat capacities of the upper mold 12 and the lower mold 11 are large and controlled to be low temperature, heat on the tube surface is immediately taken away by the mold side as long as the metal tube material 14 is in contact with the upper mold 12 or the lower mold 11), and quenching is performed. This cooling method is called mold contact cooling or mold cooling. Immediately after being rapidly cooled, austenite is transformed into martensite (hereinafter, a phenomenon in which austenite is transformed into martensite is referred to as martensite transformation). Since the cooling speed becomes slow at the latter stage of cooling, martensite is transformed into another structure (troostite, sorbite, etc.) by regenerative heating. Therefore, a separate tempering treatment is not required. In the present embodiment, instead of the mold cooling, for example, a cooling medium may be supplied into the cavity 24 to perform the cooling, or in addition to the mold cooling, for example, a cooling medium may be supplied into the cavity 24 to perform the cooling. For example, the metal tube material 14 may be cooled by being brought into contact with the dies (the upper die 12 and the lower die 11) up to the start temperature of the martensitic transformation, and then the dies may be opened and a cooling medium (cooling gas) may be blown into the metal tube material 14 to cause the martensitic transformation.

As described above, the metal pipe material 14 is cooled after being blow molded, and then opened to obtain a metal pipe having a main body portion of, for example, a substantially rectangular cylindrical shape.

Here, the molding apparatus 10 has a structure in which the thickness of the flange portions 100b and 100c is locally reduced. This structure will be described below with reference to fig. 4 to 6. Fig. 4 is an enlarged sectional view of the molding die 13. Fig. 5 is an enlarged sectional view of the flange portion 100b at the time of mold closing. Fig. 6 (a) is a view of the flange molding surface as viewed from above. Fig. 6 (b) is a view of the flange portion 100b as viewed from above. In fig. 4, the upper mold 12 and the lower mold 11 are in an open state, and therefore, strictly speaking, the main cavity portion MC, the sub cavity portion SC1, and the sub cavity portion SC2 are not formed, but for convenience of explanation, the portions corresponding to the shapes of the molds in which these cavity portions are formed are denoted by the symbols "MC", "SC 1", and "SC 2".

As shown in fig. 4, the lower mold 11 and the upper mold 12 have flange molding surfaces F1 and F3 for forming the flange portion 100 b. The flange molding surfaces F1 and F3 are surfaces that face each other and constitute a sub cavity portion SC 1. The lower mold 11 and the upper mold 12 have flange molding surfaces F2 and F4 for forming the flange portion 100 c. The flange molding surfaces F2 and F4 are surfaces that face each other and constitute a sub cavity portion SC 2. The lower mold 11 and the upper mold 12 have tube forming surfaces F5 and F6 for forming the tube portion 100 a. The tube forming surfaces F5 and F6 are surfaces that constitute the main cavity portion MC.

The projections 111A and 111B are formed on the flange molding surfaces F1 and F2 of the sub cavity portions SC1 and SC2 of the lower mold 11. The protrusions 111A and 111B protrude further toward the flange molding surfaces F3 and F4 than the flange molding surfaces F1 and F2. Here, the flange molding surface F1 of the sub cavity portion SC1 of the lower mold 11 corresponds to the upper surface of the 2 nd projection 11 c. The flange molding surface F2 of the sub cavity portion SC2 of the lower mold 11 corresponds to the upper surface of the 3 rd projection 11 d. The surfaces of the protrusions 111A, 111B also correspond to the flange molding surfaces F1, F2. The projections 110A and 110B are formed on the flange molding surfaces F3 and F4 of the sub cavity portions SC1 and SC2 of the upper mold 12. The protrusions 110A and 110B protrude toward the flange molding surfaces F1 and F2 than the flange molding surfaces F3 and F4. Here, the flange molding surface F3 of the sub cavity portion SC1 of the upper mold 12 corresponds to the lower surface of the 2 nd protrusion 12 c. The flange molding surface F4 of the sub cavity portion SC2 of the upper mold 12 corresponds to the upper surface of the 4 th projection 12 e. The surfaces of the protrusions 110A and 110B also correspond to the flange molding surfaces F3 and F4. The tube forming surface F5 corresponds to the bottom surface and the side surfaces on both sides of the cavity 16. The tube forming surface F6 corresponds to the bottom surface and the side surfaces on both sides of the cavity 24.

In the case of closing the mold, the upper surfaces of the 1 st protrusions 11b of the lower mold 11 and the lower surfaces of the 1 st protrusions 12b of the upper mold 12 contact each other. Therefore, the 1 st projection 11b and the 1 st projection 12b correspond to contact portions that contact each other when the mold is closed. The protruding portions 111A, 110A are formed further inward in the width direction (to the left of the paper surface in fig. 4) than the contact portions (i.e., the 1 st projections 11b, 12 b). In the case of closing the mold, the upper surface of the 4 th protrusion 11e of the lower mold 11 and the lower surface of the 4 th protrusion 12e of the upper mold 12 contact each other. Therefore, the 4 th projection 11e and the 4 th projection 12e correspond to contact portions that contact each other when the mold is closed. The protruding portions 111B, 110B are formed further inward in the width direction (on the right side of the paper surface in fig. 4) than the contact portions (i.e., the 4 th protrusions 11e, 12 e).

The upper surfaces of the protrusions 111A and 111B are formed of flat surfaces disposed at a higher position than the flange molding surfaces F1 and F2. However, the shape of the upper surface of the protruding portions 111A and 111B is not particularly limited, and may be a curved surface or the like. The lower surfaces of the protrusions 110A and 110B are flat surfaces disposed at positions lower than the flange molding surfaces F3 and F4. However, the shape of the lower surface of the protruding portions 110A and 110B is not particularly limited, and may be a curved surface or the like. The amount of projection of the projections 110A, 110B, 111A, and 111B is not particularly limited, but is set to an amount that does not come into contact with the other flange molding surface when the mold is closed (see fig. 5 (a)). The protrusions 110A and 110B are formed integrally with the upper mold 12, and the protrusions 111A and 111B are formed integrally with the lower mold 11. However, the projections 110A, 110B, 111A, and 111B may be formed as separate members from the mold. Further, only at least one of the projections 111A and 111B may be formed. Only at least one of the projections 110A and 110B may be formed.

Next, a state in which the protruding portion 111A is viewed from above will be described with reference to fig. 6 (a). The other protruding portions 111B, 110A, and 110B also have the same configuration as the protruding portion 111A. As shown in fig. 6 (a), the protruding portion 111A is formed on the flange molding surface F1 further inward than the outer end E1. The protrusion 111A is formed on the flange molding surface F1 further inward than the inner end E2. The protruding portions 111A are arranged in two rows so as to be spaced apart from each other in the width direction. The size of each projection 111A in the width direction is not particularly limited, but is preferably about 10 to 50% of the flange molding surface so as to press a part of the flange portion. The position of the protrusion 111A in the width direction of the flange molding surface F1 is not particularly limited.

The protrusions 111A are intermittently formed on the flange molding surface F1 in the longitudinal direction of the flange molding surface F1 (i.e., the extending direction of the metal pipe). Therefore, a gap is formed between the one projection 111A and the other projection 111A in the longitudinal direction. The size of the gap and the like are not particularly limited. In the embodiment shown in fig. 6 (a), the protruding portion 111A has a rectangular shape, but the shape is not particularly limited.

The metal pipe 100 having the flange portion 100b shown in fig. 5 (a) and 6 (b) is molded from the protruding portions 111A and 110A. The flange portion 100b has a thin portion 120 with a locally reduced thickness. The thickness of the thin portion 120 is thinner than the thickness of the portion of the flange portion 100b other than the thin portion 120. The thin portion 120 is formed at a position where a weld portion SP can be formed by spot welding when the metal pipe 100 is attached to another member. The thin portion 120 is formed in a portion of the flange portion 100b that is sandwiched and pressed by the protruding portions 111A and 110A from the top-bottom direction. That is, the thin portion 120 is formed between the recess formed by being pressed by the protruding portion 111A and the recess formed by being pressed by the protruding portion 110A.

The thin portions 120 are intermittently formed in the flange portion 100b along the longitudinal direction of the flange portion 100b (i.e., the extending direction of the metal pipe). The pitch in the longitudinal direction of the thin portion 120 is not particularly limited, and may be appropriately set according to the pitch of the welded portion SP. Further, if the thin portion 120 is formed at a pitch shorter than the pitch of the welded portion SP, the welding position can be selected at the time of welding. The thin portion 120 is formed at a position apart from both side ends in the width direction of the flange portion 100 b. The thin portions 120 are formed in two rows so as to be spaced apart from each other in the width direction of the flange portion 100 b. Thereby, the welded portion SP can be formed at two locations in the width direction during welding. Alternatively, the formation position of the weld portion SP can be selected in the width direction.

The thickness of the thin portion 120 is not particularly limited as long as it is within a range where the flange portion 100b is not penetrated. However, the thickness of the thin portion 120 may be set to about 30 to 70% of the thickness of the other portion of the flange portion 100b so as not to generate excessive pressure at the time of welding and not to generate excessive pressure at the time of molding. Also, since the flange portion 100b is formed by crushing the tube wall of the metal tube material, the flange portion 100b has a structure in which two tube walls are overlapped (refer to (a) in fig. 5). In this case, preferably, no gap is present between the two tube walls. However, in order to avoid excessive pressure, it is preferable not to excessively collapse the two-layer tube wall as in (b) of fig. 5. For example, when the thickness of the two-layer pipe wall before molding is 100%, the thickness of the flange portion 100b may be about 30 to 70%.

Controller 70 controls drive mechanism 80 so that projections 111A, 111B, 110A, and 110B press flange portions 100B and 100c to form thin portions 120 having a reduced thickness in portions of flange portions 100B and 100 c. In the present embodiment, when the mold is closed, the 1 st projection 11b contacts the 1 st projection 12b, and the 4 th projection 11e contacts the 4 th projection 12 e. Therefore, the control section 70 may close the molding die 13 until the contact portions contact each other. However, in the case of using the molding die 13 having no contact portion, the driving mechanism 80 is controlled so as not to apply an excessive pressure while adjusting the thicknesses of the flange portions 100b and 100c and the thin portion 120. The control unit 70 includes a processor, a memory, a storage, a communication interface, and a user interface, and is configured by a general computer or the like. The processor is an arithmetic Unit such as a Central Processing Unit (CPU). The Memory is a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The memory is a storage medium such as an HDD (Hard Disk Drive). The communication interface is a communication device that implements data communication. The processor centrally controls the memory, storage, communication interface and user interface to thereby implement the function of controlling the drive mechanism 80. In controlling the drive mechanism 80, for example, a program stored in the ROM is downloaded into the RAM, and the CPU is caused to execute the program downloaded into the RAM to thereby realize various functions. The control unit 70 may be constituted by one device, or may be constituted by combining different devices.

Next, the operation and effect of the molding apparatus 10 and the metal pipe 100 according to the present embodiment will be described.

For example, as a comparative example, there is an example in which the flange portions 100B and 100c are molded by a molding die not having the protruding portions 111A, 111B, 110A, and 110B as in the present embodiment. In this molding apparatus, the flange portions 100b and 100c are molded by pressing with a molding die, and at this time, the flange portions 100b and 100c have high hardness and a large thickness. When such a flange portion is welded to another member by pressing, a pressure required for welding increases, and there arise problems such as generation of dust, abrasion of an electrode, and unevenness in welding quality, which are caused by application of an excessive pressure. On the other hand, if the entire flange portions 100b and 100c are thinned as shown in fig. 5 (b) in order to reduce the thickness of the flange portions 100b and 100c, a very large pressure is required at the time of pressing.

In contrast, in the molding apparatus 10 according to the present embodiment, the protrusions 111A, 111B, 110A, and 110B are formed on the flange molding surfaces F1 and F2 of the lower mold 11 and the flange molding surfaces F3 and F4 of the upper mold 12, and the protrusions 111A, 111B, 110A, and 110B have a protrusion amount that does not come into contact with the other flange molding surface when the mold is closed. The controller 70 controls the driving mechanism 80 so that the protruding portions 111A, 111B, 110A, and 110B press the flange portions 100B and 100c to form thin portions 120 having a reduced thickness in parts of the flange portions 100B and 100 c. With this configuration, the flanges 100B and 100c of the metal pipe 100 are formed with the thin portions 120 pressed by the protruding portions 111A, 111B, 110A, and 110B of the flange molding surfaces F1, F2, F3, and F4. The thin portion 120 is a portion of the flange portions 100b and 100c that is locally reduced in thickness. Therefore, when the flange portions 100b and 100c are welded to other members, the pressure required for welding can be reduced by welding the thin portion 120 having a small thickness. Further, by forming the thin portion 120 locally, the pressure required for pressing can be reduced as compared with the case where the entire flange portions 100b and 100c are thinned (see fig. 5 (b)). This makes it possible to easily perform welding when welding while pressing the flanges 100b and 100c against other members.

In the molding apparatus 10, the protrusions 111A, 111B, 110A, 110B may be intermittently formed on the flange molding surfaces F1, F2, F3, F4 in the longitudinal direction of the flange molding surfaces F1, F2, F3, F4. Accordingly, the thickness of the welded portion of the portions of the flange portions 100b and 100c extending in the longitudinal direction is reduced, while the thickness of the other portions is not reduced, so that the pressing force of the flange portions 100b and 100c can be reduced.

In the molding apparatus 10, the lower mold 11 and the upper mold 12 may have contact portions that contact each other when the mold is closed, and the protruding portions 111A, 111B, 110A, and 110B may be formed further inward in the width direction than the contact portions. The contact portion defines the end of the flange portions 100b and 100 c. Therefore, since the protruding portions 111A, 111B, 110A, and 110B are formed further inward in the width direction than the contact portions, the protruding portions 111A, 111B, 110A, and 110B can press the widthwise center of the flange portions 100B and 100 c. This facilitates welding when welding the flanges 100b and 100 c.

The metal pipe 100 according to the present embodiment is a metal pipe 100 having a pipe portion 100a and flange portions 100b and 100c, and the flange portions 100b and 100c have a thin portion 120 having a reduced thickness in a part thereof.

According to the metal pipe 100 of the present embodiment, the same operation and effect as those of the molding apparatus 10 can be obtained.

The present invention is not limited to the above-described embodiments. For example, the overall structure of the molding apparatus is not limited to the structure shown in fig. 1, and can be appropriately modified within the scope not departing from the gist of the present invention.

The shape of the protruding portion (i.e., the shape of the thin portion) is not limited to the above embodiment, and various shapes can be adopted. For example, as shown in fig. 7 (a), the pair of projections 150 may extend continuously along the length direction of the flange molding surface. Also, as shown in fig. 7 (b), one protrusion 151 may continuously extend along the length direction of the flange molding surface. Also, as shown in fig. 7 (c), the protrusion 152 may have a circular shape arranged in two rows. As shown in fig. 7 (d), the protrusions 153 may have a circular shape arranged in a line. As shown in fig. 8 (a) and (b), the projections 154, 156 may have a rectangular shape arranged in a line. As shown in fig. 8 (c), the protrusion 157 may have a shape extending in the width direction. As shown in fig. 8 (d), the protrusion 158 may have a shape extending over the entire area in the width direction of the flange molding surface.

Description of the symbols

10-forming device, 11-down (1 st die), 12-up (2 nd die), 13-forming die, 14-metal tube material, 100-metal tube, 100A-tube portion, 100B, 100 c-flange portion, 110A, 110B, 111A, 111B-protrusion portion, 120-thin-walled portion.