JP2020157354A - Metal pipe and method for molding metal pipe - Google Patents

Abstract

To provide a metal pipe having high rigidity while suppressing an increase in external dimension, and a molding method thereof.SOLUTION: According to an embodiment, a steel-made metal pipe as an integral molding is provided. The metal pipe has a cylindrical body part, and an inside flange projecting from the body part to the inside of the body part.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to metal pipes and methods for molding metal pipes.

Conventionally, there is known an apparatus for molding a metal pipe having a pipe portion and an outer flange portion extending outward from the pipe portion by expanding the metal pipe material in a molding die. For example, Patent Document 1 describes a molding die that forms a main cavity portion for molding a pipe portion and a pair of sub-cavity portions that communicate with the main cavity portion and form a pair of outer flange portions. The molding apparatus provided is disclosed. This molding device closes the molding die and blows gas into the heated metal pipe material to expand the metal pipe material in the main cavity portion and the pair of subcavities, and expands the metal pipe material in the pipe portion and the pair of outer flange portions. Mold a metal pipe with.

International Publication No. 2017/150110

In the apparatus described in Patent Document 1, the rigidity of the metal pipe is increased by forming a pair of outer flange portions on the metal pipe. However, the metal pipe with the outer flange has a larger external dimension by the amount of the outer flange portion in the width direction of the metal pipe than the metal pipe having no outer flange portion, so that the metal pipe interferes with other members. Therefore, it may not be possible to arrange the metal pipe in a predetermined space.

Therefore, an object of the present invention is to provide a metal pipe having high rigidity and a molding method thereof while suppressing an increase in external dimensions.

In one aspect, an integrally molded steel metal pipe is provided. The metal pipe includes a tubular main body portion and an inner flange protruding from the main body portion to the inside of the main body portion.

In this aspect, the rigidity of the metal pipe can be increased by the inner flange portion. Since this inner flange portion projects inward of the main body portion, it is possible to prevent an increase in the external dimensions of the metal pipe.

In one embodiment, the flange portion may be made of an inwardly folded steel material. By forming the inner flange portion from the steel material folded inward, the main body portion and the inner flange portion can be integrally formed, and as a result, the rigidity of the metal pipe can be increased.

In one embodiment, another inner flange portion that protrudes from the main body portion to the inside of the main body portion is further provided, and even if the inner flange portion and another inner flange portion protrude from the main body portion in a direction approaching each other. Good. The rigidity of the metal pipe can be further increased by providing the inner flange portion and another inner flange portion that project in the direction of approaching each other.

In one embodiment, an outer flange portion that protrudes from the main body portion to the outside of the main body portion may be further provided. By providing such an outer flange portion, the rigidity of the metal pipe can be further increased.

In one aspect, a forming method is provided in which a forming apparatus is used to form a steel metal pipe having a tubular main body and an inner flange protruding inward from the main body. This molding device has an upper mold and a lower mold, and has a molding mold for forming a main cavity portion for molding a metal pipe material between the upper mold and the lower mold, and an upper mold and a lower mold in the main cavity portion. A double-acting mold that can move forward and backward along the opposite direction of the mold, a heating mechanism that heats the metal pipe material arranged in the main cavity, and a gas supply unit that supplies gas into the heated metal pipe material. , Is equipped. The upper mold is a pair of upper sliding portions arranged apart from each other via the upper mold base portion and the main cavity portion, and is slidable with respect to the upper mold base portion so that the distance between them changes. The lower mold includes the pair of upper sliding portions, and the lower mold is a pair of lower sliding portions arranged apart from each other via the lower mold base portion and the main cavity portion, and the separation distance from each other changes. It includes the pair of lower sliding portions that are slidable with respect to the lower mold base. The molding method is a step of inserting a double-acting die into the main cavity portion and crushing the first portion of the metal pipe material arranged in the main cavity portion from the opposite direction, and separating the pair of upper sliding portions. A step of sliding the pair of upper sliding portions and the pair of lower sliding portions with respect to the upper mold base and the lower mold base, respectively, so as to reduce the distance and the separation distance of the pair of lower sliding portions. Then, while supplying gas from the gas supply part into the heated metal pipe material, the double acting mold is retracted from the main cavity part to form the first part of the metal pipe into the inner flange part. It includes a step of forming a second portion of the metal pipe into a main body portion.

In the method according to the above aspect, a metal pipe provided with a main body portion and an inner flange portion can be formed. Therefore, it is possible to increase the rigidity of the metal pipe while preventing the increase in the external dimensions of the metal pipe.

In the molding method according to one embodiment, the molding die communicates with the main cavity portion between the pair of upper sliding portions and the pair of lower sliding portions, and protrudes from the main body portion to the outside of the main body portion. A third portion of the metal pipe material is expanded in the subcavity by further forming a subcavity portion for forming the outer flange portion to be formed and supplying gas from the gas supply portion into the heated metal pipe material. It may be formed on the outer flange portion. In this embodiment, since the metal pipe further provided with the outer flange portion can be formed, the rigidity of the metal pipe can be further increased.

According to one aspect of the present invention and various embodiments, it is possible to provide a metal pipe having high rigidity while suppressing an increase in external dimensions.

It is a schematic block diagram which shows the molding apparatus which concerns on one Embodiment. An enlarged view of the periphery of the electrode, (a) is a view showing a state in which the electrode holds a metal pipe material, (b) is a view showing a state in which a gas supply nozzle is pressed against the electrode, and (c) is a front view of the electrode. It is a figure. It is sectional drawing of a molding die. It is a figure explaining the molding method of the metal pipe which concerns on 1st Embodiment. It is sectional drawing which shows the metal pipe which concerns on one Embodiment. It is a figure explaining the molding method of the metal pipe which concerns on 2nd Embodiment. It is sectional drawing which shows the metal pipe which concerns on Examples 1 to 3 and Comparative Examples 1 and 2. It is a figure which shows the moment of inertia of area and the section modulus of the metal pipe which concerns on Examples 1 to 3 and Comparative Examples 1 and 2.

Hereinafter, the molding apparatus used in the method for molding a metal pipe of one embodiment will be described with reference to the drawings. In each figure, the same parts or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. Hereinafter, one direction in the horizontal direction will be the X-axis direction, the direction orthogonal to the X-axis direction in the horizontal direction will be the Y-axis direction, and the vertical direction will be described as the Z-axis direction.

<Structure of molding equipment>
FIG. 1 is a schematic configuration diagram of a molding apparatus according to the present embodiment. As shown in FIG. 1, the molding apparatus 10 for molding a metal pipe includes a molding mold 13 composed of an upper mold 12 and a lower mold 11 and a drive mechanism 80 for moving at least one of the upper mold 12 and the lower mold 11. , A pipe holding mechanism 30 for holding the metal pipe material 14 arranged between the upper mold 12 and the lower mold 11, and a heating mechanism 50 for energizing and heating the metal pipe material 14 held by the pipe holding mechanism 30. A gas supply unit 60 for supplying high-pressure gas (gas) into the heated metal pipe material 14 held between the upper mold 12 and the lower mold 11, and a metal pipe material held by the pipe holding mechanism 30. A pair of gas supply mechanisms 40 and 40 for supplying gas from the gas supply unit 60 and a water circulation mechanism 72 for forcibly cooling the molding mold 13 with water are provided in 14, and the drive mechanism 80 is driven. It is configured to include a drive of the pipe holding mechanism 30, a drive of the heating mechanism 50, and a control unit 70 for controlling the gas supply of the gas supply unit 60, respectively.

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

Further, a space 11a is provided near the left and right ends (left and right ends in FIG. 1) of the lower mold 11, and the electrodes 17 and 18 (lower) described later, which are movable parts of the pipe holding mechanism 30, are provided in the space 11a. Side electrodes) and the like are arranged so that they can move up and down. Then, by placing the metal pipe material 14 on the lower electrodes 17 and 18, the lower electrodes 17 and 18 come into contact with the metal pipe material 14 arranged between the upper mold 12 and the lower mold 11. To do. As a result, the lower electrodes 17 and 18 are electrically connected to the metal pipe material 14.

An insulating material 91 for preventing energization is provided between the lower mold 11 and the lower electrode 17 and the lower portion of the lower electrode 17, and between the lower mold 11 and the lower electrode 18 and the lower portion of the lower electrode 18. Each is provided. Each of the insulating materials 91 is fixed to an advancing / retreating rod 95 which is a movable part of an actuator (not shown) constituting the pipe holding mechanism 30. This actuator is for moving the lower electrodes 17, 18 and the like up and down, and the fixed 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 side of the molding mold 13, is fixed to a slide 81, which will be described later, which constitutes the drive mechanism 80. The upper mold 12 is composed of a large steel block, has a cooling water passage 25 formed therein, and has, for example, 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.

Similar to the lower mold 11, a space 12a is provided in the vicinity of the left and right ends (left and right ends in FIG. 1) of the upper mold 12, and the space 12a is a movable part of the pipe holding mechanism 30 to be described later. Electrodes 17, 18 (upper electrodes) and the like are arranged so as to be able to move up and down. Then, in the state where the metal pipe material 14 is placed on the lower electrodes 17 and 18, the upper electrodes 17 and 18 are arranged between the upper mold 12 and the lower mold 11 by moving downward. Contact the metal pipe material 14. As a result, the upper electrodes 17 and 18 are electrically connected to the metal pipe material 14.

Insulating material 101 for preventing energization is provided between the upper mold 12 and the upper electrode 17 and the upper part of the upper electrode 17, and between the upper mold 12 and the upper electrode 18 and the upper part of the upper electrode 18, respectively. There is. Each insulating material 101 is fixed to an advancing / retreating rod 96 which is a movable part of an actuator constituting the pipe holding mechanism 30. This actuator is for moving the upper electrodes 17, 18 and the like up and down, and the fixed portion of the actuator is held on the slide 81 side of the drive mechanism 80 together with the upper mold 12.

In the right side portion of the pipe holding mechanism 30, a semicircular concave groove 18a corresponding to the outer peripheral surface of the metal pipe material 14 is formed on each of the surfaces of the electrodes 18 and 18 facing each other (FIG. 2 (c). ), The metal pipe material 14 can be placed so as to fit into the recessed groove 18a. In the right side portion of the pipe holding mechanism 30, a semicircular concave groove corresponding to the outer peripheral surface of the metal pipe material 14 is formed on the exposed surface where the insulating materials 91 and 101 face each other, similarly to the concave groove 18a. ing. Further, on the front surface of the electrode 18 (the surface in the outer direction of the mold), a tapered concave surface 18b is formed in which the periphery is inclined in a tapered shape toward the concave groove 18a. Therefore, when the metal pipe material 14 is sandwiched by the right side portion of the pipe holding mechanism 30 from the vertical direction, the outer circumference of the right end portion of the metal pipe material 14 can be surrounded so as to be in close contact with the entire circumference. ing.

In the left side portion of the pipe holding mechanism 30, a semicircular concave groove 17a corresponding to the outer peripheral surface of the metal pipe material 14 is formed on each of the surfaces of the electrodes 17 and 17 facing each other (FIG. 2 (c). ), The metal pipe material 14 can be placed so as to fit into the recessed groove 17a. In the left side portion of the pipe holding mechanism 30, a semicircular concave groove corresponding to the outer peripheral surface of the metal pipe material 14 is formed on the exposed surface where the insulating materials 91 and 101 face each other, similarly to the concave groove 18a. ing. Further, on the front surface of the electrode 17 (the surface in the outer direction of the mold), a tapered concave surface 17b is formed in which the periphery is inclined in a tapered shape toward the concave groove 17a. Therefore, when the metal pipe material 14 is sandwiched by the left side portion of the pipe holding mechanism 30 from the vertical direction, the outer circumference of the left end portion of the metal pipe material 14 can be surrounded so as to be in close contact with the entire circumference. ing.

As shown in FIG. 1, the drive mechanism 80 includes a slide 81 for moving the upper die 12 so that the upper die 12 and the lower die 11 are aligned with each other, and a shaft 82 for generating a driving force for moving the slide 81. And a connecting rod 83 for transmitting the driving force generated by the shaft 82 to the slide 81. The shaft 82 extends in the left-right direction above the slide 81 and is rotatably supported, and an eccentric crank 82a protruding from the left-right end and extending in the left-right direction at a position separated from the axis thereof. Have. The eccentric crank 82a and the rotating shaft 81a provided on the upper part of the slide 81 and extending in the left-right direction are connected by a connecting rod 83. In the drive mechanism 80, the rotation of the shaft 82 is controlled by the control unit 70 to change the height of the eccentric crank 82a in the vertical direction, and the position change of the eccentric crank 82a is transmitted to the slide 81 via the connecting rod 83. As a result, the vertical movement of the slide 81 can be controlled. Here, the swing (rotational motion) of the connecting rod 83 that occurs when the position change of the eccentric crank 82a is transmitted to the slide 81 is absorbed by the rotating shaft 81a. The shaft 82 rotates or stops according to the drive of a motor or the like controlled by, for example, the control unit 70.

FIG. 3 is a cross-sectional view of the molding die 13 shown in FIG. As shown in FIG. 3A, the lower mold 11 has a lower mold base 110, a first lower sliding portion 112a, and a second lower sliding portion 112b. Further, the upper mold 12 has an upper mold base 120, a first upper sliding portion 122a, and a second upper sliding portion 122b. Hereinafter, when it is not necessary to distinguish between them, the first lower sliding portion 112a and the second lower sliding portion 112b are referred to as a pair of lower sliding portions 112, and the first upper sliding portion 112b is referred to as a pair of lower sliding portions 112. The 122a and the second upper sliding portion 122b shall be referred to as a pair of upper sliding portions 122.

On the upper surface of the lower mold 11, a step is formed by a pair of lower sliding portions 112, assuming that the bottom surface of the cavity 16 in the center of the lower mold 11 is the reference line LV1. A first lower sliding portion 112a is formed on the right side of the cavity 16 (right side in FIG. 3 and the back side of the paper surface in FIG. 1), and on the left side of the cavity 16 (left side in FIG. 3 and front side of the paper surface in FIG. 1). The second lower sliding portion 112b is formed. The first lower sliding portion 112a and the second lower sliding portion 112b have a substantially rectangular cross-sectional shape and extend parallel to each other along the X-axis direction (paper direction in FIG. 3). are doing. The first lower sliding portion 112a and the second lower sliding portion 112b project from the reference line LV1 toward the upper mold 12 side. The amount of protrusion of the first lower sliding portion 112a from the reference line LV1 is substantially the same as the amount of protrusion of the second lower sliding portion 112b from the reference line LV1.

On the other hand, on the lower surface of the upper die 12, if the bottom surface of the cavity 24 in the center of the upper die 12 is the reference line LV2, a step is formed by the pair of upper sliding portions 122. A first upper sliding portion 122a is formed on the right side of the cavity 24 (right side in FIG. 3 and the back side of the paper surface in FIG. 1), and on the left side of the cavity 24 (left side in FIG. 3 and front side of the paper surface in FIG. 1). The second upper sliding portion 122b is formed. The first upper sliding portion 122a and the second upper sliding portion 122b have a substantially rectangular cross-sectional shape and extend in parallel with each other along the X-axis direction (paper direction in FIG. 3). There is. The first upper sliding portion 122a and the second upper sliding portion 122b project from the reference line LV2 toward the lower mold 11. The amount of protrusion of the first upper sliding portion 122a from the reference line LV2 is substantially the same as the amount of protrusion of the second upper sliding portion 122b from the reference line LV2.

Further, the first lower sliding portion 112a faces the first upper sliding portion 122a, and the second lower sliding portion 112b faces the second upper sliding portion 122b. As a result, when the upper mold 12 and the lower mold 11 are fitted, the upper surface 112a1 of the first lower sliding portion 112a and the lower surface 122a1 of the first upper sliding portion 122a come into contact with each other, and the second The upper surface 112b1 of the lower sliding portion 112b and the lower surface 122b1 of the second upper sliding portion 122b come into contact with each other. At this time, the main cavity portion MC is formed between the cavity 24 of the upper mold 12 and the cavity 16 of the lower mold 11 (see FIG. 3B). When the upper die 12 and the lower die 11 are fitted together, the main cavity portion MC has a pair of the cavity 24 of the upper die 12, the cavity 16 of the lower die 11, and a pair of lower sliding portions 112 facing each other. It is a space defined by the side surfaces 112a2 and 112b2 and the pair of side surfaces 122a2 and 122b2 facing each other of the pair of upper sliding portions 122.

Further, on the upper surface of the lower mold base 110, a pair of lower drive mechanisms 113 for driving the pair of lower sliding portions 112 are provided. Each of the pair of lower drive mechanisms 113 has a frame body 114. The frame body 114 has a U-shaped cross section, and is provided on the lower mold base 110 so as to be arranged adjacent to the pair of lower sliding portions 112. The frame 114 defines the fluid chamber 115 together with the upper surface of the lower mold base 110.

The partition plate 116 is housed in the fluid chamber 115. By the partition plate 116, the inside of the fluid chamber 115 is divided into a first fluid chamber 115a and a second fluid chamber 115b located on the pair of lower sliding portions 112 side of the first fluid chamber 115a. It is partitioned. The partition plate 116 is configured to be slidable in the fluid chamber 115 along the Y-axis direction. By sliding the partition plate 116 in the Y-axis direction, the volumes of the first fluid chamber 115a and the second fluid chamber 115b change. One end of the connecting member 117 is connected to one main surface of the partition plate 116, and the other end of the connecting member 117 is connected to a pair of lower sliding portions 112.

Further, a pair of first flow paths 118a and a pair of second flow paths 118b, which are flow paths for a working fluid, are formed in the lower mold base 110. One end of the pair of first flow paths 118a communicates with the first fluid chamber 115a of the pair of lower drive mechanisms 113, respectively. The other ends of the pair of first flow paths 118a are connected to the pair of fluid supply devices 105 via the pipe 119a, respectively. Similarly, one end of the pair of second flow paths 118b communicates with the second fluid chamber 115b of the pair of lower drive mechanisms 113, respectively. The other ends of the pair of second flow paths 118b are connected to the pair of fluid supply devices 105 via the pipe 119b, respectively.

Each fluid supply device 105 is a device that supplies a working fluid to the first fluid chamber 115a and the second fluid chamber 115b via the pipe 119a and the pipe 119b. The fluid supply device 105 can also recover the working fluid in the first fluid chamber 115a and the second fluid chamber 115b.

The pair of lower sliding portions 112 are attached to the lower mold base 110 so as to be movable in the Y-axis direction (left-right direction in FIG. 3). In one embodiment, a groove extending in the left-right direction is formed on the upper surface of the lower mold base 110. On the other hand, a rail that engages with the groove is formed on the lower surface of the pair of lower sliding portions 112. Therefore, for example, when the working fluid is supplied from the fluid supply device 105 into the first fluid chamber 115a, the pressure in the first fluid chamber 115a increases, so that the volume of the first fluid chamber 115a increases. The partition plate 116 moves in the Y-axis direction in the fluid chamber 115 so that the volume of the second fluid chamber 115b becomes small. On the contrary, when the working fluid is supplied from the fluid supply device 105 into the second fluid chamber 115b, the pressure in the second fluid chamber 115b increases, so that the volume of the first fluid chamber 115a in the Y-axis direction is increased. The partition plate 116 moves in the Y-axis direction in the fluid chamber 115 so that is smaller and the volume of the second fluid chamber 115b is larger. As the partition plate 116 moves in the fluid chamber 115 in this way, the pair of lower sliding portions 112 connected to the partition plate 116 is below the rail formed in the pair of lower sliding portions 112. In a state where the groove formed in the mold base 110 is engaged, the fluid moves in a direction approaching each other or in a direction away from each other. By individually changing the positions of the pair of lower sliding portions 112 in the Y-axis direction, the separation distance D1 of the pair of lower sliding portions 112 in the Y-axis direction is adjusted.

Further, on the lower surface of the upper die base 120, a pair of upper drive mechanisms 123 for driving the pair of upper sliding portions 122 are provided. Each of the pair of upper drive mechanisms 123 has a frame body 124. The frame body 124 has a U-shaped cross section, and is attached to the lower surface of the upper mold base 120 so as to be arranged adjacent to the pair of upper sliding portions 122. The frame body 124 defines the fluid chamber 125 together with the lower surface of the upper mold base 120.

The partition plate 126 is housed in the fluid chamber 125. The partition plate 126 divides the inside of the fluid chamber 125 into a first fluid chamber 125a and a second fluid chamber 125b located on the pair of upper sliding portions 122 side of the first fluid chamber 125a. Has been done. The partition plate 126 is configured to be slidable in the fluid chamber 125 along the Y-axis direction. By sliding the partition plate 116 in the Y-axis direction, the volumes of the first fluid chamber 115a and the second fluid chamber 115b change. One end of the connecting member 127 is connected to one main surface of the partition plate 126, and the other end of the connecting member 127 is connected to a pair of upper sliding portions 122.

Further, the upper die base 120 is formed with a pair of third flow paths 128a and a pair of fourth flow paths 128b, which are flow paths for the working fluid. One end of the pair of third flow paths 128a communicates with the first fluid chamber 125a of the pair of upper drive mechanisms 123, respectively. The other ends of the pair of third flow paths 128a are respectively connected to the pair of fluid supply devices 105 via the pipe 129a. Similarly, one end of the pair of fourth flow paths 128b communicates with the second fluid chamber 125b of the pair of upper drive mechanisms 123, respectively. The other ends of the pair of fourth flow paths 128b are connected to the pair of fluid supply devices 105 via the pipe 129b, respectively.

The fluid supply device 105 supplies the working fluid to the first fluid chamber 125a and the second fluid chamber 125b via the pipe 129a and the pipe 129b, or supplies the working fluid to the first fluid chamber 125a and the second fluid chamber 125b. It is possible to recover the working fluid from.

The pair of upper sliding portions 122 are attached to the upper mold base portion 120 so as to be movable in the Y-axis direction (left-right direction in FIG. 3). In one embodiment, a groove extending in the left-right direction is formed on the lower surface of the upper mold base 120. On the other hand, a rail that engages with the groove is formed on the upper surface of the pair of upper sliding portions 122. Therefore, for example, when the working fluid is supplied from the fluid supply device 105 into the first fluid chamber 125a, the pressure in the first fluid chamber 125a increases, so that the volume of the first fluid chamber 125a increases. The partition plate 126 moves in the Y-axis direction in the fluid chamber 125 so that the volume of the second fluid chamber 125b becomes smaller. On the contrary, when the working fluid is supplied from the fluid supply device 105 into the second fluid chamber 125b, the pressure in the second fluid chamber 125b increases, so that the volume of the first fluid chamber 125a becomes smaller. The partition plate 126 moves in the fluid chamber 125 so that the volume of the second fluid chamber 125b becomes large. As the partition plate 126 moves in the fluid chamber 125 in this way, the pair of upper sliding portions 122 connected to the partition plate 126 are formed on the pair of upper sliding portions 122 by the rail and the upper mold base. In a state of being engaged with the grooves formed in 120, they move in a direction approaching each other or in a direction away from each other. By individually changing the positions of the pair of upper sliding portions 122 in the Y-axis direction, the separation distance D2 of the pair of upper sliding portions 122 in the Y-axis direction is adjusted.

The pair of fluid supply devices 105 are connected to a control unit 70, which will be described later. By sending a control signal to the pair of fluid supply devices 105, the control unit 70 separates the pair of lower sliding portions 112 in the left-right direction and the pair of upper sliding portions 122 in the left-right direction. Control the distance D2. By adjusting the separation distances D1 and D2 in this way, the width of the main cavity portion MC in the Y-axis direction is adjusted.

Further, as shown in FIGS. 3A and 3B, the molding apparatus 10 further includes a first double acting die 130a and a second double acting die 130b. The first double-acting die 130a and the second double-acting die 130b have a plate shape and are provided along the XZ plane. The first double-acting mold 130a and the second double-acting mold 130b penetrate the lower mold base 110 and the upper mold base 120, respectively, so as to pass through the center lines of the lower mold 11 and the upper mold 12 in the Y-axis direction. And it is postponed. Hereinafter, when it is not necessary to distinguish between them, the first double-acting mold 130a and the second double-acting mold 130b are referred to as a pair of double-acting molds 130.

The pair of double-acting dies 130 are configured to be movable along the Z-axis direction (the direction in which the lower die 11 and the upper die 12 face each other). An actuator 134 is connected to the first double-acting die 130a (see FIG. 1), and the operation of the actuator 134 causes the first double-acting die 130a to move in the Z-axis direction. An actuator 132 is connected to the second double-acting die 130b (see FIG. 1), and the operation of the actuator 132 causes the second double-acting die 130b to move in the Z-axis direction. As shown in FIG. 3B, when the pair of double-acting dies 130 move in the Z-axis direction, the pair of double-acting dies 130 move forward and backward in the main cavity portion MC in the Z-axis direction.

See FIG. 1 again. As shown in FIG. 1, the heating mechanism 50 includes a power supply unit 55 and a bus bar 52 that electrically connects the power supply unit 55 and the electrodes 17 and 18. The power supply unit 55 includes a DC power supply and a switch, and can energize the metal pipe material 14 via 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 pipe material 14. Has been done. The bus bar 52 is connected to the lower electrodes 17 and 18 here.

In this heating mechanism 50, the direct current output from the power supply unit 55 is transmitted by the bus bar 52 and input to the electrode 17. Then, the direct current passes through the metal pipe material 14 and is input to the electrode 18. Then, the direct current is transmitted by the bus bar 52 and input to the power supply unit 55.

Each of the pair of gas supply mechanisms 40 includes a cylinder unit 42, a cylinder 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 tip of the cylinder rod 43 on the pipe holding mechanism 30 side. Has. The cylinder unit 42 is placed and fixed on the block 41. A tapered surface 45 is formed at the tip of the seal member 44 so as to be tapered, and is configured to fit the tapered concave surfaces 17b and 18b of the electrodes 17 and 18 (see FIGS. 2A and 2B). ). The seal member 44 extends from the cylinder unit 42 side toward the tip, and as shown in FIGS. 2 (a) and 2 (b), a gas passage through which the high-pressure gas supplied from the gas supply unit 60 flows. 46 is provided.

The gas supply unit 60 includes a gas source 61, an accumulator 62 for storing the gas supplied by the gas source 61, a first tube 63 extending from the accumulator 62 to the cylinder unit 42 of the gas supply mechanism 40, and a first tube 63 thereof. The pressure control valve 64 and the switching valve 65 interposed in the 1 tube 63, the second tube 67 extending from the accumulator 62 to the gas passage 46 formed in the seal member 44, and the second tube 67. It is composed of a pressure control valve 68 and a check valve 69 provided. The pressure control valve 64 serves to supply the cylinder unit 42 with a gas having an operating pressure adapted to the pushing force of the seal member 44 against the metal pipe material 14. The check valve 69 serves to prevent the high-pressure gas from flowing back in the second tube 67. The pressure control valve 68 interposed in the second tube 67 serves to supply a gas having an operating pressure for expanding the metal pipe material 14 to the gas passage 46 of the seal member 44 under the control of the control unit 70. Fulfill.

The control unit 70 can supply gas having a desired operating pressure into the metal pipe material 14 by controlling the pressure control valve 68 of the gas supply unit 60. Further, the control unit 70 acquires temperature information from the thermocouple 21 by transmitting information from (A) shown in FIG. 1, and controls the drive 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 that pumps up the water stored in the water tank 73, pressurizes it, and sends it to the cooling water passage 19 of the lower mold 11 and the cooling water passage 25 of the upper mold 12. It consists of a pipe 75. Although omitted, it is permissible to interpose a cooling tower for lowering the water temperature or a filter for purifying water in the pipe 75.

<Molding method of metal pipe using molding equipment>
Next, a method for forming a metal pipe according to the first embodiment will be described. This method is performed using the molding apparatus 10 shown in FIG. First, a hardenable steel grade cylindrical metal pipe material 14 is prepared. The metal pipe material 14 is placed (loaded) on the electrodes 17 and 18 provided on the lower mold 11 side by using, for example, a robot arm or the like. Since the concave grooves 17a and 18a are formed in the electrodes 17 and 18, the metal pipe material 14 is positioned by the concave grooves 17a and 18a. As a result, as shown in FIG. 4A, the metal pipe material 14 is arranged between the lower mold 11 and the upper mold 12.

Next, the control unit 70 controls the drive mechanism 80 and the pipe holding mechanism 30 to cause the pipe holding mechanism 30 to hold the metal pipe material 14. Specifically, the upper die 12 and the upper electrodes 17, 18 and the like held on the slide 81 side are moved to the lower die 11 side by driving the drive mechanism 80, and the upper electrode 17, which is included in the pipe holding mechanism 30. By operating an actuator that allows the 18th and lower electrodes 17 and 18 and the like to move forward and backward, the vicinity of both ends of the metal pipe material 14 is sandwiched by the pipe holding mechanism 30 from above and below. At this time, the metal pipe material 14 has the entire circumference near both ends of the metal pipe material 14 due to the presence of the concave grooves 17a and 18a formed in the electrodes 17 and 18 and the concave grooves formed in the insulating materials 91 and 101. It will be sandwiched in such a way that it is in close contact with the metal.

Subsequently, the control unit 70 heats the metal pipe 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 electric power. Then, the electric power transmitted to the lower electrodes 17 and 18 via the bus bar 52 is supplied to the upper electrodes 17 and 18 and the metal pipe material 14 sandwiching the metal pipe material 14, and exists in the metal pipe material 14. Due to the resistance, the metal pipe material 14 itself generates heat due to Joule heat. That is, the metal pipe material 14 is in an energized heating state.

Subsequently, as shown in FIG. 4B, the molding die 13 is closed with respect to the heated metal pipe material 14 by the control of the drive mechanism 80 by the control unit 70. As a result, the cavity 16 of the lower mold 11 and the cavity 24 of the upper mold 12 are combined, and the metal pipe material 14 is arranged and sealed in the main cavity portion MC between the lower mold 11 and the upper mold 12. Further, when the molding dies 13 are closed and the actuators 132 and 134 are operated, the pair of double-acting dies 130 move along the Z-axis direction and enter the main cavity portion MC. When the pair of double-acting dies 130 enter the main cavity MC, a part (first portion) 14a and 14b of the metal pipe material 14 arranged in the main cavity MC is in the Z-axis direction. It is crushed from both sides (the process of crushing the first part of the metal pipe material from the opposite direction). As a result, the parts 14a and 14b of the metal pipe material 14 project inward from the other part (second part) 14c of the metal pipe material 14 and are bent inward in the radial direction of the metal pipe material 14.

Next, as shown in FIG. 4B, the working fluid is supplied from the fluid supply device 105 to the first fluid chambers 115a and 125a, so that the side surfaces 112a2 and 112b2 of the pair of lower sliding portions 112 and The pair of lower sliding portions 112 and the pair of upper sliding portions 122 move so that the side surfaces 122a2 and 122b2 of the pair of upper sliding portions 122 come into contact with the outer peripheral surfaces of the metal pipe material 14. That is, the pair of lower sliding portions 112 and the pair of upper sliding portions 122 slide with respect to the lower mold base 110 and the upper mold base 120 so that the width of the main cavity MC in the Y-axis direction is narrowed. (A step of sliding the pair of upper sliding portions and the pair of lower sliding portions with respect to the upper mold base and the lower mold base, respectively). As a result, the separation distance D1 of the pair of lower sliding portions 112 and the separation distance D2 of the upper sliding portions 122 in the Y-axis direction become smaller (see FIG. 3A).

After that, by operating the cylinder unit 42 of the gas supply mechanism 40, the sealing member 44 is advanced to seal both ends of the metal pipe material 14 (see FIG. 2B). After the sealing is completed, high pressure gas is blown into the metal pipe material 14. Next, as shown in FIG. 4C, the pair of double acting dies 130 are retracted from the main cavity portion MC by operating the actuators 132 and 134 while blowing the high pressure gas into the metal pipe material 14.

Since the metal pipe material 14 is heated to a high temperature (around 950 ° C.) and softened, the gas supplied into the metal pipe material 14 thermally expands. Therefore, for example, the supplied gas is compressed air, and the metal pipe material 14 at 950 ° C. can be easily expanded by the thermally expanded compressed air. A part 14c of the metal pipe material 14 softened by heating due to the pressure of the thermally expanded gas is formed along the shape of the main cavity portion MC (a step of forming the second portion into the main body portion). At this time, a part 14a and 14b of the metal pipe material 14 crushed by the pair of double acting dies 130 and bent inside the metal pipe material 14 are crimped in a folded state, and the inside of the metal pipe material 14 is crimped. It is molded into the inner flange portion 104 extending to (a step of molding the first portion into the inner flange portion).

The outer peripheral surface of the blow-molded and swollen metal pipe material 14 contacts the cavity 16 of the lower mold 11 and is rapidly cooled, and at the same time, it contacts the cavity 24 of the upper mold 12 and is rapidly cooled (the upper mold 12 and the lower mold 11 are rapidly cooled. Since the heat capacity is large and the temperature is controlled to be low, when the metal pipe material 14 comes into contact with the metal pipe material 14, the heat on the pipe surface is taken away to the mold side at once) and quenching is performed. Such a cooling method is called mold contact cooling or mold cooling. Immediately after being rapidly cooled, austenite transforms into martensite (hereinafter, the transformation of austenite into martensite is referred to as martensite transformation). Since the cooling rate decreased in the latter half of cooling, martensite is transformed into another structure (troostite, sorbite, etc.) by reheating. Therefore, it is not necessary to perform a separate tempering process. Further, in the present embodiment, cooling may be performed by supplying a cooling medium, for example, into the cavity 24, instead of cooling the mold or in addition to cooling the mold. For example, until the temperature at which martensitic transformation begins, the metal pipe material 14 is brought into contact with the molds (upper mold 12 and lower mold 11) for cooling, and then the mold is opened and the cooling medium (cooling gas) is used as the metal pipe material. Martensitic transformation may be generated by spraying on 14.

The metal pipe 100 is obtained by performing blow molding on the metal pipe material 14 as described above and then cooling the metal pipe material 14.

FIG. 5 is a cross-sectional view of the metal pipe 100 molded by the molding method according to the above-described embodiment. As shown in FIG. 5, the metal pipe 100 is a steel metal pipe that is an integrally molded product, and has a main body portion 102 and a pair of inner flange portions 104. The main body 102 has a tubular shape, and a space S is defined inside the main body 102. The main body 102 is formed into a tubular shape by blowing high-pressure gas into the metal pipe material 14 and expanding a part 14c of the metal pipe material 14 along the shape of the wall surface defining the main cavity MC. ..

The pair of inner flange portions 104 project from the main body portion 102 to the inside of the metal pipe 100. That is, the pair of inner flange portions 104 extend from the main body portion 102 and are arranged in the space S. The pair of inner flange portions 104 are crushed by the pair of double acting dies 130, and the ends of parts 14a and 14b of the metal pipe material 14 (steel material) bent inside the metal pipe material 14 have high pressure. It is formed by crimping with the pressure of gas. In the embodiment shown in FIG. 5, the pair of inner flange portions 104 project (extend) from the main body portion 102 in a direction approaching each other.

By providing the pair of inner flange portions 104, the rigidity of the metal pipe 100 is increased. On the other hand, since the pair of inner flange portions 104 project inward of the main body portion 102, an increase in the external dimensions of the metal pipe 100 can be suppressed.

Next, a method for forming a metal pipe according to the second embodiment will be described. The method according to this embodiment is performed using a molding apparatus having substantially the same configuration as the molding apparatus 10 shown in FIG. However, this molding apparatus includes a molding die 13A instead of the molding die 13. The molding die 13A is different from the molding die 13 in that the first double acting die 130a is not provided. Hereinafter, the differences from the metal pipe molding method according to the first embodiment described above will be mainly described, and overlapping description will be omitted.

In the method according to the present embodiment, first, a cylindrical metal pipe material 14 of a hardenable steel grade is prepared. The metal pipe material 14 is placed (loaded) on the electrodes 17 and 18 provided on the lower mold 11 side by using, for example, a robot arm or the like. As a result, as shown in FIG. 6A, the metal pipe material 14 is arranged between the lower mold 11 and the upper mold 12.

Next, the control unit 70 controls the drive mechanism 80 and the pipe holding mechanism 30 to cause the pipe holding mechanism 30 to hold the metal pipe material 14. Specifically, the upper die 12 and the upper electrodes 17, 18 and the like held on the slide 81 side are moved to the lower die 11 side by driving the drive mechanism 80, and the upper electrode 17, which is included in the pipe holding mechanism 30. By operating an actuator that allows the 18th and lower electrodes 17 and 18 and the like to move forward and backward, the vicinity of both ends of the metal pipe material 14 is sandwiched by the pipe holding mechanism 30 from above and below.

Subsequently, the control unit 70 heats the metal pipe 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 electric power. Then, the electric power transmitted to the lower electrodes 17 and 18 via the bus bar 52 is supplied to the upper electrodes 17 and 18 and the metal pipe material 14 sandwiching the metal pipe material 14, and exists in the metal pipe material 14. Due to the resistance, the metal pipe material 14 itself generates heat due to Joule heat. That is, the metal pipe material 14 is in an energized heating state.

Subsequently, as shown in FIG. 6B, the molding die 13 is closed with respect to the heated metal pipe material 14 by the control of the drive mechanism 80 by the control unit 70. At this time, the molding die 13 is not completely closed, and is between the upper surface 112a1 of the first lower sliding portion 112a and the lower surface 122a1 of the first upper sliding portion 122a, and the second lower sliding portion. The upper die 12 moves to the lower die 11 side so that a gap is formed between the upper surface 112b1 of the moving portion 112b and the lower surface 122b1 of the second upper sliding portion 122b.

As the upper mold 12 moves in this way, it is between the bottom surface of the cavity 24 of the upper mold 12 (the surface that becomes the reference line LV1) and the bottom surface of the cavity 16 of the lower mold 11 (the surface that becomes the reference line LV2). The main cavity portion MC is formed in. Further, the upper surface 112a1 of the first lower sliding portion 112a and the lower surface 122a1 of the first upper sliding portion 122a communicate with the main cavity portion MC and have a smaller volume than the main cavity portion MC. The sub-cavity portion SC1 is formed. Similarly, between the upper surface 112b1 of the second lower sliding portion 112b and the lower surface 122b1 of the second upper sliding portion 122b, the volume communicates with the main cavity portion MC and has a volume larger than that of the main cavity portion MC. A small subcavity SC2 is formed. The subcavities SC1 and SC2 are spaces for forming a pair of outer flange portions 106 on the metal pipe.

As shown in FIG. 6B, when the molding die 13 is closed and the actuator 132 is operated at the same time, the second double acting die 130b moves along the Z-axis direction to move the main cavity portion MC. Enter inside. When the second double acting die 130b enters the main cavity MC, a part (first portion) 14a of the metal pipe material 14 arranged in the main cavity MC is moved upward (Z-axis direction). ) Is crushed. As a result, a part 14a of the metal pipe material 14 projects inward from the other part (second part) 14c of the metal pipe material 14 and is bent inward in the radial direction of the metal pipe material 14.

Next, as shown in FIG. 6B, the side surfaces 112a2, 112b2 of the pair of lower sliding portions 112 and the side surfaces 122a2, 122b2 of the pair of upper sliding portions 122 are formed on a part 14c of the metal pipe material 14. The pair of lower sliding portions 112 and the pair of upper sliding portions 122 move so as to come into contact with each other. That is, the pair of lower sliding portions 112 and the pair of upper sliding portions 122 slide with respect to the lower mold base 110 and the upper mold base 120 so that the width of the main cavity portion MC in the Y-axis direction is narrowed. .. As a result, the separation distance D1 of the pair of lower sliding portions 112 and the separation distance D2 of the upper sliding portions 122 in the Y-axis direction are reduced.

After that, by operating the cylinder unit 42 of the gas supply mechanism 40, the sealing member 44 is advanced to seal both ends of the metal pipe material 14 (see FIG. 2B). After the sealing is completed, the low pressure gas is blown into the metal pipe material 14. Since the metal pipe material 14 is heated to a high temperature (around 950 ° C.) and softened, the gas supplied into the metal pipe material 14 thermally expands. As a result, the part 14c of the metal pipe material 14 expands in the main cavity portion MC so as to follow the recesses 16 and 24, and the other parts (third part) 14d and 14e of the metal pipe material 14 are formed. , Expands so as to enter the subcavities SC1 and SC2, respectively.

Next, as shown in FIG. 6 (c), the second double acting die 130b is retracted from the main cavity portion MC by operating the actuator 132 while blowing the low pressure gas into the metal pipe material 14. At this time, a part 14a of the metal pipe material 14 that was crushed by the second double acting die 130b and bent inside the metal pipe material 14 was crimped in a folded state to the inside of the metal pipe material 14. The extending inner flange portion 104 is formed.

Next, the molding die 13 is further closed, and as shown in FIG. 6D, the main cavity portions MC and the sub-cavity portions SC1 and SC2 are further narrowed between the lower mold 11 and the upper mold 12. I will go. Further, a high-pressure gas having a higher pressure than the above-mentioned low-pressure gas is blown into the metal pipe material 14. As a result, as shown in FIG. 6D, the metal pipe material 14 is formed along the shape of the main cavity MC, and a part 14d, 14e of the metal pipe material 14 is folded outward. Each is crimped to form a pair of outer flange portions 106.

The outer peripheral surface of the blow-molded and swollen metal pipe material 14 contacts the cavity 16 of the lower mold 11 and is rapidly cooled, and at the same time, it contacts the cavity 24 of the upper mold 12 and is rapidly cooled (the upper mold 12 and the lower mold 11 are rapidly cooled. Since the heat capacity is large and the temperature is controlled to be low, when the metal pipe material 14 comes into contact with the metal pipe material 14, the heat on the pipe surface is taken away to the mold side at once) and quenching is performed. The metal pipe 100A is obtained by performing blow molding on the metal pipe material 14 as described above and then cooling the metal pipe material 14.

The metal pipe 100A formed by the method according to the second embodiment has a main body portion 102, an inner flange portion 104, and a pair of outer flange portions 106 (see FIG. 6D). The main body 102 has a tubular shape, and a space S is defined inside the main body 102. The main body 102 is formed into a tubular shape by blowing high-pressure gas into the metal pipe material 14 and expanding the metal pipe material 14 along the shape of the wall surface defining the main cavity MC.

The inner flange portion 104 projects from the main body portion 102 to the inside of the metal pipe 100A. That is, the inner flange portion 104 extends from the main body portion 102 and is arranged in the space S. The inner flange portion 104 is formed by being crushed by the second double acting die 130b and the end portion of the metal pipe material 14 bent inside the metal pipe material 14 being crimped.

The pair of outer flange portions 106 project from the main body portion 102 to the outside of the metal pipe 100. The pair of outer flange portions 106 are formed by crimping a part 14d, 14e of the metal pipe material 14 in a folded state in the subcavity portions SC1 and SC2. In the embodiment shown in FIG. 6D, the pair of outer flange portions 106 project from the main body portion 102 in a direction away from each other.

Next, the actions and effects of the metal pipes 100 and 100A according to the above embodiment will be described with reference to FIG. 7.

FIG. 7 is a cross-sectional view showing the metal pipes according to Examples 1 to 3 and Comparative Examples 1 and 2. The metal pipe SA1 shown in FIG. 7 is a metal pipe according to Comparative Example 1, and has a tubular main body 102 and a pair of outer flanges 106 extending outward from the main body 102. The main body 102 has a width of 46 mm in the y direction and a height of 28 mm in the x direction. The pair of outer flange portions 106 project 17 mm in the y direction from the main body portion 102. The metal pipe SA4 shown in FIG. 7 is a metal pipe according to Comparative Example 2, and is composed of only a tubular main body 102. The main body 102 has a width of 46 mm in the y direction and a height of 28 mm in the x direction.

The metal pipes SA2 and SA3 shown in FIG. 7 are the metal pipes according to the first and second embodiments, respectively. The metal pipes SA2 and SA3 have a tubular main body 102 and a pair of inner flanges 104 protruding inward from the main body 102. These main body portions 102 have the same dimensions as the main body portions 102 of the metal pipe SA1 and the metal pipe SA4. Further, the pair of inner flange portions 104 of the metal pipe SA2 are longer than the pair of inner flange portions 104 of the metal pipe SA3.

The metal pipe SA5 shown in FIG. 7 is a metal pipe according to the third embodiment, and is a pair of a tubular main body 102, an inner flange portion 104 protruding inward from the main body 102, and a pair protruding outward from the main body 102. It has an outer flange portion 106 of the above. The main body 102 of the metal pipe SA5 has the same dimensions as the main body 102 of the metal pipe SA1 and the metal pipe SA4. The outer flange portion 106 of the metal pipe SA5 has the same dimensions as the outer flange portion 106 of the metal pipe SA1.

FIG. 8 shows the moment of inertia of area and the section modulus of the metal pipes SA1 to SA5. Note that Ix in FIG. 8 indicates the moment of inertia of area for bending along the x direction shown in FIG. 7, and Iy indicates the moment of inertia of area for bending along the y direction. Similarly, Zx in FIG. 8 represents a cross-sectional coefficient for bending along the x direction and represents a cross-sectional coefficient for bending along the y direction.

From the results shown in FIG. 8, the metal pipes SA2 and SA3 (metal pipe with a pair of inner flange portions) according to the first and second embodiments are the metal pipe SA4 (metal pipe having only the main body portion) according to the comparative example 2. ), It has a higher moment of inertia of area Iy and a higher cross-sectional coefficient Zy, and it was confirmed that it has higher rigidity. Comparing the metal pipe SA2 and the metal pipe SA3, it was confirmed that the metal pipe SA2 having a longer inner flange portion 104 has a geometrical moment of inertia Iy and a cross-sectional coefficient Zy higher than those of the metal pipe SA3. It was.

On the other hand, it was confirmed that the moment of inertia of area Iy and the moment of inertia Zy of the metal pipes SA2 and SA3 are lower than the moment of inertia of area Iy and the moment of inertia Zy of the metal pipe SA1 according to Comparative Example 1. However, the external dimensions of the metal pipes SA2 and SA3 in the y direction were smaller than the external dimensions of the metal pipe SA1 in the y direction. From these results, it was confirmed that the metal pipes SA2 and SA3 according to the first and second embodiments can secure high rigidity without increasing the external dimensions.

Further, the metal pipe SA5 (metal pipe with an inner flange portion and a pair of outer flange portions) according to the third embodiment has a higher moment of inertia of area Iy and a cross-sectional coefficient Zy as compared with the metal pipes SA2 and SA3. It was confirmed that it had a higher rigidity.

Although the metal pipes and the molding methods thereof according to various embodiments have been described above, various modifications can be configured without changing the gist of the invention without being limited to the above-described embodiments.

For example, the metal pipe 100 shown in FIG. 5 has a pair of inner flange portions 104, but the metal pipe 100 can have an arbitrary number of inner flange portions. For example, three or more inner flange portions may be arranged in the space S of the metal pipe 100. Similarly, the metal pipe 100A may have only one outer flange portion 106 or may have three or more outer flange portions 106.

Further, the shape of the inner flange portion is not limited to that of the above-described embodiment, and various shapes can be adopted. For example, the inner flange portion may extend continuously along the longitudinal direction of the metal pipe 100, or a plurality of inner flanges may be arranged along the longitudinal direction of the metal pipe 100.

Further, although the metal pipe 100 shown in FIG. 5 has a main body portion 102 having a rectangular cross section, the main body portion 102 may have a different cross-sectional shape such as a circular shape. Further, in the embodiment shown in FIG. 3, a pair of fluid supply devices 105 are provided, but in one embodiment, one fluid supply device 105 is provided with respect to the pair of fluid chambers 115 and the pair of fluid chambers 125. The working fluid may be supplied.

10 ... Molding device, 11 ... Lower mold, 12 ... Upper mold, 13, 13A ... Molding mold, 14 ... Metal pipe material, 14a, 14b ... Part of metal pipe (first part), 14c ... Metal pipe Part (second part), 14d, 14e ... part of metal pipe (third part), 17, 18 ... electrode, 40 ... gas supply mechanism, 50 ... heating mechanism, 55 ... power supply part, 60 ... Gas supply part, 100, 100A ... Metal pipe, 102 ... Main body part, 104 ... Inner flange part, 106 ... Outer flange part, 110 ... Lower mold base, 112 ... Lower sliding part, 113 ... Lower drive mechanism, 120 ... Upper mold base, 122 ... Upper sliding part, 123 ... Upper drive mechanism, 130 ... Double acting mold, D1, D2 ... Separation distance, MC ... Main cavity part, SC1, SC2 ... Sub-cavity part.

Claims (6)

It is a steel metal pipe that is an integrally molded product.
A metal pipe including a tubular main body portion and an inner flange portion protruding from the main body portion to the inside of the main body portion. The metal pipe according to claim 1, wherein the inner flange portion is made of a steel material folded inward. Further provided with another inner flange portion protruding from the main body portion to the inside of the main body portion.
The metal pipe according to claim 1 or 2, wherein the inner flange portion and the other inner flange portion project from the main body portion in a direction approaching each other. The metal pipe according to any one of claims 1 to 3, further comprising an outer flange portion protruding from the main body portion to the outside of the main body portion. A molding method for molding a steel metal pipe having a tubular main body portion and an inner flange portion protruding inward from the main body portion by using a molding apparatus.
The molding device
A molding die having an upper mold and a lower mold and forming a main cavity portion for molding a metal pipe material between the upper mold and the lower mold.
A double-acting mold that can move forward and backward in the main cavity along the opposite direction of the upper mold and the lower mold.
A heating mechanism for heating the metal pipe material arranged in the main cavity portion, and
A gas supply unit that supplies gas into the heated metal pipe material,
With
The upper die is a pair of upper die sliding portions arranged apart from each other via the upper die base portion and the main cavity portion, and slides with respect to the upper die base portion so that the distance between them changes. Possible, including the pair of upper sliding portions,
The lower mold is a pair of lower sliding portions arranged apart from each other via the lower mold base portion and the main cavity portion, and slides against the lower mold base portion so that the separation distance from each other changes. Including the pair of movable lower sliding parts.
The molding method is
A step of allowing the double-acting die to enter the main cavity portion and crushing the first portion of the metal pipe material arranged in the main cavity portion from the opposite direction.
The upper die of the pair of upper sliding portions and the pair of lower sliding portions so that the separation distance of the pair of upper sliding portions and the separation distance of the pair of lower sliding portions are reduced. The process of sliding the base and the lower mold base, respectively,
By retracting the double-acting mold from the main cavity portion while supplying gas from the gas supply portion into the heated metal pipe material, the first portion of the metal pipe is displaced from the inner flange portion. And the process of molding the second part of the metal pipe into the main body,
Molding method, including. An outer flange portion in which the molding die communicates with the main cavity portion between the pair of upper sliding portions and the pair of lower sliding portions and protrudes from the main body portion to the outside of the main body portion. Further form a sub-cavity part for molding
5. The outer flange portion is formed by expanding a third portion of the metal pipe material in the sub-cavity by supplying a gas into the heated metal pipe material from the gas supply portion. The molding method described in 1.

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