FORMING DEVICE

Abstract

A forming device includes: a fluid supply unit that is disposed at an end portion of a metal pipe material and that supplies a fluid into the metal pipe material through an opening of the end portion; and a sealing mechanism that performs sealing against leakage of the fluid from the metal pipe material when the fluid is supplied by the fluid supply unit into the metal pipe material that is heated by a heating unit, in which the sealing mechanism performs the sealing by contact between the metal pipe material and a non-resin material, without applying an axial force to the metal pipe material.

Claims

1. A forming device comprising: a fluid supply unit that is disposed at an end portion of a metal pipe material and that supplies a fluid into the metal pipe material through an opening of the end portion; and a sealing mechanism that performs sealing against leakage of the fluid from the metal pipe material when the fluid is supplied by the fluid supply unit into the metal pipe material that is heated by a heating unit, wherein the sealing mechanism performs the sealing by contact between the metal pipe material and a non-resin material, without applying an axial force to the metal pipe material.

2. The forming device according to claim 1, wherein the fluid supply unit is disposed in an inner portion of the metal pipe material, and the sealing mechanism is disposed in at least one of the inner portion and an outer portion of the metal pipe material, and performs the sealing using a sealing surface moved by the sealing mechanism in a radial direction toward the metal pipe material when the fluid is supplied by the fluid supply unit.

3. The forming device according to claim 2, wherein the sealing mechanism includes a nozzle base member, a nozzle member that is provided on a front side of a shaft portion of the nozzle base member, a clamp mechanism that is provided on an outer peripheral portion of the nozzle member and that clamps the metal pipe material, and a hydraulic cylinder.

4. The forming device according to claim 1, further comprising: a holding unit for the sealing so that the metal pipe material does not buckle when the fluid is supplied by the fluid supply unit.

5. The forming device according to claim 4, further comprising: a forming die that forms a metal pipe from the metal pipe material and that includes a lower main die and an upper main die that are formed of a steel block.

6. The forming device according to claim 5, wherein the holding unit holds the metal pipe material disposed between the lower main die and the upper main die.

7. The forming device according to claim 4, wherein the holding unit includes a lower electrode and an upper electrode that interpose vicinities of end portions of the metal pipe material from an up-down direction.

8. The forming device according to claim 5, wherein the lower main die and the upper main die are provided with respective recessed portions in which the metal pipe material is accommodated, and in a state in which the lower main die and the upper main die are in close contact with each other, the respective recessed portions form a space having a target shape in which the metal pipe material is to be formed.

9. The forming device according to claim 5, further comprising: a drive mechanism that moves at least one of the lower main die and the upper main die.

10. The forming device according to claim 9, wherein the drive mechanism includes a slide that moves the upper main die so that the lower main die and the upper main die are joined together, a pull-back cylinder as an actuator that generates a force for pulling the slide upward, a main cylinder as a drive source that downward-pressurizes the slide, and a drive source that applies a driving force to the main cylinder.

11. The forming device according to claim 5, further comprising: a cooling unit that cools the forming die.

12. The forming device according to claim 11, wherein the cooling unit includes flow paths formed inside the lower main die and the upper main die, and a water circulation mechanism that supplies a cooling water to the flow paths and causes the cooling water to circulate through the flow paths.

13. The forming device according to claim 9, further comprising: a control unit that repeatedly performs an operation of forming the metal pipe material using the forming die.

14. The forming device according to claim 13, wherein the control unit closes the forming die by controlling the drive mechanism to lower the upper main die and bring the upper main die closer to the lower main die.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a schematic configuration view illustrating a forming device according to an embodiment of the present disclosure.

[0006] FIG. 2 is a perspective view illustrating a part of a nozzle.

[0007] FIG. 3 is a sectional view illustrating a sealing mechanism of the forming device according to the present embodiment.

[0008] FIG. 4 is a sectional view illustrating the sealing mechanism of the forming device according to the present embodiment.

[0009] FIG. 5 is a perspective view illustrating a collet.

[0010] FIG. 6 is a sectional view illustrating a sealing mechanism of a forming device according to a modification example.

DETAILED DESCRIPTION

[0011] Here, the above-described expansion forming device performs sealing using a resin material and supplies the fluid. However, in a case in which a temperature of the metal pipe material becomes high near a tip end (for example, in a case in which the metal pipe material is heated in a furnace), there is an issue in that the resin material is damaged during sealing.

[0012] It is desirable to provide a forming device for an expansion forming device that can perform sealing in a state in which an influence of a high-temperature metal pipe material is suppressed.

[0013] The forming device includes the sealing mechanism that performs sealing against the leakage of the fluid from the metal pipe material when the fluid is supplied by the fluid supply unit into the metal pipe material that is heated by the heating unit. Therefore, the fluid supplied from the fluid supply unit into the metal pipe material is prevented from leaking to the outside of the metal pipe material by the sealing of the sealing mechanism. Here, the sealing mechanism performs the sealing by contact between the metal pipe material and the non-resin material, without applying the axial force to the metal pipe material. As a result, it is possible to select a non-resin material having higher heat resistance than a sealing member such as a resin-based O-ring, as a material of the sealing mechanism. As a result, it is possible to perform sealing in a state in which the influence of the high-temperature metal pipe material is suppressed.

[0014] The fluid supply unit may be disposed in an inner portion of the metal pipe material, and the sealing mechanism may be disposed in at least one of the inner portion and an outer portion of the metal pipe material, and perform the sealing using a sealing surface moved by the sealing mechanism in a radial direction toward the metal pipe material when the fluid is supplied by the fluid supply unit. In this case, the sealing mechanism can press the sealing surface against the metal pipe material in the radial direction, and thus it is possible to more suppress the leakage of the fluid from the metal pipe material.

[0015] The forming device may further include a holding unit for the sealing so that the metal pipe material does not buckle when the fluid is supplied by the fluid supply unit. In a case in which the fluid supply unit is mounted in the metal pipe material, even when the pressing is performed with a certain pressing force, the holding unit can prevent the metal pipe material from moving in a pressing direction of the fluid supply unit. Alternatively, the holding unit can hold the metal pipe material transported from a transport device for the metal pipe material.

[0016] Hereinafter, a preferred embodiment of a forming device according to the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same portions or equivalent portions will be denoted by the same reference numerals, and the redundant description thereof will be omitted.

[0017] FIG. 1 is a schematic configuration view illustrating a forming device 1 according to the present embodiment. As illustrated in FIG. 1, the forming device 1 is a device that forms a metal pipe having a hollow shape by blow forming. In the present embodiment, the forming device 1 is installed on a horizontal plane. The forming device 1 includes a forming die 2, a drive mechanism 3, a holding unit 4, a fluid supply unit 6, a cooling unit 7, and a control unit 8. In addition, in the present specification, a metal pipe material 40 (metal material) refers to a hollow article before the completion of forming via the forming device 1. The metal pipe material 40 is a steel-type pipe material that can be quenched. Further, in a horizontal direction, a direction in which the metal pipe material 40 extends during the forming may be referred to as a longitudinal direction, and a direction perpendicular to the longitudinal direction may be referred to as a width direction.

[0018] The forming die 2 is a die that forms a metal pipe from the metal pipe material 40, and that includes a lower main die 11 (first main die) and an upper main die 12 (second main die) that face each other in an up-down direction. The lower main die 11 and the upper main die 12 are formed of a steel block. Each of the lower main die 11 and the upper main die 12 is provided with a recessed portion in which the metal pipe material 40 is accommodated. In a state in which the lower main die 11 and the upper main die 12 are in close contact with each other (die closed state), the respective recessed portions form a space having a target shape in which the metal pipe material is to be formed. Therefore, surfaces of the respective recessed portions are forming surfaces of the forming die 2. The lower main die 11 is fixed to a base stage 13 via a die holder or the like. The upper main die 12 is fixed to a slide of the drive mechanism 3 via a die holder or the like.

[0019] The drive mechanism 3 is a mechanism that moves at least one of the lower main die 11 and the upper main die 12. In FIG. 1, the drive mechanism 3 has a configuration of moving only the upper main die 12. The drive mechanism 3 includes a slide 21 that moves the upper main die 12 so that the lower main die 11 and the upper main die 12 are joined together, a pull-back cylinder 22 as an actuator that generates a force for pulling the slide 21 upward, a main cylinder 23 as a drive source that downward-pressurizes the slide 21, and a drive source 24 that applies a driving force to the main cylinder 23.

[0020] The holding unit 4 is a mechanism that holds the metal pipe material 40 disposed between the lower main die 11 and the upper main die 12. The holding unit 4 includes a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 on one end side in the longitudinal direction of the forming die 2, and a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 on the other end side in the longitudinal direction of the forming die 2. The lower electrodes 26 and the upper electrodes 27 on both sides in the longitudinal direction hold the metal pipe material 40 by interposing vicinities of end portions of the metal pipe material 40 from the up-down direction. Upper surfaces of the lower electrodes 26 and lower surfaces of the upper electrodes 27 are formed with groove portions having a shape corresponding to an outer peripheral surface of the metal pipe material 40. The lower electrode 26 and the upper electrode 27 can move in the up-down direction together with the movement of the fluid supply unit 6 in the up-down direction.

[0021] The fluid supply unit 6 is a mechanism that supplies a high-pressure fluid into the metal pipe material 40 held between the lower main die 11 and the upper main die 12. The fluid supply unit 6 supplies the high-pressure fluid into the metal pipe material 40 that is brought into a high-temperature state by being heated in a heating furnace or the like in a stage before the forming device, to expand the metal pipe material 40. The fluid supply unit 6 is provided on both end sides of the forming die 2 in the longitudinal direction. The fluid supply unit 6 includes a nozzle 31 that supplies the fluid from an opening portion of an end portion of the metal pipe material 40 to an inside of the metal pipe material 40, a drive mechanism 32 that moves the nozzle 31 forward and backward with respect to the opening portion of the metal pipe material 40, and a high-pressure fluid supply source 33 that supplies the high-pressure fluid into the metal pipe material 40 via the nozzle 31. The drive mechanism 32 brings the nozzle 31 into close contact with the end portion of the metal pipe material 40 in a state in which the sealing performance is ensured during the fluid supply and exhaust, and causes the nozzle 31 to be separated from the end portion of the metal pipe material 40 in other cases. The fluid supply unit 6 may supply a gas such as high-pressure air and an inert gas, as the fluid. In addition, the fluid supply unit 6 is the same device as the holding unit 4 including a mechanism that moves the metal pipe material 40 in the up-down direction.

[0022] Returning to FIG. 1, the cooling unit 7 is a mechanism that cools the forming die 2. The cooling unit 7 can rapidly cool the metal pipe material 40 when the expanded metal pipe material 40 comes into contact with the forming surface of the forming die 2, by cooling the forming die 2. The cooling unit 7 includes flow paths 36 formed inside the lower main die 11 and the upper main die 12 and a water circulation mechanism 37 that supplies a cooling water to the flow paths 36 and causes the cooling water to circulate through the flow paths 36.

[0023] The control unit 8 is a device that controls a part of the forming device 1. The control unit 8 controls the drive mechanism 3, the holding unit 4, and the fluid supply unit 6. The control unit 8 repeatedly performs the operation of forming the metal pipe material 40 using the forming die 2. In addition, the control unit 8 for the drive mechanism 3 and the control unit 8 for the holding unit 4 and the fluid supply unit 6 may be independent of each other. For example, in a case in which the holding unit 4 and the fluid supply unit 6 are newly added to an existing press device, the control unit 8 independent of the drive mechanism 3 is provided.

[0024] Specifically, the control unit 8 controls, for example, a transport timing from a transport device, such as a robot arm, to dispose the metal pipe material 40 between the lower main die 11 and the upper main die 12 in an open state. Alternatively, a worker may manually dispose the metal pipe material 40 between the lower main die 11 and the upper main die 12. Additionally, the control unit 8 controls an actuator of the holding unit 4 and the like so that the metal pipe material 40 is supported by the lower electrodes 26 on both sides in the longitudinal direction, and then the upper electrodes 27 are lowered to interpose the metal pipe material 40.

[0025] The control unit 8 closes the forming die 2 by controlling the drive mechanism 3 to lower the upper main die 12 and bring the upper main die 12 closer to the lower main die 11. Meanwhile, the control unit 8 controls the fluid supply unit 6 to seal the opening portions of both ends of the metal pipe material 40 with the nozzle 31 and supply the fluid. As a result, the metal pipe material 40, which is softened by the heating, expands and comes into contact with the forming surface of the forming die 2. Then, the metal pipe material 40 is formed to follow a shape of the forming surface of the forming die 2. In addition, in a case in which a metal pipe with a flange is formed, a part of the metal pipe material 40 is made to enter a gap between the lower main die 11 and the upper main die 12, and then die closing is further performed to crush the entering part to form a flange portion. When the metal pipe material 40 comes into contact with the forming surface, the metal pipe material 40 is quenched by being rapidly cooled by using the forming die 2 cooled by the cooling unit 7.

[0026] Hereinafter, a sealing mechanism 100 of the forming device 1 according to the present embodiment will be described in detail with reference to FIGS. 2 to 5. The sealing mechanism 100 is a mechanism that seals the metal pipe material 40 in the forming device 1 that is an expansion forming device that forms, by expansion, the metal pipe material 40. FIG. 2 is a perspective view illustrating the nozzle 31. The sealing mechanism 100 is provided at a tip end of the nozzle 31. The sealing mechanism 100 prevents the high-pressure fluid supplied from a flow path 63 from leaking from the metal pipe material 40 when the tip end of the nozzle 31 is mounted at the end portion of the metal pipe material 40.

[0027] As illustrated in FIGS. 2 and 3, the sealing mechanism 100 includes a nozzle base member 70, a nozzle member 71, a clamp mechanism 72, and a hydraulic cylinder 73. In addition, in the following description, a direction in which a center line CL of the nozzle 31 extends may be referred to as an axial direction D1. In the axial direction D1, a side of the metal pipe material 40, that is, a tip end side may be referred to as front, and an opposite side may be referred to as rear. In addition, the expression such as radial direction or circumferential direction may be used with reference to the center line CL.

[0028] The nozzle base member 70 is a base member for supporting various members in the nozzle 31. The nozzle base member 70 includes the flow path 63 that extends along the center line CL on the center line CL. The nozzle base member 70 includes a shaft portion 76 extending in the axial direction D1 along the center line CL and an extension portion 77 (see FIG. 2) that expands to an outer peripheral side in the radial direction on the rear side of the shaft portion 76.

[0029] The nozzle member 71 is a member disposed in an inner portion of the metal pipe material 40 when a gas is supplied to the metal pipe material 40. The nozzle member 71 is provided on the front side of the shaft portion 76 of the nozzle base member 70. A metal O-ring 79 is provided between the nozzle member 71 and the shaft portion 76. The metal O-ring 79 can also prevent damage due to heat even in a case in which the heated metal pipe material 40 and the nozzle member 71 come into contact with each other. The nozzle member 71 has a cylindrical shape. The flow path 63 is formed on the center line CL of the nozzle member 71. The flow path 63 is open at a front end surface 71a of the nozzle member 71. Therefore, the fluid is supplied from the front end surface 71a of the nozzle member 71 into the metal pipe material 40. An outer peripheral surface 71b of the nozzle member 71 is designed to have a small gap between the outer peripheral surface 71b and an inner peripheral surface of the metal pipe material 40.

[0030] The clamp mechanism 72 is a mechanism that is provided on an outer peripheral portion of the nozzle member 71 and that clamps the metal pipe material 40. The clamp mechanism 72 seals the metal pipe material 40 by deforming the clamp mechanism 72 itself in the radial direction. In the present embodiment, the clamp mechanism 72 clamps the metal pipe material 40 by contracting in response to an external force applied from the outer peripheral side. The clamp mechanism 72 is disposed at a position corresponding to the nozzle member 71 and the shaft portion 76 of the nozzle base member 70 in the axial direction D1. The clamp mechanism 72 is a tubular body including a plurality of slits 84A and 84B, and includes a collet 80 that is contractible and restorable in the radial direction. A detailed configuration of the collet 80 will be described below.

[0031] The hydraulic cylinder 73 includes a cylinder main body 90 and a cylinder rod 91. The cylinder main body 90 is disposed on the outer peripheral side with respect to the clamp mechanism 72. The cylinder main body 90 is fixed to the extension portion 77 of the nozzle base member 70. The cylinder rod 91 is disposed between the clamp mechanism 72 and the cylinder main body 90 in the radial direction. In addition, a front region of the cylinder rod 91 in the axial direction D1 is disposed to be in contact with the clamp mechanism 72 on the inner peripheral surface. The cylinder rod 91 includes a tapered surface 96 on an inner peripheral surface on a front end side. The tapered surface 96 is inclined toward the outer peripheral side from the front side to the rear side. In addition, a rear region of the cylinder rod 91 in the axial direction D1 is inserted into a guide groove portion 78 of the extension portion 77 of the nozzle base member 70 to be capable of reciprocating motion.

[0032] A hydraulic chamber 93 (see FIG. 3) and a hydraulic chamber 94 (see FIG. 4) are formed between the cylinder main body 90 and the cylinder rod 91. The hydraulic chamber 93 is disposed on the rear side with respect to the hydraulic chamber 94. A hydraulic oil OL1 is supplied to the hydraulic chamber 93 from a hydraulic flow path L1 of the cylinder main body 90. As a result, the cylinder rod 91 moves to the front side by a hydraulic pressure of the hydraulic oil OL1. The hydraulic oil OL2 (see FIG. 4) is supplied to the hydraulic chamber 94 from a hydraulic flow path L2 of the cylinder main body 90. As a result, the cylinder rod 91 moves to the rear side by a hydraulic pressure of the hydraulic oil OL2. A plurality of sealing members such as an O-ring are provided between the cylinder rod 91 and the cylinder main body 90. In addition, the plurality of sealing members are provided between the cylinder rod 91 and the guide groove portion 78.

[0033] The collet 80 will be described with reference to FIG. 5. As illustrated in FIG. 5, the collet 80 includes a tubular main body 81, a front end portion 82 on the front side in the axial direction D1, and a rear end portion 83 on the rear side in the axial direction D1. The plurality of slits 84A and 84B extending in the axial direction D1 are formed in the main body 81. The slits 84A and 84B penetrate the main body 81 in the radial direction, and extend over the entire main body 81 in the axial direction D1. The slits 84A and 84B are alternately disposed in the circumferential direction. The slit 84A is formed in the main body 81 and the rear end portion 83 and is not formed in the front end portion 82. Therefore, at the position of the slit 84A, the collet 80 is divided in the circumferential direction at the rear end portion 83, and is connected in the circumferential direction at the front end portion 82. The slit 84B is formed in the main body 81 and the front end portion 82 and is not formed in the rear end portion 83. Therefore, at the position of the slit 84B, the collet 80 is divided in the circumferential direction at the front end portion 82, and is connected in the circumferential direction at the rear end portion 83.

[0034] As described above, the collet 80 has a structure in which a plurality of tube walls are connected to each other in a strip shape in the circumferential direction. When the external force is applied to the collet 80 from the outer peripheral side, the collet 80 is deformed so that the gap between the slits 84A and 84B is crushed. Therefore, the collet 80 is deformed to contract in the radial direction as the circumferential length decreases. Meanwhile, when the external force is released, the respective slits 84A and 84B return to an original gap size due to an elastic action of a spring. Therefore, the collet 80 is automatically restored to an original shape.

[0035] The collet 80 includes a tapered structure 86 provided on the front side and a tapered structure 87 provided on the rear side. The tapered structure 86 is provided on an outer peripheral surface side of the collet 80. The tapered structure 86 is inclined to widen toward the outer peripheral side from the front end portion 82 to the rear side. The tapered structure 87 is inclined to widen toward the outer peripheral side from the rear end portion 83 to the front side. As a result, the collet 80 is deformed in the radial direction in response to the external force applied through the tapered structures 86 and 87 as the cylinder rod 91 moves to the rear side in the axial direction D1. The modification aspect will be described below. An outer peripheral surface 80b of the collet 80 between the tapered structures 86 and 87 extends parallel to the axial direction D1. The collet 80 is a member made of metal. Heat-resistant spring steel is preferably used as the metal material. Therefore, when the clamp mechanism 72 is made of metal, the clamp mechanism 72 can seal the metal pipe material 40 by the metal touch during the clamping.

[0036] The dispositions of the collet 80 in the sealing mechanism 100 will be described with reference to FIGS. 3 and 4. An inner peripheral surface 80a of the collet 80 is disposed to face the outer peripheral surface 71b of the nozzle member 71 and an outer peripheral surface 76a of the shaft portion 76 of the nozzle base member 70 in the radial direction. The tapered structure 86 on the front side is disposed to make surface contact with the tapered surface 96 of the cylinder rod 91. The tapered structure 87 on the rear side is disposed to make surface contact with the tapered surface 75a formed on the nozzle base member 70. In addition, a restricting surface 75b that restricts the movement of the collet 80 is formed on an inner side of the tapered surface 75a of the nozzle base member 70.

[0037] A clamping/sealing mode by the clamp mechanism 72 using the collet 80 will be described. A state illustrated in FIG. 3 is a state before the clamping. In this state, the collet 80 is in a non-contraction state. When the hydraulic oil OL2 is supplied to the hydraulic chamber 94 from this state, the cylinder rod 91 moves to the rear side as illustrated in FIG. 4. The cylinder rod 91 moves the entire collet 80 that is in contact with the tapered structure 86 to the rear side. The collet 80 is guided by the tapered surface 75a and moves rearward to the position of the restricting surface 75b. Here, the collet 80 moves to the rear side in a state of being in contact with the tapered surface 75a at a location of the tapered structure 87.

[0038] Therefore, the collet 80 receives the external force that acts from the outer peripheral side toward the inner peripheral side via the tapered structure 87, from the tapered surface 75a. As a result, the collet 80 is deformed to contract toward the inner peripheral side as the slits 84A and 84B are narrowed. In addition, the collet 80 moves to the rear side in a state of being in contact with the tapered surface 96 at a location of the tapered structure 86. Therefore, the collet 80 receives the external force that acts from the outer peripheral side toward the inner peripheral side via the tapered structure 86, from the tapered surface 96. As a result, the collet 80 is deformed to contract toward the inner peripheral side as the slits 84A and 84B are narrowed.

[0039] In this way, the collet 80 contracts to the inner peripheral side, and thus the collet 80 can clamp the metal pipe material 40 between the collet 80 and the nozzle member 71. In such a case, the gap between the slits 84A and 84B of the collet 80 is reduced. The metal pipe material 40 is deformed by the clamping, and the inner peripheral surface of the metal pipe material 40 and the outer peripheral surface 71b of the nozzle member 71 come into close contact with each other, so that the metal pipe material 40 is in a sealed state so that a high-pressure airflow from the inside to the outside of the metal pipe material 40 is not leaked.

[0040] When the forming of the metal pipe material 40 is completed, as illustrated in FIG. 3, the hydraulic oil OL1 is supplied to the hydraulic chamber 93 to move the cylinder rod 91 to the front side. In such a case, the external force acting on the collet 80 is released. The collet 80 is restored and expanded in diameter by the spring action. In such a case, the entire collet 80 moves to an original position on the front side such that the collet 80 is guided by the tapered structure 87 as the collet 80 is expanded in diameter.

[0041] The nozzle base member 70 can supply cooling air to the collet 80 through a path formed by the flow path L3 with respect to the restricting surface 75b or a path using the guide groove portion 78. In addition, the collet 80 includes the plurality of slits 84A and 84B extending substantially over the entire axial direction D1. Therefore, in a state in which a heat transfer area is widened by the plurality of slits 84A and 84B, the cooling using the cooling air is performed.

[0042] Hereinafter, the operations and effects of the forming device 1 according to the present embodiment will be described.

[0043] In the sealing mechanism 100, the nozzle member 71 is disposed in the inner portion of the metal pipe material 40, and the clamp mechanism 72 is provided on the outer peripheral side of the nozzle member 71. Therefore, the fluid supplied from the nozzle member 71 into the metal pipe material 40 is prevented from leaking to the outside of the metal pipe material 40 by the sealing of the clamp mechanism 72. Here, the clamp mechanism 72 seals the metal pipe material 40 by deforming the clamp mechanism 72 itself in the radial direction. Since the mechanism itself for clamping the metal pipe material 40 is deformed to perform the sealing, it is possible to select a material having higher heat resistance than a sealing member such as a resin-based O-ring, as a material of the clamp mechanism 72. As a result, it is possible to perform sealing in a state in which the influence of the high-temperature metal pipe material 40 is suppressed.

[0044] For example, in a case in which the metal pipe material 40 is heated only by the energization heating, the sealing using the O-ring in the related art can also be used because the temperature on the end portion side with respect to the electrode does not reach a high level, but, in the heating method in which the entire metal pipe material 40 including the end portion is heated to a high temperature by the furnace heating, it is difficult to use the O-ring. In contrast, in the present invention, even when the furnace heating is performed, it is possible to perform high-quality sealing.

[0045] The clamp mechanism 72 may clamp the metal pipe material 40 by contracting in response to the external force applied from the outer peripheral side. As a result, the clamp mechanism can be configured with a simple design.

[0046] The clamp mechanism 72 may seal the metal pipe material 40 by the metal touch during the clamping by forming the clamp mechanism 72 with metal. As a result, it is possible to perform sealing in a state in which the influence of the high-temperature metal pipe material 40 is suppressed.

[0047] The clamp mechanism 72 may be a tubular body including the plurality of slits 84A and 84B, and include the collet 80 that is contractible and restorable in the radial direction. In this case, the clamping and the sealing can be performed with a simple structure.

[0048] The clamp mechanism 72 may include tapered structures 86 and 87, and may be deformed in the radial direction in response to the external force applied via the tapered structures 86 and 87 as the clamp mechanism 72 moves in the axial direction D1. In this case, the operation of the clamp mechanism 72 that moves in the axial direction D1 can be easily converted into the external force for deforming the clamp mechanism 72 in the radial direction.

[0049] In addition, the forming device 1 includes the sealing mechanism 100 that performs the sealing against the leakage of the fluid from the metal pipe material 40 when the fluid is supplied by the fluid supply unit 6 into the metal pipe material 40 that is heated by the heating unit (here, external heating furnace). Therefore, the fluid supplied from the fluid supply unit 6 into the metal pipe material 40 is prevented from leaking to the outside of the metal pipe material 40 by the sealing of the sealing mechanism 100. Here, the sealing mechanism 100 performs the sealing by contact between the metal pipe material 40 and the non-resin material, without applying the axial force to the metal pipe material 40. As a result, it is possible to select a non-resin material having higher heat resistance than a sealing member such as a resin-based O-ring, as a material of the sealing mechanism 100. As a result, it is possible to perform sealing in a state in which the influence of the high-temperature metal pipe material 40 is suppressed.

[0050] The nozzle member 71 of the fluid supply unit 6 may be disposed in the inner portion of the metal pipe material 40, and the collet 80 of the sealing mechanism 100 may be disposed on the outer portion of the metal pipe material 40, and perform the sealing using the inner peripheral surface 80a that is the sealing surface moved by the sealing mechanism 100 in the radial direction toward the metal pipe material 40 when the fluid is supplied by the fluid supply unit 6. In this case, the sealing mechanism 100 can press the sealing surface against the metal pipe material 40 in the radial direction, and thus it is possible to more suppress the leakage of the fluid from the metal pipe material 40.

[0051] The forming device 1 may further include the holding unit 4 for the sealing so that the metal pipe material 40 does not buckle when the fluid is supplied by the fluid supply unit 6. In a case in which the nozzle member 71 of the fluid supply unit 6 is mounted in the metal pipe material 40, even when the pressing is performed with a certain pressing force, the holding unit 4 can prevent the metal pipe material 40 from shifting in the pressing direction of the nozzle member 71 of the fluid supply unit 6. Alternatively, the holding unit 4 can hold the metal pipe material 40 transported from a transport device for the metal pipe material 40.

[0052] The present invention is not limited to the above-described embodiment.

[0053] For example, the clamp mechanism 72 may clamp the metal pipe material 40 by expanding in response to the external force applied from the inner peripheral side. As a result, a compact configuration with a small diameter can be obtained.

[0054] In addition, the clamp mechanism 72 is not limited to the mechanism including the collet 80, and can be changed as appropriate as long as the mechanism can perform the clamping and the sealing.

[0055] In addition, the structure of the sealing mechanism 100 is not limited to the structures in FIGS. 3 and 4, and various structures may be changed as appropriate.

[0056] In addition, in the above-described embodiment, the furnace heating is adopted as the method of heating the metal pipe material, but the energization heating using the electrode may be adopted.

[0057] In addition, as the sealing mechanism, a sealing mechanism 100 illustrated in FIG. 6 may be adopted. The sealing mechanism 100 illustrated in FIG. 6 is different from the above-described embodiment in that the sealing mechanism 100 does not include the clamp mechanism 72 and performs the sealing from the inner side of the metal pipe material 40. The nozzle 31 includes a nozzle base member 170 and the nozzle member 171. The nozzle member 171 is inserted into the opening of the metal pipe material 40 being held by the electrodes 26 and 27. Here, a tapered surface 40a is formed on the inner peripheral surface of the end portion of the metal pipe material 40. The tapered surface 40a is inclined so that an inner diameter increases toward the tip end. The tapered surface 40a may be formed by being processed in advance. In contrast, the outer peripheral surface of the nozzle member 171 includes a tapered surface 171b. The tapered surface 171b is inclined so that an outer diameter decreases from the rear side toward the front side. An inclination angle of the tapered surface 171b is the same as an inclination angle of the tapered surface 40a. When the nozzle member 171 is inserted into the metal pipe material 40, the tapered surface 171b comes into surface contact with the tapered surface 40a, and thus the sealing is performed. When the nozzle member 171 moves to the front side, the inclined tapered surface 171b, which is the sealing surface, moves relatively outward in the radial direction toward the metal pipe material 40, and thus the sealing is performed. The nozzle member 171 is made of the non-resin material such as the metal material. Therefore, the tapered surface 171b, which is the sealing surface, is also made of the non-resin material.

[0058] When the high-pressure fluid is supplied into the metal pipe material 40, the metal pipe material 40 heated to a high temperature is used, and thus the metal material is in a softened state. In general, in a case in which a long pipe material is heated to a high temperature, a length change of 0.1% occurs in 1 m of a metal pipe material per 100 C. due to thermal expansion. In a case in which the high-pressure fluid is supplied into the metal pipe material 40, the metal pipe material 40 shortens as the temperature of the metal pipe material 40 continuously decreases, so that the control unit 8 performs predetermined control on the nozzle 31 so that the tapered surfaces 40a and 171b are not separated from each other.

[0059] In order to prevent the tapered surface 40a of the metal pipe material 40 and the tapered surface 171b of the nozzle member 171 from being separated from each other, it is necessary to perform control of variably applying an appropriate thrust force with respect to the pressing force of the nozzle member 171, in accordance with the pressure of the high-pressure fluid in the metal pipe material 40. As described above, since the metal pipe material 40 is softened by the heating, when an excessive pressing force is applied, the metal pipe material 40 may be accompanied by a buckling phenomenon, or the nozzle member 171 may be excessively inserted into the metal pipe material 40. Meanwhile, in a case in which the pressing force is small, the nozzle member 171 retreats due to the internal pressure when the high-pressure fluid is supplied, and the tapered surfaces 40a and 171b are separated from each other. Therefore, the control unit 8 performs control of varying the pressing force of the nozzle member 171 in real time in accordance with the internal pressure.

[0060] Meanwhile, a mechanism for firmly clamping and fixing the metal pipe material 40 itself may be considered so that the nozzle member 171 may be pressed against the end portion of the metal pipe material 40 with an excessive pressing force, but, even when the metal pipe material 40 softened by the heating is attempted to be gripped not to move by firmly clamping the metal pipe material 40, the metal pipe material 40 itself is deformed, so that the metal pipe material 40 cannot be clamped to overcome the pressing force of the nozzle member 171. Therefore, the control unit 8 controls the pressing force of the nozzle member 171 in accordance with the internal pressure of the high-pressure fluid.

[0061] In a case in which the pressure of the high-pressure fluid is removed after the expansion forming is completed, it is necessary, conversely, to weaken the pressing force of the nozzle member 171 in accordance with the internal pressure. In a case in which the control unit 8 does not perform control of weakening the pressing force, the pressing force on the tapered surface 40a of the end portion of the metal pipe material 40 is increased, and the nozzle member 171 is fitted to the metal pipe material 40. Therefore, the control unit 8 performs the control of weakening the pressing force of the nozzle member 171.

[0062] Alternatively, the control unit 8 may perform position control of fixing the position of the nozzle member 171 at a position that is always constant.

[0063] From the above, the forming device 1 includes the sealing mechanism 100 that performs the sealing against the leakage of the fluid from the metal pipe material 40 when the fluid is supplied by the fluid supply unit 6 into the metal pipe material 40 that is heated by the heating unit (here, external heating furnace). Therefore, the fluid supplied from the fluid supply unit 6 into the metal pipe material 40 is prevented from leaking to the outside of the metal pipe material 40 by the sealing of the sealing mechanism 100. Here, the sealing mechanism 100 performs the sealing by contact between the metal pipe material 40 and the tapered surface 171b of the nozzle member 171 that is the non-resin material, without applying the axial force to the metal pipe material 40. As a result, it is possible to select a non-resin material having higher heat resistance than a sealing member such as a resin-based O-ring, as a material of the sealing mechanism 100. As a result, it is possible to perform sealing in a state in which the influence of the high-temperature metal pipe material 40 is suppressed.

[0064] The nozzle member 171 of the fluid supply unit 6 may be disposed in the inner portion of the metal pipe material 40, and the tapered surface 171b of the nozzle member 171 of the sealing mechanism 100 may be disposed in the inner portion of the metal pipe material 40, and perform the sealing using the tapered surface 171b that is the sealing surface moved by the sealing mechanism 100 in the radial direction toward the metal pipe material 40 when the fluid is supplied by the fluid supply unit 6. In this case, the sealing mechanism 100 can press the sealing surface against the metal pipe material 40 in the radial direction, and thus it is possible to more suppress the leakage of the fluid from the metal pipe material 40.

[0065] The forming device 1 may further include the holding unit 4 for the sealing so that the metal pipe material 40 does not buckle when the fluid is supplied by the fluid supply unit 6. In a case in which the nozzle member 171 of the fluid supply unit 6 is mounted in the metal pipe material 40, even when the pressing is performed with a certain pressing force, the holding unit 4 can prevent the metal pipe material 40 from shifting in the pressing direction of the nozzle member 171 of the fluid supply unit 6. Alternatively, the holding unit 4 can hold the metal pipe material 40 transported from a transport device for the metal pipe material 40.

ASPECT 1

[0066] A sealing mechanism that seals a metal pipe material in an expansion forming device that forms, by expansion, the metal pipe material, the sealing mechanism including: a nozzle member that is disposed in an inner portion of the metal pipe material; and a clamp mechanism that is provided on an outer peripheral portion of the nozzle member and that clamps the metal pipe material, in which the clamp mechanism seals the metal pipe material by deforming the clamp mechanism itself in a radial direction.

ASPECT 2

[0067] The sealing mechanism according to aspect 1, in which the clamp mechanism clamps the metal pipe material by contracting in response to an external force applied from an outer peripheral side.

ASPECT 3

[0068] The sealing mechanism according to aspect 1, in which the clamp mechanism clamps the metal pipe material by expanding in response to an external force applied from an inner peripheral side.

ASPECT 4

[0069] The sealing mechanism according to aspect 1, in which the clamp mechanism is made of metal, and the clamp mechanism seals the metal pipe material by metal touch during the clamping.

ASPECT 5

[0070] The sealing mechanism according to aspect 1, in which the clamp mechanism is a tubular body including a plurality of slits, and includes a collet that is contractible and restorable in the radial direction.

ASPECT 6

[0071] The sealing mechanism according to aspect 1, in which the clamp mechanism includes a tapered structure, and is deformed in the radial direction in response to an external force applied via the tapered structure as the clamp mechanism moves in an axial direction.

[0072] It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.