FORMING DEVICE

Abstract

A forming device that forms a metal member from a metal material of an aluminum alloy, the forming device includes: a forming die that is curved to be recessed in a cross-sectional view and that includes a corner portion forming surface for forming a corner portion of the metal member, in which the forming die includes a first main die and a second main die that face each other, and a double-action die that is movable relative to the first main die and the second main die, and the metal material is pressed by the double-action die such that a corner portion corresponding part corresponding to the corner portion in the metal material is pushed against the corner portion forming surface.

Description

BACKGROUND

Technical Field

A certain embodiment of the present disclosure relates to a forming device.

Description of Related Art

In the related art, a forming device that forms a metal material has been known. For example, the related art discloses a forming device including a die including a lower die and an upper die that are paired with each other. In such a forming device, a metal material is brought into contact with a forming surface inside the die, thereby forming a metal member having a shape corresponding to the forming surface.

SUMMARY

According to an embodiment of the present invention, there is provided a forming device that forms a metal member from a metal material of an aluminum alloy, the forming device including: a forming die that is curved to be recessed in a cross-sectional view and that includes a corner portion forming surface for forming a corner portion of the metal member, in which the forming die includes a first main die and a second main die that face each other, and a double-action die that is movable relative to the first main die and the second main die, and the metal material is pressed by the double-action die such that a corner portion corresponding part corresponding to the corner portion in the metal material is pushed against the corner portion forming surface.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 2A is a schematic side view illustrating a heating and expanding unit. FIG. 2B is a sectional view illustrating a state where a nozzle has sealed a metal pipe material.

FIGS. 3A and 3B are schematic sectional views of a forming die.

FIGS. 4A to 4F are schematic sectional views illustrating a state of the forming die at each timing.

FIG. 5 is a graph illustrating temporal changes in a position of a main die, a position of a double-action die, and a pressure of air blow on the metal pipe material.

FIGS. 6A to 6F are schematic sectional views illustrating a state of the forming die at each timing.

FIG. 7 is a graph illustrating temporal changes in the position of the main die, the position of the double-action die, and the pressure of the air blow on the metal pipe material.

FIGS. 8A to 8C are schematic sectional views illustrating a state of the forming die at each timing.

FIG. 9 is a graph illustrating temporal changes in the position of the main die, the position of the double-action die, and the pressure of the air blow on the metal pipe material.

FIG. 10 is a schematic sectional view illustrating a forming die according to a modification example.

FIG. 11 is a graph illustrating a relationship between a plate thickness and a forming limit of a corner portion.

DETAILED DESCRIPTION

An aluminum alloy may be used as the metal material for weight saving. Since the strength of the aluminum alloy is lower than the strength of a steel material, it is required to use a metal material having a large plate thickness in order to secure the strength. Here, the forming die has a corner portion forming portion that is curved to be recessed in a cross-sectional view and forms a corner portion of the metal member. In a case where the plate thickness of the metal material is large, it is difficult to form the corner portion of the metal member into a shape corresponding to the corner portion forming portion.

Therefore, it is desirable to provide a forming device that can form a corner portion of a metal member of an aluminum alloy after forming, into a desired shape.

The forming device includes the forming die that is curved to be recessed in a cross-sectional view and that includes the corner portion forming surface for forming the corner portion of the metal member. In a case where a plate thickness of the metal material of the aluminum alloy is large, the deformation resistance is large, and the corner portion corresponding part is less likely to be deformed along a shape of the corner portion forming surface. In contrast, the forming die includes the double-action die that is movable relative to the first main die and the second main die. The forming device presses the metal material by the double-action die such that the corner portion corresponding part is pushed against the corner portion forming surface. In this case, the pushed corner portion corresponding part is bent into a shape along the corner portion forming surface. In this state, the corner portion corresponding part is easily deformed into a shape along the corner portion forming surface even when the deformation resistance is large. As a result, the corner portion of the metal member of the aluminum alloy after forming can be formed into a desired shape.

The double-action die may push the corner portion corresponding part against the corner portion forming surface in a stage before the first main die and the second main die move to a mold clamping position. In this case, the corner portion corresponding part can be brought closer to the corner portion forming surface in a stage before the metal member is completed by moving the first main die and the second main die to the mold clamping position. Therefore, at the time of completion of the metal member, the corner portion having a shape along the corner portion forming surface is easily formed.

The double-action die may be movable in a second direction intersecting a first direction in which the first main die and the second main die face each other in a cross-sectional view, and the double-action die may press a part different from the corner portion corresponding part in the metal material. In this case, the double-action die presses the metal material from the second direction, so that a portion of the metal material near the corner portion corresponding part is pushed out to the main die side. As a result, the corner portion corresponding part is bent to be pushed against the corner portion forming surface.

The double-action die may include the corner portion forming surface, and may press the corner portion forming surface against the corner portion corresponding part. In this case, the metal material is bent such that the vicinity of the corner portion corresponding part of the metal material has a shape along the corner portion forming surface of the double-action die.

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

FIG. 1 is a schematic configuration view of 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 heating unit 5, a fluid supply unit 6, a cooling unit 7, and a control unit 8. 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. In addition, 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”.

The forming die 2 is a die that forms a metal pipe 41 (FIG. 3B) from the metal pipe material 40, and 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 where the lower main die 11 and the upper main die 12 are in close contact with each other (die closed state), the respective recessed parts form a space having a target shape in which the metal pipe material is to be formed. Therefore, surfaces of the respective recessed parts 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.

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 such 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 applies a downward pressure to the slide 21, and a drive source 24 that applies a driving force to the main cylinder 23.

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. Drive mechanisms (not illustrated) are provided in the lower electrodes 26 and the upper electrodes 27 and are movable independently of each other in the up-down direction.

The heating unit 5 heats the metal pipe material 40. The heating unit 5 is a mechanism that heats the metal pipe material 40 by energizing the metal pipe material 40. The heating unit 5 heats the metal pipe material 40 in a state where the metal pipe material 40 is spaced apart from the lower main die 11 and the upper main die 12, between the lower main die 11 and the upper main die 12. The heating unit 5 includes the lower electrodes 26 and the upper electrodes 27 on both sides in the longitudinal direction, and a power supply 28 that causes a current to flow through the metal pipe material 40 via the electrodes 26 and 27. The heating unit may be disposed in a preceding process of the forming device 1 to perform heating externally.

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 has been brought into a high-temperature state by being heated by the heating unit 5, to expand the metal pipe material 40. The fluid supply units 6 are 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 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 where sealing performance is secured during the fluid supply and exhaust, and causes the nozzle 31 to be spaced apart 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. Additionally, the fluid supply unit 6 may include the heating unit 5 together with the holding unit 4 including a mechanism that moves the metal pipe material 40 in the up-down direction as the same device.

Components of the holding unit 4, the heating unit 5, and the fluid supply unit 6 may be configured as a unitized heating and expanding unit 150. FIG. 2A is a schematic side view illustrating the heating and expanding unit 150. FIG. 2B is a sectional view illustrating a state where the nozzle 31 has sealed the metal pipe material 40.

As illustrated in FIG. 2A, the heating and expanding unit 150 includes the lower electrode 26, the upper electrode 27, an electrode mounting unit 151 in which the electrodes 26 and 27 are mounted, the nozzle 31, the drive mechanism 32, an elevating unit 152, and a unit base 153. The electrode mounting unit 151 includes an elevating frame 154 and electrode frames 156 and 157. The electrode frames 156 and 157 function as a part of a drive mechanism 60 that supports and moves each of the electrodes 26 and 27. The drive mechanism 32 drives the nozzle 31 and moves up and down together with the electrode mounting unit 151. The drive mechanism 32 includes a piston 61 that holds the nozzle 31, and a cylinder 62 that drives the piston. The elevating unit 152 includes an elevating frame base 64 attached to an upper surface of the unit base 153, and an elevating actuator 66 that applies an elevating operation to the elevating frame 154 of the electrode mounting unit 151 by using the elevating frame base 64. The elevating frame base 64 includes guide portions 64a and 64b that guide the elevating operation of the elevating frame 154 with respect to the unit base 153. The elevating unit 152 functions as a part of the drive mechanism 60 of the holding unit 4. The heating and expanding unit 150 includes a plurality of the unit bases 153 of which the upper surfaces have different inclination angles, and is allowed to collectively change and adjust inclination angles of the lower electrode 26, the upper electrode 27, the nozzle 31, the electrode mounting unit 151, the drive mechanism 32, and the elevating unit 152 by replacing the unit bases 153.

The nozzle 31 is a cylindrical member into which the end portion of the metal pipe material 40 can be inserted. The nozzle 31 is supported by the drive mechanism 32 such that a center line of the nozzle 31 coincides with a reference line SL1. An inner diameter of a supply port 31a at an end portion of the nozzle 31 on the metal pipe material 40 side substantially coincides with an outer diameter of the metal pipe material 40 after expansion forming. In this state, the nozzle 31 supplies the high-pressure fluid from an internal flow path 63 to the metal pipe material 40. Examples of the high-pressure fluid include a gas.

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 and causes the cooling water to circulate through the flow paths 36.

The control unit 8 is a device that controls the entire forming device 1. The control unit 8 controls the drive mechanism 3, the holding unit 4, the heating unit 5, the fluid supply unit 6, and the cooling unit 7. The control unit 8 repeatedly performs the operation of forming the metal pipe material 40 using the forming die 2.

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 such 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. In addition, the control unit 8 controls the heating unit 5 to electrically heat the metal pipe material 40. Therefore, an axial current flows through the metal pipe material 40, and an electric resistance of the metal pipe material 40 itself causes the metal pipe material 40 itself to generate heat due to Joule heat.

The control unit 8 controls 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, thereby closing the forming die 2. 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. Therefore, the metal pipe material 40 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 where 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.

The metal pipe 41 after forming will be described with reference to FIG. 3B. FIG. 3B is a schematic sectional view illustrating a state immediately after the metal pipe 41 is formed by the forming die 2. The metal pipe 41 includes a pipe portion 42 and a pair of flange portions 43. The pipe portion 42 has a rectangular shape in a cross-sectional view. The pipe portion 42 includes four corner portions 44A, 44B, 44C, and 44D. The corner portions 44A, 44B, 44C, and 44D have an R-shape curved to protrude to the outer peripheral side. The pair of flange portions 43 protrude in the width direction from the side wall portions on both sides of the pipe portion 42 to the outer peripheral side, respectively.

The forming die 2 will be described in detail with reference to FIG. 3A. FIG. 3A is a schematic sectional view illustrating the forming die 2 in an initial forming state. The forming die 2 has the main dies 11 and 12 that face each other in the up-down direction (first direction), and double-action dies 18A and 18B movable relative to the main dies 11 and 12. The double-action dies 18A and 18B are movable in the width direction that is a direction intersecting the up-down direction in a cross-sectional view. The double-action die 18A is disposed on one side in the width direction with respect to the main dies 11 and 12. The double-action die 18B is disposed on the other side in the width direction with respect to the main dies 11 and 12. The double-action dies 18A and 18B are disposed at a position between the main die 11 and the main die 12 in the up-down direction.

The main dies 11 and 12 have a pipe portion forming surface 81 for forming the pipe portion 42 and a flange portion forming surface 82 for forming the flange portion 43. The main die 12 has a corner portion forming surface 83A for forming the corner portion 44A, and a corner portion forming surface 83B for forming the corner portion 44B. The main die 11 has a corner portion forming surface 83C for forming the corner portion 44C, and a corner portion forming surface 83D for forming the corner portion 44D. The corner portion forming surfaces 83A, 83B, 83C, and 83D have an R-shape that is curved to be recessed in a cross-sectional view.

In the initial forming state, the metal pipe material 40 is disposed between the main dies 11 and 12 in the up-down direction and between the double-action dies 18A and 18B in the width direction. The metal pipe material 40 is a metal material of an aluminum alloy. A plate thickness of the metal pipe material 40 is set to about 1.0 to 5.0 mm in order to secure sufficient strength. A radius of curvature of the R-shape of the corner portion forming surface 83 (that is, the corner portion 44) is set to be about 8.0 to 15.0 mm.

Next, an operation of the forming device 1 during the forming will be described with reference to FIGS. 4A to 4F and 5. FIGS. 4A to 4F illustrate a state of the forming die 2 at each timing. In FIGS. 4A to 4F, an arrow attached to each die indicates an operation (or an operation in progress) of the die in a next step. FIG. 5 is a graph illustrating temporal changes in the positions of the main dies 11 and 12, the positions of the double-action dies 18A and 18B, and a pressure of air blow to the metal pipe material 40.

FIG. 4A illustrates an initial state, which is a state where the operations of the main dies 11 and 12 are started (timing T1a in FIG. 5). FIG. 4B illustrates a state where the main dies 11 and 12 are disposed at a primary blow forming position, which is a state before insertion of the double-action dies 18A and 18B and before primary blow is performed (timing T1b in FIG. 5). In this state, the metal pipe material 40 is in a state of not being deformed and is in contact with (or close to) the main dies 11 and 12. In the metal pipe material 40, the portions corresponding to the corner portions 44A, 44B, 44C, and 44D will be referred to as corner portion corresponding parts 46A, 46B, 46C, and 46D. The corner portion corresponding parts 46A, 46B, 46C, and 46D are parts that become the corner portions 44A, 44B, 44C, and 44D after forming. At the timing T1b, the corner portion corresponding parts 46A, 46B, 46C, and 46D are in a state of being separated from the corner portion forming surfaces 83A, 83B, 83C, and 83D. Then, the double-action dies 18A and 18B are inserted. In addition, after the double-action dies 18A and 18B are inserted, the primary blow is performed.

FIG. 4C illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state after the double-action dies 18A and 18B are inserted and after the primary blow is performed (timing T1c in FIG. 5). In this state, both end portions of the metal pipe material 40 in the width direction are pushed to the center side in the width direction by the double-action dies 18A and 18B. In this case, the corner portion corresponding parts 46A, 46B, 46C, and 46D are bent to be protrude to the outer peripheral side by bending processing. As a result, the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed to the positions close to the corner portion forming surfaces 83A, 83B, 83C, and 83D. That is, the forming device 1 presses the metal pipe material 40 by the double-action dies 18A and 18B such that the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed against the corner portion forming surfaces 83A, 83B, 83C, and 83D. In addition, by the primary blow, the corner portion corresponding parts 46A, 46B, 46C, and 46D are further brought closer to the corner portion forming surfaces 83A, 83B, 83C, and 83D. Then, the double-action dies 18A and 18B move to a retreat position. The double-action die insertion operation and the primary blow pressurization may be performed individually or simultaneously. In a case of the individual operation, either one may be performed first.

FIG. 4D illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state after the double-action dies 18A and 18B are retreated to the retreat position and after the primary blow is performed (timing T1d in FIG. 5). Then, the main dies 11 and 12 move to the mold clamping position. FIG. 4E illustrates a state where the main dies 11 and 12 are disposed at the secondary blow forming position (mold clamping position), which is a state before the secondary blow is performed (the timing T1e in FIG. 5). As a result, the pipe portion 42 and the flange portion 43 are formed. Then, the secondary blow is performed. FIG. 4F illustrates a state where the main dies 11 and 12 are disposed at the secondary blow forming position (mold clamping position), which is state after the secondary blow is performed (timing T1f in FIG. 5). The corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed to the positions close to the corner portion forming surfaces 83A, 83B, 83C, and 83D. Therefore, the corner portion corresponding parts 46A, 46B, 46C, and 46D are pressed against the corner portion forming surfaces 83A, 83B, 83C, and 83D by the secondary blow without relying on a large deformation resistance due to the plate thickness. As a result, the corner portions 44A, 44B, 44C, and 44D along the R-shape of the corner portion forming surfaces 83A, 83B, 83C, and 83D are formed, and the metal pipe 41 is completed.

Next, the operations and effects of the forming device 1 according to the present embodiment will be described.

First, since the strength of aluminum is lower than that of steel, it is required to increase the plate thickness in order to impart the strength characteristics equivalent to those of steel to the automotive part. In order to obtain sufficient strength and rigidity, it is desirable to make the dimension of a protruding-shaped portion such as a corner portion having an R-shape as small as possible. However, in the hot air blow forming in which the high-pressure air is injected to form the shape along the die, the corner portion is theoretically formed by expanding the pipe of the member, and it becomes more difficult to perform forming as the plate thickness becomes thicker. On the other hand, it is desirable to reduce the pressure to 35 MPa or less, which is, for example, a specification limit of a general-purpose compressor, for energy saving. However, in such a case, the degree of machining becomes larger in order to obtain the desired R-shape, and it becomes difficult to perform forming.

The forming device 1 includes the forming die 2 that is curved to be recessed in a cross-sectional view and that has the corner portion forming surfaces 83A, 83B, 83C, and 83D for forming the corner portions 44A, 44B, 44C, and 44D of the metal pipe 41. In a case where the plate thickness of the metal pipe 41 of the aluminum alloy is large, the deformation resistance is increased, and the corner portion corresponding parts 46A, 46B, 46C, and 46D are less likely to be deformed along the shape of the corner portion forming surface. In contrast, the forming die 2 includes the double-action dies 18A and 18B that are movable relative to the first main die and the second main die. The forming device 1 presses the metal pipe material 40 by the double-action dies 18A and 18B such that the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed against the corner portion forming surfaces 83A, 83B, 83C, and 83D. In this case, the pushed corner portion corresponding parts 46A, 46B, 46C, and 46D are bent into shapes along the corner portion forming surfaces 83A, 83B, 83C, and 83D. In this state, the corner portion corresponding parts 46A, 46B, 46C, and 46D are easily deformed into a shape along the corner portion forming surfaces 83A, 83B, 83C, and 83D even when the deformation resistance is large. As a result, the corner portions 44A, 44B, 44C, and 44D of the metal pipe 41 of the aluminum alloy after forming can be formed into a desired shape.

The double-action dies 18A and 18B may push the corner portion corresponding parts 46A, 46B, 46C, and 46D against the corner portion forming surfaces 83A, 83B, 83C, and 83D in a stage before the main dies 11 and 12 move to the mold clamping position. In this case, the corner portion corresponding parts 46A, 46B, 46C, and 46D can be brought closer to the corner portion forming surfaces 83A, 83B, 83C, and 83D in a stage before the metal pipe 41 is completed by moving the main dies 11 and 12 to the mold clamping position. Therefore, at the time of completion of the metal pipe 41, the corner portions 44A, 44B, 44C, and 44D having a shape along the corner portion forming surfaces 83A, 83B, 83C, and 83D are easily formed.

The double-action dies 18A and 18B are movable in the width direction in a cross-sectional view, and the double-action dies 18A and 18B may press a part different from the corner portion corresponding parts 46A, 46B, 46C, and 46D in the metal pipe material 40. In this case, the double-action dies 18A and 18B press the metal pipe material 40 in the width direction, so that the portion of the metal pipe material 40 near the corner portion corresponding parts 46A, 46B, 46C, and 46D is pushed out to the main die 11 and 12 sides. As a result, the corner portion corresponding parts 46A, 46B, 46C, and 46D are bent to be pushed against the corner portion forming surfaces 83A, 83B, 83C, and 83D.

FIG. 11 is a relationship between the plate thickness and the forming limit of the corner portion when the aluminum alloy pipe is STAF-formed under the forming conditions of a heating temperature of 450° C. and an air blow pressure of 35 MPa. A higher heating temperature is desirable in view of formability, but the upper limit is about 450° C. in view of a melting point of the aluminum alloy. Therefore, when the formability under the conditions of 450° C. and 35 MPa is confirmed, a relationship of “y=7.11e{circumflex over ( )}0.145x” is satisfied between a formable limit (y) of the corner portion and the plate thickness (x).

The present disclosure is not limited to the above-described embodiment.

The configuration of the double-action die is not limited to the above-described embodiment. For example, the forming die 2 according to the modification example will be described in detail with reference to FIG. 6A. The forming die 2 includes the main dies 11 and 12 and the double-action dies 19A, 19B, 19C, and 19D that are movable relative to the main dies 11 and 12. The double-action dies 19A and 19C are disposed on one side in the width direction with respect to the main dies 11 and 12. The double-action dies 19B and 19D are disposed on the other side in the width direction with respect to the main dies 11 and 12. The double-action dies 19A and 19B are disposed on the upper side. The double-action dies 19C and 19D are disposed on the lower side.

The main dies 11 and 12 have the pipe portion forming surface 81. The double-action dies 19A, 19B, 19C, and 19D is provided with the flange portion forming surface 82. The double-action die 19A has the corner portion forming surface 83A. The double-action die 19B has the corner portion forming surface 83B. The double-action die 19C has the corner portion forming surface 83C. The double-action die 19D has the corner portion forming surface 83D.

Next, an operation of the forming device 1 during forming will be described with reference to FIGS. 6A to 6F and 7. FIGS. 6A to 6F illustrate a state of the forming die 2 at each timing. FIG. 7 is a graph illustrating temporal changes in the positions of the main dies 11 and 12, the positions of the double-action dies 19A, 19B, 19C, and 19D, and the pressure of the air blow to the metal pipe material 40.

FIG. 6A illustrates an initial state, which is a state where the operations of the main dies 11 and 12 are started (timing T2a in FIG. 7). FIG. 6B illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state before the double-action dies 19A, 19B, 19C, and 19D start moving in the width direction (timing T2b in FIG. 7). In this state, the metal pipe material 40 is in a state of not being deformed and is in contact with (or close to) the main dies 11 and 12. At the timing T2b, the corner portion corresponding parts 46A, 46B, 46C, and 46D are in a state of being separated from the corner portion forming surfaces 83A, 83B, 83C, and 83D. Then, the double-action dies 19A, 19B, 19C, and 19D move in the width direction. In addition, after the double-action dies 19A, 19B, 19C, and 19D move, the primary blow is performed.

FIG. 6C illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state after the double-action dies 19A, 19B, 19C, and 19D are disposed at the insertion position by moving in the width direction and before the primary blow is performed (timing T2c in FIG. 7). In this state, the double-action dies 19A, 19B, 19C, and 19D are pressed against the corner portion corresponding parts 46A, 46B, 46C, and 46D of the metal pipe material 40. In this case, the corner portion corresponding parts 46A, 46B, 46C, and 46D are bent to be protrude to the outer peripheral side by bending processing. As a result, the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed to the positions close to the corner portion forming surfaces 83A, 83B, 83C, and 83D. That is, the forming device 1 presses the metal pipe material 40 by the double-action dies 19A, 19B, 19C, and 19D such that the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed against the corner portion forming surfaces 83A, 83B, 83C, and 83D.

FIG. 6D illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, and the double-action dies 19A, 19B, 19C, and 19D are disposed at the insertion position, which is a state after the primary blow is performed (timing T2d in FIG. 7). By the primary blow, the corner portion corresponding parts 46A, 46B, 46C, and 46D are further brought closer to the corner portion forming surfaces 83A, 83B, 83C, and 83D. Then, the main dies 11 and 12 and the double-action dies 19A, 19B, 19C, and 19D move to the mold clamping position. FIG. 6E illustrates a state where the main dies 11 and 12 and the double-action dies 19A, 19B, 19C, and 19D are disposed at the secondary blow forming position (mold clamping position), which is a state before the secondary blow (timing T2e in FIG. 7). As a result, the pipe portion 42 and the flange portion 43 are formed. Then, the secondary blow is performed. FIG. 6F illustrates a state where the main dies 11 and 12 and the double-action dies 19A, 19B, 19C, and 19D are disposed at the secondary blow forming position (mold clamping position), which is after the secondary blow is performed (timing T2f in FIG. 7). As a result, the corner portions 44A, 44B, 44C, and 44D along the R-shape of the corner portion forming surfaces 83A, 83B, 83C, and 83D are formed, and the metal pipe 41 is completed.

As described above, the double-action dies 19A, 19B, 19C, and 19D have the corner portion forming surfaces 83A, 83B, 83C, and 83D, and the corner portion forming surfaces 83A, 83B, 83C, and 83D may be pressed against the corner portion corresponding parts 46A, 46B, 46C, and 46D. In this case, the vicinity of the corner portion corresponding parts 46A, 46B, 46C, and 46D of the metal pipe material 40 is bent to have a shape along the corner portion forming surfaces 83A, 83B, 83C, and 83D of the double-action dies 19A, 19B, 19C, and 19D.

The forming die 2 according to another modification example will be described in detail with reference to FIG. 8A. The forming die 2 includes the main dies 11 and 12, the double-action dies 18A and 18B, and the double-action dies 19A, 19B, 19C, and 19D. An operation of the forming device 1 during forming will be described with reference to FIGS. 8A to 8C and 9. FIGS. 8A to 8C illustrate a state of the forming die 2 at each timing. FIG. 9 is a graph illustrating temporal changes in the positions of the main dies 11 and 12, the positions of the double-action dies 18A and 18B, the positions of the double-action dies 19A, 19B, 19C, and 19D, and the pressure of the air blow to the metal pipe material 40.

FIG. 8A illustrates an initial state, which is a state where the operations of the main dies 11 and 12 are started (timing T3a in FIG. 9). FIG. 8B illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state before the double-action dies 18A, 18B, 19A, 19B, 19C, and 19D start moving in the width direction (timing T3b in FIG. 9). In this state, the metal pipe material 40 is in a state of not being deformed and is in contact with (or close to) the main dies 11 and 12. At the timing T3b, the corner portion corresponding parts 46A, 46B, 46C, and 46D are in a state of being separated from the corner portion forming surfaces 83A, 83B, 83C, and 83D. Then, the double-action dies 18A, 18B, 19A, 19B, 19C, and 19D move in the width direction. In addition, after the double-action dies 18A, 18B, 19A, 19B, 19C, and 19D move, the primary blow is performed.

FIG. 8C illustrates a state where the main dies 11 and 12 are disposed at the primary blow forming position, which is a state after the double-action dies 18A, 18B, 19A, 19B, 19C, and 19D are disposed at the insertion position by moving in the width direction and before the primary blow is performed (timing T3c in FIG. 9). In this state, the double-action dies 19A, 19B, 19C, and 19D are pressed against the corner portion corresponding parts 46A, 46B, 46C, and 46D of the metal pipe material 40. Further, both end portions of the metal pipe material 40 in the width direction are pushed to the center side in the width direction by the double-action dies 18A and 18B. In this case, the corner portion corresponding parts 46A, 46B, 46C, and 46D are bent to be protrude to the outer peripheral side by bending processing. As a result, the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed to the positions close to the corner portion forming surfaces 83A, 83B, 83C, and 83D. That is, the forming device 1 presses the metal pipe material 40 by the double-action dies 18A, 18B, 19A, 19B, 19C, and 19D such that the corner portion corresponding parts 46A, 46B, 46C, and 46D are pushed against the corner portion forming surfaces 83A, 83B, 83C, and 83D. In addition, the double-action dies 18A and 18B are retreated to the retreat position, but the subsequent operations are the same as those in FIGS. 6C to 6F.

As illustrated in FIG. 10, the double-action dies 19A and 19B may be provided on the upper side, and only the main die 11 may be provided on the lower side without providing the double-action dies 19C and 19D.

The forming device need only be a forming device that forms a metal material of an aluminum alloy, and a forming device using a hot stamping method, a hydroforming method, or the like may be adopted.

In the above-described embodiment, the metal pipe includes the flange portion, but need not have the flange portion. In addition, the metal material need not be a pipe, and may be a plate material.

Aspect 1

A forming device that forms a metal member from a metal material of an aluminum alloy, the forming device including: a forming die that is curved to be recessed in a cross-sectional view and that includes a corner portion forming surface for forming a corner portion of the metal member, in which the forming die includes a first main die and a second main die that face each other, and a double-action die that is movable relative to the first main die and the second main die, and the metal material is pressed by the double-action die such that a corner portion corresponding part corresponding to the corner portion in the metal material is pushed against the corner portion forming surface.

Aspect 2

The forming device according to Aspect 1, in which the double-action die pushes the corner portion corresponding part against the corner portion forming surface in a stage before the first main die and the second main die move to a mold clamping position.

Aspect 3

The forming device according to Aspect 1 or 2, in which the double-action die is movable in a second direction intersecting a first direction in which the first main die and the second main die face each other in a cross-sectional view, and the double-action die presses a part different from the corner portion corresponding part in the metal material.

Aspect 4

The forming device according to any one of Aspects 1 to 3, in which the double-action die includes the corner portion forming surface, and presses the corner portion forming surface against the corner portion corresponding part.

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.

Claims

1. A forming device that forms a metal member from a metal material of an aluminum alloy, the forming device comprising: a forming die that is curved to be recessed in a cross-sectional view and that includes a corner portion forming surface for forming a corner portion of the metal member,wherein the forming die includes a first main die and a second main die that face each other, anda double-action die that is movable relative to the first main die and the second main die, andthe metal material is pressed by the double-action die such that a corner portion corresponding part corresponding to the corner portion in the metal material is pushed against the corner portion forming surface.

2. The forming device according to claim 1, further comprising: a drive mechanism configured to move at least one of the first main die and the second main die;a holding unit configured to hold the metal material disposed between the first main die and the second main die;a heating unit configured to heat the metal material by energizing the metal material;a fluid supply unit configured to supply a fluid having a high pressure into the metal material held between the first main die and the second main die;a cooling unit configured to cool the forming die; anda control unit configured to control the drive mechanism, the holding unit, the heating unit, the fluid supply unit, the cooling unit.

3. The forming device according to claim 2, wherein the drive mechanism includes a slide configured to move the second main die such that the first main die and the second main die are joined together,a pull-back cylinder configured to generate a force for pulling the slide upward,a main cylinder configured to apply downward pressure to the slide, anda drive source configured to apply a driving force to the main cylinder.

4. The forming device according to claim 2, wherein the holding unit includes a lower electrode and an upper electrode configured to hold the metal material by interposing vicinities of end portions of the metal material from an up-down direction in a longitudinal direction of the forming die.

5. The forming device according to claim 4, wherein the lower electrode and the upper electrode are configured to move independently of each other in the up-down direction.

6. The forming device according to claim 2, wherein the heating unit includes a lower electrode and an upper electrode in a longitudinal direction of the forming die, anda power supply configured to cause a current to flow through the metal material via the lower electrode and the upper electrode.

7. The forming device according to claim 2, wherein the fluid supply unit includes a nozzle configured to supply the fluid from an opening portion of an end portion of the metal material to an inside of the metal material,a drive mechanism configured to move the nozzle forward and backward with respect to the opening portion of the metal material, anda supply source configured to supply the fluid having a high-pressure into the metal material via the nozzle.

8. The forming device according to claim 2, wherein the cooling unit includes flow paths formed inside the first main die and the second main die, anda water circulation mechanism configured to supply a cooling water to the flow paths and cause the cooling water to circulate through the flow paths.

9. The forming device according to claim 1, wherein the double-action die pushes the corner portion corresponding part against the corner portion forming surface in a stage before the first main die and the second main die move to a mold clamping position.

10. The forming device according to claim 1, wherein the double-action die is movable in a second direction intersecting a first direction in which the first main die and the second main die face each other in a cross-sectional view, andthe double-action die presses a part different from the corner portion corresponding part in the metal material.

11. The forming device according to claim 1, wherein the double-action die includes the corner portion forming surface, and presses the corner portion forming surface against the corner portion corresponding part.

12. The forming device according to claim 1, wherein the metal material is brought into contact with the double-action die after the metal material is brought into contact with the first main die and the second main die.