Press forming method and press forming device

Abstract

Provided is a press forming method that can suppress springback while suppressing the complexity of processes and operations. [Solution] The present invention is a method using a press molding device Z, which includes a first bending process in which, while the top plate portion 811 is fixed with a fixing member Z1 so that the top plate portion 811 does not move during molding and while at least a portion of the outer surface of the inclined wall portion 812 is abutted against the molding side surface Z2a, the mold member Z2 is moved toward the fixing member Z1, causing the inclined wall portion 812 to protrude toward the molding side surface Z2a and deforming the inclined wall portion 812 to fit along the molding side surface Z2a; and a second bending process in which, while maintaining the state of the first bending process, the tip surface 812b of the inclined wall portion 812 abuts against a part of the press molding device Z, applying a compressive force to the tip surface 812b in a direction that reduces the plate length of the inclined wall portion 812, and bending the inclined wall portion 812 into a shape that fits along the molding side surface Z2a.

Description

[Technical Field]

[0001] The present invention relates to a press-forming method and a press-forming apparatus. [Background technology]

[0002] As a press forming method, for example, Japanese Patent Application Laid-Open Publication No. 2014-4618 discloses a method for manufacturing a molded product having a U-shaped cross section by bending. This press forming method includes a press bending process in which a die is lowered to bend the metal material while the metal material is pressed by a punch and a pad, and a press bending process in which the die is moved diagonally downward toward the punch after the press bending process to bend the metal material. The press bending process is performed while the width direction leading edge of the metal material is in contact with the vertical wall of the die. Furthermore, for example, Japanese Patent Application Laid-Open Publication No. 2022-39327 discloses a straightening method performed during finishing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-4618 [Patent Document 2] Japanese Patent Publication No. 2022-39327 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the former processing method does not suppress springback during bending, which is a problem in plate bending, for example. Suppression of springback during bending has long been desired in press forming, including bending. Furthermore, the above-mentioned correction method is intended for correction at the final stage of forming, and is not only complex in mechanism but is also expected to be performed separately from the bending process during forming. In other words, it is not expected that bending and correction will be performed in a single process. Furthermore, this method requires a two-step operation during correction: the pad releases the top plate portion from its fixed position, and then the pad clamps the top plate portion. In other words, many processes and operations are required overall.

[0005] An object of the present invention is to provide a press-forming method and press-forming apparatus that can suppress springback of bending while suppressing the complexity of the process and operation. [Means for solving the problem]

[0006] The press molding method of the present invention is a press molding method using a press molding device that includes a fixing member that clamps and fixes a top plate portion and a sloping wall portion that is inclined in a predetermined rotational direction relative to the top plate portion, and a mold member that has a molding side surface formed to match the target shape of the sloping wall portion.The press molding method includes a first bending process in which, while the top plate portion is fixed by the fixing member so that it does not move during molding, and while at least a portion of the outer surface of the sloping wall portion is abutted against the molding side surface, the mold member is moved toward the fixing member, causing the sloping wall portion to protrude toward the molding side surface and deforming the sloping wall portion along the molding side surface; and a second bending process in which, while maintaining the state of the first bending process, a compressive force, which is a force in a direction that reduces the plate length of the sloping wall portion, is applied to the tip surface of the tip surface by abutting the tip surface of the sloping wall portion against a part of the press molding device, and the sloping wall portion is bent into a shape that matches the molding side surface.

[0007] A press forming apparatus according to a first aspect of the present invention is a press forming apparatus for press-forming a preform having a top plate portion and an inclined wall portion inclined in a predetermined rotational direction relative to the top plate portion, and includes a fixed member configured to be able to clamp and fix the top plate portion between one member and another member, a mold member having a forming side surface formed to match the target shapes of the first inclined wall portion and the second inclined wall portion, and a drive device that moves the mold member toward the fixed member (common configuration). The other member has a forming recess formed to match the target shapes of the curved portions of the top plate portion and the inclined wall portion on the surface facing the one member.

[0008] In a press molding apparatus according to a second aspect of the present invention, in a common configuration, the mold member is provided with an engaging portion that protrudes from the molding side surface and engages with the tip of the inclined wall portion so that the tip of the inclined wall portion is aligned with the molding side surface.

[0009] In a press forming apparatus according to a third aspect of the present invention, in a common configuration, one of the members has a protrusion formed thereon that protrudes toward the forming side surface so as to abut against the tip surface of the inclined wall portion during forming. [Effects of the Invention]

[0010] According to the press forming method of the present invention, in the first bending step, the inclined wall portion is pressed against the forming side surface in a protruding manner, and gradually deforms along the forming side surface as the die member moves. That is, in the first bending step, the inclined wall portion can be conformed to the forming side surface.

[0011] In the second bending process, the curved portion of the inclined wall (the portion curved from the top plate) is deformed by applying a compressive force from the tip surface of the inclined wall and a pressing force from the fixed top plate. This promotes plastic deformation of the curved portion. In the second bending process, the stress distribution in the curved portion of the inclined wall increases in the compressive stress region (inner portion of the bend) and decreases in the tensile stress region (outer portion of the bend). When this further results in compressive strain, the stress becomes compressive. This reduces the bending moment generated in the curved portion of the inclined wall, and also reduces the amount of springback.

[0012] Thus, according to the press forming method of the present invention, a press-formed product with suppressed springback can be formed by the simple operation of fixing the top plate portion and moving the die member.

[0013] According to the press-forming device of the first embodiment of the present invention, the forming recessed portion allows for improved forming accuracy of the curved portions of the top plate portion and the inclined wall portion without requiring any complex mechanism or operation.

[0014] According to the press forming apparatus of the second aspect of the present invention, the die member can be moved with the tip of the inclined wall engaged with the engaging portion. This makes it easy to deform the inclined wall so that it conforms to the forming side surface. Furthermore, by engaging with the engaging portion and moving the die member, it is also possible to bend the inclined wall while applying a compressive force to the tip surface of the inclined wall. This configuration allows for highly accurate bending without complex mechanisms or operations.

[0015] According to the press forming apparatus of the third aspect of the present invention, a protrusion is formed according to the target shape of the inclined wall portion, so that a compressive force can be applied to the tip end surface more reliably in the second bending step. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a conceptual diagram of a preform and a press molding device according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a conceptual diagram for explaining the flow of a first example of the present embodiment. [Figure 3] FIG. 10 is a conceptual diagram for explaining the flow of a second example of the present embodiment. [Figure 4] FIG. 10 is a conceptual diagram for explaining the flow of a third example of the present embodiment. [Figure 5] 1A to 1C are conceptual diagrams of a plate material, a preform, and a press-formed product according to related art. [Figure 6] 1 is a flowchart of a press forming method according to the related art. [Figure 7]FIG. 1 is a configuration diagram of a press forming apparatus (pre-bending process) according to a related art. [Figure 8] FIG. 10 is a conceptual diagram for explaining the operation of a press-forming device (pre-bending process) of the related art. [Figure 9] FIG. 10 is a conceptual diagram for explaining the operation of a press-forming device (pre-bending process) of the related art. [Figure 10] FIG. 1 is a configuration diagram of a press forming device (specific bending process) according to a related art. [Figure 11] FIG. 1 is a partially enlarged conceptual diagram of a press forming apparatus (specific bending process) according to the related art. [Figure 12] FIG. 10 is a conceptual diagram for explaining the movement of a press forming apparatus (specific bending process) of the related art. [Figure 13] FIG. 1 is a partially enlarged conceptual diagram of a press forming apparatus (specific bending process) according to the related art. [Figure 14] FIG. 10 is a conceptual diagram for explaining the movement of a press forming apparatus (specific bending process) of the related art. [Figure 15] FIG. 10 is a conceptual diagram of a modified embodiment of a press forming apparatus according to the related art. [Figure 16] FIG. 10 is a conceptual diagram of a modified embodiment of a press forming apparatus according to the related art. [Figure 17] FIG. 10 is a conceptual diagram of another example of a preform according to the related art. [Figure 18] FIG. 10 is a conceptual diagram for explaining the operation of a press-forming device (pre-bending process) of the related art. [Figure 19] FIG. 1 is a conceptual diagram for explaining the stress state of a conventional press-formed product. [Figure 20] FIG. 1 is a conceptual diagram for explaining the stress state of a press-formed product according to a related art. [Figure 21] 1A and 1B are conceptual diagrams for explaining deformation of a press-formed product according to a related art; [Figure 22] FIG. 1 is a plan view showing an example of the shape of a plate material used in the related art. [Figure 23] FIG. 1 is a conceptual diagram for explaining a related art. [Figure 24] FIG. 1 is a perspective view showing an example of a press-formed product according to a related art technique. [Figure 25] FIG. 2 is a conceptual diagram of an example of a preform according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, as a mode for carrying out the present invention, a press-forming apparatus Z and a press-forming method according to one embodiment of the present invention will be described in detail with reference to the drawings. In addition to the following examples, the present invention can be carried out in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

[0018] As shown in FIG. 1, the press forming method of this embodiment is a press forming method performed on a preformed product 81, and is a method using a press forming apparatus Z. The preformed product 81 has a top plate portion 811 and an inclined wall portion 812 inclined in a predetermined rotational direction relative to the top plate portion 811. The inclined wall portion 812 has one or more curved portions. As will be described later, the preformed product 81 is formed from a plate material through a pre-bending process using a press forming apparatus. The press forming apparatus Z has a fixing member Z1, a die member Z2, and a driving device Z3.

[0019] The fixing member Z1 is configured so that the top plate portion 811 can be sandwiched and fixed between two members. That is, the fixing member Z1 is configured with two members arranged opposite to each other. The fixing member Z1 includes a punch (corresponding to "one member") Z11 and a pad (corresponding to "the other member") Z12 arranged opposite to the punch Z11. The punch is also called a punch. In addition, in Figs. 1 to 4, the arrangement of the device (member) may be upside down. At least in Figs. 2 to 4, the left-right direction of the drawings will be described as the left-right direction.

[0020] The die member Z2 has a forming side surface Z2a formed to match the target shape of the inclined wall portion 812. The die member Z2 is arranged on the left and right of the punch Z11. The die member Z2 includes a first die Z21 arranged on one side (left side in the figure) of the punch Z11 and a second die Z22 arranged on the other side (right side in the figure) of the punch Z11. The forming side surface Z2a is formed on the side of each of the dies Z21 and Z22 facing the punch Z11. The forming side surface Z2a is curved in an arc-shaped concave shape to match the target shape of the inclined wall portion 812. For example, cam sliders 71 and 72 described below may be used as the die member Z2.

[0021] The driving device Z3 is a device that moves the mold member Z2 toward the fixed member Z1. In other words, the driving device Z3 is a device that moves each of the dies Z21 and Z22 toward the fixed member Z1 (in the direction of moving them closer to each other). The driving device Z3 of this embodiment can move the mold member Z2 in the left-right direction (in the direction of moving them closer to each other and away from each other). The driving device Z3 is equipped with, for example, an electric motor. The driving device Z3 also has the function of moving each member of the fixed member Z1 closer to each other, moving them apart, or moving them together (i.e., moving them up and down). Note that the movement of the fixed member Z1 and the movement of the mold member Z2 may be configured to be linked, for example, like the mechanism of cam sliders 71 and 72 described below.

[0022] The driving device Z3 can change the distance between the punch Z11 and the pad Z12 to fix the top plate portion 811 to the fixing member Z1. The driving device Z3 can also move the first die Z21 to the right and the second die Z22 to the left. The driving device Z3 can also move each member in a direction away from each other. The operating mechanism of the press forming apparatus Z may be the same as that of the press forming apparatus 1A described later, or may be a well-known mechanism.

[0023] In this embodiment, the die member Z2 moves relatively closer to the punch Z11 and also to the pad Z12. That is, the die member Z2 moves obliquely relative to the fixed member Z1. The drive unit Z3 may move only the die member Z2 or may move the fixed member Z1 and the die member Z2 together in the relative oblique movement. For example, the die member Z2 moves obliquely relative to the first die Z21 by moving the first die Z21 to the right, the second die Z22 to the left, and the fixed member Z1 downward.

[0024] The press forming method of this embodiment includes a first bending step and a second bending step. In the first bending step, the top plate portion 811 is fixed by the fixing member Z1 so that the top plate portion 811 does not move during forming, and at least a part of the outer surface of the inclined wall portion 812 is abutted against the forming side surface Z2a. In this state, the die member Z2 is moved toward the fixing member Z1, causing the inclined wall portion 812 to protrude toward the forming side surface Z2a and deforming the inclined wall portion 812 along the forming side surface Z2a.

[0025] The second bending process is a process in which, while maintaining the state of the first bending process (fixed and moving state), the tip end surface 812b of the inclined wall portion 812 abuts against a part of the press-forming device Z, and a compressive force, which is a force in a direction that reduces the plate length of the inclined wall portion 812, is applied to the tip end surface 812b of the inclined wall portion 812, thereby bending the inclined wall portion 812 into a shape that conforms to the forming side surface Z2a. Note that the first bending process and the second bending process may be performed simultaneously. That is, for example, while applying a compressive force to the tip end surface 812b, the inclined wall portion 812 may be caused to protrude toward the forming side surface Z2a, and the inclined wall portion 812 may be deformed to conform to the forming side surface Z2a. Each bending process is performed by operating the press-forming device Z. Pressing the preform 81 to generate a compressive force (also called an axial force) is also called "axial pressing."

[0026] According to this embodiment, in the first bending process, as the top plate portion 811 is fixed and the mold member Z2 moves, the inclined wall portion 812 is deformed while receiving pressure from the top plate portion 811 and pressure from the forming side surface Z2a. The inclined wall portion 812 protrudes and is pressed against the forming side surface Z2a, and gradually deforms along the forming side surface Z2a as the mold member Z2 moves. That is, in the first bending process, the inclined wall portion 812 can bend to the forming side surface Z2a. In the second bending process, a compressive force is applied to the tip surface 812b of the inclined wall portion 812 while maintaining the state of the first bending process (fixing the top plate portion 811 and moving the mold member Z2). The inclined wall portion 812 is deformed in a state in which the compressive force from the tip surface 812b of the inclined wall portion 812 and the pressing force from the fixed top plate portion 811 are applied to the curved portion of the inclined wall portion 812 (the portion curved from the top plate portion). This promotes plastic deformation of the curved portion.

[0027] Furthermore, in the second bending process, in the stress distribution of the bent portion (curved portion) of the inclined wall portion 812, the compressive stress in the compressive stress region (inner portion of the bend) increases, the tensile stress in the tensile stress region (outer portion of the bend) decreases, and when further compressive strain occurs, the stress becomes compressive. As a result, the bending moment generated in the bent portion of the inclined wall portion 812 decreases, and the amount of springback also decreases.

[0028] As described above, according to the press-forming method of this embodiment, the press-formed product 9 with reduced springback can be formed by the simple operation of fixing the top plate portion 811 and moving the die member Z2. Furthermore, in the second bending process, the leading end surface 812b of the inclined wall portion 812 abuts against a part of the press-forming device Z and receives a compressive force. Therefore, even if the leading end surface 812b has irregularities, the irregularities are crushed, and the leading end surface 812b is easily formed into a flat shape. In other words, according to this embodiment, the forming accuracy of the leading end surface 812b (which can also be called a flange end) is improved. It can also be said that the leading end surface 812b is normalized. Furthermore, according to this embodiment, the occurrence of hair cracks can also be suppressed. Furthermore, according to this embodiment, since the preform 81 is compressed overall, the rigidity of the press-formed product (finished product) can be expected to be improved. The method of this embodiment can also be called a closed bending process.

[0029] (First Example) As shown in FIG. 1 , the inclined wall portion 812 of the preform 81 includes a first inclined wall portion 851 inclined in a predetermined rotational direction relative to the top plate portion 811, and a second inclined wall portion 852 inclined in the predetermined rotational direction relative to the first inclined wall portion 851 on the tip side of the first inclined wall portion 851. The first inclined wall portion 851 includes a curved portion 851a on the base side (top plate portion 811 side) and a flat portion 851b extending therefrom. The curved portion 851a corresponds to a shoulder portion of the preform 81. The second inclined wall portion 852 includes a curved portion 852a on the base side (first inclined wall portion 851 side) and a flat portion 852b extending therefrom. Each flat portion 851b, 852b may be curved with a gentler curve (smaller curvature) than the corresponding curved portion 851a, 852a. Thus, the inclined wall portion 812 of this example has two curved portions 851a and 852a with relatively large curvatures.

[0030] 2(1), such a preform 81 is set in a press forming device Z, and the first bending process and the second bending process of the present embodiment are performed. In the first bending process, with a contact surface 853, which is at least a part of the outer surface of the second inclined wall portion 852, in contact with the forming side surface Z2a, a partial compressive force, which is a force in a direction that reduces the plate length of the first inclined wall portion 851, is applied to the contact surface 853, and the inclined wall portion 812 is deformed.

[0031] As shown in FIG. 2(2), as the die member Z2 moves, the contact surface 853 receives a pressing force from the forming side surface Z2a. This pressing force is divided into a force toward the base side of the inclined wall portion 812 and a force toward the tip side. As shown by the arrows in FIG. 2(2), the force toward the base side of the inclined wall portion 812 is applied along the extension direction of the first inclined wall portion 851 (flat portion 851b), resulting in a partial compressive force. That is, in the first bending step, the first inclined wall portion 851 receives axial pressure from the forming side surface Z2a. Furthermore, as the die member Z2 moves, the tip end of the second inclined wall portion 852 comes into contact with the forming side surface and slides along the forming side surface Z2a toward the punch Z11. The first bending step is performed while the die member Z2 moves, causing the tip end of the inclined wall portion 812 to move (slide) along the forming side surface Z2a. In the first bending step, the tip end of the inclined wall portion 812 moves toward the contact portion Z11a while being guided by the forming side surface Z2a.

[0032] As shown in FIG. 2(3), the first inclined wall portion 851 is subjected to axial pressure from the forming side surface Z2a and deforms along the forming side surface Z2a. Between FIG. 2(3) and (4), the leading end surface 812b of the inclined wall portion 812 (second inclined wall portion 852) abuts against the side surface (contact portion Z11a) of the punch Z11. That is, the punch Z11 has the abutment portion Z11a that abuts against the leading end surface 812b during forming. The punch Z11 has a flat surface (contact portion Z11a) that is parallel to the leading end surface 812b and abuts against the leading end surface 812b during forming. In this example, the abutment portion Z11a is the side surface of the punch Z11. In the second bending process, the leading end of the inclined wall portion 812 moves while being guided by the forming side surface Z2a in the first bending process, and as a result, the leading end surface 812b abuts against the abutment portion Z11a.

[0033] The leading end surface 812b is subjected to a compressive force due to contact with the contact portion Z11a, the movement of the die member Z2, and the fixation of the top plate portion 811. With the compressive force applied to the leading end surface 812b, the inclined wall portion 812 is bent along the forming side surface Z2a. As indicated by the arrows in FIG. 2(4), the compressive force is applied to the leading end surface 812b, and axial pressure is applied in the extension direction of the second inclined portion 852 and the extension direction of the first inclined wall portion 851, thereby promoting plastic deformation of the curved portions 851a and 852a. The plate length of the inclined wall portion 812 is shortened by the compressive force. In the second bending process, as a result of the leading end of the inclined wall portion 812 being guided and moved by the forming side surface Z2a in the first bending process, the leading end surface 812b comes into contact with the contact portion Z11a, which is part of the fixing member Z1, thereby generating a compressive force.

[0034] Even when the inclined wall portion 812 has two curved portions in this way, the press forming device Z bends the inclined wall portion 812 along the forming side surface Z2a while applying a partial compressive force to the base side (first inclined wall portion 851) of the preformed product 81 in the first bending process, and bends the inclined wall portion 812 along the forming side surface Z2a while applying a compressive force from the tip surface 812b to the inclined wall portion 812 in the second bending process. This achieves the effects of this embodiment as described above (mainly the simplification of the configuration and the suppression of springback).

[0035] In addition, in this example, the punch Z11 is not involved in forming the inclined wall portion 812 except for the contact portion Z11a. In other words, the inner surface of the inclined wall portion 812 does not come into contact with the press-forming device Z in the first bending process and the second bending process. According to this example, the product shape is formed almost punch-less (only by the dies Z21 and Z22) in forming the inclined wall portion 812. Since the inclined wall portion 812 is bent to the forming side surface Z2a by axial pressing, deep forming is possible and the accuracy of the flange surface position and the surface position as seen from the side of the final shape is improved. Furthermore, this method of bending the workpiece to the die makes it less likely that shock lines will appear and suppresses the occurrence of buckling. Furthermore, it is possible to minimize the forming load. Such punch-less forming exhibits the above-mentioned effects.

[0036] In this example, the pad Z12 has a molding recess Z12a formed to match the target shape of the top plate portion 811 and the curved portion 851a of the first inclined wall portion 851. In the first and second bending steps, the top plate portion 811 and the curved portion 851a are maintained in the molding recess Z12a. As a result, in the final stage of forming (the end of the second bending step), the curved portion 851a is pressed against the molding recess Z12a, and the curved portion 851a is deformed to fit the molding recess Z12a, i.e., to fit the target shape. Therefore, the presence of the molding recess Z12a can further improve the molding accuracy of the curved portion 851a. Note that this embodiment can be implemented even if the molding recess Z12a is not formed (for example, even if the pad Z12 is flat).

[0037] (Second Example) As shown in FIG. 3(1), the preform 81 of the second embodiment includes a top plate 811, a first inclined wall 851, and a second inclined wall 852, similar to the first embodiment. The second embodiment also performs the same first and second bending steps as the first embodiment. In the second embodiment, a protruding portion Z11a protruding from the side surface of the punch Z11 is formed. Similarly to the first embodiment, a forming recess Z12a is formed in the pad Z12.

[0038] As shown in Figure 3(2), as the mold member Z2 moves, the contact surface 853 receives a pressing force from the forming side surface Z2a. As shown by the arrow in Figure 3(2), as in the first embodiment, as the contact surface 853 is pressed, a partial compressive force is applied to the first inclined wall portion 851. The tip of the second inclined wall portion 852 is bent upward in accordance with the shape of the forming side surface Z2a (there are essentially three curved portions).

[0039] As shown in FIG. 3(3), the first inclined wall portion 851 is subjected to axial pressure from the forming side surface Z2a and deforms along the forming side surface Z2a. Guided by the forming side surface Z2a, the tip end surface 812b of the inclined wall portion 812 (second inclined wall portion 852) abuts against the protruding portion (contact portion) Z11a of the punch Z11. The punch Z11 has a flat surface (part of the protruding portion: abutting portion Z11a) that is parallel to the tip end surface 812b and abuts against the tip end surface 812b during forming. In this example, the abutting portion is one of the vertical surfaces of the protruding portion Z11a (the lower surface in the drawing).

[0040] The tip surface 812b is subjected to a compressive force due to contact with the protrusion Z11a, movement of the die member Z2, and fixation of the top plate portion 811. With the compressive force applied to the tip surface 812b, the inclined wall portion 812 is bent along the forming side surface Z2a. As shown by the arrows in FIG. 3(4), the application of the compressive force to the tip surface 812b causes axial pressing corresponding to the three curved portions, promoting plastic deformation of each curved portion. The plate length of the inclined wall portion 812 is shortened by the compressive force. This also produces the same effect as in the first embodiment. In the second embodiment, the inner surface of the inclined wall portion 812 does not come into contact with the member, and forming is performed almost without punching.

[0041] (Third Example) As shown in Figure 4(1), the preform 81 of the third embodiment has a top plate portion 811 and an inclined wall portion 812 having one curved portion (shoulder portion) on each side. The mold member Z2 has an engaging portion Z2b that protrudes from the forming side surface Z2a and engages with the tip of the inclined wall portion 812 so that the tip of the inclined wall portion 812 fits along the forming side surface Z2a. The engaging portion Z2b forms a groove (recess) together with the forming side surface Z2a.

[0042] The tip of the inclined wall portion 812 fits into a groove formed by the engaging portion Z2b and the forming side surface Z2a in the first bending process and the second bending process. This keeps the tip of the inclined wall portion 812 aligned with the forming side surface Z2a even when the mold member Z2 moves. In other words, the tip of the inclined wall portion 812 does not move away from the forming side surface Z2a. The engaging portion Z2b can be considered a restricting portion that restricts movement of the tip of the inclined wall portion 812 so that the tip of the inclined wall portion 812 does not move away from the forming side surface Z2a, or a catch portion that catches on the tip of the inclined wall portion 812.

[0043] As shown in (1) and (2) of FIG. 4, in the first bending process and the second bending process, the tip of the inclined wall portion 812 remains engaged with the engaging portion Z2b. In the first bending process, as the mold member Z2 moves, the inclined wall portion 812 protrudes as it is pressed against the forming side surface Z2a and is bent along the forming side surface Z2a. The engaging portion Z2b prevents the tip of the inclined wall portion 812 from moving in response to the protrusion and bending. The engaging portion Z2b restricts the movement of the tip of the inclined wall portion 812 in a direction away from the forming side surface Z2a.

[0044] At least in the second bending step, a compressive force is generated by the contact between the engaging portion Z2b and the leading end surface 812b of the inclined wall portion 812. That is, the leading end surface 812b of the inclined wall portion 812 contacts the bottom surface of the engaging portion Z2b, and is axially pressed by the movement of the mold member Z2, thereby receiving a compressive force. The inclined wall portion 812 is bent along the forming side surface Z2a while receiving the compressive force. This achieves the same effects as the present embodiment and the above examples.

[0045] As shown in FIG. 4(1), the tip end surface 812b of the inclined wall portion 812 may be in contact with the engaging portion Z2b from the start of forming (first bending step). In this case, a compressive force is applied to the tip end surface 812b from the beginning of forming. That is, in this case, the first bending step and the second bending step are performed simultaneously. This allows the present method to be performed more efficiently and effectively. Note that, although the tip end of the inclined wall portion 812 is engaged with the engaging portion Z2b at the beginning of forming, the tip end surface 812b does not have to be in contact with the engaging portion Z2b. Even in this case, it is sufficient that the tip end of the inclined wall portion 812 slides along the forming side surface Z2a (is guided and moves deeper into the groove) during forming, and the tip end surface 812b comes into contact with the engaging portion Z2b.

[0046] Also in the third embodiment, the pad Z12 may have a molding recess Z12a formed therein. In this case, as in the above-described embodiments, the curved portions of the top plate portion 811 and the inclined wall portion 812 are accommodated in the molding recess Z12a in the first bending step and the second bending step, thereby improving the molding accuracy.

[0047] In the third example, too, in the first and second bending processes, the inner surface of the inclined wall portion 812, excluding the tip portion, does not come into contact with the press-forming device Z. In other words, the inclined wall portion 812 is formed only by the die member Z2 (each die). This achieves the same effects as in the first example. In this embodiment, the inclined wall portion 812 may be curved entirely, as shown in FIG. 25 . The inclined wall portion 812 may be curved, for example, with the same curvature. This embodiment can also be applied to a preformed product 81 having such an inclined wall portion 812. In addition, in the methods of each example, the inclined wall portion 812 is formed by conforming it to the forming side surface Z2a (by protruding and gradually deforming it into the shape of the forming side surface Z2a), so the inclined wall portion 812 is not sandwiched between the punch Z11 and the dies Z21 and Z22 in the final stage. In other words, punchless forming prevents the inclined wall portion 812 from being "pushed" in the final stage. As a result, in each embodiment, the punchless effect of the first embodiment can be achieved.

[0048] (Summary of this embodiment) The press-forming method of this embodiment is a press-forming method using a press-forming device Z including a fixing member Z1 that clamps and fixes the top plate portion 811 to a preform 81 that includes a top plate portion 811 and an inclined wall portion 812 inclined in a predetermined rotational direction relative to the top plate portion 811, and a mold member Z2 that has a forming side surface Z2a formed to match the target shape of the inclined wall portion 812. The press-forming method includes a first bending step and a second bending step. The first bending step is a step in which, in a fixed state in which the top plate portion 811 is fixed by the fixing member Z1 so that the top plate portion 811 does not move during forming and in a state in which at least a portion of the outer surface of the inclined wall portion 812 abuts against the forming side surface Z2a, the mold member Z2 is moved toward the fixing member Z1, causing the inclined wall portion 812 to protrude toward the forming side surface Z2a and deforming the inclined wall portion 812 to conform to the forming side surface Z2a. The second bending process is a process in which, while maintaining the state of the first bending process, the tip surface 812b of the inclined wall portion 812 abuts against a part of the press forming device Z, thereby applying a compressive force to the tip surface 812b in a direction that reduces the plate length of the inclined wall portion 812, and bending the inclined wall portion 812 into a shape that follows the forming side surface Z2a.

[0049] The inclined wall portion 812 may include a first inclined wall portion 851 inclined in a predetermined rotational direction relative to the top plate portion 811, and a second inclined portion 852 inclined in the predetermined rotational direction relative to the first inclined wall portion 851 on the tip side of the first inclined wall portion 851. In this case, in the first bending process, a contact surface 853, which is at least a part of the outer surface of the second inclined wall portion 852, is in contact with the forming side surface Z2a, and a partial compressive force, which is a force in a direction that reduces the plate length of the first inclined wall portion 851, is applied to the contact surface 853 to deform the inclined wall portion 812. In the second bending process, as a result of the tip portion of the inclined wall portion 812 being guided and moved by the forming side surface Z2a in the first bending process, the tip surface 812b comes into contact with the contact region Z11a, which is a part of the fixing member Z1, thereby generating a compressive force.

[0050] The fixing member Z1 may include a punch (one member) Z11 having a contact portion Z11a and a pad (other member) Z12 disposed opposite the punch Z11. In this case, the pad Z12 may have a forming recess Z12a formed to match the target shapes of the top plate portion 811 and the curved portion (connection portion with the top plate portion 811) of the inclined wall portion 812. In this case, in the first bending step and the second bending step, the top plate portion 811 and the curved portion are maintained in a state of being accommodated in the forming recess Z12a.

[0051] The fixing member Z1 may have a protrusion Z11a protruding from the forming side surface Z2a. In this case, in the second bending process, the tip end surface 812b and the protrusion Z11a come into contact with each other so that the tip end surface 812b receives a compressive force from the protrusion Z11a. In the first bending process and the second bending process, the inner surface of the inclined wall portion 812 may be designed not to come into contact with the press forming device Z.

[0052] The mold member Z2 may have an engaging portion Z2b that protrudes from the forming side surface Z2a and engages with the tip of the inclined wall portion 812 so that the tip of the inclined wall portion 812 is aligned with the forming side surface Z2a. In this case, the tip of the inclined wall portion 812 is maintained engaged with the engaging portion Z2b in the first bending process and the second bending process. In this case, a compressive force is generated at least in the second bending process due to the abutment of the engaging portion Z2b with the tip surface 812b of the inclined wall portion 812. In both the first bending process and the second bending process, the tip surface 812b may be maintained in abutment with the engaging portion Z2b. In this case, the first bending process and the second bending process are performed simultaneously. In the first bending process and the second bending process, the inner surface of the inclined wall portion 812, excluding the tip, may be designed not to abut with the press forming device Z.

[0053] The press-forming apparatus Z of the first embodiment is an apparatus for performing press-forming on a preform 81 having a top plate portion 811 and an inclined wall portion 812. This press-forming apparatus Z includes a fixing member Z1 configured to sandwich and fix the top plate portion 811 between a punch Z11 and a pad Z12, a mold member Z2 having a forming side surface Z2a formed to match the target shapes of the first inclined wall portion 851 and the second inclined wall portion 852, and a drive unit Z3 that moves the mold member Z2 toward the fixing member Z1 relative to the fixing member Z1 (common configuration). The pad Z12 of the first embodiment has a forming recess Z12a formed to match the target shapes of the top plate portion 811 and the curved portion 851a of the first inclined wall portion 851 on the surface facing the punch Z11.

[0054] The press-forming apparatus Z of the second form of this embodiment has the same configuration as the common configuration of the first form, and is an apparatus that performs press-forming on a preformed product 81 that has a top plate portion 811 and an inclined wall portion 812. The mold member Z2 of the second form has an engaging portion Z2b that protrudes from the forming side surface Z2a and engages with the tip end of the inclined wall portion 812 so that the tip end of the inclined wall portion 812 is aligned with the forming side surface Z2a.

[0055] The press-forming apparatus Z of the third embodiment has the same configuration as the first embodiment, and is an apparatus for performing press-forming on a preform 81 having a top plate portion 811 and an inclined wall portion 812. The punch Z11 of the third embodiment is formed with a protrusion Z11a that protrudes toward the forming side surface Z2a so that a tip end surface 812b abuts against the protrusion Z11a during forming. The configurations of the above embodiments are effective regardless of the number of curved portions of the inclined wall portion 812.

[0056] (Related Technology) The press-forming method of the present disclosure is a method for forming a press-formed product 9 from a plate material 80 via a preformed product 81 using a press-forming apparatus, as shown in FIG. 5 . The plate material 80 can also be considered a plate-shaped metal material or workpiece. The preformed product 81 includes a top plate portion 811 and an inclined wall portion 812 inclined in a predetermined rotation direction relative to the top plate portion 811. The inclined wall portion 812 can also be considered a portion that curves and continues from the top plate portion 811. When viewed along the rotation axis of the predetermined rotation direction (i.e., the perspective of FIG. 5 ), the inclined wall portion 812 includes a curved portion (also referred to as a “bent portion”) and a straight portion. The “plate length of the inclined wall portion 812” corresponds to the length of the inclined wall portion 812 from the top plate portion 811 to the tip surface 812b of the inclined wall portion 812, as shown in FIG. 5 . The plate length of the inclined wall portion 812 can also be said to be the longitudinal length of the inclined wall portion 812 from the perspective of viewing along the rotation axis in the predetermined rotation direction (the perspective of Figure 5). The preformed product 81 can also be said to be an intermediate formed product. The press-formed product 9 has a top plate portion 811, a shoulder R portion 92 curved from the top plate portion 811, and a vertical wall portion 93 continuing from the top plate portion 811 via the shoulder R portion 92. Note that the top plate portion of the preformed product 81 and the top plate portion of the press-formed product 9 are parts in the same position, and therefore will be referred to as the "top plate portion 811" in the description.

[0057] The angle (obtuse angle) formed between the top plate portion 811 and the inclined wall portion 812 is larger than the angle (e.g., 90 degrees) formed between the top plate portion 811 and the vertical wall portion 93. In other words, the bending angle (acute angle) of the inclined wall portion 812 relative to the top plate portion 811 is smaller than the bending angle (e.g., 90 degrees) of the vertical wall portion 93 relative to the top plate portion 811. As described above, in the press-forming method of the present disclosure, the press-forming apparatus preliminarily bends the plate material 80 to form a preformed product 81, and further performs special bending (a specific bending process described later) on the preformed product 81 to form a press-formed product 9. As shown in FIG. 6 , the press-forming method of the present disclosure includes a pre-bending process S1 and a specific bending process S2.

[0058] (Pre-bending process) As shown in Fig. 7, the press forming apparatus 1 used in the preliminary bending step S1 includes a drive unit 10, a punch 2, a die 3, a presser member 4, and a support unit 5. The punch 2 is configured to be movable in the vertical direction by the drive unit 10. The drive unit 10 is controlled by a control device (not shown) configured by, for example, a computer or an ECU. The punch 2 includes, as a processing surface (lower surface), a top surface 2y corresponding to the top plate portion 811, and shoulder surfaces 2z located on the left and right of the top surface 2y and corresponding to the inclined wall portion 812.

[0059] The die 3 is disposed so as to face the punch 2. The die 3 is disposed below the punch 2. The die 3 is composed of two die members 31 and 32. Each of the die members 31 and 32 has an inclined surface 3a formed thereon corresponding to the inclined wall portion 812. The inclined surface 3a is disposed so as to face the shoulder surface 2z of the punch 2.

[0060] The pressing member 4 is disposed so as to face the top surface 2y of the punch 2. The pressing member 4 is disposed below the punch 2. The pressing member 4 is disposed between the two die members 31 and 32. The processing surface (upper surface) of the pressing member 4 corresponds to the top plate portion 811. The pressing member 4 can be said to be a portion on which the plate material 80 is placed before the preliminary bending process S1 is performed.

[0061] The support device 5 is a device that supports the presser member 4. The support device 5 is disposed below the presser member 4. The support device 5 supports the presser member 4 so that it can move downward. The support device 5 applies an upward force to the presser member 4 as it moves downward. The support device 5 is configured to include, for example, a fluid cylinder such as an air cylinder or a hydraulic cylinder, or a spring. When the support device 5 is, for example, a spring, the spring directly or indirectly abuts against the presser member 4 and applies an upward force to the presser member 4 as it moves downward, depending on the amount of compression and spring constant of the spring.

[0062] As shown in FIG. 7, in the preliminary bending step S1, the plate material 80 is placed on the presser member 4. The plate material 80 extends above both inclined surfaces 3a. Then, as shown in FIG. 8, the driving device 10 moves the punch 2 downward, and the top surface 2y comes into contact with the plate material 80. The plate material 80 is sandwiched between the punch 2 and the presser member 4. Then, as shown in FIG. 9, the driving device 10 moves the punch 2 downward together with the plate material 80 and the presser member 4 while receiving the force of the support device 5. As the punch 2 moves downward, the central portion of the plate material 80 moves downward. As the punch 2 moves downward, the left and right ends of the plate material 80 are bent to follow the inclined surfaces 3a.

[0063] Ultimately, the left and right ends of the plate material 80 are sandwiched between the shoulder surface 2z and the inclined surface 3a of the punch 2 to form the inclined wall portions 812 of the preformed product 81. The left-right central portion of the plate material 80 is sandwiched between the top surface 2y of the punch 2 and the pressing member 4 to form the top plate portion 811 of the preformed product 81. The inclined wall portions 812 of the preformed product 81 are inclined in a predetermined rotational direction relative to the top plate portion 811. In this embodiment, the inclined wall portion 812 on the left side of the preformed product 81 is inclined clockwise relative to the top plate portion 811. Furthermore, the inclined wall portion 812 on the right side of the preformed product 81 is inclined counterclockwise relative to the top plate portion 811.

[0064] In this way, the pre-bending step S1 is a step in which the plate material 80 is bent in a predetermined rotation direction by the press forming apparatus 1 to form a preformed product 81. In the pre-bending step S1, the plate material 80 is bent in the predetermined rotation direction so that the bending angle of the plate material 80 is less than 90°, that is, so that the bending angle is an acute angle (0°<bending angle<90°).

[0065] (Specific bending process) 10, the press forming apparatus 1A used in the specific bending process S2 includes a drive device 10A, a punch 2A, a pressing member 4A, support devices 51 and 52, cam sliders (abutment members) 71 and 72, and cam drivers 73 and 74. The punch 2A is connected to a support member 11 via the support device 51. The punch 2A is disposed between the cam drivers 73 and 74.

[0066] 10 and 11, the punch 2A includes a main body 21A and shoulders 22A formed on the left and right sides of the main body 21A. The right shoulder 22A bulges rightward from the right side of the lower end of the main body 21A. The left shoulder 22A bulges leftward from the left side of the lower end of the main body 21A. Each shoulder 22A protrudes from the lower end of the main body 21A.

[0067] The punch 2A has, as processing surfaces, a top surface 2a corresponding to the top plate portion 811 of the press-formed product 9, a shoulder surface 2b corresponding to the shoulder R portion 92 of the press-formed product 9, and a side wall surface 2c corresponding to the vertical wall portion 93 of the press-formed product 9. The punch 2A has one top surface 2a, a pair of shoulder surfaces 2b, and a pair of side wall surfaces 2c. The top surface 2a is the lower surface of the main body portion 21A. The top surface 2a is formed in a shape corresponding to the top plate portion 811.

[0068] One shoulder surface 2b is formed continuously from the left end of the top surface 2a, and the other shoulder surface 2b is formed continuously from the right end of the top surface 2a. Each shoulder surface 2b is formed on the surface of the lower end of the corresponding shoulder portion 22A, i.e., the curved portion of the lower end of the shoulder portion 22A. Each shoulder surface 2b is formed in a curved shape corresponding to the shoulder R portion 92. Each side wall surface 2c is formed on the side surface of the corresponding shoulder portion 22A. Each side wall surface 2c is formed in a planar shape corresponding to the vertical wall portion 93. The right side wall surface 2c is a side surface of the right shoulder portion 22A and extends upward continuously from the right shoulder surface 2b. The left side wall surface 2c is a side surface of the left shoulder portion 22A and extends upward continuously from the left shoulder surface 2b.

[0069] Each shoulder 22A protrudes from a side surface at the lower end of the main body 21A. Therefore, on each of the left and right side surfaces of the punch 2A, the shoulder 22A and the main body 21A form a relief portion 20. On each side surface of the punch 2A, a portion recessed toward the center (i.e., relief portion 20) is formed at a position corresponding to the protrusion 70 (above the side wall surface 2c).

[0070] The pressing member 4A is disposed so as to face the punch 2A. The pressing member 4A is disposed below the punch 2A. The pressing member 4A is disposed between the cam sliders 71 and 72. The processing surface (upper surface) of the pressing member 4A is formed into a shape corresponding to the top plate portion 811. The pressing member 4A can be said to be a portion on which the preformed product 81 is placed before the specific bending process S2 is performed.

[0071] The support device 51 is disposed between the punch 2A and the support member 11, and supports the punch 2A so that it can move upward. The support device 51 includes, for example, a spring or a fluid cylinder. When the punch 2A attempts to approach the support member 11, the support device 51 applies a force to the punch 2A to prevent the approach. In other words, when the punch 2A attempts to move upward relative to the support member 11, the support device 51 applies a downward force (for example, a spring force) to the punch 2A. Like the support devices 5 and 51, the support device 52 also includes, for example, a spring or a fluid cylinder. The support device 52 supports the presser member 4A so that it can move downward.

[0072] The cam sliders 71 and 72 are disposed opposite each other. The cam slider 71 is disposed on the right side of the pressing member 4A, and the cam slider 72 is disposed on the left side of the pressing member 4A. Each of the cam sliders 71 and 72 is formed with an inclined surface 7a.

[0073] Each cam driver 73, 74 is a member for moving the corresponding cam slider 71, 72. Each cam driver 73, 74 is arranged above the corresponding cam slider 71, 72 so as to be movable in the up and down direction. The cam drivers 73, 74 are connected to the support member 11. The cam driver 73 corresponds to the cam slider 71 and is arranged on the right side of the punch 2A. The cam driver 74 corresponds to the cam slider 72 and is arranged on the left side of the punch 2A. Each cam driver 73, 74 is formed with a slope 7b corresponding to the slope 7a.

[0074] Cam slider 71 moves in a direction approaching presser member 4A (to the left) as cam driver 73 moves downward with its own inclined surface 7a in contact with inclined surface 7b of cam driver 73. Cam slider 72 moves in a direction approaching presser member 4A (to the right) as cam driver 74 moves downward with its own inclined surface 7a in contact with inclined surface 7b of cam driver 74.

[0075] The cam slider 71 is provided with a spring (not shown) that biases the cam slider 71 in a direction (rightward) away from the pressing member 4A. Similarly, the cam slider 72 is provided with a spring (not shown) that biases the cam slider 72 in a direction (leftward) away from the pressing member 4A. Each cam driver 73, 74 overcomes the force of the spring to move the corresponding cam slider 71, 72. When the cam sliders 71, 72 are released from contact with the cam drivers 73, 74, they move in directions away from each other toward their initial positions. When the cam sliders 71, 72 are not in contact with the cam drivers 73, 74, they are returned to their predetermined initial positions by the spring. Note that the biasing force applied to the cam sliders 71, 72 is not limited to a spring, and other biasing members or biasing devices may also be used.

[0076] As shown in FIGS. 10 and 11 , abutment surfaces 7z corresponding to the shoulder portion 22A of the punch 2A are formed on the side surfaces 71a, 72a of each cam slider 71, 72 facing the punch 2A. The abutment surfaces 7z are formed to correspond to the shoulder R portion 92 and the vertical wall portion 93 of the press-formed product 9. The abutment surfaces 7z have a shape recessed (concave) from the side surfaces of each cam slider 71, 72. A protrusion 70 protruding toward the punch 2A is formed on each side surface 71a, 72a at a position adjacent to the abutment surface 7z (upper portion in FIG. 6 ). In other words, a protrusion 70 protruding toward the opposing cam slider 71, 72 is formed at a position adjacent to the end (upper end) of the abutment surface 7z opposite the shoulder R portion 92. Each protrusion 70 is formed on the corresponding side surface 71a, 72a at a position corresponding to the tip position of the vertical wall portion 93 of the press-formed product 9. The abutment surface 7z and the protrusion 70 can be said to form recesses in the side surfaces 71a and 72a of the cam sliders 71 and 72.

[0077] The drive device 10A is a device that moves at least one of the punch 2A and the presser member 4A in the vertical direction (a predetermined direction) and moves the cam sliders 71 and 72 in the left-right direction (a direction intersecting the predetermined direction). The drive device 10A of this embodiment is a device that moves the support member 11 in the vertical direction. By moving the support member 11 in the vertical direction, the drive device 10A moves the punch 2A in the vertical direction and moves the cam sliders 71 and 72 in the left-right direction. The drive device 10A is configured to perform the specific bending process S2.

[0078] 10, before the specific bending step S2 is performed, the preform 81 is placed on the pressing member 4A so that the inclined wall portion 812 is located on the punch 2A side (above) with respect to the top plate portion 811. The top plate portion 811 is placed on the pressing member 4A, and the inclined wall portion 812 is in a floating state.

[0079] As shown in FIG. 12, the drive unit 10A moves the punch 2A downward, bringing the punch 2A into contact with the preformed product 81. The punch 2A moves downward while pressing the preformed product 81 and the presser member 4A. When the presser member 4A reaches its lowest point, the support unit 51 contracts, and the punch 2A does not move downward even if the support member 11 moves downward. In other words, in this state, the preformed product 81 is positioned. In this example, when the preformed product 81 is positioned, the cam sliders 71, 72 are not in contact with the inclined wall portion 812.

[0080] As the support member 11 moves downward, the cam drivers 73, 74 also move downward. Each cam driver 73, 74 comes into contact with the corresponding cam slider 71, 72, and moves the corresponding cam slider 71, 72 in a direction approaching the preformed product 81. As shown in Fig. 12, when the preformed product 81 is positioned, the shoulder portion 22A of the punch 2A faces the abutment surfaces 7z of the cam sliders 71, 72, and the relief portion 20 of the punch 2A faces the protrusions 70 of the cam sliders 71, 72.

[0081] As the cam sliders 71, 72 move further, the tip end 812a of the inclined wall portion 812 comes into contact with the abutment surface 7z and is bent along the abutment surface 7z toward the protrusion 70. As shown in Fig. 13, as the cam sliders 71, 72 move, the tip end surface 812b of the inclined wall portion 812 comes into contact with the pressing surface 70a located on the abutment surface 7z side of the protrusion 70.

[0082] In this state, when the cam sliders 71 and 72 approach the punch 2A, the inclined wall portion 812 is bent, causing the tip surface 812b of the inclined wall portion 812 to move upward, but the pressing surface 70a prevents this movement. In other words, the tip surface 812b of the inclined wall portion 812 is pressed downward by the pressing surface 70a of the protruding portion 70. When the inclined wall portion 812 is bent, a force is applied to the tip surface 812b of the inclined wall portion 812 in a direction that reduces the plate length of the inclined wall portion 812 (downward in this example). This force is referred to as a "compression force." When the inclined wall portion 812 is bent, a pressing force (i.e., a compression force) is applied to the tip surface 812b of the inclined wall portion 812 in a direction perpendicular to the tip surface 812b of the inclined wall portion 812. The average pressure applied to the tip surface 812b is referred to as an "end pressure."

[0083] The compressive force can be said to be a force in a direction perpendicular to the tip surface 812b of the inclined wall portion 812. Alternatively, the compressive force can be said to be a force compressing the tip portion 812a of the inclined wall portion 812 in the plate length direction. Hereinafter, the formed inclined wall portion 812 (e.g., the shoulder R portion 92 and the vertical wall portion 93) will also be referred to as a "flange."

[0084] For example, while bending the inclined wall portion 812, a compressive force that generates a yield stress in the bent portion of the inclined wall portion 812 is applied to the front end surface 812b. As a result, as shown in FIG. 24, for example, at the front end 812a of the stretch flange, a reduction in the thickness of the inclined wall portion 812 due to bending is suppressed. Unlike a contraction flange or a straight flange, the front end (front end 812a) of a stretch flange is prone to a reduction in thickness due to bending. However, according to the present method, a reduction in the thickness of the front end 812a is suppressed. In the specific bending step S2, the press forming apparatus 1A bends the inclined wall portion 812 while applying a compressive force that causes yielding to the front end surface 812b, thereby bending the inclined wall portion 812 in the predetermined rotational direction while suppressing a reduction in the thickness of the inclined wall portion 812 in the stretch flange. Even when the compressive force is smaller than the force corresponding to yield, the circumferential tensile stress of the stretch flange is reduced, and the occurrence of necking is delayed. In addition, applying a compressive force can suppress the progression of voids and cracks. Note that bending increases the plate thickness at the contracted flange and linear bend, creating a compressive stress field in the plate length direction. As a result, the circumferential compressive stress at the contracted flange decreases, suppressing shape deformation. Elastic recovery occurs in the plate length direction, but no significant dimensional difference occurs. Linear bending causes elastic recovery in the plate length direction, but no significant dimensional difference occurs.

[0085] Regardless of the shape of the flange, such as a stretch flange, a contraction flange, or a straight flange, the plate length of the inclined wall portion 812 (flange) is actually reduced by bending the inclined wall portion 812 while applying a compressive yield stress to the bent portion of the inclined wall portion 812. In this case, the plate length of the press-formed product 9 becomes shorter than the plate length of the preformed product 81. In other words, the plate material 80 or the preformed product 81 has a compression allowance provided in accordance with the target shape of the press-formed product 9 (see FIG. 22).

[0086] 14, the preform 81 is finally sandwiched between the cam sliders 71 and 72, the punch 2A, and the pressing member 4A to become the press-formed product 9. At this time, the protrusions 70 of the cam sliders 71 and 72 are inserted into the corresponding relief portions 20 of the punch 2A.

[0087] In this way, the specific bending process S2 is a process in which the press forming apparatus 1A bends the inclined wall portion 812 in a predetermined rotation direction while applying a compressive force to the tip end surface 812b of the inclined wall portion 812. As an example, the specific bending process S2 is a process in which the inclined wall portion 812 is bent in a predetermined rotation direction while suppressing a decrease in the plate thickness of the inclined wall portion 812 or while increasing the plate thickness of the inclined wall portion 812 by applying a compressive force (a force that reaches the yield stress) to the tip end surface 812b. The specific bending process S2 in this example is a process in which the inclined wall portion 812 is bent in a predetermined rotation direction while reducing the plate length of the inclined wall portion 812 by applying a compressive force (a force that reaches the yield stress) to the tip end surface 812b.

[0088] (summary) The press-forming method of the present disclosure is a press-forming method using a press-forming apparatus 1A, and includes a specific bending step S2 in which, with the top plate portion 811 fixed, a preform 81 includes a top plate portion 811 and a slanted wall portion 812 slanted in a predetermined rotational direction relative to the top plate portion 811, while applying a compressive force to a tip end surface 812b of the slanted wall portion 812, bending the slanted wall portion 812 in the predetermined rotational direction. The top plate portion 811 remains fixed (immobile) throughout the forming process. In other words, the top plate portion 811 is fixed by the press-forming apparatus 1A throughout the forming process so that the top plate portion 811 does not move during the forming process. The compressive force may be a force that does not cause yielding in the plate material.

[0089] The press-forming method of the present disclosure includes a preliminary bending step S1 and a specific bending step S2. The preliminary bending step S1 is a step of bending a plate material 80 in a predetermined rotational direction to form a preformed product 81. The specific bending step S2 is a step of bending the inclined wall portion 812 in the predetermined rotational direction while applying a compressive force to a tip end surface 812b of the inclined wall portion 812 with the top plate portion 811 fixed, to form a shoulder R portion 92 and a vertical wall portion 93, in order to form a press-formed product 9 from the preformed product 81.

[0090] The press forming apparatus 1A includes a die member 2A (e.g., a punch 2A), a presser member 4A, butting members 71 and 72 (e.g., cam sliders 71 and 72), and a drive unit 10A. The die member 2A has a top surface 2a corresponding to the top plate portion 811, a shoulder surface 2b corresponding to the shoulder R portion 92, and a side wall surface 2c corresponding to the vertical wall portion 93. The presser member 4A is disposed below the top surface 2a (on one side in a predetermined direction) so as to face the top surface 2a. The butting members 71 and 72 face the side wall surface 2c and face the vertical wall portion 93. The drive unit 10A moves the butting members 71 and 72 in the left-right direction (a direction intersecting the predetermined direction). The butting members 71 and 72 have protrusions 70 that protrude toward the die member 2A at positions corresponding to the tip positions of the vertical wall portions 93 on the butting members 71 and 72. In the specific bending process S2, with the top plate portion 811 of the preformed product 81 sandwiched between the top surface 2a and the pressing member 4A, and with the tip surface 812b of the inclined wall portion 812 abutting against the pressing surface 70a, which is the lower end surface (end surface on one side in a predetermined direction) of the protrusion 70, the drive unit 10A moves the abutment members 71, 72 toward the side wall surface 2c.

[0091] A relief portion 20 into which the protruding portion 70 can enter is formed in a portion of the mold member 2A corresponding to the protruding portion 70. In the specific bending process S2, with the top plate portion 811 of the preform 81 sandwiched between the top surface 2a and the pressing member 4A and with the tip surface 812b of the inclined wall portion 812 abutting against the pressing surface 70a of the protruding portion 70, the driving device 10A moves the abutting member 4A toward the side wall surface 2c, causing the protruding portion 70 to enter the relief portion 20.

[0092] In the press forming apparatus 1A of the present disclosure, the protrusion 70 is formed so that the pressing surface 70a comes into contact with the tip end surface 812b of the inclined wall portion 812 when the inclined wall portion 812 is bent to form the shoulder R portion 92 and the vertical wall portion 93. The pressing surface 70a of the protrusion 70 is formed so as to apply a force (i.e., a compressive force) to the tip end surface 812b of the inclined wall portion 812 in a direction that reduces the plate length of the inclined wall portion 812 as the abutting members 71, 72 move (approach the die member 2A). The abutting members 71, 72 in this embodiment are cam sliders 71, 72 that move in conjunction with the movement of the cam drivers 73, 74.

[0093] (Transformation mode) The configuration of the press-forming apparatus 1A used in the specific bending step S2 is not limited to the above embodiment and may be configured as shown in FIG. 15. This press-forming apparatus 1A also includes a mold member 2A, a press member 4A, a butting member 71, and a drive device (not shown) for moving the press member 4A. FIG. 15(a) shows a state in which a top plate portion 811 of a preformed product 81 is sandwiched and fixed between the top surface 2a of the mold member 2A and the press member 4A. FIG. 15(b) shows a state in which the butting member 71 has moved leftward, causing the tip end 812a of the inclined wall portion 812 to abut against the abutment surface 7z. FIG. 15(c) shows a state in which the butting member 71 has moved further leftward, causing the inclined wall portion 812 to bend, causing the tip end surface 812b to abut against the pressing surface 70a of the protrusion 70. 15(d) shows a state in which the abutting member 71 has moved further leftward, and end pressure has been applied to the tip end surface 812b, bending the inclined wall portion 812. Also, FIG. 15(d) shows a state in which the protrusion 70 has entered the relief portion 20, and the inclined wall portion 812 has been sandwiched between the shoulder surface 2b, the side wall surface 2c, and the abutting surface 7z, deforming into the shoulder R portion 92 and the vertical wall portion 93.

[0094] The press forming apparatus 1A used in the specific bending step S2 may also have a configuration as shown in Fig. 16. This press forming apparatus 1A also includes a die member 2A, a pressing member 4A, a butting member 71, and a drive device (not shown) that moves the butting member 71. In this example, the pressing member 4A has, in addition to a top surface 41 corresponding to the top plate portion 811, a shoulder pressing surface 42 that corresponds to at least a part of the shoulder R portion 92. Furthermore, when the butting member 71 moves leftward, it also moves downward. In other words, the butting member 71 moves obliquely relative to the die member 2A.

[0095] In the example of FIG. 16 , a compression allowance is provided in the sheet material 80 or the preformed product 81 to take into account the reduction in sheet length due to compression force. In the press-forming method of this embodiment, the sheet material 80 or the preformed product 81 is bent while being compressed, thereby being formed into the target shape (the shoulder R portion 92 and the vertical wall portion 93). The sheet length of the sheet material 80 or the preformed product 81 includes a compression allowance corresponding to the amount of compression (reduction) in the specific bending process S2, and is longer than the sheet length of the target shape by the amount of compression in the specific bending process S2. The two-dot chain arrow in FIG. 12 indicates the path of the leading end surface 812b in the case where no compression is performed, and the solid arrow indicates the path of the leading end surface 812b in the case where compression is performed. The reduction in sheet length corresponds to the compression allowance. Providing a compression allowance in the sheet material 80 or the preformed product 81 and bending the sheet material 80 or the preformed product 81 while compressing it by the compression allowance in this manner can be applied to all embodiments of the present disclosure. Providing a compression allowance for the plate length of the target shape and bending the plate while compressing it by the compression allowance to form the target shape is equivalent to bending the plate while generating yield stress within the plate material 80 or preformed product 81 through compression.

[0096] As described above, in one technique disclosed herein, in the specific bending process S2, a compressive force is applied to the tip end surface 812b of the inclined wall portion 812 so that the average pressure (end pressure) applied to the tip end surface 812b of the inclined wall portion 812 reaches the yield stress of the inclined wall portion 812. The preformed product 81 is provided with a compression allowance for compression by the compressive force, and the plate length of the inclined wall portion 812 before the specific bending process S2 is performed is greater than the plate length of the inclined wall portion 812 (the shoulder R portion 92 and the vertical wall portion 93) after the specific bending process S2 is performed. In the present disclosure, the plate material 80 is provided with a compression allowance for compression by the compressive force, and the plate length of the inclined wall portion 812 is greater than the plate lengths of the shoulder R portion 92 and the vertical wall portion 93.

[0097] 17, in the preliminary bending step S1, the tip end 812a of the inclined wall portion 812 may be bent in a predetermined rotational direction so that the tip end surface 812b faces the pressing surface 70a of the protrusion 70, i.e., so that the tip end surface 812b faces the pressing surface 70a. This process is called an end bending process. The pressing surface 70a and the tip end surface 812b face each other in the vertical direction (predetermined direction). In this way, the shape of the inclined wall portion 812 may be changed depending on, for example, the shape of the vertical wall portion 93 or the like (the shape of the stretch flange). In the preliminary bending step S1, the press forming apparatus bends the tip end 812a of the inclined wall portion 812 in a predetermined rotational direction so that the tip end surface 812b of the inclined wall portion 812 faces downward (the other side of the predetermined direction).

[0098] As an example of the end bending process, as shown in FIG. 18, a press forming apparatus 1B is configured by replacing the die 3 with a die 3B in the configuration of the press forming apparatus 1. The die 3B includes die members 31B and 32B. Each die member 31B and 32B includes a side surface 3b extending upward from an inclined surface 3a. In the end bending process, press forming is performed so that the tip end 812a of the inclined wall portion 812 is sandwiched between the side surface 3b of each die member 31B and 32B and the side surface of the punch 2. In other words, when the preliminary bending step S1 is performed, the end bending process is also performed simultaneously. As a result, both end portions of the sheet material 80 are bent in a predetermined rotation direction to form the inclined wall portions 812, and the tip end 812a of the inclined wall portion 812 is further bent in the predetermined rotation direction. In the example of FIG. 18, the tip end 812a of the inclined wall portion 812 extends along the side surface of the punch 2. According to the end bending process, the pressing surface 70a of the protrusion 70 and the tip surface 812b of the inclined wall portion 812 are likely to come into contact with each other during the specific bending step S2, and compressive force can be applied to the tip surface 812b more efficiently. Note that the punch may also be replaced in conjunction with the replacement of the die.

[0099] According to the press-forming method of the present disclosure, by bending the inclined wall portion 812 while applying a compressive force to the tip surface 812b of the inclined wall portion 812, the stress distribution in the bent portion of the inclined wall portion 812 increases the compressive stress in the compressive stress region (the inner portion of the bend) and decreases the tensile stress in the tensile stress region (the outer portion of the bend). The decrease in tensile stress reduces the bending moment generated in the bent portion of the inclined wall portion 812, and also reduces the amount of springback. In other words, according to the press-forming method of this embodiment, springback is suppressed. Furthermore, by simultaneously performing "bending" and "application of a compressive force" on the inclined wall portion 812 (in one process), the complexity of the process can be reduced. Furthermore, according to the press-forming apparatus 1A of this embodiment, the protrusion 70 abuts against the tip surface 812b of the inclined wall portion 812 during bending, and therefore the specific bending process S2 can be performed. Therefore, the same effects as those of the above-described method can be achieved.

[0100] Furthermore, when the compressive force corresponds to the yield stress of the inclined wall portion 812 (in other words, when the end pressure reaches the yield stress), bending is performed while suppressing a decrease in the thickness of the inclined wall portion 812 due to bending or while increasing the thickness of the inclined wall portion 812. As a result, necking occurs more slowly than in conventional forming methods. Even if necking occurs, the fracture strain increases due to the increase in compressive stress within the plate, improving formability. In other words, even if necking occurs, voids are prevented from growing and cracks are prevented from progressing, delaying the occurrence of cracks. Hereinafter, the compressive force corresponding to the yield stress will also be referred to as the "yield compressive force."

[0101] In the specific bending process S2, in which a yield compressive force is applied to the tip surface 812b, the shoulder R portion 92 is plastically compressed, and the stress that was non-uniform within the plate during bending deformation approaches uniform compressive stress. Even after unloading, the stress decreases uniformly, reducing residual stress. This suppresses springback. In theory, unloading reduces residual stress to zero.

[0102] When a sheet material is bent without applying a compressive force as in the conventional method, the stress distribution within the sheet is such that tensile stress is distributed on the outer side of the bend and compressive stress is distributed on the inner side of the bend, as shown in Figure 19. When a load is applied to the sheet material by the press-forming device 1A (i.e., before unloading), a moment M corresponding to the stress distribution is applied to the sheet material. When this load is released, a moment in the opposite direction to moment M is applied, causing springback. On the other hand, when a sheet material is bent while applying a yield compressive force to the sheet material, theoretically, compressive stress is distributed even on the outer side of the bend, as shown in Figure 20, and compressive stress is distributed throughout the entire area. As a result, even after unloading, the line showing the stress distribution in the stress state in Figure 20 simply moves toward the central dotted line, and no moment is generated, and no springback occurs. When the end pressure (the average pressure applied to the tip surface 812b) becomes the yield stress, theoretically, springback becomes zero. Even when the compressive force is smaller than the yield compressive force, the tensile stress in the outer bent portion in FIG. 19 can be reduced, thereby reducing the moment M. In other words, the springback after unloading in this case is smaller than when no compressive force is applied during bending. A compression allowance is not necessary. In this way, by bending the plate while applying a compressive force to a specific end face of the plate, the stress distribution in the outer bent portion can be shifted closer to the compressive side, thereby suppressing springback. According to this embodiment, the uneven stress distribution in the plate caused by bending can be shifted closer to a uniform stress distribution. A uniform stress distribution can be defined as a state in which compressive stress is distributed throughout the entire bent portion (from the inner periphery to the outer periphery), as shown in FIG. 16, for example. In other words, a uniform stress distribution can be defined as a state in which the entire stress distribution in the bent portion is compressive stress (a state in which no tensile stress is generated). For the effects of this embodiment, see FIG. 21.

[0103] As shown in FIG. 22, the plate material (80) may have a curved shape before bending. In this example, the right end of the plate material bulges to the right, and the left end of the plate material is recessed to the right. It is also possible to bend a plate material with such a shape in a predetermined rotation direction (the rotation axis extends in the front-to-rear direction). For example, shrinkage flanges are relatively prone to wrinkles, while stretch flanges are relatively prone to cracks (see FIG. 24). However, according to this embodiment, even for plate materials with complex shapes, wrinkles and cracks can be suppressed by bending the plate material while applying a compressive force. In the example of FIG. 22, as shown by the dotted line, a compression allowance is provided relative to the plate length (left-to-right direction) of the plate material. The dimensions indicated by the dotted line are the actual dimensions of the press-formed product. By compressing and bending the plate material as in this embodiment, not only springback but also wrinkles and cracks can be suppressed, even for plate materials with complex shapes.

[0104] As described above, the press forming method of this embodiment makes it possible to suppress cracking and springback. It also makes it possible to suppress jerk, twisting of the top plate portion 811, and shrinkage flange wrinkles that occur during bending. Furthermore, applying a yield compressive force to the end face of the plate material smooths out any irregularities on the end face. This embodiment makes it possible to suppress cracking (fracture), suppress bending springback, suppress wrinkles, improve end face properties, and improve forming accuracy. The press forming method and press forming apparatus 1A of this embodiment make it possible to suppress springback, suppress twisting of the top plate portion, suppress wrinkles, suppress cracking, and reduce residual stress while preventing the process from becoming too complicated.

[0105] (others) The present invention is not limited to the above embodiment. For example, the mold member 2A may not have the relief portion 20. For example, the press-forming apparatus may be configured so that, in the specific bending step S2, the vertical wall portion 93 is formed at the position where the protrusion 70 abuts against the mold member 2A or just before the abutment. However, as in the above embodiment, the presence of the relief portion 20 allows the inclined wall portion 812 (vertical wall portion 93) to be more reliably sandwiched between the mold member 2A and the abutment members 71 and 72, thereby improving the forming accuracy of the vertical wall portion 93.

[0106] The arrangement of the molds and other components of the apparatus disclosed herein may be reversed. The multiple components that contact the workpiece during press forming may be referred to as mold components (punches, dies, pads, etc.) as appropriate. This technology can also accommodate increasingly complex product shapes. The vertical wall portion 93 may also be referred to as a flange. For example, the top plate portions 811 and 91 may have grooves or irregularities. The press forming method or press forming apparatus disclosed herein can accurately manufacture metal vehicle parts, such as lower arms, axle beams, and interior parts. This technology can be applied to all types of bending. Furthermore, forming using the molds disclosed herein may also be referred to as closed bending or closed cam bending. The press forming method disclosed herein may also include a process of bending the tip of the preform 81 while applying pressure (cam bending) in a closed space. The press forming method disclosed herein may also be referred to as an end pressure closed cam bending method. The thickness direction of a plate may be referred to as the plate thickness direction, and the direction perpendicular to the plate thickness direction may be referred to as the plate length direction.

[0107] The technology of the present disclosure can also be described as follows. The forming method of the present disclosure is a forming method for bending a sheet material (e.g., 80, 81) using a forming device, characterized in that the forming device applies a compressive force to the sheet material in a direction that reduces the sheet material's length, while bending the sheet material in a predetermined rotational direction so that the bending rotation axis extends in a direction intersecting the sheet material's reduction direction (the direction of the compressive force). This allows the non-uniform stress generated in the sheet material due to bending plastic deformation to approach a uniform compressive stress, thereby suppressing springback, as described above. As shown in FIG. 23 , the rotation axis (virtual line) indicating the center of rotation in the predetermined rotational direction extends in a direction intersecting the reduction direction (which can also be referred to as the compression direction). In other words, the center line of the bending of the sheet material extends in a direction intersecting the reduction direction. The sheet material length can be considered as the length in a direction perpendicular to the sheet material's thickness direction. Furthermore, the forming device is not limited to a press forming device, and may be, for example, a device using a robot arm. For example, a robot arm may grasp the plate material and bend it while reducing its length. In this way, various forming devices may bend the plate material in a predetermined rotational direction while reducing its length with a compressive force corresponding to yield. By bending the plate material while reducing its length, i.e., while applying compressive yield stress to the plate material, it is possible to more reliably bring the uneven stress distribution in the plate caused by bending closer to a uniform stress distribution. This allows for precise suppression of springback.

[0108] The technology of the present disclosure can also be described as follows. The method of the present disclosure is a forming method for bending a plate material (e.g., 80, 81) using a forming device, characterized in that the forming device bends the plate material in a predetermined rotational direction so that the bending rotation axis extends in a direction intersecting the compression direction while applying a compressive force (i.e., yield compressive force) to a predetermined end face (e.g., tip end face 812b) of the plate material in a compressive direction that reduces the plate material's length and that generates a yield stress in the plate material. This also achieves the same effect as described above. Note that the predetermined end face of the plate material is not limited to tip end face 812b.

[0109] The technology of the present disclosure can also be described as follows. The method of the present disclosure is a forming method using a forming device to bend a plate material, characterized in that the forming device bends the plate material in a predetermined rotational direction while applying a force to the plate material in a direction that reduces the plate length so as to convert non-uniform stress generated in the plate material due to bending plastic deformation into a uniform compressive stress (first embodiment). In the forming method of the first embodiment, the forming device bends the plate material in the predetermined rotational direction while applying a compressive force that causes yielding to a predetermined end face of the plate material (second embodiment). In the forming method of the first or second embodiment, the plate material is a preformed product including a top plate portion and an inclined wall portion inclined relative to the top plate portion in the predetermined rotational direction, and the forming device, with the top plate portion fixed, bends the inclined wall portion in the predetermined rotational direction while applying a force to a tip face of the inclined wall portion in a direction that reduces the plate length of the inclined wall portion.

[0110] (Regarding Related Art and This Embodiment) The above-mentioned related technologies can be said to use the press forming method of this embodiment. For example, the first bending process starts from the state shown in FIG. 11, and the second bending process starts from the state shown in FIG. 13. Also, (b) and (c) in FIG. 15 correspond to the first bending process, and (c) and (d) in FIG. 15 correspond to the second bending process. These related technologies can also be designed so that the inner surface of the inclined wall portion 812 does not contact the punch 2A. For example, the punch 2A corresponds to the punch Z11, and the pressing member 4A corresponds to the pad Z12. The cam sliders (abutment members) 71 and 72 correspond to the dies Z21 and Z22 (mold member Z2). The drive unit 10A corresponds to the drive unit Z3. The operating mechanism of the press forming apparatus Z can be referred to, for example, in the operating mechanism of the press forming apparatus 1A, and therefore detailed description thereof is omitted. This embodiment and the related technologies can achieve at least some of the same effects.

[0111] The press forming apparatus Z of this embodiment may be equipped with a cam mechanism, as in the related art. That is, the press forming apparatus Z may be equipped with cam drivers 73, 74 that link the vertical movement of the fixed member Z1 with the left-right movement of the die member Z2. In this case, the die member Z2 (dies Z21, Z22) functions as a cam slider (71, 72) corresponding to the cam drivers 73, 74. In this case, the drive unit Z3 moves the fixed member Z1 up and down, thereby moving the die member Z2 left and right so as to approach the fixed member Z1. In the method and apparatus of this embodiment, by using such a cam mechanism, the die member Z2 can be smoothly moved diagonally (in the vertical and left-right directions) relative to one another. [Explanation of symbols]

[0112] Z, 1A...press forming device, Z3, 10A...drive device, Z11, 2A...punch (fixed member, one member), Z11a...contact portion, Z12...pad, Z12a...forming recess, Z2...mold member, Z21, Z22...die, Z2a...forming side surface, Z2b...engagement portion, 71, 72...cam slider (mold member), 73, 74...cam driver, 4A...holding member (fixed member, other member), 81...preliminary formed product, 811...top plate portion, 812...inclined wall portion, 812b...tip surface.

Claims

1. A press molding method using a press molding device for a preform having a top plate portion and an inclined wall portion inclined in a predetermined rotational direction relative to the top plate portion, the press molding method including: a fixing member that clamps and fixes the top plate portion; and a mold member having a molding side surface formed to match a target shape of the inclined wall portion, a first bending step in which the top plate portion is fixed by the fixing member so that it does not move during molding, and in which at least a part of the outer surface of the inclined wall portion is abutted against the molding side surface, by moving the mold member toward the fixing member, causing the inclined wall portion to protrude toward the molding side surface and deforming the inclined wall portion along the molding side surface; a second bending process in which, while maintaining the state of the first bending process, a compressive force, which is a force in a direction to reduce the plate length of the inclined wall portion, is applied to the tip surface by contacting the tip surface of the inclined wall portion with a part of the press forming device, and the inclined wall portion is bent into a shape along the forming side surface; A press molding method comprising:

2. the inclined wall portion includes a first inclined wall portion inclined in the predetermined rotation direction with respect to the top plate portion, and a second inclined wall portion inclined in the predetermined rotation direction with respect to the first inclined wall portion on a tip side of the first inclined wall portion, In the first bending step, a contact surface, which is at least a part of the outer surface of the second inclined wall portion, is in contact with the forming side surface, and a partial compressive force, which is a force in a direction to reduce the plate length of the first inclined wall portion, is applied to the contact surface to deform the inclined wall portion, In the second bending step, the tip end of the inclined wall portion is guided by the forming side surface and moves, and as a result, the tip end surface comes into contact with an abutment portion that is a part of the fixing member, thereby generating the compressive force. The press molding method according to claim 1 .

3. the fixing member includes one member having the abutment portion and another member disposed opposite the one member, the other member has a molding recess formed in accordance with a target shape of the curved portion of the top plate portion and the first inclined wall portion, In the first bending step and the second bending step, the top plate portion and the curved portion are maintained in a state of being accommodated in the molding recess. The press molding method according to claim 2 .

4. The fixing member has a protrusion protruding from the molding side surface, In the second bending step, as a result of the tip end of the inclined wall portion being guided by the forming side surface and moving in the first bending step, the tip end surface comes into contact with the protruding portion, and the tip end surface receives the compressive force from the protruding portion. The press molding method according to claim 1 .

5. In the first bending process and the second bending process, an inner surface of the inclined wall portion does not come into contact with the press forming device. The press molding method according to any one of claims 1 to 4.

6. the mold member includes an engaging portion that protrudes from the molding side surface and engages with the tip end of the inclined wall portion so that the tip end of the inclined wall portion is aligned with the molding side surface, In the first bending step and the second bending step, a state in which the tip end of the inclined wall portion is engaged with the engaging portion is maintained, At least in the second bending step, the compressive force is generated by contact between the engaging portion and the tip end surface. The press molding method according to claim 1 .

7. In the first bending step and the second bending step, the tip end surface is maintained in contact with the engaging portion, The first bending step and the second bending step are performed simultaneously. The press molding method according to claim 6.

8. In the first bending process and the second bending process, an inner surface of the inclined wall portion excluding the tip portion does not come into contact with the press forming device. The press molding method according to claim 6 or 7.

9. A press molding apparatus that performs press molding on a preform that includes a top plate portion and an inclined wall portion that is inclined in a predetermined rotation direction relative to the top plate portion, a fixing member configured to be able to sandwich and fix the top plate portion between one member and another member; a mold member having a molding side surface formed to match the target shape of the inclined wall portion; a drive device that moves the mold member toward the fixed member; Equipped with The other member has a surface facing the one member, on which a molding recess is provided that is formed to match the target shape of the curved portion of the top plate portion and the inclined wall portion. Press forming equipment.

10. A press molding apparatus that performs press molding on a preform that includes a top plate portion and an inclined wall portion that is inclined in a predetermined rotation direction relative to the top plate portion, a fixing member configured to be able to sandwich and fix the top plate portion between one member and another member; a mold member having a molding side surface formed to match the target shape of the inclined wall portion; a drive device that moves the mold member toward the fixed member; Equipped with The mold member includes an engaging portion that protrudes from the molding side surface and engages with the tip end of the inclined wall portion so that the tip end of the inclined wall portion is aligned with the molding side surface. Press forming equipment.

11. A press molding apparatus that performs press molding on a preform that includes a top plate portion and an inclined wall portion that is inclined in a predetermined rotation direction relative to the top plate portion, a fixing member configured to be able to sandwich and fix the top plate portion between one member and another member; a mold member having a molding side surface formed to match the target shape of the inclined wall portion; a drive device that moves the mold member toward the fixed member; Equipped with a protrusion protruding toward the molding side surface is formed on the one member so that a tip end surface of the inclined wall portion abuts against the protrusion during molding; Press forming equipment.

12. The other member has a surface facing the one member, on which a molding recess is provided that is formed to match the target shape of the curved portion of the top plate portion and the inclined wall portion. The press forming apparatus according to claim 10 or 11.

13. The press molding device is a drive device that moves the mold member left and right to move it toward the fixed member; a cam driver that links the vertical movement of the fixing member with the lateral movement of the mold member; Equipped with the mold member functions as a cam slider corresponding to the cam driver; The drive device moves the fixing member up and down, thereby moving the mold member left and right. The press molding method according to any one of claims 1 to 4, 6 and 7.

14. a cam driver that links the vertical movement of the fixing member with the horizontal movement of the mold member; the mold member functions as a cam slider corresponding to the cam driver; The drive device moves the fixed member up and down, thereby moving the mold member left and right to move it toward the fixed member. The press forming apparatus according to any one of claims 9 to 11.

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