Press molding apparatus and press molding method

Abstract

To provide a press molding apparatus and a press molding method capable of further suppressing sagging of an irregular shape part of a molding during punching of the molding by suppressing flowing of a material to be machined to the tip side of a projection and a corner including in the irregular shape part of the molding.SOLUTION: A press molding apparatus 100 comprises: first and second molding take-out members 1 and 2 that hold a material Pm to be machined; and a first machined material pressing member 4. The press molding apparatus 100 comprises a second machined material pressing member 3 that includes a one-side irregular shape forming unit 31 which forms an irregular shape of a molding Ga. The one-side irregular shape forming unit 31 includes a one-side upsetting projected surface 311a provided at a position where it projects to the first machined material pressing member 4 in a thickness direction to perform upsetting on the surface 31a of the first machined material pressing member 4 of the one-side irregular shape forming unit 31.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a press-molding apparatus and a press-molding method, and more particularly to a press-molding apparatus and a press-molding method for molding a molded product having an irregular shape including a protrusion or an edge. [Background technology]

[0002] 2. Description of the Related Art Conventionally, press molding apparatuses for molding molded products having irregular shapes including protrusions or corners are known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses an element manufacturing device (press molding device) that molds an element (molded product) having an irregular shape including corners. This element manufacturing device is a device that manufactures elements by punching out a metal strip-shaped material (workpiece) that is fed out.

[0004] The manufacturing device for an element in the above-mentioned Patent Document 1 includes a punch, an ejector, a sheet presser, and a die. The punch is a member that presses the strip-shaped material from one side in the thickness direction. The ejector is a member that presses the strip-shaped material from the other side in the thickness direction. The punch and the ejector face each other in the thickness direction of the strip-shaped material. The sheet presser and the die are each a member that presses the strip-shaped material. The sheet presser is disposed to the side of the punch. The die is disposed to the side of the ejector. The sheet presser and the die face each other in the thickness direction.

[0005] The element manufacturing device of the above-mentioned Patent Document 1 is configured to hold a strip-shaped material with a punch and an ejector, and to have a die bite into a portion of the strip-shaped material that corresponds to the slot portion of the element while the strip-shaped member is held down by a plate holder, so that the die is swaged in. Here, the slot portion has a groove shape formed by recessing the outer surface of the element inward.

[0006] The element manufacturing apparatus of the above-mentioned Patent Document 1 is configured to punch out a molded product from a strip-shaped material by holding the strip-shaped material with a punch and an ejector, pressing the strip-shaped material from one side in the thickness direction with a plate clamp, and moving a die from one side in the thickness direction to the other.

[0007] Here, in the manufacturing device for elements of the above-mentioned Patent Document 1, during upsetting, the punch and ejector hold the portions adjacent to both side surfaces and the bottom surface of the groove-shaped slot portion even in the portion of the band-shaped material corresponding to the groove-shaped slot portion of the element (molded product). Therefore, the material of the band-shaped material, which flows by the amount of the plate holder and the die biting into it, does not flow from the portion of the band-shaped material corresponding to the groove-shaped slot portion to the portions adjacent to both side surfaces and the bottom surface of the groove-shaped slot portion due to the holding force (compression force) of the punch and ejector. This allows the material of the band-shaped material that has flowed to the periphery where the plate holder and the die are biting into to be retained, so the hydrostatic pressure of the surrounding band-shaped material where the plate holder and the die are biting into is increased. Therefore, in the manufacturing device for elements, when the die moves from one side to the other side in the thickness direction to punch out, the hydrostatic pressure of the surrounding band-shaped material where the plate holder and the die are biting into is improved, so sagging is less likely to occur in the slot portion with a corner (irregular shape) at the tip portion. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2022-100851 A Summary of the Invention [Problem to be solved by the invention]

[0009] Here, in the manufacturing device of the element of the above-mentioned Patent Document 1, when the strip-shaped material is upset, the material of the strip-shaped material, which flows by the amount of the plate clamp and the die being bitten into, is prevented from flowing from the portion of the strip-shaped material corresponding to the slot portion of the groove shape to the portions adjacent to both sides and the bottom surface of the slot portion of the groove shape by the holding (compression) by the punch and the ejector. However, when the strip-shaped material is upset, it is considered that the flowing material of the strip-shaped material flows from the portion of the strip-shaped material corresponding to the slot portion of the groove shape to the corner side of the opening end of the slot portion of the groove shape. Therefore, in the manufacturing device of the element of the above-mentioned Patent Document 1, it is desired to further suppress the sagging of the slot portion (irregularly shaped portion) of the element (molded product) when punching out the element (molded product) by suppressing the flow of the material of the workpiece to the corner side of the opening end of the slot portion of the groove shape (the tip side of the convex portion or corner included in the irregularly shaped portion of the molded product) when upsetting.

[0010] The present invention has been made to solve the problems described above, and one object of the present invention is to provide a press molding apparatus and a press molding method that can suppress the flow of material of the workpiece toward the tips of convex portions and corners contained in the irregularly shaped portions of the molded product when upsetting is performed, thereby further suppressing the occurrence of sagging in the irregularly shaped portions of the molded product when the molded product is punched out. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, a press molding apparatus in a first aspect of the present invention comprises a first molded product extraction member and a second molded product extraction member facing one side of the first molded product extraction member in the thickness direction of the workpiece for press-molding a molded product having an irregular shape including a convex portion or an angular portion, which clamp a metal plate-shaped workpiece in the thickness direction of the workpiece, a first workpiece pressing member provided on the side of the first molded product extraction member and pressing from the other side in the thickness direction, and a second workpiece pressing member including a one-side irregular shape forming portion for forming the irregular shape of the molded product, arranged facing one side of the first workpiece pressing member in the thickness direction, and punching out a molded product from the workpiece while pressing from one side in the thickness direction with the first workpiece pressing member, and the one-side irregular shape forming portion has a one-side swaging protruding surface for performing swaging, which is provided on the surface of the one-side irregular shape forming portion facing the first workpiece pressing member at a position protruding toward the first workpiece pressing member in the thickness direction.

[0012] In the press molding device according to the first aspect of the present invention, as described above, a first molded product extraction member and a second molded product extraction member are provided to clamp the workpiece. As a result, the first molded product extraction member and the second molded product extraction member clamp the workpiece, thereby clamping (compressing) the portion of the workpiece corresponding to the irregularly shaped portion. In addition, the one-side irregular shape forming portion has a one-side swaging protruding surface for performing swaging, which is provided at a position protruding toward the first workpiece pressing member side in the thickness direction among the surface of the one-side irregular shape forming portion on the first workpiece pressing member side. As a result, the swaging of the one-side swaging protruding surface can compress (increase the surface pressure) the side of the portion corresponding to the tip of the convex portion and the corner portion included in the irregularly shaped portion of the workpiece. As a result, the material of the workpiece, which flows by the amount of the one-side irregular shape forming portion that is biting into the one-side irregular shape forming portion during upsetting, can be prevented from flowing between the first molded product extraction member and the second molded product extraction member, and can also be prevented from flowing sideways from the portion corresponding to the tip of the irregular shape portion of the workpiece. In this way, the flow of the material of the workpiece is prevented by the clamping (compression) by the first molded product extraction member and the second molded product extraction member and the compression of the one-side upsetting protruding surface during upsetting, so that a closed space (material flow space) through which the material of the workpiece flows is formed in the area surrounded by the first molded product extraction member, the second molded product extraction member, and the one-side upsetting protruding surface. As a result, the material of the workpiece, which flows by the amount of the one-side irregular shape forming portion that is biting into the one-side irregular shape forming portion, can be retained in the closed space, and the lateral hydrostatic pressure of the portion corresponding to the tip of the convex portion and the corner portion included in the irregular shape portion of the molded product can be increased. Therefore, when punching a molded product from the workpiece, the workpiece around the tips of the convex portions and corners included in the irregularly shaped portion of the molded product is less likely to move with the movement of the second workpiece pressing member, so that sagging of the irregularly shaped portion of the molded product can be suppressed. As a result, by suppressing the flow of the material of the workpiece toward the tips of the convex portions and corners included in the irregularly shaped portion of the molded product during upsetting, sagging of the irregularly shaped portion of the molded product can be further suppressed during punching.

[0013] In the press molding apparatus according to the above-mentioned first aspect, the one-side irregular shape forming portion preferably has a two-step tapered shape or a step shape having a second inclined surface between a first inclined surface provided at the tip and a one-side swaging protruding surface extending along the horizontal direction, the second inclined surface having an inclination angle smaller than the inclination angle of the first inclined surface with respect to a direction perpendicular to the thickness direction.

[0014] With this configuration, during upsetting by the one-side upsetting protruding surface, the first and second inclined surfaces of the two-step tapered shape can form a material flow space, and the second inclined surface can form a gap between the workpiece and the one-side deformed shaped portion. As a result, while the material flows into the material flow space, the upward lifting force transmitted from the one-side deformed shaped portion to the first workpiece pressing member via the workpiece can be suppressed. Furthermore, the above-mentioned gap can suppress the upward lifting of the first workpiece pressing member. Furthermore, the stepped shape can form a material flow space and a gap can be formed between the workpiece and the one-side deformed shaped portion, so that while the material flows into the material flow space, the upward lifting force transmitted from the one-side deformed shaped portion to the first workpiece pressing member via the workpiece can be suppressed.

[0015] In the press molding apparatus according to the above-mentioned first aspect, the second workpiece pressing member preferably has a one-side recess recessed in the thickness direction on the side opposite to the first workpiece pressing member so that, when the workpiece is swaged, the workpiece does not come into contact with a portion of the second workpiece pressing member that is outside the one-side swaging protruding surface.

[0016] With this configuration, the one-side recess can further reduce the range of compressive stress generated in the workpiece by the upsetting of the second workpiece pressing member, and therefore it is possible to further prevent the workpiece pressing member from lifting in a direction away from the second workpiece pressing member due to the compressive stress generated in the workpiece being transmitted to the workpiece pressing member via the workpiece, thereby further preventing sagging in the molded product.

[0017] A press-molding method according to a second aspect of the present invention is a press-molding method for punching out and molding a molded product having an irregular shape including a convex portion or an angular portion while applying a back pressure to a metal plate-like workpiece in a thickness direction of the workpiece, the method including a step of clamping the workpiece between a first molded product removal member for punching out and removing the molded product and a second molded product removal member arranged opposite to one side in the thickness direction of the first molded product removal member and removing the molded product, a first workpiece pressing member arranged to the side of the first molded product removal member pressing the workpiece from the other side in the thickness direction by the back pressure, and pressing the workpiece from one side in the thickness direction of the first workpiece pressing member, the one-side deformed shape forming portion of the second workpiece pressing member disposed opposite the one-side deformed shape forming portion, which forms the deformed shape of the molded product, presses the workpiece from one side in the thickness direction to bite into it, and after the step of upsetting the workpiece, punching out the molded product from the workpiece with the second workpiece pressing member including the one-side deformed shape forming portion, wherein the upsetting step includes a step of upsetting the workpiece by a one-side upsetting protruding surface provided at a position protruding toward the first workpiece pressing member in the thickness direction on a surface of the one-side deformed shape forming portion facing the first workpiece pressing member.

[0018] In the press molding method according to the second aspect of the present invention, as described above, a step is provided in which a first molded product extraction member for punching out and extracting a molded product and a second molded product extraction member for extracting a molded product, which is disposed opposite to one side in the thickness direction of the first molded product extraction member, sandwich the workpiece. As a result, the first molded product extraction member and the second molded product extraction member sandwich the workpiece, thereby making it possible to sandwich (compress) a portion of the workpiece corresponding to the irregularly shaped portion. The upsetting step also includes a step of upsetting the workpiece by a one-side upsetting protruding surface provided at a position protruding toward the first workpiece pressing member in the thickness direction among the surface of the one-side irregularly shaped forming portion on the first workpiece pressing member side in the thickness direction. As a result, the lateral side of the portion corresponding to the tip of the convex portion and the corner portion included in the irregularly shaped portion of the workpiece can be compressed (surface pressure can be increased) by upsetting the one-side upsetting protruding surface. As a result, during the upsetting step, the material of the workpiece, which flows by the amount of the one-side irregular shape forming portion biting in, can be prevented from flowing between the first molded product extraction member and the second molded product extraction member, and can also be prevented from flowing sideways from the portion corresponding to the tip of the irregular shape portion of the workpiece. In this way, during the upsetting step, the flow of the material of the workpiece is prevented by the clamping (compression) by the first molded product extraction member and the second molded product extraction member and the compression of the one-side upsetting protruding surface, so that a closed space (material flow space) for the material of the workpiece to flow is formed in the area surrounded by the first molded product extraction member, the second molded product extraction member, and the one-side upsetting protruding surface. As a result, the material of the workpiece, which flows by the amount of the one-side irregular shape forming portion biting in, can be retained in the closed space, so that the lateral hydrostatic pressure of the portion of the workpiece corresponding to the tip of the convex portion and the corner portion included in the irregular shape portion of the molded product can be increased. Therefore, during the step of punching out the molded product from the workpiece, the workpiece around the tips of the convex and corner portions contained in the irregularly shaped portion of the molded product is less likely to move as the second workpiece pressing member moves, thereby suppressing the occurrence of sagging in the irregularly shaped portion of the molded product.As a result, a press molding method can be provided that can further suppress the occurrence of sagging in the irregularly shaped portion of the molded product in the punching step by suppressing the flow of material from the workpiece toward the tip sides of the convex portions and corners contained in the irregularly shaped portion of the molded product during the upsetting step.

[0019] The step of upsetting includes a step of upsetting the workpiece by a one-side upsetting protruding surface provided at a position protruding toward the first workpiece pressing member in the thickness direction among the surfaces of the one-side irregular shape forming portion on the workpiece pressing member side in the thickness direction. This makes it possible to relatively reduce the range of compressive stress generated in the workpiece by the upsetting of the second workpiece pressing member, and therefore it is possible to suppress the first workpiece pressing member from lifting in a direction away from the second workpiece pressing member due to the compressive stress generated in the workpiece being transmitted to the first workpiece pressing member via the workpiece. Here, if the first workpiece pressing member is lifted, the back pressure from the first workpiece pressing member is no longer applied, and the second workpiece pressing member moves toward the first workpiece pressing member, causing sagging in the molded product. In this way, by making relatively small the range of compressive stress generated in the workpiece by upsetting the second workpiece pressing member, a press molding method can be provided that can suppress the occurrence of sagging in the molded product.

[0020] In the press forming apparatus according to the first aspect, the following configuration is also possible.

[0021] (Additional note 1) In the press molding apparatus according to the above-mentioned first aspect, the one-side upsetting protruding surface is provided in a direction from the first product extraction member toward the workpiece pressing member, relative to the molded product portion where the convex portion or corner portion of the molded product of the workpiece is formed, when viewed from the first workpiece pressing member side in the thickness direction.

[0022] With this configuration, the hydrostatic pressure of the workpiece can be increased by compressing the workpiece with the one-side upsetting protruding surface, so that the material that flows from the portion of the workpiece corresponding to the convex portion or corner of the molded product in the direction from the first molded product extraction member toward the first workpiece pressing member can be retained in the closed space.

[0023] (Additional note 2) In a press molding apparatus equipped with a second workpiece pressing member including the above-mentioned two-stage taper shape or step shape, the two-stage taper shape or step shape is arranged in a direction perpendicular to the direction from the first product removal member toward the first workpiece pressing member, relative to the molded product portion where the convex portion or corner portion of the molded product of the workpiece is formed, when viewed from the first workpiece pressing member side in the thickness direction.

[0024] By configuring in this manner, a material flow space can be formed by the two-stage tapered or stepped shape, and a gap can be formed between the workpiece and the one-side deformed shaped forming portion.Therefore, while allowing the material to flow into the material flow space, the upward lifting force transmitted from the one-side deformed shaped forming portion via the workpiece to the first workpiece pressing member can be suppressed.

[0025] (Additional note 3) In the press forming apparatus according to the first aspect described above, the second workpiece pressing member is a die including a die-side swaging protruding surface as the one-side swaging protruding surface.

[0026] With this configuration, the workpiece can be upset using the die, so that upsetting of the workpiece can be easily controlled.

[0027] (Additional note 4) In this case, the first workpiece pressing member further includes an other-side swaging protruding surface provided on the other side in the thickness direction of the die side swaging protruding surface of the die, and an other-side recess recessed in the thickness direction on the side opposite the die side so that the workpiece and the portion outer than the other-side swaging protruding surface of the first workpiece pressing member do not come into contact when the workpiece is swaged.

[0028] With this configuration, the contact area between the first workpiece pressing member and the workpiece can be reduced when the workpiece is upset by the die-side upsetting protruding surface, thereby reducing the range of compressive stress transmitted to the first workpiece pressing member via the workpiece, thereby more effectively preventing the first workpiece pressing member from lifting in a direction away from the die.

[0029] (Additional note 5) In the press molding apparatus according to the first aspect described above, the molded product includes at least one of a gear and an element constituting a transmission belt that is attached between a pair of pulleys of a continuously variable transmission by being annularly arranged on an endless ring.

[0030] With this configuration, it is possible to suppress sagging at irregular shaped portions such as external or internal teeth as convex portions of the gear during press molding of the gear, and also to suppress sagging at irregular shaped portions such as corners of the element during press molding of the element.

[0031] In the press molding method according to the second aspect, the following configuration is also possible.

[0032] (Additional note 6) In the press molding method according to the above-mentioned second aspect, the second workpiece pressing member is arranged to the side of the second molded product extraction member in a direction perpendicular to the thickness direction, and the step of performing upsetting includes a step of causing a portion of the workpiece to flow into the material flow space on the second molded product extraction member side relative to the one-side upsetting protruding surface by biting into the one-side irregularly shaped forming portion in a direction perpendicular to the thickness direction.

[0033] With this configuration, by flowing a part of the workpiece in the material flow space, the material can be retained in the closed space, and the hydrostatic pressure around the tips of the convex parts and corners included in the irregularly shaped part of the molded product can be increased. Therefore, the force applied from the second workpiece pressing member can be made less likely to escape, so that shear stress can be generated in the part of the workpiece corresponding to the irregularly shaped part at an early stage of the punching step by the second workpiece pressing member. As a result, shearing starts early in the part of the workpiece corresponding to the irregularly shaped part, so that the workpiece can be punched in a shape that conforms to the irregularly shaped part of the molded product while suppressing the occurrence of sagging.

[0034] (Additional note 7) In the press molding method according to the above-mentioned second aspect, before the step of clamping the workpiece between the first molded product extraction member and the second molded product extraction member, the press molding method further includes a step of performing a bending process using the first workpiece pressing member and the second molded product extraction member to bend the workpiece at the boundary portion between the first workpiece pressing member and the second molded product extraction member in the thickness direction toward the second workpiece pressing member.

[0035] With this configuration, by performing the bending process, the workpiece at the boundary between the first molded product extraction member and the second molded product extraction member is bent toward the second workpiece pressing member, and the material of the workpiece can be made to flow into the closed space (material flow space) for allowing the material of the workpiece to flow by the amount of the workpiece bent toward the second workpiece pressing member.Therefore, when the second workpiece pressing member moves toward the workpiece pressing member to punch out the molded product, even if the workpiece at the boundary moves together with the second workpiece pressing member, sagging can be prevented from occurring at the end of the molded product. [Brief description of the drawings]

[0036] [Figure 1] 1 is a schematic cross-sectional view of a press-molding apparatus to which a press-molding method according to a first embodiment is applied. [Diagram 2] FIG. 2 is a plan view showing a sector gear formed by the press forming apparatus of the first embodiment. [Diagram 3] FIG. 13 is a schematic diagram showing a state in which sagging has occurred in the external teeth of a sector gear, which is a comparative molded product. [Figure 4] FIG. 2 is a plan view of a die used in the press-molding method of the press-molding apparatus of the first embodiment. [Diagram 5] FIG. 2 is a perspective view of a die used in the press-molding method of the press-molding apparatus of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 5 is an enlarged view of the Zm1 portion of FIG. [Figure 8] FIG. 2 is a plan view of a stripper used in the press-molding method of the press-molding apparatus of the first embodiment. [Figure 9] FIG. 2 is a perspective view of a stripper used in the press-molding method of the press-molding apparatus of the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view taken along line XX in FIG. [Figure 11] FIG. 9 is an enlarged view of the Zm2 portion of FIG. 8. [Figure 12] 2 is a flowchart showing a press molding method according to the first embodiment. [Figure 13] FIG. 2 is a schematic diagram showing an upsetting step of the press molding method according to the first embodiment. [Figure 14] FIG. 1 is a schematic diagram showing the width of the die-side protruding surface for swaging and the distribution of compressive stress in the first comparative example. [Figure 15] FIG. 11 is a schematic diagram showing the width of the die-side swaging protruding surface and the distribution of compressive stress in the second comparative example. [Figure 16] FIG. 2 is a schematic diagram showing a punching process of the press molding method according to the first embodiment. [Figure 17] FIG. 4 is a schematic cross-sectional view of a press-molding apparatus to which a press-molding method according to a second embodiment is applied. [Figure 18] 6 is a flowchart showing a press molding method according to a second embodiment. [Figure 19] FIG. 11 is a schematic diagram showing an upsetting step of the press molding method according to the second embodiment. [Figure 20]10 is a flowchart showing a press molding method according to a third embodiment. [Figure 21] FIG. 11 is a schematic diagram showing a bending step of the press forming method according to the third embodiment. [Figure 22] FIG. 13 is a side view showing an element which is a molded product used in the press molding method of a first modified example of the first to third embodiments. [Diagram 23] FIG. 4 is a plan view of a die used in the press-molding method of a first modified example of the first to third embodiments. [Figure 24] FIG. 13 is a plan view showing a corner of a molded product used in a press molding method according to a second modified example of the first to third embodiments. [Diagram 25] 9 is an enlarged view corresponding to a portion Zm2 in FIG. 8 of a stripper used in a press-forming method for a press-forming apparatus in a third modified example of the first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0038] [First embodiment] The configuration of a press-forming apparatus 100 according to the first embodiment will be described with reference to FIGS.

[0039] As shown in Fig. 1, the press forming apparatus 100 is configured to press-form a sector gear Ge (see Fig. 2) as a formed product from a metal plate-shaped workpiece Pm. In the following description, the formed product will be described as a sector gear Ge, but formed products other than the sector gear Ge are also possible.

[0040] The press molding apparatus 100 includes a punch 1, a knockout 2, a die 3, and a stripper 4. Each of the punch 1, the knockout 2, the die 3, and the stripper 4 is a metal mold. The punch 1 is an example of a "first molded product extraction member" in the claims. The knockout 2 is an example of a "second molded product extraction member" in the claims. The die 3 is an example of a "second workpiece pressing member" in the claims. The stripper 4 is an example of a "first workpiece pressing member" in the claims.

[0041] Here, the vertical direction is the Z direction, the upward direction is the Z1 direction, and the downward direction is the Z2 direction. The horizontal directions that are perpendicular to each other are the X direction and the Y direction. One of the X directions is the X1 direction, and the other is the X2 direction. One of the Y directions is the Y1 direction, and the other is the Y2 direction. The Z direction is an example of a "thickness direction" in the claims. The Z1 direction is also an example of a "one side of the thickness direction" in the claims. The Z2 direction is also an example of a "other side of the thickness direction" in the claims.

[0042] The punch 1 is a member for punching out the sector gear Ge. The punch 1 is disposed inside the through hole 4a of the stripper 4. The punch 1 has a shape corresponding to the sector gear Ge. The punch 1 is fixed.

[0043] The knockout 2 is a member for removing the molded product. The knockout 2 is disposed inside the through hole 3a of the die 3. The knockout 2 has a shape corresponding to the sector gear Ge. The knockout 2 is configured to move in each of the Z1 direction and the Z2 direction by hydraulic pressure supplied from a hydraulic device (not shown).

[0044] The punch 1 is disposed opposite the knockout 2 on the Z1 direction side. The knockout 2 is disposed opposite the punch 1 on the Z2 direction side. In addition, as the knockout 2 moves in the Z1 direction, the punch 1 and the knockout 2 sandwich the workpiece Pm by back pressure based on hydraulic pressure supplied from a hydraulic device. In addition, as the knockout 2 moves in the Z2 direction, the sandwiching between the punch 1 and the knockout 2 is released.

[0045] The die 3 is a member for punching out a sector gear Ge (molded product) from a workpiece Pm. The die 3 has a through hole 3a having a shape corresponding to the sector gear Ge. The through hole 3a penetrates the die 3 in the Z direction. The die 3 is disposed on the side (outside) of the knockout 2 in the XY direction (horizontal direction). The die 3 is disposed facing the stripper 4 on the Z2 direction side. The die 3 is configured to move in each of the Z1 direction and the Z2 direction by a driving force from a driving source (e.g., a motor) not shown.

[0046] The stripper 4 is a member for applying a compressive force to the workpiece Pm. The stripper 4 has a through hole 4a having a shape corresponding to the sector gear Ge. The through hole 4a penetrates the stripper 4 in the Z direction. The stripper 4 is disposed on the side (outside) of the punch 1 in the XY direction (horizontal direction). The stripper 4 is disposed facing the Z1 direction side of the die 3. The stripper 4 is configured to move in each of the Z1 direction and the Z2 direction by hydraulic pressure supplied from a hydraulic device (not shown).

[0047] The stripper 4 moves in the Z2 direction and the die 3 moves in the Z1 direction, so that the stripper 4 and the die 3 sandwich the workpiece Pm. The stripper 4 is pressed by the back pressure based on the hydraulic pressure supplied from the hydraulic device, while the die 3 moves in the Z1 direction based on the driving force from the drive source, and the stripper 4 moves in the Z1 direction to punch the sector gear Ge out of the workpiece Pm. At this time, the punch 1 and the knockout 2 sandwich the workpiece Pm by the back pressure based on the hydraulic pressure supplied from the hydraulic device. After punching out the sector gear Ge, the stripper 4 moves in the Z2 direction to return to its original position, and the die 3 moves in the Z2 direction to return to its original position.

[0048] In this way, the press forming apparatus 100 is configured to form a sector gear Ge having an irregular shape including external teeth Ge1 (see FIG. 2) by applying back pressure in the Z direction to the metal plate-like workpiece Pm and punching it from the Z2 direction side with the die 3. In the sector gear Ge, the portion other than the external teeth Ge1 is a main body portion Ge2 (see FIG. 2). The external teeth Ge1 are an example of the "irregular shape including a protrusion" in the claims.

[0049] (Detailed configuration of the die and stripper) Each of the die 3 and the stripper 4 of the first embodiment has a configuration for suppressing sagging Ged of the external teeth Ge1 that occurs when punching a sector gear Ge (a comparative molded product) having an irregularly shaped portion including the external teeth Ge1, as shown in Fig. 3. The sagging Ged is a rounded shape formed on the external teeth Ge1 along the punching direction (Z1 direction) of the die 3.

[0050] (Detailed die configuration) Specifically, as shown in Figures 4 and 5, the die 3 includes a die side irregular shape forming portion 31 and a die side recess 32. The die side irregular shape forming portion 31 is an example of a "one side irregular shape forming portion" in the claims. The die side recess 32 is an example of a "one side recess" in the claims.

[0051] The die side irregular shape forming portion 31 is configured to form the external teeth Ge1 of the sector gear Ge (irregular shape portion of the molded product). That is, the die side irregular shape forming portion 31 has a shape that matches the external teeth Ge1 of the sector gear Ge when viewed from the Z1 direction side.

[0052] As shown in FIG. 6, the die side irregular shape forming part 31 has a surface 31a on the Z1 direction side of the die side irregular shape forming part 31. The surface 31a is provided with a die side swaging protruding surface 311a, an inclined surface 312a, and an inclined surface 313a. The die side swaging protruding surface 311a is an example of a "one side swaging protruding surface" in the claims. The inclined surface 312a is an example of a "first inclined surface" in the claims. The inclined surface 313a is an example of a "second inclined surface" in the claims.

[0053] The die side protruding surface 311a for swaging is a surface for performing swaging. The die side protruding surface 311a for swaging is provided at a position protruding toward the Z1 direction side (the stripper 4 side in the thickness direction) of the surface 31a. The die side protruding surface 311a for swaging is the surface of the surface 31a disposed closest to the X2 direction side. The die side protruding surface 311a for swaging is a surface extending along the XY direction (horizontal direction).

[0054] The inclined surface 312a is a surface for forming the material flow space 33 (see FIG. 13). The inclined surface 312a is a surface of a chamfered portion provided at the tip of the die side irregular shape forming portion 31. The inclined surface 312a is a surface arranged closest to the X1 direction side among the surfaces 31a. The inclined surface 312a is a surface inclined at an inclination angle θ1 toward the Z1 direction side with respect to the XY direction (horizontal direction). The inclined surface 313a is a surface for forming the material flow space 33 (see FIG. 13) and is a surface for forming a gap between the workpiece Pm and the die side irregular shape forming portion 31. The inclined surface 313a is a surface provided between the inclined surface 312a and the die side swaging protruding surface 311a. The inclined surface 313a is provided adjacent to the die side swaging protruding surface 311a on the X1 direction side. The inclined surface 313a is inclined at an inclination angle θ2 toward the Z1 direction with respect to the XY direction (horizontal direction). The inclination angle θ2 of the inclined surface 313a is smaller than the inclination angle θ1 of the inclined surface 312a.

[0055] In this way, a tapered shape having an inclined surface 312a is provided in a recessed portion (Pr1 portion in FIG. 7) corresponding to the crest portion of the external tooth Ge1 of the die side irregular shape forming portion 31. Also, a two-stage tapered shape having an inclined surface 312a and an inclined surface 313a is provided in a protruding portion (Pr2 portion in FIG. 7) corresponding to the valley portion of the external tooth Ge1 of the die side irregular shape forming portion 31.

[0056] 7, when the workpiece Pm is being upset, the two-stage taper shape is provided on each of the Y1 and Y2 sides of the molded product portion Pm1 where the external teeth Ge1 of the sector gear Ge of the workpiece Pm are formed, as viewed from the Z1 side. Also, when the workpiece Pm is being upset, the die-side upsetting protruding surface 311a is provided on the X2 side of the molded product portion Pm1 where the external teeth Ge1 of the sector gear Ge of the workpiece Pm are formed, as viewed from the Z1 side.

[0057] 6 and 7, the die side recess 32 is a recess recessed in the Z2 direction so that the workpiece Pm does not come into contact with a portion of the die 3 on the X2 side of the die side protruding surface 311a for swaging when the workpiece Pm is swaged. The die side recess 32 has a stepped shape recessed in the Z2 direction from the end of the die side protruding surface 311a for swaging on the X2 side. The die side recess 32 is provided not only at the end of the die side protruding surface 311a for swaging on the X2 side, but also in a portion corresponding to the main body Ge2 of the sector gear Ge (see FIG. 2).

[0058] (Detailed configuration of the stripper) Specifically, as shown in FIGS. 8 and 9, the stripper 4 includes a stripper-side irregular shape forming portion 41 and a stripper-side recess .

[0059] The stripper side irregular shape forming portion 41 is configured to form the external teeth Ge1 (irregular shape of the molded product) of the sector gear Ge. That is, the stripper side irregular shape forming portion 41 has a shape that matches the external teeth Ge1 of the sector gear Ge when viewed from the Z2 direction side.

[0060] 10, the stripper side deformed shape forming portion 41 has a surface 41a on the Z2 direction side of the stripper side deformed shape forming portion 41. The surface 41a is provided with a stripper side swaging protruding surface 411a and an inclined surface 412a.

[0061] The stripper side swaging protruding surface 411a is provided to change the material flow of the workpiece Pm and the hydrostatic pressure state of the workpiece Pm by the die side swaging protruding surface 311a. The stripper side swaging protruding surface 411a is provided at a position protruding toward the Z2 direction side (toward the die 3 in the thickness direction) of the surface 41a. The stripper side swaging protruding surface 411a is a surface disposed on the X2 direction side of the surface 41a. The stripper side swaging protruding surface 411a is a surface extending along the XY direction (horizontal direction). The stripper side swaging protruding surface 411a is provided on the Z1 direction side of the die side swaging protruding surface 311a of the die 3.

[0062] The inclined surface 412a is a surface for forming a gap between the workpiece Pm and the die-side irregular shaped forming portion 31. The inclined surface 412a is a surface arranged on the X1 direction side of the surface 41a. The inclined surface 412a is a surface inclined at an inclination angle θ3 toward the Z1 direction side with respect to the XY direction (horizontal direction).

[0063] In this manner, a portion (Pr3 portion in FIG. 11) protruding in correspondence with the valley portion of the external tooth Ge1 of the stripper-side deformed portion 41 is provided with a tapered shape having an inclined surface 412a.

[0064] 11, when the workpiece Pm is being upset, the taper shapes are provided on the Y1 and Y2 sides of the molded product portion Pm1 where the external teeth Ge1 of the sector gear Ge of the workpiece Pm are formed, as viewed from the Z1 side. Also, when the workpiece Pm is being upset, the stripper-side upsetting protruding surface 411a is provided on the X2 side of the molded product portion Pm1 where the external teeth Ge1 of the sector gear Ge of the workpiece Pm are formed, as viewed from the Z1 side.

[0065] 10 and 11, the stripper side recess 42 is a recess recessed in the Z1 direction so that the workpiece Pm does not come into contact with a portion of the stripper 4 on the X2 side of the stripper side swaging protruding surface 411a when the workpiece Pm is swaged. The stripper side recess 42 has a stepped shape recessed in the Z1 direction from the end of the stripper side swaging protruding surface 411a on the X2 side. The stripper side recess 42 is provided not only at the end of the stripper side swaging protruding surface 411a on the X2 side, but also in a portion corresponding to the main body Ge2 of the sector gear Ge (see FIG. 2).

[0066] (Press molding method) 12 to 16, a press-forming method using the above-mentioned press-forming apparatus 100 will be described. As described above, the sector gear Ge will be shown below as an example of a formed product.

[0067] In step S1, an upsetting process is performed. In step S1, the punch 1 and the knockout 2 arranged opposite the punch 1 on the Z2 direction side clamp the workpiece Pm by back pressure. In step S1, while the punch 1 and the knockout 2 clamp the workpiece Pm by back pressure, the stripper 4 presses or presses and bites into the workpiece Pm from the Z1 direction side by back pressure, and the die-side irregular shape forming portion 31 of the die 3 arranged opposite the stripper 4 on the Z2 direction side presses and bites into the workpiece Pm from the Z2 direction side to perform upsetting (see FIG. 13).

[0068] Here, the step S1 of performing upsetting in the first embodiment includes a step of performing upsetting on the workpiece Pm by the die side upsetting protruding surface 311a of the die side irregular shape forming portion 31 in the Z direction. That is, the step S1 of performing upsetting includes a step of performing upsetting on the workpiece Pm by only the die side upsetting protruding surface 311a or by both the stripper side upsetting protruding surface 411a and the die side upsetting protruding surface 311a in the Z direction. Specifically, when it is necessary to change the material flow of the workpiece Pm and the hydrostatic pressure state of the workpiece Pm by the die side upsetting protruding surface 311a, upsetting is performed by the stripper side upsetting protruding surface 411a, but when it is not necessary, upsetting is not performed by the stripper side upsetting protruding surface 411a. In addition, in FIG. 13, upsetting of the workpiece Pm is performed by the stripper side upsetting protruding surface 411a and the die side upsetting protruding surface 311a.

[0069] Here, as shown in Fig. 13, by the die side swaging protrusion surface 311a and the stripper side swaging protrusion surface 411a swaging, a compression force Pr1 is applied from the die side swaging protrusion surface 311a to the periphery of the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge, and a compression force Pr2 is applied from the stripper side swaging protrusion surface 411a. That is, the surface pressure around the portion of the workpiece Pm corresponding to the tip of the external teeth Ge1 of the sector gear Ge can be increased. This makes it possible to suppress the flow FL of the material in the X2 direction from the portion of the workpiece Pm corresponding to the tip of the external teeth Ge1 of the sector gear Ge.

[0070] In addition, by being clamped between the punch 1 and the knockout 2, the flow of material from a portion of the workpiece Pm adjacent to the portion corresponding to the external teeth Ge1 of the sector gear Ge of the workpiece Pm to the external teeth Ge1 portion of the sector gear Ge of the workpiece Pm is suppressed in each of the Y1 direction and the Y2 direction. By being clamped between the punch 1 and the knockout 2, the flow of material to a portion of the workpiece Pm corresponding to the tip of the external teeth Ge1 of the sector gear Ge of the sector gear Ge is suppressed in the X1 direction.

[0071] As a result, the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge and its surroundings are compressed and blocked by the punch 1, knockout 2, die side swaging protruding surface 311a, and stripper side swaging protruding surface 411a, respectively, so that the flow of the material that flows during swaging can be suppressed. That is, due to the blocking state caused by the clamping (compression) of the punch 1 and knockout 2 and the compression of the die side swaging protruding surface 311a, a blocked space that suppresses the flow of the material of the workpiece Pm is formed in the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge and its surroundings. As a result, in step S2, which is the punch forming process, it is possible to suppress the occurrence of sagging in the portion of the workpiece Pm corresponding to the tip of the external teeth Ge1 of the sector gear Ge.

[0072] In order to achieve this closed state and a predetermined hydrostatic pressure (to achieve a compressed state in the thickness direction of the workpiece Pm (Z direction)), the width of each of the die side swaging protruding surface 311a and the stripper side swaging protruding surface 411a in the X direction has a predetermined length.

[0073] As shown in the first comparative example in FIG. 14, when the die-side swaging protruding surface Su1 has a relatively large width Wi1, the range of compressive stress becomes large, and the stripper 4 is lifted in the Z1 direction, so that the surface pressure around the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge cannot be appropriately increased. In addition, when the range of compressive stress is large, sagging occurs due to the material flow during swaging. Therefore, sagging occurs in the circled portion in FIG. 14. In addition, as shown in the second comparative example in FIG. 15, when the die-side swaging protruding surface Su2 has a relatively small width Wi1, the range of compressive stress is small, so that the surface pressure around the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge cannot be appropriately increased. Therefore, sagging occurs in the circled portion in FIG. 15 during punch forming.

[0074] As shown in Figure 13, step S1 of upsetting includes a step of causing a portion of the workpiece Pm to flow into the material flow space 33 on the X1 direction side of the die side upsetting protrusion surface 311a by biting into the die side irregular shape forming portion 31 in the XY direction (horizontal direction) perpendicular to the Z direction.

[0075] That is, in the upsetting step S1, the workpiece Pm is upset by the die side deformed shape forming part 31 having a two-stage tapered shape with an inclined surface 312a and an inclined surface 313a. As a result, the material flow space 33 is formed by the two-stage tapered shape, so that the material around the part of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge flows along the FL1 direction into the material flow space 33 by the amount of the intrusion of the die side deformed shape forming part 31. As a result, the material can be made to flow to the part of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge.

[0076] In step S1 where the upsetting is performed, since the material flow space 43 is formed by the tapered shape having the inclined surface 412a, the material around the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge flows along the FL2 direction into the material flow space 43 by the amount of the stripper side deformed shape forming portion 41 being bitten in. As a result, the material can be made to flow to the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge.

[0077] In addition, the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge and its surroundings are compressed and blocked by each of the punch 1, knockout 2, die side swaging protruding surface 311a and stripper side swaging protruding surface 411a, so that the flowed material can be securely retained in the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge.

[0078] 13, the upsetting step S1 includes a step of upsetting the workpiece Pm by a die 3 having a die side recess 32 so that the workpiece Pm does not come into contact with a portion of the die 3 that is closer to the X2 direction (outside) than the die side upsetting protruding surface 311a. The upsetting step S1 also includes a step of upsetting the workpiece Pm by a stripper 4 having a stripper side recess 42 so that the workpiece Pm does not come into contact with a portion of the stripper 4 that is closer to the X2 direction (outside) than the stripper side upsetting protruding surface 411a.

[0079] In step S1, the die-side swaging protrusion surface 311a and the stripper-side swaging protrusion surface 411a are swaged to increase the surface pressure around the portion of the workpiece Pm that corresponds to the tip of the external teeth Ge1 of the sector gear Ge, and the die 3 and the stripper 4 increase the surface pressure of the portion of the workpiece Pm that corresponds to the main body Ge2 (see FIG. 2) of the sector gear Ge. In this way, step S1 is a process of increasing the hydrostatic pressure of each of the portion of the workpiece Pm that corresponds to the tip of the external teeth Ge1 of the sector gear Ge and the portion of the workpiece Pm that corresponds to the main body Ge2 of the sector gear Ge.

[0080] In step S2, a punch forming process is performed (see FIG. 12). That is, as shown in FIG. 16, step S2 is a step of punching out a sector gear Ge (molded product) from the workpiece Pm after step S1 of upsetting the workpiece Pm. Specifically, step S2 of punch forming is a step of punching out a molded product from the workpiece Pm by moving the die 3 in the Z1 direction while the punch 1 and knockout 2 clamp the workpiece Pm by back pressure and the stripper 4 presses the workpiece Pm from the Z1 direction side by back pressure after the step of upsetting the workpiece Pm.

[0081] At this time, as described above, the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge and its surroundings are compressed and blocked by the punch 1, the knockout 2, the die side swaging protruding surface 311a and the stripper side swaging protruding surface 411a, and the flowed material is retained around the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge. Therefore, when the die 3 moves in the Z1 direction, the material is unlikely to escape from the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge, and sagging is unlikely to occur because the hydrostatic pressure in the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge is increased.

[0082] Therefore, when the die 3 starts to move in the Z1 direction, shear stress Shs is generated in the portion of the workpiece Pm that corresponds to the external teeth Ge1 of the sector gear Ge, and the workpiece Pm can be punched in a shape that follows the external teeth Ge1 of the sector gear Ge while suppressing the occurrence of sagging. If the material is not in a blocked state and does not remain, when the die 3 starts to move in the Z1 direction, shear stress Shs is not generated in the portion of the workpiece Pm that corresponds to the external teeth Ge1 of the sector gear Ge, and sagging along the movement of the die 3 in the Z1 direction occurs.

[0083] After step S2, the press-forming method ends. The press-forming method including steps S1 and S2 is performed as many times as the number of sector gears Ge to be produced.

[0084] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0085] In the first embodiment, as described above, the press forming apparatus 100 includes the punch 1 and the knockout 2 that sandwich the workpiece Pm. As a result, the punch 1 and the knockout 2 sandwich the workpiece Pm, thereby making it possible to sandwich (compress) the external teeth Ge1 (protruding portion: irregularly shaped portion) of the workpiece Pm. In addition, the die side irregular shape forming part 31 has a die side swaging protruding surface 311a that performs upsetting, which is provided at a position protruding toward the stripper 4 side in the Z direction among the surface 31a on the stripper 4 side of the die side irregular shape forming part 31. As a result, the side of the portion corresponding to the tip of the external teeth Ge1 (protruding portion: irregularly shaped portion) of the workpiece Pm can be compressed (surface pressure can be increased) by upsetting the die side swaging protruding surface 311a. As a result, the material of the workpiece Pm, which flows by the amount of the die-side irregular shape forming portion 31 biting into it during upsetting, can be prevented from flowing between the punch 1 and the knockout 2, and can also be prevented from flowing sideways from the portion corresponding to the tip of the external teeth Ge1 (convex portion: irregular shape portion) of the workpiece Pm. In this way, the flow of the material of the workpiece Pm is prevented by the clamping (compression) by the punch 1 and the knockout 2 and the compression of the die-side upsetting protruding surface 311a during upsetting, so that a closed space (material flow space 33) for allowing the material of the workpiece Pm to flow is formed in the area surrounded by the punch 1, the knockout 2, and the die-side upsetting protruding surface 311a. As a result, the material of the workpiece Pm, which flows by the amount of the die-side irregular shape forming portion 31 biting into it, can be retained in the closed space, so that the lateral hydrostatic pressure of the portion of the workpiece Pm corresponding to the tip of the external teeth Ge1 (convex portion: irregular shape portion) of the sector gear Ge can be increased. Therefore, when the sector gear Ge is punched out of the workpiece Pm, the workpiece Pm around the tip of the external teeth Ge1 (protrusion: irregularly shaped portion) of the sector gear Ge is less likely to move with the movement of the die 3, so that it is possible to suppress the occurrence of sagging of the external teeth Ge1 (protrusion: irregularly shaped portion) of the sector gear Ge. As a result, by suppressing the flow of the material of the workpiece Pm toward the tip side of the external teeth Ge1 (protrusion: irregularly shaped portion) of the sector gear Ge when upsetting, it is possible to further suppress the occurrence of sagging of the external teeth Ge1 (protrusion: irregularly shaped portion) of the sector gear Ge when punching out the sector gear Ge.

[0086] In the first embodiment, as described above, the press molding apparatus 100 has a two-stage tapered shape having an inclined surface 313a with an inclination angle θ2 smaller than the inclination angle θ1 of the inclined surface 312a in a direction perpendicular to the Z direction (thickness direction) between the inclined surface 312a provided at the tip of the die side deformed shape forming portion 31 and the die side swaging protruding surface 311a extending along the horizontal direction. As a result, the material flow space 33 can be formed by the inclined surface 312a and the inclined surface 313a of the two-stage tapered shape, and the inclined surface 313a can form a gap between the workpiece Pm and the die side deformed shape forming portion 31. As a result, while the material is caused to flow in the material flow space 33, the upward lifting force transmitted from the die side deformed shape forming portion 31 to the stripper 4 via the workpiece Pm can be suppressed. In addition, the above gap can suppress the upward lifting of the stripper 4.

[0087] In the first embodiment, as described above, the press molding apparatus 100 has the die-side recess 32 recessed in the Z direction (thickness direction) on the opposite side to the stripper 4 side so that the workpiece Pm does not come into contact with the portion of the die 3 that is outside the die-side swaging protruding surface 311a when the workpiece Pm is swaged. This makes it possible to further reduce the range of compressive stress generated in the workpiece Pm by the swaging of the die 3 by the die-side recess 32, and therefore to further suppress the stripper 4 from lifting in the direction away from the die 3 due to the compressive stress generated in the workpiece Pm being transmitted to the stripper 4 via the workpiece Pm. As a result, it is possible to further suppress the occurrence of sagging in the sector gear Ge (molded product).

[0088] In the first embodiment, as described above, the press forming apparatus 100 includes a step S1 in which the punch 1 for punching out and extracting the sector gear Ge (molded product) and the knockout 2 arranged opposite to the Z2 direction (one side) of the punch 1 in the Z direction (thickness direction) and extracting the sector gear Ge (molded product) clamp the workpiece Pm. As a result, the punch 1 and the knockout 2 clamp the workpiece Pm, thereby clamping (compressing) the external teeth Ge1 (protruding portion: irregular shape portion) of the workpiece Pm. In addition, the step S1 of upsetting includes a step of upsetting the workpiece Pm by the die side upsetting protruding surface 311a provided at a position protruding toward the stripper 4 side in the Z direction among the surface 31a on the stripper 4 side of the die side irregular shape forming part 31 in the Z direction. As a result, the swaging of the die side swaging protruding surface 311a can compress (increase surface pressure) the side of the portion corresponding to the tip of the external tooth Ge1 (convex portion: irregular shape portion) of the workpiece Pm. As a result, during the swaging step S1, the material of the workpiece Pm, which flows by the amount of the die side irregular shape forming portion 31 biting into it, can be suppressed from flowing between the punch 1 and the knockout 2, and the flow of the material of the workpiece Pm from the portion corresponding to the tip of the external tooth Ge1 (convex portion: irregular shape portion) can be suppressed. In this way, during the swaging step S1, the flow of the material of the workpiece Pm is suppressed by the clamping (compression) by the punch 1 and the knockout 2 and the compression of the die side swaging protruding surface 311a, so that a closed space (material flow space 33) for flowing the material of the workpiece Pm is formed in the area surrounded by the punch 1, the knockout 2, and the die side swaging protruding surface 311a. This allows the material of the workpiece Pm, which flows by the amount of the die-side irregular shape forming portion 31 biting into it, to remain in the closed space, thereby increasing the lateral hydrostatic pressure of the portion of the workpiece Pm that corresponds to the tip of the external teeth Ge1 (protrusion: irregular shape portion) of the sector gear Ge. Therefore, during step S2 of punching the sector gear Ge from the workpiece Pm, the workpiece Pm around the tip of the external teeth Ge1 (protrusion: irregular shape portion) of the sector gear Ge becomes less likely to move with the movement of the die 3, so that sagging of the external teeth Ge1 (protrusion: irregular shape portion) of the sector gear Ge can be suppressed.As a result, by suppressing the flow of material of the workpiece Pm toward the tip side of the external teeth Ge1 (convex portion: irregularly shaped portion) of the sector gear Ge during the upsetting step S1, it is possible to provide a press molding method that can further suppress the occurrence of sagging of the external teeth Ge1 (convex portion: irregularly shaped portion) of the sector gear Ge during the punching step S2.

[0089] In the first embodiment, as described above, the step S1 of performing upsetting includes a step S1 of performing upsetting on the workpiece Pm by the die-side upsetting protruding surface 311a provided at a position protruding toward the stripper 4 side in the Z direction (thickness direction) among the surface 31a on the stripper 4 side of the die-side irregular shape forming part 31 in the Z direction (thickness direction). This makes it possible to relatively reduce the range of compressive stress generated in the workpiece Pm by upsetting the die 3, and therefore it is possible to suppress the stripper 4 from lifting in the direction away from the die 3 (Z1 direction) due to the compressive stress generated in the workpiece Pm being transmitted to the stripper 4 through the workpiece Pm. Here, if the stripper 4 is lifted, the back pressure from the stripper 4 is no longer applied, and sagging occurs in the sector gear Ge (molded product) due to the die 3 moving toward the stripper 4 side. In this way, by making the range of compressive stress generated in the workpiece Pm by upsetting the die 3 relatively small, it is possible to suppress the occurrence of sagging in the sector gear Ge (molded product).

[0090] [Second embodiment] The configuration of a press molding apparatus 500 according to the second embodiment will be described with reference to Fig. 17 to Fig. 19. In the second embodiment, the press molding apparatus 500 includes a die 503 having a stepped shape. Note that in the second embodiment, detailed description of the same configuration as in the first embodiment will be omitted.

[0091] As shown in Fig. 17, the press forming apparatus 500 of the second embodiment is configured to press-form a sector gear Ge (see Fig. 2) as a formed product from a metal plate-shaped workpiece Pm. In the following description, the formed product will be described as a sector gear Ge, but formed products other than the sector gear Ge are also possible.

[0092] Specifically, the press molding apparatus 500 includes a punch 1, a knockout 2, a die 3, and a stripper 4. Each of the punch 1, the knockout 2, the die 3, and the stripper 4 is a metal mold. The punch 1 is an example of a "first molded product extraction member" in the claims. The knockout 2 is an example of a "second molded product extraction member" in the claims. The die 3 is an example of a "second workpiece pressing member" in the claims. The stripper 4 is an example of a "first workpiece pressing member" in the claims.

[0093] Here, the vertical direction is the Z direction, the upward direction is the Z1 direction, and the downward direction is the Z2 direction. The horizontal directions that are perpendicular to each other are the X direction and the Y direction. One of the X directions is the X1 direction, and the other is the X2 direction. One of the Y directions is the Y1 direction, and the other is the Y2 direction. The Z direction is an example of a "thickness direction" in the claims. The Z1 direction is also an example of a "one side of the thickness direction" in the claims. The Z2 direction is also an example of a "other side of the thickness direction" in the claims.

[0094] (Detailed configuration of the die and stripper) Each of the die 503 and the stripper 504 of the second embodiment has a configuration for suppressing sagging Ged (see FIG. 3) of the external teeth Ge1 that occurs when punching a sector gear Ge having an irregular shape including the external teeth Ge1. The external teeth Ge1 are an example of the "irregular shape including a protrusion" in the claims.

[0095] (Detailed die configuration) Specifically, as shown in FIG. 17, the die 503 includes a die-side irregular shape forming portion 531 and a die-side recess 32.

[0096] The die side irregular shape forming portion 531 is configured to form the external teeth Ge1 (irregular shape portion of the molded product) of the sector gear Ge.

[0097] The die side deformed shape forming portion 531 has a surface on the Z1 direction side of the die side deformed shape forming portion 531. The surface on the Z1 direction side is provided with a die side swaging protruding surface 5311a, an inclined surface 5312a, and a step surface 5313a.

[0098] The die side swaging protruding surface 5311a is provided at a position protruding in the Z1 direction (toward the stripper in the thickness direction) among the surfaces on the Z1 direction side. The inclined surface 5312a is a surface of a chamfered portion provided at the tip of the die side irregular shape forming part 31. The step surface 5313a is a surface formed by a step shape provided between the inclined surface 312a and the die side swaging protruding surface 311a. The step surface 5313a is provided adjacent to the X1 direction side of the die side swaging protruding surface 311a. The step surface 5313a is a surface extending along the XY direction (horizontal direction). In this way, the step shape is formed by the die side swaging protruding surface 5311a and the step surface 5313a provided on the Z2 direction side of the die side swaging protruding surface 5311a.

[0099] (Detailed configuration of the stripper) Specifically, as shown in FIG. 17, the stripper 504 includes a stripper-side irregular shape forming portion 541 and a stripper-side recess 42.

[0100] The stripper side irregular shape forming portion 541 is configured to form the external teeth Ge1 (irregular shape portion of the molded product) of the sector gear Ge. That is, the stripper side irregular shape forming portion 541 has a shape that matches the external teeth Ge1 of the sector gear Ge when viewed from the Z1 direction side.

[0101] The stripper side deformed shape forming portion 541 has a stripper side swaging protruding surface 541a on the Z1 direction side of the stripper side deformed shape forming portion 541.

[0102] The stripper side swaging protruding surface 541a is provided at a position protruding toward the Z2 direction (toward the stripper side in the thickness direction). The stripper side swaging protruding surface 541a is a surface extending along the XY direction (horizontal direction). The stripper side swaging protruding surface 541a is provided on the Z1 direction side of the die side swaging protruding surface 311a of the die 3.

[0103] The other configurations of the second embodiment are similar to those of the first embodiment, so the description will be omitted.

[0104] (Press molding method) 18 and 19, a press-forming method using the above-mentioned press-forming apparatus 500 will be described. As described above, the sector gear Ge will be shown below as an example of a formed product.

[0105] In step S501, an upsetting process is performed. In step S501, the punch 1 and the knockout 2 arranged opposite the punch 1 on the Z2 direction side clamp the workpiece Pm by back pressure. In step S501, while the punch 1 and the knockout 2 clamp the workpiece Pm by back pressure, the stripper 504 presses the workpiece Pm from the Z1 direction side by back pressure to bite into it, and the die-side irregular shape forming portion 531 of the die 503 arranged opposite the stripper 504 on the Z2 direction side presses the workpiece Pm from the Z2 direction side to bite into it, thereby performing upsetting (see FIG. 19). In addition, as in the press molding method of the first embodiment, the step S501 of performing upsetting includes a step of upsetting the workpiece Pm in the Z direction using only the die side upsetting protrusion surface 531a, or using both the stripper side upsetting protrusion surface 541a and the die side upsetting protrusion surface 531a.

[0106] 19, in step S1 of the second embodiment, the workpiece Pm is swaged by a step shape having a step surface 5313a between the inclined surface 5312a and the die side swaging protruding surface 5311a. As a result, a material flow space 533 is formed by the step shape, and the material around the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge flows into the material flow space 33 by the amount of the die side irregular shape forming portion 531 biting in. As a result, the material can be made to flow to the portion of the workpiece Pm corresponding to the external teeth Ge1 of the sector gear Ge.

[0107] Step S2 is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0108] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0109] In the second embodiment, similarly to the first embodiment, the die-side deformed shape forming part 531 of the press forming apparatus 500 has a die-side swaging protruding surface 5311a for swaging provided at a position protruding toward the stripper 504 side in the Z direction among the surface of the stripper 504 side of the die-side deformed shape forming part 531. Thereby, by suppressing the flow of the material of the workpiece Pm toward the tip side of the external teeth Ge1 (protruding part: deformed part) of the sector gear Ge when swaging, it is possible to further suppress the occurrence of sagging of the external teeth Ge1 (protruding part: deformed part) of the sector gear Ge when punching out the sector gear Ge.

[0110] In the second embodiment, as described above, the press molding apparatus 500 includes the die side deformed shape forming part 531 having a step shape between the inclined surface 5312a provided at the tip of the die side deformed shape forming part 531 and the die side swaging protruding surface 5311a extending along the horizontal direction. As a result, the step shape can form the material flow space 33, and a gap can be formed between the workpiece Pm and the die side deformed shape forming part 531, so that the upward lifting force transmitted from the die side deformed shape forming part 531 to the stripper 4 via the workpiece Pm can be suppressed while the material flows in the material flow space 533. In addition, the above gap can suppress the stripper 4 from being lifted upward.

[0111] The other effects of the second embodiment are similar to those of the first embodiment, and therefore a description thereof will be omitted.

[0112] [Third embodiment] The configuration of the press molding method according to the third embodiment will be described with reference to Fig. 20 and Fig. 21. In the third embodiment, the press molding method includes a step S601 of performing bending. Note that in the third embodiment, detailed description of the same configuration as in the first embodiment will be omitted.

[0113] The configuration of the press forming apparatus of the third embodiment is the same as that of the press forming apparatus 100 of the first embodiment, and therefore a description thereof will be omitted.

[0114] (Press molding method) 20 and 21, a press-forming method according to the third embodiment using the press-forming apparatus 100 according to the first embodiment will be described. In the following, a sector gear Ge will be shown as an example of a formed product.

[0115] In step S601, a bending process is performed. In step S601, before the workpiece Pm is clamped by the punch 1 and knockout 2, the workpiece Pm at the boundary between the knockout 2 and the stripper 4 is bent toward the Z2 direction by the stripper 4 and knockout 2. The external teeth Ge1 are an example of an "irregular shape including a convex portion" in the claims. The knockout 2 is an example of a "second molded product removal member" in the claims. The stripper 4 is an example of a "first workpiece pressing member" in the claims.

[0116] Specifically, a force F1 is applied from the stripper 4 to the X2 direction side of the workpiece Pm by back pressure, and a force F2 is applied from the knockout 2 to the X1 direction side of the workpiece Pm by back pressure, thereby bending the portion Pbe between the knockout 2 and the stripper 4 in the X direction toward the Z2 direction.

[0117] It should be noted that steps S602 and S603 are the same as steps S1 and S2 in the press molding method of the first embodiment, and therefore a description thereof will be omitted.

[0118] (Effects of the third embodiment) In the third embodiment, the following effects can be obtained.

[0119] In the third embodiment, similarly to the first embodiment, the die-side deformed shape forming part 31 of the press forming apparatus 100 has a die-side swaging protruding surface 311a for swaging provided at a position protruding toward the stripper 4 side in the Z direction among the surface 31a on the stripper 4 side of the die-side deformed shape forming part 31. This suppresses the flow of material of the workpiece Pm toward the tip side of the external teeth Ge1 (protruding portion: deformed portion) of the sector gear Ge when swaging, thereby further suppressing the occurrence of sagging of the external teeth Ge1 (protruding portion: deformed portion) of the sector gear Ge when punching out the sector gear Ge.

[0120] The other effects of the third embodiment are similar to those of the first embodiment, and therefore a description thereof will be omitted.

[0121] [Variations] The above-described embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the description of the above-described embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0122] For example, in the above first to third embodiments, the press molding method is described as an example of molding a sector gear Ge as a molded product, but the present invention is not limited thereto. In the present invention, the press molding method may be an element Er that constitutes a transmission belt that is attached between a pair of pulleys of a continuously variable transmission by being annularly arranged by an endless ring, as in a first modified example shown in FIG. 22. Here, when press molding the element Er, as shown in FIG. 23, in the die 703, for example, a die side irregular shape forming portion 731 having a die side swaging protruding surface 7311a is provided around the corner portion Cr1 and the corner portion Cr2 at both ends of the slot of the element Er. Also, as in a second modified example shown in FIG. 24, a die side irregular shape forming portion 831 having a die side swaging protruding surface 8311a may be provided around the corner portion Cr3 of the molded product.

[0123] In the above first to third embodiments, the press molding method includes a step of punching out a molded product from the workpiece Pm by moving the die 3 in the Z1 direction while the punch 1 and knockout 2 sandwich the workpiece Pm by back pressure and the stripper 4 presses the workpiece Pm from the Z1 direction side by back pressure, but the present invention is not limited to this. In the present invention, the press molding method may include a step of punching out a molded product from the workpiece Pm by moving the stripper while the punch and knockout sandwich the workpiece by back pressure and the die presses the workpiece.

[0124] In the above first to third embodiments, the press molding method includes a step of sandwiching the workpiece Pm between the punch 1 and knockout 2 by back pressure, and then upsetting the workpiece Pm by the die 3 in a state in which the stripper 4 presses the workpiece Pm from the Z1 direction side by back pressure, but the present invention is not limited to this. In the present invention, the press molding method may include sandwiching the workpiece between the punch and knockout after upsetting by the die in a state in which the stripper presses the workpiece by back pressure.

[0125] In the above-described first embodiment, the surface 41a of the stripper side deformed forming portion 41 has the stripper side swaging protruding surface 411a and the inclined surface 412a, but the present invention is not limited to this. In the present invention, when the thickness of the workpiece is large as in the third modified example shown in Fig. 25, the stripper side deformed forming portion 941 may have only the stripper side swaging protruding surface 9411a.

[0126] In the above first to third embodiments, the punch 1 is fixed so as not to move in either the Z1 direction or the Z2 direction, but the present invention is not limited to this. In the present invention, the punch may be configured to move by hydraulic pressure supplied from a hydraulic device. [Explanation of symbols]

[0127] 1 Punch (first molded product extraction member, second molded product extraction member) 2 Knockout (first molded product removal part, second molded product removal part) 3, 503, 703 Die (first workpiece pressing member, second workpiece pressing member) 4, 504 Stripper (first workpiece pressing member, second workpiece pressing member) 31, 531, 731, 831 Die side irregular shape forming part (one side irregular shape forming part) 32 Die side recess (one side recess) 100, 500 Press molding equipment 311a, 5311a, 7311a, 8311a Die side projection surface for upsetting (one side projection surface for upsetting) 312a, 5312a Slope (first slope) 313a Slope (second slope) Cr1, Cr2, Cr3 corner Er element (molded product) Ge Sector gear (molded product) Ge1 External teeth (convex part) Pm Work material θ1, θ2 Tilt angle

Claims

1. a first molded product extraction member and a second molded product extraction member opposed to one side of the first molded product extraction member in the thickness direction, the first molded product extraction member sandwiching a metal plate-shaped workpiece for press-molding a molded product having an irregular shape including a convex portion or a corner portion in the thickness direction of the workpiece; a first workpiece pressing member provided on a side of the first molded product removal member and pressing from the other side in the thickness direction; a second workpiece pressing member including a one-side irregular shape forming portion for forming an irregular shape of the molded product, the second workpiece pressing member being disposed opposite to one side of the first workpiece pressing member in the thickness direction, and punching out the molded product from the workpiece while pressing from one side in the thickness direction by the first workpiece pressing member; the one-side deformed shape forming part has a one-side swaging protruding surface for performing swaging, the one-side swaging protruding surface being provided at a position protruding toward the first workpiece pressing member in the thickness direction on a surface of the one-side deformed shape forming part facing the first workpiece pressing member.

2. 2. The press molding apparatus according to claim 1, wherein the one-side irregular shape forming portion has a two-step tapered shape or a step shape having a first inclined surface provided at a tip and the one-side swaging protruding surface extending along the horizontal direction, and a second inclined surface having an inclination angle with respect to a direction perpendicular to the thickness direction smaller than an inclination angle of the first inclined surface between the first inclined surface and the one-side swaging protruding surface extending along the horizontal direction.

3. 2. The press forming apparatus according to claim 1, wherein the second workpiece pressing member further has a one-side recess recessed in the thickness direction on a side opposite to the first workpiece pressing member so that the workpiece does not come into contact with a portion of the second workpiece pressing member that is outer than the one-side swaging protruding surface when the workpiece is swaged.

4. A press molding method for punching out a molded product having a irregular shape including a convex portion or a corner portion while applying a back pressure to a metal plate-shaped workpiece in a thickness direction of the workpiece, a step of clamping the workpiece between a first molded product removal member for punching out and removing the molded product and a second molded product removal member arranged opposite to one side of the first molded product removal member in the thickness direction and for removing the molded product; a first workpiece pressing member disposed to the side of the first molded product removal member pressing the workpiece from the other side in the thickness direction by back pressure, and a one-side irregular shape forming portion of a second workpiece pressing member disposed opposite to one side in the thickness direction of the first workpiece pressing member, which forms the irregular shape of the molded product, pressing the workpiece from the one side in the thickness direction to bite into it, thereby upsetting the workpiece; and after the step of upsetting the workpiece, a step of punching out the shaped product from the workpiece by the second workpiece pressing member including the one-side irregular shape forming portion, a press molding method, the step of performing the upsetting includes a step of performing upsetting on the workpiece by a one-side upsetting protruding surface provided at a position protruding toward the first workpiece pressing member in the thickness direction on a surface of the one-side deformed forming portion facing the first workpiece pressing member in the thickness direction.

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