Stamping die and stamping method

Abstract

The stamping die (13) of the present invention forms a stamped part (1). The stamped part has: a top plate portion (3) having a concavo-convex edge portion (11) in which a convex edge portion (11a) protruding outward in the in-plane direction and a concave edge portion (11b) recessed inward in the in-plane direction are continuous via a connecting edge portion (11c); and a flange portion (5) continuously formed on the concavo-convex edge portion (11) in the top plate portion (3). The stamping die includes: an upper die (15) and a lower die (17); and a lower backing plate (21) and an upper backing plate (23) that cooperate with the upper die (15) and the lower die (17) to clamp a blank (19). In the initial stage of forming, a flange portion (5) is formed on the convex edge portion (11a), and a twisted shape portion (25) having a shape that is continuous with the flange portion (5) and twisted toward the concave edge portion (11b) is formed. In the later stage of forming, the twisted shape portion (25) is formed into a flange portion (5), and a flange portion (5) is formed on the concave edge portion (11b), and the target shape can be formed.

Description

Technical Field

[0001] The present invention relates to press forming dies and a press forming method for press forming accessories such as automotive parts from a metal sheet, and particularly to a press forming die and a press forming method for a press formed part having a top portion with convex and concave parts in the in-plane direction and a flange portion formed continuously with the top portion. Background Art

[0002] In recent years, due to the weight reduction of automotive bodies caused by environmental problems, high-strength steel sheets are widely used for automotive parts. However, compared with steel sheets having low strength, high-strength steel sheets lack ductility and are prone to fracture during processing. In addition, when high-strength steel sheets are used, thinning is also carried out for further weight reduction, so there is also a problem that buckling of the steel sheet is likely to occur and wrinkles are likely to occur during press forming. Therefore, there is a strong demand for the development of a press forming method for suppressing fracture and wrinkles.

[0003] For example, Patent Document 1 discloses a press forming method for manufacturing an automotive part that is prone to wrinkles and stretch flange fractures inside the product without forming defects by using a wrinkle suppression blank holder that is separately driven from a punch and a die for press. According to the method disclosed in Patent Document 1, an automotive part that is prone to wrinkles and fractures inside the product can be manufactured without forming defects.

[0004] Patent Document 1: Japanese Patent No. 6032374 Gazette

[0005] However, the press forming method disclosed in Patent Document 1 is a method that requires the use of a wrinkle suppression blank holder to hold down the inside of the product away from the flange. Therefore, there is a problem that it cannot be applied to a shape in which wrinkles and fractures occur in the flange portion itself. Summary of the Invention

[0006] The present invention has been completed in view of the above problems, and an object thereof is to provide a stamping die and a stamping method that can also be applied to a stamped part in which wrinkles and cracks are generated in the flange itself and can simultaneously suppress wrinkles and cracks generated in the flange.

[0007] The stamping die according to the present invention forms a stamped part, and the stamped part has: a top plate portion having a convex and concave outer edge portion in which a convex outer edge part and a concave outer edge part are continuous via a connecting outer edge part, the convex outer edge part protruding outward in the in-plane direction, and the concave outer edge part being recessed inward in the in-plane direction; and a flange portion formed continuously in the convex and concave outer edge portion of the top plate portion. The stamping die includes: an upper stage pressing die and a lower stage pressing die that bend-form the flange portion along the convex and concave outer edge portion; and a lower blank holder and an upper blank holder that cooperate with the upper die and the lower die to clamp a blank. The upper die has: a convex edge flange forming portion that forms a flange portion in the convex edge portion; a concave edge flange forming portion that forms a flange portion in the concave edge portion; and a connecting edge flange forming portion that forms a flange portion in the connecting edge portion. The convex edge flange forming portion protrudes more in the press-forming direction than the concave edge flange forming portion, and the connecting edge flange forming portion is inclined from the convex edge flange forming portion toward the concave edge flange forming portion. The lower blank holder has a shape corresponding to the convex edge flange forming portion, the concave edge flange forming portion, and the connecting edge flange forming portion formed in the upper die. In the initial stage of forming, the convex edge flange forming portion forms a flange portion in the convex edge portion, and the connecting edge flange forming portion forms a torsional deformation part having a shape that is continuous with the flange portion and is twisted toward the concave edge portion. In the later stage of forming, the connecting edge flange forming portion forms the torsional deformation part into a flange portion, and the concave edge flange forming portion forms a flange portion in the concave edge portion, so that a target shape can be formed.

[0008] The stamping forming method according to the present invention uses the stamping forming die according to the present invention to form a stamping formed part, and the stamping formed part has: a top plate portion having a concavo-convex edge portion in which a convex edge portion and a concave edge portion are continuous via a connecting edge portion, the convex edge portion protruding outward in the in-plane direction, and the concave edge portion being recessed inward in the in-plane direction; and a flange portion formed continuously with the concavo-convex edge portion in the top plate portion. The stamping forming method includes: an initial forming process in which a part of a blank is clamped by the upper backing plate and the lower die, and a part of the blank is supported by the lower backing plate, and the upper die is moved in the stamping forming direction, whereby a flange portion is formed on the convex edge portion by the convex edge flange forming portion, and a twisted shape portion having a shape twisted toward the concave edge portion is formed continuously with the flange portion by the connecting edge flange forming portion; and a final forming process in which the upper die and the lower backing plate are moved in the stamping forming direction, the twisted shape portion is formed into a flange portion by the connecting edge flange forming portion, and a flange portion is formed on the concave edge portion by the concave edge flange forming portion to form a target shape.

[0009] According to the stamping forming die of the present invention, it can be applied to a stamping formed part in which wrinkles and cracks are generated in the flange itself, and can suppress wrinkles and cracks generated in the flange at the same time. Moreover, the die can perform stamping forming through the movement in the same direction, that is, one action, and can perform stamping forming efficiently. Description of the Drawings

[0010] Figure 1 It is an explanatory view (part 1) of the stamping forming die according to an embodiment of the present invention.

[0011] Figure 2 It is an explanatory view (part 2) of the stamping forming die according to an embodiment of the present invention.

[0012] Figure 3 It is an explanatory view (part 3) of the stamping forming die according to an embodiment of the present invention.

[0013] Figure 4 It is an explanatory view (part 4) of the stamping forming die according to an embodiment of the present invention.

[0014] Figure 5 It is an explanatory view of the stamping forming method according to an embodiment of the present invention.

[0015] Figure 6 It is an explanatory view (part 1) of the state of the die in the pre-forming process before the start of forming of the stamping forming method according to an embodiment of the present invention.

[0016] Figure 7It is an explanatory diagram (the second one) of the state of the die in the pre-forming process of the stamping forming method according to the embodiment of the present invention.

[0017] Figure 8 It is an explanatory diagram of the state of the die in the initial forming process of the stamping forming method according to the embodiment of the present invention.

[0018] Figure 9 It is from Figure 5 An enlarged view observed from the direction of the thick arrow of the AA part in the formed part of the initial forming process.

[0019] Figure 10 It is an explanatory diagram for explaining the mechanism of suppressing the generation of wrinkles in the initial forming process.

[0020] Figure 11 It is an explanatory diagram of the state of the die in the later forming process of the stamping forming method according to the embodiment of the present invention.

[0021] Figure 12 It is from Figure 5 An enlarged view observed from the direction of the thick arrow of the BB part in the target shape of the later forming process.

[0022] Figure 13 It is an explanatory diagram for explaining the mechanism of suppressing the generation of cracks in the later forming process.

[0023] Figure 14 It is an explanatory diagram for explaining the target shape in the embodiment and the problems generated in the forming process of the target shape.

[0024] Figure 15 It is for Figure 14 An explanatory diagram for explaining the mechanism of generating wrinkles and cracks in the forming process of the shown target shape. Detailed Embodiment

[0025] Before explaining the stamping die and the stamping forming method according to the present embodiment, regarding an example of the stamping formed part that is the forming object of the present invention, based on Figure 14 , Figure 15 its shape and problems will be explained. Figure 14The drawn formed part 1 shown is a perspective view of a slide door rail as an automotive part, having a top plate portion 3 and a flange portion 5. The top plate portion 3 has a convex part 7 that protrudes outward in the in-plane direction and a concave part 9 that is adjacent to the convex part 7 and recesses inward in the in-plane direction. The outer periphery of the top plate portion 3 becomes an uneven edge portion 11 composed of the outer periphery of the convex part 7, that is, a convex edge portion 11a, the outer periphery of the concave part 9, that is, a concave edge portion 11b, and a connecting edge portion 11c that connects the convex edge portion 11a and the concave edge portion 11b. And, the flange portion 5 is formed on the uneven edge portion 11. Further, in the case of an actual slide door rail, a bent portion is formed on the edge portion of the top plate portion 3 that faces the uneven edge portion 11 where the flange portion 5 is formed, but in Figure 14 the drawing of this bent portion is omitted.

[0026] In the case where such a drawn formed part 1 is formed by an existing drawing forming method, in the flange portion 5 formed on the convex edge portion 11a, it becomes a shrink flange forming (part a enclosed by a circular dotted line in the figure), and wrinkles are likely to occur due to excess metal. On the other hand, in the flange portion 5 formed on the concave edge portion 11b, it becomes a stretch flange forming (part b enclosed by a circular dotted line in the figure), and cracks are likely to occur due to metal shortage.

[0027] Based on Figure 15 the mechanism of generation of these wrinkles and cracks will be described. Figure 15 is a view for explaining the metal flow during the forming process in the EE portion enclosed by a dotted line in Figure 14 , showing a top view ([[]]END]] Figure 15 of (a)) and a side view ([[]]END]] Figure 15 of (b)) Figure 14 of the state. Additionally, in Figure 15In the figure, the dashed line is the front end of the blank before forming, and the solid line is the edge of the flange portion 5 formed into the target shape. In addition, points D and B in the figure are the points corresponding to the R end points (the boundary between a curve and a straight line) of the convex edge portion 11a in the blank before forming. Correspondingly, in the top view, the intersection points of the lines perpendicular to the edge of the target shape from points D and B with the edge of the target shape are points D' and B'. Similarly, points A and E in the figure are the points corresponding to the R end points of the concave edge portion 11b in the blank before forming. Correspondingly, in the top view, the intersection points of the lines perpendicular to the edge of the target shape from points E and A with the edge of the target shape are points A' and E'. As Figure 15 shown in the top view of (a), the material flows substantially perpendicular to the ridge line (curved line). Therefore, in portion a, it flows in the direction approaching the material, and in portion b, it flows in the direction away from the material. Therefore, wrinkles are likely to occur in portion a, and cracks are likely to occur in portion b.

[0028] To solve such problems, the inventors considered that by interposing a preformed part that easily allows the material to flow from the portion where the shrinkage flange deformation occurs to the portion where the stretching flange deformation occurs during forming, the concentration of compressive strain and tensile strain in each portion can be avoided, and a stamping die capable of realizing such a stamping method was conceived. Specifically, the stamping die has the following structure.

[0029] The stamping die 13 according to the present embodiment is a die for forming a stamped part 1, and the formed stamped part 1 is, for example, as Figure 14 shown, having: a top plate portion 3 having an uneven edge portion 11 in which a convex edge portion 11a and a concave edge portion 11b are continuous via a connecting edge portion 11c, the convex edge portion 11a protruding outward in the in-plane direction, and the concave edge portion 11b recessed inward in the in-plane direction; and a flange portion 5 formed on the uneven edge portion 11 in the top plate portion 3 and continuous with the uneven edge portion 11 in the top plate portion 3. In addition, as Figures 1 to 4 shown, the stamping die 13 according to the present embodiment includes: an upper die 15 and a lower die 17 that bend and form the flange portion 5 along the uneven edge portion 11 ( Figure 5 ); and a lower backing plate 21 and an upper backing plate 23 that cooperate with the upper die 15 and the lower die 17 to clamp the blank 19. In addition, the upper and lower of the upper die and the lower die represent a relative relationship, not necessarily in the upper or lower position, but only represent a paired relationship. The stamping die 13 of the present embodiment clamps the blank 19 ( Figure 6)It is placed on the lower die 17 and clamped by the upper backing plate 23, and the upper die 15 and the lower backing plate 21 are moved, whereby the flange portion 5 is bent and formed at the outer edge of the blank 19. Concave and convex surfaces are formed at the bending edge portions of the upper die 15 and the lower die 17, and the concave and convex surfaces are concave and convex in the in-plane direction of the placed blank 19 in the same manner as the concave and convex edge portions 11 of the top plate portion 3.

[0030] The upper die 15 has: a convex-edge flange forming portion 15a for forming the flange portion 5 at the convex edge portion 11a; a concave-edge flange forming portion 15b for forming the flange portion 5 at the concave edge portion 11b; and a connecting-edge flange forming portion 15c for forming the flange portion 5 at the connecting edge portion 11c (see Figure 4 ). Moreover, the convex-edge flange forming portion 15a protrudes more in the stamping direction (the out-of-plane direction of the placed blank 19, which is downward in Figures 1 to 4 ) than the concave-edge flange forming portion 15b, and the connecting-edge flange forming portion 15c is inclined from the convex-edge flange forming portion 15a toward the concave-edge flange forming portion 15b (see Figure 2 、 Figure 4 ).

[0031] In addition, the lower backing plate 21 has shapes respectively corresponding to the convex-edge flange forming portion 15a, the concave-edge flange forming portion 15b, and the connecting-edge flange forming portion 15c formed on the upper die 15. That is, the portion of the lower backing plate 21 corresponding to the convex-edge flange forming portion 15a of the upper die 15 (the convex-edge flange forming portion 21a of the lower backing plate) is recessed in the stamping direction compared to the portion of the lower backing plate 21 corresponding to the concave-edge flange forming portion 15b of the upper die 15 (the concave-edge flange forming portion 21b of the lower backing plate). In addition, the portion corresponding to the connecting-edge flange forming portion 15c of the upper die 15 (the connecting-edge flange forming portion 21c of the lower backing plate) is inclined from the concave-edge flange forming portion 21b of the lower backing plate toward the convex-edge flange forming portion 21a of the lower backing plate (see Figure 1 、 Figure 3 ).

[0032] Next, a method for forming the sliding door rail member shown in Figure 14 is described using the stamping die 13 of the present embodiment as described above. As shown in Figure 5 , the stamping method of the present embodiment includes a pre-forming start process S1, an initial forming process S3, and a final forming process S5 of setting the blank 19 in the stamping die 13. Hereinafter, each process will be described in detail based on Figures 5 to 13 . In addition, in the description of the movement of the die in Figure 7 、 Figure 8 、 Figure 11 , the upper die 15 and the upper backing plate 23 are perspective views in order to show the forming state of the blank 19.

[0033] <Before the forming start process>

[0034] In the before the forming start process S1, as Figure 6 shown, a blank 19 made of a metal sheet is placed on the lower die 17, and as Figure 7 shown, a part of the blank 19 is clamped by the upper backing plate 23. At this time, the uppermost surface of the lower backing plate 21 (for example, the lower backing plate concave edge flange forming portion 21b) is coplanar with the upper surface of the lower die 17. Moreover, the portion of the blank 19 corresponding to the top plate portion 3 is disposed on the lower die 17, and the portion of the blank 19 corresponding to the flange portion 5 is disposed on the lower backing plate concave edge flange forming portion 21b in the lower backing plate 21.

[0035] <Initial forming process>

[0036] In the initial forming process S3, as Figure 8 shown, while a part of the blank 19 is clamped by the upper backing plate 23 and the lower die 17, a part of the blank 19 is supported by the lower backing plate 21, and the upper die 15 is relatively moved in the stamping forming direction. As a result, a flange portion 5 is formed on the convex edge portion 11a by the convex edge flange forming portion 15a, and a twisted shape portion 25 having a shape twisted toward the concave edge portion 11b is continuously formed with the flange portion 5 by the connecting edge flange forming portion 15c.

[0037] In the initial forming process S3, a flange portion 5 is formed on the convex edge portion 11a of the top plate portion 3, but the concave edge portion 11b is supported by the lower backing plate concave edge flange forming portion 21b, so a flange portion 5 is not formed on the concave edge portion 11b of the top plate portion 3. Therefore, a twisted shape portion 25 is formed on the connecting edge portion 11c from the convex edge portion 11a to the concave edge portion 11b instead of a flange portion 5. As Figure 9 shown, one end side of the twisted shape portion 25 is connected to the flange portion 5 formed on the convex edge portion 11a, and the other end side is connected to the flat top plate portion 3, so it becomes a twisted shape. When the twisted shape portion 25 is formed, as Figure 9 the arrow shows, metal inflow occurs from the formed flange portion 5 side toward the flat direction, and the remaining material in the flange deformation is relaxed, and the generation of wrinkles can be suppressed.

[0038] Based on Figure 10 to explain the mechanism of the material flow generated. Figure 10 Is a diagram for explaining the material flow during the forming process of the CC portion enclosed by a dotted line in Figure 9 , showing a top view and a side view Figure 9 of the state. In addition, in Figure 10In the figure, the thin dashed line is the outer edge of the blank before forming, the thick dashed line is the outer edge of the twisted shape portion 25, and the solid line is the outer edge of the target shape. Points A to E and points A' to E' in the figure are the same points as Figure 15 the points shown. That is, point A in the figure is the R end point of the curved portion in the blank 19 and becomes the front end position of the twisted shape portion 25 with almost no deformation. Point B is the point corresponding to the R end point of one of the existing blank portions where shrink flange deformation occurs, and point B' is the intersection point of the line perpendicular to the outer edge of the twisted shape portion 25 from point B in the top view and the outer edge of the twisted shape portion 25. Point D is the R end point of the curved portion in the blank 19, and point D' is the intersection point of the line perpendicular to the outer edge of the target shape from point D in the top view and the outer edge of the target shape.

[0039] Due to the shrink flange deformation, the distance from point B' to point D' is shorter than the distance from point B to point D (B'D' < BD), and wrinkles are likely to occur in the flange portion 5 formed on the convex edge portion 11a due to the remaining material. On the other hand, when observed three-dimensionally, the distance from point A to point B' is longer than the distance from point A to point B (AB' > AB), so the material is stretched toward point A and flows deviating from "substantially perpendicular to the ridge line". Therefore, compared with the material flow of the arrow in the existing Figure 15 wrinkle generation area, the material flow shown by the arrow closer to point A is generated. Through this material flow, the remaining material in the shrink flange deformation formed in the initial forming process is alleviated, and the generation of wrinkles can be suppressed. Figure 10

[0040] <Post-forming process>

[0041] In the post-forming process S5, as Figure 11 shown, the upper die 15 and the lower backing plate 21 are moved in the stamping direction. Thereby, the twisted shape portion 25 is formed into the flange portion 5 by the connecting edge flange forming portion 15c, and the flange portion 5 is formed on the concave edge portion 11b by the concave edge flange forming portion 15b, and the target shape is formed. During the forming process of the post-forming process S5, as Figure 12 the thick arrow shown, material flows into the stretching flange deformation portion from the twisted shape portion 25. Therefore, the material shortage in the stretching flange deformation portion is alleviated, and the generation of cracks can be suppressed.

[0042] Based on Figure 13 the mechanism of the material flow generated will be described. Figure 13 is a diagram for explaining the material flow during the forming process of the DD portion enclosed by the dashed line in Figure 12 and shows the states of top view observation and side view observation Figure 12 In addition, in Figure 13In [the figure], the thin dashed line is the edge of the blank before forming, the thick dashed line is the edge of the twisted shape portion 25, and the solid line is the edge of the flange portion 5 in the target shape.

[0043] In addition, points A to E and points A' to E' in the figure are the same points as Figure 15 , Figure 10 the points shown. That is, point A' in the figure is the intersection point of the line perpendicular to the edge line of the target shape from point A in the top view and the target shape. Point E is the point corresponding to the R end of one of the existing blank portions where the stretched flange deformation occurs, and point E' is the intersection point of the line perpendicular to the edge of the target shape from point E in the top view and the edge of the target shape. Due to the stretched flange deformation, the distance from point A' to point E' is longer than the distance from point A to point E (A'E' > AE), and cracks are likely to occur in the flange portion 5 formed in the concave edge portion 11b due to insufficient material. On the other hand, when observed three-dimensionally, the distance from point D' to point E' is shorter than the distance from point D' to point E (D'E' < D'E'), so the material is pressed toward the A' side and flows deviating from "substantially perpendicular to the edge line". Therefore, compared with the material flow of the arrow in the crack generation region of the existing Figure 15 , a material flow indicated by an arrow closer to point A' Figure 13 is generated. Through this material flow, the material shortage in the stretched flange deformation formed in the later forming process S5 is alleviated, and the generation of cracks can be suppressed.

[0044] As described above, if the stamping die 13 of the present embodiment is used, in the initial stage of forming, the flange portion 5 is formed in the convex edge portion 11a by the convex edge flange forming portion 15a, and the twisted shape portion 25 having a shape continuous with the flange portion 5 and twisted toward the concave edge portion 11b is formed by the connecting edge flange forming portion 15c. In the later stage of forming, the twisted shape portion 25 is formed into the flange portion 5 by the connecting edge flange forming portion 15c, and the flange portion 5 is formed in the concave edge portion 11b by the concave edge flange forming portion 15b, and the target shape can be formed. Therefore, in the initial stage of forming, by first forming only the portion that becomes the shrink flange deformation, the twisted shape portion 25 that promotes the flow of the material toward the portion that becomes the stretched flange deformation is formed. In the later stage of forming, by forming the portion that becomes the stretched flange deformation, the target shape can be formed by suppressing the material shortage due to the stretched flange deformation through the material flow from the twisted shape portion 25.

[0045] In this way, by dispersing the strain at the dangerous parts where stretching flange cracks are generated and the dangerous parts where shrinkage flange wrinkles are generated, in the initial forming process S3, the generation of wrinkles caused by shrinkage flange deformation is suppressed, and in the later forming process S5, the generation of cracks caused by stretching flange deformation is suppressed, and the generation of wrinkles and cracks can be suppressed throughout the process. Moreover, the die can perform stamping forming through the movement in the same direction, that is, one action, and stamping forming can be efficiently performed.

[0046] Example

[0047] To confirm the effects of the present invention, stamping forming was carried out using the example of the sliding door rail member Figure 14 shown as the target shape. The material was a steel plate with a tensile strength of 1180 MPa grade and a plate thickness of 1.4 mm. First, as a comparative example, the target shape was formed through one process without forming the torsional shape portion 25, and stamping forming based on pad forming using a pressure pad to press the top plate portion was carried out. Next, as an example of the present invention, the stamping forming die 13 described in the embodiment was used to perform an initial forming process S3 including forming a flange portion 5 at the convex edge portion 11a and forming a torsional shape portion 25 at the connecting edge portion 11c, and a later forming process S5 of forming the torsional shape portion 25 into a flange portion 5 and forming a flange portion 5 at the concave edge portion 11b, and any forming process was pad forming using a pressure pad to press the top plate portion.

[0048] In the case of the comparative example, wrinkles were generated at the a portion Figure 14 shown, and cracks were generated at the b portion, and the target shape could not be obtained. On the other hand, in the example of the present invention, neither cracks nor wrinkles were generated in the flange portion 5, and a high-quality stamping formed part could be obtained. From the above, it is shown that the present invention is effective for suppressing stretching flange cracks and shrinkage flange wrinkles during the forming of a stamping formed part in which the top plate portion 3 has unevenness in the in-plane direction.

[0049] Industrial applicability

[0050] According to the present invention, it is possible to provide a stamping forming die and a stamping forming method that can also be applied to a stamping formed part in which wrinkles and cracks are generated in the flange itself and can simultaneously suppress the wrinkles and cracks generated in the flange.

[0051] Explanation of reference numerals

[0052] 1... Stamped forming part; 3... Top plate part; 5... Flange part; 7... Protrusion part; 9... Recess part; 11... Concave-convex edge part; 11a... Convex edge part; 11b... Concave edge part; 11c... Connecting edge part; 13... Stamped forming die; 15... Upper die; 15a... Convex edge flange forming part; 15b... Concave edge flange forming part; 15c... Connecting edge flange forming part; 17... Lower die; 19... Blank; 21... Lower backing plate; 21a... Lower backing plate convex edge flange forming part; 21b... Lower backing plate concave edge flange forming part; 21c... Lower backing plate connecting edge flange forming part; 23... Upper backing plate; 25... Twisted shape part.

Claims

1. A stamping die for forming a stamped part, the stamped part having: a top plate portion having a concavo-convex edge portion in which a convex edge portion and a concave edge portion are continuous via a connecting edge portion, the convex edge portion protruding outward in the in-plane direction, and the concave edge portion recessing inward in the in-plane direction; and a flange portion formed continuously with the concavo-convex edge portion in the top plate portion, The stamping die is characterized by comprising: an upper die and a lower die for bending and forming the flange portion along the concavo-convex edge portion; and a lower backing plate and an upper backing plate for clamping a blank in cooperation with the upper die and the lower die, The upper die has: a convex-edge flange forming portion for forming a flange portion at the convex edge portion; a concave-edge flange forming portion for forming a flange portion at the concave edge portion; and a connecting-edge flange forming portion for forming a flange portion at the connecting edge portion, the convex-edge flange forming portion protruding more in the stamping direction than the concave-edge flange forming portion, and the connecting-edge flange forming portion being inclined from the convex-edge flange forming portion toward the concave-edge flange forming portion, The lower backing plate has shapes respectively corresponding to the convex-edge flange forming portion, the concave-edge flange forming portion, and the connecting-edge flange forming portion formed in the upper die, In the initial stage of forming, a flange portion is formed at the convex edge portion by the convex-edge flange forming portion, and a twisted shape portion having a shape continuous with the flange portion and twisted toward the concave edge portion is formed by the connecting-edge flange forming portion, In the later stage of forming, the twisted shape portion is formed into a flange portion by the connecting-edge flange forming portion, and a flange portion is formed at the concave edge portion by the concave-edge flange forming portion, enabling the formation of a target shape.

2. A stamping method using the stamping die according to claim 1 to form a stamped part, the stamped part having: a top plate portion having a concavo-convex edge portion in which a convex edge portion and a concave edge portion are continuous via a connecting edge portion, the convex edge portion protruding outward in the in-plane direction, and the concave edge portion recessing inward in the in-plane direction; and a flange portion formed continuously with the concavo-convex edge portion in the top plate portion, The stamping method is characterized by including: an initial forming step in which a part of the blank is clamped by the upper backing plate and the lower die, and a part of the blank is supported by the lower backing plate, and the upper die is moved in the stamping direction, whereby a flange portion is formed at the convex edge portion by the convex-edge flange forming portion, and a twisted shape portion having a shape continuous with the flange portion and twisted toward the concave edge portion is formed by the connecting-edge flange forming portion; and a later forming step in which the upper die and the lower backing plate are moved in the stamping direction, the twisted shape portion is formed into a flange portion by the connecting-edge flange forming portion, and a flange portion is formed at the concave edge portion by the concave-edge flange forming portion to form a target shape.

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