Method for manufacturing press-molded article, and press-molding device

Abstract

A method for manufacturing a press-molded article (300, 400) is provided with a step for sandwiching a blank (200) between a die (20, 20B) and a swaging member (30, 30A-30F), and a step for pressing the blank (200) in a pressing direction (Z) by a punch (10, 10B). When viewed from the punching direction (Z), an edge (24) of the die (20, 20B) on the punch (10, 10B) side includes a curved portion (241) that is curved so as to protrude toward the punch (10, 10B) side and extends so as to have a radius of curvature of less than 400 mm. When viewed from the pressing direction (Z), the distance (C) between the edge (34) of the swaging member (30, 30A-30F) on the punch (10, 10B) side and the edge (24) of the die (20, 20B) on the punch (10, 10B) side on the perpendicular line in the direction of extension of the edge (24) of the die (20, 20B) varies along the edge (24) of the die (20, 20B), said distance (C) being between the edge (34) of the swaging member (30, 30A-30F) on the punch (10, 10B) side and the edge (24) of the die (20, 20B) on the punch (10, 10B) side. The interval (C) is the smallest at the bent portion (241) when viewed from the press direction (Z).

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a stamped product and a stamping device. Background Art

[0002] Press-formed products are used as structural members for automobiles, for example. Press-formed products are manufactured by press-forming a blank using a punch and a die. The blank is pressed into a desired shape by the punch toward the die.

[0003] Patent document 1 discloses a method for manufacturing a press-formed product using a blanking plate in addition to a punch and a die. In patent document 1, the side surface of the punch and the side surface of the die cooperating with the punch include a curved surface. In patent document 1, the die is moved relative to the punch along the side surface of the punch while a blank having a stepped shape is clamped by the punch and the blanking plate. Thus, a press-formed product is formed from the blank.

[0004] Patent document 2 also discloses a method for manufacturing a stamped product using a punch, a die, and a pressure plate. In patent document 2, the edge of the upper surface of the punch has a centrally concave shape when viewed from above. The die has a shape corresponding to the punch. In patent document 2, a blank placed on the upper surface of the punch is pressed by a pressure plate to form a draw rib (bead) on the blank. Afterwards, the blank is bent by the punch and the die to form a stamped product.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6052478

[0008] Patent Document 2: Japanese Patent No. 6202059 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In Patent Documents 1 and 2, the edge of the die on the punch side includes a curved portion. The curved portion is a portion that curves convexly toward the punch side when the die is viewed from above. In this case, when the blank is pressed into the punch during stamping, when the blank is pulled toward the edge of the die on the punch side, the portion of the blank pulled toward the curved portion is stretched in the extending direction of the curved portion. If the blank is stretched and the sheet thickness of the blank is reduced, there is a possibility that cracks will occur in the blank.

[0011] The present disclosure aims to suppress the occurrence of cracks in a blank during the process of manufacturing a press-formed product.

[0012] Solutions for solving problems

[0013] The manufacturing method of the stamped product disclosed in the present invention comprises the steps of clamping the blank by a die and a pressing member and pressing the blank in the stamping direction by a punch. When observed from the stamping direction, the edge of the die on the punch side includes a curved portion that is convexly curved toward the punch side and extends with a radius of curvature less than 400 mm. When observed from the stamping direction, the interval between the edge of the pressing member on the punch side and the edge of the die on the punch side on the vertical line of the extension direction of the edge of the die changes along the edge of the die. When observed from the stamping direction, the interval is smallest at the curved portion.

[0014] Effects of the Invention

[0015] According to the present disclosure, it is possible to suppress the occurrence of cracks in the blank during the process of manufacturing a press-formed product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic perspective view of the press forming device according to the first embodiment.

[0017] Figure 2 yes Figure 1 A cross-sectional view of the stamping device shown.

[0018] Figure 3 It is schematically indicated Figure 1 A diagram showing the relationship between a punch, a die, and a pressing member included in the stamping forming device when viewed from the stamping direction.

[0019] Figure 4A It is a schematic diagram for explaining the method for manufacturing a press-formed product according to the first embodiment.

[0020] Figure 4B This is a schematic diagram for explaining the method for producing a press-formed product according to the first embodiment.

[0021] Figure 4C It is a schematic diagram for explaining the method for manufacturing a press-formed product according to the first embodiment.

[0022] Figure 4D It is a schematic diagram for explaining the method for manufacturing a press-formed product according to the first embodiment.

[0023] Figure 4E It is a schematic diagram for explaining the method for manufacturing a press-formed product according to the first embodiment.

[0024] Figure 4F It is a schematic diagram for explaining the method for manufacturing a press-formed product according to the first embodiment.

[0025] Figure 5This is a diagram schematically showing the relationship between a punch, a die, and a pressing member included in the press forming apparatus of the second embodiment when viewed from the press direction.

[0026] Figure 6 This is a schematic perspective view of a press-formed product manufactured by the press-forming apparatus according to the third embodiment.

[0027] Figure 7 This is a diagram schematically showing the relationship between a punch, a die, and a pressing member included in the press forming apparatus of the third embodiment when viewed from the press direction.

[0028] Figure 8 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in relation to a modification of the above-described embodiment.

[0029] Fig. 9 This is a diagram schematically showing the relationship among a punch, a die, and a pressing member when viewed from the punching direction in still another modified example of the above-described embodiment.

[0030] Fig.10 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in still another modified example of the above embodiment.

[0031] Fig.11 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in still another modified example of the above embodiment.

[0032] Fig.12 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in still another modified example of the above embodiment.

[0033] Fig.13 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in still another modified example of the above embodiment.

[0034] Fig.14 This is a diagram schematically showing the relationship among the punch, the die, and the pressing member when viewed from the punching direction in still another modified example of the above embodiment.

[0035] Fig.15 It is a schematic perspective view of a press forming device according to a modified example of the above-mentioned embodiment.

[0036] Fig.16 yes Fig.15 A cross-sectional view of the stamping device shown.

[0037] Fig.17This is a diagram in which the punch and die used in conventional stamping are projected onto a plane perpendicular to the stamping direction.

[0038] Fig.18 This is a diagram showing the analysis results of a case where the blank is pulled out from between the die and the pressing member and the forming is completed.

[0039] Fig.19 This is a diagram showing the analysis results of a case where the blank is sandwiched between the die and the pressing member and the forming is completed directly. DETAILED DESCRIPTION

[0040] Fig.17 This is a diagram of a punch 91 and a die 92 used in conventional stamping forming projected onto a plane perpendicular to the stamping direction. Fig.17 In the figure, arrow A1 indicates that when punching and forming are performed using punch 91 and die 92, the blank is pulled toward edge 921 of die 92 on the punch 91 side. When edge 921 of die 92 includes curved portion 921a and straight portions 921b provided on both sides of curved portion 921a, as in Fig.17 As indicated by the double arrow A2, the portion of the blank pulled toward the curved portion 921a is stretched in the extending direction of the curved portion 921a. On the other hand, the portion of the blank pulled toward each straight portion 921b does not substantially generate tensile stress along the extending direction of the straight portion 921b. Therefore, the blank is thinner at the curved portion 921a and thicker at the straight portion 921b. Fig.17 The dotted lines in the figure are examples of equal thickness lines of the blank during stamping. The equal thickness lines are lines connecting the parts of the blank during stamping where the plate thickness is equal. Fig.17 The figure shows that the thicker the isothickness line is, the thicker the sheet thickness of the blank is at that position.

[0041] If the blank is elongated and the thickness is reduced, cracks may occur in the portion of the blank where the thickness is reduced. As one of the methods for suppressing cracks in the blank, there can be cited a method of applying compressive stress in the thickness direction of the blank. In the present disclosure, a process for suppressing cracks in the blank by applying compressive stress in the thickness direction is referred to as a development process. The inventors of the present invention conceived of applying the development process in a case where the edge of the punch side of the die includes a bent portion, and completed a method for manufacturing a stamped product of an embodiment.

[0042] The manufacturing method of the stamped product of the embodiment comprises the steps of clamping the blank by the die and the pressing member and pressing the blank in the stamping direction by the punch. When viewed from the stamping direction, the edge of the die on the punch side includes a curved portion that is convexly curved toward the punch side and extends with a radius of curvature less than 400 mm. When viewed from the stamping direction, the interval between the edge of the pressing member on the punch side and the edge of the die on the punch side on the perpendicular line of the extension direction of the edge of the die changes along the edge of the die. When viewed from the stamping direction, the interval is smallest at the curved portion (the first structure).

[0043] As described above, when the edge of the die on the punch side includes a curved portion when viewed from the stamping direction, the thickness of the blank becomes thinner as the blank is pulled toward the curved portion during stamping. In contrast, in the first structure, when viewed from the stamping direction, the gap between the edge of the pressing member on the punch side and the edge of the die on the punch side is smallest at the curved portion. Therefore, by clamping the portion of the blank that is pulled toward the curved portion, that is, the portion with reduced thickness, near the curved portion using the die and the pressing member, compressive stress can be applied to the portion with reduced thickness in the direction of the plate thickness to the vicinity of the curved portion. Therefore, the generation of cracks in the blank can be suppressed during the process of manufacturing stamped products.

[0044] In the first structure, when viewed from the stamping direction, the interval between the edge of the pressing member on the punch side and the edge of the die on the punch side changes along the extension direction of the edge of the die. More specifically, at the edge of the die, the portion with the smallest interval with the edge of the pressing member is located at the bending portion, and at the portion other than this portion, the interval with the edge of the pressing member becomes larger. Therefore, during stamping, at the portion with the smallest interval between the edge of the pressing member and the edge of the die, the blank is pressed by the die and the pressing member until it reaches the vicinity of the edge of the die, and on the other hand, at the portion adjacent to this portion, the blank is not pressed until it reaches the vicinity of the edge of the die. Thus, during stamping, the material can flow into the plate thickness reduction portion of the blank, and the reduction in the plate thickness of the blank can be alleviated. Therefore, the generation of cracks in the blank can be further suppressed.

[0045] In the above-mentioned method for manufacturing a stamped product, when viewed from the stamping direction, the distance between the edge of the pressing member on the punch side and the edge of the die on the punch side may be larger as they are farther away from the bent portion (second configuration).

[0046] In the second structure, the interval between the edge of the pressing member and the edge of the die widens as they are away from the curved portion. Thus, the development process can be applied to the entire portion of the blank that is pulled in toward the curved portion, and the inflow of material into this portion can be promoted. That is, the interval between the edge of the pressing member and the curved portion of the edge of the die is smaller than the interval between the edge of the pressing member and the other portions of the edge of the die, and therefore, the die and the pressing member can be used to apply compressive stress in the thickness direction to the vicinity of the curved portion with respect to the entire portion of the blank that is pulled in toward the curved portion. On the other hand, the interval between the edge of the pressing member and the portion of the edge of the die other than the curved portion becomes larger as it is away from the curved portion, and therefore, the blank is pressed on both sides of the curved portion without reaching the vicinity of the edge of the die. Thus, the inflow of material relative to the portion of the blank that is pulled in toward the curved portion can be promoted.

[0047] In the manufacturing method of the stamped product, it is also possible that, when viewed from the stamping direction, the edge of the die on the punch side is composed only of a bent portion. In this case, it is also possible that, when viewed from the stamping direction, the interval between the edge of the punch side of the press component and the edge of the punch side of the die is the largest at the end of the bent portion (the third structure).

[0048] In the above-mentioned method for manufacturing a stamped product, it may be that, when observed from the stamping direction, the line length of a portion of the edge of the pressing part on the punch side where the distance from the edge of the die on the punch side is the smallest is greater than 0.5 times and less than 2.5 times the line length of the bent portion (the fourth structure).

[0049] A press forming device according to an embodiment includes a punch, a die, and a pressing member.

[0050] When viewed from the punching direction, the edge of the die on the punch side includes a curved portion that is convexly curved toward the punch side and extends with a radius of curvature less than 400 mm. When viewed from the punching direction, the interval between the edge of the punch side of the press component and the edge of the die on the punch side on a perpendicular line in the extending direction of the edge of the die changes along the edge of the die. When viewed from the punching direction, the interval is smallest at the curved portion (the fifth structure).

[0051] In the above-mentioned press forming device, when viewed from the press direction, the distance between the edge of the pressing member on the punch side and the edge of the die on the punch side may be larger as they are farther away from the bent portion (sixth configuration).

[0052] In the above-mentioned stamping forming device, it is also possible that, when viewed from the stamping direction, the edge of the die on the punch side is composed only of a curved portion. In this case, it is also possible that, when viewed from the stamping direction, the interval between the edge of the press member on the punch side and the edge of the die on the punch side is the largest at the end of the curved portion (the seventh structure).

[0053] In the above-mentioned stamping forming device, it may also be that, when observed from the stamping direction, the line length of the portion of the edge of the pressing part on the punch side where the distance between the edge of the die on the punch side is the smallest is greater than 0.5 times and less than 2.5 times the line length of the bending part (Structure 8).

[0054] Below, while referring to the attached Figure 1 In the drawings, the same or corresponding structures are denoted by the same reference numerals, and the same description will not be repeated.

[0055] <First embodiment>

[0056] [Press forming device]

[0057] Figure 1 1 is a schematic perspective view of a press forming device 100 according to the first embodiment. Figure 1 As shown in FIG. 1 , the press forming device 100 includes a punch 10, a die 20, and a pressing member 30. Figure 1 Only the die 20 located on one side relative to the imaginary line CL is shown, and the die 20 can also be arranged on both sides of the punch 10. These dies 20 can be separated or formed as one. In this embodiment, the space between these dies 20 is sometimes called a die hole. The pressing member 30 is set corresponding to the die 20.

[0058] The punch 10 and the pressing member 30 are configured to be relatively movable in the stamping direction P relative to the die 20. In the stamping forming device 100, the punch 10 and the pressing member 30 can be moved in the stamping direction P, and the die 20 can also be moved in the stamping direction P by using a driving mechanism such as a fluid pressure cylinder (not shown in the figure). The pressing member 30 can be relatively moved in the stamping direction P relative to the punch 10 by using a driving mechanism such as a buffer (not shown in the figure). The stamping direction P is, for example, a vertical direction, but is not particularly limited. If the stamping direction P is a vertical direction, it is easy to move the blank 200 ( Figure 4A ) is placed between the punch 10 and the die 20.

[0059] Figure 2 yes Figure 1 The cross-sectional view of the stamping device 100 shown in FIG. The cross-sectional view of the stamping device 100 refers to the cross-sectional view when the stamping device 100 is cut along a plane parallel to the stamping direction P and perpendicular to the length direction of the punch 10. In the cross-sectional view of the stamping device 100, the direction perpendicular to the stamping direction P is referred to as the width direction of the stamping device 100. Figure 2 In, with Figure 1Likewise, only a portion of the press forming device 100 located on one side with respect to the imaginary line CL is shown. The imaginary line CL is, for example, a center line of the press forming device 100 in the width direction.

[0060] Reference Figure 2 The punch 10 includes a punch top surface 11 , a punch shoulder 12 , and a punch side surface 13 .

[0061] The punch top surface 11 is a surface intersecting the punching direction P. The punch top surface 11 may also be perpendicular to the punching direction P. The punch top surface 11 substantially extends in the width direction when the punch forming device 100 is observed in cross section. The punch shoulder 12 is continuous with the end of the punch top surface 11. The punch shoulder 12 substantially has an arc shape when the punch forming device 100 is observed in cross section. The reason is that if the punch shoulder 12 is sharp, it is possible to cut the blank 200 ( Figure 4A ). The radius of curvature of the punch shoulder 12 may also be greater than 1.0 mm. The punch side surface 13 is connected to the punch top surface 11 via the punch shoulder 12. The punch side surface 13 extends from the punch shoulder 12 in the punching direction P when the punch forming device 100 is observed in a cross section. When the punch forming device 100 is observed in a cross section, the punch side surface 13 may be parallel to the punching direction P or may be inclined relative to the punching direction P.

[0062] The die 20 includes a pressing surface 21, a die shoulder 22, and a die side surface 23. The pressing surface 21 of the die 20 is, for example, a flat surface substantially perpendicular to the stamping direction P. The die shoulder 22 is continuous with the end of the pressing surface 21 on the punch 10 side when viewed in cross section of the stamping forming device 100. The die shoulder 22 is, for example, substantially in the shape of an arc when viewed in cross section of the stamping forming device 100. The reason for this is that if the die shoulder 22 is sharp, it is possible that the blank 200 ( Figure 4A ). The radius of curvature of the die shoulder 22 may also be greater than 1.0 mm. The die side surface 23 is connected to the pressing surface 21 via the die shoulder 22. The die side surface 23 extends from the die shoulder 22 in the stamping direction P when the stamping forming device 100 is observed in a cross section. The die side surface 23 has a shape corresponding to the punch side surface 13.

[0063] The pressing member 30 is arranged outside the punch 10 in the width direction of the press forming device 100 . The pressing member 30 is arranged to face the die 20 in the pressing direction P. The pressing member 30 includes a pressing surface 31 , a pressing member shoulder 32 , and a pressing member side surface 33 .

[0064] The pressing surface 31 of the pressing member 30 is opposite to the pressing surface 21 of the die 20 in the stamping direction P. The pressing surface 31 is, for example, a flat surface substantially perpendicular to the stamping direction P. The pressing member shoulder 32 is continuous with the end of the pressing surface 31 on the punch 10 side when observed in the cross section of the stamping forming device 100. The pressing member side surface 33 is connected to the pressing surface 31 via the pressing member shoulder 32. The pressing member side surface 33 extends from the pressing member shoulder 32 in the stamping direction P when observed in the cross section of the stamping forming device 100. The pressing member side surface 33 is opposite to the punch side surface 13 in the width direction of the stamping forming device 100.

[0065] The press forming device 100 may have a symmetrical shape or an asymmetrical shape with respect to the width center line CL when viewed in cross section.

[0066] Figure 3 Schematically shows the relationship between the punch 10, the die 20, and the pressing member 30 when viewed from the punching direction P. In other words, Figure 3 Schematic diagram showing the punch 10, the die 20, and the pressing member 30 when projected onto a plane perpendicular to the punching direction P. Figure 3 In FIG. 1 , the edge 24 of the die 20 is indicated by a solid line, and the edge 34 of the pressing member 30 is indicated by a dotted line. In order to easily distinguish the die 20 and the pressing member 30, the pressing member 30 is given a hatching line. Figure 3 In FIG. 1 , the edge 14 of the punch 10 is indicated by a dashed line. Figure 3 The edge 14 of the punch 10 in FIG. 1 is a portion of the punch side surface 13 that is located on the same plane as the pressing surface 21 of the die 20 .

[0067] Reference Figure 3 When viewed from the stamping direction P, the edge 14 of the punch 10 on the die 20 side extends along the edge 24 of the die 20 on the punch 10 side. The edge 24 of the die is a die shoulder 22. The edge 14 of the punch 10 has a shape corresponding to the edge 24 of the die 20. For example, when viewed from the stamping direction P, the edge 14 of the punch 10 is substantially parallel to the edge 24 of the die 20 as a whole. The gap between the edge 14 of the punch 10 and the edge 24 of the die 20 when viewed from the stamping direction P is greater than the plate thickness of the blank as the raw material for stamping so as not to hinder the relative movement of the punch 10 and the die 20 in the stamping direction P. When viewed from the stamping direction P, the edge 24 of the die 20 includes a curved portion 241 and straight portions 242 and 243.

[0068] The curved portion 241 is curved convexly toward the punch 10 side when viewed from the stamping direction P. The curved portion 241 extends with a radius of curvature less than 400 mm when viewed from the stamping direction P. The curved portion 241 may have a constant radius of curvature, or the radius of curvature may vary. In the present disclosure, when viewed from the stamping direction P, for each point on the edge 24 of the die 20 arranged at intervals of 5.0 mm, the radius of curvature of the arc passing through the point and the points on both sides of the point is measured, and the section with a radius of curvature less than 400 mm is regarded as the curved portion 241, and the section with a radius of curvature greater than 400 mm is regarded as a non-curved portion (straight portion).

[0069] The straight portions 242 and 243 are continuously provided at both ends of the curved portion 241. The straight portions 242 and 243 extend from the curved portion 241 so as to become more distant from each other as they are away from the curved portion 241, as viewed from the punching direction P. The straight portions 242 and 243 may be located on tangent lines at both ends of the curved portion 241, as viewed from the punching direction P.

[0070] The pressing member 30 is provided, for example, in a manner corresponding to only a portion of the edge 24 of the die 20. The pressing member 30 is arranged at a position corresponding to the curved portion 241 of the edge 24 of the die 20 when viewed from the punching direction P. In the present embodiment, the pressing member 30 has a shape that becomes substantially tapered toward the punch 10 when viewed from the punching direction P. Figure 3 In the example shown, the pressing member 30 has a substantially triangular shape as viewed in the punching direction P.

[0071] When viewed from the stamping direction P, the interval C between the edge 34 of the pressing member 30 on the punch 10 side and the edge 24 of the die 20 changes along the edge 24 of the die 20. That is, the interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 is not constant over the entire length of the edge 34 of the pressing member 30. The interval C is the interval between the edge 34 of the pressing member 30 and the edge 24 of the die 20 on a perpendicular line in the extension direction of the edge 24 of the die 20 when viewed from the stamping direction P. In other words, the interval C is the distance from the edge 34 of the pressing member 30 to the edge 24 of the die 20 in the normal direction of the curved portion 241 or the perpendicular direction of the straight portions 242 and 243 as viewed from the stamping direction P. The perpendicular line in the extension direction of the edge 24 of the die 20 refers to the distance from the edge 34 of the pressing member 30 to the edge 24 of the die 20 relative to the die shoulder 22 ( Figure 2 ) is perpendicular to or normal to the edge of the punch 10 side. The perpendicular to the extending direction of the edge 24 of the die 20 is perpendicular to the edge 24 of the punch 10 side when using the stamping forming device 100 ( Figure 1 and Figure 2 ) and the direction in which the blank is pulled into the die hole is roughly the same when the blank is formed. The edge 34 of the pressing member 30 is the shoulder 32 of the pressing member when viewed from the punching direction P ( Figure 2 ) on the edge of the punch 10 side.

[0072] When viewed from the punching direction P, the interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 is the smallest at the bend 241. That is, from the punching direction P, if the position of the edge 24 of the die 20 where the interval between the edge 34 of the pressing member 30 is the smallest is selected and a vertical line of the edge 24 of the die 20 is drawn, the vertical line passes through the bend 241. The minimum value of the interval C is, for example, smaller than the gap between the edge 14 of the punch 10 and the edge 24 of the die 20. The minimum value of the interval C can also be 0 mm. When the minimum value of the interval C is 0 mm, when viewed from the punching direction P, the edge 34 of the pressing member 30 overlaps with the edge 24 of the die 20 at the position where the edge 34 of the pressing member 30 is closest to the edge 24 of the die 20, and at other positions, the edge 24 of the die 20 is arranged on the punch 10 side relative to the edge 34 of the pressing member 30. When the minimum value of the interval C is greater than 0 mm, the edge 34 of the pressing member 30 is entirely disposed on the side opposite to the punch 10 with respect to the edge 24 of the die 20 when viewed in the punching direction P.

[0073] As viewed from the stamping direction P, the line length of the portion of the edge 34 of the pressing member 30 where the interval C with the edge 24 of the die 20 is the smallest can be set, for example, to be greater than 0.5 times and less than 2.5 times the line length of the curved portion 241. The line length of the curved portion 241, that is, the length in the extension direction of the curved portion 241 can be set to the product of the angle θ (rad) and the radius of curvature of the curved portion 241. The angle θ is the angle formed by the tangents at both ends of the curved portion 241 as viewed from the stamping direction P. The angle θ can also be greater than 1 / 3π (rad) and less than 2 / 3π (rad). In the case where the radius of curvature of the curved portion 241 changes, the radius of curvature of the curved portion 241 can be set, for example, to the average value of the radius of curvature measured at 5.0 mm intervals as described above.

[0074] exist Figure 3 In the example shown, when viewed from the stamping direction P, the interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 is the smallest at the top of the curved portion 241 protruding toward the punch 10. The interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 increases as they are away from the top of the curved portion 241. That is, the interval C changes within the range of the curved portion 241. The interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 further increases at the straight portions 242 and 243 on both sides of the curved portion 241. When viewed from the stamping direction P, the interval C increases as it is away from the curved portion 241.

[0075] [Manufacturing method of stamped product]

[0076] Next, use Figure 4A to Figure 4FNext, a method for producing a press-formed product using the press-forming apparatus 100 will be described.

[0077] Reference Figure 4A , when manufacturing a stamped product, first, prepare a blank 200. For example, the blank 200 can be obtained by blanking a rolled steel plate. The blank 200 is formed, for example, into a shape obtained by unfolding the target stamped product. The shape obtained by unfolding the target stamped product can be obtained by using, for example, a finite element analysis software for analyzing stamping, which derives the shape of the blank before forming from the shape of the formed product. The blank 200 may also be a steel plate. The blank 200 is preferably a high-strength steel plate. The tensile strength of the blank 200 is, for example, more than 440 MPa. The tensile strength of the blank 200 may be more than 590 MPa, or more than 780 MPa. The tensile strength of the blank 200 may also be more than 980 MPa, or more than 1180 MPa, or more than 1300 MPa. The plate thickness of the blank 200 may be, for example, more than 0.4 mm and less than 6.0 mm, or more than 1.0 mm and less than 4.0 mm.

[0078] The method for manufacturing a press-formed product includes a step of sandwiching a blank 200 between the die 20 and the pressing member 30 , and a step of pressing the blank 200 in a press direction P with the punch 10 .

[0079] Reference Figure 4B First, the blank 200 is placed between the punch 10 and the pressing member 30 and the die 20. For example, the blank 200 is placed on the punch top surface 11 and the pressing surface 31 of the pressing member 30. Alternatively, the blank 200 may be placed on the pressing surface 21 ( Figure 2 ). Then, if Figure 4C As shown, the pressing member 30 and the die 20 are brought relatively close to each other in the punching direction P, and the blank 200 is sandwiched and pressed by the pressing surface 21 of the die 20 and the pressing surface 31 of the pressing member 30 .

[0080] Reference Figure 4D , the blank 200 is held between the die 20 and the pressing member 30, and the die 20 and the punch 10 are brought relatively close in the punching direction P. Thus, the blank 200 is pressed toward the die 20 side (die hole) by the punch 10. As the punch 10 presses in, the blank 200 is pulled toward the die hole. Figure 4D In the figure, the direction in which the blank 200 is pulled in is indicated by arrow D. In the example of the present embodiment, the pressing (forming) by the punch 10 is completed after the blank 200 is completely pulled out from between the die 20 and the pressing member 30. Figure 4FAs shown, the forming can also be completed while the blank 200 is partially clamped by the die 20 and the pressing member 30.

[0081] When the punch 10 is pressed into place, the blank 200 is formed into, for example, Figure 4E The stamped product 300 shown in FIG. The stamped product 300 includes a top plate 301 , a ridge portion 302 , and a flange 303 .

[0082] exist Figure 4E In the example shown, when viewed from the vertical direction of the top plate 301 of the stamped product 300, a portion that is recessed inward in the width direction is provided at the side edge of the top plate 301. The top plate 301 is formed in a manner that the width of the central portion in the length direction is smaller than the width of the two ends in the length direction. That is, the top plate 301 is formed in a shape in which the central portion in the length direction is necked inward when viewed from above. The top plate 301 may also have a flat shape as a whole, or may have a concave-convex shape in a part thereof. A through hole may also be formed in the top plate 301.

[0083] A ridge portion 302 is continuously provided at the side edge in the width direction of the top plate 301. The flange 303 is connected to the side edge of the top plate 301 via the ridge portion 302. The flange 303 is continuous with the ridge portion 302 and is provided in a manner of standing from the top plate 301. The ridge portion 302 and the flange 303 extend along the side edge of the top plate 301.

[0084] The tensile strength of the stamped product 300 is, for example, 440 MPa or more. The tensile strength of the stamped product 300 may be 590 MPa or more, or 780 MPa or more. The tensile strength of the stamped product 300 may be 980 MPa or more, or 1180 MPa or more, or 1300 MPa or more. The plate thickness of the stamped product 300 may be, for example, 0.4 mm or more and 6.0 mm or less, or 1.0 mm or more and 4.0 mm or less.

[0085] The stamped product 300 can be used as an automobile part, for example. The stamped product 300 can also be a body part, a chassis part, or a panel part of an automobile. As a body part, for example, side beams, roof longitudinal beams, front pillars, center pillars, door lock pillars, kick reinforces, longitudinal members, etc. can be listed. Chassis parts are, for example, arm parts or connecting rod parts of a suspension. As arm parts or connecting rod parts, for example, sub-frames, lower arms, upper arms, trailing arms, etc. can be listed. As panel parts, door inner panels, side panels, floors, etc. can be listed.

[0086] If the development process is used, processing marks such as pressing marks or friction marks remain at the part of the stamped product 300 where the pressing member 30 is partially pressed. These processing marks do not have a negative impact on the mechanical properties of the stamped product. Figure 4E In the stamped product 300 , processing marks remain on the back side of the flange 303 that is not exposed in the figure.

[0087] [Effect]

[0088] The present embodiment relates to the following development process: when deep drawing is performed using a die 20 including a curved portion 241 on the edge 24 near the punch 10 side, a compression stress is applied to the plate thickness reduction portion generated in the blank 200 by a pressing member 30 to suppress cracks in the blank 200. Specifically, when the blank 200 is pressed into the die hole by the punch 10 to perform forming, the blank 200 is pulled toward the curved portion 241 of the edge 24 near the punch 10 side of the die 20. The portion of the blank 200 pulled toward the curved portion 241 is elongated in the extension direction of the curved portion 241 as it is pulled into the curved portion 241, and its plate thickness is reduced. In contrast, the stamping forming device 100 of the present embodiment is configured in such a way that the interval C between the edge 34 near the punch 10 side of the pressing member 30 and the edge 24 near the punch 10 side of the die 20 is the smallest at the curved portion 241 when viewed from the stamping direction P. Therefore, the portion of the blank 200 that is pulled toward the curved portion 241 and has a reduced thickness can be clamped near the curved portion 241 by the punch 20 and the press member 30 to apply compressive stress in the thickness direction. Thus, in the process of manufacturing the stamped product 300, the generation of cracks in the blank 200 can be suppressed.

[0089] From the perspective of developing the process, it is desirable that when the blank 200 is formed into the stamped product 300, the blank 200 pulled toward the bent portion 241 is pressed by the die 20 and the pressing member 30 until it reaches the vicinity of the bent portion 241. On the other hand, from the perspective of the inflow of the material, if the die 20 and the pressing member 30 are not used to press the periphery of the plate thickness reduction portion of the blank 200, the material flows into the plate thickness reduction portion of the blank 200, and the reduction of the plate thickness of the blank 200 can be alleviated. Therefore, in the present embodiment, from the perspectives of developing the process and the inflow of the material, the interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 is changed along the extension direction of the edge 24 of the die 20. That is, when viewed from the stamping direction P, the edge 34 of the pressing member 30 extends along the edge 24 of the die 20, but is not parallel to the edge 24 of the die 20. From the perspective of the stamping direction P, the interval C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 is the smallest at a part of the curved portion 241 and becomes larger at other parts. Thus, during stamping, the blank 200 is pressed by the die 20 and the pressing member 30 to the vicinity of the edge 24 of the die 20 at the location where the interval C is the smallest, and on the other hand, the blank 200 is not pressed to the vicinity of the edge 24 of the die 20 at the location adjacent to the location. Therefore, compressive stress can be applied to the reduced thickness portion of the blank 200 in the thickness direction, and material can flow in. Therefore, when deep drawing is performed using the die 20 whose edge 24 on the punch 10 side includes the curved portion 241, the generation of cracks in the blank 200 can be suppressed.

[0090] For the portion of the blank 200 that is pulled into the curved portion 241, especially when there is a portion where the plate thickness is drastically reduced, the edge 24 of the die 20 and the edge 34 of the press member 30 can be brought closest to each other at the portion where the plate thickness is drastically reduced. For example, as in the present embodiment, the interval C between the edge 34 of the press member 30 and the edge 24 of the die 20 can be set to the minimum at the top of the curved portion 241 that protrudes toward the punch 10 side. In this case, compressive stress can be applied to the portion where the plate thickness is drastically reduced in the blank 200 in the plate thickness direction, and the inflow of material can be promoted. Therefore, the reduction in the plate thickness of the blank 200 can be efficiently mitigated, and cracks in the blank 200 can be effectively suppressed.

[0091] In this embodiment, when viewed from the punching direction P, the distance C between the edge 34 of the pressing member 30 and the edge 24 of the die 20 increases as they are farther from the curved portion 241. Thus, compared with the portion of the blank 200 pulled into the straight portions 242 and 243, the entire portion of the blank 200 pulled into the curved portion 241 can be pressed by the pressing member 30 until near the die hole, and the material can be promoted to flow into the portion pulled into the curved portion 241 from the periphery thereof.

[0092] In this embodiment, when viewed from the punching direction P, the line length of the portion of the edge 34 of the pressing member 30 where the interval C between the edge 24 of the die 20 is the smallest is preferably 0.5 times or more and 2.5 times or less the line length of the bent portion 241. Thus, cracks in the blank 200 can be effectively suppressed.

[0093] <Second embodiment>

[0094] Figure 5 1 is a diagram relating to a press forming apparatus 100A according to the second embodiment, and schematically shows the relationship between the punch 10 , the die 20 , and the pressing member 30A when viewed from the press direction P. In other words, Figure 5 Schematic diagram showing the punch 10, the die 20, and the pressing member 30A when projected onto a plane perpendicular to the punching direction P. Figure 5 In FIG. 1 , the edge 24 of the die 20 is indicated by a solid line, and the edge 34 of the pressing member 30A is indicated by a dotted line. In order to easily distinguish the die 20 and the pressing member 30A, the pressing member 30A is given a hatching line. Figure 5 In FIG. 1 , the edge 14 of the punch 10 is indicated by a dashed line. Figure 5 The edge 14 of the punch 10 in FIG. 1 is a portion of the punch side surface 13 that is located on the same plane as the pressing surface 21 of the die 20 .

[0095] The press forming device 100A of the present embodiment has the same features as the press forming device 100 ( Figure 1 to Figure 3 ) is basically the same structure. However, the press forming device 100A of this embodiment includes a press member 30A different from the press forming device 100 of the first embodiment.

[0096] like Figure 5 As shown, the pressing member 30A is provided in the same manner as the first embodiment, for example, corresponding to only a portion of the edge 24 of the die 20. The pressing member 30A is arranged at a position corresponding to the curved portion 241 of the edge 24 of the die 20 when viewed from the punching direction P.

[0097] When viewed from the punching direction P, the interval C between the edge 34 of the press member 30A on the punch 10 side and the edge 24 of the die 20 on the punch 10 side on the vertical line of the extension direction of the edge 24 of the die 20 changes along the edge 24 of the die 20. In the present embodiment, the curved portion 241 of the edge 24 of the die 20 is substantially parallel to the edge 34 of the press member 30A. That is, within the range of the curved portion 241, the interval C between the edge 34 of the press member 30A and the edge 24 of the die 20 is substantially constant. On the other hand, from the punching direction P, the straight portions 242 and 243 adjacent to the curved portion 241 in the edge 24 of the die 20 are not parallel to the edge 34 of the press member 30A. The interval C between the edge 34 of the press member 30A and the straight portions 242 and 243 is larger as it is away from the curved portion 241.

[0098] Even the pressing member 30A in this embodiment can achieve the same effect as that of the first embodiment. In this embodiment, when viewed from the stamping direction P, the interval C between the edge 34 of the pressing member 30A and the edge 24 of the die 20 is the smallest at the curved portion 241, and is substantially constant at the entire curved portion 241. Therefore, during stamping, the entire portion of the blank that is pulled into the curved portion 241 can be pressed by the die 20 and the pressing member 30A until near the edge 24 of the die 20. On the other hand, in the straight portions 242 and 243 adjacent to the curved portion 241, the interval C between the edge 34 of the pressing member 30A and the edge 24 of the die 20 increases as it moves away from the curved portion 241. Therefore, during stamping, the portion of the blank that is pulled into the straight portions 242 and 243 is not pressed by the pressing member 30A near the edge 24 of the die 20. Therefore, it is possible to promote the flow of material from the portion of the blank drawn into the straight portions 242 and 243 to the portion drawn into the curved portion 241. As a result, when deep drawing is performed using the die 20 including the curved portion 241 at the edge 24 on the punch 10 side, the generation of cracks in the blank can be suppressed.

[0099] <Third embodiment>

[0100] Figure 6 is a schematic representation of Figure 4E The stamped product 300 shown is a perspective view of a stamped product 400 which is different from the stamped product 300. The stamped product 400 is, for example, a suspension arm component of an automobile.

[0101] like Figure 6As shown, the stamped product 400 includes a top plate 401, ridges 402, 403, 404, and flanges 405, 406, 407. The flange 405 is connected to the end edge of the top plate 401 via the ridge 402. The flange 406 is connected to the other end edge of the top plate 401 via the ridge 403. The flange 407 is connected to another end edge of the top plate 401 via the ridge 404. The flanges 405, 406, 407 are respectively continuous with the ridges 402, 403, 404, and are provided in a manner of standing up from the top plate 401.

[0102] exist Figure 6 In the example shown, the ridge portion 402 and the flange 405 are curved as a whole when viewed from above in a direction perpendicular to the top plate 401 of the press-formed product 400 . Figure 7 The figure is related to the press forming apparatus 100B for forming the press formed product 400 including such a ridge line portion 402 and a flange 405 . Figure 7 The figure schematically shows the relationship between the punch 10B, the die 20B, and the pressing member 30B when the punching device 100B is viewed from the punching direction P. Figure 7 In FIG. 1 , the edge 24 of the die 20B is indicated by a solid line, and the edge 34 of the pressing member 30B is indicated by a dotted line. In order to easily distinguish the die 20B and the pressing member 30B, the pressing member 30B is given a hatching line. Figure 7 In FIG. 1 , the edge 14 of the punch 10B is indicated by a dashed line. Figure 7 The edge 14 of the punch 10 in FIG. 1 is a portion of the punch side surface 13 that is located on the same plane as the pressing surface 21 of the die 20 .

[0103] Reference Figure 7 When viewed from the stamping direction P, the edge 14 of the punch 10B on the die 20B side extends along the edge 24 of the die 20B on the punch 10B side. When viewed from the stamping direction P, the edge 14 of the punch 10B has a shape corresponding to the edge 24 of the die 20B. When viewed from the stamping direction P, the edge 24 of the die 20B is composed only of a bent portion 241. That is, when viewed from the stamping direction P, the edge 24 of the die 20B is curved convexly toward the punch 10B side as a whole, and extends with a radius of curvature less than 400 mm. The edge 24 of the die 20B may have a constant radius of curvature, or the radius of curvature may vary.

[0104] As viewed from the punching direction P, the interval C between the edge 34 of the press member 30B on the punch 10B side and the edge 24 of the die 20B on the punch 10B side is smaller on the central side and larger on the end side along the extension direction of the curved portion 241. The interval C may also gradually widen toward the end of the extension direction of the curved portion 241. When viewed from the punching direction P, the interval C is the largest at the end of the extension direction of the curved portion 241. The interval C is, for example, the smallest at a portion of the curved portion 241 where the thickness of the blank is drastically reduced during stamping.

[0105] From the punching direction P, the edge 34 of the press member 30B is, for example, arranged in a manner corresponding only to the part of the edge 24 of the die 20B. In the present embodiment, the edge 24 of the die 20B is composed of only the curved portion 241, so from the punching direction P, when the vertical line (normal line) of the end of the curved portion 241 is drawn, the vertical line sometimes does not intersect with the press member 30B. In this case, when observed from the punching direction P, the interval C between the end of the curved portion 241 and the edge 34 of the press member 30B, in the direction of the vertical line of the curved portion 241, becomes infinite. In this case, it can also be said that the interval C is the largest at the end of the curved portion 241.

[0106] As in the present embodiment, even when the edge 24 of the die 20B is composed only of the curved portion 241 when viewed from the stamping direction P, the interval C between the edge 34 of the pressing member 30B and the edge 24 of the die 20B can be narrowed at a part of the curved portion 241, thereby achieving the same effect as that of the first embodiment. That is, for the blank pulled into the curved portion 241 during stamping, especially when there is a portion where the plate thickness is drastically reduced, by bringing the edge 24 of the die 20B and the edge 34 of the pressing member 30B closest to each other at the portion where the plate thickness is drastically reduced, compressive stress can be applied to the portion where the plate thickness is drastically reduced in the plate thickness direction, and material inflow can be promoted. Therefore, when deep drawing is performed using the die 20B in which the edge 24 on the punch 10B side is composed only of the curved portion 241, the generation of cracks in the blank can be suppressed.

[0107] In this embodiment, the pressing member 30B has the same shape as the pressing member 30 ( Figure 3 ) is substantially the same shape. However, the pressing member 30B may also have the same shape as the pressing member 30A ( Figure 5 ) has the same shape.

[0108] As mentioned above, although embodiment of this disclosure was described, this disclosure is not limited to the said embodiment, Various changes are possible as long as they do not deviate from the summary.

[0109] In the manufacturing method and the stamping forming device of the present embodiment, the press parts 30, 30A, and 30B described in the above embodiment are not limited, and press parts of various shapes can be used. The press part is a shape in which the interval between the edge of the press part on the punch side and the edge of the die on the punch side changes along the edge of the die on the punch side when viewed from the stamping direction P, and is the smallest at the curved portion.

[0110] For example, being able to use Figure 8 The pressing member 30C shown is used to replace Figure 3 The pressing member 30 or Figure 5 The pressing member 30A shown. Figure 8 As shown, the pressing member 30C has a shape that is generally tapered as it moves away from the punch 10 when viewed from the punching direction P. However, the situation of the pressing member 30C is the same as that of the pressing members 30 and 30A. When viewed from the punching direction P, the interval C between the edge 34 of the pressing member 30C and the edge 24 of the die 20 is the smallest at the curved portion 241. The interval C increases as it moves toward the two ends of the extending direction of the curved portion 241 as viewed from the punching direction P. The interval C also increases as it moves away from the curved portion 241.

[0111] For example, you can also use Fig. 9 The pressing member 30D shown in the figure replaces the pressing members 30 and 30A. Fig. 9 As shown, when viewed from the punching direction P, the interval C between the edge 34 of the pressing member 30D and the edge 24 of the die 20 is smallest at the curved portion 241. As viewed from the punching direction P, the edge 34 of the pressing member 30D is substantially parallel to the middle portion of the curved portion 241. The interval C between the edge 34 of the pressing member 30D and the edge 24 of the die 20 increases as it is further away from the curved portion 241.

[0112] For example, you can also use Fig.10 The pressing member 30E shown, Fig.11 The pressing member 30F shown, or Fig.12 The pressing member 30G shown replaces the pressing members 30 and 30A. Figure 10 to Figure 12 As shown, when viewed from the punching direction P, the edges 34 of the respective pressing members 30E, 30F, and 30G are substantially parallel to the entire curved portion 241. Compared with the curved portion 241, the interval C between the edges 34 of the respective pressing members 30E and 30F and the edge 24 of the die 20 is larger at the straight portions 242 and 243. The interval C increases as it is further away from the curved portion 241. The interval C between the edge 34 of the pressing member 30G and the edge 24 of the die 20 increases sharply (becomes infinitely large) at certain points P1 and P2.

[0113] As in the third embodiment, the pressing members 30C to 30G can also be applied to a case where the edge 24 of the die 20B on the punch 10B side is composed only of the bent portion 241 .

[0114] In the above-mentioned embodiments and Figure 8 to Figure 12 In the example shown, the pressing members 30, 30A to 30G have a shape symmetrical with respect to a perpendicular line (normal line) of the top of the curved portion 241 when viewed from the punching direction P. However, the pressing members 30, 30A to 30G do not necessarily need to have a symmetrical shape when viewed from the punching direction P. The edge 34 of each pressing member 30, 30A to 30G only needs to be closest to the edge 24 of the die 20B at least partially in the curved portion 241, and does not necessarily need to be closest to the edge 24 of the die 20 or the die 20B at the top of the curved portion 241.

[0115] For example Fig.13 As shown, for a pressing member 30H extending substantially over the entire edge 24 of the die 20 on the punch 10 side, the protrusion 35 can be provided on the surface thereof opposite to the die 20 or the die 20B along the stamping direction P. In this case, the edge of the protrusion 35 on the punch 10 side when viewed from the stamping direction P can be regarded as the edge 34 of the pressing member 30H. That is, as viewed from the stamping direction P, the interval C between the edge of the protrusion 35 on the punch 10 side and the edge 24 of the die 20 on the punch 10 side on a perpendicular line in the extension direction of the edge 24 of the die 20 changes along the edge 24 of the die 20, and is smallest at the bend 241. Thus, the same effects as those of the above-mentioned embodiment can be achieved. Fig.13 In the example of the embodiment, the convex portion 35 has the same shape as the shape of the pressing member 30 in the first embodiment when viewed from the punching direction P. However, the shape of the convex portion 35 is not limited thereto. For example, the convex portion 35 may also have the same shape as any one of the pressing members 30A to 30G when viewed from the punching direction P.

[0116] The shape of the pressing members 30, 30A to 30G can be appropriately changed according to the relationship between the shape of the edge of the die on the punch side and the position in the blank where the plate thickness is drastically reduced. For example, a pressing member that is rectangular or trapezoidal in shape as viewed from the punching direction P can be used instead of the pressing members 30, 30A to 30G. The pressing member can also be, for example, semicircular or semi-elliptical in shape as viewed from the punching direction P. However, the pressing member is constructed in such a way that the edge of the pressing member on the punch side and the edge of the die on the punch side as viewed from the punching direction P are closest to each other in part or all of the curved portion.

[0117] In the case of modifying an existing stamping forming device and implementing the manufacturing method of the stamping formed product disclosed in the present invention, a plate can also be provided on the pressing plate surface of the pressing member provided in the existing stamping forming device. In the existing stamping forming device, when observed from the stamping direction, the edge of the pressing member on the punch side is opposite to the edge of the punch side of the die, and the interval between the edge of the pressing member and the edge of the die is constant. In such an existing stamping forming device, a plate is provided on the pressing plate surface of the pressing member. Thus, the edge of the plate on the punch side when observed from the stamping direction can be regarded as the edge of the pressing member. From the stamping direction, the interval between the edge of the plate on the punch side and the edge of the die on the punch side on the vertical line of the extension direction of the edge of the die changes along the edge of the die, and is the smallest at the bending portion. Thus, the same effect as that of the above-mentioned embodiment can be achieved. In addition, the plate can also be replaced by cutting the pressing plate surface of the pressing member to form a convex portion. In this case, the edge of the convex portion formed on the pressing plate surface of the pressing member can be regarded as the edge of the pressing member.

[0118] In the above-mentioned first embodiment, an example is described in which the die 20 and the pressing member 30 are provided on both sides of the punch 10 along the width direction of the stamping forming device 100. However, the die 20 and the pressing member 30 may be provided only on one side of the punch 10 along the width direction of the stamping forming device 100. Alternatively, it is also possible to provide the pressing member 30 on one side of the punch 10 and any one of the pressing members 30A to 30G on the other side along the width direction of the stamping forming device 100. The number and position of the pressing members can be appropriately changed according to, for example, the number and position of the bending portions 241. In addition, in the stamping forming device of the present disclosure, for example Fig.14 As shown, when viewed from the punching direction P, the pressing members 41 and 42 that are separate from the pressing member 30E can also be provided adjacent to the pressing member 30E whose edge 34 on the punch 10 side is closest to the edge 24 on the punch 10 side of the die 20 at the bent portion 241. Fig.14 In the example, the pressing members 41 and 42 are arranged on both sides of the pressing member 30E when viewed from the stamping direction P. Even in this case, the pressing member 30E and the pressing members 41 and 42 act independently, so the reduced thickness portion of the blank 200 that is pulled toward the curved portion 241 of the edge 24 of the die 20 can be pressed by the pressing member 30E until near the curved portion 241. Fig.14 In the embodiment, as a material pressing member for pressing the blank 200 pulled toward the curved portion 241, a material pressing member 200 is shown. Fig.10 Similarly, when using other pressing members such as the pressing members 30E, 30A to 30D, 30F to 30G, etc., the pressing members 41 and 42 which are separate from these pressing members can also be provided.

[0119] like Fig.15 and Fig.16 As shown, the stamping forming device 100 of the first embodiment may also include a pressure plate 50 opposite to the punch 10 in the stamping direction P. In the process of manufacturing a stamped product, the pressure plate 50 can be relatively close to the punch 10 in the stamping direction P to press the blank 200 on the punch 10. Similarly, the stamping forming devices 100A and 100B of other embodiments may also include a pressure plate 50.

[0120] Example

[0121] Hereinafter, the present disclosure will be described in further detail using examples, but the present disclosure is not limited to the following examples.

[0122] When the interval where the edge of the punch side of the die is closest to the edge of the punch side of the press member when viewed from the stamping direction is an extremely short interval, it is believed that the effect described in the above embodiment is less different from the case where the bending forming without the press member is performed. On the other hand, when the interval where the edge of the punch side of the die is closest to the edge of the punch side of the press member when viewed from the stamping direction is an extremely long interval, it is believed that the difference in effect between the case where the usual deep drawing forming is performed is less. Therefore, the inventors of the present invention implemented stamping forming analysis and studied the appropriate length of the interval with the smallest interval between the edge of the punch side of the die and the edge of the press member on the punch side.

[0123] The inventors of the present invention set it to be described as the ratio of the length of the interval where the interval between the edge of the die on the punch side and the edge of the pressing part on the punch side is the shortest as viewed from the stamping direction, (line length), to the extension length (line length) of the bent portion included in the edge of the die on the punch side.

[0124] In this analysis, it is assumed that the curved portion of the edge of the die when observed from the punching direction extends with a constant radius of curvature. The extended length (line length) of the curved portion is set as the product of the angle (angle θ (rad)) formed by the intersection of the tangents at the two ends of the curved portion and the radius of curvature of the curved portion. If the length of the interval with the smallest spacing between the edge of the die on the punch side and the edge of the pressing member on the punch side (line length) / the line length of the curved portion is less than 1.0, it means that the edge of the die and the edge of the pressing member are closest to each other in a part of the curved portion. If the length of the interval with the smallest spacing between the edge of the die on the punch side and the edge of the pressing member on the punch side (line length) / the line length of the curved portion is 1.0, it means that the edge of the die and the edge of the pressing member are closest to each other in the entire curved portion. If the length of the interval with the smallest interval between the edge of the die on the punch side and the edge of the pressing member on the punch side (line length) / the line length of the curved portion is greater than 1.0, it means that the edge of the die and the edge of the pressing member are closest to each other in the entire curved portion and the part of the straight portion adjacent to the curved portion.

[0125] The inventors described the magnitude of damage at the edge of the flange of the stamped product after forming using the damage value I represented by the following formula. In addition, the inventors evaluated the magnitude of the effect of the present disclosure by the reduction rate (%) of the damage value I relative to the usual deep drawing.

[0126] [Formula 1]

[0127]

[0128] C: Material constant

[0129] σ max : Maximum principal stress

[0130] Equivalent plastic strain

[0131] The stamping analysis was conducted for the case where the edge of the blank was pulled out from between the die and the pressing member to complete the forming and the case where the edge of the blank was clamped between the die and the pressing member to complete the forming directly. In addition, the analysis was conducted for the case where the angle θ of the curved portion of the edge of the die when viewed from the stamping direction was 60°, 90°, and 120°.

[0132] exist Fig.18 The analysis results for the case where the blank is pulled out from between the die and the pressing member and the forming is completed are shown in FIG. Fig.19 The results of the analysis are shown in Figure 1. The blank is sandwiched between the die and the pressing member and the forming is completed directly. Fig.18 and Fig.19 As can be seen, when the stamping of the present invention is performed, the damage value I is reduced compared to the usual deep drawing. When the line length of the interval (closest interval) where the interval between the edge of the die on the punch side and the edge of the pressing member on the punch side is the smallest / the line length of the bent portion is greater than 0.5 and less than 2.5, the reduction rate of the damage value I relative to the usual deep drawing is significantly improved.

[0133] Therefore, it can be said that: when observed from the stamping direction, the line length of the portion of the edge of the pressing part on the punch side where the distance from the edge of the die on the punch side is the smallest is preferably greater than 0.5 times and less than 2.5 times the line length of the curved portion of the edge of the die.

[0134] Description of Reference Numerals

[0135] 100, 100A, 100B, stamping device; 10, 10B, punch; 20, 20B, die; 24, edge; 241, bending portion; 30, 30A, 30B, 30C, 30D, 30E, 30F, 30G, 30H, pressing component; 200, blank; 300, 400, stamping product.

Claims

1. A method for manufacturing a stamped product, wherein: The method for manufacturing a press-formed product comprises the steps of clamping a blank with a die and a pressing member and pressing the blank in a pressing direction with a punch. When viewed from the stamping direction, The edge of the die on the punch side includes a curved portion that is convexly curved toward the punch side and extends with a radius of curvature less than 400 mm. The distance between the edge of the pressing member on the punch side and the edge of the die on a perpendicular line in the extending direction of the edge of the die changes along the edge of the die, The spacing is smallest at the bend.

2. The method for manufacturing a press-formed product according to claim 1, wherein: When viewed from the punching direction, the interval increases as it becomes farther away from the bent portion.

3. The method for manufacturing a press-formed product according to claim 1, wherein: When viewed from the stamping direction, The edge of the die is constituted only by the bent portion, The spacing is greatest at the ends of the bend.

4. The method for producing a press-formed product according to any one of claims 1 to 3, wherein: When viewed from the punching direction, the line length of the portion of the edge of the pressing member where the interval is smallest is not less than 0.5 times and not more than 2.5 times the line length of the bent portion.

5. A stamping forming device, wherein: The stamping forming device comprises: Punch; Dies; and Pressing parts, When viewed from the stamping direction, The edge of the die on the punch side includes a curved portion that is convexly curved toward the punch side and extends with a radius of curvature less than 400 mm. The distance between the edge of the pressing member on the punch side and the edge of the die on a perpendicular line in the extending direction of the edge of the die changes along the edge of the die, The spacing is smallest at the bend.

6. The stamping forming device according to claim 5, wherein: When viewed from the punching direction, the interval increases as it becomes farther away from the bent portion.

7. The stamping forming device according to claim 5, wherein: When viewed from the stamping direction, The edge of the die is constituted only by the bent portion, The spacing is greatest at the ends of the bend.

8. The press forming device according to any one of claims 5 to 7, wherein: When viewed from the punching direction, the line length of the portion of the edge of the pressing member where the interval is smallest is not less than 0.5 times and not more than 2.5 times the line length of the bent portion.

Images