Press-formed products and manufacturing methods for press-formed products

Abstract

The present invention provides a press-formed product in which the occurrence of wrinkles is suppressed, and a method for manufacturing a press-formed product. The press-formed product 10A comprises a vertical wall 14 and a flange 18, the vertical wall 14 and the flange 18 being integrally formed via a ridge portion 16. The flange 18 has a return portion 28 in a curved region CA. The return portion 28 protrudes from the end of the flange 18 opposite to the end connected to the vertical wall 14 via the ridge portion 16C, in the same direction as the protruding vertical wall 14. The height length h of the return portion 28 is longer than the plate thickness t of the flange 18.

Description

Technical Field

[0001] The present invention relates to a press-formed product and a manufacturing method for manufacturing the press-formed product.

Background Art

[0002] In flange forming where a blank is press-processed to form a curved edge, in the case of shrink flange forming, wrinkles are likely to occur on the flange. Patent Document 1 discloses a manufacturing method for a press-formed product in which a blank is press-processed using a die, a punch, and a blank holder (hereinafter also simply referred to as a "holder") in order to suppress the occurrence of wrinkles on the flange. The blank holder is a component that sandwiches the blank between itself and the die and applies a force to hold down the blank when performing drawing forming with a mold.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In flange forming, it is required to further suppress the occurrence of wrinkles. Such a requirement is not limited to high-tensile steel sheets and the like described in Patent Document 1 above.

[0005] An object of the present invention is to provide a press-formed product in which the occurrence of wrinkles is suppressed and a manufacturing method for the press-formed product.

Means for Solving the Problems

[0006] As one of the means for solving the above problems, the present application discloses the following plurality of aspects.

[0007] [Aspect 1] A press-formed product comprising a vertical wall and a flange, wherein the vertical wall and the flange are integrally formed via a ridge, The flange has a return portion in the curved region that becomes a contracted flange, The aforementioned return portion protrudes from the end of the flange opposite to the end of the flange connected to the vertical wall via the ridge portion, in the same direction as the vertical wall protruding in the thickness direction of the flange. A press-formed product in which the length h in the thickness direction of the return portion is longer than the plate thickness t of the flange. [Aspect 2] The press-formed product according to embodiment 1, wherein the surface of the return portion facing the vertical wall is linear when viewed from a cross section perpendicular to the extending direction of the ridge portion. [Aspect 3] The press-formed product according to embodiment 2, wherein the ridge portion has a curved ridge portion that, when viewed from the thickness direction, protrudes from the vertical wall toward the flange. [Aspect 4] The press-formed product according to embodiment 3, wherein the angle between the flange and the return portion, as viewed from a cross section perpendicular to the direction of extension of the curved ridge portion, is 90 degrees or more and 150 degrees or less. [Aspect 5] The press-formed product according to embodiment 2, wherein the ridge portion has a curved ridge portion that, when viewed from a direction perpendicular to the extending direction and the thickness direction of the ridge portion, is curved in a direction that protrudes from the flange toward the vertical wall. [Aspect 6] The press-formed product according to embodiment 5, wherein the angle between the flange and the return portion, as viewed from a cross section perpendicular to the direction of extension of the curved ridge portion, is 90 degrees or more and 120 degrees or less. [Aspect 7] The press-formed product according to any one of embodiments 1 to 6, wherein the press-formed product is made of a metal plate and the Vickers hardness of the metal plate is 300 HV or more. [Aspect 8] A method for manufacturing a press-formed article according to any one of embodiments 1 to 7, comprising the step of forming the ridge portion by pad bending, stamping, or cam bending. [Aspect 9] A method for manufacturing a press-formed product according to embodiment 8, comprising a pressing step for simultaneously forming the vertical wall, the flange, and the return portion. [Aspect 10] The press-formed product according to embodiment 1 or 2, wherein the ridge portion has a curved ridge portion when viewed from the thickness direction of the flange or when viewed from the thickness direction of the vertical wall. [Effects of the Invention]

[0008] According to the present invention, a press-molded product in which the occurrence of wrinkles is suppressed can be obtained. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partial perspective view showing a press-formed product according to the first embodiment. [Figure 2] This is a cross-sectional view of a press-formed product according to the first embodiment, taken along line II-II in Figure 1. [Figure 3] This is a vertical cross-sectional view illustrating the manufacturing method of a press-formed product according to the first embodiment, showing the blank set in the mold. [Figure 4] This is a longitudinal cross-sectional view illustrating the manufacturing method of a press-formed product according to the first embodiment, showing the state after press forming is completed. [Figure 5] This is a partial perspective view showing a press-formed product according to the second embodiment. [Figure 6] This is a partial plan view showing a press-formed product according to the second embodiment. [Figure 7] This is a partial side view showing a press-formed product according to the second embodiment. [Figure 8] This is a cross-sectional view of a press-formed product according to the second embodiment, taken along the line VI-VI in Figure 5. [Figure 9] This is a longitudinal cross-sectional view illustrating the manufacturing method of a press-formed product according to the second embodiment, showing the blank set in the mold. [Figure 10]It is a longitudinal sectional view showing step by step the manufacturing method of the press-formed product according to the second embodiment, and is a view showing the state where the press forming is completed. [Figure 11A] In another manufacturing method of the press-formed product according to the first embodiment, it is a longitudinal sectional view showing the state where a blank is set in a mold. [Figure 11B] In another manufacturing method of the press-formed product according to the first embodiment, it is a longitudinal sectional view showing the state where the blank is sandwiched by a pad. [Figure 11C] In another manufacturing method of the press-formed product according to the first embodiment, it is a longitudinal sectional view showing the state where the blank is formed by a die. [Figure 12] It is a schematic view of a flange for explaining the strain difference between the front and back of the flange. [Figure 13] It is a graph showing the result of simulation model 1. [Figure 14] It is a graph showing the result of simulation model 2.

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, in an arbitrary cross section where the angle formed by the vertical wall and the flange having a shrink flange shape in the extending direction of the vertical wall of the press-formed product (also referred to as the "length direction") is minimized, the width direction and the height direction are defined. The vertical wall only needs to be in an intersecting relationship with the flange and is not limited to the posture and orientation during use. Intersection means that the vertical wall and the flange intersect through a ridge line portion. The "shrink flange" is a flange formed by raising or bending the edge of a plate material, and refers to a phenomenon in which compressive strain mainly occurs in the circumferential direction of the flange (the extending direction of the flange). The above cross section refers to a cross section orthogonal to the extending direction of the ridge line portion. When the ridge line portion is curved, the above cross section refers to a cross section orthogonal to the tangent line of the ridge line portion. The width direction is defined as the direction in which the flange extends in the above cross-section. That is, in the said cross-section, the width direction is defined as the direction connecting the flange end and the radius end on the flange side of the ridge line connecting the flange and the vertical wall. The flange end is the outer edge opposite to the side connected to the vertical wall of the flange. The height direction is defined as the thickness direction of the flange in the cross-section. The side of the tabletop that faces the center in the width direction is called the inner side in the width direction, and the side that moves away from the center in the width direction is called the outer side in the width direction. In this specification, "same length" does not mean exactly the same length, but includes a difference of ±10% from the length in question. Unless otherwise specified, angles shall be considered inferior angles.

[0011] 1. First Embodiment [Press-formed product] The press-formed product 10A shown in Figure 1 is made of a metal sheet and has a hat-shaped cross-section. The press-formed product 10A integrally comprises a top plate 12, a pair of vertical walls 14 provided at opposite ends in the width direction of the top plate 12, and flanges 18 connected to the lower ends of the pair of vertical walls 14 via ridge portions 16. The outer edge of the flange 18 opposite to the side connected to the vertical wall 14 is called the flange end.

[0012] The press-formed product 10A has an L-shaped outer shape when viewed from the height direction, i.e., in a plan view. The top plate 12 also has an L-shaped outer shape in a plan view. In the press-formed product 10A, the L-shaped curved portion is specifically called the curved region CA, and the straight portion other than the curved region CA is called the straight region LA. The curved region CA refers to the range from one end of R in the extending direction of the press-formed product 10A to the other end of R in the extending direction. The bending radius R in the curved region CA is 10 mm to 500 mm. The straight region LA refers to the range where the extending direction of the press-formed product is straight, up to just before the end of R in the curved region CA.

[0013] The vertical wall 14 has a first vertical wall 20 located on the outside of the bend in the curved region CA, and a second vertical wall 22 located on the inside of the bend in the curved region CA. The first vertical wall 20 has, in a plan view, a convex vertical wall 20C that is curved in a direction that is convex outward in the width direction, and a straight first vertical wall 20L that is straight and not curved in the width direction. The second vertical wall 22 has, in a plan view, a concave vertical wall 22D that is curved in a direction that is concave outward in the width direction, and a straight second vertical wall 22L that is straight and not curved in the width direction.

[0014] The flange 18 has a first flange 24 positioned on the outside of the bend in the curved region CA, and a second flange 26 positioned on the inside of the bend in the curved region CA. In a plan view, the first flange 24 has a convex flange 24C that is curved in a direction that is convex outward in the width direction, and a straight flange 24L that is straight and not curved in the width direction. In a plan view, the second flange 26 has a concave flange 26D that is curved in a direction that is concave outward in the width direction, and a straight flange 26L that is straight and not curved in the width direction.

[0015] The ridge section 16 has a curved ridge section 16C that connects the first vertical wall 20 and the second vertical wall 22 to the flange 18 in the curved region CA, and a straight ridge section 16L that connects the first vertical wall 20 and the second vertical wall 22 to the flange 18 outside the curved region CA.

[0016] The curved ridge section 16C has a convex ridge section 16CC that connects the convex vertical wall 20C and the convex flange 24C, and a concave ridge section 16CL that connects the concave vertical wall 22D and the concave flange 26D. In a plan view, the convex ridge section 16CC is curved in a direction that is convex from the convex vertical wall 20C toward the convex flange 24C. In a plan view, the concave ridge section 16CL is curved in a direction that is concave when viewed from the concave flange 26D.

[0017] The press-formed product 10A has one curved region CA and straight regions LA on both sides of the curved region CA. Specifically, in the curved region CA, a concave flange 26D, a concave ridge section 16CL, a concave vertical wall 22D, a top plate 12, a convex vertical wall 20C, a convex ridge section 16CC, and a convex flange 24C are arranged in order from the inside to the outside of the bend. The convex flange 24C has a contracted flange shape. In the straight regions LA, a straight flange 26L, a straight ridge section 16L, a straight second vertical wall 22L, a top plate 12, a straight first vertical wall 20L, a straight ridge section 16L, and a straight flange 24L are arranged in order from the second vertical wall 22 toward the first vertical wall 20.

[0018] The press-formed product 10A according to the first embodiment further integrally includes a return portion 28. The return portion 28 is provided on the first flange 24 so as to face the first vertical wall 20. Here, "integrated" means that the return portion 28 and the first flange 24 are continuous, but does not limit the range of the return portion 28 with respect to the range in the extending direction of the first flange 24. The return portion 28 is provided at the end of the first flange 24 opposite to the end on which the first vertical wall 20 is connected, that is, at the flange end of the first flange 24 on the outside of the bend. The return portion 28 protrudes from the first flange 24 in the same direction as the first vertical wall 20 protruding. That is, the return portion 28 protrudes from the flange end opposite to the end of the first flange 24 connected to the first vertical wall 20 via the curved ridge portion 16C in the same direction as the first vertical wall 20 protruding in the height direction. The return portion 28 may be provided along the first flange 24 over the entire length of the press-formed product 10A.

[0019] As shown in Figure 2, a longitudinal cross-sectional view of the curved region CA of the press-formed product 10A, the angle θ between the return portion 28 and the first flange 24, viewed from a cross section perpendicular to the extension direction of the curved ridge portion 16C in the curved region CA, may be 90 degrees or more and 150 degrees or less, or for example, greater than 90 degrees, 92 degrees or more, 95 degrees or more, less than 142.5 degrees, 140 degrees or less, or 135 degrees or less. The cross section perpendicular to the extension direction of the curved ridge portion refers to the cross section perpendicular to the tangent to the curved ridge portion 16C.

[0020] The surface of the return portion 28 facing the vertical wall 14 is preferably straight when viewed from a cross section perpendicular to the extending direction of the curved ridge portion 16C. The surface of the return portion 28 facing the vertical wall 14 is preferably flat when viewed from a cross section perpendicular to the extending direction of the curved ridge portion 16C. Here, a flat surface means that the return portion 28 is not curved in the thickness direction in the range from the R end between the return portion 28 and the flange end to the upper end of the return portion 28. In the following description, "flat surface" includes a surface having irregularities that constitute the surface roughness of the member surface.

[0021] The length h in the height direction of the return portion 28 is longer than the plate thickness t of the first flange 24. The length h is the height from the bottom surface 24B to the upper end of the return portion 28, assuming that the surface of the first flange 24 on the first vertical wall 20 side is the top surface 24F and the surface opposite to the top surface 24F is the bottom surface 24B. It is preferable that the length h is shorter than the length H in the height direction of the press-formed product 10A. The length H is the height from the bottom surface 24B of the first flange 24 to the surface 12F of the top plate 12. If the height from the bottom surface 24B of the first flange 24 to the surface 12F of the top plate 12 is not constant, the length H is the maximum height from the bottom surface 24B of the first flange 24 to the surface 12F of the top plate 12. The length h of the return portion 28 may be, for example, 2t or more, 3t or more, or 4t or more relative to the plate thickness t, and may be 0.9H or less, 0.8H or less, or 0.7H or less relative to the length H.

[0022] In the first embodiment, the press-formed product 10A has a top plate 12 and a flange 18 that are substantially parallel to each other, and the vertical wall 14 extends in a direction intersecting the top plate 12 and the flange 18. In the first embodiment, the height H of the press-formed product 10A is the same throughout its entire length. The press-formed product 10A preferably has a Vickers hardness of 300 HV or more.

[0023] [Method for manufacturing press-formed products] (Mold) First, the mold used in the manufacturing method of the press-formed product 10A according to the first embodiment will be described. The description will primarily focus on the case where the portion corresponding to the curved region CA of the press-formed product 10A, which is a characteristic feature of the first embodiment, is formed. Note that the width direction and height direction in the following description are the same as those of the press-formed product 10A.

[0024] Figure 3 is a longitudinal cross-sectional view of the press die and blank when forming the curved region CA of the press-formed product 10A. That is, in Figure 3, the left side is the outside of the bend in the curved region CA, and the right side is the inside of the bend in the curved region CA. As shown in Figure 3, the die 30A comprises an upper die 32 and a lower punch 34. The die 30A is installed in a press machine, although it is not shown.

[0025] The die 32 has a first molding surface 32S on the side facing the punch 34 with the blank 36 in between. The first molding surface 32S is in contact with the first surface 36F of the blank 36. The first molding surface 32S is provided with a first recess 38 recessed in the center in the width direction relative to the blank 36, and first protrusions 40 provided on both sides of the first recess 38 in the width direction and projecting toward the blank 36.

[0026] The first molding surface 32S has a first concave surface 32SD, a first convex surface 32SC, a first inclined surface 32ST, and a first outer wall surface 32SW. The first concave surface 32SD is formed in the center in the width direction by a first recess 38 and is positioned recessed relative to the blank 36. The first concave surface 32SD is flat in the height direction and has a size that allows the top plate 12 to be molded.

[0027] The first convex surface 32SC is formed on both sides in the width direction of the first concave surface 32SD by the first protrusion 40 and is positioned to protrude toward the blank 36. The first convex surface 32SC has a first outer surface 32SS and a first inner surface 32SU.

[0028] The first outer surface 32SS is located on the outside of the bend and has a size that allows for the formation of a convex flange 24C. The first outer surface 32SS is flat in the height direction and has an outer shape that curves in a direction that is convex outward in the width direction. The first inner surface 32SU is located on the inside of the bend and has a size that allows for the formation of a concave flange 26D. The first inner surface 32SU is flat in the height direction and has an outer shape that curves in a direction that is concave inward in the width direction.

[0029] The first inclined surface 32ST connects the first concave surface 32SD and the first convex surface 32SC. The first inclined surface 32ST is inclined outward in the width direction from the first concave surface 32SD toward the blank 36. The first inclined surface 32ST has a first concave wall surface 32STD and a first convex wall surface 32STC. The first concave wall surface 32STD is located on the outside of the bend in Figure 3, curves in a direction that is convex toward the outside in the width direction, and has a size that allows for the formation of the convex vertical wall 20C. The first convex wall surface 32STC is located on the inside of the bend, curves in a direction that is convex toward the inside in the width direction, and has a size that allows for the formation of the concave vertical wall 22D.

[0030] The first outer wall surface 32SW is formed on the widthwise outer side of the first outer surface 32SS and has the shape of an inverted truncated cone.

[0031] The sections between the first concave surface 32SD and the first inclined surface 32ST, between the first inclined surface 32ST and the first convex surface 32SC, and between the first convex surface 32SC and the first outer wall surface 32SW may have a cross-sectional radius (R). The section between the first concave wall surface 32STD and the first outer surface 32SS will be called the first outer ridge 32RC. The section between the first convex wall surface 32STC and the first inner surface 32SU will be called the first inner ridge 32RD.

[0032] The punch 34 has a second molding surface 34S on the side facing the die 32 with the blank 36 in between. The second molding surface 34S is in contact with the second surface 36B of the blank 36. The second molding surface 34S is provided with a second convex portion 42 projecting toward the blank 36 from the center in the width direction, second recesses 44 provided on both sides of the second convex portion 42 in the width direction and recessed relative to the blank 36, and a second outer convex portion 46 projecting upward only on the left side in Figure 3.

[0033] The second molded surface 34S has a second convex surface 34SC, a second concave surface 34SD, a second inclined surface 34ST, a second outer convex surface 34SSC, and a second outer wall surface 34SW.

[0034] The second convex surface 34SC is formed in the center in the width direction by the second protrusion 42 and is positioned to protrude toward the blank 36. The second convex surface 34SC is flat in the height direction and has a size that allows the top plate 12 to be molded.

[0035] The second concave surface 34SD is formed on both sides in the width direction of the second convex surface 34SC by the second recess 44 and is positioned recessed relative to the blank 36. The second concave surface 34SD has a second outer surface 34SS and a second inner surface 34SU. The second outer surface 34SS is located on the outside of the bend and is sized to form the convex flange 24C. The second outer surface 34SS is flat in the height direction and has an outer shape that curves in a direction that is convex toward the outside in the width direction. The second inner surface 34SU is located on the inside of the bend and is sized to form the concave flange 26D. The second inner surface 34SU is flat in the height direction and has an outer shape that curves in a direction that is concave toward the inside in the width direction.

[0036] The second inclined surface 34ST connects the second convex surface 34SC and the second concave surface 34SD. The second inclined surface 34ST is inclined outward in the width direction from the blank 36 toward the second concave surface 34SD. The second inclined surface 34ST has a second convex wall surface 34STC and a second concave wall surface 34STD. The second convex wall surface 34STC is located on the outside of the bend, curves in a direction that is convex outward in the width direction, and has a size that allows for the formation of a convex vertical wall 20C. The second concave wall surface 34STD is located on the inside of the bend, curves in a direction that is concave inward in the width direction, and has a size that allows for the formation of a concave vertical wall 22D.

[0037] The second outer convex surface 34SSC is formed on the widthwise outer side of the second outer surface 34SS and is positioned to protrude toward the blank 36. The second outer convex surface 34SSC is flat in the height direction.

[0038] The second outer wall surface 34SW connects the second outer surface 34SS and the second outer convex surface 34SSC. The second outer wall surface 34SW has the shape of the inner surface of a funnel.

[0039] The sections between the second convex surface 34SC and the second inclined surface 34ST, between the second inclined surface 34ST and the second concave surface 34SD, and between the second outer surface 34SS and the second outer wall surface 34SW may have a cross-sectional radius (R). The section between the second convex wall surface 23STC and the second outer surface 34SS will be called the second outer ridge 34RC. The section between the second concave wall surface 34STU and the second inner surface 34SU will be called the second inner ridge 34RD.

[0040] The first concave surface 32SD of the die 32 and the second convex surface 34SC of the punch 34 form the top plate 12 of the press-formed product 10A. The first concave wall surface 32STD of the die 32 and the second convex wall surface 34STC of the punch 34 form the convex vertical wall 20C of the press-formed product 10A. The first convex wall surface 32STC of the die 32 and the second concave wall surface 34STD of the punch 34 form the concave vertical wall 22D of the press-formed product 10A. The first outer surface 32SS of the die 32 and the second outer surface 34SS of the punch 34 form the convex flange 24C of the press-formed product 10A. The first inner surface 32SU of the die 32 and the second inner surface 34SU of the punch 34 form the concave flange 26D of the press-formed product 10A. The first outer wall surface 32SW of the die 32 and the second outer wall surface 34SW of the punch 34 form the return portion 28 of the press-formed product 10A. The first outer ridge 32RC of the die 32 and the second outer ridge 34RC of the punch 34 form the convex ridge portion 16CC of the press-formed product 10A. The first inner ridge 32RD of the die 32 and the second inner ridge 34RD of the punch 34 form the concave ridge portion 16CL of the press-formed product 10A.

[0041] The blank 36 is a metal plate, for example, a steel plate with a thickness of 0.1 mm to 5 mm. Preferably, the blank 36 has a Vickers hardness of 300 HV or more. The blank 36 is formed such that its outer peripheral edge 36E protrudes outward in the width direction from the first protrusion 40 of the die 32.

[0042] (Manufacturing method) Next, the process of forming the press-formed product 10A using the mold 30A described above will be explained. First, a plate-shaped blank 36, which has been pre-formed to have a predetermined outer circumference shape, is set between the die 32 and the punch 34 (Figure 3). At this time, the blank 36 is positioned in the mold 30A by positioning pins (not shown) or by guides (not shown) that support the periphery of the blank 36.

[0043] Next, the die 32 is moved downward. This causes the blank 36 to be sandwiched between the first protrusion 40 of the die 32 and the second protrusion 42 and second outer protrusion 46 of the punch 34. As the die 32 is lowered further, the second protrusion 42 of the punch 34 enters the first recess 38 of the die 32, and the first protrusion 40 of the die 32 enters the second recess 44 of the punch 34, thereby gradually forming the top plate 12, vertical wall 14, and flange 18.

[0044] In this process, the outer peripheral edge 36E of the blank 36, which protrudes outward from the first protrusion 40 of the die 32, begins to deform in the opposite direction to the pressing direction by the second outer protrusion 46 as the die 32 moves downward. Furthermore, as the die 32 is lowered, the outer peripheral edge 36E of the blank 36 is sandwiched between the first outer wall surface 32SW of the first protrusion 40 and the second outer wall surface 34SW of the punch 34, and is bent to the same side as the vertical wall 14, gradually forming a return portion 28. In this state, as shown in Figure 4, the die 32 is lowered until it reaches the bottom dead center, completing the molding of the blank 36. As a result, a press-formed product 10A having a curved ridge portion 16C that is curved when viewed from the height direction can be obtained.

[0045] As described above, the manufacturing method according to the first embodiment simultaneously forms the vertical wall 14, the flange 18, and the return portion 28. Here, "simultaneously" means that the formation is done in a single pressing step using a die 32 which integrally includes a first concave surface 32SD, a first convex surface 32SC, a first inclined surface 32ST, and a first outer wall surface 32SW.

[0046] [Mechanism of Action and Effects] The operation and effects of the press-formed product 10A and the method for manufacturing the press-formed product 10A according to the first embodiment described above will be explained.

[0047] As described in the "Manufacturing Method" above, the second protrusion 42 of the punch 34 enters the first recess 38 of the die 32, and the first protrusion 40 of the die 32 enters the second recess 44 of the punch 34. The first concave wall surface 32STD of the die 32 and the second convex wall surface 34STC of the punch 34 form a convex vertical wall 20C on the outside of the bend, so the blank material 36 flows between the first concave wall surface 32STD and the second convex wall surface 34STC. As a result, a compressive force is generated in the in-plane direction in the portion of the blank 36 corresponding to the convex flange 24C sandwiched between the first outer surface 32SS of the die 32 and the second outer surface 34SS of the punch 34.

[0048] The outer peripheral edge 36E of the blank 36 is sandwiched between the first outer wall surface 32SW of the first protrusion 40 and the second outer wall surface 34SW of the punch 34, and is bent to the same side as the vertical wall 14, thereby forming a return portion 28. As a result, compared to the absence of a return portion, the bending rigidity of the blank 36 with respect to the width direction of the portion corresponding to the protrusion flange 24C is increased, and the occurrence of wrinkles in that portion is suppressed.

[0049] In the first embodiment, while forming the vertical wall 14, the outer peripheral edge 36E of the blank 36 that protrudes outward from the first protrusion 40 of the die 32 is sandwiched between the first outer wall surface 32SW of the first protrusion 40 and the second outer wall surface 34SW of the punch 34 and bent to the same side as the vertical wall 14. In other words, the manufacturing method according to the first embodiment simultaneously forms the vertical wall 14, the flange 18, and the return portion 28. The formation of the return portion 28 in this manner increases the rigidity of the portion of the blank 36 corresponding to the protrusion flange 24C. By increasing the bending rigidity of the portion corresponding to the protrusion flange 24C, where compressive force is generated in the in-plane direction, along the width direction axis, the occurrence of wrinkles in the protrusion flange 24C can be suppressed.

[0050] As described above, according to the first embodiment, wrinkle formation can be suppressed without pressing down on the outer edge of the blank with a holder. Therefore, the press-formed product 10A and the method for manufacturing the press-formed product 10A according to this embodiment do not require a holder, thus simplifying the structure of the mold 30A and reducing manufacturing costs.

[0051] By having a height-direction length h of the return portion 28 that is greater than the plate thickness t of the first flange 24, the occurrence of wrinkles in the convex flange 24C can be more reliably suppressed. By having an angle θ between the return portion 28 and the first flange 24 of 90 degrees or more, as viewed from a cross section perpendicular to the extension direction of the curved ridge portion 16C, the stress generated between the return portion 28 and the first flange 24 can be suppressed, thereby preventing cracks from occurring in the first flange 24. By having an angle θ between the return portion 28 and the first flange 24 of 150 degrees or less, as viewed from a cross section perpendicular to the extension direction of the curved ridge portion 16C, the occurrence of wrinkles can be more reliably suppressed.

[0052] 2. Second Embodiment [Press-formed product] The press-formed product 10B shown in Figures 5, 6, and 7 is a long member made of a metal sheet and having a hat-shaped cross-section. The press-formed product 10B integrally comprises a top plate 48, a pair of vertical walls 50 provided at opposite ends of the top plate 48 in the width direction, and flanges 54 connected to the lower ends of the pair of vertical walls 50 via ridge portions 52. Since the press-formed product 10B is symmetrical with respect to the center in the width direction, one side in the width direction will be described, and the description of the other side will be omitted as appropriate.

[0053] The press-formed product 10B has an I-shaped outline in plan view (Figure 6). The top plate 48 has a rectangular outline in plan view. The press-formed product 10B has a mountain-shaped outline when viewed from the width direction, i.e., in side view (Figure 7). In the press-formed product 10B, the mountain-shaped curved portion is specifically called the curved region CA, and the straight portion other than the curved region CA is called the straight region LA. The curved region CA refers to the range from one R-end in the extending direction of the press-formed product 10B to the other R-end in the extending direction. The bending radius R in the curved region CA is 10 mm to 1000 mm. The area from the center in the height direction of the curved region CA towards the top plate 48 is called the outside of the bend, and the area from the center in the height direction towards the flange 54 is called the inside of the bend. The straight region LA refers to the range where the extending direction of the press-formed product is straight and extends up to just before the R-end in the curved region CA.

[0054] The top plate 48 has a convex top plate 48C in the curved region CA and a straight top plate 48L in the straight region LA. The convex top plate 48C is curved in the height direction so as to be convex from the flange 54 toward the top plate 48. The vertical wall 50 has a convex vertical wall 50C in the curved region CA and a straight vertical wall 50L in the straight region LA. The convex vertical wall 50C is flat and not curved in the width direction, and is curved in the height direction so as to be convex toward the top plate 48.

[0055] The flange 54 has a convex flange 54C in the curved region CA and a linear flange 54L in the linear region LA. The convex flange 54C is curved in a direction that is convex toward the top plate 48 in the height direction.

[0056] The ridge portion 52 has a convex ridge portion 52C that connects the convex vertical wall 50C and the convex flange 54C in the curved region CA, and a linear ridge portion 52L that connects the linear vertical wall 50L and the linear flange 54L. In a side view, the convex ridge portion 52C is curved in a direction that is convex from the convex flange 54C toward the convex vertical wall 50C.

[0057] The press-formed product 10B has one curved region CA and linear regions LA on each side of the curved region CA. That is, it is symmetrical with respect to the center in the width direction of the curved region CA, and a convex top plate 48C, a convex vertical wall 50C, a convex ridge portion 52C, and a convex flange 54C are arranged in order from the center to both sides in the width direction. The convex flange 54C has a contracted flange shape. In the linear region LA, a linear top plate 48L, a linear vertical wall 50L, a linear ridge portion 52L, and a linear flange 54L are arranged in order from the center to both sides in the width direction.

[0058] The press-formed product 10B according to the second embodiment further includes a return portion 56. The return portion 56 is provided at the end of the flange 54 that is connected to the vertical wall 50 and the end opposite to it. The return portion 56 protrudes from the flange 54 in the same direction as the vertical wall 50 protruding. That is, the return portion 56 protrudes from the flange end opposite to the end of the flange 54 that is connected to the convex vertical wall 50C via the convex ridge portion 52C, in the same direction as the convex vertical wall 50C protruding in the height direction. The return portion 56 may be provided along the flange 54 over the entire length of the press-formed product 10B.

[0059] As shown in Figure 8, a longitudinal cross-sectional view of the curved region CA of the press-formed product 10B, the angle θ between the return portion 56 and the convex flange 54C, viewed from a cross section perpendicular to the extension direction of the convex ridge portion 52C as the curved ridge portion in the curved region CA, may be 90 degrees or more and 120 degrees or less, or for example, greater than 90 degrees, 92 degrees or more, 95 degrees or more, less than 120 degrees, 115 degrees or less, or 110 degrees or less. The cross section perpendicular to the extension direction of the convex ridge portion refers to the cross section perpendicular to the tangent to the convex ridge portion 52C.

[0060] The surface of the return portion 56 facing the vertical wall 50 is preferably straight when viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C. The surface of the return portion 56 facing the vertical wall 50 is preferably flat when viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C. That is, the surface of the return portion 56 facing the convex vertical wall 50C is preferably flat when viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C. Here, a flat surface means that, in the range from the R-end between the return portion 56 and the flange end to the upper end of the return portion 56, it is not curved when viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C. This also includes the case where the surface has irregularities that constitute the surface roughness of the member surface.

[0061] The length h in the height direction of the return portion 56 is longer than the plate thickness t of the flange 54. The length h is the height from the bottom surface 54B to the upper end of the return portion 56, assuming that the surface of the flange 54 on the vertical wall 50 side is the top surface 54F and the surface opposite to the top surface 54F is the bottom surface 54B. Preferably, the length h is shorter than the length H in the height direction of the press-formed product 10B. The length H is the height from the bottom surface 54B of the flange 54 to the surface 48F of the top plate 48 on the vertical end surface perpendicular to the surface direction of the top plate 48. The length h of the return portion 56 may be, for example, 2t or more, 3t or more, or 4t or more relative to the plate thickness t, and may be 0.9H or less, 0.8H or less, or 0.7H or less relative to the length H.

[0062] In the press-formed product 10B according to the second embodiment, the top plate 48 and the flange 54 are substantially parallel to each other, and the vertical wall 50 extends in a direction intersecting the top plate 48 and the flange 54. Also, in the second embodiment, the height length H of the press-formed product 10B is the same throughout the entire length of the press-formed product 10B. Preferably, the press-formed product 10B has a Vickers hardness of 300 HV or more.

[0063] [Method for manufacturing press-formed products] (Mold) The mold 30B used in the manufacturing method of the press-formed product 10B according to the second embodiment will be described. The description will mainly focus on the case where the portion corresponding to the curved region CA of the press-formed product 10B, which is a characteristic part of the second embodiment, is formed. The mold 30B according to the second embodiment is symmetrical with respect to the center in the width direction, just like the press-formed product 10B, so the description will mainly focus on one side in the width direction, and the other side will be omitted.

[0064] As shown in Figure 9, the mold 30B comprises an upper die 58 and a lower punch 60. In Figure 9, the upper side is the outer side of the bend in the curved region CA, and the lower side is the inner side of the bend in the curved region CA.

[0065] The die 58 has a first molding surface 58S on the side facing the punch 60 with the blank 62 in between. The first molding surface 58S is in contact with the first surface 62F of the blank 62. The first molding surface 58S is provided with a first recess 64 recessed in the center in the width direction relative to the blank 62, and first protrusions 66 provided on both sides of the first recess 64 in the width direction and protruding relative to the blank 62.

[0066] The first molding surface 58S has a first concave surface 58SD, a first convex surface 58SC, a first inclined surface 58ST, and a first outer wall surface 58SW. The first concave surface 58SD is formed in the center in the width direction by a first recess 64 and is positioned recessed relative to the blank 62. The first concave surface 58SD is curved in a direction that is concave toward the blank 62 in the height direction when viewed from the width direction and has a size that allows the top plate 48 to be molded.

[0067] The first convex surface 58SC is formed on both sides in the width direction of the first concave surface 58SD by the first convex portion 66 and is positioned to protrude toward the blank 62. When viewed from the width direction, the first convex surface 58SC is curved in a direction that is concave toward the blank 62 in the height direction and has a size that allows for the formation of the convex flange 54C.

[0068] The first inclined surface 58ST connects the first concave surface 58SD and the first convex surface 58SC. The first inclined surface 58ST is inclined outward in the width direction from the first concave surface 58SD toward the first convex surface 58SC. The first inclined surface 58ST is a flat surface that is not curved perpendicular to the first inclined surface 58ST. The first inclined surface 58ST has an outer shape that is curved in a direction that is concave toward the blank 62 in the height direction when viewed from the width direction, and has a size that allows for the formation of the convex vertical wall 50C.

[0069] The first outer wall surface 58SW is formed on the widthwise outer side of the first convex surface 58SC and has the shape of an inverted truncated square pyramid. The spaces between the first concave surface 58SD and the first inclined surface 58ST, between the first inclined surface 58ST and the first convex surface 58SC, and between the first convex surface 58SC and the first outer wall surface 58SW may have a cross-sectional radius (R). The space between the first inclined surface 58ST and the first convex surface 58SC will be called the first ridge portion 58R.

[0070] The punch 60 has a second molding surface 60S on the side facing the die 58 with the blank 62 in between. The second molding surface 60S is provided with a second convex portion 68 projecting toward the blank 62 from the center in the width direction, second recesses 70 provided on both sides of the second convex portion 68 in the width direction and recessed relative to the blank 62, and second outer convex portions 72 projecting toward the blank 62 on both sides in the width direction.

[0071] The second molding surface 60S has a second convex surface 60SC, a second concave surface 60SD, a second inclined surface 60ST, a second outer convex surface 60SSC, and a second outer wall surface 60SW.

[0072] The second convex surface 60SC is formed in the center in the width direction by the second protrusion 68 and is positioned to protrude toward the blank 62. The second convex surface 60SC is curved in a direction that is convex toward the blank 62 in the height direction when viewed from the width direction and has a size that allows for the molding of the convex top plate 48C.

[0073] The second concave surface 60SD is formed on both sides in the width direction of the second convex surface 60SC by the second recess 70 and is positioned recessed relative to the blank 62. The second concave surface 60SD is curved in a direction that is convex toward the blank 62 in the height direction when viewed from the width direction and has a size that allows for the formation of the convex flange 54C.

[0074] The second inclined surface 60ST connects the second convex surface 60SC and the second concave surface 60SD. The second inclined surface 60ST is inclined outward in the width direction from the second convex surface 60SC toward the second concave surface 60SD. The second inclined surface 60ST is a flat surface that is not curved perpendicular to the second inclined surface 60ST. The second inclined surface 60ST has an outer shape that is curved in a direction that is convex toward the blank 62 in the height direction when viewed from the width direction, and has a size that allows for the formation of the convex vertical wall 50C.

[0075] The second outer convex surface 60SSC is formed on the widthwise outer side of the second concave surface 60SD and is positioned to protrude toward the blank 62. The second outer convex surface 60SSC is curved in a direction that is convex toward the blank 62 in the height direction when viewed from the width direction.

[0076] The second outer wall surface 60SW connects the second concave surface 60SD and the second outer convex surface 60SSC. The second outer wall surface 60SW has a lateral shape resembling an inverted truncated square pyramid.

[0077] The sections between the second convex surface 60SC and the second inclined surface 60ST, between the second inclined surface 60ST and the second concave surface 60SD, between the second concave surface 60SD and the second outer wall surface 60SW, and between the second outer wall surface 60SW and the second outer convex surface 60SSC may have a cross-sectional radius (R). The section between the second inclined surface 60ST and the second concave surface 60SD will be referred to as the second ridge portion 60R.

[0078] The first concave surface 58SD of the die 58 and the second convex surface 60SC of the punch 60 form the convex top plate 48C of the press-formed product 10B. The first inclined surface 58ST of the die 58 and the second inclined surface 60ST of the punch 60 form the convex vertical wall 50C of the press-formed product 10B. The first convex surface 58SC of the die 58 and the second concave surface 60SD of the punch 60 form the convex flange 54C of the press-formed product 10B. The first outer wall surface 58SW of the die 58 and the second outer wall surface 60SW of the punch 60 form the return portion 56 of the press-formed product 10B. The first ridge portion 58R of the die 58 and the second ridge portion 60R of the punch 60 form the convex ridge line portion 52C of the press-formed product 10B.

[0079] (Manufacturing method) Next, the process of forming the press-formed product 10B using the mold 30B described above will be explained. A plate-shaped blank 62, which has been pre-formed to have a predetermined outer circumference shape, is set between the die 58 and the punch 60, and then the die 58 is moved downward. As the die 58 is lowered further from the state in which the blank 62 is sandwiched between the die 58 and the punch 60, the second protrusion 68 of the punch 60 enters the first recess 64 of the die 58, and the first protrusion 66 of the die 58 enters the second recess 70 of the punch 60, thereby gradually forming the top plate 48, the vertical wall 50, and the flange 54.

[0080] In this process, the outer peripheral edges 62E of the blank 62, which protrude to the left and right from the first protrusion 66 of the die 58, begin to deform in the opposite direction to the pressing direction by the second outer protrusion 72 as the die 58 moves downward. Furthermore, as the die 58 is lowered, the outer peripheral edges 62E of the blank 62 are sandwiched between the first outer wall surface 58SW of the first protrusion 66 and the second outer wall surface 60SW of the punch 60, and are bent to the same side as the vertical wall 50, gradually forming a return portion 56. In this state, as shown in Figure 10, the die 58 is lowered until it reaches the bottom dead center, completing the molding of the blank 62. As a result, a press-formed product 10B having a convex ridge portion 52C as a curved ridge portion when viewed from the width direction can be obtained.

[0081] The manufacturing method according to the second embodiment simultaneously forms the vertical wall 50, the flange 54, and the return portion 56. Here, "simultaneously" means forming them in a single press step using a die 58 that integrally includes a first concave surface 58SD, a first convex surface 58SC, a first inclined surface 58ST, and a first outer wall surface 58SW.

[0082] [Mechanism of Action and Effects] The operation and effects of the press-formed product 10B and the method for manufacturing the press-formed product 10B according to the second embodiment described above will be explained.

[0083] As described in the "Manufacturing Method" above, the second protrusion 68 of the punch 60 enters the first recess 64 of the die 58, and the first protrusion 66 of the die 58 enters the second recess 70 of the punch 60. Furthermore, the first inclined surface 58ST of the die 58 and the second inclined surface 60ST of the punch 60, and the first convex surface 58SC of the die 58 and the second concave surface 60SD of the punch 60 form a convex vertical wall 50C, so that the blank material 62 flows between the first inclined surface 58ST and the second inclined surface 60ST. As a result, a compressive force is generated in the in-plane direction in the portion of the blank 62 corresponding to the convex flange 54C sandwiched between the first convex surface 58SC of the die 58 and the second concave surface 60SD of the punch 60.

[0084] The outer peripheral edge 62E of the blank 62 is sandwiched between the first outer wall surface 58SW of the first protrusion 66 and the second outer wall surface 60SW of the punch 60, and is bent to the same side as the vertical wall 50, thereby forming a return portion 56. As a result, the bending rigidity of the blank 62 in the portion corresponding to the protrusion flange 54C is increased along the width direction axis, and the occurrence of wrinkles in that portion is suppressed.

[0085] In the second embodiment, while forming the vertical wall 50, the outer peripheral edges 62E of the blank 62 that protrude to the left and right from the first protrusion 66 of the die 58 are sandwiched between the first outer wall surface 58SW of the first protrusion 66 and the second outer wall surface 60SW of the punch 60 and bent to the same side as the vertical wall 50. In other words, the manufacturing method according to the second embodiment simultaneously forms the vertical wall 50, the flange 54, and the return portion 56. The formation of the return portion 56 in this manner increases the bending rigidity of the blank 62 with respect to the width direction, which corresponds to the protrusion flange 54C. By increasing the bending rigidity of the blank 62 with respect to the width direction, which corresponds to the protrusion flange 54C where compressive force is generated in the in-plane direction, the occurrence of wrinkles in the protrusion flange 54C can be suppressed.

[0086] As described above, according to the second embodiment, since the convex vertical wall 50C and the convex flange 54C are formed while forming the return portion 56, the same effects as the first embodiment can be obtained. When viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C, the angle θ between the return portion 56 and the convex flange 54C is 90 degrees or more, so that the stress generated between the return portion 56 and the convex flange 54C can be suppressed, and thus the occurrence of cracks in the convex flange 54C can be suppressed. When viewed from a cross section perpendicular to the extending direction of the convex ridge portion 52C, the angle θ between the return portion 56 and the convex flange 54C is 120 degrees or less, the occurrence of wrinkles can be suppressed more reliably.

[0087] 3.Measurement method The plate thickness t is determined by measuring the plate thickness of the vertical wall and flange in the cross section with a return portion at 1 cm intervals along the extending direction, and taking the average of the obtained measurements as the representative value. The cross section with a return portion is defined as a cross section perpendicular to the extending direction of the curved ridge portion, within a range of ±10 mm from the center of the extending direction of the curved ridge portion in the curved region. The height h of the return portion is the length measured from the lower surface of the first flange to the upper end of the return portion in the cross section where the plate thickness t is measured. The angle θ between the return portion and the flange is defined as the angle between the return portion and the flange in the cross-section where the plate thickness t is measured. Vickers hardness can be measured by the Vickers hardness test specified in JIS Z 2244-1:2024. Specifically, first, the flange of a press-formed product is cut using a laser cutter or the like in a direction perpendicular to the direction of extension of the curved ridge, within a range of ±10 mm from the center of the extension direction of the curved ridge in the curved region, so that the length in the extension direction of the return portion is suitable for the Vickers hardness test, and a test piece is prepared. Next, each test piece is embedded in resin so that the cross section along the extension direction of the return portion of the obtained test piece is positioned on the surface, and the cross section is polished. Then, in accordance with JIS Z 2244-1:2024, the Vickers hardness is measured at 5 mm intervals in the extension direction of the return portion, with a test force of 300 gf (2.9 N) at the center or near the center in the thickness direction of this cross section, and at a point 1 / 4 of the thickness from the front and back surfaces of the plate, and the average of the obtained measured values ​​is taken as the representative value. If the indentation is large and it is not possible to measure the hardness at a point 1 / 4 of the thickness from both the front and back surfaces of the plate in accordance with JIS Z 2244-1:2024, only the center of the plate thickness should be measured. If it is difficult to position a cross section along the direction of extension of the return portion on the surface of the hardness test specimen, such as when the extension direction of the return portion is curved, each test specimen should be embedded in resin so that a cross section perpendicular to the extension direction is positioned on the surface, and the cross section should be polished. Then, the hardness should be measured similarly at the center or near the center of this cross section in the direction of plate thickness, and at a point 1 / 4 of the thickness from both the front and back surfaces of the plate thickness. At this time, hardness test specimens should be made every 5 cm in the direction of extension of the return portion, and the average of the obtained measurements should be used as the representative value. The tensile strength (MPa) of a press-formed product is approximately 3.3 times its Vickers hardness.

[0088] 4. Variations In the above embodiment, the case in which the press-formed product has a top plate was described, but the present invention is not limited to this and can also be applied to press-formed products that do not have a top plate. In the above embodiment, the case in which the press-formed product has a return portion has been described, but the present invention is not limited to this, and the return portion may be cut off and removed from the press-formed product. In the above embodiment, the case in which the return portion is provided along the flange over the entire range of the press-formed product has been described, but the present invention is not limited to this. The press-formed product may have a return portion in a part of the curved region that becomes a shrinking flange. By having a return portion in a part of the curved region of the press-formed product, the bending rigidity of the flange with respect to the width direction is increased compared to the case in which there is no return portion, so that the occurrence of wrinkles in the curved region can be suppressed. For example, it is preferable that the press-formed product has a return portion in the flange in the central region, which is 30% or more, 40% or more, 50% or more, 60% or more, and 70% or more of the total length, including the 50% position, with the entire range in the extending direction of the curved ridge in one curved region being 100%. Here, the central region is a region on the flange defined by an intersection line that divides the flange surface by a virtual plane passing through the center of curvature of the curved ridge and perpendicular to the extending direction of the curved ridge. By having a return portion in the above range of the curved region of the press-formed product, the bending rigidity of the flange with respect to the width direction can be more reliably increased, and the occurrence of wrinkles in the curved region can be more suppressed. It is preferable for the press-formed product to have a return portion on the flange throughout the entire curved region, as this can increase the bending rigidity of the flange along the width direction across the entire curved region. In the above embodiment, the case where the length H in the height direction of the press-formed product is the same throughout the entire range of the press-formed product was described, but the present invention is not limited to this, and the length H may differ in the direction in which the vertical wall of the press-formed product extends. In the above embodiment, the mold was described as having a die as the upper mold and a punch as the lower mold. However, the present invention is not limited to this, and the mold may also have a punch as the upper mold and a die as the lower mold. Although press-formed products 10A and 10B have been described above as embodiments, the present invention is not limited thereto. The present invention can be applied to press-formed products having a shrinking flange or a shrinking flange shape. More specifically, the present invention can be applied to press-formed products having a shrinking flange shape, which has a curved ridge that protrudes from the vertical wall toward the flange when viewed from the height direction, or a curved ridge that protrudes from the flange toward the vertical wall when viewed from the width direction. In other words, the present invention can be applied to press-formed products in which the top plate or flange is convex or S-shaped. Furthermore, although the case where the press-formed product 10A has an L-shaped outer shape in plan view has been described, it is not limited to the case where the linear regions intersect at right angles in plan view, but may also be a roughly L-shape, T-shape, or Y-shape where the linear regions intersect at obtuse or acute angles. The press-formed product 10A may also be cup-shaped or semi-cup-shaped with a flange. The press-formed product 10B may be a roughly L-shape, T-shape, or Y-shape in plan view, not limited to the I-shape, as long as the flange is convex in side view. Furthermore, although the above embodiment describes a case where the cross-sectional shape is hat-shaped, the present invention is not limited to this. For example, the top plate is not limited to a case where it is flat between a pair of flanges, but may also be curved between a pair of flanges, that is, the cross-sectional shape may be U-shaped with flanges.

[0089] In the above embodiment, the case of manufacturing a press-formed product by stamping has been described, but the present invention is not limited to this, and the product may also be formed by cam bending or pad bending. "Cam bending" refers to a process in which the press machine slide moves in a direction perpendicular or oblique to the main stroke, thereby applying a bending moment to the blank in a direction different from the main stroke. Hereinafter, pad bending will be described with reference to Figures 11A to 11C, which use the same reference numerals as Figure 3 for the same configuration. The die 30C shown in Figure 11A is a die for forming the press-formed product 10A according to Figure 1, and comprises an upper die 74 and a lower die punch 34. The only difference from Figure 3 is that a through hole 76 is provided in the center of the die 74, and a pad 78 is placed in the through hole 76. The pad 78 holds down the blank 36, and the surface in contact with the blank 36 is flat. First, as shown in Figure 11B, the pad 78 is moved downward, and the central part of the blank 36 is sandwiched and fixed between the pad 78 and the second protrusion 42 of the punch 34. That is, at this point, no bending moment is applied to the blank 36. Next, as shown in Figure 11C, the die 74 is moved downward to form the top plate 12, the vertical wall 14, and the flange 18. In this way, the manufacturing method according to this modified example simultaneously forms the vertical wall 14, the flange 18, and the return portion 28. That is, the mold 30C shown in Figures 11A to 11C forms the convex vertical wall 50C and the convex flange 54C while forming the return portion 56, so the same effects as in the first embodiment can be obtained.

[0090] In the above embodiment, the case of manufacturing a press-formed product has been described, but the press-formed product is not limited to a finished product, but may also be an intermediate product. That is, the press-formed product obtained in the above embodiment may be subjected to further processing. For example, the press-formed product may be subjected to trimming and further pressing. Trimming may include, for example, cutting the ends of the press-formed product or punching holes. Pressing may include, for example, additional stamping to prevent springback, bending to correct the angle between the top plate and the vertical wall, or drawing to further increase the height of the press-formed product.

[0091] 4. Simulation Results The effects of the present invention will be explained in detail based on the simulation results. (Simulation Model 1) As a blank, a simulation model 1 was prepared using a steel plate with a thickness of 2.0 mm and a Vickers hardness of 300 HV, in which the top plate, convex vertical wall, convex ridge, convex flange, and return portion were arranged in order on the outer side of the bend in the curved region of the press-formed product shown in Figure 1. In simulation model 1, the top plate, convex vertical wall, convex ridge, convex flange, and return portion were formed simultaneously without using a holder.

[0092] Height of the return portion h: 3mm Height of press-formed product: H: 20mm Bending radius R in the curved region: 20mm

[0093] (Simulation Model 2) As a blank, a simulation model 2 was prepared using a steel plate with a thickness of 1.2 mm and a Vickers hardness of 300 HV, in which the top plate, convex vertical wall, convex ridge, convex flange, and return portion of the curved region of the press-formed product shown in Figure 5 were arranged in order. In simulation model 2, the top plate, convex vertical wall, convex ridge, convex flange, and return portion were formed simultaneously without using a holder.

[0094] Height of the return portion: h: 16 mm Height of press-formed product: H: 30mm Bending radius R in the curved region: 100mm

[0095] (Simulation conditions) The angle θ between the return portion and the flange, and the wrinkles generated in the flange were evaluated by simulating the creation of a simulation model of the steel plate blank described above by press forming. The wrinkles were evaluated using the strain difference. The simulation was performed using general-purpose software (LS-Dyna, Ansys), and the mesh size of the blank was set to approximately 2 mm × 2 mm. The strain difference generated in the flange was defined as the difference in strain between the surface HF and the back surface HB at the position where the flange or protruding portion was deformed, as shown in Figure 12. Strain is the ratio of the deformation amount of the blank before deformation to the deformation amount of the blank after deformation.

[0096] The results are shown in Figures 13 and 14. Figure 13 shows the results for simulation model 1, and Figure 14 shows the results for simulation model 2. In Figures 13 and 14, the vertical axis shows the strain difference generated in the flange, and the horizontal axis shows the angle θ (degrees) between the return portion and the flange. Each plot shows the relationship between the angle θ and the maximum value of the strain generated in the flange. It was determined that wrinkle generation is suppressed when the strain difference is 0.05 or less. Note that in Figures 13 and 14, the data for an angle of 180 degrees between the return portion and the flange on the horizontal axis is from a simulation model without a return portion.

[0097] Figure 13 shows that in simulation model 1, i.e., a press-formed product having a curved ridge when viewed from the height direction, the difference in strain is reduced by having a return portion. Furthermore, it was confirmed that when the angle θ between the return portion and the flange is 150 degrees or less, the strain generated in the flange is even smaller, and the occurrence of wrinkles can be suppressed.

[0098] Figure 14 shows that in simulation model 2, i.e., a press-formed product having a curved ridge when viewed from the width direction, the difference in strain is reduced by having a return portion. Furthermore, it was confirmed that when the angle θ between the return portion and the flange is 120 degrees or less, the strain generated in the flange is even smaller, and the occurrence of wrinkles can be suppressed. [Explanation of Symbols]

[0099] 10A, 10B press-formed parts 12 Top plate 12F surface 14 Vertical walls 16. Ridge section 16C Curved ridge section 16CC Convex ridge line part 16CL Concave ridge line part 16L Straight ridge line 18 flange 20. First vertical wall 20C Convex vertical wall 20L straight first vertical wall 22. Second vertical wall 22D Concave vertical wall 22L straight second vertical wall 24 First flange 24C convex flange 24L Straight Flange 24F top surface 24B Bottom surface 26. Second flange 26D concave flange 26L Straight flange 28 Return section 30A, 30B molds 32 Dies 32S 1st molding surface 32SD 1st concave surface 32SS 1st outer surface 32SU 1st inner surface 32SW 1st outer wall surface 32STC First convex wall 32STD First concave wall surface 34 punches 34S 2nd molding surface 34SC 2nd convex surface 34SD 2nd concave surface 34ST 2nd slope 34SS 2nd outer surface 34SU 2nd inner surface 34STC Second convex wall 34STU 2nd concave wall 34SSC 2nd outer convex surface 34SW Second exterior wall 36 Blank 36E Outer edge 36F 1st page 36B 2nd side 38 First recess 40 First protrusion 42 Second protrusion 44. Second recess 46 Second outer convex part 48 Top plate 48C convex top plate 48F surface 48L linear top plate 50 vertical wall 50C Convex Vertical Wall 50L Straight vertical wall 52 Ridge section 52C Convex ridge line part 52L Straight ridge section 54 Flange 54C convex flange 54L Straight flange 54F top surface 54B Bottom side 56 Return section 58 Die 58S 1st molding surface 58SD 1st concave surface 58SC 1st convex surface 58ST 1st slope 58SW 1st outer wall surface 60 punches 60S 2nd molding surface 60SC 2nd convex surface 60SD 2nd concave surface 60ST 2nd slope 60SSC 2nd outer convex surface 60SW 2nd outer wall surface 62 Blank 62F 1st page 62E Outer edge 64 First recess 66 First protrusion 68 Second protrusion 70 Second recess 72 Second outer convex part CA Curved Region LA linear area θ angle

Claims

1. A press-formed product comprising a vertical wall and a flange, wherein the vertical wall and the flange are integrally formed via a ridge, The flange has a return portion in the curved region that becomes a contracted flange, The aforementioned return portion protrudes from the end of the flange opposite to the end of the flange connected to the vertical wall via the ridge portion, in the same direction as the vertical wall protruding in the thickness direction of the flange. The length h in the thickness direction of the return portion is longer than the plate thickness t of the flange. The aforementioned ridge portion has a curved ridge portion that, when viewed from the thickness direction, is curved in a direction that protrudes from the vertical wall toward the flange. A press-formed product in which, when viewed from a cross section perpendicular to the direction of extension of the curved ridge portion, the angle between the flange and the return portion is 90 degrees or more and 150 degrees or less.

2. A press-formed product comprising a vertical wall and a flange, wherein the vertical wall and the flange are integrally formed via a ridge, The flange has a return portion in the curved region that becomes a contracted flange, The aforementioned return portion protrudes from the end of the flange opposite to the end of the flange connected to the vertical wall via the ridge portion, in the same direction as the vertical wall protruding in the thickness direction of the flange. The length h in the thickness direction of the return portion is longer than the plate thickness t of the flange. The aforementioned ridge portion has a curved ridge portion that, when viewed from a direction perpendicular to the extending direction and the thickness direction of the aforementioned ridge portion, is curved in a direction that protrudes from the flange toward the vertical wall. A press-formed product in which, when viewed from a cross section perpendicular to the direction of extension of the curved ridge portion, the angle between the flange and the return portion is 90 degrees or more and 120 degrees or less.

3. The press-formed product according to claim 1 or 2, wherein the surface of the return portion facing the vertical wall is linear when viewed from a cross section perpendicular to the extending direction of the ridge portion.

4. The press-formed product according to claim 1 or 2, wherein the press-formed product is made of a metal plate, and the Vickers hardness of the metal plate is 300 HV or more.

5. A method for manufacturing a press-formed article according to claim 1 or 2, comprising the step of forming the ridge portion by pad bending, stamping, or cam bending.

6. A method for manufacturing a press-formed product according to claim 5, comprising a pressing step for simultaneously forming the vertical wall, the flange, and the return portion.

7. The method for manufacturing a press-formed product according to claim 6, wherein the pressing step uses a die integrally comprising a first concave surface for forming the top plate of the press-formed product, a first inclined surface for forming the vertical wall, a first convex surface for forming the flange, and a first outer wall surface for forming the return portion, thereby simultaneously forming the vertical wall, the flange, and the return portion in a single pressing step.

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