Press-formed product and method for manufacturing a press-formed product

Abstract

To prevent the occurrence of wrinkles in a region close to a flange portion in a curved surface portion of a press-formed article.SOLUTION: A press-formed article has a plate-shaped portion, a wall portion, and a flange portion. The wall portion has at least one curved surface portion in which a cross-sectional shape of a cut surface along the plate-shaped portion is an arcuate shape bulging outward in a radial direction. The at least one curved surface portion has a first curved surface portion and a second curved surface portion. The second curved surface portion is a portion closer to the flange portion than the first curved surface portion. A curvature radius of a cut surface of the second curved surface portion is configured to be smaller than a curvature radius of a cut surface of the first curved surface portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] ,

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

Background Art

[0002] In press-forming technology, Patent Document 1 discloses a technique for suppressing the generation of wrinkles in press-formed products.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors of the present disclosure have studied techniques for improving the appearance quality of press-formed products, such as reducing wrinkles. The press-formed product is configured to have a plate-like portion, a wall portion, and a flange portion, and a curved surface portion having an arc shape that bulges radially outward in a cross-sectional shape on a cut surface along the plate-like portion. As a result of the study, the inventors of the present disclosure have obtained the finding that wrinkles are likely to occur in a region of the curved surface portion of the press-formed product close to the flange portion.

[0005] In one aspect of the present disclosure, it is desirable to suppress the generation of wrinkles in a region of the curved surface portion of the press-formed product close to the flange portion.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a press-formed product having a plate-like portion, a wall portion, and a flange portion. The wall portion is plate-like and extends from the plate-like portion in a direction intersecting the plate-like portion. The flange portion is plate-like and protrudes from the tip of the wall portion. The wall portion has at least one curved surface portion whose cross-sectional shape at the cross-section along the plate-like portion is an arc shape that bulges radially outward. The at least one curved surface portion has a first curved surface portion and a second curved surface portion. The second curved surface portion is a portion closer to the flange portion than the first curved surface portion. The radius of curvature at the cross-section of the second curved surface portion is configured to be smaller than the radius of curvature at the cross-section of the first curved surface portion.

[0007] With this configuration, the circumferential length of the wall portion near the flange portion is longer than the circumferential length of the wall portion far from the flange portion. Therefore, during press working, the material flowing from the flange portion to the wall portion is dispersed circumferentially, suppressing buckling of the material. In other words, it provides a buckling suppression effect. As a result, the occurrence of wrinkles can be suppressed in the curved portion near the flange portion.

[0008] In one aspect of this disclosure, the wall portion may further have a stepped surface formed between the first curved portion and the second curved portion. The second curved portion may be located radially outward from the first curved portion.

[0009] With this configuration, the length of the outer surface of the wall in the extension direction is longer than the length of the outer surface of the wall in the extension direction when there is no step, by the amount of the step. As a result, the material flowing from the flange into the wall is also distributed in the extension direction of the wall, and the buckling suppression effect of the material is enhanced. Consequently, the occurrence of wrinkles can be further suppressed in the region of the curved surface that is close to the flange.

[0010] In one aspect of this disclosure, the wall portion may have multiple stepped surfaces. With this configuration, the length of the outer surface of the wall portion in the extension direction is longer by the number of stepped surfaces than the length of the outer surface of the wall portion in the extension direction when there is only one stepped surface. As a result, the material flowing from the flange portion into the wall portion is more easily dispersed, and the buckling suppression effect of the material is further enhanced. Consequently, the occurrence of wrinkles can be further suppressed in the region of the curved surface portion that is close to the flange portion.

[0011] In one aspect of this disclosure, the press-formed product may be an automobile body part. With this configuration, the occurrence of wrinkles can be suppressed in the curved portion of the automobile body part, particularly in the region close to the flange portion.

[0012] In one aspect of this disclosure, the press-formed product may have a bag shape with a recess. The wall portion may have a plurality of curved surfaces. The wall portion may further have a flat, straight edge portion connecting the plurality of curved surfaces. With such a configuration, the occurrence of wrinkles can be suppressed in the region of the curved surface portion that is close to the flange portion in the bag-shaped press-formed product.

[0013] One aspect of the present disclosure is a method for manufacturing a press-formed product having a predetermined target shape, using a first mold and a second mold. The above-mentioned press-formed product can be obtained by this manufacturing method. The first mold and the second mold each have a first molding section, a second molding section, and a third molding section. The first molding section is a section for forming a plate-like section. The second molding section is a section for forming a wall section. The third molding section is a section for forming at least one curved surface section. The method for manufacturing a press-formed product includes arranging a blank material between a first mold and a second mold that are spaced apart, and bringing the first mold and the second mold closer to each other with the blank material arranged between them.

[0014] With this configuration, the press-formed products detailed above can be manufactured. In other words, press-formed products in which the occurrence of wrinkles can be suppressed can be obtained. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a perspective view of a press-formed product in the first embodiment. [Figure 2] Figure 2A is a plan view of the press-formed product shown in Figure 1. Figure 2B is a cross-sectional view taken along line IIB-IIB in Figure 2A. [Figure 3] Figure 3A is a plan view conceptually illustrating the difference in radius of curvature and perimeter at the corner of the press-formed product shown in Figure 1. Figure 3B is a cross-sectional view taken along line IIIB-IIIB in Figure 3A. [Figure 4] Figure 4 is a cross-sectional view of a press molding apparatus for manufacturing the press-formed product shown in Figure 1. [Figure 5] Figure 5 is a perspective view of an intermediate formed by the press molding apparatus shown in Figure 4. [Figure 6] Figure 6A is a plan view of a press-formed product according to the second embodiment. Figure 6B is a cross-sectional view taken along VIB-VIB in Figure 6A. [Figure 7] Figure 7 is a perspective view of a press-formed product according to the third embodiment. [Modes for carrying out the invention]

[0016] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First Embodiment] [1-1. Composition of press-formed product] <Overview of press-formed products> The first embodiment relates to a press-formed product and a method for manufacturing a press-formed product. Figure 1 shows a perspective view of a press-formed product 10 formed using the manufacturing method for press-formed products according to the first embodiment.

[0017] After the drawing process of the manufacturing method of this embodiment, the press-formed product 10 is used as a component of an automobile body through necessary additional processes (for example, trimming process and bending process). As an example, the press-formed product 10 has a bag shape and is used as a rear floor having a space for storing a spare tire. Also, in the space of the press-formed product 10, as an example, in an electric vehicle (EV vehicle), in addition to the spare tire, tools, a safety vest, a charging cable, etc. can also be stored. The press-formed product 10 and its manufacturing method can be applied not only to the rear floor but also to various other parts and products.

[0018] The press-formed product 10 is obtained by performing press forming (drawing process) including drawing and bending on a blank material 50 made of a steel sheet. The material of the blank material 50 used for the press-formed product 10 is, as an example, a steel sheet with alloyed zinc plating. The blank material 50 can have a thickness of 0.6 mm to 1.4 mm. In this embodiment, the thickness of the blank material 50 is 0.6 mm.

[0019] <Overall shape of the press-formed product> The press-formed product 10 has a deep bag shape. The bag shape is a shape capable of enclosing an object therein. This enclosing means holding the object by the bottom wall and the side wall. In other words, the bag shape means a configuration including a bottom wall and one or more side walls.

[0020] The size of the bag-shaped portion (the portion other than the flange portion 16 described later) of the press-formed product 10 is, for example, about 600 mm in width, about 200 mm in depth, and about 180 mm in depth. Hereinafter, the direction along the depth of the press-formed product 10 (the vertical direction in FIG. 1) is referred to as the depth direction X. The depth of the press-formed product 10 is 80 mm or more. The press forming method of drawing the blank material 50 into a deep bag shape is also called deep drawing.

[0021] The press-formed product 10 has a top plate portion 12, a vertical wall portion 14, and a flange portion 16. In Figure 1, for the sake of explanation, the top plate portion 12 is shown as the upper part of the press-formed product 10, but the press-formed product 10 is used in a position that is upside down from the position shown in Figure 1. For this reason, the top plate portion 12 is sometimes referred to as the bottom wall portion, focusing on the state of use. In this embodiment, the space enclosed by the top plate portion 12 and the vertical wall portion 14 is a space for storing a spare tire, tools, a safety vest, a charging cable, etc.

[0022] The top plate portion 12 is substantially flat. The top plate portion 12 is substantially rectangular in shape, with two adjacent corners rounded in plan view to form the top plate curved portion 18, which will be described later. However, the shape of the top plate portion 12 may generally be other polygonal shapes in plan view. The top plate portion 12 has two curved top plate curved portions 18 on its outer circumference. In this embodiment, the shape of the top plate curved portion 18 is an arc shape in a perfect circle. However, the shape of the top plate curved portion 18 may be an arc shape in an ellipse, a composite curve shape, etc. The top plate portion 12 may have irregularities or holes formed on it as needed. Note that the plane containing most of the top plate portion 12 may be simply referred to as the top plate portion 12 below.

[0023] The vertical wall portion 14 is a part that extends from the top plate portion 12 in a direction intersecting the top plate portion 12. The vertical wall portion 14 is plate-shaped. In this embodiment, the vertical wall portion 14 extends from the outer circumference of the top plate portion 12, including the two top plate curved portions 18. Hereinafter, as shown in Figure 2B, the direction in which the vertical wall portion 14 extends will be referred to as the extension direction Y. In this embodiment, the extension direction Y is inclined with respect to the depth direction X. Note that if the vertical wall portion 14 is not inclined with respect to the depth direction X, the extension direction Y coincides with the depth direction X. The vertical wall portion 14 is inclined to spread outward relative to the top plate portion 12.

[0024] The flange portion 16 protrudes from the tip of the vertical wall portion 14. In other words, the flange portion 16 extends outward from the tip of the vertical wall portion 14. The flange portion 16 extends generally parallel to the top plate portion 12. The flange portion 16 is plate-shaped. The flange portion 16 is generally partially annular in its plan view.

[0025] The vertical wall section 14 has three flat, straight edge sections 20 and two corner sections 22. Each corner section 22 is a band-shaped region extending from the top plate curved section 18 with approximately the same width. Each straight edge section 20 connects a plurality of curved sections 24, which will be described later. Each straight edge section 20 has a straight cross-sectional shape in the cut surface along the top plate section 12. Each straight edge section 20 is the part of the vertical wall section 14 other than the corner sections 22.

[0026] As shown in Figure 1, the press-formed product 10 of this embodiment is symmetrical, so below we will focus only on one side and describe one corner portion 22. However, the press-formed product 10 does not have to be symmetrical.

[0027] The corner section 22 has a first region 30 close to the top plate section 12 and a second region 32 close to the flange section 16. The first region 30 is connected to the top plate section 12 by the top plate curved section 18, and the second region 32 is connected to the flange section 16. In other words, the top plate section 12 and the first region 30 are arranged adjacent to each other, and the flange section 16 and the second region 32 are arranged adjacent to each other. Furthermore, the first region 30 and the second region 32 are arranged side by side along the extension direction Y, separated by a stepped surface 38 which will be described later. In the corner section 22 shown in Figure 1, the upper half of the depth in the depth direction X is the first region 30, and the lower half is the second region 32.

[0028] The curved surface portion 24 has a first curved surface portion 34 and a second curved surface portion 36. The first curved surface portion 34 is included in the first region 30. The first curved surface portion 34 has a first arc-shaped cross-section in which the cross-sectional shape of the cut surface along the top plate portion 12 bulges radially outward. The second curved surface portion 36 is included in the second region 32. The second curved surface portion 36 has a second arc-shaped cross-section in which the cross-sectional shape of the cut surface along the top plate portion 12 bulges radially outward.

[0029] The cross-sectional plane along the top plate portion 12 is a cross-sectional plane perpendicular to the depth direction X. In this embodiment, the shapes of the first and second arc-shaped cross-sections are constant at any position in the depth direction X. The shapes of the first and second arc-shaped cross-sections are not limited to arcs in a perfect circle, but may also be other cross-sectional shapes such as outwardly curving ellipses or composite curves.

[0030] The vertical wall portion 14 has a stepped surface 38 formed between the first curved surface portion 34 and the second curved surface portion 36. The stepped surface 38 is a planar portion connecting the first curved surface portion 34 and the second curved surface portion 36, and extends generally parallel to the top plate portion 12. In this embodiment, the stepped surface 38 is formed at an intermediate position in the depth direction X of the corner portion 22.

[0031] The second curved surface portion 36 is located radially outward from the first curved surface portion 34. Here, "radial direction" refers to the radial direction of the arc in the first and second arc-shaped cross-sections. As shown in Figure 2B, when the corner portion 22 is viewed along the extension direction Y, the second curved surface portion 36 protrudes outward (to the right in Figure 2B) from the first curved surface portion 34.

[0032] The radius of curvature R2 (described in detail later) of the second curved surface 36 along the top plate portion 12 is smaller than the radius of curvature R1 of the first curved surface 34 along the top plate portion 12. In this embodiment, R1 and R2 are constant at any position in the depth direction X. However, the radii of curvature of the first curved surface 34 and the second curved surface 36 are not constant and may be variable in the depth direction X. In this embodiment, R1 is 200 mm and R2 is 100 mm. However, R1 and R2 are not limited to these values, and it is sufficient that R2 is smaller than R1.

[0033] [1-2. Press forming equipment] Figure 4 is a cross-sectional view of a press forming apparatus for forming a press-formed product 10. The press forming apparatus comprises a die 60, a punch 62, and a blank holder 64. The die 60 and the punch 62 are configured to be displaceable relative to the depth direction X of the press-formed product 10 by a drive mechanism (not shown). In this embodiment, the die 60 may be displaced in the depth direction X, the punch 62 may be displaced in the depth direction X, or both the die 60 and the punch 62 may be displaced in the depth direction X.

[0034] The die 60 and the punch 62 work together to perform press forming. The die 60 and the punch 62 face each other, spaced apart. The die 60 has a concave shape and has a die hole 66 into which the top of the punch 62 is inserted. The punch 62 has a convex shape.

[0035] The die 60 and punch 62 each have a shape that conforms to the shape of the press-formed product 10. Specifically, the die 60 and punch 62 each have a first forming section 70a, 70b, a second forming section 72a, 72b, and a third forming section 74a, 74b. The first forming sections 70a, 70b are for forming the top plate section 12. The second forming sections 72a, 72b are for forming the vertical wall section 14. The third forming sections 74a, 74b are for forming the first curved surface section 34 and the second curved surface section 36.

[0036] The blank holder 64 works in cooperation with the die 60 to clamp and fix the blank material 50. The blank holder 64 faces the die 60. A through hole corresponding to the punch 62 is formed in the center of the blank holder 64.

[0037] [1-3. Method for manufacturing press-formed products] Next, a method for manufacturing the press-formed product 10 will be described. In this embodiment, the following press forming is performed to manufacture the press-formed product 10.

[0038] In this embodiment, press forming (the forming process described later) is performed in one step. The inventors confirmed through simulation analysis that wrinkles and cracks were suppressed even when press forming was performed in one step in this manner. However, press forming may be performed in multiple steps rather than one. In this embodiment, press forming is performed by lowering the die 60. However, the punch 62 may be raised, or both the die 60 and the punch 62 may be displaced.

[0039] The method for manufacturing the press-formed product 10 includes a positioning step of placing a blank material 50 between a spaced-apart die 60 and a punch 62, and a forming step of bringing the die 60 and the punch 62 closer together (for example, meshing them) while the blank material 50 is positioned between the die 60 and the punch 62.

[0040] First, in the placement process, the blank material 50 is placed on the upper surface of the blank holder 64. This positions the blank material 50 between the spaced-apart die 60 and punch 62.

[0041] Next, in the molding process, as the die 60 descends, the die 60 and the blank holder 64 move closer together, and the blank material 50 is fixed in place, sandwiched between the blank holder 64 and the die 60.

[0042] Furthermore, as the die 60 descends, the die 60 and the blank holder 64 descend together while holding the blank material 50. As the die 60 descends further, the first forming portion 70b of the punch 62 comes into contact with the blank material 50. As the die 60 descends further, the blank material 50 is pushed into the die hole 66 by the punch 62. When the die 60 reaches its bottom dead center, the top plate portion 12 is formed at the portion where the blank material 50 is held by the first forming portions 70a and 70b. At the same time, the vertical wall portion 14 is formed at the portion where the blank material 50 is held by the second forming portions 72a and 72b, and the first curved portion 34 and the second curved portion 36 are formed at the portion where the blank material 50 is held by the third forming portions 74a and 74b. In addition, the flange portion 16 is formed at the portion where the blank material 50 is held by the blank holder 64 and the die 60.

[0043] In this way, the intermediate body 52 shown in Figure 5 is formed. The intermediate body 52 then undergoes subsequent trimming and bending processes to form bent portions for reinforcing the flange portion 16 and holes for attaching the press-formed product 10 to a predetermined location, thereby forming the press-formed product 10.

[0044] [1-4. Difference in radius of curvature and perimeter at corners] The following will explain the difference in radius of curvature and perimeter at the corner section with reference to Figures 3A and 3B. Before that, however, we will explain the concept of "central angle," which will be of interest in this explanation.

[0045] In press forming, the material constituting the blank material 50 is stretched such that the portion corresponding to the flange portion 16 flows into the portion corresponding to the vertical wall portion 14 along the extension direction Y. This movement of the material will be conceptually explained by focusing on the material constituting the target area. The target area is the portion of the blank material 50 that constitutes a part of the flange portion 16 and a part of the vertical wall portion 14 near the corner portion 22. The target area is generally a partially annular region of the blank material 50. In the following explanation, the extension direction Y will also be referred to as the "axial direction".

[0046] During press forming, the target portion of the blank material 50 flows from the portion corresponding to the flange portion 16 along the axial direction to the region of the portion corresponding to the vertical wall portion 14 that has the same central angle as the target portion, and moves axially within the strip-shaped region. Here, the region having the same central angle is, in the example shown in Figure 3A, a surface (for example, the first curved surface portion 34) obtained by stacking sector-shaped arc portions, each at a predetermined distance from the center point O1, along the extension direction Y at any position in the extension direction Y. However, the region having the same central angle is not limited to sector-shaped arc portions, but also includes parts formed from the target portion (for example, a continuum which is a combination of the second curved surface portion 36 and a pair of planar portions 40). In other words, the region having the same central angle is the band-shaped region from the flange portion 16 to the top plate portion 12 in the corner portion 22. In this embodiment, the region having the same central angle is the band-shaped region Z (see Figure 1) between the two dashed lines in the corner portion 22.

[0047] Based on the above, it is possible to define that the region of the corner portion 22 that should be considered in order to suppress the occurrence of wrinkles is not limited to curved surfaces such as the first curved surface portion 34 and the second curved surface portion 36, but rather regions having the same central angle.

[0048] Next, the difference in radius of curvature at the corner section 22 will be explained with reference to Figures 3A and 3B. Figure 3A shows a plan view of the corner section 22, which is a model assuming that the portion of the outer surface of the corner section 22 excluding the stepped surface 38 coincides with the depth direction X. The difference in radius of curvature here refers to the difference between the radius of curvature R1 of the first curved surface section 34 and the radius of curvature R2 of the second curved surface section 36. As mentioned above, the radius of curvature R2 of the second curved surface section 36 is set to be smaller than the radius of curvature R1 of the first curved surface section 34.

[0049] The difference in circumference caused by the difference in radius of curvature at the corner section 22 is the difference between the circumference L2 of the second region 32 and the circumference L1 of the first region 30.

[0050] As shown in Figure 3A, the first region 30 has a first curved surface portion 34 extending in a cross section that forms an arc within a sector having a central angle θ1 (for example, 90 degrees) and a predetermined radius R1 (for example, 200 mm). The center point of the first curved surface portion 34 in the thus defined first region 30 is indicated by O1.

[0051] In the model shown in Figure 3A, the first region 30 and the first curved surface 34 coincide. Therefore, the perimeter L1 of the first region 30 coincides with the length of the arc obtained by cutting the first curved surface 34 with a plane perpendicular to the depth direction X.

[0052] In contrast, as shown in the figure, the second region 32 has a second curved surface portion 36 that extends in a cross section forming an arc within a sector having a central angle θ2 (for example, 90 degrees) and a predetermined R2 (for example, 100 mm). The center point of the second curved surface portion 36 in the second region 32 defined in this way is indicated by O2.

[0053] The second region 32 includes a pair of planar portions 40 located on both sides of the second curved surface portion 36, so as to sandwich the second curved surface portion 36 in the circumferential direction. Therefore, the second region 32 is configured as a continuum between the second curved surface portion 36 and the pair of planar portions 40.

[0054] Therefore, the perimeter L2 of the second region 32 is the sum of the arc and a pair of straight lines obtained by cutting the second curved portion 36 and the flat portion 40 with a plane perpendicular to the depth direction X.

[0055] As shown in Figure 3A, the first region 30 and the second region 32 have the same central angle θ1, and R2 is smaller than R1. Therefore, the perimeter L2 in the second region 32 is longer than the perimeter L1 in the first region 30.

[0056] The above explanation focused on the corner portion 22 and described the difference in perimeter between the first region 30 and the second region 32. However, it is also possible to focus on the entire press-formed product 10, rather than the corner portion 22, and explain the difference in perimeter between the region of the vertical wall portion 14 that is close to the top plate portion 12 and the region that is close to the flange portion 16.

[0057] Here, we have described the difference in radius of curvature and perimeter in a hypothetical state where the outer surface of the corner portion 22 is not inclined with respect to the depth direction X. However, the relationship between the difference in radius of curvature and perimeter between the first region 30 and the second region 32, that is, the characteristic configuration in which the perimeter of the region of the corner portion 22 closer to the flange portion 16 is longer than the perimeter of the region closer to the top plate portion 12, and the radius of curvature in the region closer to the flange portion 16 is smaller than the radius of curvature in the region closer to the top plate portion 12, can also be applied as a similar characteristic configuration when the outer surface of the corner portion 22 is inclined with respect to the depth direction X.

[0058] [1-5. Effects] The inventors investigated the effectiveness of various prototypes, including the press-formed product 10 of this embodiment, through simulations.

[0059] First, the inventor proposed a preliminary prototype in which the radius of curvature of the corner portion 22, which was the target shape, was uniformly set to 100 mm. As a result of analyzing the preliminary prototype through simulation, it was found that cracks may occur at the boundary between the top plate portion 12 and the corner portion 22, and at the punch shoulder portion, which is the surrounding area.

[0060] Therefore, the inventor proposed a second prototype in which the radius of curvature of the corner portion 22 was uniformly set to 200 mm. However, as a result of analyzing the second prototype by simulation, it was found that although the possibility of cracking at the punch shoulder portion was reduced, there was a possibility of wrinkles occurring in the second region 32 of the corner portion 22. The inventor considered that these wrinkles were caused by the material concentrating in the second region 32 as the material flows from the flange portion 16 to the vertical wall portion 14, and as a result, the excess material in the second region 32 buckling.

[0061] Based on this background, the inventor noticed that the movement of the material differs between the area of ​​the corner portion 22 closest to the top plate portion 12 (first region 30) and the area closest to the flange portion 16 (second region 32). The inventor then considered setting different radii of curvature for the first region 30 and the second region 32. Specifically, the inventor set R1 to 200 mm in the first region 30 to prevent cracking, and set R2 to 100 mm in the second region 32, the same as the first prototype, to prevent wrinkling. Furthermore, the inventor noticed that by setting the radii of curvature of the corner portion 22 in this way, the perimeter L2 in the second region 32 becomes longer than the perimeter L1 in the first region 30.

[0062] The inventors developed the press-formed product 10 of this embodiment in this manner. The inventors then performed a simulation analysis of the press-formed product 10 and confirmed that the possibility of cracking occurring in the punch shoulder portion and the possibility of wrinkles occurring in the second region 32 were reduced.

[0063] According to the embodiments described in detail above, the following effects can be obtained. (1a) In the press-formed product 10 of the first embodiment, at the corner portion 22, the circumferential length L2 of the second region 32 is longer than the circumferential length L1 of the first region 30. Therefore, during press forming, the volume of material occupying the second region 32 is greater than that of the first region 30, and the material flowing from the flange portion 16 to the vertical wall portion 14 is dispersed circumferentially in the second region 32, suppressing buckling of the material. As a result, the occurrence of wrinkles in the second region 32 can be suppressed.

[0064] (1b) In the press-formed product 10 of this embodiment, the radius of curvature R1 of the first curved surface portion 34 is large, and the radius of curvature R1 of the second curved surface portion 36 is small. As a result, material flows more easily to the punch shoulder, the strain is dispersed, and the occurrence of cracks in the punch shoulder can be suppressed.

[0065] (1c) The press-formed product 10 of this embodiment has R1 of 200 mm and R2 which is smaller than R1, at 100 mm. Therefore, as described above, it is possible to simultaneously suppress the occurrence of cracks that may occur in the punch shoulder and the occurrence of wrinkles that may occur in the second region 32.

[0066] (1d) The press-formed product 10 of this embodiment has a stepped surface 38 formed between the first curved surface 34 and the second curved surface 36. As a result, the length of the outer surface of the corner portion 22 in the extension direction Y is longer by the amount of the step than if there were no stepped surface 38 on the corner portion 22. As a result, the material flowing from the flange portion 16 to the corner portion 22 is also distributed in the extension direction Y of the corner portion 22, and the buckling suppression effect of the material is enhanced. As a result, the occurrence of wrinkles in the second region 32 can be further suppressed.

[0067] (1e) In the press-formed product 10 of this embodiment, the length of the outer surface of the corner portion 22 in the extension direction Y (i.e., the length along the extension direction Y between the top plate curve portion 18 and the flange portion 16) is longest when the circumferential centers of the corner portion 22 in each extension direction Y are connected. That is, the length of the outer surface of the corner portion 22 is longest at the position of the cross section shown in Figure 2B. Therefore, the occurrence of wrinkles can be efficiently suppressed in the circumferential central portion of the second region 32, where the occurrence of wrinkles is most likely.

[0068] (1f) Generally, in deep drawing, it is necessary to divide the process into two or more steps in order to achieve the height in the depth direction X, in order to suppress wrinkles and cracks. In the manufacturing method of the press-formed product 10 of this embodiment, a press-formed product 10 with suppressed wrinkles and cracks can be formed in one step.

[0069] [1-6. Correspondence between terms] In this embodiment, the top plate portion 12 corresponds to the plate-like portion in this disclosure, and the vertical wall portion 14 corresponds to the wall portion in this disclosure. Also, in this embodiment, the die 60 corresponds to the first mold in this disclosure, and the punch 62 corresponds to the second mold in this disclosure.

[0070] [2. Second Embodiment] [2-1. Composition of press-formed products] In the second embodiment, elements common to the first embodiment are referred to by the same reference numerals or names, thereby omitting redundant explanations, and only the different elements are described in detail.

[0071] The press-formed product 10 of the first embodiment had one stepped surface 38. In contrast, the press-formed product 100 of the second embodiment, shown in Figures 6A and 6B, differs from the first embodiment in that the corner portion 22 has multiple stepped surfaces 106.

[0072] In this embodiment, the second region 32 is divided into two sub-regions aligned in the extension direction Y. Therefore, the corner portion 22 of this embodiment is divided into three sub-regions aligned along the extension direction Y. Step surfaces 38 and 106 are formed between adjacent sub-regions.

[0073] In this embodiment, the second region 32 is divided into a second a region 102, which is the region close to the top plate portion 12, and a second b region 104, which is the region close to the flange portion 16. The second a region 102 is aligned with the first region 30 along the extension direction Y via a stepped surface 38, and the second b region 104 is connected to the flange portion 16. The stepped surface 106 is formed between the second a region 102 and the second b region 104.

[0074] The second a region 102 and the second b region 104, like the first region 30 and the second region 32 in the first embodiment, have a second a curved surface portion 108 and a second b curved surface portion 110, respectively. The radius of curvature of the second b curved surface portion 110 is smaller than the radius of curvature of the second a curved surface portion 108. Furthermore, the second b curved surface portion 110 is located radially outward from the second a curved surface portion 108.

[0075] Thus, the relationship between the second a region 102 and the second b region 104 in this embodiment has the same characteristics as the relationship between the first region 30 and the second region 32 in the first embodiment. That is, the radius of curvature of the region in the second region 32 that is close to the flange portion 16 (second b region 104) is smaller than the radius of curvature of the region that is close to the top plate portion 12 (second a region 102).

[0076] Therefore, the relationship between the difference in radius of curvature and the difference in perimeter between the first region 30 and the second region 32 in the first embodiment can also be applied to the relationship between the difference in radius of curvature and the difference in perimeter between the seconda region 102 and the secondb region 104 in this embodiment. Thus, the perimeter of the secondb region 104 is longer than the perimeter of the seconda region 102.

[0077] In this embodiment, the second region 32 is divided into two subregions aligned in the extension direction Y. However, the second region 32 may be divided into three or more subregions. In this case, each of the two subregions divided in the second region 32 may be further divided into two: the region closer to the top plate portion 12, or the region closer to the flange portion 16. Each of these further divided subregions has characteristics similar to the relationship between the first region 30 and the second region 32 in the first embodiment. That is, among the further divided regions, the radius of curvature of the region closer to the flange portion 16 is smaller than that of the region closer to the top plate portion 12. Therefore, among the further divided regions, the perimeter of the region closer to the flange portion 16 can be made longer than the perimeter of the region closer to the top plate portion 12.

[0078] [2-2. Effects] (2a) In this embodiment, the press-formed product 100 has more stepped surfaces at the corner portion 22 than in the first embodiment. Therefore, the length of the outer surface of the corner portion 22 in the extension direction Y is longer than the length of the outer surface of the corner portion 22 in the first embodiment by the amount of the stepped surfaces. As a result, the material flowing from the flange portion 16 into the corner portion 22 is more easily dispersed, and the buckling suppression effect of the material is further enhanced. As a result, the occurrence of wrinkles can be further suppressed in the region of the curved surface portion 24 that is close to the flange portion 16.

[0079] (2b) In addition, in the press-formed product 100 of this embodiment, the circumference of each region is longer in the region closer to the flange portion 16, similar to the first embodiment. Therefore, it produces the same effects as described in (1a) to (1f).

[0080] [3. Third Embodiment] [3-1. Composition of press-formed products] In this embodiment, elements common to the first and second embodiments are referred to by the same reference numerals or names, thereby omitting redundant explanations, and only the different elements are described in detail.

[0081] In the press-formed products 10 and 100 of the first and second embodiments, as shown in Figures 1 and 6, the first region 30 and the second region 32 are aligned along the extension direction Y via a stepped surface 38 at the corner portion 22. Also, the second a region 102 and the second b region 104 are aligned via a stepped surface 106. In other words, in the press-formed product 10 and 100, the corner portion 22 has a discontinuous inclined surface having at least one stepped surface. Furthermore, in the press-formed products 10 and 100 of the first and second embodiments, the radius of curvature of the curved portion 24 is constant at any position in the depth direction X in each region.

[0082] In contrast, as shown in Figure 7, in the press-formed product 200 of the third embodiment, the corner portion 22 does not have stepped surfaces 38,106, and the inclined surface of the corner portion 22 is a continuous surface in the extension direction Y.

[0083] Furthermore, in the press-formed product 200 of this embodiment, the radius of curvature of the curved portion 24 gradually decreases as it moves from the top plate portion 12 towards the flange portion 16. That is, the radius of curvature of the curved portion 24 changes to continuously decrease as it moves from the top plate portion 12 towards the flange portion 16 in the depth direction X. Therefore, the curved portion 24 has a tapered shape that narrows towards the flange portion 16. For example, the curved portion 24 may be a part of a conical surface having its apex near the flange portion 16.

[0084] In this embodiment as well, similar to the first embodiment, the radius of curvature in the region close to the flange portion 16 of the corner portion 22 is smaller than the radius of curvature in the region close to the top plate portion 12. Therefore, the relationship between the difference in radius of curvature and the difference in circumference between the first region 30 and the second region 32 in the first embodiment can also be applied to the corner portion 22, which does not have stepped surfaces 38,106 as in this embodiment. Thus, in the corner portion 22, the circumference of the region close to the flange portion 16 is longer than the circumference of the region close to the top plate portion 12.

[0085] [3-2. Effects] In this embodiment, the press-formed product 200, similar to the first and second embodiments, has a longer perimeter in the area of ​​the corner portion 22 closest to the flange portion 16 than in the area of ​​the top plate portion 12. Therefore, it achieves the same effects as described in (1a) to (1c) and (1e) to (1f) above.

[0086] [4. Other Embodiments] While embodiments of this disclosure have been described above, it goes without saying that this disclosure is not limited to the embodiments described above and can take various forms.

[0087] The functions of one component in the above embodiment may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Furthermore, some parts of the configuration of the above embodiment may be omitted. Also, at least some parts of the configuration of the above embodiment may be added to, substituted for, or otherwise replaced with the configuration of other above embodiments.

[0088] [Technical Concept Disclosed in This Specified Specification] [Item 1] Plate-shaped part and A plate-shaped wall portion extending from the plate-shaped portion in a direction intersecting the plate-shaped portion, A plate-shaped flange portion protruding from the tip of the aforementioned wall portion, It has, The wall portion has at least one curved surface portion whose cross-sectional shape at the cut surface along the plate-like portion is an arc shape that bulges radially outward, The at least one curved surface portion comprises a first curved surface portion and a second curved surface portion that is closer to the flange portion than the first curved surface portion. A press-formed product in which the radius of curvature at the cross-section of the second curved surface is smaller than the radius of curvature at the cross-section of the first curved surface.

[0089] [Item 2] The wall portion further has a stepped surface formed between the first curved portion and the second curved portion, The press-formed product according to item 1, wherein the second curved portion is located radially outward from the first curved portion.

[0090] [Item 3] The wall portion is a press-formed product according to item 2, having a plurality of stepped surfaces.

[0091] [Item 4] The aforementioned press-formed product is a body part for an automobile, as described in any one of items 1 to 3.

[0092] [Item 5] The aforementioned press-formed product has a bag shape with a recess, The wall portion has a plurality of the at least one curved portion, The press-formed product according to any one of items 1 to 4, wherein the wall portion further has a flat, straight edge portion connecting the plurality of curved portions.

[0093] [Item 6] A method for manufacturing a press-formed product having a predetermined target shape, using a first mold and a second mold, The aforementioned press-formed product is Plate-shaped part and A plate-shaped wall portion extending from the plate-shaped portion in a direction intersecting the plate-shaped portion, A plate-shaped flange portion protruding from the tip of the aforementioned wall portion, It has, The wall portion has at least one curved surface portion whose cross-sectional shape at the cut surface along the plate-like portion is an arc shape that bulges radially outward, The at least one curved surface portion comprises a first curved surface portion and a second curved surface portion that is closer to the flange portion than the first curved surface portion. The radius of curvature at the cross-section of the second curved surface is configured to be smaller than the radius of curvature at the cross-section of the first curved surface. The first mold and the second mold are, respectively, A first molding section for forming the plate-like portion, A second molding section for forming the aforementioned wall portion, A third molding section for forming the aforementioned at least one curved surface portion, It has, Placing a blank material between the separated first mold and the second mold, With the blank material positioned between the first mold and the second mold, the first mold and the second mold are brought into close proximity to each other. A method for manufacturing press-formed products including [specific components].

[0094] [Item 7] The wall portion further has a stepped surface formed between the first curved portion and the second curved portion, The method for manufacturing a press-formed product according to item 6, wherein the second curved surface portion is located radially outward from the first curved surface portion.

[0095] [Item 8] The method for manufacturing a press-formed product according to item 7, wherein the wall portion has a plurality of stepped surfaces.

[0096] [Item 9] The method for manufacturing a press-formed article as described in any one of items 6 to 8, wherein the press-formed article is a body part of an automobile. [Explanation of symbols]

[0097] 10...Press-formed part, 12...Top plate section, 14...Vertical wall section, 16...Flange section, 24...Curved surface section, 30...First region, 32...Second region, 34...First curved surface section, 36...Second curved surface section, 38...Stepped surface, 50...Blank material, 60...Die, 62...Punch, 70a, 70b...First forming section, 72a, 72b...Second forming section, 74a, 74b...Third forming section, R1, R2...Radius of curvature.

Claims

1. Plate-shaped part and A plate-shaped wall portion extending from the plate-shaped portion in a direction intersecting the plate-shaped portion, A plate-shaped flange portion protruding from the tip of the aforementioned wall portion, It has, The wall portion has a flat, straight edge portion and at least one curved portion whose cross-sectional shape at the cut surface along the plate-like portion is an arc shape that bulges radially outward. The at least one curved surface portion has a first curved surface portion and a second curved surface portion that is closer to the flange portion than the first curved surface portion, and the first curved surface portion and the second curved surface portion are connected to the straight edge portion in the same plane as the straight edge portion. A press-formed product in which the radius of curvature at the cross-section of the second curved surface is smaller than the radius of curvature at the cross-section of the first curved surface.

2. The wall portion further has a stepped surface formed between the first curved portion and the second curved portion, The press-formed product according to claim 1, wherein the second curved portion is located radially outward from the first curved portion.

3. The wall portion has a plurality of stepped surfaces, as described in claim 2.

4. The press-formed product is a body part for an automobile, as described in any one of claims 1 to 3.

5. The aforementioned press-formed product has a bag shape with a recess, The wall portion has a plurality of the at least one curved portion, The straight edge portion is configured to connect the plurality of curved portions, as described in any one of claims 1 to 3.

6. A method for manufacturing a press-formed product having a predetermined target shape, using a first mold and a second mold, The aforementioned press-formed product is Plate-shaped part and A plate-shaped wall portion extending from the plate-shaped portion in a direction intersecting the plate-shaped portion, A plate-shaped flange portion protruding from the tip of the aforementioned wall portion, It has, The wall portion has a flat, straight edge portion and at least one curved portion whose cross-sectional shape at the cut surface along the plate-like portion is an arc shape that bulges radially outward. The at least one curved surface portion has a first curved surface portion and a second curved surface portion that is closer to the flange portion than the first curved surface portion, and the first curved surface portion and the second curved surface portion are connected to the straight edge portion in the same plane as the straight edge portion. The radius of curvature at the cross-section of the second curved surface is configured to be smaller than the radius of curvature at the cross-section of the first curved surface. The first mold and the second mold are, respectively, A first molding section for forming the plate-like portion, A second molding section for forming the aforementioned wall portion, A third molding section for forming the at least one curved surface portion, It has, Placing a blank material between the separated first mold and the second mold, With the blank material positioned between the first mold and the second mold, the first mold and the second mold are brought close to each other, A method for manufacturing press-formed products including [specific components].

7. The wall portion further has a stepped surface formed between the first curved portion and the second curved portion, The method for manufacturing a press-formed product according to claim 6, wherein the second curved portion is located radially outward from the first curved portion.

8. The method for manufacturing a press-formed product according to claim 7, wherein the wall portion has a plurality of stepped surfaces.

9. The method for manufacturing a press-formed product according to any one of claims 6 to 8, wherein the press-formed product is a body part for an automobile.

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