Method for manufacturing press-formed product having asymmetric flange portion

Abstract

To provide a manufacturing method for a press-molded product having a pair of asymmetrical flange parts that can prevent the press-formed product in which shapes of the flange parts are bilaterally asymmetric in a width direction from being warped after demolded, while keeping the shapes in a desired target shape.SOLUTION: A manufacturing method for a press-molded product having asymmetrical flange parts according to the present invention, manufactures, into a target shape, a press-molded product 1 which comprises a top plate part 3, a pair of vertical wall parts 5 connected to the top plate part 3, and a pair of flange parts 7 connected to the vertical wall parts 5, wherein shapes of the pair of flange parts 7 are bilaterally asymmetric in a width direction. The manufacturing method comprises: a blank preparation step of preparing a blank 11 which at least partially has a flange corresponding part 11a wider than a flange corresponding part 19a of a developed blank developed in a target shape; a press-molding step of press-molding an intermediate product 13 in which flange parts 15 are wider than a width of the target shape using the prepared blank 11; and a trimming step of trimming the wide flange parts 15 in the intermediate product 13 into the target shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a press-formed product having a hat-shaped cross section, which includes a top plate portion, a pair of vertical wall portions continuous with both sides of the top plate portion in the width direction, and a pair of flange portions continuous with the vertical wall portions. In particular, the present invention relates to a method for manufacturing a press-formed product having asymmetric flange portions, which manufactures a press-formed product in which the shapes of the pair of flange portions are asymmetric. [Background technology]

[0002] As automobile crash safety standards become stricter, vehicle crash safety is being improved, but carbon dioxide emission regulations also require vehicle weight reduction to improve fuel efficiency and promote the shift to electric vehicles. In order to achieve both improved crash safety and weight reduction, the use of high-strength steel sheets (also known as high-tensile steel) of 590 MPa class or higher is becoming increasingly common in vehicle body structural parts. High-tensile steel has high strength, which causes large residual stress after press forming, so springback after demolding has been an issue. In particular, in the case of long press-formed products, twisting springback is likely to occur, causing the shape of the press-formed product to deviate from the target shape after demolding, which has been a problem.

[0003] Automotive parts that are subject to torsional springback include, for example, parts with a hat cross section that include a top plate portion, a pair of vertical wall portions that are continuous with the top plate portion, and a pair of flange portions that are continuous with the vertical wall portions, such as bumper parts. In such long parts with a hat cross section, if the shape of the pair of flange portions is asymmetric, for example, if the shape or arrangement of the bead-shaped portions provided on the flange portions is asymmetric, torsional springback is likely to occur in the press-molded product after release from the mold.

[0004] Therefore, a conventional method has been disclosed in Patent Document 1, in which an excess bead is added to the flange portion of the target shape to level out the residual stress in the press-molded product, thereby suppressing twisting after release from the mold. Furthermore, as in Patent Document 2, a method is disclosed in which a fillet is formed on the punch shoulder or the die shoulder to relieve the tensile stress during press molding, thereby suppressing twisting after release from the mold. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-255117 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-202189 Summary of the Invention [Problem to be solved by the invention]

[0006] However, press-molded products formed by the press-molding method of Patent Document 1 have beads formed on the flanges to prevent twisting, and therefore have shapes that differ from the original target shapes. Furthermore, the formation of the beads makes the shape of the flanges asymmetrical in the width direction of the press-molded product, which creates the problem of new twisting occurring easily.

[0007] Furthermore, press-formed products formed by the press-forming method described in Patent Document 2 also have fillets on the punch shoulder and die shoulder, and therefore differ from the original target shape. Furthermore, after such press-formed products are incorporated into a vehicle body, if compressive stress is applied to the press-formed product due to a collision of the vehicle body or the like, the press-formed product becomes prone to bending starting from the fillets, resulting in problems with rigidity and crashworthiness.

[0008] The present invention has been made to solve such problems, and provides a method for manufacturing a press-molded product having asymmetric flange portions that can prevent twisting of a press-molded product having a pair of asymmetric flange portions after release from the mold without changing the shape from the original target shape. [Means for solving the problem]

[0009] (1) The manufacturing method of the present invention for a press-formed product having an asymmetric flange portion is a method for manufacturing a press-formed product having a hat cross-sectional shape with a top plate portion, a pair of vertical wall portions continuing on both sides of the top plate portion in the width direction, and a pair of flange portions continuing on the vertical wall portions, and in which the shape of the pair of flange portions is asymmetric, as a target shape, and is characterized by comprising: a blank manufacturing process for manufacturing a blank having at least a flange equivalent portion that is wider than the flange equivalent portion of an expanded blank obtained by expanding the target shape; a press-forming process for press-forming an intermediate product having a hat cross-sectional shape in which the top plate portion and vertical wall portions are the same as the target shape and the flange portions are wider than the target shape, using the manufactured blank; and a trimming process for trimming the wide flange portions of the intermediate product to obtain the target shape.

[0010] (2) Furthermore, the manufacturing method of the press-formed product having an asymmetric flange portion according to the present invention is a method for manufacturing a press-formed product having a hat cross-sectional shape with a top plate portion, a pair of vertical wall portions continuing on both sides of the top plate portion in the width direction, and a pair of flange portions continuing on the vertical wall portions, wherein the shape or arrangement of the bead-shaped portions formed in the pair of flange portions is asymmetric, as a target shape, and is characterized by comprising: a blank manufacturing process for manufacturing a blank having, at least in part, a flange-equivalent portion that is wider than the flange-equivalent portion of an expanded blank obtained by expanding the target shape, such that the wider flange-equivalent portion includes a portion corresponding to the bead-shaped portion whose shape or arrangement is asymmetric; a press-forming process for press-forming an intermediate product having a hat cross-sectional shape in which the top plate portion and vertical wall portions are the same as the target shape, the flange portions are wider than the target shape, and the bead-shaped portions are formed in the flange portions; and a trimming process for trimming the wide flange portions of the intermediate product to obtain the target shape.

[0011] (3) In addition, in the above (1) or (2), the blank is made of a steel plate having a tensile strength of 590 MPa or more. [Effects of the Invention]

[0012] The present invention can prevent twisting after release from the mold without changing the original target shape in the production of a press-molded product in which the shapes of a pair of flange portions are asymmetric. As a result, even when high-tensile steel is used, press-formed products with stable and good shapes can be obtained, reducing the need for shape correction of press-formed products after press-forming and die modification during press-forming, which can greatly contribute to improving the production efficiency and yield of press-formed products. [Brief explanation of the drawings]

[0013] [Figure 1] 1A to 1C are explanatory diagrams illustrating a method for manufacturing a press-formed product having an asymmetric flange portion according to an embodiment of the present invention. [Figure 2] 2A, 2B, and 2C are diagrams showing a target shape in an embodiment, in which FIG. 2A is a perspective view, FIG. 2B is a top view, and FIG. 2C is a side view. [Figure 3] FIG. 3(a) is a diagram showing the longitudinal stress of an intermediate product after the press-forming process, and FIG. 3(b) is a diagram showing the longitudinal stress of a press-formed product after the trimming process. [Figure 4] 10A and 10B are diagrams illustrating displacement of a press-molded product in the press-molding direction after demolding in an embodiment. [Figure 5] FIG. 1 is a diagram showing a conventional blank shape. [Figure 6] FIG. 10 is a diagram showing displacement in the press-molding direction of a press-molded product after demolding in a conventional example. [Figure 7] FIG. 10 is a diagram showing longitudinal stress of a press-formed product in a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0014] A method for manufacturing a press-formed product having an asymmetric flange portion according to this embodiment will be described using the target shape shown in FIG. 2 as an example. The press-molded product 1 shown in Figure 2 has a hat-shaped cross-section and includes a top plate portion 3, a pair of vertical wall portions 5 continuing on both sides of the top plate portion 3 in the width direction, and a pair of flange portions 7 continuing from the vertical wall portions 5.

[0015] As shown in FIG. 2(b), a pair of flange portions 7 of the press-formed product 1 are formed with bead-shaped portions 9 that are arranged asymmetrically in the width direction, and the shapes of the pair of flange portions 7 are asymmetric. When the press-formed product 1 having the hat-shaped cross section shown in Fig. 2 is manufactured by a conventional method, it is prone to spring back and twist when released from the mold after press-forming. This point will be explained below.

[0016] The shape of a blank used in a conventional method is shown in Figure 5. Blank 19 shown in Figure 5 is produced by punching out a blank of the same shape as the expanded blank obtained by expanding press-molded product 1 in Figure 2 from a metal plate. Since the conventional blank 19 has a shape obtained by expanding the target shape, as shown in Figure 5, the shape of a pair of flange equivalent portions 19a corresponding to the pair of flange portions 7 of the press-formed product 1 is asymmetrical left and right in the width direction.

[0017] FIG. 6 shows the results of an FEM analysis when such a blank 19 is formed into a target shape. Figure 6 shows a top view of the shape of the press-formed product 1 after a blank 19 made of 1180 MPa grade material is press-formed into a target shape and released from the mold. Here, the longitudinal direction of the press-formed product 1 is the X direction, the width direction is the Y direction, and the press forming direction is the Z direction.

[0018] Displacement in the press-molding direction (Z direction) is shown by shading in the figure. Here, displacement in the press-molding direction (Z direction) refers to the degree to which each part of the press-molded product 1 is displaced toward the front of the page relative to the target shape when the center of the top plate in the longitudinal direction is used as a fixed point and the press-molded product 1 after release is compared with the target shape, and the magnitude of the displacement is shown by shading. The figure also shows numerical values ​​for the displacement at the four corners of the press-formed product 1. If the displacement in the Z direction differs significantly between the left and right in the width direction, this indicates that twisting has occurred in that area. Below, the shape characteristics and twists occurring at each end of the press-formed product 1 will be described, dividing it into the left half of the page and the right half of the page from the center in the longitudinal direction (see dashed line).

[0019] First, in the region from the longitudinal center (dashed line) of the press-formed product 1 to the left half of the page, the arrangement of the bead-shaped portions 9 formed on the pair of flange portions 7 is symmetrical. The Z-directional displacement of the upper left corner of the page is 12.6 mm, and the Z-directional displacement of the lower left corner of the page is 12.3 mm, so the Z-directional displacements of the two corners are almost the same. Therefore, it can be seen that there is almost no twisting at the end of the press-formed product 1 on the left side of the page.

[0020] On the other hand, in the region from the longitudinal center (dashed line) of the press-formed product 1 to the right half of the page, the arrangement of the bead-shaped portions 9 formed on the pair of flange portions is asymmetrical in the width direction. The Z-direction displacement of the upper right corner of the page is 9.6 mm, and the Z-direction displacement of the lower right corner of the page is 13.9 mm, a difference of 4.3 mm. Therefore, it can be seen that a twist of 4.3 mm has occurred at the end of the press-formed product 1 on the right side of the page.

[0021] The reason why the above-mentioned twist occurs will be explained with reference to FIG. Fig. 7 shows the stress at the bottom dead center when the blank 19 in Fig. 5 is press-formed. The stress shown in Fig. 7 is compressive stress in the longitudinal direction (X direction) and is the average in the plate thickness direction.

[0022] Comparing the area surrounded by the dashed line in Figure 7 (the area where the bead-shaped portion 9 is arranged asymmetrically in the width direction), it is clear that the stress distribution is asymmetric. As such, the stress distribution in the flange portion 7 differs between the left and right in the width direction at the bottom dead center of forming, which causes twisting in the press-molded product 1 after release from the mold.

[0023] As a result of intensive research, the inventors have found that when a blank having a wide excess pad on the outside of the flange-equivalent portion of a conventional blank shape is used to press-form an intermediate product, the stress distribution spreads toward the left and right ends of the flange in the width direction. Furthermore, they have found that trimming the wide excess pad from the intermediate product can remove the areas with different stress distributions on the left and right sides in the width direction, thereby suppressing the above-mentioned twisting. The method for manufacturing a press-formed product having an asymmetric flange according to this embodiment is based on this finding. In addition, the press-formed products that are prone to twisting and that are the subject of the present invention include, in addition to curved parts when viewed from the side as shown in Figure 2, parts that are curved when viewed from above, and parts that have flange portions with different uneven shapes on the left and right.

[0024] This embodiment is a method for manufacturing a press-formed product 1 having a pair of flange portions 7 with asymmetrically formed bead-shaped portions 9 as shown in Figure 2 as a target shape, and includes a blank preparation process, a press forming process, and a trimming process. Each step will be described in detail below.

[0025] <Blank manufacturing process> The blank preparation step is a step of preparing a blank 11 as shown in FIG. 1(a) by punching out a metal plate or the like. The blank 11 of this embodiment has a shape in which an excess pad portion is provided on the outside of a flange-equivalent portion (corresponding to the flange-equivalent portion 19a of the conventional blank 19) in a developed shape obtained by developing a target shape. Therefore, the blank 11 has a flange-equivalent portion 11a that is wider than the flange-equivalent portion 19a of the conventional blank 19 (see FIG. 5).

[0026] FIG. 1(a) shows the blank shape when the pair of flange-equivalent portions 11a of the blank 11 are each widened by 20 mm, and the blank shape when the pair of flange-equivalent portions 11a are each widened by 40 mm. The flange-equivalent portion 11a of the blank 11 does not need to be wide over its entire length. As shown in Figure 1(a), it is sufficient that the portion including the area where the widthwise asymmetric bead-shaped portion 9 of the flange portion 7 of the target shape is formed is wide.

[0027] Furthermore, in the blank 11 of Figure 1(a), the flange equivalent portion 11a has the same width expansion amount and the shape of the flange equivalent portion 11a on the left and right in the width direction is approximately symmetrical, but the present invention is not limited to this, and the shape of the flange equivalent portion 11a may be asymmetric. However, it is preferable to make the widths of the pair of flange-equivalent portions 11a the same, since this makes it less likely that uneven stress will occur in the top plate portion 3 and the vertical wall portion 5 when press-molding the intermediate product 13, which will be described later.

[0028] <Press molding process> The press forming process is a process in which the blank 11 produced in the blank production process is used to press-form an intermediate product 13 as shown in Fig. 1(b). Note that Fig. 1(b) shows an example in which a blank 11 having a flange-equivalent portion 11a that is 40 mm wider is used.

[0029] The intermediate product 13 has a top plate portion 3 and a vertical wall portion 5 that are the same as the target shape (see FIG. 2), a flange portion 15 that has a hat-shaped cross section that is wider than the flange portion 7 of the target shape, and a bead-shaped portion 17 that corresponds to the bead-shaped portion 9 of the target shape is formed in the flange portion 15. In FIG. 1(b), parts that have the same shape as the target shape are given the same reference numerals.

[0030] <Trimming process> As shown in Fig. 1(c), the trimming process is a process of trimming the wide flange portion 15 of the intermediate product 13. Specifically, the target shape (press-formed product 1) is obtained by removing the excess material described in the blank preparation process.

[0031] Figure 3 shows the results of FEM analysis of the stress distribution in the intermediate product 13 at the bottom dead center after the press forming process and the residual stress distribution in the press-formed product 1 after the trimming process. The stress shown in Figure 3 is compressive stress in the longitudinal direction (X direction), as in Figure 7, and is the average in the plate thickness direction.

[0032] Figure 3(a) shows the stress distribution at the bottom dead center when the intermediate product 13 is press-formed in the press forming process. As shown in Figure 3(a), the compressive stress generated in the wide flange portion 15 is concentrated on the right side of the page and near the widthwise end of the flange portion 15. Furthermore, when comparing a pair of flange portions 15, the stress distribution is not symmetrical.

[0033] Figure 3(b) shows the residual stress distribution in the press-formed product 1 after trimming the intermediate product 13 in Figure 3(a). As shown in Figure 3(b), when the flange portion 15 of the intermediate product 13 is trimmed to the target shape, the area where compressive stress was concentrated is removed, and the compressive residual stress generated in the flange portion 7 of the press-formed product 1 is reduced. Furthermore, the residual stress distribution is almost symmetrical.

[0034] FIG. 4 shows the displacement in the press-molding direction (Z direction) of the press-molded product 1 manufactured in this embodiment. As in Figure 6, Figure 4 compares the press-molded product 1 after release from the mold with the target shape, with the center of the longitudinal direction used as a fixed point, and shows by shades how much each part of the press-molded product 1 has displaced toward the front of the page relative to the target shape. As with the conventional example in FIG. 6, the press-formed product 1 is divided from the center in the longitudinal direction (see the broken line) into the left half and the right half of the paper, and the magnitude of twist occurring at each end will be described.

[0035] In the region of the press-formed product 1 from the longitudinal center (dashed line) to the left half of the page, the Z-direction displacement of the upper left corner of the page was 10.6 mm, and the Z-direction displacement of the lower left corner of the page was 11.6 mm, and the Z-direction displacements of the two corners were almost the same. Therefore, almost no twisting occurred at the end on the left side of the page of the press-formed product 1 manufactured in this embodiment, as in the conventional example.

[0036] Furthermore, in the area from the longitudinal center (dashed line) of the press-formed product 1 to the right half of the page, the Z-direction displacement of the upper right corner of the page was 16.4 mm, and the Z-direction displacement of the lower right corner of the page was 16.3 mm, meaning that the Z-direction displacements of the two corners were almost the same. Therefore, even in the right-hand edge of the press-formed product 1 on the page, where a twist of 4.3 mm occurred in the conventional example (Fig. 6), it can be seen that twist was significantly reduced, springback was suppressed, and the shape was improved.

[0037] As described above, according to this embodiment, when producing a press-molded product 1 in which the shape of the pair of flange portions 7 is asymmetric in the width direction, it is possible to reduce twisting that occurs at the longitudinal ends after release from the mold.

[0038] The press-formed product 1 having the target shape in the above embodiment has a pair of flange portions 7 with bead-shaped portions 9 of the same shape arranged asymmetrically in the width direction, so that the shape of the flange portions 7 is asymmetric in the width direction, but the shape of the press-formed product targeted by the present invention is not limited to this. For example, the shape of the bead-shaped portion 9 formed on one flange portion 7 of the press-molded product may be different from the shape of the bead-shaped portion 9 formed on the other flange portion 7. Even when the shapes of the bead-shaped portions 9 are different, the shapes of the pair of flange portions 7 become asymmetrical in the width direction, making the press-molded product more susceptible to twisting, and therefore the present invention is effective.

[0039] Furthermore, the present invention is effective when manufacturing a press-molded product as a target shape, which has a hat cross-sectional shape with a top plate portion, a pair of vertical wall portions, and a pair of flange portions, regardless of whether or not there is a bead-shaped portion, and in which the shape of the pair of flange portions is asymmetrical in the width direction.

[0040] As described above, in this embodiment, the intermediate product 13 having the wide flange portion 15 is press-formed, and the flange portion 15 is trimmed to obtain the target shape. During this trimming, the balance of stress changes, and the stress (tensile stress) in the top plate portion 3 becomes relatively large, which may cause upward warping.

[0041] In the case of the press-formed product 1 of this embodiment shown in Fig. 4, the difference between the Z-direction displacement of the upper left corner of the page and the Z-direction displacement of the upper right corner of the page was 5.8 mm. Also, the difference between the Z-direction displacement of the lower left corner of the page and the Z-direction displacement of the lower right corner of the page was 4.7 mm. On the other hand, in the case of the conventional example in Figure 6, the difference between the Z direction displacement of the upper left corner of the paper and the Z direction displacement of the upper right corner of the paper was 3.0 mm, and the difference between the Z direction displacement of the lower left corner of the paper and the Z direction displacement of the lower right corner of the paper was 1.6 mm.

[0042] As described above, in the press-formed product 1 of this embodiment shown in FIG. 4, the difference in Z direction displacement between the end on the left side of the page and the end on the right side of the page is larger than in the conventional example. In order to suppress such upward warping due to stress (tensile stress) in the top plate portion 3, for example, it is advisable to perform press molding using a mold in which the radius of curvature of the top plate portion 3 is made smaller than the target shape. [Example]

[0043] The effect of preventing twisting of the press-formed product according to the present invention has been confirmed, and will be explained below. In this example, the press-formed product 1 shown in FIG. 2 was used as a target shape, and a press-formed product having flange portions asymmetrical in the width direction as described in the embodiment was manufactured. For the blanks of this example, three types of steel plates (all 1.8 mm thick) with tensile strengths of 590 MPa, 980 MPa, and 1180 MPa were used.

[0044] In the conventional example, an expanded blank (see FIG. 5) having a target shape is press-formed to produce a press-formed product having the target shape. In the examples of the invention, blanks having flanges wider than those of the conventional blanks were prepared, and the blanks were press-formed into intermediate products. The flanges of the intermediate products were then trimmed to produce press-formed products of the target shape. The examples of the invention were carried out with the flanges of the blanks widened by 20 mm and 40 mm. Table 1 shows the amount of twist in the press-formed products in the above conventional example and inventive example.

[0045] [Table 1]

[0046] The amount of twist shown in Table 1 indicates the amount of twist at the right end of the press-formed product. Specifically, it is the amount of twist at the end on the right side of the paper in press-formed product 1 in Figure 4 or Figure 6, and is the value obtained by calculating the difference between the Z-direction displacement of the upper right corner of the paper and the Z-direction displacement of the lower right corner of the paper. As explained in the embodiment, the Z-direction displacement is the displacement in the press-molding direction when the press-molded product after demolding is compared with the target shape, with the longitudinal center of the top plate portion used as a fixed point.

[0047] No. 1 to No. 3 are examples in which 590 MPa grade material was used for the blank. No. 1, a conventional example, was produced by press-forming an expanded blank into the target shape, and the amount of twist was 1.7 mm.

[0048] In contrast, in Example No. 2, an invention example, the flange-equivalent portions of the blank were made 20 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product manufactured using this blank was 0.6 mm. Example No. 2 showed a lower amount of twist than Example No. 1, and was therefore favorable. In addition, in Example No. 3, an invention example, the flange-equivalent portions of the blank were made 40 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product manufactured using this blank was 0.4 mm. Example No. 3, which had a larger width expansion than Example No. 2, showed even less twist and was even better.

[0049] No. 4 to No. 6 are examples in which 980 MPa grade material was used for the blank. No. 4, a conventional example, was produced by press-forming an expanded blank into the target shape, and the amount of twist was 3.2 mm.

[0050] In contrast, in Example No. 5, an invention example, the flange-equivalent portions of the blank were made 20 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product manufactured using this blank was 0.4 mm. Example No. 5 had a lower amount of twist than Example No. 4, and was therefore better. In addition, in Example No. 6, an invention example, the flange-equivalent portions of the blank were made 40 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product manufactured using this blank was 0.3 mm. Example No. 6, which had a larger width expansion than Example No. 5, showed even less twist and was even better.

[0051] No. 7 to No. 9 are examples in which 1180 MPa grade material was used for the blank. No. 7, a conventional example, was made by press-forming an expanded blank into the target shape, and the amount of twist was 4.3 mm.

[0052] In contrast, in Example No. 8, an invention example, the flange-equivalent portions of the blank were made 20 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product manufactured using this blank was 0.5 mm. No. 8 had a lower amount of twist than No. 7, making it a better product. In addition, in Example No. 9, an invention example, the flange-equivalent portions of the blank were made 40 mm wider on each side than the flange-equivalent portions of the expanded blank developed to the target shape, and the amount of twist in the press-formed product produced using this blank was 0.1 mm. Example No. 9, which had a larger width expansion than Example No. 8, showed even less twist and was even better.

[0053] As shown in the above examples, the present invention can obtain a sufficient twist suppression effect even when a steel sheet having a tensile strength of 590 MPa or more is used for the blank.

[0054] From the above, it has been confirmed that the method of the present invention is effective in preventing twisting of press-formed products due to springback after press-forming. [Explanation of symbols]

[0055] 1 Press-molded products 3 Top plate 5 Vertical wall section 7 Flange 9 Bead shape part 11 Blank 11a Flange equivalent part 13 Intermediate products 15 Flange 17 Bead shape part 19 Blank (conventional example) 19a Flange equivalent part

Claims

1. A method for manufacturing a press-formed product having asymmetric flange portions, the method comprising: manufacturing a press-formed product having a hat-shaped cross section including a top plate portion, a pair of vertical wall portions continuous with both sides of the top plate portion in a width direction, and a pair of flange portions continuous with the vertical wall portions, the press-formed product having asymmetric shapes or arrangements of bead-shaped portions formed on the pair of flange portions as a target shape; a blank manufacturing process for manufacturing a blank having at least a flange equivalent portion wider than the flange equivalent portion of the expanded blank obtained by expanding the target shape, such that the wider flange equivalent portion includes a portion corresponding to the bead shape portion, which is asymmetric in shape or arrangement; a press-molding process in which the produced blank is used to press-molde an intermediate product having a hat cross-sectional shape, in which a top plate portion and a vertical wall portion are the same as the target shape, a flange portion is wider than the target shape, and a bead-shaped portion is formed in the flange portion; a trimming step of trimming the wide flange portion of the intermediate product to form the target shape, A method for manufacturing a press-formed product having an asymmetric flange portion, characterized in that in the blank manufacturing process, the width of the wide flange equivalent portion is made the same on both sides.

2. 2. The method for manufacturing a press-formed product having an asymmetric flange portion according to claim 1, wherein the length of the bead-shaped portion is shortened in the trimming step.

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