Manufacturing method for press-formed products

Abstract

To suppress cracking of an elongated flange molding part at a longitudinal wall tip or a flange tip and to suppress buckling easily occurring in a ridgeline part where a top plate valley line is connected to a longitudinal wall in manufacturing of a press-molded product having the top plate valley line formed in a top plate and including first and second top plates holding the top plate valley line between them.SOLUTION: A method for manufacturing a press-molded product 1 comprises: a first molding step of press-molding an intermediate molded product 17 having a step forming part 23 composed of a step including an intermediate top plate valley line 19c, first and second intermediate top plates 19a and 19b provided sandwiching the intermediate top plate valley line 19c, an intermediate ridgeline 21 formed in a part corresponding to a ridgeline 5, an intermediate longitudinal wall 20 connected to the intermediate ridgeline 21, and an intermediate step valley 22 connected to the intermediate longitudinal wall, and an outer surface part 25 connected to the step forming part 23 and extending outward; and a second molding step of press-molding the intermediate molded product 17 into the press-molded product 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] A method for manufacturing a press-formed product having a top plate portion and a vertical wall portion continuous from the top plate portion via a ridge line portion, wherein a top plate valley line intersecting the ridge line portion is formed on the top plate portion, and the first top plate portion and the second top plate portion are provided with the top plate valley line interposed therebetween.

Background Art

[0002] With the tightening of automotive collision safety standards, while the collision safety of the vehicle body is improving, due to carbon dioxide emission regulations, weight reduction of the vehicle body is also required for improving fuel efficiency and promoting electrification. In order to achieve both improvement of the collision safety and weight reduction of the vehicle body, the application of high-strength steel sheets of 590 MPa or higher (also referred to as high-tensile materials) to vehicle body structural parts is progressing.

[0003] Automotive parts include, for example, the press-formed product 1 shown in FIG. 5. The press-formed product 1 has a top plate portion 3 and a vertical wall portion 7 continuous from the top plate portion 3 via a ridge line portion 5. A top plate valley line 3c is formed on the top plate portion 3, and the first top plate portion 3a and the second top plate portion 3b are provided with the top plate valley line 3c interposed therebetween. When such a press-formed product 1 is press-formed, elongation flange deformation is applied to (the tip of the vertical wall portion 7 or the tip of the flange portion) located on the extension of the top plate valley line 3c, and cracks are likely to occur. In addition, buckling (wrinkling, folding) is likely to occur at the portion of the ridge line portion 5 where the top plate valley line 3c connects to the vertical wall portion 7. Especially in the case of high-tensile materials, due to the increase in strength, cracks at the elongation flange forming portion at the tip and buckling (wrinkling, folding) of the ridge line portion 5 are likely to occur, which is a problem.

[0004] In this regard, conventionally, countermeasures against cracks associated with elongation flange deformation of a press-formed product having a top plate portion that is flat and has a concave outer peripheral edge in a top view and a vertical wall portion continuous from the top plate portion along the concave outer peripheral edge have been proposed, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] International Publication No. 2014 / 097745 [Overview of the project] [Problems that the invention aims to solve]

[0006] The press forming method described in Patent Document 1 above is for press-formed products in which the top plate portion is flat and the outer edge of the top plate portion is concave when viewed from above. On the other hand, the press-formed product targeted by the present invention is a press-formed product having a top plate valley line formed on the top plate portion, and comprising a first top plate portion and a second top plate portion sandwiching the top plate valley line. Thus, the press-formed product covered by Patent Document 1 and the press-formed product covered by the present invention have different shapes.

[0007] Therefore, even if the press forming method described in Patent Document 1 is applied to the press-formed product targeted by the present invention, it is not possible to prevent cracking at the tip located on the extension of the top plate valley line, or buckling (wrinkling, folding) at the ridge line portion where the top plate valley line connects to the vertical wall portion.

[0008] The present invention was made to solve the above problems, and aims to suppress cracking of the stretch flange forming portion at the tip of the vertical wall portion and the tip of the flange portion, and to suppress buckling (wrinkling, folding) that tends to occur in the portion of the ridge where the top plate valley connects to the vertical wall portion, when manufacturing a press-formed product having a vertical wall portion that is continuous from the top plate portion via a ridge portion, a top plate valley line formed in the top plate portion, and a first top plate portion and a second top plate portion sandwiched between the top plate valley line. [Means for solving the problem]

[0009] (1) A method for manufacturing a press-formed product according to the present invention, comprising a top plate portion and a vertical wall portion continuous with the top plate portion via a ridge portion, wherein the top plate portion has a top plate valley line that intersects the ridge portion, and the top plate portion comprises a first top plate portion and a second top plate portion on either side of the top plate valley line, A first molding step for press molding an intermediate molded product having an intermediate top plate valley line, a first intermediate top plate portion and a second intermediate top plate portion provided on either side of the intermediate top plate valley line, an intermediate ridge portion formed in the portion corresponding to the ridge line portion, an intermediate vertical wall portion continuous with the intermediate ridge line portion, a step-shaped portion consisting of a step including an intermediate step valley portion continuous with the intermediate vertical wall portion, and an outer surface portion extending outward in connection with the step-shaped portion, The present invention is characterized by comprising a second molding step of press-forming the aforementioned intermediate molded product into the aforementioned press-molded product.

[0010] (2) Furthermore, in the present invention described in (1) above, the press-formed product manufactured by press forming is characterized in that it has the top plate portion, the vertical wall portion which is continuous with the top plate portion via the ridge portion, and the flange portion which is continuous with the vertical wall portion.

[0011] (3) Furthermore, in the case described in (1) or (2) above, the radius of curvature of the intermediate ridge portion of the intermediate molded product is the same as or greater than the radius of curvature of the ridge portion of the press-formed product. [Effects of the Invention]

[0012] According to the present invention, cracks caused by stretch flange deformation at the tip of the vertical wall portion or the tip of the flange portion located on the extension of the top plate valley line can be suppressed, and buckling (wrinkling, folding) that tends to occur at the ridge portion where the top plate valley line connects to the vertical wall portion can be suppressed. [Brief explanation of the drawing]

[0013] [Figure 1] This is an explanatory diagram of the method for manufacturing a press-formed product according to this embodiment. [Figure 2] This is an explanatory diagram of the intermediate molded product formed in this embodiment. [Figure 3] This is an explanatory diagram of the molding process in the second molding step in this embodiment. [Figure 4] This is an explanatory diagram of the effects and actions in this embodiment. [Figure 5]It is an explanatory drawing of the press-formed product targeted by the present invention. [Figure 6] It is an explanatory drawing of a conventional method for manufacturing a press-formed product. [Figure 7] It is an explanatory drawing of the forming process of a conventional press-forming method. [Figure 8] It is an explanatory drawing of the problems of a press-formed product manufactured by a conventional press-forming method. [Figure 9] It is an explanatory drawing of a press-formed product and an intermediate-formed product according to another aspect of the present invention. [Figure 10] It is an explanatory drawing of the press-formed product targeted for manufacture in the example. [Figure 11] It is an explanatory drawing of the press-forming method of the conventional example in the example. [Figure 12] It is an explanatory drawing of the press-forming analysis result of the conventional example in the example. [Figure 13] It is an explanatory drawing of the press-forming method of the inventive example in the example. [Figure 14] It is an explanatory drawing of the press-forming analysis result of the inventive example in the example.

Mode for Carrying Out the Invention

[0014] Regarding the press-formed product having the target shape targeted by the present invention, an explanation will be given based on the example of the L-shaped cross-sectional shape in FIG. 5. The press-formed product 1 targeted by the present invention has at least a top plate portion 3 and a vertical wall portion 7 that is continuous from the top plate portion 3 via a ridge line portion 5. A top plate valley line 3c that intersects the ridge line portion 5 is formed in the top plate portion 3, and a first top plate portion 3a and a second top plate portion 3b are provided with the top plate valley line 3c interposed therebetween.

[0015] <0​​​​Conventionally, a punch 9 having a top plate valley line forming section 9b, a pad 11, and a die 13 were used to form a top plate valley line 3c on the top plate section 3 by pressing the blank 15, which is a metal plate, with the pad 11 and the punch 9, while the die 13 was moved relative to form the vertical wall section 7. The die 13 also has a die jaw portion 13b for forming the ridge portion 5.

[0016] Figure 7 shows a cross-section of the top plate valley line 3c (cross-section AA in Figure 5) during press forming. The values ​​such as [3mm up] in Figure 7 represent the gap between the punch shoulder 9a of the punch 9 and the die jaw 13b in the press forming direction, taking into account the sheet thickness up to the bottom dead center of the forming process. For example, when [3mm up] is indicated, the gap between the punch shoulder 9a of the punch 9 and the die jaw 13b is the sheet thickness of the press-formed product 1 + 3mm.

[0017] As shown in Figure 7, the blank 15 is pressed against the top plate valley line forming section 9b of the punch 9 by the pad 11 at a height of [37 mm up], and the top plate valley line 3c and the first top plate section 3a and the second top plate section 3b are formed on the blank 15 on both sides (front and back of the paper). At [27mm up], the die 13 comes into contact with the blank 15, which is an extension of the top plate valley line 3c. However, the top plate valley line 3c has high rigidity because two top plate surfaces are formed on both sides of it. As a result, as press forming progresses, at [25mm up], the blank 15 that has come into contact with the die 13 does not follow the punch shoulder portion 9a and collapses without making contact. Furthermore, the blank 15 that bends at [21mm up] bends in the forming direction without contacting the punch 9, and the blank 15 that bends at [14mm up] and [3mm up] is formed into the vertical wall portion 7 in the gap between the die 13 and the punch 9. Then, at a [1mm up] position, it contacts the punch shoulder portion 9a, forming the ridge portion 5 that connects from the top plate valley line 3c to the vertical wall portion 7, and reaching the bottom dead center of the forming process.

[0018] Figure 8 shows the plate thickness distribution at the bottom dead center of the forming process, obtained by FEM analysis of a conventional press forming process. In Figure 8, the dotted line AA indicates the position of the top plate valley line 3c, similar to Figure 5. As shown in Figure 8, the tip of the vertical wall section 7 located on the extension of the top plate valley line 3c undergoes elongation flange deformation, resulting in a significant reduction in plate thickness with a maximum thickness reduction rate of 21.5%, making it prone to cracking. Furthermore, the plate thickness at the ridge section 5 connecting the top plate valley line 3c to the vertical wall section 7 increases significantly with a maximum thickness increase rate of 42.9%, leading to wrinkles and eventually folds.

[0019] As described above, in the conventional press forming process, two top surfaces are formed by the punch 9 and pad 11 at the beginning of forming, and the top surface valley line 3c and its vicinity, sandwiched between these two top surfaces, have high rigidity in the bending direction due to the formation of the top surface valley line 3c. Therefore, when the extension of the highly rigid top surface valley line 3c and its vicinity are formed by the die 13, the top surface valley line 3c does not follow the punch shoulder 9a and does not come into contact with it, causing a crease near the ridge line 5 that connects to the vertical wall 7, increasing the plate thickness and making it prone to wrinkles and folds. Furthermore, because the two top surfaces are formed in a roughly V-shape, when attempting to form the tip of the blank 15 into the vertical wall portion 7, it is bent in a direction that spreads apart from each other. As a result, elongation flange deformation is applied to the tip of the vertical wall portion 7 located on the extension of the top surface valley line 3c, and a large tension acts on it, reducing the plate thickness and making it prone to cracking.

[0020] In order to suppress increases and decreases in plate thickness during this series of molding processes, the inventors focused on the deformation of the blank 15 from [25mm up] to [21mm up] in Figure 7. Furthermore, we discovered that the problem lies in the fact that the bending that occurs at [25mm up] is formed without contacting the punch shoulder portion 9a.

[0021] Therefore, we considered forming an intermediate molded product (Figure 2) in advance, which is bent along the radius (R) of the ridge line 5 connecting the top plate section 3 to the vertical wall section 7, and then press-forming the intermediate molded product into the target shape. We thought that this would suppress the bending of the intermediate molded product into the target shape, as the intermediate ridge line 21 would come into contact with the punch shoulder section 9a from the beginning of the press-forming process, preventing further deformation.

[0022] Furthermore, regarding the above-mentioned intermediate molded product, in addition to the intermediate top plate portion 19, intermediate ridge portion 21, and intermediate vertical wall portion 20 shown in Figure 2, we considered providing an outer surface portion 25 extending outward from the intermediate stepped valley portion 22 to create a stepped shape. As a result, in the process of press-forming the intermediate molded product into the target shape, the height of the stepped intermediate vertical wall portion 20 is formed first, so when the outer surface portion 25 is press-formed to the vertical wall portion 7, the amount of elongation flange deformation of the outer surface portion 25 extending from the intermediate vertical wall portion 20 is reduced, making it less likely for cracks to occur.

[0023] The present invention is based on this idea, and as shown in Figure 1, the press molding process is divided into two steps: a first molding step for molding an intermediate molded product 17, and a second molding step for molding the intermediate molded product 17 into a press molded product 1 which is the target shape. As shown in Figure 2, the intermediate molded product 17 has an intermediate top plate portion 19, which consists of a first intermediate top plate portion 19a and a second intermediate top plate portion 19b, which are provided on either side of the intermediate top plate valley line 19c. Furthermore, the intermediate molded product 17 has an intermediate ridge portion 21 formed in the area corresponding to the ridge portion 5, an intermediate vertical wall portion 20 continuous with the intermediate ridge portion 21, and a step-shaped portion 23 consisting of a step including an intermediate step valley portion 22 continuous with the intermediate vertical wall portion 20. In other words, in this specification, the stepped portion from the point where the intermediate top plate portion 19 and the intermediate ridge portion 21 connect to the intermediate ridge portion 21, the intermediate vertical wall portion 20, the intermediate stepped valley portion 22, and the point where the intermediate stepped valley portion 22 and the outer surface portion 25 connect is referred to as the step-shaped portion 23. Furthermore, the intermediate molded product 17 has an outer surface portion 25 that extends outward in a continuous manner with the step-shaped portion 23. The outer portion 25 is formed into the vertical wall portion 7 in the second molding process.

[0024] Figure 2 shows an example where the outer surface portion 25 is parallel to the first intermediate top plate portion 19a and the second intermediate top plate portion 19b, but it is not necessary for the first intermediate top plate portion 19a and the second intermediate top plate portion 19b to be parallel. Furthermore, since the first intermediate top plate portion 19a and the second intermediate top plate portion 19b only need to become the first top plate portion 3a and the second top plate portion 3b of the press-formed product 1 in the second molding process, they do not need to perfectly match the shape of the first top plate portion 3a and the second top plate portion 3b of the press-formed product 1, which is the target shape. The intermediate top plate valley line 19c is the portion that becomes the top plate valley line 3c of the press-formed product 1 in the second forming process. The intermediate top plate valley line 19c only needs to be aligned with the target shape of the top plate valley line 3c of the press-formed product 1 in the longitudinal direction (X direction in Figure 2), and does not need to perfectly match the shape of the top plate valley line 3c of the press-formed product 1. The first and second molding processes will be explained in detail below, using the case where the intermediate molded product 17 has the shape shown in Figure 2 as an example, based on Figure 1.

[0025] <1st molding process> In the first molding process, as shown in Figure 1(a), a step molding punch 27 and a step molding die 29 are used to press-form the blank 15 into an intermediate molded product 17. Furthermore, it is preferable that the radius of curvature of the intermediate ridge portion 21 of the intermediate molded product 17 is the same as or greater than the radius of curvature of the ridge portion 5 of the press-molded product 1. This is because it makes it easier for the intermediate ridge portion 21 to come into contact with the punch shoulder portion 9a of the punch 9 during the second molding process. There are no particular restrictions on the upper limit of the radius of curvature of the intermediate ridge portion 21, but if the radius of curvature is too large, the area in which the intermediate ridge portion 21 contacts the punch shoulder portion 9a of the punch 9 may become smaller in the second molding process. Therefore, it is preferable that the radius of curvature of the intermediate ridge portion 21 is 5 times or less the radius of curvature of the ridge portion 5 of the press-formed product 1.

[0026] <Second molding process> In the second molding process, as shown in Figure 1(b), a punch 9, pad 11, and die 13 are used to form the target shape, which is the press-formed product 1 (Figure 5). The mold shown in Figure 1(b) is the same as the one shown in Figure 6 as a conventional example. The intermediate molded product 17 is placed on the punch 9, pressed down with the pad 11, and the die 13 is moved relative to the punch 9, thereby forming the outer surface portion 25 into the vertical wall portion 7 and forming the press-molded product 1 which is the target shape.

[0027] Figure 3 shows the movement of the punch 9 and die 13 during the second molding process, as well as the deformation process of the intermediate molded product 17, for a cross-section cut in the direction of arrow BB shown in Figure 2. Note that the values ​​such as [3mm up] are the same as in the case of Figure 7 mentioned above.

[0028] As shown in Figure 3, in the second molding process, the intermediate molded product 17 is placed on the punch 9 and pressed down by the pad 11. When molding begins, the intermediate molded product 17 is pressed against the top plate valley line molding section 9b of the punch 9, as shown in the figure at [37mm up], and at [27mm up] the intermediate ridge line section 21 of the step-shaped section 23 comes into contact with the punch shoulder section 9a of the punch 9. In this way, the intermediate ridge portion 21 in the step-shaped portion 23 of the intermediate molded product 17 follows the punch shoulder portion 9a, thereby suppressing the amount of deformation of the intermediate ridge portion 21 during the subsequent molding process, preventing an increase in plate thickness and preventing buckling.

[0029] Subsequently, the die 13 bends back the intermediate stepped valley portion 22 of the intermediate molded product 17 from [24mm up] to [15mm up], forming the vertical wall portion 7 in the gap between the die 13 and the punch 9 at [3mm up], and at [1mm up] the die jaw portion 13b contacts the intermediate ridge portion 21 of the intermediate molded product 17, reaching the bottom dead center of molding. During this period, no bending occurs in the transition from [27mm up] to [1mm up] as shown in Figure 7, which illustrates a conventional example.

[0030] Furthermore, since the intermediate molded product 17 has a step-shaped portion 23 formed thereon, the molding height formed on the vertical wall portion 7 in the second molding process is the distance from the intermediate step valley portion 22 of the step-shaped portion 23 to the end of the outer surface portion 25. For this reason, it is shorter than the distance from the start of the radius of the ridge portion 5 of the top plate portion 3 to the tip of the blank 15, as in the conventional example, and the reduction in plate thickness due to expansion flange deformation is suppressed, preventing cracking.

[0031] The press forming process of this embodiment was analyzed using FEM, and the sheet thickness distribution at the bottom dead center of the forming process for the first and second forming processes is shown in Figure 4. Figure 4(a) shows the sheet thickness distribution at the bottom dead center of the forming process for the first forming process, and Figure 4(b) shows the sheet thickness distribution at the bottom dead center of the forming process for the second forming process. As shown in Figure 4(a), in the first molding process, the maximum plate thickness increase rate is 8.5% at the intermediate ridge section 21 where the intermediate top plate valley line 19c connects to the intermediate vertical wall section 20. Furthermore, as shown in Figure 4(b), in the second molding process, the maximum increase in plate thickness at the ridge portion 5 where the top plate valley line 3c connects to the vertical wall portion 7 is 28.1%, and the maximum decrease in plate thickness at the tip of the vertical wall portion 7 located on the extension of the top plate valley line 3c is 19.7%.

[0032] Comparing the present invention shown in Figure 4(b) with the conventional example shown in Figure 8, the maximum increase in plate thickness at the ridge line 5 where the top plate valley line 3c connects to the vertical wall section 7 was 42.9% in the conventional case, while it was reduced to 28.1% in the present invention, demonstrating that wrinkles and folds can be suppressed. Furthermore, the maximum decrease in plate thickness at the tip of the vertical wall section 7 located on the extension of the top plate valley line 3c was 21.5% in the conventional case, while it was reduced to 19.7% in the present invention, demonstrating that cracks associated with expansion flange deformation can be suppressed.

[0033] In the above description, the first top plate portion 3a and the second top plate portion 3b of the press-formed product 1, and the first intermediate top plate portion 19a and the second intermediate top plate portion 19b of the intermediate molded product 17 were curved, but as shown in Figure 9, they may also be flat surfaces. Furthermore, it is preferable that the outer surface portion 25 be concave in the same direction as the top plate portion 3. If the outer surface portion 25 is an intermediate-shaped component that is bent outward from the vertical wall portion 7 into a convex, mountain-shaped section, the height of the vertical walls at the bases on both sides of the convex mountain-shaped section becomes higher than the height of the vertical wall at the top of the convex mountain-shaped section. As a result, a large tension acts in the left-right direction at the base of the convex mountain-shaped section, which can easily cause cracks to form at the tip of the outer surface portion 25, which forms the top of the convex mountain-shaped section. Therefore, in the present invention, in the intermediate molding process, a stepped intermediate molded product 17 having an outer surface portion 25 that is concave in the same direction as the top plate portion 3 is molded, and the height of the vertical wall on the extension of the valley line 19c of the intermediate top plate and the height of the vertical wall from the left and right ends of the intermediate top plate portion 19 are brought closer together so that the intermediate top plate portion 19 is concave in the same direction as the top plate surface. As a result, large tension is not applied to the left and right near the tip of the outer surface portion 25, and stable press molding becomes possible. [Examples]

[0034] To confirm the effectiveness of the press-formed product manufacturing method of the present invention, a press-formed analysis was performed using FEM, which is described below. Using a 1.4 mm thick, 590 MPa class steel plate, a press-formed product 31 was analyzed as shown in Figure 10. The product has a top plate portion 3, a ridge portion 5, a vertical wall portion 7, and a flange portion 33, with the top plate portion 3 consisting of two top plate portions 3, a first top plate portion 3a and a second top plate portion 3b. The thickness distribution was determined by performing a press-formed analysis on this product. The dimensions of each part of the press-formed product 31 are as shown in Figure 10. In Figure 10, the same and corresponding parts as those in the press-formed product 1 shown in Figure 5 are denoted by the same reference numerals.

[0035] Furthermore, it has been found through actual press forming experiments that wrinkles occur at the ridge line 5 where the top plate valley line 3c connects to the vertical wall section 7 when the plate thickness increases by 30% or more, and folds occur when the increase is 35% or more. In addition, it has been found that cracks occur at the tip of the flange section 33 located on the extension of the top plate valley line 3c when the plate thickness decreases by more than 20%.

[0036] As a conventional example, as shown in Figure 11, a press forming process in which the top plate valley line 3c is formed by the punch 9 and pad 11 in one step while the die 13 is moved relatively to press form the target shape shown in Figure 10 was analyzed using FEM. The results of determining the plate thickness distribution at the bottom dead center of forming are shown in Figure 12. The maximum increase in plate thickness at the ridge section 5 where the top plate valley line 3c connects to the vertical wall section 7 was 39.9%, indicating that wrinkles and folds may occur. Furthermore, the maximum decrease in plate thickness at the tip of the flange section 33, located on the extension of the top plate valley line 3c, was 24.8%, indicating that cracks may occur.

[0037] As an example of the present invention, as shown in Figure 13, a press molding process consisting of two steps, a first molding step for molding an intermediate molded product 17 and a second molding step for molding the intermediate molded product 17 into a press-molded product 31 with a target shape, was analyzed using FEM. In the example shown in Figure 13, the outer surface portion 25 of the intermediate molded product 17 is made parallel to the first intermediate top plate portion 19a and the second intermediate top plate portion 19b. Figure 14 shows the thickness distribution at the bottom dead center of the intermediate molded product 17 and the press-formed product 31, which is the target shape. The maximum increase in plate thickness at the intermediate ridge section 21 where the intermediate top plate valley line 19c connects to the intermediate vertical wall section 20 in the intermediate molded product 17 was 6.8% (see Figure 14(a)). Furthermore, it was found that the maximum increase in plate thickness at the ridge portion 5 where the top plate valley line 3c connects to the vertical wall portion 7 in the press-formed product 31 was 25.3%, indicating that no wrinkles or folds occurred. In addition, it was found that the maximum decrease in plate thickness at the tip portion of the flange portion 33 located on the extension of the top plate valley line 3c was 15.7%, indicating that no cracks occurred (see Figure 14(b)).

[0038] As described above, compared to the conventional example, the present invention reduces the maximum plate thickness increase rate at the ridge line 5 where the top plate valley line 3c connects to the vertical wall section 7, thereby suppressing wrinkles and folds. Furthermore, compared to conventional examples, it was confirmed that the present invention reduces the maximum plate thickness reduction rate at the tip of the flange portion 33 located on the extension of the valley line 3c of the top plate, thereby suppressing cracking. [Explanation of Symbols]

[0039] 1 Press-formed product 3. Top panel 3a First top panel 3b Second top plate section 3c Tenpandani Line 5. Ridge section 7 Vertical wall section 9 punches 9a Punching shoulder 9b Top plate valley line forming part 11 pads 13 Dies 13b Diaphragm 15 Blank 17 Intermediate molded products 19 Intermediate top plate section 19a First intermediate top plate section 19b Second Intermediate Top Panel 19c Intermediate top plate valley line 20 Intermediate vertical wall section 21. Intermediate ridge section 22 Intermediate step valley section 23 Step-shaped section 25 Outer part 27-step forming punch 29-step molding die 31 Press-formed product (Example) 33 Flange section

Claims

1. A method for manufacturing a press-formed product having a top plate portion and a vertical wall portion continuous with the top plate portion via a ridge portion, wherein the top plate portion has a top plate valley line that intersects the ridge line, and the top plate portion comprises a first top plate portion and a second top plate portion on either side of the top plate valley line, A first molding step for press molding an intermediate molded product having an intermediate top plate valley line, a first intermediate top plate portion and a second intermediate top plate portion provided on either side of the intermediate top plate valley line, an intermediate ridge portion formed in the portion corresponding to the ridge line portion, an intermediate vertical wall portion continuous with the intermediate ridge portion, a step-shaped portion consisting of a step including an intermediate step valley portion continuous with the intermediate vertical wall portion, and an outer surface portion extending outward in connection with the step-shaped portion, A method for manufacturing a press-formed product, comprising a second molding step of press-forming the intermediate molded product into the press-formed product.

2. The method for manufacturing a press-formed product according to claim 1, characterized in that the press-formed product manufactured by press forming has a top plate portion, a vertical wall portion continuous with the top plate portion via the ridge portion, and a flange portion continuous with the vertical wall portion.

3. The method for manufacturing a press-formed product according to claim 1 or 2, characterized in that the radius of curvature of the intermediate ridge portion of the intermediate molded product is the same as or greater than the radius of curvature of the ridge portion of the press-formed product.

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