Manufacturing method for press-formed products

Abstract

When press-forming a tailored blank into an elongated flange shape, the aim is to suppress stress concentration at the weld end without creating a recess near the weld end. [Solution] A method for manufacturing a press-formed product by press-forming a tailored blank into an elongated flange shape, comprising: holding the tailored blank between a first die and a pad, bending it with a second die; and during bending, the second die first contacts the first steel plate side of the tailored blank, which has lower strength, and forms a vertical wall while contacting the second steel plate.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a press-formed product by press-forming a tailored blank into an elongation flange shape.

Background Art

[0002] Patent Document 1 describes a method of press-forming an assembly blank formed by butting and welding a plurality of steel plates into an elongation flange shape, in which a portion close to the welded end of the blank is recessed inside the blank from the welded end.

[0003] According to this manufacturing method, by recessing the portion close to the welded end of the assembly blank, stress concentration at the welded end of the assembly blank during press-forming can be suppressed, and cracking at the welded end can be prevented. Further, this manufacturing method can also be used for press-forming a tailored blank obtained by welding steel plates having at least one of different strengths and thicknesses into an elongation flange shape.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the manufacturing method described in Patent Document 1, since it is necessary to recess the portion close to the welded end of the blank, depending on the final formed product, it is necessary to remove the recess, and there is a problem that the number of steps for removing the recess increases.

[0006] For example, if the final molded product is installed in a vehicle, the presence of a recess could lead to damage during a vehicle collision or other impact, potentially causing the recess to break. Therefore, in such cases, the recess must be removed, adding an extra step to the process.

[0007] One aspect of this disclosure is to enable the suppression of stress concentration at the weld end when press-forming a tailored blank into an elongated flange shape, without creating a recess near the weld end. [Means for solving the problem]

[0008] A method for manufacturing a press-formed product according to one aspect of the present disclosure is a method for manufacturing a press-formed product by press-forming a tailored blank, obtained by welding steel plates having at least one of different strengths and thicknesses, into an elongated flange shape.

[0009] This manufacturing method includes clamping a tailored blank between a first die and a pad, bending it with a second die, and during bending, having the second die first contact the first steel plate side of the tailored blank, which has lower strength, and forming the vertical wall while contacting the second steel plate.

[0010] According to the manufacturing method of the present disclosure, when press-forming a tailored blank into an elongated flange shape, the second die first contacts the first steel plate, which has low strength in the tailored blank, and then contacts the remaining processing area from the first steel plate to the second steel plate.

[0011] Therefore, during press working, stress is generated not only at the weld line ends between the first steel plate and the second steel plate, but also at the point where the first die first strikes the first steel plate, allowing the stress applied to the weld line ends to be distributed to the first steel plate side.

[0012] Therefore, according to the manufacturing method of the present disclosure, it is possible to suppress the concentration of stress at the weld end and the occurrence of cracks at the weld end without providing a recess near the weld end of the tailored blank.

[0013] In a tailored blank, the first steel plate with lower strength is the one with lower strength among the two steel plates welded together. For example, if the strengths are the same, it will be the steel plate with the thinner thickness. If the strengths and thicknesses differ, the first steel plate is the one with the lower overall strength, including the thickness.

[0014] Here, the second die may include a first region that first contacts the first steel sheet during bending, a second region that contacts the weld line of the tailored blank, and a third region having an inclined surface connecting the first region and the second region.

[0015] In this case, when press-forming a tailored blank into an elongated flange shape, the second die can gradually form a vertical wall between the inclined surfaces of the first and third regions from the time the first region contacts the first steel plate until the second region contacts the weld line. Therefore, the stress applied to the end of the weld line during press-forming can be distributed more effectively.

[0016] In this case, during bending, the intersection of the second and third regions of the second die may be positioned near the weld line. This way, bending of the entire first steel plate begins in the third region before stress is applied near the weld line in the second region, thus better suppressing the stress applied to the weld line end during press working.

[0017] Furthermore, the second region of the second die may be parallel to the surface of the tailored blank. In this way, bending of the remaining processing area of ​​the tailored blank is started simultaneously in the second region of the second die, and bending of that processing area can be performed well.

[0018] Next, in a top view of the tailor-made blank as viewed from above the plate surface where the steel plates are welded, at least a part of the outer periphery may be curved, and a weld line may be arranged at the curved portion. In this case, in the manufacturing method of the present disclosure, by the above-described pressing process, a vertical wall having an extended flange shape may be formed at the curved portion.

[0019] In this way, a press-formed product can be manufactured in which the plate surface of the outer periphery of the curved portion of the tailor-made blank is bent downward to form a vertical wall. Further, during the manufacturing, it is possible to suppress cracks from occurring in the weld line due to the stress applied to the end portion of the weld line arranged at the curved portion.

[0020] Note that the manufacturing method of the present disclosure is not limited to a method of forming a vertical wall by pressing the outer peripheral portion of the plate surface curved in a top view. For example, it can also be used to press-process a curved portion of the plate surface of the tailor-made blank into an extended flange shape in a side view as viewed from the side.

[0021] Next, the second mold may be divided into a first split mold that contacts the first steel plate during bending formation and a second split mold that contacts the remaining processing area from the first steel plate to the second steel plate. In this case, by disposing an elastic body between the first split mold and the second split mold, after the first split mold contacts the first steel plate, the elastic body is compressed by the movement of the second split mold so that the second split mold contacts the processing area.

[0022] Even in this way, when press-forming the tailor-made blank into an extended flange shape, in the second mold, first, the first split mold contacts the first steel plate, and then the second split mold contacts the remaining processing area, and the same effect as described above can be obtained.

Brief Description of the Drawings

[0023] [Figure 1] It is a perspective view schematically showing the press-formed product of the first embodiment. [Figure 2] It is a plan view showing the state of an intermediate product before press-processing the processing area 8 shown in FIG. 1. [Figure 3]It is a perspective view showing a press-forming die used for press-forming the machining area 8 shown in FIG. 1. [Figure 4] It is an explanatory view showing an X-X cross section of the die (second die) shown in FIG. 3. [Figure 5] It is a perspective view showing the die (second die) of the second embodiment. [Figure 6] It is a perspective view showing the die of the press-forming apparatus of the third embodiment. [Figure 7] It is a plan view of the die (second die) shown in FIG. 6 as viewed from above. [Figure 8] It is an explanatory view for explaining a method of press-forming an intermediate product using the die (second die) shown in FIG. 7. [Figure 9] It is an explanatory view showing the shape of a vertical wall portion of a press-molded product that can be manufactured using the die (second die) shown in FIG. 7. [Mode for Carrying Out the Invention]

[0024] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [First Embodiment] [Press-Molded Product] The press-molded product 1 shown in FIG. 1 is produced by press-forming a tailored blank 10. Hereinafter, the thickness direction of the press-molded product 1 and the tailored blank 10 is referred to as the vertical direction. Also, with respect to the first steel plate 21 described later, the direction in which the second steel plate 22 is arranged is referred to as the left-right direction. Further, the longitudinal direction of the second steel plate 12 is referred to as the front-back direction. Note that these directions are defined for convenience of explanation and do not limit the usage mode of the press-molded product 1.

[0025] As an example, the press-molded product 1 is used as a rear floor panel mounted on a vehicle. The press-molded product 1 includes a top plate portion 2, a side wall portion 3, and a flange portion 4. The top plate portion 2 is a plate-like portion that spreads in the same plane, and has a substantially rectangular shape in a top view seen from a direction perpendicular to the plate surface. Note that arbitrary concavities and convexities may be provided on the top plate portion 2.

[0026] The side wall portion 3 is a plate-like portion that is erected from the edge of the top plate portion 2, surrounding the top plate portion 2. More specifically, the side wall portion 3 is a wall that extends downward from the front edge, the left edge, and the right edge of the top plate portion 2. In other words, the side wall portion 3 is a wall that surrounds the top plate portion 2 from three directions. Therefore, the top plate portion 2 and the side wall portion 3 of the press-formed product 1 have a bag-shaped outer form.

[0027] A bag shape is defined as a shape that allows for the storage of objects within a space and has an opening for inserting and removing objects. Therefore, in the press-formed product 1, objects can be stored in the space enclosed by the top plate portion 2 and the side wall portion 3. Furthermore, objects can be inserted and removed through the opening formed on the opposite side of the side wall portion 3 from the top plate portion 2.

[0028] In this embodiment, the side wall portion 3 extends from the bottom to the top, slightly inclined towards the top plate portion 2. In other words, the cross-sections perpendicular to the front-to-back direction in the top plate portion 2 and the side wall portion 3 are trapezoidal. Also, the cross-section perpendicular to the vertical direction in the side wall portion 3 is roughly U-shaped.

[0029] The flange portion 4 is a plate-like portion that extends from the side wall portion 3 in a direction intersecting the side wall portion 3, and is positioned to surround the top plate portion 2 when viewed from a direction perpendicular to the plate surface. More specifically, the flange portion 4 is a plate that extends from the edge of the side wall portion 3 opposite to the top plate portion 2, away from the top plate portion 2, and approximately parallel to the top plate portion 2. In other words, the flange portion 4 is a plate that surrounds the top plate portion 2 from three directions when viewed from above.

[0030] As shown in Figures 1 and 2, the press-formed product 1 comprises a central steel plate 20 in which the top plate portion 2 and side wall portions 3 are formed by a first press working of the tailored blank 10, and a first steel plate 21 and a second steel plate 22 arranged to the left and right of the central steel plate 20.

[0031] Figure 2 is a plan view showing the right half of the press-formed product 1, but the left half of the press-formed product 1, which is not shown, is constructed symmetrically to the right half of the press-formed product 1. Also, Figure 2 shows an intermediate product 1A after the top plate portion 2 and side wall portion 3 have been formed by the first press working of the tailored blank 10, and before the flange portion 4 is press-formed into an elongated flange shape by the second press working described later.

[0032] Here, in the tailored blank 10 before press working, the central steel plate 20 is a roughly rectangular plate-shaped member, for example, with a plate thickness of 0.6 mm and a tensile strength of 270 MPa. Furthermore, the second steel plate 22 is positioned on both the left and right sides of the central steel plate 20, is long in the front-to-back direction, and is a rectangular plate-shaped member with the same length as the central steel plate 20. Its thickness is greater than that of the central steel plate 20, and its tensile strength is higher than that of the central steel plate 20. For example, the thickness of the second steel plate 22 is 1.0 mm, and its tensile strength is 780 MPa.

[0033] Furthermore, the first steel plate 21 is positioned on the opposite side of the central steel plate 20 of the left and right second steel plates 22, in other words, on the outside. It is a plate-shaped member whose length in the front-to-back direction is shorter than the second rear half, its thickness is thinner than that of the second steel plate 22, and its tensile strength is lower than that of the second steel plate 22. For example, the thickness of the first steel plate 21 is 0.65 mm, and its tensile strength is 270 MPa. The difference in tensile strength between the first steel plate 21 and the second steel plate 22 can be obtained not only from the thickness, but also, for example, by using different materials.

[0034] Therefore, in this embodiment, the first steel plate 21 has lower strength than the second steel plate 22. The difference in strength between the first steel plate 21 and the second steel plate 22 can be determined, for example, by comparing the values ​​obtained by multiplying the tensile strength of each steel plate 21 and 22 by their thickness, even if the steel plates have the same tensile strength or thickness.

[0035] The first steel plates 21 are positioned on both the left and right ends of the press-formed product 1, and the second steel plates 22 are positioned between the left and right first steel plates 21 and the central steel plate 20. The second steel plates 22 are joined to the left and right edges of the central steel plate 20 by welding. The left and right edges of the central steel plate 20 are almost straight in shape, and the weld line WL1 between the left and right edges of the central steel plate 20 and the two second steel plates 22 is a straight line extending in the front-to-back direction.

[0036] In the second steel plate 22, the outer edge opposite to the weld line WL1 between it and the central steel plate 20 widens away from the weld line WL1 from the front and rear of the press-formed product 1 toward the central portion. Furthermore, the outer edge of the second steel plate 22 is straight from the central portion furthest from the weld line WL1 toward the rear, and the first steel plate 21 is welded to this straight portion. Thus, the left and right flange portions 4 of the press-formed product 1 are composed of the second steel plate 22 and the first steel plate 21, and the rear of the left and right flange portions 4 are widened to the left and right by the first steel plate 21.

[0037] The weld line WL2 between the first steel plate 21 and the second steel plate 22 has the same straight shape as the weld line WL1, but the second steel plate 22 extends forward from the front end of the weld line WL2. Therefore, the first steel plate 21 and the second steel plate 22 are curved from the outer edge of the second steel plate 22 toward the front edge of the first steel plate 21, and the front end of the weld line WL2 is located in this curved portion 24.

[0038] In the intermediate product 1A shown in Figure 2, the entire area from the outer edge of the second steel plate 22, including the curved portion 24, to the front edge of the first steel plate 21 is set as the processing area 8 for the second press working. In the second press working, the processing area 8, including the curved portion 24, is press-formed into an elongated flange shape, forming the vertical wall 6 shown in Figure 1.

[0039] This second press working is a process of press working the processing area 8, which includes the curved portion 24 of the first steel plate 21 and the second steel plate 22, into an elongated flange shape, and is the main step of the manufacturing method disclosed herein. Next, the manufacturing method of the press-formed product 1 by this second press working will be described.

[0040] [Manufacturing method (second press processing)] In the second press working process, a press forming apparatus equipped with a die 31, a punch 32, and a pad 33 is used, as shown in Figure 3. Figure 3 shows the intermediate product 1A to be processed, and the right half of the die 31, punch 32, and pad 33 that make up the press forming apparatus. The left half, which is not shown, is configured symmetrically to the right half.

[0041] The punch 32 corresponds to the first die of this disclosure and is positioned below the plate surface of the intermediate product 1A. The pad 33 is for fixing the intermediate product 1A by clamping it from above and below between itself and the punch 32, and is positioned above the plate surface of the intermediate product 1A.

[0042] The contact surfaces of the punch 32 and pad 33 with the intermediate product 1A have the same shape as the upper and lower surfaces of the intermediate product 1A, including the top plate portion 2, side wall portion 3, and flange portion 4. In addition, the surface dimensions of the punch 32 and pad 33 are smaller than those of the intermediate product 1A by the amount of the vertical wall 6 of the processing area 8, so that the die 31 can bend and form the processing area 8 of the intermediate product 1A.

[0043] The die 31 corresponds to the second mold of this disclosure and is positioned above the punch 32 and pad 33 that hold the intermediate product 1A before press working. The die 31 also has a side wall 31A with the same curved shape as the processing area 8 that includes the curved portion 24 in the intermediate product 1A. During press working, the die 31 is moved downward relative to the punch 32 and pad 33 that hold the intermediate product 1A via a drive mechanism (not shown).

[0044] As a result, during press working, the die 31 strikes the upper surface of the processing area 8, which includes the curved portion 24, in the intermediate product 1A, bending the processing area 8 of the intermediate product 1A downwards. Furthermore, since the inside of the processing area 8 of the intermediate product 1A is held by the punch 32, when the die 31 moves relatively downwards, the processing area 8 of the intermediate product 1A is bent downwards along the side wall 32A of the punch 32. In other words, the processing area 8 of the intermediate product 1A is sandwiched between the side wall 31A of the die 31 and the side wall 32A of the punch 32, and is press-formed into an elongated flange shape, thereby forming a vertical wall 6.

[0045] In Figure 3, only the surfaces of the die 31, punch 32, and pad 33 are shown to make it easier to understand the surface shapes that come into contact with the upper and lower surfaces of the intermediate product 1A during press working. However, in reality, each die has thickness in the vertical direction.

[0046] [Die (second mold) configuration] By the way, if the lower surface 31B of the die 31 that contacts the processing area 8 of the intermediate product 1A is made into a plane parallel to the plate surface of the flange portion 4, then during press working of the processing area 8, stress will concentrate at the end of the weld line WL2 located in the curved portion 24 of the intermediate product 1A. This is because the end of the weld line WL2 has the lowest strength in the curved portion 24, and when stress concentrates at the end of the weld line WL2, cracks are more likely to form in the weld line WL2.

[0047] Therefore, in this embodiment, a step 40 is provided on the lower surface 31B of the die 31 so as to distribute the stress applied to the end of the weld line WL2 in the processing area 8 of the intermediate product 1A and to suppress the formation of cracks at the end of the weld line WL2.

[0048] As shown in Figure 4, this step 40 is formed by dividing the lower surface 31B of the die 31 into a first region 41, a second region 42, and a third region 43 connecting the first region 41 and the second region 42.

[0049] Of these, the first region 41 is set to the lowest position in the vertical direction so that it first contacts the first steel plate 21, which has lower strength, on either side of the weld line WL2 during press working. The second region 42 is set to a height position where, during press working, the die 31 moves further downward after the first region 41 has contacted the first steel plate 21, and then contacts the weld line WL2. The third region 43 is set as an inclined surface connecting the first region 41 and the second region 42.

[0050] Furthermore, the third region 43 is set such that, when the bending of the processing region 8 by press working occurs, the intersection point P with the second region 42 is located near the weld line WL2. Also, the second region 42 is set such that the side of the second steel plate 22 from the intersection point P with the third region 43 is parallel to the surface of the second steel plate 22 (in other words, the surface of the tailored blank 10 to be processed).

[0051] [effect] As described above, in this embodiment, in the intermediate product 1A obtained by press working the tailored blank 10, the processing regions 8, including the curved portions 24 on both the left and right ends, are bent into an elongated flange shape by a second press working process. The contact surface of the die 31 used in the press working process with respect to the processing region 8 is divided into first to third regions 41 to 43 such that it contacts the first steel plate 21 first when the processing region 8 is bent.

[0052] Therefore, in the second press working, the first region 41 of the die 31 contacts the first steel sheet 21 in the processing region 8 of the intermediate product 1A, and bending begins from the contact position 26 (see Figure 2) toward the processing region 8 on the first steel sheet 21 side. Subsequently, the inclined surface of the third region 43 of the die 31 causes bending to proceed in the processing region 8 from the contact position 26 of the first steel sheet 21 toward the first steel sheet 21 and the welding line WL2. Furthermore, when the second region 42 of the die 31 reaches near the welding line WL2, the second region 42 contacts the processing region 8 on the second steel sheet 22 side, and the remaining portion of the processing region 8 is bent.

[0053] Thus, during the second press working, the die 31 first contacts the first steel plate 21, which has lower strength, resulting in a large stress being applied to the contact point 26 and causing the first steel plate 21 to deform. Subsequently, as the press working progresses, stress is applied to the end of the weld line WL2.

[0054] Therefore, according to this embodiment, when press-forming the processing area 8 into an elongated flange shape, the stress applied to the end of the weld line WL2 can be distributed to the first steel plate 21 side, thereby suppressing the occurrence of cracks at the end of the weld line WL2.

[0055] Furthermore, during bending, the intersection point P of the second region 42 and the third region 43 of the die 31 is positioned near the weld line WL2 in the processing region 8. Therefore, bending of almost the entire first steel plate 21 begins in the third region 43 before stress is applied near the weld line WL2 in the second region 42. Thus, the stress applied to the end of the weld line WL2 during press working can be suppressed more effectively.

[0056] Furthermore, the second region 42 of the die 31 is set to be parallel to the plate surface of the processing region 8. Therefore, when the second region 42 of the die 31 comes into contact with the plate surface of the processing region 8, the entire remaining area of ​​the processing region 8, where bending has not yet begun, is bent almost simultaneously, allowing for good bending of the remaining processing region 8.

[0057] [Second Embodiment] In the first embodiment, the lower surface 31B of the die 31, which is the contact surface with the processing area 8, is divided into first to third regions 41 to 43, and the third region 43, which connects the first region 41 and the second region 42, which are of different heights, is made up of an inclined surface.

[0058] In contrast, in this embodiment, as shown in Figure 5, the third region 43 on the lower surface 31B of the die 31 is configured in a stepped shape rather than an inclined surface. Even in this manner, when press-forming the processing area 8 into an elongated flange shape, the stress applied to the end of the weld line WL2 can be distributed to the first steel plate 21 side, and the same effects as in the first embodiment can be obtained.

[0059] Furthermore, when shaping the third region 43 into a staircase, the number of steps may be two, as shown in Figure 5, or it may be even more. [Third Embodiment] In the first and second embodiments described above, the lower surface 31B of the die 31, which is the contact surface with the processing area 8, is divided into first to third areas 41 to 43, thereby distributing the stress applied to the end of the weld line WL2 when the processing area 8 is press-formed into an elongated flange shape towards the first steel plate 21.

[0060] In contrast, in this embodiment, as shown in Figures 6 and 7, the die 31 is divided into a first die 51 that contacts the first steel sheet 21 during bending, and a second die 52 that contacts the remaining processing area 8A from the first steel sheet 21 to the second steel sheet 22.

[0061] Then, when press-forming the processing area 8 into an elongated flange shape, as shown in Figure 8, an elastic body 53 is placed between the first die 51 and the second die 52 so that the first die 51 contacts the first steel plate 21, and then the second die 52 contacts the remaining processing area 8A.

[0062] In this way, before the press working begins, the height of the contact surface of the second die 52 with respect to the processing area 8 can be made higher than that of the first die 51 via the elastic body 53. Then, when the press working begins and the entire die 31 moves toward the processing area 8 via a drive mechanism (not shown), the first die 51 comes into contact with the predetermined contact position 26 of the first steel sheet 21 before the second die 52.

[0063] During press working, the die 31 continues to move via the drive mechanism. When the first die 51 contacts the first steel sheet 21 and bending begins at the contact position 26, the elastic body 53 is gradually compressed as the bending progresses. As a result, the height of the second die 52 relative to the processing area 8 gradually approaches the height of the first die 51, and the second die 52 comes into contact with the remaining processing area 8A, initiating bending in the remaining processing area 8A as well.

[0064] Therefore, even if the die 31 is composed of a first die 51, a second die 52, and an elastic body 53, as in this embodiment, when press-forming the processing area 8 into an elongated flange shape, the stress applied to the end of the weld line WL2 can be distributed to the first steel plate 21 side. Thus, the same effects as in the first and second embodiments can be obtained in this embodiment as well.

[0065] The elastic body 53 can be made of an elastic material such as a spring or a gas spring, but its elasticity needs to be adjusted appropriately so that the second die 52 comes into contact with the remaining processing area 8A after the bending process by the first die 51 has begun.

[0066] Furthermore, the elastic body 53 may be configured such that the heights of the first die 51 and the second die 52 are aligned when the bending of the processing area 8 is completed. In this way, as shown in Figure 9, the press working of the processing area 8 can form not only the vertical wall 6 but also a flange 7 extending from the lower edge of the vertical wall 6 into the inside of the curved portion 24.

[0067] However, in order to do this, as shown in Figure 6, it is necessary to provide the punch 32 with a bottom portion 32B that extends from the side wall 32A inward into the curved portion 24. In this embodiment, the first die 51 corresponds to the first split mold of this disclosure, and the second die 52 corresponds to the second split mold of this disclosure.

[0068] [Other embodiments] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0069] For example, in the above embodiment, the case of manufacturing a rear floor panel of a vehicle as press-formed product 1 was described, but the manufacturing method of the present disclosure can also be used to manufacture press-formed products other than the rear floor panel, such as the front pillar and center pillar of a vehicle. In other words, the manufacturing method of the present disclosure can be applied in the same manner as in the above embodiment to any press-formed product in which a region including a weld line in a tailored blank is formed into an elongated flange shape by press working, and the same effects can be obtained.

[0070] Furthermore, the above embodiment described a case in which the curved outer periphery of the plate surface of a tailored blank is press-formed into an elongated flange shape when viewed from above. However, the manufacturing method of the present disclosure can also be used to press-form the curved portion of the plate surface of a tailored blank into an elongated flange shape when viewed from the side.

[0071] Furthermore, 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. Also, some parts of the configuration of the above embodiment may be omitted. In addition, at least some parts of the configuration of the above embodiment may be added to, replaced, etc., in the configuration of other above embodiments.

[0072] [Technical concepts disclosed in this specification] [Item 1] A manufacturing method for producing a press-formed product by press-forming a tailored blank, obtained by welding steel plates having different strengths and thicknesses, into an elongated flange shape, The tailored blank is held between the first mold and a pad, and then bent and formed using the second mold. During the bending process, the second die first contacts the first steel plate side, which has lower strength in the tailored blank, and forms the vertical wall while contacting the second steel plate. A method for manufacturing press-formed products, including the method described above.

[0073] [Item 2] A method for manufacturing a press-formed product as described in item 1, A method for manufacturing a press-formed product, comprising: a second die comprising: a first region that first contacts the first steel sheet during bending; a second region that contacts the weld line of the tailored blank; and a third region having an inclined surface connecting the first region and the second region.

[0074] [Item 3] A method for manufacturing a press-formed product as described in item 2, A method for manufacturing a press-formed product, wherein, during the bending process, the intersection of the second region and the third region of the second mold is positioned near the weld line.

[0075] [Item 4] A method for manufacturing a press-formed article as described in item 2 or item 3, A method for manufacturing a press-formed product, wherein the second region of the second mold is parallel to the sheet surface of the tailored blank.

[0076] [Item 5] A method for manufacturing a press-formed product as described in any one of items 1 to 4, In the tailored blank, when viewed from above with the plate surface where the steel plates are welded, at least a portion of the outer circumference is curved, and the weld line is located in the curved portion. A method for manufacturing a press-formed product, wherein a vertical wall having the elongated flange shape is formed in the curved portion by the aforementioned press working.

[0077] [Item 6] A method for manufacturing a press-formed product as described in item 1, The second die is divided into a first dividing die that contacts the first steel plate during bending, and a second dividing die that corresponds to the remaining processing area from the first steel plate to the second steel plate. A method for manufacturing a press-formed product, wherein an elastic body is placed between the first dividing die and the second dividing die, which is compressed by the movement of the second dividing die after the first dividing die contacts the first steel sheet, causing the second dividing die to contact the processing area. [Explanation of Symbols]

[0078] 1... Press-formed product, 10... Tailored blank, 21... First steel plate, 22... Second steel plate, 31... Die, 32... Punch, 33... Pad.

Claims

1. A manufacturing method for producing a press-formed product by press-forming a tailored blank, obtained by welding steel plates having different strengths and thicknesses, into an elongated flange shape, The tailored blank is held between the first mold and a pad, and then bent and formed using the second mold. During the bending process, the second die first contacts the first steel plate side, which has lower strength in the tailored blank, and forms the vertical wall while contacting the second steel plate. A method for manufacturing press-formed products, including the method described above.

2. The method for manufacturing a press-formed product according to claim 1, wherein the second die comprises a first region that first contacts the first steel sheet during bending, a second region that contacts the weld line of the tailored blank, and a third region having an inclined surface connecting the first region and the second region.

3. The method for manufacturing a press-formed product according to claim 2, wherein, during the bending process, the intersection of the second region and the third region of the second mold is positioned near the weld line.

4. The method for manufacturing a press-formed product according to claim 2, wherein the second region of the second mold is parallel to the sheet surface of the tailored blank.

5. In the tailored blank, when viewed from above with the plate surface where the steel plates are welded, at least a portion of the outer circumference is curved, and the weld line is located in the curved portion. A method for manufacturing a press-formed product according to any one of claims 1 to 4, wherein a vertical wall having the elongated flange shape is formed in the curved portion by the aforementioned press working.

6. The second die is divided into a first dividing die that contacts the first steel plate during bending, and a second dividing die that corresponds to the remaining processing area from the first steel plate to the second steel plate. A method for manufacturing a press-formed product according to claim 1, wherein an elastic body is placed between the first dividing die and the second dividing die, which is compressed by the movement of the second dividing die after the first dividing die contacts the first steel sheet, causing the second dividing die to contact the processing area.

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