Press-forming device and manufacturing method for press-formed product

Abstract

To prevent unnecessary deformation of a workpiece obtained by butt-welding two steel plates in press forming.SOLUTION: A press-forming device for performing press forming on a workpiece in which a first steel plate and a second steel plate are joined by butt-welding, includes a clamping structure configured to clamp the workpiece. The butt-welding is welding between an end face of the first steel plate and an end face of the second steel plate at a boundary between the first steel plate and the second steel plate. The clamping structure is configured to clamp a first region of the first steel plate and the second steel plate which are adjacent to the boundary, as a specific region in the workpiece, and not to clamp a second region that is farther away from the boundary than the first region and includes the first steel plate and the second steel plate adjacent to the first region.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a press forming apparatus. [Background technology]

[0002] Press forming using a tailored blank as a workpiece is known. A tailored blank is a blank material formed by joining two steel plates together by butt welding. For example, Patent Document 1 discloses a technique for performing press forming while clamping a tailored blank between a punch and a counter punch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-218501 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art such as that disclosed in Patent Document 1, there are cases where there is a large difference in thickness or strength between the two steel sheets in the tailored blank, or where only one of the two steel sheets in the tailored blank is clamped between the punch and the counter punch, etc. In these cases, when press forming is performed using the tailored blank as a workpiece, stress is concentrated in one of the steel sheets, causing problems such as deformation or breakage.

[0005] One aspect of the present disclosure is to suppress unnecessary deformation of a workpiece formed by butt-welding two steel plates during press forming. [Means for solving the problem]

[0006] One aspect of the present disclosure is a press-forming device for press-forming a workpiece in which a first steel plate and a second steel plate are butt-welded, the press-forming device including a clamping structure configured to clamp the workpiece. The butt welding is performed by welding an end face of the first steel plate to an end face of the second steel plate at the boundary between the first and second steel plates. The clamping structure is configured to clamp a first region of the first and second steel plates adjacent to the boundary as a specific region of the workpiece, but not to clamp a second region of the first and second steel plates adjacent to the first region, which is further from the boundary than the first region.

[0007] According to this configuration, press forming is performed with the butt-welded portions of the first and second steel plates clamped by the clamping structure. Furthermore, because there are areas not clamped by the clamping structure, the area of the area clamped by the clamping structure is smaller than when the entire workpiece is clamped, and therefore the pressure applied to the first and second steel plates by the clamping structure increases. Therefore, during press forming, movement of the first and second steel plates in the areas clamped by the clamping structure is suppressed, and unnecessary deformation of the workpiece formed by butt-welding two steel plates can be suppressed.

[0008] In one aspect of the present disclosure, the clamping structure may clamp the workpiece along the boundary. With this clamping structure, press forming is performed with the butt-welded portions of the first and second steel plates clamped by the clamping structure, which prevents the first and second steel plates from moving during press forming, thereby preventing unnecessary deformation of the workpiece.

[0009] In one aspect of the present disclosure, the clamping structure may be configured to clamp an end of a weld line that is a butt-welded portion of a workpiece. With this configuration, the area of the workpiece clamped by the clamping structure during press forming is small, so the pressure applied to the first steel plate and the second steel plate from the clamping structure increases, which prevents the first steel plate and the second steel plate from moving during press forming, thereby preventing unnecessary deformation of the workpiece formed by butt-welding two steel plates.

[0010] In one embodiment of the present disclosure, at least one of the plate thickness and strength of the first steel plate and the second steel plate may be different from each other. By press-forming a workpiece including such a first steel plate and a second steel plate using the above-mentioned press-forming device, unnecessary deformation of the workpiece can be suppressed.

[0011] In one embodiment of the present disclosure, the first steel plate and the second steel plate may have different plate thicknesses, and the clamping structure may have a step in the plate thickness direction of the first steel plate and the second steel plate corresponding to the difference in plate thickness between the first steel plate and the second steel plate so that the clamping structure can clamp the surfaces of both the first steel plate and the second steel plate.

[0012] With this configuration, the first steel plate and the second steel plate are both clamped by a clamping structure, which makes it possible to suppress unnecessary deformation of the workpiece formed by butt-welding two steel plates having different plate thicknesses.

[0013] In one aspect of the present disclosure, the first region may be smaller than the second region. With this configuration, the area of the first region clamped by the clamping structure is small, and therefore the pressure applied to the workpiece from the clamping structure is increased, which suppresses movement of the first steel plate and the second steel plate during press forming, thereby suppressing unnecessary deformation of the workpiece formed by butt-welding two steel plates.

[0014] One aspect of the present disclosure is a manufacturing method for a press-formed product formed by press-forming a workpiece in which a first steel plate and a second steel plate are butt-welded, the method including clamping the workpiece and press-forming at least one of the first steel plate and the second steel plate in the plate thickness direction. The butt welding is welding an end face of the first steel plate to an end face of the second steel plate at the boundary between the first and second steel plates. The clamping includes clamping a first region of the first and second steel plates adjacent to the boundary as a specific region of the workpiece, and not clamping a second region of the first and second steel plates adjacent to the first region, which is further from the boundary than the first region.

[0015] This manufacturing method provides the same effects as the press molding device described above. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] 3A and 3B are cross-sectional views of the press-forming device and the tailored blank in a positioning step and a recess forming step, respectively. [Figure 4] 4A and 4B are cross-sectional views of the press-forming device and the tailored blank in a clamping step and a wall-forming step, respectively. [Figure 5] 1 is a flowchart showing a method for manufacturing a press-molded product. [Figure 6] FIG. 10 is a cross-sectional view of a second punch having a step and a tailored blank in a wall portion forming step according to another embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a pad having a step and a tailored blank in a wall forming step according to another embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a second punch having a step, a pad, and a tailored blank in a wall portion forming step according to another embodiment. [Figure 9] 10A and 10B are diagrams illustrating clamping of the end of the weld line in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First embodiment] [1-1.Configuration] [1-1-1. Composition of press-molded products] The press-formed product 1 shown in FIGS. 1 and 2 is formed by press-forming a tailored blank 2 shown in FIG. 3A. The tailored blank 2 is a blank material in which a first steel plate 21 and second steel plates 22a, 22b, which have different plate thicknesses, are joined by butt welding to form an integrated body. Press forming includes bending forming, drawing forming, and the like. The press-formed product 1 is a component that forms part of the center floor pan of an automobile. The press-formed product 1 may be a component other than the center floor pan of an automobile, such as a rocker outer panel or other floor panel. The press-formed product 1 may also be a component that is installed in a vehicle other than an automobile.

[0018] The press-formed product 1 includes a first plate-shaped portion 11 and second plate-shaped portions 12a and 12b. The first plate-shaped portion 11 is a substantially rectangular plate-shaped portion. The first plate-shaped portion 11 corresponds to the first steel plate 21 in the tailored blank 2 before being press-formed. The first plate-shaped portion 11 has a first end face and a second end face extending in a first direction perpendicular to the plate thickness direction, on both sides of a second direction perpendicular to both the first direction and the plate thickness direction of the first plate-shaped portion 11. The first and second directions are indicated by double-headed arrows in Figures 1 and 2. The two sides of the second direction of the first plate-shaped portion 11 refer to the first and second sides of the second direction of the first plate-shaped portion 11. The first and second sides of the second direction correspond to the first and second end sides of the double-headed arrows (specifically, the leading and trailing end sides of the double-headed arrows).

[0019] The second plate-shaped portions 12a, 12b are each joined to an end face of the first plate-shaped portion 11 by butt welding. The second plate-shaped portions 12a, 12b have shapes symmetrical with respect to the first plate-shaped portion 11. The second plate-shaped portion 12a has an end face extending in a first direction, and this end face is joined to a first end face of the first plate-shaped portion 11 by butt welding. The second plate-shaped portion 12b has an end face extending in the first direction, and this end face is joined to a second end face of the first plate-shaped portion 11 by butt welding. In other words, the butt welding is provided at boundaries 13a, 13b between the first plate-shaped portion 11 and the second plate-shaped portions 12a, 12b. In the press-formed product 1, the portion where the first plate-shaped portion 11 and the second plate-shaped portion 12a are butt-welded is called the weld line 14a, and the portion where the first plate-shaped portion 11 and the second plate-shaped portion 12b are butt-welded is called the weld line 14b. The second plate-shaped portions 12a and 12b correspond to the second steel plates 22a and 22b in the tailored blank 2 before being press-formed.

[0020] The second plate-shaped portions 12a and 12b have butt portions 121a and 121b, wall portions 122a and 122b, and plate-shaped end portions 123a and 123b, respectively. The butt portions 121a and 121b, the wall portions 122a and 122b, and the plate-shaped end portions 123a and 123b are obtained by press-forming the second steel plates 22a and 22b.

[0021] The butt joints 121a and 121b are plate-shaped portions extending in the first and second directions, and each have a portion that is joined to the first plate-shaped portion 11 by butt welding.

[0022] The walls 122a and 122b protrude in the thickness direction of the second plate-shaped portions 12a and 12b from the ends of the butt joints 121a and 121b opposite the portions joined to the first plate-shaped portion 11 in the second direction, and extend in the first direction. The walls 122a and 122b are provided near the weld lines 14a and 14b.

[0023] The plate-like ends 123a and 123b extend in the second direction away from the first plate-like portion 11 from the ends of the wall portions 122a and 122b opposite to the ends connected to the butt portions 121a and 121b.

[0024] One or more recesses 15 recessed in the thickness direction of the first plate-shaped portion 11 are formed on the surface of the first plate-shaped portion 11. The depth of the recesses 15 is smaller than the length by which the wall portions 122a, 122b protrude from the butt portions 121a, 121b and is smaller than the thickness of the first plate-shaped portion 11. The recesses 15 may be formed at least partially on the surfaces of the second plate-shaped portions 12a, 12b across the boundaries 13a, 13b. The shape of the recesses 15 in a cross section perpendicular to the thickness direction is not particularly limited and may be, for example, approximately circular or approximately rectangular. The recesses 15 do not have to be formed in the first plate-shaped portion 11 and the second plate-shaped portions 12a, 12b.

[0025] [1-1-2. Tailored Blank Structure] The press-formed product 1 is formed by press-forming the tailored blank 2 using press-forming devices 5a and 5b (see FIGS. 3A, 3B, 4A, and 4B).

[0026] The tailored blank 2 is a blank material formed by joining a first steel plate 21 and second steel plates 22a, 22b, which have different thicknesses, together by butt welding. The first steel plate 21 is a substantially rectangular plate-shaped member. As an example, the thickness of the first steel plate 21 is 0.6 mm, and the tensile strength of the first steel plate 21 is 270 MPa. The first steel plate 21 has a first end face and a second end face extending in a first direction, on both sides of the first steel plate 21 in a second direction. The both sides of the first steel plate 21 in the second direction refer to the first side and the second side of the first steel plate 21 in the second direction.

[0027] The second steel plates 22a, 22b are plate-shaped members. The second steel plates 22a, 22b are high-tensile steel plates, and the thicknesses of the second steel plates 22a, 22b are greater than the thickness of the first steel plate 21. For example, the thicknesses of the second steel plates 22a, 22b may be at least twice the thickness of the first steel plate 21. As an example, the thicknesses of the second steel plates 22a, 22b are 1.8 millimeters, and the tensile strengths of the second steel plates 22a, 22b are 780 MPa. The second steel plates 22a, 22b are joined to the end faces of the first steel plate 21 by butt welding. The second steel plates 22a, 22b have shapes symmetrical with respect to the first steel plate 21. The second steel plate 22a has an end face extending in a first direction, and the end face is joined to a first end face of the first steel plate 21 by butt welding. The second steel plate 22b has an end face extending in the first direction, and this end face is joined to the second end face of the first steel plate 21 by butt welding. That is, the butt welds are provided at boundaries 13a, 13b between the first steel plate 21 and the second steel plates 22a, 22b. In the tailored blank 2, the butt-welded portion of the first steel plate 21 and the second steel plate 22a corresponds to the weld line 14a in the press-formed product 1, and the butt-welded portion of the first steel plate 21 and the second steel plate 22b corresponds to the weld line 14b in the press-formed product 1.

[0028] [1-1-3. Configuration of press forming equipment] The method for manufacturing the press-formed product 1 includes a step of forming the recessed portion 15 in the tailored blank 2 by the press forming device 5a, and a step of forming the wall portions 122a, 122b in the tailored blank 2 by the press forming device 5b.

[0029] As shown in FIGS. 3A and 3B , the press-forming apparatus 5a includes a first punch 51a, a first die 52a, and a holder 53. The press-forming apparatus 5a is positioned so as to sandwich the tailored blank 2 from both sides in the thickness direction of the tailored blank 2. Hereinafter, the thickness direction of the tailored blank 2 is referred to as the vertical direction. The thickness direction is not limited to the vertical direction, but may also be interpreted as the left-right direction or the front-rear direction. The terms "up" and "down" in the vertical direction may be interpreted interchangeably. In this embodiment, the vertical direction in FIG. 1 refers to the vertical direction when the press-formed product 1 is mounted on a vehicle, and is therefore referred to as the vehicle vertical direction. The vertical direction in FIGS. 3 , 4 , 6 , 7 , and 8 refers to the vertical direction in press forming, and is therefore referred to as the press vertical direction. The press vertical direction is opposite to the vehicle vertical direction. In other words, press forming is performed with the tailored blank 2 that forms the press-formed product 1 upside down relative to the state in which the press-formed product 1 is mounted on a vehicle.

[0030] The first punch 51a is a punch of a die used in press forming. The first punch 51a is located below the tailored blank 2. The upper surface of the first punch 51a faces the boundaries 13a and 13b of the tailored blank 2, the entire first steel plate 21, and parts of the second steel plates 22a and 22b.

[0031] The first punch 51a has a first punch-side recess forming portion 511 for forming recesses 15 in the tailored blank 2. The first punch-side recess forming portion 511 is provided on the surface of the first punch 51a that faces the tailored blank 2 and protrudes upward. The number of first punch-side recess forming portions 511 provided is the same as the number of recesses 15 formed in the tailored blank 2.

[0032] The first die 52a is a die for a metal mold used in press forming. The first die 52a is positioned above the tailored blank 2 so as to cover the entire tailored blank 2. The first die 52a has first die side recess forming portions 521 for forming recess portions 15 in the tailored blank 2. The first die side recess forming portions 521 are provided on the surface of the first die 52a that faces the tailored blank 2, and are recessed upward so as to fit into the first punch side recess forming portions 511. The number of first die side recess forming portions 521 provided is the same as the number of recess portions 15 to be formed in the tailored blank 2.

[0033] The holders 53 are holders for supporting the tailored blank 2. The holders 53 are located below the tailored blank 2. The holders 53 are located on both sides of the first punch 51a in the second direction. The upper surfaces of the holders 53 face parts of the second steel plates 22a, 22b.

[0034] The holder 53 is configured so as to be able to move downward together with the first die 52a by being pressed downward by the first die 52a positioned above the holder 53. 4A and 4B, the press forming apparatus 5b includes a second punch 51b, a second die 52b, and a pad 54. The press forming apparatus 5b is positioned so as to sandwich the tailored blank 2 from both the top and bottom sides of the tailored blank 2. The tailored blank 2 placed in the press forming apparatus 5b is the tailored blank 2 that has been press-formed by the press forming apparatus 5a.

[0035] The second punch 51b is a punch of a die used in press forming. The second punch 51b is located below the tailored blank 2. The upper surface of the second punch 51b faces the entire tailored blank 2.

[0036] The second punch 51b has second punch sidewall forming portions 512a, 512b for forming the wall portions 122a, 122b in the tailored blank 2. The second punch sidewall forming portions 512a, 512b are provided on the surface of the second punch 51b that faces the tailored blank 2, and have a step in the vertical direction.

[0037] The second die 52b is a die for a metal mold used in press forming. The second die 52b is located above the tailored blank 2 so as to cover the entire tailored blank 2. The second die 52b has second die sidewall forming portions 522a, 522b for forming wall portions 122a, 122b in the tailored blank 2. The second die sidewall forming portions 522a, 522b are provided on the surface of the second die 52b that faces the tailored blank 2, and have vertical steps so as to fit into the second punch sidewall forming portions 512a, 512b.

[0038] The pad 54 is a pad for clamping the tailored blank 2 during press forming. The pad 54 is arranged to pass through the second die 52b. The pad 54 is located above the tailored blank 2. The lower surface of the pad 54 faces the boundaries 13a, 13b, part of the first steel plate 21, and part of the second steel plates 22a, 22b in the tailored blank 2. A gas cushion (not shown) is arranged above the pad 54. The pad 54 is configured to be able to clamp the tailored blank 2 by the pressure it receives from the gas cushion.

[0039] [1-2. Manufacturing methods for press-molded products] 5, the method for manufacturing the press-formed product 1 includes a arranging step S10, a recessed portion forming step S20, a clamping step S30, and a wall portion forming step S40. The method for manufacturing the press-formed product 1 is performed in the order of the arranging step S10, the recessed portion forming step S20, the clamping step S30, and the wall portion forming step S40.

[0040] [1-2-1. Formation of recessed area] A method for manufacturing the press-formed product 1 will be described with reference to FIGS. 3A, 3B, 4A, and 4B. The arrangement step S10 and the recessed portion forming step S20 are steps for forming recessed portions 15 in the tailored blank 2 by the press forming apparatus 5a shown in FIGS. 3A and 3B.

[0041] As shown in FIG. 3A , in the placement step S10, the tailored blank 2 is placed on the upper surface of the holder 53. The second steel plates 22a, 22b of the tailored blank 2 are supported by the holder 53 by partially abutting against the upper surface of the holder 53. The first steel plate 21 of the tailored blank 2 is spaced apart from both the first punch 51a and the holder 53. The first steel plate 21 may have a portion that abuts against the upper surface of the first punch 51a. The tailored blank 2 is spaced apart from the first die 52a located above the tailored blank 2.

[0042] In the recess forming step S20, the first die 52a moves downward and comes into contact with the upper surface of the tailored blank 2. Thereafter, the first die 52a, the tailored blank 2, and the holder 53 move downward together. After moving downward until it comes into contact with the first punch 51a, the tailored blank 2 is deformed along the first punch-side recess forming portion 511 of the first punch 51a and the first die-side recess forming portion 521 of the first die 52a due to the pressure received from the first punch 51a, which is moving further downward. This press forming forms a recess 15 in the tailored blank 2, and a first plate-like portion 11 having the recess 15 is obtained (see FIG. 3B).

[0043] [1-2-2. Formation of the wall] The clamping step S30 and the wall portion forming step S40 are steps for forming the walls 122a and 122b in the tailored blank 2 by the press forming device 5b shown in FIGS. 4A and 4B.

[0044] 4A, in the clamping step S30, the tailored blank 2 is clamped between a second punch 51b located below the tailored blank 2 and a pad 54 located above the tailored blank 2. The tailored blank 2 is spaced apart from a second die 52b located above the tailored blank 2.

[0045] The pads 54 clamp the boundaries 13a, 13b including the weld lines 14a, 14b in the tailored blank 2 and first regions 26a, 26b adjacent to the boundaries 13a, 13b along the boundaries 13a, 13b. The pads 54 do not clamp second regions 27 of the first steel plate 21 and the second steel plates 22a, 22b adjacent to the first regions 26a, 26b, which are regions of the tailored blank 2 that are farther from the boundaries 13a, 13b than the first regions 26a, 26b. The first regions 26a, 26b are smaller than the second regions 27.

[0046] In this embodiment, the pad 54 clamps, as first regions 26a and 26b, the vicinity of the boundaries 13a and 13b in the tailored blank 2. In this embodiment, the pad 54 clamps, as second region 27, the region in the tailored blank 2 other than the vicinity of the boundaries 13a and 13b.

[0047] In the wall portion forming step S40, with the tailored blank 2 sandwiched between the second punch 51b and the pad 54, the second die 52b moves downward and abuts against the upper surfaces of the second steel plates 22a, 22b in the tailored blank 2. Thereafter, the tailored blank 2 is subjected to pressure from the second die 52b, which continues to move downward, causing the tailored blank 2 to deform along the second punch sidewall forming portions 512a, 512b of the second punch 51b and the second die sidewall forming portions 522a, 522b of the second die 52b. This press forming forms the walls 122a, 122b in the tailored blank 2, thereby obtaining second plate-like portions 12a, 12b having butt portions 121a, 121b, wall portions 122a, 122b, and plate-like end portions 123a, 123b (see FIG. 4B ).

[0048] In the wall portion forming step S40, the second punch 51b, the pad 54, and the first steel plate 21 of the tailored blank 2 do not move. [1-3. Actions and Effects] According to the embodiment described above in detail, the following actions and effects can be obtained.

[0049] (1a) In the wall portion forming step S40, when the tailored blank 2 is deformed along the second punch sidewall forming portions 512a, 512b and the second die sidewall forming portions 522a, 522b due to pressure from the second die 52b, a force is applied to the weld lines 14a, 14b in a direction that causes the first steel plate 21 and the second steel plates 22a, 22b to peel away from each other in the second direction. At this time, stress may concentrate on one of the first steel plate 21 and the second steel plates 22a, 22b, causing cracks or deformation. In particular, the first steel plate 21, which is made of a material having a thin plate thickness or low tensile strength, is prone to stress concentration and cracks or deformation.

[0050] In contrast, in the above embodiment, the pad 54 clamps the boundaries 13a, 13b including the weld lines 14a, 14b in the tailored blank 2 and the first regions 26a, 26b adjacent to the boundaries 13a, 13b along the boundaries 13a, 13b.

[0051] Furthermore, the pad 54 does not clamp the second region 27 of the first steel plate 21 and the second steel plate 22a, 22b adjacent to the first region 26a, 26b, which is located in the tailored blank 2 farther from the boundaries 13a, 13b than the first region 26a, 26b.

[0052] According to this process, the area over which the pads 54 clamp the tailored blank 2 is smaller than when the pads 54 clamp both the first regions 26a, 26b and the second region 27, particularly when the pads 54 clamp the entire region of the tailored blank 2 that does not require press forming. Therefore, the pressure (hereinafter referred to as pressing pressure) applied by the pads 54 to the tailored blank 2 increases when the pads 54 clamp the tailored blank 2. A high pressing pressure suppresses movement of the first steel plate 21 and the second steel plate 22a, 22b in the tailored blank 2 during press forming, such as in the wall forming step S40, thereby reducing the rate at which the thickness of the tailored blank 2 is reduced by press forming. This suppresses deformation and cracking of the first steel plate 21 and the second steel plate 22a, 22b, particularly in the first regions 26a, 26b, including the vicinity of the weld lines 14a, 14b. Therefore, unnecessary deformation of the tailored blank 2 can be suppressed.

[0053] (1b) The pad 54 clamps both the first steel plate 21 and the second steel plates 22a, 22b in the clamping step S30 and the wall portion forming step S40. This configuration can prevent stress from concentrating on either the first steel plate 21 or the second steel plates 22a, 22b during press forming, which can prevent deformation or cracks from occurring in the tailored blank 2 compared to when the pad 54 clamps either the first steel plate 21 or the second steel plates 22a, 22b.

[0054] (1c) The first regions 26a and 26b where the pads 54 hold the tailored blank 2 are smaller than the second region 27 where the pads 54 do not hold the tailored blank 2. This configuration makes it possible to further reduce the area over which the pad 54 holds the tailored blank 2, thereby further increasing the pressing pressure of the pad 54. As a result, unnecessary deformation of the tailored blank 2 can be further suppressed.

[0055] (1d) In the above-described manufacturing method of the press-molded product 1, a recess 15 is formed in the tailored blank 2 in the placement process S10 and the recess forming process S20, and then walls 122a, 122b are formed in the tailored blank 2 in the clamping process S30 and the wall forming process S40.

[0056] According to these processes, recesses 15 are formed in the tailored blank 2 in the clamping step S30 and the wall portion forming step S40. Therefore, in the clamping step S30 and the wall portion forming step S40, the pad 54 only needs to clamp the first regions 26a, 26b of the tailored blank 2, where deformation and cracking are likely to occur, and there is no need to clamp any regions other than the first regions 26a, 26b. This makes it possible to further reduce the area over which the pad 54 clamps the tailored blank 2, and to increase the pressing pressure of the pad 54. This therefore makes it possible to further suppress unnecessary deformation of the tailored blank 2.

[0057] [1-4. Correspondence between terms] In the above embodiment, the tailored blank 2 corresponds to an example of a workpiece, and the pad 54 and the second punch 51b correspond to an example of a clamping structure.

[0058] 2. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0059] (2a) In the above embodiment, the pad 54 sandwiches the vicinity of the boundaries 13a and 13b of the tailored blank 2 as the first regions 26a and 26b. However, the first regions 26a and 26b in which the pads 54 hold the tailored blank 2 are not limited to the vicinity of the boundaries 13a and 13b. That is, the first regions 26a and 26b may extend beyond the vicinity of the boundaries 13a and 13b.

[0060] (2b) In the above embodiment, the pad 54 does not sandwich the second region 27 of the tailored blank 2 other than the vicinity of the boundaries 13a and 13b. However, the area where the pad 54 does not hold the tailored blank 2 is not limited to the above example.

[0061] The pad 54 may be arranged so as not to sandwich a part of the region of the tailored blank 2 opposite the side where deformation due to press forming occurs with respect to the boundaries 13a, 13b, and this region serves as the second region 27. For example, in the wall forming step S40, the pad 54 may be arranged so as not to sandwich a part of the region between the boundaries 13a and 13b, which region serves as the side opposite the side where the walls 122a, 122b are formed by press forming with respect to the boundaries 13a, 13b, in the tailored blank 2.

[0062] (2c) In the above embodiment, the first regions 26a, 26b where the pads 54 clamp the tailored blank 2 are smaller than the second region 27 where the pads 54 do not clamp the tailored blank 2. However, the area of the first regions 26a, 26b where the pads 54 clamp the tailored blank 2 may be equal to or larger than the area of the second region 27. It is sufficient that the pads 54 clamp at least the areas near the weld lines 14a, 14b on both the first steel plate 21 and the second steel plates 22a, 22b, and that there are portions that are not clamped other than the areas near the weld lines 14a, 14b.

[0063] (2d) As in the above embodiment, when the first steel plate 21 and the second steel plates 22a, 22b in the tailored blank 2 have different plate thicknesses, at least one of the pad 54 and the second punch 51b may have a step corresponding to the difference in plate thickness. Specifically, at least one of the pad 54 and the second punch 51b may have a step corresponding to the difference in plate thickness between the first steel plate 21 and the second steel plates 22a, 22b in the plate thickness direction of the first steel plate 21 and the second steel plates 22a, 22b so as to be able to clamp the surfaces of the first steel plate 21 and the second steel plates 22a, 22b.

[0064] For example, as shown in FIG. 6, when there is a step on the lower surface at the boundary 13b of the tailored blank 2, the second punch 251b may have a punch-side step 261 corresponding to the difference in plate thickness between the first steel plate 21 and the second steel plates 22a, 22b at the boundaries 13a, 13b.

[0065] Alternatively, as shown in Figure 7, if there is a step on the upper surface of the boundary 13b of the tailored blank 2, the pad 354 may have a pad-side step 362 that corresponds to the difference in plate thickness between the first steel plate 21 and the second steel plates 22a, 22b at the boundaries 13a, 13b.

[0066] Alternatively, as shown in FIG. 8, when there are steps on both the upper and lower surfaces at the boundary 13b of the tailored blank 2, the second punch 251b and the pad 354 may have a punch-side step 261 and a pad-side step 362, respectively, that correspond to the difference in plate thickness between the first steel sheet 21 and the second steel sheets 22a and 22b at the boundaries 13a and 13b.

[0067] With this configuration, even in a tailored blank 2 in which the two steel plates have a large difference in thickness, the second punch 251b and the pad 354 can clamp the surfaces of both the first steel plate 21 and the second steel plates 22a, 22b. This makes it possible to prevent cracks and deformations from occurring in the tailored blank 2.

[0068] (2e) In the above embodiment, the first steel plate 21 and the second steel plates 22a, 22b have different plate thicknesses and tensile strengths. However, at least one of the plate thicknesses and tensile strengths of the first steel plate 21 and the second steel plates 22a, 22b may be the same.

[0069] As an example, the first steel plate 21 and the second steel plates 22a, 22b may have the same thickness and tensile strength, and the tensile strength of the first steel plate 21 and the second steel plates 22a, 22b may both be 780 MPa or higher. In this case, the areas near the weld lines 14a, 14b are likely to soften due to the heat caused by welding, and stress is likely to concentrate therein. Therefore, by using the pads 54 to clamp the areas near the weld lines 14a, 14b, it is possible to prevent cracks and deformation in the tailored blank 2.

[0070] As an example, the first steel plate 21 and the second steel plates 22a, 22b may have the same plate thickness and tensile strength, and the first steel plate 21 and the second steel plates 22a, 22b may both be stainless steel. In this case, the weld lines 14a, 14b of the tailored blank 2 are likely to break in the wall portion forming step S40. Therefore, by clamping the vicinity of the weld lines 14a, 14b with the pads 54, it is possible to prevent cracks and deformation of the tailored blank 2.

[0071] (2f) In the above embodiment, in the clamping step S30, the pads 54 clamp the boundaries 13a, 13b, including the weld lines 14a, 14b, of the tailored blank 2 along the boundaries 13a, 13b. However, the pads 54 do not need to clamp the entire boundaries 13a, 13b and the weld lines 14a, 14b, and may clamp only the boundaries 13a, 13b and the weld lines 14a, 14b. The pads 54 do not need to directly clamp the weld lines 14a, 14b as long as they clamp the vicinity of the weld lines 14a, 14b of the tailored blank 2. For example, the pads 54 may clamp only the ends of the weld lines 14a, 14b, or other portions that are prone to cracking, rather than the entire weld lines 14a, 14b.

[0072] As an example, as shown in Fig. 9, the first region 26a held by the pad 54 may be a part of the boundary 13a including part of the weld line 14a between the first steel plate 21 and the second steel plate 22a. In Fig. 9, the hatched region indicates the first region 26a held by the pad 54. The solid lines indicate the ridge lines and boundary 13a between the first steel plate 21 and the second steel plate 22a. The thick lines indicate the weld line 14a. The dashed lines indicate the ridge lines of the press-formed product 1 after virtual press forming. The dashed lines indicate the portions where the wall portions 122a are formed during press forming.

[0073] This configuration makes it possible to further reduce the area over which the pad 54 holds the tailored blank 2, thereby further increasing the pressing pressure of the pad 54. As a result, unnecessary deformation of the tailored blank 2 can be further suppressed.

[0074] (2g) In the above embodiment, the manufacturing method of the press-formed product 1 is performed in the order of the arrangement step S10, the recessed portion forming step S20, the clamping step S30, and the wall portion forming step S40. However, the arrangement step S10 and the recessed portion forming step S20 do not have to be performed before the clamping step S30 and the wall portion forming step S40. In particular, if the press-formed product 1 does not have a recessed portion 15, the arrangement step S10 and the recessed portion forming step S20 do not have to be performed.

[0075] (2h) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0076] [Technical idea disclosed in this specification] [Item 1] A press forming apparatus for press forming a workpiece in which a first steel plate and a second steel plate are joined by butt welding, a clamping structure configured to clamp the workpiece, The butt welding is welding between an end surface of the first steel plate and an end surface of the second steel plate at a boundary between the first steel plate and the second steel plate, The clamping structure is configured to clamp a first region of the first steel plate and the second steel plate adjacent to the boundary as a specific region of the workpiece, and not to clamp a second region of the first steel plate and the second steel plate adjacent to the first region, which is a region farther from the boundary than the first region. Press forming equipment.

[0077] [Item 2] The press molding apparatus according to item 1, The clamping structure clamps the workpiece along the boundary. Press forming equipment.

[0078] [Item 3] The press forming apparatus according to item 1 or 2, The clamping structure is configured to clamp an end of a weld line, which is the butt-welded portion of the workpiece. Press forming equipment.

[0079] [Item 4] The press forming apparatus according to any one of items 1 to 3, At least one of a plate thickness and a strength of the first steel plate and the second steel plate is different from each other. Press forming equipment.

[0080] [Item 5] Item 4. The press molding apparatus according to item 4, The first steel plate and the second steel plate have different plate thicknesses, The clamping structure has a step in the thickness direction of the first steel plate and the second steel plate according to the difference in plate thickness between the first steel plate and the second steel plate so that the surfaces of both the first steel plate and the second steel plate can be clamped. Press forming equipment.

[0081] [Item 6] The press forming apparatus according to any one of items 1 to 5, The first region is smaller than the second region. Press forming equipment.

[0082] [Item 7] A method for manufacturing a press-formed product formed by press-forming a workpiece in which a first steel plate and a second steel plate are joined by butt welding, clamping the workpiece; Press-forming at least one of the first steel plate and the second steel plate in a plate thickness direction; Including, The butt welding is welding between an end surface of the first steel plate and an end surface of the second steel plate at a boundary between the first steel plate and the second steel plate, The clamping includes clamping a first region of the first steel plate and the second steel plate adjacent to the boundary as a specific region of the workpiece, and not clamping a second region of the first steel plate and the second steel plate that is a region farther from the boundary than the first region and adjacent to the first region. Manufacturing method for press-molded products. [Explanation of symbols]

[0083] 1...press-formed product, 2...tailored blank, 5a, 5b...press forming device, 13a, 13b...boundary, 21...first steel plate, 22a, 22b...second steel plate, 26a, 26b...first region, 27...second region, 51b, 251b...second punch, 54, 354...pad, S30...clamping process, S40...wall forming process.

Claims

1. A press forming apparatus for performing press forming on a workpiece in which a first steel plate and a second steel plate are joined by butt welding, a clamping structure configured to clamp the workpiece, The butt welding is welding between an end surface of the first steel plate and an end surface of the second steel plate at a boundary between the first steel plate and the second steel plate, The clamping structure is configured to clamp a first region of the first steel plate and the second steel plate adjacent to the boundary as a specific region of the workpiece, and not to clamp a second region of the first steel plate and the second steel plate adjacent to the first region, which is a region farther from the boundary than the first region. Press forming equipment.

2. The press forming apparatus according to claim 1, The clamping structure clamps the workpiece along the boundary. Press forming equipment.

3. The press forming apparatus according to claim 1, The clamping structure is configured to clamp an end of a weld line, which is the butt-welded portion of the workpiece. Press forming equipment.

4. The press forming apparatus according to claim 1, At least one of a plate thickness and a strength of the first steel plate and the second steel plate is different from each other. Press forming equipment.

5. The press forming apparatus according to claim 4, The first steel plate and the second steel plate have different plate thicknesses, The clamping structure has a step in the thickness direction of the first steel plate and the second steel plate corresponding to the difference in plate thickness between the first steel plate and the second steel plate so that the surfaces of both the first steel plate and the second steel plate can be clamped. Press forming equipment.

6. The press forming apparatus according to any one of claims 1 to 5, The first region is smaller than the second region. Press forming equipment.

7. A method for manufacturing a press-formed product formed by press-forming a workpiece in which a first steel plate and a second steel plate are joined by butt welding, clamping the workpiece; Press-forming at least one of the first steel plate and the second steel plate in a plate thickness direction; Including, The butt welding is welding between an end surface of the first steel plate and an end surface of the second steel plate at a boundary between the first steel plate and the second steel plate, The clamping includes clamping a first region of the first steel plate and the second steel plate adjacent to the boundary as a specific region of the workpiece, and not clamping a second region of the first steel plate and the second steel plate that is a region farther from the boundary than the first region and adjacent to the first region. Manufacturing method for press-molded products.

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