Press molding apparatus and method for manufacturing press-molded products

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] This disclosure relates to a press forming apparatus.

Background Art

[0002] Press forming using a tailored blank as the workpiece is known. A tailored blank is a blank material formed by butt-welding two steel plates together. For example, Patent Document 1 discloses a technique for performing press forming while sandwiching a tailored blank between a punch and a counterpunch.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art as disclosed in Patent Document 1, there are cases where the difference in plate thickness or strength between the two steel plates in the tailored blank is large, or only one of the two steel plates in the tailored blank is sandwiched between the punch and the counterpunch. In these cases, when press forming is performed using the tailored blank as the workpiece, there is a problem that stress concentrates on one steel plate, resulting in deformation, fracture, etc.

[0005] One aspect of this disclosure is to suppress unnecessary deformation of a workpiece in which two steel plates are butt-welded in press forming.

Means for Solving the Problems

[0006] One aspect of the present disclosure is 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, comprising a clamping structure configured to clamp the workpiece. The butt welding is welding of the end face of the first steel plate and the end face of the second steel plate at the 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 that is further from the boundary than the first region and adjacent to the first region.

[0007] With this configuration, press forming is performed with the butt-welded portion of the first and second steel plates being held between the clamping structure. Furthermore, since there are areas not held by the clamping structure, the area held by the clamping structure is smaller than when the entire workpiece is held, thus increasing the pressure applied to the first and second steel plates by the clamping structure. As a result, during press forming, movement of the first and second steel plates in the area held by the clamping structure is suppressed, and unwanted deformation of the workpiece, which consists of two steel plates butt-welded together, can be suppressed.

[0008] In one aspect of this disclosure, the clamping structure may clamp the workpiece along the boundary. With this type of clamping, press forming is performed with the butt-welded portions of the first and second steel plates clamped by the clamping structure. As a result, movement of the first and second steel plates is suppressed during press forming, and unwanted deformation of the workpiece can be suppressed.

[0009] In one aspect of this disclosure, the clamping structure may be configured to clamp the end of a weld line, which is a butt-welded portion of the workpiece. With this configuration, during press forming, the area of ​​the workpiece clamped by the clamping structure is small, which increases the pressure applied from the clamping structure to the first and second steel plates. As a result, the movement of the first and second steel plates is suppressed during press forming, and unwanted deformation of the workpiece, which is formed by butt-welding two steel plates, can be suppressed.

[0010] In one aspect of this disclosure, at least one of the thickness and strength of the first steel plate and the second steel plate may differ from one another. By press-forming a workpiece including such a first steel plate and a second steel plate using the press-forming apparatus described above, unnecessary deformation of the workpiece can be suppressed.

[0011] In one aspect of this disclosure, the first steel plate and the second steel plate may have different thicknesses. The clamping structure may have a step in the thickness direction of the first steel plate and the second steel plate corresponding to the difference in thickness between the first steel plate and the second steel plate, so as to be able to clamp both surfaces of the first steel plate and the second steel plate.

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

[0013] In one aspect of this 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, which increases the pressure applied to the workpiece by the clamping structure. As a result, the movement of the first and second steel plates during press forming is suppressed, and unwanted deformation of the workpiece, which is formed by butt-welding two steel plates, can be suppressed.

[0014] One aspect of the present disclosure is 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, comprising: clamping the workpiece; and press forming at least one of the first steel plate and the second steel plate in the thickness direction. Butt welding is welding of the end face of the first steel plate and the end face of the second steel plate at the boundary between the first steel plate and the second steel plate. 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 further from the boundary than the first region and adjacent to the first region.

[0015] This manufacturing method produces the same effects as the press molding apparatus described above. [Brief explanation of the drawing]

[0016] [Figure 1] This is a perspective view of a press-formed product. [Figure 2] This is a top view of a press-formed product. [Figure 3] Figure 3A is a cross-sectional view of the press forming apparatus and tailored blank during the placement process. Figure 3B is a cross-sectional view of the press forming apparatus and tailored blank during the recess formation process. [Figure 4] Figure 4A is a cross-sectional view of the press forming apparatus and tailored blank during the clamping process. Figure 4B is a cross-sectional view of the press forming apparatus and tailored blank during the wall forming process. [Figure 5] This is a flowchart illustrating the manufacturing method of press-formed products. [Figure 6] This is a cross-sectional view of a stepped second punch and a tailored blank in the wall forming process of another embodiment. [Figure 7] This is a cross-sectional view of a pad with a step and a tailored blank in the wall forming process of another embodiment. [Figure 8] This is a cross-sectional view of a stepped second punch, pad, and tailored blank in the wall forming process of another embodiment. [Figure 9] This is a diagram for explaining clamping the end of a weld line in another embodiment.

Embodiments for Carrying out the Invention

[0017] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First Embodiment] [1-1. Structure] [1-1-1. Structure of Press-formed Product] The press-formed product 1 shown in FIGS. 1 and 2 is formed by press-forming the tailored blank 2 shown in FIG. 3A. The tailored blank 2 is a blank material in which the first steel plate 21 having a different plate thickness and the second steel plates 22a and 22b are joined by butt welding, so that the first steel plate 21 and the second steel plates 22a and 22b are integrated. The press-forming includes bending, drawing, and the like. The press-formed product 1 is a part constituting a 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, for example, a rocker outer panel or another floor panel. The press-formed product 1 may be a component mounted on other than an automobile.

[0018] The press-formed product 1 includes a first plate-like portion 11 and second plate-like portions 12a and 12b. The first plate-like portion 11 is a substantially rectangular plate-like part. The first plate-like portion 11 corresponds to the first steel plate 21 in the tailored blank 2 before press-forming. The first plate-like 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 in a second direction perpendicular to both the first direction and the plate thickness direction in the first plate-like portion 11. The first direction and the second direction are indicated by double-headed arrows in FIGS. 1 and 2. Both sides in the second direction in the first plate-like portion 11 refer to the first side and the second side in the second direction in the first plate-like portion 11. The first side and the second side in the second direction correspond to the first end side and the second end side of the double-headed arrows (specifically, the tip side and the rear end side of the double-headed arrows).

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

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

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

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

[0023] The plate-like ends 123a and 123b, respectively, extend in a direction away from the first plate-like portion 11 in a second direction, from the end opposite to the end connected to the abutting portion 121a and 121b at the wall portion 122a and 122b.

[0024] One or more recesses 15 are formed on the surface of the first plate-like portion 11, recessed in the thickness direction of the first plate-like portion 11. The depth of the recesses 15 is less than the length by which the wall portions 122a, 122b protrude from the abutting portions 121a, 121b, and less than the thickness of the first plate-like portion 11. The recesses 15 may be formed on the surface of the second plate-like portions 12a, 12b at least partially, straddling 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, substantially circular or substantially rectangular. The recesses 15 do not necessarily have to be formed on the first plate-like portion 11 and the second plate-like portions 12a, 12b.

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

[0026] Tailored Blank 2 is a blank material formed by joining a first steel plate 21 and second steel plates 22a and 22b, which have different thicknesses, by butt welding. The first steel plate 21 is a substantially rectangular plate-shaped member. For example, the thickness of the first steel plate 21 is 0.6 millimeters, 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 sides of the first steel plate 21 in a second direction refer to the first side and the second side of the first steel plate 21 in a second direction.

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

[0028] [1-1-3. Configuration of the press molding machine] The method for manufacturing the press-formed product 1 comprises the steps of forming a recess 15 in the tailored blank 2 using a press forming device 5a, and forming walls 122a and 122b in the tailored blank 2 using a press forming device 5b.

[0029] As shown in Figures 3A and 3B, the press forming apparatus 5a comprises a first punch 51a, a first die 52a, and a holder 53. The press forming apparatus 5a is positioned 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 will be 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-back direction. The "up" and "down" in the vertical direction may be interpreted as mutually interchangeable. In this embodiment, the vertical direction in Figure 1 is 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 Figures 3, 4, 6, 7, and 8 is the vertical direction in press forming, and is therefore referred to as the press vertical direction. The press vertical direction is the opposite of the vehicle vertical direction. That is, press forming is performed with the vertical orientation of the tailored blank 2 forming the press-formed product 1 reversed compared to when the press-formed product 1 is mounted on a vehicle.

[0030] The first punch 51a is a punch in the die used in press forming. The first punch 51a is located on the underside of the tailored blank 2. The upper surface of the first punch 51a faces the boundaries 13a, 13b of the tailored blank 2, the entirety of the first steel plate 21, and parts of the second steel plates 22a, 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 facing the tailored blank 2 and protrudes upward. The same number of first punch-side recess-forming portions 511 are provided as the number of recesses 15 formed in the tailored blank 2.

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

[0033] The holder 53 is a holder for supporting the tailored blank 2. The holder 53 is located on the underside of the tailored blank 2. The holder 53 is located on both sides of the first punch 51a in the second direction. The upper surface of the holder 53 faces a portion of the second steel plates 22a, 22b.

[0034] The holder 53 is configured to move downward together with the first die 52a by being pressed downward from the first die 52a located above the holder 53. As shown in Figures 4A and 4B, the press forming apparatus 5b comprises a second punch 51b, a second die 52b, and a pad 54. The press forming apparatus 5b is positioned to sandwich the tailored blank 2 from both the upper and lower sides. The tailored blank 2 placed in the press forming apparatus 5b is the tailored blank 2 after press forming by the press forming apparatus 5a.

[0035] The second punch 51b is a die punch in press forming. The second punch 51b is located on the underside of 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 side wall forming portions 512a and 512b for forming wall portions 122a and 122b on the tailored blank 2. The second punch side wall forming portions 512a and 512b are provided on the surface of the second punch 51b facing the tailored blank 2 and have a step in the vertical direction.

[0037] The second die 52b is a die in the press forming process. The second die 52b is located on the upper side of the tailored blank 2 so as to cover the entire tailored blank 2. The second die 52b has second die side wall forming portions 522a and 522b for forming wall portions 122a and 122b on the tailored blank 2. The second die side wall forming portions 522a and 522b are provided on the surface of the second die 52b facing the tailored blank 2 and have vertical steps to fit into the second punch side wall forming portions 512a and 512b.

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

[0039] [1-2. Method for manufacturing press-formed products] As shown in Figure 5, the manufacturing method for press-formed product 1 comprises a placement step S10, a recess formation step S20, a clamping step S30, and a wall formation step S40. The manufacturing method for press-formed product 1 is performed in the following order: placement step S10, recess formation step S20, clamping step S30, and wall formation step S40.

[0040] [1-2-1. Formation of recessed areas] The manufacturing method of press-formed product 1 will be explained using Figures 3A, 3B, 4A, and 4B. The placement process S10 and the recess formation process S20 are steps in which a recess 15 is formed in the tailored blank 2 using the press forming apparatus 5a shown in Figures 3A and 3B.

[0041] As shown in Figure 3A, in the positioning step S10, the tailored blank 2 is positioned on the upper surface of the holder 53. The second steel plates 22a and 22b of the tailored blank 2 are supported by the holder 53 by partially contacting the upper surface of the holder 53. The first steel plate 21 of the tailored blank 2 is separated from both the first punch 51a and the holder 53. The first steel plate 21 may have a portion that contacts the upper surface of the first punch 51a. The tailored blank 2 is separated from the first die 52a located above the tailored blank 2.

[0042] In the recess formation step S20, the first die 52a moves downward and contacts the upper surface of the tailored blank 2. Subsequently, the first die 52a, the tailored blank 2, and the holder 53 move downward together. After the tailored blank 2 moves downward until it contacts the first punch 51a, it deforms 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 moves further downward. This press forming creates a recess 15 in the tailored blank 2, and a first plate-like portion 11 having the recess 15 is obtained (see Figure 3B).

[0043] [1-2-2. Formation of the wall] The clamping process S30 and the wall formation process S40 are steps in which walls 122a and 122b are formed on the tailored blank 2 using the press forming apparatus 5b shown in Figures 4A and 4B.

[0044] As shown in Figure 4A, in the clamping process S30, the tailored blank 2 is clamped by the second punch 51b located below the tailored blank 2 and the pad 54 located above the tailored blank 2. The tailored blank 2 is separated from the second die 52b located above the tailored blank 2.

[0045] The pad 54 clamps the boundaries 13a, 13b, which include the weld lines 14a, 14b, and the first regions 26a, 26b adjacent to the boundaries 13a, 13b, along the boundaries 13a, 13b. The pad 54 does not clamp the second region 27 of the first steel plate 21 and the second steel plates 22a, 22b, which are further from the boundaries 13a, 13b than the first regions 26a, 26b, and are adjacent to the first regions 26a, 26b. The first regions 26a, 26b are smaller than the second region 27.

[0046] In this embodiment, the pad 54 clamps the vicinity of the boundaries 13a and 13b in the tailored blank 2 as the first regions 26a and 26b. In this embodiment, the pad 54 does not clamp any region other than the vicinity of the boundaries 13a and 13b in the tailored blank 2 as the second region 27.

[0047] In the wall formation process S40, with the tailored blank 2 held between the second punch 51b and the pad 54, the second die 52b moves downward and contacts the upper surfaces of the second steel plates 22a and 22b on the tailored blank 2. Subsequently, the tailored blank 2 deforms along the second punch side wall forming portions 512a and 512b of the second punch 51b and the second die side wall forming portions 522a and 522b of the second die 52b due to the pressure received from the second die 52b, which moves further downward. This press forming creates wall portions 122a and 122b on the tailored blank 2, and second plate-like portions 12a and 12b having butt portions 121a and 121b, wall portions 122a and 122b, and plate-like ends 123a and 123b (see Figure 4B).

[0048] In the wall forming process 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 embodiments described in detail above, the following actions and effects can be obtained.

[0049] (1a) In the wall formation process S40, when the tailored blank 2 deforms along the second punch side wall forming sections 512a, 512b and the second die side wall forming sections 522a, 522b due to the pressure received 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 separate in the second direction. At this time, stress may concentrate on one of the steel plates, the first steel plate 21 and the second steel plates 22a, 22b, which may cause cracking or deformation. In particular, the first steel plate 21, which is made of the material with a thinner thickness or lower tensile strength, is more prone to stress concentration and is more susceptible to cracking and deformation.

[0050] In contrast, in the above embodiment, the pad 54 clamps the boundaries 13a, 13b, which include 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 is located in a region further from the boundaries 13a, 13b than the first regions 26a, 26b, with respect to the tailored blank 2, and does not sandwich the second region 27 of the first steel plate 21 and the second steel plates 22a, 22b that are adjacent to the first regions 26a, 26b.

[0052] With this process, the area over which the pad 54 grips the tailored blank 2 is smaller than when the pad 54 grips both the first region 26a, 26b and the second region 27, especially when the pad 54 grips the entire region of the tailored blank 2 where press forming is not required. As a result, the pressure exerted on the tailored blank 2 by the pad 54 (hereinafter referred to as the pressing pressure) increases as the pad 54 grips the tailored blank 2. When the pressing pressure is large, the movement of the first steel plate 21 and the second steel plates 22a, 22b in the tailored blank 2 is suppressed when press forming is performed, such as in the wall forming process S40, and the rate at which the thickness of the tailored blank 2 decreases due to press forming is reduced. In particular, deformation and cracking of the first steel plate 21 and the second steel plates 22a, 22b can be suppressed in the first region 26a, 26b, including the vicinity of the weld lines 14a, 14b. Therefore, it is possible to suppress unnecessary deformation of the tailored blank 2.

[0053] (1b) The pad 54 clamps both the first steel plate 21 and the second steel plates 22a and 22b during the clamping process S30 and the wall forming process S40. With this configuration, it is possible to suppress stress concentration on either the first steel plate 21 or the second steel plates 22a, 22b during press forming. Therefore, deformation and cracking of the tailored blank 2 can be suppressed more effectively than if the pad 54 were to clamp either the first steel plate 21 or the second steel plates 22a, 22b.

[0054] (1c) The first regions 26a and 26b where the pad 54 grips the tailored blank 2 are smaller than the second region 27 where the pad 54 does not grip the tailored blank 2. With this configuration, the area over which the pad 54 grips the tailored blank 2 can be further reduced, and the clamping pressure of the pad 54 can be further increased. As a result, unwanted deformation of the tailored blank 2 can be further suppressed.

[0055] (1d) In the above manufacturing method for press-formed product 1, a recess 15 is formed in the tailored blank 2 in the positioning step S10 and recess formation step S20, and then walls 122a and 122b are formed in the tailored blank 2 in the clamping step S30 and wall formation step S40.

[0056] In this process, recesses 15 are formed in the tailored blank 2 during the clamping process S30 and the wall forming process S40. Therefore, in the clamping process S30 and the wall forming process S40, the pad 54 only needs to clamp the first regions 26a and 26b of the tailored blank 2, where deformation and cracking are likely to occur, and does not need to clamp areas other than the first regions 26a and 26b. Consequently, the area over which the pad 54 clamps the tailored blank 2 can be reduced, and the clamping pressure of the pad 54 can be increased. Therefore, unnecessary deformation of the tailored blank 2 can be further suppressed.

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

[0059] (2a) In the above embodiment, the pad 54 sandwiches the vicinity of the boundaries 13a and 13b in the tailored blank 2 as the first regions 26a and 26b. However, the first regions 26a and 26b, in which the pad 54 sandwiches 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 any area other than the vicinity of the boundaries 13a and 13b in the tailored blank 2 as the second region 27. However, the areas where pad 54 does not grip tailored blank 2 are not limited to the examples above.

[0061] The pad 54 may be positioned so as not to pinch a portion of the region of the tailored blank 2 opposite to the side where deformation occurs due to press forming with respect to boundaries 13a and 13b, as a second region 27. For example, in the wall formation step S40, the pad 54 may be positioned so as not to pinch a portion of the region between boundary 13a and boundary 13b, as the region of the tailored blank 2 opposite to the side where wall portions 122a and 122b are formed by press forming with respect to boundaries 13a and 13b.

[0062] (2c) In the above embodiment, the first regions 26a and 26b in which the pad 54 grips the tailored blank 2 are smaller than the second region 27 in which the pad 54 does not grip the tailored blank 2. However, the area of ​​the first regions 26a and 26b gripped by the pad 54 may be greater than or equal to the area of ​​the second region 27. The pad 54 may grip at least the vicinity of the weld lines 14a and 14b in both the first steel plate 21 and the second steel plates 22a and 22b, with some areas other than the vicinity of the weld lines 14a and 14b not being gripped.

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

[0064] For example, as shown in Figure 6, if there is a step on the lower surface at 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 boundaries 13a, 13b.

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

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

[0067] With this configuration, even in a tailored blank 2 with a large difference in thickness between the two steel plates, the second punch 251b and pad 354 can grip the surfaces of both the first steel plate 21 and the second steel plates 22a and 22b. Therefore, cracks and deformation of the tailored blank 2 can be suppressed.

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

[0069] For example, the thickness and tensile strength of the first steel plate 21 and the second steel plates 22a and 22b may all be the same, and the tensile strength of the first steel plate 21 and the second steel plates 22a and 22b may all be 780 MPa or higher. In this case, the vicinity of the weld lines 14a and 14b is prone to softening due to the heat generated by welding, and stress tends to concentrate there. Therefore, by having the pad 54 clamp the vicinity of the weld lines 14a and 14b, it is possible to suppress the occurrence of cracks and deformation in the tailored blank 2.

[0070] For example, the thickness and tensile strength of the first steel plate 21 and the second steel plates 22a and 22b may all be the same, and both the first steel plate 21 and the second steel plates 22a and 22b may be made of stainless steel. In this case, the weld lines 14a and 14b of the tailored blank 2 are prone to fracture during the wall forming process S40. Therefore, by having the pad 54 clamp the area near the weld lines 14a and 14b, it is possible to suppress cracking and deformation of the tailored blank 2.

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

[0072] As an example, as shown in Figure 9, the first region 26a clamped by the pad 54 may be a part of the boundary 13a that includes a part of the weld line 14a in the first steel plate 21 and the second steel plate 22a. In Figure 9, the shaded area indicates the first region 26a clamped by the pad 54. The solid lines indicate the edges of the first steel plate 21 and the second steel plate 22a and the boundary 13a. The thick lines indicate the weld line 14a. The dashed lines indicate the edges of the press-formed product 1 after hypothetical press forming. The dashed lines indicate the parts where the wall portion 122a is formed during press forming.

[0073] With this configuration, the area over which the pad 54 grips the tailored blank 2 can be further reduced, and the clamping pressure of the pad 54 can be further increased. As a result, unwanted deformation of the tailored blank 2 can be further suppressed.

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

[0075] (2h) Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configuration of the above embodiment may be omitted. Furthermore, at least some of the configuration of the above embodiment may be added to or replaced with the configuration of other above embodiments.

[0076] [Technical Concept Disclosed in This Specified 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, The clamping structure is configured to hold the workpiece between the clamps, The aforementioned butt welding is a welding of the end face of the first steel plate and the end face of the second steel plate at the 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 in the workpiece, and not to clamp a second region of the first steel plate and the second steel plate that is further from the boundary than the first region and adjacent to the first region. Press forming machine.

[0077] [Item 2] The press forming apparatus described in item 1, The clamping structure clamps the workpiece along the boundary, Press forming machine.

[0078] [Item 3] A press forming apparatus as described in item 1 or item 2, The clamping structure is configured to clamp the end of the weld line, which is the butt-welded portion of the workpiece. Press forming machine.

[0079] [Item 4] A press forming apparatus described in any one of items 1 to 3, At least one of the thickness and strength of the first steel plate and the second steel plate differs from that of the first steel plate and the second steel plate. Press forming machine.

[0080] [Item 5] A press forming apparatus as described in item 4, The first steel plate and the second steel plate have different thicknesses from each other. The clamping structure has a step in the thickness direction of the first and second steel plates, corresponding to the difference in thickness between the first and second steel plates, so that it can clamp the surfaces of both the first and second steel plates. Press forming machine.

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

[0082] [Item 7] A method for manufacturing a press-formed product, in which a workpiece formed by pressing a first steel plate and a second steel plate joined by butt welding is formed, The aforementioned workpiece is clamped, Press-form at least one of the first steel plate and the second steel plate in the thickness direction, Includes, The aforementioned butt welding is a welding of the end face of the first steel plate and the end face of the second steel plate at the boundary between the first steel plate and the second steel plate. The clamping described above includes clamping a first region of the first steel plate and the second steel plate adjacent to the boundary as a specific region in the workpiece, and not clamping a second region of the first steel plate and the second steel plate that is further from the boundary than the first region and adjacent to the first region. A method for manufacturing press-formed products. [Explanation of symbols]

[0083] 1... Press-formed product, 2... Tailored blank, 5a, 5b... Press forming apparatus, 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 formation process.

Claims

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, The clamping structure is configured to hold the workpiece between the clamps, The aforementioned butt welding is a welding of the end face of the first steel plate and the end face of the second steel plate at the 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 in the workpiece, and not to clamp a second region of the first steel plate and the second steel plate that is further from the boundary than the first region and adjacent to the first region, and is configured to partially clamp the weld line and / or the boundary which is the butt-welded portion of the workpiece, and is configured to clamp the end of the weld line. Press forming machine.

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

3. A press molding apparatus according to claim 1, At least one of the thickness and strength of the first steel plate and the second steel plate differs from that of the first steel plate and the second steel plate. Press forming machine.

4. A press molding apparatus according to claim 3, The first steel plate and the second steel plate have different thicknesses. The clamping structure has a step in the thickness direction of the first and second steel plates, corresponding to the difference in thickness between the first and second steel plates, so that it can clamp the surfaces of both the first and second steel plates. Press forming machine.

5. A press forming apparatus according to any one of claims 1 to 4, The first region is smaller than the second region. Press forming machine.

6. A method for manufacturing a press-formed product, in which a workpiece formed by pressing a first steel plate and a second steel plate joined by butt welding is formed, The aforementioned workpiece is clamped, Press-form at least one of the first steel plate and the second steel plate in the thickness direction, Includes, The aforementioned butt welding is a welding of the end face of the first steel plate and the end face of the second steel plate at the 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 in the workpiece, and not clamping a second region of the first steel plate and the second steel plate that is further from the boundary than the first region and adjacent to the first region, and also includes partially clamping the weld line and / or the boundary which is the butt-welded portion of the workpiece, and clamping the end of the weld line. A method for manufacturing press-formed products.

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