Press forming blank, press forming part, and method for manufacturing a press forming part

Abstract

The present invention pertains to: a press forming blank (integrated blank) which is obtained by partially overlapping and integrating a plurality of partial blanks, and which is for a component in which two members having at least an upright wall part and a top plate part are connected so as to intersect; a press-formed component obtained by press-forming the integrated blank; and a method of producing the press-formed component.　As an example of an embodiment, provided is an integrated blank (press forming blank) in which: a first partial blank corresponding to a first member and a second partial blank corresponding to a second member are partially overlapped; at an overlapping part, a protrusion that is a portion of the first partial blank corresponding to a top plate part of the second member and a portion of the second partial blank corresponding to the top plate part are bonded; and a notch part is provided to a portion of the first partial blank corresponding to the upright wall part of the second member. Also provided are: a press-formed component obtained by press-forming the integrated blank; and a method of producing a press-formed component using the integrated blank.

Description

Technical Field

[0001] The present invention relates to a blank for press forming using a tailored blank, a press-formed part, and a method for manufacturing a press-formed part.

Background Art

[0002] There is a demand for reducing the life cycle GHG (total greenhouse gas emissions over the entire life cycle), mainly in automobiles and the like. An integrated technology that press-forms a plurality of connected parts / modules as one part (integrated part) at once for the purpose of increasing the efficiency of the manufacturing line by reducing the number of parts and omitting processes has attracted attention. Therefore, with the introduction of optimization design, the demand for manufacturing parts by press-forming a press-forming blank in which different types of steel plates are combined and integrated in a part, so-called tailored welded blanks (TWB), is increasing. Various press-forming technologies for TWB have been proposed since before (for example, Patent Document 1).

[0003] A press-forming blank (integrated blank) integrated with TWB is usually manufactured by butt-welding (linear welding) blanks (partial blanks) for each part made of steel plates of different thicknesses and types. Along with the increase in the size of the integrated blank, a method has been proposed in which two partial blanks are partially overlapped and the overlapping part is spot-welded to manufacture the integrated blank (Patent Documents 2 and 3). In the trend of increasing the size of parts / modules and the accompanying increase in the efficiency and cost reduction of part manufacturing, part manufacturing by batch press-forming of integrated blanks has been attracting more and more attention.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] When a single blank obtained by overlapping and joining two partial blanks (e.g., spot welding, overlap welding) is press-formed, cracks or other fractures may be observed in the overlapping portion of the partial blanks. If cracks or other fractures occur in a part, it is discarded because it cannot be distributed due to quality issues. In other words, fractures in press-formed products lead to a decrease in productivity.

[0006] In particular, when press-forming a part by TWB, in which a second member extending in a second direction intersecting the first direction is connected to a first member extending in a first direction, cracks may occur at the corner portion, which is the part where the blank is bent and deformed at the connection between the first and second members. In particular, when both the first and second members have cross-sections such as hat-shaped, U-shaped, or L-shaped, and have a top plate portion, vertical wall portion, or flange portion, cracks or wrinkles (hereinafter, cracks and wrinkles are collectively referred to as cracks) may occur at the part where the blank is bent and deformed at the connection between the first and second members (hereinafter, referred to as the corner portion) during press forming. For example, the corner portion corresponds to the part that is bent and deformed from the vertical wall portion of the first member to the vertical wall portion of the second member, especially the vicinity of the intersection of the top plate portion and vertical wall portion of the second member and the vertical wall portion of the first member, and the vicinity of the intersection of the vertical wall portion and flange portion of the first member and the vertical wall portion and flange portion of the second member.

[0007] In view of the above problems, the present invention relates to a press-formed blank for a part in which two members having at least a vertical wall portion and a top plate portion are connected so as to intersect, and aims to suppress cracking at the corner portion of the connection part of the members when press-forming an integrated blank formed by partially overlapping a plurality of partial blanks. [Means for solving the problem]

[0008] The inventors of this invention have diligently pursued development to achieve the above objectives and have obtained the following findings.

[0009] (a) This study investigated the cracking behavior that occurs at the connection point between two members when a part is manufactured in which a second member extending in a second direction intersecting the first direction is connected to a first member extending in a first direction, and both the first and second members have at least a top plate portion and a vertical wall portion, and when an integrated blank is formed by overlapping and joining a partial blank for the first member and a partial blank for the second member, the cracking behavior that occurs at the connection point between the two members was investigated.

[0010] As a result, it was confirmed that cracks occurred at the corner of the connection between the two members, specifically in the vertical wall and flange portions of both members. It is believed that when the partial blanks of both members were overlapped and welded, spot welding was performed across the entire overlapping area, which restricted the material flow in the vertical wall and flange portions of both members, resulting in large tensile strains and subsequent cracking. In other words, it is thought that one of the causes is the complex material flow behavior resulting from the bending and stretching of the vertical wall and flange portions of the first and second members in different directions during press forming.

[0011] On the other hand, it was confirmed that no cracks had occurred at the spot welds in the area corresponding to the top plate. This is thought to be because the top plate is less prone to distortion due to less material flow during press forming.

[0012] (b) Based on these findings, we conceived the idea that by joining the two blank sections only in the area corresponding to the top plate, where material flow is minimal, and not joining the two blank sections in the areas corresponding to the vertical walls and flanges, the two blank sections could deform freely, thus avoiding cracking. This led us to proceed with development.

[0013] (c) Furthermore, we found that in the vertical wall and flange portions of the joint between the first and second members, which exhibit complex material flow behavior, cracking caused by this complex material flow behavior can be suppressed by pre-cutting the complex material flow portion of one of the blanks and forming a notch. In particular, in the case of a part where the second member is connected to the first member by butting them together, the vertical wall portion of the first member undergoes complex deformation, so we found that it is beneficial to form a notch in the portion corresponding to the vertical wall portion of the first member.

[0014] This invention is based on the above findings, and its purpose is as follows.

[0015] [1] A press-formed blank for a part comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, and the portion in which the second member is connected so as to abut against the first member, The connected portion of the first member and the second member of the aforementioned component is formed by partially overlapping a first blank portion corresponding to the first member and a second blank portion corresponding to the second member. In the overlapping portion, which is the partially overlapped portion, The protruding portion of the first partial blank, which corresponds to the top plate portion of the second member, and at least a portion of the second partial blank, which corresponds to the top plate portion of the second member, are joined together. A press-formed blank characterized in that a notch is provided in the first partial blank between the protruding portion and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent. The component is typically a press-formed blank as described in [1], in which the second member is connected so as to abut against the vertical wall portion of the first member. [2] The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, The blank for press forming according to [1], having a protruding tongue piece in at least one of them. [3] The blank for press forming according to [1], wherein the first member and the second member further have a flange portion connected to the standing wall portion. [4] In the overlapping portion of the first partial blank, (a) the protruding portion, (b) the portion corresponding to the standing wall portion of the first member, (c) the portion corresponding to the flange portion of the first member The blank for press forming according to [3], having a protruding tongue piece in at least one of them. [5] The blank for press forming according to any one of [1] to [4], wherein the notch portion includes a portion corresponding to the ridge line that is the boundary between the top plate portion and the standing wall portion in the second member. That is, the first partial blank is the blank for press forming according to any one of [1] to [4], not including the portion corresponding to the ridge line of the second member. Preferably, the tip portion of the notch portion (the portion where the end of the protruding portion in the first partial blank and the end of the portion corresponding to the standing wall portion of the second member intersect) is not located at the portion corresponding to the ridge line of the second member. [6] In the first partial blank, the boundary line between the protruding portion and the portion corresponding to the standing wall Department of the first member is separated from the ridge line that is the boundary between the top plate portion and the standing wall portion of the first member. The blank for press forming according to any one of [1] to [5]. That is, the ridge line defining the boundary between the top plate portion and the standing wall portion of the first member exists continuously without being interrupted. [7] The blank for press forming according to any one of [1] to [6], wherein the part is a part for an automobile. [8] A component comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member is connected to the first member so as to abut against it, The portion of the component where the first member and the second member are connected is composed of an integrated blank formed by partially overlapping a first part blank corresponding to the first member and a second part blank corresponding to the second member. In the overlapping portion, which is the partially overlapped portion, At least the protruding portion of the first partial blank, which corresponds to the top plate portion of the second member, and the portion of the second partial blank, which corresponds to the top plate portion of the second member, are joined together. Furthermore, the part (press-formed part) is characterized in that a notch is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent. The aforementioned component is typically a component (press-formed component) in which the second member is connected so as to abut against the vertical wall portion of the first member. [9] The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, The part (press-formed part) according to [8], having a protruding tongue portion on at least one of them.

[10] The part (press-formed part) according to [8], wherein the first member and the second member further have flange portions that connect to the vertical wall portion.

[11] The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, (c) The portion of the first member corresponding to the flange portion The part (press-formed part) according to

[10] , having a protruding tongue portion on at least one of them.

[12] The notch portion includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member, and is a part (press-formed part) according to any one of the above [8] to

[11] . That is, the first partial blank is a part (press-formed part) according to any one of the items [8] to

[11] above, and does not include the portion corresponding to the ridge of the second member. Preferably, the tip of the notch (the point where the end of the protrusion in the first blank intersects with the end of the portion corresponding to the vertical wall of the second member) is not located on the portion corresponding to the ridge of the second member.

[13] In the first partial blank, the protruding portion and the vertical wall of the first member Department A part (press-formed part) according to any one of the above [8] to

[12] , wherein the boundary line with the part corresponding to and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated. In other words, the ridge line defining the boundary between the top plate portion and the vertical wall portion of the first member exists consistently without being interrupted.

[14] The part described in any one of the above [8] to

[13] (press-formed part), wherein the part is an automotive part.

[15] A method for manufacturing a part comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member is connected to the first member so as to abut against it, A first blank portion corresponding to the first member and a second blank portion corresponding to the second member are prepared. In the first partial blank, a protruding portion is formed which corresponds to the top plate portion of the second member of the first partial blank. A notch is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent. The First portion Blank and nearby 2 portion By partially overlapping the blanks, In the overlapping portion, which is the partially overlapped portion, At least the protruding portion of the first partial blank and at least a portion of the second partial blank that corresponds to the top plate portion of the second member are joined together to form an integrated blank, A method for manufacturing a part (press-formed part), characterized by press-forming the integrated blank and then further joining the overlapping portions to obtain a part (press-formed part). The aforementioned component is typically a component (press-formed component) in which the second member is connected so as to abut against the vertical wall portion of the first member.

[16] The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, At least one of them has a protruding tongue-shaped portion, A method for manufacturing a part (press-formed part) according to

[15] , wherein, after press forming, the tongue portion of the first partial blank and the vertical wall portion of the second member are joined together.

[17] A method for manufacturing a part (press-formed part) according to

[15] , wherein the first member and the second member further have flange portions that connect to the vertical wall portion.

[18] The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, (c) The portion of the first member corresponding to the flange portion At least one of them has a protruding tongue-shaped portion, A method for manufacturing a part (press-formed part) according to

[17] , wherein, after press forming, the tongue portion of the first partial blank and the vertical wall portion of the second member are joined together.

[19] A method for manufacturing a part (press-formed part) according to any one of the above

[15] to

[18] , wherein the notch portion includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member. In other words, the first partial blank does not include the portion corresponding to the ridge of the second member, and is a method for manufacturing a part (press-formed part) according to any one of the items

[15] to

[18] above. Preferably, the tip of the notch (the point where the end of the protrusion in the first blank intersects with the end of the portion corresponding to the vertical wall of the second member) is not located on the portion corresponding to the ridge of the second member.

[20] In the first partial blank, the protruding portion and the vertical wall of the first member Department A method for manufacturing a part (press-formed part) according to any one of the items

[15] to

[19] , wherein the boundary line with the part corresponding to and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated. In other words, the ridge line defining the boundary between the top plate portion and the vertical wall portion of the first member exists consistently without being interrupted. [twenty one] A method for manufacturing a part (press-formed part) according to any one of the above

[15] to

[20] , wherein the part is an automobile part. [Effects of the Invention]

[0016] According to the present invention, a press-formed blank for a part in which two members having at least a vertical wall portion and a top plate portion are connected so as to intersect is obtained, and when an integrated blank formed by partially overlapping multiple partial blanks is press-formed, it is possible to obtain a press-formed part in which cracks, particularly cracks at the corner portion of the connection between the two members, are suppressed. As a result, even large parts with complex shapes can be manufactured efficiently and productively. [Brief explanation of the drawing]

[0017] Since Figures 5 and 6 span multiple pages, Figure 5 is divided into Figure 5-1 and Figure 5-2, and these are collectively referred to as Figure 5. Similarly, Figure 6 is divided into Figure 6-1 and Figure 6-2, and these are collectively referred to as Figure 6. [Figure 1]Figure 1 is a schematic diagram showing an example of an L-shaped component with an L-shaped cross-section according to the present invention. Figure 1(a) is a schematic diagram of the case where there is no step between the first member and the second member, and Figure 1(b) is a schematic diagram of the case where there is a step. [Figure 2] Figure 2 is a schematic diagram showing an example of an L-shaped component with a flange and L-shaped cross section according to the present invention. Figure 2(a) is a schematic diagram of the case where there is no step between the first member and the second member, and Figure 2(b) is a schematic diagram of the case where there is a step. [Figure 3] Figure 3 is a schematic diagram showing an example of a T-shaped component with a C-shaped cross-section according to the present invention. Figure 3(a) is a schematic diagram of the case where there is no step between the first member and the second member, and Figure 3(b) is a schematic diagram of the case where there is a step. [Figure 4] Figure 4 is a schematic diagram showing an example of a T-shaped component with a hat-shaped cross-section according to the present invention. Figure 4(a) is a schematic diagram of the case where there is no step between the first member and the second member, and Figure 4(b) is a schematic diagram of the case where there is a step. [Figure 5] Figures 5(a) and 5(b) are schematic diagrams of the integrated blank according to the present invention, corresponding to the L-shaped component with an L-shaped cross-section in Figures 1(a) and 1(b), respectively. [Figure 6] Figures 6(a) and 6(b) are schematic diagrams of the integrated blank according to the present invention, corresponding to the L-shaped component with a flanged L-shaped cross section shown in Figures 2(a) and 2(b), respectively. [Figure 7] Figure 7 is a schematic diagram illustrating an integrated blank with tongue-shaped pieces, and is a schematic diagram of the overlapping portion of the integrated blank when tongue-shaped pieces are placed on the L-shaped component with a flanged L-shaped cross section shown in Figure 6(b). [Figure 8] Figure 8 shows an example where the intersection angle of an L-shaped component with an L-shaped cross-section is acute. Figure 8(a) is a schematic diagram of the external appearance, and Figure 8(b) is a schematic diagram of the integrated blank. [Figure 9] Figure 9 is a schematic diagram showing an example of a tubular cross-section T-shaped component formed by combining C-shaped cross-section T-shaped components shown in Figure 3(a). [Figure 10] Figure 10 is a schematic diagram showing an example of a T-shaped component with a tubular cross-section, which is formed by combining T-shaped components with a hat-shaped cross-section, as shown in Figure 4(a). [Figure 11]Figure 11(a) is a schematic diagram of the automotive part that served as the basis for the T-shaped part used in the embodiment, and Figure 11(b) is a schematic diagram of that T-shaped part. Figure 11(c) is a schematic diagram of the press-formed part according to the present invention manufactured in the embodiment. [Figure 12] Figure 12 is a schematic diagram of an integrated blank corresponding to the press-formed part in Figure 11(c). Note that when a figure contains (a), (b), etc., as in Figure 1(a)(b), these are collectively referred to as Figure 1, etc. [Modes for carrying out the invention]

[0018] The present invention will be described with reference to the drawings, with respect to one embodiment of the present invention (hereinafter simply referred to as the present invention).

[0019] Figures 1(a) and 1(b) (hereinafter, Figures 1(a) and 1(b) will be collectively referred to as Figure 1. Similarly, in Figures 2, 3, and 4, (a) and (b) of each figure will be collectively referred to as Figure 2, Figure 3, and Figure 4.) are schematic diagrams of an L-shaped component when viewed from above (hereinafter, the component will simply be referred to as an L-shaped component based on its shape when viewed from above), which is formed by connecting two L-shaped cross-section members, each having a top plate and a vertical wall. Figure 1(a) schematically shows the case where there is no step between the top plates of the first and second members, while Figure 1(b) schematically shows the case where there is a step between the top plates of the first and second members. As can be seen from Figure 1, the top plate and the vertical wall are connected in a direction perpendicular to the longitudinal direction (axial direction) of the members. The L-shaped component 5 shown in Figure 1 is an integrated component composed of a first member 1 and a second member 2. The first member 1 extends in a first direction 3, and the second member 2 extends in a second direction 4 intersecting the first direction 3, with the second member 2 connected to the first member 1 so as to abut against it. Typically, the second member 2 is connected so as to abut against the vertical wall portion 12 of the first member 1. Both the first member 1 and the second member 2 have an L-shaped cross-section and have top plate portions 11, 21 and vertical wall portions 12, 22 connected to the top plate portions, respectively. The L-shaped component 6 shown in Figure 2 is a configuration in which the first member 1 and the second member 2 of the L-shaped component 5 in Figure 1 further have flange portions 13, 23 connected to the opposite side of the top plate portions 11, 21 of the vertical wall portions 12, 22. Figure 2(a) schematically shows the case where there is no step between the top plate portions of the first member and the second member, and Figure 2(b) schematically shows the case where there is a step between the top plate portions of the first member and the second member. Figures 1(a) and 1(b) schematically show the press-formed parts obtained from the integrated blanks shown in Figures 5(a) and 5(b), respectively, while Figures 2(a) and 2(b) schematically show the press-formed parts obtained from the integrated blanks shown in Figures 6(a) and 6(b), respectively.

[0020] Based on the L-shaped parts 5 and 6 shown in Figures 1 and 2, various part shapes can be created. For example, as shown in Figure 3, a T-shaped part 7 can be created by connecting L-shaped parts 5 back to back. Figure 3(a) schematically shows the case where there is no step between the top plates of the first and second members, and Figure 3(b) shows the case where there is a step between the top plates of the first and second members. The first member 1 of the T-shaped part 7 shown in Figure 3 has a vertical wall on the opposite side from the second member 2, but this vertical wall can be formed by a simple bending press during press forming, so conventional press forming methods can be applied and there are no particular technical problems. Therefore, the T-shaped part 7 shown in Figure 3 can be made into a T-shaped part 7 with a C-shaped cross-section by combining it with the L-shaped part 5 with an L-shaped cross-section shown in Figure 1. Similarly, by connecting L-shaped parts 6 with bottom flanges shown in Figure 2 back to back, a T-shaped part 8 with a hat-shaped cross-section as shown in Figure 4 can be created. Figure 4(a) schematically shows the case where there is no step between the top plates of the first and second members, while Figure 4(b) schematically shows the case where there is a step between the top plates of the first and second members. Note that Figure 4(b) schematically shows a part formed by press molding of an integrated blank as shown in Figure 7.

[0021] Although not shown in the diagram, four L-shaped components from Figure 1 can be connected back-to-back on both the first and second members to form a cross-shaped component with a C-shaped cross section. Similarly, although not shown in the diagram, four L-shaped components from Figure 2 can be connected back-to-back to form a cross-shaped component with a hat-shaped cross section.

[0022] When these integrated parts are manufactured by press-forming an integrated blank, the material flow behavior becomes complex at the corners of the connection between the first and second members, particularly at the vertical walls and flanges of both members, resulting in large tensile strains and cracking. Therefore, since the problem of cracking at these corners is the same for cross-shaped, T-shaped, and L-shaped parts, the countermeasures considered for the L-shaped part shown in Figures 1 and 2 can be applied to various shapes of parts. Based on the above, the present invention will be explained below using the L-shaped part shown in Figures 1 and 2 (hereinafter referred to as "this part").

[0023] An integrated blank for press forming of this part was prepared. The integrated blank is a tailored blank (TWB) composed of a first partial blank corresponding to the first member and a second partial blank corresponding to the second member, which are partially overlapped. The first partial blank is the blank whose main part becomes the first member after press forming. Therefore, it is called the first partial blank corresponding to the first member. Similarly, the second partial blank is the blank whose main part becomes the second member after press forming, so it is called the second partial blank corresponding to the second member. When overlapping, the second partial blank is placed on top of the first partial blank so that the abutting member, i.e., the second member, abuts against the connection part of the first member. For example, Figures 5 and 6 correspond to Figures 1 and 2, respectively, with Figure 5 schematically showing the integrated blank in the case of an L-shaped cross section and Figure 6 schematically showing the integrated blank in the case of an L-shaped cross section with a flange. These integrated blanks are composed of a first partial blank 110 and a second partial blank 120. The first part blank 110 and the second part blank 120 are arranged such that the top plate portion 121, which corresponds to the top plate portion of the second member in the second part blank 120, overlaps with the portion of the first part blank that corresponds to the top plate portion of the second member. In Figures 5 to 7, the dashed lines indicate lines corresponding to the edges of the parts after press forming. For example, in the first part blank, it is the boundary line (edge ​​116) between the portion 111 corresponding to the top plate portion and the portion 112 corresponding to the vertical wall portion of the first member, and similarly in the second part blank, it shows the boundary line (edge ​​126) between the portion 121 corresponding to the top plate portion and the portion 122 corresponding to the vertical wall portion. The same applies to the figures showing other blanks.

[0024] Here, the portion of the second blank corresponding to the top plate of the second member refers to the portion of the second blank that corresponds to the top plate of the second member after press forming. Similarly, the portion of the first blank corresponding to the top plate of the second member refers to the portion of the first blank that corresponds to the top plate of the second member after press forming. Hereafter, similarly, the portion of the first blank that corresponds to the vertical wall of the second member after press forming will be referred to as the "portion of the first blank corresponding to the vertical wall of the second member." Note that the first blank and the second blank themselves may each be blanks made from a single steel plate, or they may be tailored blanks (TWB) made by joining the end faces of multiple steel plates together.

[0025] To integrate the two blank sections, the overlapping portion (overlapping portion 130) of the two blanks is joined. However, if the two blank sections 110 and 120 are joined across the entire overlapping portion 130, the material flow becomes complex in the vertical wall, flange, and corner portions of the part during press forming, resulting in large tensile strains in the material and making it prone to cracking. In particular, in the first blank section, the material flow becomes complex at the intersection of the portion corresponding to the top plate portion of the second member, the portion corresponding to the vertical wall portion of the second member, and the portion corresponding to the vertical wall portion of the first member, making it prone to cracking. On the other hand, in the first blank section 110, the portion corresponding to the top plate portion of the second member has less material flow and is less prone to cracking. Therefore, it is preferable to join only the portion of the overlapping portion 130 corresponding to the top plate portion of the second member to create an integrated blank.

[0026] By joining the overlapping portion 130 at least a portion of the top plate portion of the second member in this way, the two blank portions can exhibit deformation behavior as if they were separate blanks during press forming. In other words, cracking can be avoided by allowing both blank portions to deform freely.

[0027] The method of joining the two blanks is not particularly limited. For example, joining by welding, such as spot welding, lap welding, or lap fillet welding, is preferred. Spot welding is particularly preferred from the standpoint of workability. The type of welding is not particularly limited. Resistance welding, laser welding, etc., can be selected and decided as appropriate. For example, spot welding (resistance welding, laser spot welding) is preferred from the standpoint of applicability to complex shapes, workability, efficiency, and cost.

[0028] <Protrusion> Furthermore, it was found that it is preferable to separate only the portion of the overlapping portion 130 of the first blank 110 that corresponds to the top plate portion of the second member from the other portions to form the protruding portion 133. By doing so, material flow from the top plate portion of the first blank 1 to other portions (for example, the portion corresponding to the adjacent vertical wall portion) can be reduced or eliminated. In other words, the protruding portion 133 of the first blank 110 and at least a part of the top plate portion 121 of the second blank 120 are joined to form an integrated blank. As a result, after press molding, the protruding portion 133 overlaps with the top plate portion of the second member and becomes one.

[0029] The protrusion 133 of the first blank portion corresponds to the top plate portion of the second member after press forming. Therefore, the position of the protrusion 133 should be arranged according to how the second member 2 is butted against the first member 1. For example, it is preferable that the separation distance between the boundary line (the end on the base side of the protrusion) between the protrusion 133 of the first blank portion and the portion corresponding to the vertical wall portion of the first member and the ridge line 116 of the first member (the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member) is 0 mm or more. Preferably, the boundary line (the end on the base side of the protrusion) between the protrusion 133 of the first blank portion and the portion corresponding to the vertical wall portion of the first member and the ridge line 116 of the first member (the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member) is separated. That is, it is preferable that there is a step between the top plate portion of the first member and the top plate portion of the second member. The separation distance should be at least one, two, three, or five times the thickness of the second blank 120. This is because the separation between the end on the base side of the protrusion and the ridge line 116 of the first member ensures that the ridge line 116 of the first member is consistently present, thereby strengthening the resistance (buckling resistance) of the first member to external forces acting in the first direction.

[0030] The length of the protrusion (length in the second direction) is not particularly limited. From the viewpoint of joining the first and second blank portions at the overlapping portion, it is desirable to secure an area where joining is possible. For example, when joining by spot welding, it is preferable to secure an area of ​​at least twice the diameter of the spot weld. From this viewpoint, the length of the protrusion should be, for example, 20 mm or more, preferably 30 mm or more, or 40 mm or more. On the other hand, if the protrusion is too long, the first blank portion will take on an irregular shape in order to secure the protrusion, which will worsen the material yield when cutting from the raw material (steel plate). For this reason, it is preferable to make the length of the protrusion a length that matches the edge line of the original plate (steel plate) of the first blank portion. For example, it is preferable to make it less than or equal to the width of the vertical wall portion 112 of the first member of the first blank portion 110 (length in the second direction of the vertical wall portion), or the total width of the vertical wall portion and the flange portion (sum of the lengths in the second direction of the vertical wall portion and the flange portion).

[0031] The portion of the overlapping section 130 other than the protruding portion 133 becomes the portion of the first part blank that overlaps with the portion 122 corresponding to the vertical wall portion of the second part blank 120, or the portion of the first part blank that overlaps with the portions 122 and 123 corresponding to the vertical wall portion and flange portion of the second part blank 120 (hereinafter, in both cases, it will be referred to as the vertical wall overlapping section 135). The method of separating the protruding portion 133 and the vertical wall overlapping section 135 is not particularly limited. For example, a slit-shaped notch may be made between the protruding portion 133 and the vertical wall overlapping section 135. Alternatively, a notch may be formed by cutting off a portion of the part of the first part blank that corresponds to the vertical wall portion of the second member from the end of the protruding portion. The notch will be explained in detail below.

[0032] <Notch> Complex material flow occurs during press working at the vertical wall and flange portions of the connection between the first and second members (especially at the corners). Even if the overlapping portion of the first and second blanks is partially joined, this complex material flow causes large tensile strain, making it prone to cracking. Therefore, we have found that cracking caused by this complex material flow can be suppressed by pre-cutting and forming a notch in the portion where such complex material flow is likely to occur. As schematically shown in Figures 5 and 6, it is preferable to cut off a portion of the overlapping portion 130 of the first blank that overlaps with the portion 122 corresponding to the vertical wall of the second blank 120 to create a notch 134. In other words, the notch 134 is the portion where the first blank does not exist. This notch 134 separates the protruding portion 133 of the first blank 110 from the portion corresponding to the vertical wall of the second member. (In Figures 5 and 6, the notched portion 134 is the part enclosed by the thin dotted line.) Preferably, the notched portion is formed in the first blank portion by cutting out the entire portion corresponding to the vertical wall portion of the second member.

[0033] During press forming, material flow occurs in the bent portion. The more these bent portions intersect, the more complex the material flow becomes. Therefore, it is preferable that the notch 134 of the first blank portion be provided so as to include the portion corresponding to the ridge line 126 of the second member (the ridge line that forms the boundary between the top plate portion and the vertical wall portion). In other words, it is preferable that the first blank portion 110 does not include the portion corresponding to the ridge line 126 of the second member. By doing so, it is possible to suppress material flow in the first blank portion 110 during press forming due to the bending of the second member. Even more preferably, the tip portion of the notch 134 (the portion where the end of the protruding portion 133 in the first blank portion intersects with the end of the vertical wall overlap portion 135, or the portion that forms the end of the first blank portion connecting the end of the protruding portion and the end of the vertical wall overlap portion 135) is not located in the portion corresponding to the ridge line 126 of the second member. The tip of the notch 134 is where the most complex material flow occurs in the first blank, and by ensuring that it does not overlap with the ridge line 126, the complexity of the material flow is mitigated.

[0034] In particular, if the area of ​​the overlapping vertical wall portion 135 of the first blank becomes large, defects such as cracks and wrinkles are more likely to occur. This is because, even if the two blanks deform freely, a larger area of ​​the overlapping vertical wall portion 135 of the first blank makes it closer to the phenomenon of forming with a single blank, and complex material flow is more likely to occur. For this reason, it is desirable not to make the overlapping vertical wall portion 135 of the first blank unnecessarily large.

[0035] The area of ​​the overlapping vertical wall portion 135 of the first partial blank is preferably 90% or less of the area of ​​the overlapping portion between the first partial blank before the notch was cut off (the original first partial blank), the portion of the second partial blank corresponding to the vertical wall portion of the second member (hereinafter referred to as the vertical wall portion of the second partial blank), and the portion of the second partial blank corresponding to the flange portion of the second member (hereinafter referred to as the flange portion of the second partial blank) (i.e., the area of ​​the overlapping portion excluding the protruding portion). Preferably, it is 80% or less, 70% or less, 60% or less, 50% or less, or 40% or less. If the area of ​​the overlapping portion of the first partial blank is made too small, it will become impossible to join the parts after press working, so it is preferable to leave enough area to allow joining after press working. From this perspective, the area of ​​the overlapping portion 135 of the vertical wall of the first partial blank should be 5% or more, 10% or more, or 20% or more of the area of ​​the overlapping portion of the vertical wall portion and flange portion of the original first partial blank and the second partial blank.

[0036] The shape of the notch 134 is not particularly limited. For example, material flow behavior can be understood by simulations such as FEM (Finite Element Method), and parts that exceed a reference value (for example, the shear fracture strength of the steel plate used as the material) can be identified and those parts can be made into notches.

[0037] As an example, Figure 5 shows the case of an L-shaped cross section without a flange, and Figure 6 shows the case of an L-shaped cross section with a flange. In both Figures 5 and 6, the notch is cut along the protruding portion, and the overlapping vertical wall portion 135 of the first part blank corresponding to the vertical wall portion 122 of the second part blank has an arc-shaped edge. In Figure 6, in the portion corresponding to the flange portion 113 of the first part blank, the edge of the notch is straight. The shape of the notch 134 may be changed according to the vertical wall portion 112 and the flange portion 113 of the first part blank.

[0038] <tongue part> One or more tongue-shaped protrusions (tongue portions) protruding from the first part blank may be provided in the region of the notch 134 in the overlapping portion 130 of the first part blank. That is, one or more protruding tongue portions may be provided on the first part blank. Since the region of the notch originally corresponds to the vertical wall portion of the second member, these tongue portions are formed to conform to the inner surface of the vertical wall portion of the second member after press forming. Therefore, by joining the tongue portion of the first part blank and the vertical wall portion of the second part blank after press forming, the rigidity and collision characteristics of the integrated part can be improved. In addition, as a secondary effect, by providing the tongue portions, the material cut off in the notch can be effectively utilized. Furthermore, by bending the tongue portions during press forming, displacement of the second part blank during forming can be prevented.

[0039] The placement of the tongue portion is not particularly limited as long as it is within the area of ​​the notch 134 of the first portion blank. As an example, Figure 7 shows the overlapping portion of the first portion blank and the second portion blank when the tongue portion is placed on the integrated blank of the flanged L-shaped cross section part shown in Figure 6(b). In the example in Figure 7, the first portion blank 110 has three protruding tongue portions in the overlapping portion 130: (a) a tongue portion 136 provided on the protruding portion 133 of the first portion blank, (b) a tongue portion 137 provided on the portion corresponding to the vertical wall portion 112 of the first portion blank, and (c) a tongue portion 138 provided on the portion corresponding to the flange portion 113 of the first portion blank. However, it is preferable to have a protruding tongue portion in at least one of these locations. In the case of the first member with an L-shaped cross section without a flange, although not shown in the illustration, it is preferable that at least one of (a) the protruding portion of the first blank and (b) the portion corresponding to the vertical wall of the first blank have a protruding tongue portion at the overlapping portion of the first blank. Since these tongue portions are separated from each other, each tongue portion is simply bent independently during press forming, so no defects such as cracking occur.

[0040] There is no particular limit to the number of tongue-shaped parts. In the example in Figure 7, tongue-shaped parts are provided in three locations, but it is not necessary to provide all of these parts; at least one of them can be provided as needed. Of course, multiple tongue-shaped parts can be provided in each of (a) to (c). When providing multiple tongue-shaped parts, it is desirable to arrange them so that they do not interfere with each other after press forming. This is because mutual interference can cause defects such as wrinkles during press forming.

[0041] The size of the tongue portion is not particularly limited. As mentioned above, after press forming, the tongue portion of the first part blank is formed to conform to the inner surface of the vertical wall portion of the second member, and the rigidity of the integrated part can be increased by joining the vertical wall portion of the second part blank and the tongue portion of the first part blank after press forming. For this reason, it is desirable to ensure that the tongue portion has enough area to allow joining. For example, when joining by spot welding, it is desirable that the length and width of the tongue portion be at least twice the diameter of the spot weld (the length of the tongue portion is the maximum length of the tongue portion in the direction protruding from the first part blank (the length direction of the tongue portion), and the width of the tongue portion is the maximum length of the tongue portion in the direction perpendicular to the length direction of the tongue portion). The length and width of the tongue portion should be, for example, 10 mm or more, preferably 20 mm or more, or 30 mm or more. The upper limits of the length and width of the tongue portion should preferably be determined appropriately according to the shape of the first part blank before the notch portion is cut out. Making the shape of the first blank irregular in order to secure the tongue portion would not only worsen the material yield but also potentially lead to increased blank processing costs.

[0042] <Intersection angle between the first and second members> The intersection angle of the first and second members, i.e., the intersection angle of the first direction and the second direction, is not particularly limited. Figure 8 shows a schematic diagram of an L-shaped part when the intersection angle of the first member 1 and the second member 2, i.e., the intersection angle of the first direction 3 and the second direction 4, is θ. Figure 8(a) is an external view of the L-shaped part 5, and Figure 8(b) shows a schematic diagram of its integrated blank. In Figure 8, the intersection angle θ is shown as an acute angle (90° or less), but it can also be an obtuse angle. The lower limit of the intersection angle θ is not particularly limited as long as it is greater than 0°, but it should be set appropriately depending on the processing accuracy of the press forming. Similarly, the upper limit of the intersection angle θ is not particularly limited as long as it is less than 180°. For example, when integrating corresponding L-shaped parts that are back-to-back as shown in Figures 3 and 4, if the intersection angle on this side is acute, the intersection angle of the member on the opposite side will also be acute, and this will be set appropriately depending on the processing accuracy of the press forming. Figure 8(a) corresponds to Figure 1(a), and Figure 8(b) corresponds to Figure 5(a), showing L-shaped components with an L-shaped cross-section without a flange. For example, in the case of an L-shaped cross-section with a flange, Figure 8(a) should be modified to correspond to Figure 2(a), and Figure 8(b) should be modified to correspond to Figure 6(a).

[0043] The above describes a press-formed blank for a part having a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, and the second member having a portion connected to the first member so as to abut against it. That is, the press-formed blank according to the present invention is a blank that includes a blank in which the first portion blank and the second portion blank of the connected part are integrated. There may be one or more of these integrated blanks of the connected part in the press-formed blank for the entire part, and their arrangement (position in the press-formed blank for the entire part) is not limited.

[0044] Furthermore, the method of joining blanks other than the portion where the first and second members are connected is not particularly limited in the press-formed blank for the entire part. A tailored blank (TWB) may be formed by joining the end faces of partial blanks together.

[0045] <Press-formed parts> The part obtained by integrally press-forming an integrated blank composed of the first and second blanks described above is an integrated part (press-formed part). As described above, the L-shaped part with an L-shaped cross section shown in Figures 1 and 2 is the basic form, and by combining them, the T-shaped part shown in Figures 3 and 4 can be obtained. By further combining them, a cross-shaped part can also be obtained, although it is not shown. Similarly, a shape that combines L-shapes, T-shapes, and crosses, such as a grid-like part, can also be obtained as an integrated part by press-forming an integrated blank obtained by combining the L-shaped parts shown in Figures 1 and 2.

[0046] Furthermore, by stacking these integrated parts vertically, with one part flipped over, a part with a tubular cross-section can also be obtained. For example, by combining and joining the T-shaped part 7 in Figure 3(a) vertically, a T-shaped part with a hexagonal cross-section as shown in Figure 9 can be obtained. Similarly, by combining and joining the hat-shaped T-shaped part 8 in Figure 4(a) vertically, a T-shaped part with a flange and a hexagonal cross-section can be obtained as shown in Figure 10.

[0047] These parts can also be manufactured using the molded blank according to the present invention. That is, a component comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member is connected to the first member so as to abut against it, The portion of the component where the first member and the second member are connected is composed of an integrated blank formed by partially overlapping a first part blank corresponding to the first member and a second part blank corresponding to the second member. In the overlapping portion, which is the partially overlapped portion, At least the protruding portion of the first partial blank, which corresponds to the top plate portion of the second member, and the portion of the second partial blank, which corresponds to the top plate portion of the second member, are joined together. Furthermore, a notch is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent. as needed The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, (c) The portion of the first member corresponding to the flange portion It is a part (press-formed part) having a protruding tongue-shaped portion on at least one of its parts.

[0048] Furthermore, the aforementioned component is typically a component (press-formed component) in which the second member is connected so as to abut against the vertical wall portion of the first member.

[0049] The notch portion is a part (press-formed part) that includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member. That is, the first partial blank is a part (press-formed part) that does not include the portion of the second member corresponding to the ridge line. Preferably, the tip portion of the notch portion (the portion where the end of the protrusion in the first partial blank intersects with the end of the portion corresponding to the vertical wall portion of the second member) is not located in the portion of the second member corresponding to the ridge line.

[0050] Furthermore, in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated. In other words, the ridge line that defines the boundary between the top plate portion and the vertical wall portion of the first member exists consistently without being interrupted.

[0051] In conventional methods, the first and second components are press-formed separately and then joined together. Therefore, it has been confirmed that this method achieves extremely high efficiency in terms of processability. In particular, in the case of a component made by combining multiple L-shaped parts, the effect is extremely significant because what was previously obtained by press-forming the individual components and then welding them together can now be obtained as a single integrated component through integrated press-forming.

[0052] Furthermore, the component (press-formed component) according to the present invention allows for a smaller radius of curvature at the corner formed by the first and second components. This is because complex material flow behavior is suppressed in the first partial blank, making it less likely for cracks to occur even when the radius of curvature at the corner is reduced. In conventional press forming with tailored blanks (TWB), the radius of curvature at the corner of the first and second components was approximately 120 mm, but when the present invention is applied, no cracks occurred even with a radius of curvature of 15 mm. For example, in the case of structural components for automobiles, a smaller radius of curvature at the corner increases the mounting capacity for components.

[0053] The applications of the parts according to the present invention are not particularly limited. For example, they can be applied to automotive parts. Examples of automotive parts include components of the front module (e.g., front side members and cross members), side sills (rockers) and floor cross members, floor tunnels and floor cross members, and components of the rear under module (e.g., rear side members and cross members). When applied to automotive parts, improvements in ease of entry and exit can also be expected. The parts referred to here include parts to which the aforementioned integrated blank has been applied.

[0054] <Method of manufacturing parts> In the method for manufacturing parts according to the present invention, known methods such as press forming methods and joining methods (for example, welding methods such as spot welding, lap welding, and lap fillet welding) can be applied, other than manufacturing the integrated blank described above. To reiterate, the method for manufacturing parts according to the present invention is as follows.

[0055] Prepare a first blank portion corresponding to the first member and a second blank portion corresponding to the second member. In the first partial blank, a protruding portion is formed which corresponds to the top plate portion of the second member of the first partial blank. In the first partial blank, a notch without the first partial blank is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member. (At this point, it is advisable to remove the portion corresponding to the notch in the first blank section. Furthermore, if necessary, remove the portion to form the tongue section.) · 1 portion Blank and 2 portion By partially overlapping the blanks, • In the overlapping portion, which is the partially overlapped part, At least the protruding portion of the first blank and at least a portion of the second blank that corresponds to the top plate portion of the second member are joined together to form an integrated blank. The formed integrated blank is press-molded, and then the parts that are not joined at the overlapping sections are further joined to obtain a part (press-molded part). Furthermore, if a protruding tongue-shaped portion is provided on the first blank portion as needed, it is advisable to join the first member (the tongue-shaped portion of the first blank portion) and the second member (the second blank portion) at the portion corresponding to the tongue-shaped portion after press molding.

[0056] Furthermore, as mentioned above, in the overlapping portion, the first partial blank (a) The protruding portion, (b) The portion corresponding to the vertical wall portion of the first member, (c) The portion of the first member corresponding to the flange portion It is preferable to provide a protruding tongue-shaped portion on at least one of them.

[0057] The aforementioned component is typically a component (press-formed component) in which the second member is connected so as to abut against the vertical wall portion of the first member.

[0058] Furthermore, the notch portion is a manufacturing method for a part (press-formed part) that includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member. In other words, the first partial blank is a manufacturing method for a part (press-formed part) that does not include a portion corresponding to the ridge line of the second member. Preferably, the tip portion of the notch portion (the portion where the end of the protrusion in the first partial blank intersects with the end of the portion corresponding to the vertical wall portion of the second member) is not located in the portion corresponding to the ridge line of the second member.

[0059] Furthermore, in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated. In other words, the ridge line that defines the boundary between the top plate portion and the vertical wall portion of the first member exists consistently without being interrupted. The parts referred to here are also included in the parts (press-formed parts) according to the present invention as described above. Therefore, the applications of the parts according to the present invention are not particularly limited. For example, they can be applied to automotive parts.

[0060] The press forming method is not particularly limited. Existing press forming methods can be applied. For example, it does not matter whether it is cold forming or hot forming. In the case of hot forming, so-called hot stamping may be applied. Here, hot stamping is a method in which the material is heated in a heating furnace or the like and then press-formed at a high temperature. Because the temperature is high, it softens compared to room temperature, so the forming load is reduced. Also, in the case of steel plates, a high-strength formed product can be obtained by heating it to the austenite region and then hardening it at the bottom dead center of the press. Conventional hot stamping methods can be applied.

[0061] The method of joining the unjoined portion of the overlapping section between the first and second blanks after press forming (including the joining of the tongue portion of the first blank with the second blank) is not particularly limited. For example, joining by welding such as spot welding, overlap welding, or overlap fillet welding is preferred. Spot welding is particularly preferred from the viewpoint of workability. The type of welding is not particularly limited. Resistance welding, laser welding, etc., can be appropriately selected and determined. For example, spot welding (resistance welding, laser spot welding) is preferred from the viewpoint of applicability to complex shapes, workability, efficiency, and cost.

[0062] By joining the unjoined portions of the overlapping section between the first and second blanks after press forming (including the joint between the tongue portion of the first blank and the second blank), the joint strength between the first and second members is increased, further improving rigidity and impact characteristics. [Examples]

[0063] [Example 1] A part modeled after a hat-shaped cross-section T-shaped component (Figure 11(b): a component where a cross member abuts against the vertical wall of a side member), which is part of the rear under module of an automobile shown in Figure 11(a), was press-formed. The part specifications are as follows.

[0064] (1) Side member (first member): Hat-shaped cross section • Tabletop width: 86mm • Vertical wall section length: 86mm • Flange width: 40mm • Plate thickness: 2.0 mm • Tensile strength: 1180 MPa

[0065] (2) Cross member (second member): Hat-shaped cross section • Tabletop width: 86mm • Vertical wall section length: 67mm • Flange width: 40mm • Plate thickness: 1.0 mm • Tensile strength: 1180 MPa

[0066] (3) Parts specifications • Intersection angle between side members and cross members: 90° (4) Press forming (cold working) • Hydraulic press molding machine

[0067] The following blanks were prepared for press forming. Four blanks were prepared for each sample. [Sample 1] Comparative example: Blank without overlapping section (conventional tailored blank (TWB) formed by butting the end faces of partial blanks together)

[0068] [Sample 2] Comparative example: The first and second blanks are partially overlapped, and the first portion A blank without notches (i.e., no protrusions), and a single, integrated blank with spot welding across the entire overlapping surface.

[0069] [Sample 3] Embodiment according to the present invention: A first partial blank and a second partial blank are partially overlapped, and at the overlapping portion, a protruding portion corresponding to the top plate portion of the second member of the first partial blank and a portion corresponding to the top plate portion of the second partial blank are spot welded together, a notch is provided in the portion corresponding to the vertical wall portion of the second member of the first partial blank, and a tongue portion is provided in the portion corresponding to the protruding portion and the flange portion of the first member to form an integrated blank. (The part after press forming corresponds to the part in Figure 11(c). Figure 12 shows a schematic diagram of the integrated blank corresponding to the press-formed part in Figure 11(c). In Figures 11 and 12, the white circles on the top plate portion of the second member represent the integrated blank.) This is a schematic representation of the spot welding locations.

[0070] [Sample 4] Example according to the present invention: An integrated blank without tongue portions in Sample 3. That is, in Figure 12, the tongue portions 136 and 138 of the first partial blank 110 are absent, a notch is provided in the portion corresponding to the vertical wall portion of the second member of the first partial blank, and the protruding portion of the first partial blank and the portion corresponding to the top plate portion of the second partial blank are spot welded to form an integrated blank.

[0071] Three pieces each of samples 1-4 were press-formed under the same pressing conditions, and the occurrence of cracks was visually inspected, focusing on the vicinity of the connection between the first and second components, where cracking is more likely to occur. The results are shown below. No cracks were found in the second blank of any of the samples. [Sample 1] Cracks found in the flange portion of the first blank (4 out of 4 pieces) [Sample 2] Cracks were found in the flange portion of the first blank (4 out of 4 pieces), and in 3 of these pieces, the cracks had progressed to the vertical wall portion. [Sample 3] No cracks were observed in either the flange or vertical wall portion of the first blank. A schematic diagram of the press-formed part of Sample 3 is shown in Figure 11(c). [Sample 4] No cracks were observed in either the flange or vertical wall portion of the first blank section. The schematic diagram of the press-formed part of Sample 4 is the same as the press-formed part in Figure 11(c), but without the tongue portions 136 and 138.

[0072] [Example 2] Next, the parts were tested using hot stamping. The part shapes were the same as in Example 1. The tensile strength and press forming method for each part after mold hardening (after hot stamping) are as follows.

[0073] (1) Side member (first member) • Tensile strength after mold hardening: 1500 MPa (2) Cross member (second member) • Tensile strength after mold hardening: 1500 MPa (4) Press forming (hot stamping forming) • Hydraulic press molding machine The material was heated in a furnace at 900°C for 5 minutes, then transferred to a mold in a press machine with a transfer time of 15 seconds for hot stamping. After holding at the bottom dead center for 30 seconds to harden the mold, it was removed.

[0074] For press forming, four blanks of each sample (1-4) were prepared, similar to Example 1. All four blanks of samples 1-4 were press-formed under the same pressing conditions, and the crack formation was visually inspected, similar to Example 1. The results are shown below. [Sample 1] Cracks found in the flange portion of the first blank (4 out of 4 pieces) [Sample 2] Cracks were found in the flange portion of the first blank (4 out of 4 pieces), and in two of these pieces, the cracks had progressed into the vertical wall portion. [Sample 3] No cracks were observed in either the flange or vertical wall portion of the first blank. The press-formed part of Sample 3 had the same shape as that of Example 1, and a schematic diagram of it is shown in Figure 11(c). [Sample 4] No cracks were observed in either the flange or vertical wall portion of the first blank. The press-formed part of Sample 4 also had the same shape as that of Example 1. Its schematic diagram is the same as the press-formed part in Figure 11(c), but without the tongue portions 136 and 138.

[0075] [Example 3] Next, we simulated the manufacturing of the same parts using the same samples (samples 1-4) as in Example 2 by hot stamping, and verified the rate of plate thickness reduction. The simulation was performed using CAE (Autoform R10). The maximum plate thickness reduction rate and its location are shown below. In all cases, the location where the maximum plate thickness reduction rate occurred was near the connection between the first and second members, where cracks are likely to occur. Furthermore, the locations where the maximum plate thickness reduction rate occurred for samples 1 and 2 coincided with the locations where cracks occurred in Example 2. [Sample 1] 38% (Flange portion of the first blank) [Sample 2] 27% (Flange portion of the first blank) [Sample 3] 19% (Vertical wall portion of the first blank) [Sample 4] 19% (Vertical wall portion of the first blank) Since the likelihood of cracking increases when the plate thickness reduction rate exceeds 25%, it can be seen that in samples 3 and 4 according to the present invention, the plate thickness reduction rate was suppressed and cracking was avoided.

[0076] From the above, it was confirmed that cracking is suppressed in integral press forming by using the press forming blank according to the present invention. [Industrial applicability]

[0077] This invention can be widely used in a wide range of industrial fields, including the transportation machinery industry (such as automobiles), the general machinery industry, and electrical equipment. [Explanation of symbols]

[0078] 1. First member 2. Second Member 3. First direction 4. Second direction 5 L-shaped parts (L-shaped cross section) 6. L-shaped component (L-shaped cross section with flange) 7 T-shaped part (C-shaped cross section) 8. T-shaped component (hat-shaped cross-section) 11. Top plate portion of the first component (top plate section of the first component) 12. The portion of the first member corresponding to the vertical wall (the vertical wall portion of the first member) 13. Flange-equivalent portion of the first member (flange portion of the first member) 21. Top plate portion of the second component (top plate section of the second component) 22. Vertical wall portion of the second member (vertical wall section of the second member) 23. Flange-equivalent portion of the second member (flange portion of the second member) 110 Part 1 Blank 111 The top panel equivalent portion of the first blank section (top panel part of the first blank section) 112 Vertical wall portion of the first blank section (Vertical wall section of the first blank section) 113 Flange equivalent portion of the first blank (flange section of the first blank) 116. Ridge of the first blank section (boundary between the top plate and the vertical wall section) 117. Ridge of the first blank section (boundary between the vertical wall section and the flange section) 120 Part 2 Blank 121 Part equivalent to the top panel of the second blank section (Top panel section of the second blank section) 122 Vertical wall portion of the second blank section (Vertical wall section of the second blank section) 123 Flange equivalent portion of the second blank (flange section of the second blank) 126. The ridge line of the second blank section (boundary between the top plate and the vertical wall section) 127. Ridge of the second blank section (boundary between the vertical wall section and the flange section) 130 Overlapping section 133 Protrusion 134 Notch 135 Overlapping sections of vertical walls 136 tongue piece 137 Tongue piece 138 Tongue piece

Claims

1. A press-formed blank for a part, comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member has a portion connected so as to abut against the vertical wall portion of the first member, The connected portion of the first member and the second member of the component is formed by partially overlapping a first blank corresponding to the first member and a second blank corresponding to the second member. In the overlapping portion, which is the partially overlapped portion, The protruding portion of the first partial blank, which corresponds to the top plate portion of the second member, and at least a portion of the second partial blank, which corresponds to the top plate portion of the second member, are joined together. A press-formed blank characterized in that a notch is provided in the first partial blank between the protruding portion and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent.

2. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, The press-formed blank according to claim 1, wherein at least one of the blanks has a protruding tongue-shaped portion.

3. The press-formed blank according to claim 1, wherein the first member and the second member further have flange portions that connect to the vertical wall portion.

4. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, (c) The portion of the first member corresponding to the flange portion The press-formed blank according to claim 3, wherein at least one of the blanks has a protruding tongue-shaped portion.

5. The press-formed blank according to any one of claims 1 to 4, wherein the notched portion includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member.

6. The press-formed blank according to any one of claims 1 to 4, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

7. The press-formed blank according to claim 5, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

8. The press-formed blank according to any one of claims 1 to 4, wherein the aforementioned component is an automotive part.

9. A press-formed part comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member is connected to the vertical wall portion of the first member so as to abut against it, The portion of the press-formed part where the first member and the second member are connected is composed of an integrated blank formed by partially overlapping a first blank corresponding to the first member and a second blank corresponding to the second member. In the overlapping portion, which is the partially overlapped portion, At least the protruding portion of the first partial blank, which corresponds to the top plate portion of the second member, and the portion of the second partial blank, which corresponds to the top plate portion of the second member, are joined together. Furthermore, the press-formed part is characterized in that a notch is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent.

10. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, The press-formed part according to claim 9, having a protruding tongue-shaped portion on at least one of them.

11. The press-formed part according to claim 9, wherein the first member and the second member further have flange portions that connect to the vertical wall portion.

12. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, (c) The portion of the first member corresponding to the flange portion The press-formed part according to claim 11, wherein at least one of the parts has a protruding tongue-shaped portion.

13. The press-formed part according to any one of claims 9 to 12, wherein the notch portion includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member.

14. The press-formed part according to any one of claims 9 to 12, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

15. The press-formed part according to claim 13, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

16. The press-formed part according to any one of claims 9 to 12, wherein the press-formed part is an automobile part.

17. A method for manufacturing a press-formed part comprising a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, each having a top plate portion and at least one vertical wall portion connected to the top plate portion, wherein the second member is connected so as to abut against the vertical wall portion of the first member, A first blank portion corresponding to the first member and a second blank portion corresponding to the second member are prepared. In the first partial blank, a protruding portion is formed which corresponds to the top plate portion of the second member of the first partial blank. A notch is provided between the protruding portion of the first partial blank and the portion corresponding to the vertical wall portion of the second member, where the first partial blank is absent. The first partial blank and the second partial blank are partially overlapped, In the overlapping portion, which is the partially overlapped portion, At least the protruding portion of the first partial blank and at least a portion of the second partial blank that corresponds to the top plate portion of the second member are joined together to form an integrated blank, A method for manufacturing a press-formed part, characterized by press-forming the integrated blank and then further joining the overlapping portions to obtain a press-formed part.

18. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, At least one of them has a protruding tongue-shaped portion, The method for manufacturing a press-formed part according to claim 17, wherein the tongue portion of the first partial blank and the vertical wall portion of the second member are joined after the press forming.

19. The method for manufacturing a press-formed part according to claim 17, wherein the first member and the second member further have flange portions that connect to the vertical wall portion.

20. The first partial blank, in the overlapping portion, (a) The protruding portion, (b) The portion of the first member corresponding to the vertical wall portion, (c) The portion of the first member corresponding to the flange portion At least one of them has a protruding tongue-shaped portion, The method for manufacturing a press-formed part according to claim 19, wherein the tongue portion of the first partial blank and the vertical wall portion of the second member are joined after the press forming.

21. The method for manufacturing a press-formed part according to any one of claims 17 to 20, wherein the notched portion includes a portion corresponding to the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the second member.

22. A method for manufacturing a press-formed part according to any one of claims 17 to 20, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

23. The method for manufacturing a press-formed part according to claim 21, wherein in the first partial blank, the boundary line between the protruding portion and the portion corresponding to the vertical wall portion of the first member and the ridge line that forms the boundary between the top plate portion and the vertical wall portion of the first member are separated.

24. A method for manufacturing a press-formed part according to any one of claims 17 to 20, wherein the press-formed part is an automobile part.

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