Blank for press molding, press-molded component, and method for manufacturing press-molded component

Abstract

A blank for press molding disclosed herein is a blank for press molding a component having a portion connected such that a second member (2) butts against a first member (1). The blank for press molding is formed by partially overlapping a first partial blank (110) corresponding to the first member (1) and a second partial blank (120) corresponding to the second member (2). The first member (1) and the second member (2) each have a top plate part (11, 21) and a standing wall part (12, 22). The first partial blank (110) has an opening (116) and a boss protrusion (115) at an end thereof along the opening (116). The second partial blank (120) has a flange protrusion (125) at the end thereof. At an overlapping part (130) that is a partially overlapped part, the boss protrusion (115) of the first partial blank (110) and a part (121) corresponding to the top plate part of the second member of the second partial blank are joined to each other, and / or a part (112) corresponding to the standing wall part of the first member of the first partial blank and the part (121) corresponding to the top plate part of the second member of the flange protrusion (125) of the second partial blank (120) are joined to each other.

Description

Press-molding blank, press-molded part, and method for manufacturing press-molded part

[0001] The present disclosure relates to a blank for press molding using a tailored blank, a press-molded part, and a method for manufacturing a press-molded part.

[0002] There is a demand for reducing lifecycle GHG (total greenhouse gas emissions over the entire lifecycle), particularly in automobiles. With the aim of improving the efficiency of production lines by reducing the number of parts and omitting processes, integration technologies that press-form multiple connected parts or modules into a single part (integrated part) in one go have been attracting attention. Therefore, with the introduction of optimized design, there is an increasing demand for parts to be manufactured by press-forming so-called tailored welded blanks (TWBs), which are press-formable blanks formed by combining and integrating different types of steel sheets within a part. Various TWB press-forming technologies have been proposed in the past (for example, see Patent Document 1).

[0003] A press-molding blank (integrated blank) integrated by TWB is usually manufactured by butt-joining and laser-welding (line welding) separate blanks (partial blanks) made of steel sheets of different thicknesses and types. To reduce the welding cost of integrated blanks, a method has been proposed for manufacturing an integrated blank by partially overlapping two partial blanks and spot-welding the overlapping portion (Patent Documents 2 and 3). With the increasing size of parts and modules and the accompanying trend toward more efficient and cost-effective part manufacturing, part manufacturing by batch press-molding of integrated blanks is attracting increasing attention.

[0004] International Publication No. 2020 / 059804 International Publication No. 2020 / 002335 International Publication No. 2022 / 097058

[0005] When two partial blanks are overlapped and joined (for example, by spot welding or lap welding) to form an integrated blank, the strength of the part may be reduced at the overlapping portion of the partial blanks. This reduction in strength can lead to problems not only in design but also in productivity, as crack resistance and deformation resistance against the design load cannot be ensured.

[0006] In particular, when a part is obtained by press-molding an integrated blank, such as the side members and cross members of an automobile's lower structural members, in which a first member (side member) extending in a first direction is connected to a second member (cross member) extending in a second direction that intersects the first direction so that they butt against each other, this can lead to the problem that the expected reaction force (proof strength) cannot be obtained against an impact force in the axial direction of the first member (the longitudinal direction of the member (the first direction in the case of the first member)).

[0007] In view of the above problems, the present disclosure aims to provide an improvement in terms of the strength of the connection between two members having at least a vertical wall portion and a top plate portion in a part that is connected so that the two members intersect, and to provide a press-molded blank for such a part, a press-molded part, and a method for manufacturing the press-molded part.

[0008] The present inventors have made extensive development efforts to achieve the above object and have obtained the following findings.

[0009] (a) In manufacturing a component in which a first member extending in a first direction and a second member extending in a second direction intersecting the first direction, both the first member and the second member having at least a top plate portion, a vertical wall portion, and a flange portion, and the second member is connected to the first member so as to abut against the first member, a press-molded part was manufactured by press-molding an integrated blank obtained by overlapping and joining a partial blank corresponding to the first member (a partial blank the majority of which will become the first member) and a partial blank corresponding to the second member (a partial blank the majority of which will become the second member).The reaction force (proof stress) of the manufactured press-molded part against an impact load in the axial direction (first direction) of the first member was investigated.

[0010] As a result, it was discovered that in the press forming of a single blank such as a conventional tailored blank (TWB) made by butt-joining partial blanks, or an integrated blank made of partially overlapping TWBs, the ridgeline between the top plate portion and the vertical wall portion of the first member (hereinafter sometimes simply referred to as the ridgeline of the first member) at the connection portion between the first member and the second member (hereinafter sometimes simply referred to as the connection portion) is severed, preventing smooth transmission of impact loads and making the load path unstable. As a result, it is thought that force is concentrated in weak parts, reducing the reaction force (proof strength) of the entire part.

[0011] (b) Based on the results of this investigation, we proceeded with development with the idea of ​​smoothing the load transmission in the axial direction (first direction) of the first member, that is, stabilizing the load path so that the first member can withstand the impact load in the first direction.

[0012] Through further analysis using simulations and actual impact tests, we found that the ridge of the first member plays an important role as a transmission path for the impact load, contributing to increasing the strength of the entire part. Therefore, we discovered that by changing the shape of the connection between the first and second members so that the second member is connected to the vertical wall of the first member and the ridge of the first member remains, we can stabilize the load path of the impact force of the first member. Hereinafter, the existence of a ridge that runs continuously without interruption will be referred to as a "continuous ridge."

[0013] (c) Next, in a part where a second member is connected to a vertical wall portion of a first member, we conducted extensive research into the structure of the connection between the two members to ensure the strength of the part. As a result, we discovered that a boss-shaped protrusion that matches the cross-sectional shape of the second member can be provided on the vertical wall portion of the first member to join the two members. At the same time, we discovered that a flange portion (end flange portion) that fits along the vertical wall portion of the first member can be formed on the end portion of the second member that corresponds to the connection portion, and that this flange portion can also be used to join the two members.

[0014] (d) Furthermore, when this part is manufactured by press-forming an integrated blank in which blanks are partially overlapped, it has been found that it is effective to join the two members at the top plate portion of the second member, where there is little material flow during press-forming. Specifically, it has been found that by joining the two members at at least one of the following points: a portion of the boss-shaped protrusion of the first member that corresponds to the top plate portion of the second member (a portion that mates with the top plate portion of the second member after press-forming) and the top plate portion of the second member, or a portion of the standing wall portion of the first member and a portion of the protruding portion (end flange) at the end of the second member that corresponds to the top plate portion of the second member, cracks will not occur during press-forming.

[0015] The present disclosure has been made based on the above findings, and the gist of the disclosure is as follows.

[0016] [1] A blank for press molding of a part, in which a first member extending in a first direction and a second member extending in a second direction intersecting the first direction each have a top plate portion and at least one standing wall portion connected to the top plate portion, and the second member has a portion connected to the first member so as to abut against the first member, wherein the connected portion is formed by partially overlapping a first partial blank corresponding to the first member and a second partial blank corresponding to the second member, the first partial blank has an opening corresponding to the portion where the second member is connected, which is a portion corresponding to the standing wall portion of the first member, and has a boss protrusion that becomes a boss-shaped protrusion at an end along the opening, and the second partial blank has a flange protrusion at an end corresponding to the portion connected to the first member, and at the overlapping portion which is the partially overlapped portion, (A) the boss protrusion of the first partial blank and the portion of the second partial blank that corresponds to the top plate portion of the second member, and (B) the portion of the first partial blank that corresponds to the standing wall portion of the first member and the portion of the flange protrusion of the second partial blank that corresponds to the top plate portion of the second member, A press-molding blank characterized by having either one or both of the above components joined to each other. The part is typically the press-molding blank described in [1] above, in which the second member is connected to the first member so as to abut against the vertical wall portion. [2] The press-molding blank described in [1] above, in which the boss protrusion has a notch near the boundary between a portion corresponding to the top plate portion of the second member and a portion corresponding to the vertical wall portion of the second member, and the depth of the notch is shorter than the width of the boss protrusion. [3] The press-molding blank described in [1] or [2] above, in which the flange protrusion has a recess near the boundary between a portion corresponding to the top plate portion of the second member and a portion corresponding to the vertical wall portion of the second member, and the depth of the recess is shorter than the width of the flange protrusion. [4] The press-molding blank described in any one of [1] to [3] above, in which the flange protrusion has a tongue portion protruding from at least one of: (C) a portion corresponding to the top plate portion of the second member; or (D) a portion corresponding to the vertical wall portion of the second member. [5] The press-molding blank according to any one of [1] to [4], wherein the part is an automotive part.[6] A component 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 standing wall portion connected to the top plate portion, and a portion where the second member is connected to the first member so as to abut against it, wherein the connected portion of the component is made of a blank (i.e., the integrated blank described in any one of [1] to [5]) formed by partially overlapping a first partial blank corresponding to the first member and a second partial blank corresponding to the second member, wherein the first member has a boss-shaped protrusion portion at a portion corresponding to the standing wall portion of the first member where the second member is connected, and the second member has an end flange portion at an end corresponding to the portion connected to the first member, and at the overlap portion which is the partially overlapped portion, either one or both of: (A) the boss-shaped protrusion portion of the first member and the second member, and (B) the end flange portion of the second member and the standing wall portion of the first member are joined, A part (press-molded part) characterized in that a portion of the first member surrounded by the boss-shaped protrusion is hollow. The part is typically the part (press-molded part) described in [6] above, in which the second member is connected to the standing wall portion of the first member so as to abut against it. [7] The part (press-molded part) described in [6] above, in which the boss-shaped protrusion has a notch near the boundary between a portion corresponding to a top plate portion of the second member and a portion corresponding to a standing wall portion of the second member, and the depth of the notch is shorter than the width of the boss-shaped protrusion. [8] The part (press-molded part) described in [6] or [7] above, in which the end flange portion has a recess near the boundary between a portion corresponding to a top plate portion of the second member and a portion corresponding to a standing wall portion of the second member, and the depth of the recess is shorter than the width of the end flange. [9] The part (press-molded part) according to any one of [6] to [8], wherein the end flange portion has a protruding tongue portion on at least one of (C) a portion corresponding to a top plate portion of the second member, or (D) a portion corresponding to a standing wall portion of the second member, and the tongue portion and the first member are joined together.

[10] The part (press-molded part) according to any one of [6] to [9], wherein the part is an automotive part.

[11] A method for manufacturing a part (i.e., the part (press-molded part) described in any one of [6] to

[10] ) in which a first member extending in a first direction and a second member extending in a second direction intersecting the first direction each have a top plate portion and at least one standing wall portion connected to the top plate portion, and the second member has a portion connected to the first member so as to abut against it, comprising: preparing a first partial blank corresponding to the first member and a second partial blank corresponding to the second member corresponding to the connected portion of the part; forming an opening in the first partial blank that corresponds to the portion corresponding to the standing wall portion of the first member and a boss protrusion that becomes a boss-shaped protrusion at an end along the opening; forming a flange protrusion that becomes an end flange portion at an end corresponding to the portion connected to the first member in the second partial blank; partially overlapping the first partial blank and the second partial blank; and at the overlapping portion which is the partially overlapping portion, (A) the boss protrusion of the first partial blank and the portion of the second partial blank that corresponds to the top plate portion of the second member, and (B) A method for manufacturing a part (press-molded part), comprising: joining one or both of a portion of the first partial blank corresponding to the vertical wall portion of the first member and a portion of the flange protrusion of the second partial blank corresponding to the top plate portion of the second member to form an integrated blank (i.e., the blank for press molding described in any one of [1] to [5]); press-molding the integrated blank; and then joining the unjoined portions of the overlapping portions. This is the method for manufacturing a part (press-molded part) described in

[11] , wherein the unjoined portions of the overlapping portions are one or both of the unjoined portions between the end flange portion of the second member and the vertical wall portion of the first member, and the unjoined portions between the boss protrusion of the first member and the second member. Furthermore, this is the method for manufacturing a part (press-molded part) described in

[11] , wherein the part is typically a part in which the second member is connected to the vertical wall portion of the first member so as to abut against the vertical wall portion of the first member.

[12] A method for manufacturing a part (press-molded part) according to

[11] , wherein the boss protrusion has a notch near the boundary between a portion corresponding to the top plate portion of the second member and a portion corresponding to the standing wall portion of the second member, and the depth of the notch is shorter than the width of the boss protrusion.

[13] A method for manufacturing a part (press-molded part) according to

[11] or

[12] , wherein the flange protrusion has a recess near the boundary between the portion corresponding to the top plate portion of the second member and a portion corresponding to the standing wall portion of the second member, and the depth of the recess is shorter than the width of the flange protrusion.

[14] A method for manufacturing a part (press-molded part) according to any one of

[11] to

[13] , wherein the flange protrusion has a protruding tongue portion on at least one of: (C) a portion corresponding to the top plate portion of the second member; or (D) a portion corresponding to the standing wall portion of the second member; and the tongue portion of the second partial blank and the first member are joined after the press forming.

[15] The method for manufacturing a part (press-molded part) according to any one of

[11] to

[14] , wherein the part is an automotive part.

[0017] According to the above-described aspects of the present disclosure, in a component in which two members having at least a vertical wall portion and a top plate portion are connected so as to intersect, the strength of the connection between the two members can be improved.

[0018] Because Figures 1 and 5 span multiple pages, Figure 1 is divided into Figures 1-1 to 1-4, collectively referred to as Figure 1, and Figure 5 is divided into Figures 5-1 to 5-5, collectively referred to as Figure 5. Figure 1(a) is a schematic diagram of a T-shaped part with a C-shaped cross section, which is an example of the present disclosure. Figure 1(b) is a schematic diagram of an example of the part in Figure 1(a) in which a recess is provided in the flange protrusion. Figure 1(c) is a schematic diagram of an example of the part in Figure 1(b) in which a tongue portion is further provided. Figure 1(d) is a schematic diagram of an example of the part in Figure 1(b) in which a tongue portion is further provided. Figure 1(e) is a schematic diagram of a T-shaped part with a hat-shaped cross section, which is an example of the part in Figure 1(a) in which flange portions are provided in the first and second members. Figure 1(f) is a schematic diagram of an example of the part in Figure 1(e) in which a recess is provided in the flange protrusion. FIG. 1( g) is a schematic diagram of an example in which the part of FIG. 1( f) is further provided with a tongue portion. FIG. 1( h) is a schematic diagram of an example in which the part of FIG. 1( f) is further provided with a tongue portion. FIG. 2 is a schematic diagram of the first member (side member) of FIG. 1. FIG. 3 is a schematic diagram of an example of a conventional T-shaped part with a C-shaped cross section. FIG. 4 is a schematic diagram of an example of a conventional T-shaped part with a hat-shaped cross section. FIG. 5( a) is a schematic diagram of an integrated blank according to an example of the present disclosure corresponding to the T-shaped part with a C-shaped cross section of FIG. 1( a). FIG. 5( b) is a schematic diagram of an integrated blank according to an example of the present disclosure corresponding to the T-shaped part with a C-shaped cross section of FIG. 1( b), illustrating an example in which a recess is provided. FIG. 5( c) is a schematic diagram of an integrated blank according to an example of the present disclosure corresponding to the T-shaped part with a C-shaped cross section of FIG. 1( c), illustrating an example in which a tongue portion is provided. FIG. 5(d) is a schematic diagram of an integrated blank according to an example of the present disclosure, corresponding to the T-shaped part with a C-shaped cross section shown in FIG. 1(d), illustrating an example in which a tongue portion is provided. FIG. 5(e) is a schematic diagram illustrating a flange protrusion. FIG. 6(a) is a schematic diagram illustrating a notch in a boss protrusion in a first partial blank. FIG. 6(b) is a schematic diagram of a first member having a boss protrusion with a notch obtained after press-forming the first partial blank of FIG. 6(a). FIG. 1(a) is a schematic diagram illustrating the appearance of an example in which the intersection angle of the T-shaped part with a C-shaped cross section shown in FIG. 1(a) is an acute angle. FIG. 8 is a schematic diagram illustrating an example of a T-shaped part with a tubular cross section formed by combining the T-shaped parts with a C-shaped cross section shown in FIG. 1(a).Figure 9 is a schematic diagram showing an example of a T-shaped part with a tubular cross section, which is made by combining the T-shaped parts with hat-shaped cross sections shown in Figure 1(e). Figure 10(a) is a schematic diagram of the automotive part that served as the basis for the T-shaped part used in the examples, and Figure 10(b) is a conceptual diagram showing the relationship between time after a collision and reaction force, showing the results of a simulation. Hereinafter, Figures 1(a) to 1(f) will be collectively referred to as Figure 1, and Figures 5(a) to 5(d) will be collectively referred to as Figure 5, etc.

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention (hereinafter simply referred to as the present embodiment) will be described with reference to the drawings.

[0020] <Press-Molded Part> Figure 1 shows an example of a T-shaped part according to this embodiment. Figures 1(a) to 1(d) show a top-view T-shaped part (hereinafter, simply referred to as a T-shaped part based on the top-view shape) consisting of two intersecting C-shaped cross-section members, each having a top plate portion and vertical wall portions extending from both sides of the top plate portion. Figures 1(e) to 1(h) show a top-view T-shaped part consisting of two intersecting hat-shaped cross-section members, each having a top plate portion and vertical wall portions extending from both sides of the top plate portion, and a flange portion connected to the vertical wall portion on the opposite side of the top plate portion. The T-shaped part shown in Figure 1 is an integrated part 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. The second member 2 is connected to the first member 1 so as to abut against the first member 1. Typically, the second member 2 is connected to abut the vertical wall portion 12 of the first member 1. The first member 1 and the second member 2 each have a top plate portion 11, 21 and a standing wall portion 12, 22 connected to the top plate portion. The first member 1 also has a ridge line 14 that extends consistently in the first direction 3 at the connection between the top plate portion 11 and the standing wall portion 12. Figure 2 shows the first member extracted from the T-shaped part in Figure 1(a).

[0021] T-shaped part 307 shown in Figure 3 is an example of a part (a T-shaped part with a C-shaped cross section) press-formed from a single blank, such as a conventional TWB. T-shaped part 308 in Figure 4 also has a similar configuration to that shown in Figure 3 and is an example of a conventional T-shaped part with a hat-shaped cross section. In conventional T-shaped parts 307 and 308 as shown in Figures 3 and 4, the ridge line 14 between the top plate portion and the vertical wall portion of the first member is divided and interrupted at the connection portion between the first member and the second member.

[0022] 1(e) to 1(h), by providing flanges 13, 23 continuing from the upright wall portions on the first and second members having a C-shaped cross section shown in FIGS. 1(a) to 1(d), a T-shaped part 8 having a hat-shaped cross section can be formed. In addition, by placing the second member of the T-shaped part shown in FIG. 1 back-to-back with the first member, a cross-shaped part can be formed.

[0023] When these components are manufactured by press-forming an integrated blank, the problem at the connection between the first and second components is the same as that shown in FIG. 1( a). Therefore, both the cross-shaped component and the hat-shaped component share the same challenge of stabilizing the load path caused by an impact force in the axial direction (first direction) of the first component. For this reason, the measures discussed for the C-shaped component (T-shaped component with a C-shaped cross section) shown in FIG. 1( a) can be applied to components with various shapes. For these reasons, this embodiment will be described below using the T-shaped component with a C-shaped cross section (hereinafter referred to as this component) shown in FIG. 1( a).

[0024] As mentioned above, it was found that in this component, the ridge 14 of the first member plays an important role as a transmission path for the impact load, and contributes to increasing the axial strength of the entire component. Therefore, the shape of the connection between the first member 1 and the second member 2 is changed so that the second member 2 is connected to the vertical wall portion 12 of the first member so that the ridge 14 of the first member passes through consistently, thereby stabilizing the load path of the impact force of the first member.

[0025] Furthermore, a boss-shaped protrusion 15 that matches the cross-sectional shape of the second member is provided on the upright wall portion 12 of the first member, and an end flange portion 25 is formed as a flange-shaped protrusion that follows the upright wall portion 12 of the first member at the end portion corresponding to the connection portion of the second member, so that the two members are joined at either or both of (A) the overlapping portion between the boss-shaped protrusion 15 of the first member and the second member 2, and (B) the overlapping portion between the end flange portion 25 of the second member and the first member 1.

[0026] With this configuration, for an impact force applied in the axial direction (first direction) of the first member, the ridge line 14 of the first member runs consistently through the first member 1, stabilizing the load path and ensuring the axial strength of the entire part against the impact force. Furthermore, the second member 2 and the first member 1 are joined to each other at the boss-shaped protrusion 15 of the first member and the end flange 25 of the second member, ensuring the load path and ensuring the crushing strength of the entire part.

[0027] Figure 2 shows a schematic diagram of the first member of this component. The boss-shaped protrusion 15 of the first member 1 is press-formed to fit the inner surface of the second member 2. Therefore, the portion of the press-formed component surrounded by the boss-shaped protrusion 15 becomes a cavity corresponding to the C-shaped cross-sectional shape of the second member 2. This cavity allows the C-shaped cross-sectional cavity of the first member 1 to communicate with the C-shaped cross-sectional cavity of the second member 2.

[0028] That is, the press-molded part according to this embodiment is a part in which a first member 1 extending in a first direction 3 and a second member 2 extending in a second direction 4 intersecting the first direction 3 each have a top plate portion 11, 21 and at least one standing wall portion 12, 22 connected to the top plate portion, and the second member 2 has a portion connected to the first member 1 so as to abut against the first member 1, and the connected portion of the part is constituted by an integrated blank formed by partially overlapping a first partial blank 110 corresponding to the first member 1 and a second partial blank 120 corresponding to the second member 2, and the first member 1 has a boss-like protrusion portion 15 at a portion 12 corresponding to the standing wall portion of the first member where the second member 2 is connected, and the second member 2 has an end flange portion 25 at an end corresponding to the portion connected to the first member 1, and in an overlapping portion 130 which is the partially overlapping portion, (B) A part (press-molded part) characterized in that either one or both of the end flange portion 25 of the second member 2 and the standing wall portion 12 of the first member are joined, and the portion surrounded by the boss-shaped protrusion portion 15 of the first member 1 is hollow. Typically, this is a part (press-molded part) in which the second member 2 is connected to the standing wall portion 12 of the first member so as to abut against it.

[0029] <Integrated Blank> A blank was prepared for press forming the part. The blank was a tailored blank (TWB) constructed by partially overlapping a first partial blank corresponding to the first component (a majority of which will become the first component) and a second partial blank corresponding to the second component (a majority of which will become the second component). (Unless otherwise noted, a TWB constructed by overlapping two or more partial blanks may be referred to as an integrated blank in this specification.) When overlapping, the second partial blank was placed over the first partial blank so that the mating component, i.e., the second component, was positioned at the connection portion of the first component. For example, Figures 5(a) to 5(e) show schematic diagrams of integrated blanks for a C-shaped cross section corresponding to Figures 1(a) to 1(e). These integrated blanks are composed of a first partial blank 110 and a second partial blank 120, and the first partial blank 110 and the second partial blank 120 are arranged so that a portion 121 (top plate portion of the second partial blank) corresponding to the top plate portion of the second member of the second partial blank and a portion 112 (standing wall portion of the first partial blank) corresponding to the standing wall portion of the first member of the first partial blank at least overlap. Figure 5(a) shows an overlapping portion 130 (shaded portion) of the first partial blank 110 and the second partial blank 120. Note that in Figures 5(b) to 5(e), the overlapping portion 130 is omitted to avoid complication.

[0030] The first partial blank 110 has a portion 112 corresponding to the upright wall of the first member, an opening 116 (a hollow portion) corresponding to the portion where the second member is connected, and a boss protrusion 115 that becomes the boss-like protrusion 15 at the end of the first partial blank along the opening 116. By providing the opening 116 in the first member, a structure can be created in which the interiors of the first member and the second member are penetrated when the second member is connected. Furthermore, by providing the opening 116, the complex material flow behavior of the first member can be suppressed at this connection portion.

[0031] The second partial blank 120 has a flange protrusion 125 at the end corresponding to the portion connected to the first member, which becomes the end flange portion 25, which is a flange-shaped connecting portion. For ease of explanation, the boundary lines between the flange protrusion 125 and the top plate portion 121 and the standing wall portion 122 of the second partial blank are shown by dotted lines in Figure 5(a).

[0032] To integrate the two partial blanks, the overlapping portion (the overlapping portion 130) of the two blanks is joined. However, if the two partial blanks 110, 120 are joined over the entire overlapping portion 130, the joining restricts material flow at the vertical wall portions (and flange portions, if present, such as in the case of a hat-shaped cross section) that correspond to the corners of the parts' connections during press forming, causing excessive strain in the material and making it more susceptible to cracking. On the other hand, the portion 121 corresponding to the top plate portion of the second component experiences less material flow and is less susceptible to cracking. Therefore, it is preferable to join the overlapping portion 130 at one or both of the top plate portion 121 of the second partial blank and the portion of the flange protrusion 125 of the second partial blank that corresponds to the top plate portion 121 of the second component.

[0033] That is, at least a portion of either or both of (A) the portion of the boss protrusion 115 of the first partial blank corresponding to the top plate portion of the second member and the top plate portion 121 of the second partial blank, and (B) the vertical wall portion 112 of the first partial blank and the portion of the flange protrusion 125 of the second partial blank corresponding to the top plate portion of the second member, are joined to form an integrated blank.

[0034] By joining only at least a portion of the overlapping portion 130 that corresponds to the top plate portion of the second member in this manner, both partial blanks can exhibit deformation behavior during press forming as if they were separate blanks. In other words, both partial blanks can deform freely, and cracking that occurs during press forming can be avoided.

[0035] The method for joining the two blanks is not particularly limited. For example, joining by welding such as spot welding, lap welding, and lap fillet welding is preferred. In particular, spot welding is preferred from the viewpoint of workability. The type of welding is not particularly limited. Resistance welding, laser welding, and the like may be selected as appropriate. For example, spot welding (resistance welding, laser spot welding) is preferred from the viewpoints of applicability to complex shapes, cost, workability, and efficiency.

[0036] That is, the press-molding blank according to this embodiment is a blank for press-molding of a part, in which a first member 1 extending in a first direction 3 and a second member 2 extending in a second direction 4 intersecting the first direction 3 each have a top plate portion 11, 21 and at least one standing wall portion 12, 22 connected to the top plate portion 11, 21, and the second member 2 has a portion where it is connected to the first member 1 so as to abut against the top plate portion 11, 21, and the connected portion is formed by partially overlapping a first partial blank 110 corresponding to the first member 1 and a second partial blank 120 corresponding to the second member 2, the first partial blank 110 has an opening 116 in a portion 112 corresponding to the standing wall portion of the first member, which corresponds to the portion where the second member 2 is connected, and has a boss protrusion 115 which becomes a boss-shaped protrusion 15 at an end along the opening 116, the second partial blank 120 has a flange protrusion 125 at an end corresponding to the portion connected to the first member 1, and in an overlapping portion 130 which is the partially overlapping portion, This press-forming blank is characterized in that either one or both of the following are joined: (A) the boss protrusion 115 of the first partial blank 110 and a portion 121 of the second partial blank corresponding to the top plate portion of the second member, and (B) a portion 112 of the first partial blank corresponding to the standing wall portion of the first member and a portion 121 of the flange protrusion 125 of the second partial blank 120 corresponding to the top plate portion of the second member. Typically, this is a press-forming blank for a part in which a second member is connected so as to abut against the standing wall portion of the first member.

[0037] <Boss protrusion> As described above, the first partial blank has an opening 116 (a hollow portion) that corresponds to the vertical wall portion of the first member and corresponds to the portion where the second member is connected, and has a boss protrusion 115 that becomes the boss-like protrusion 15 at the end of the first partial blank along the opening 116. By providing this boss protrusion, the boss protrusion of the first partial blank is formed to fit along the inner surface of the second member during press forming, becoming the boss protrusion 15. By joining the boss protrusion and the inner surface of the second member, bending strength against bending of the second member can be ensured. Preferably, the boss-like protrusion 15 and the unjoined portion of the second member are joined after press forming.

[0038] The width (protruding length) of the boss protrusion is not particularly limited. It is desirable to ensure a length that allows joining between the first and second partial blanks at the overlapping portion. For example, when joining by spot welding, it is preferable to ensure an area at least twice the diameter of the spot weld. From this perspective, the length of the protrusion should be, for example, 20 mm or more, preferably 30 mm or more.

[0039] On the other hand, if the width (protrusion length) of the boss protrusion is too long, it will exhibit complex material flow behavior during press forming, so it is preferable that it is not too long and that it is long enough to ensure the necessary bonding area. Also, ensuring the boss protrusion may result in the first partial blank having an irregular shape, which may reduce material yield when cutting it out from the raw material (steel plate). Therefore, it is preferable that the length of the first partial blank be commensurate with the original plate (steel plate) of the first partial blank.

[0040] <Notch in Boss Protrusion> The boss protrusion may have a notch formed by removing a portion thereof. As described above, even with the opening 116, the boss protrusion exhibits complex material flow behavior during press forming. In particular, near the boundary between the top plate portion and the vertical wall portion of the second partial blank, the second partial blank deforms in accordance with the deformation of the first partial blank, resulting in extremely complex material flow behavior. Therefore, it is preferable to provide a notch in advance in the portion exhibiting this complex material flow behavior, i.e., near the boundary between the top plate portion and the vertical wall portion of the second component, to mitigate the complex material flow. Figure 6(a) is a schematic diagram of an example of a first partial blank corresponding to this part. As shown in Figure 6(a), a notch 117 may be provided in the boss protrusion 115 near the boundary between the top plate portion and the vertical wall portion of the second component. The depth of this notch 117 should be shorter than the width of the boss protrusion 115 (boss-like protrusion) so that the boss protrusion 115 is not divided. In other words, after press molding, the boss protrusion 15 should be continuous in the alignment direction from one standing wall portion to the top plate portion and then to the other standing wall portion of the corresponding second member. Figure 6(b) is a schematic diagram showing an example of a first member having a notch 16 in the boss protrusion 15 after press molding.

[0041] The shape of the notch 117 is not particularly limited. For example, a simulation such as FEM (Finite Element Method) can be used to understand the material flow behavior, identify areas where the strength exceeds a reference value (e.g., the shear fracture strength of the steel plate used as the material), and create the notch 117. The depth of the notch 117 is set shorter than the width (protrusion length) of the boss protrusion 115. If the notch were formed across the entire width of the boss protrusion 115, the boss-shaped protrusion 115 would be divided after press forming, which could limit the transmission of force when the second member is joined, potentially causing localized damage to the joint. The method for forming the notch 117 is not particularly limited, but it is preferable that the bottom (tip) of the notch have a relatively large radius of curvature to prevent it from becoming a starting point for cracks or the like.

[0042] <Flange Protrusion> As described above, the second partial blank has a flange protrusion 125 at the end corresponding to the portion connected to the first member, which will become the flange-shaped end flange portion 25 after press forming. That is, the flange protrusion is provided continuously with the portion of the second blank corresponding to the top plate portion of the second member and the portion corresponding to the standing wall portion. More specifically, the portion of the flange protrusion corresponding to the top plate portion of the second member is a portion of the second partial blank that is arranged continuously with the portion corresponding to the top plate portion of the second member and corresponds to an extension of the top plate portion of the second member. Similarly, the portion of the flange protrusion corresponding to the standing wall portion of the second member is a portion of the second partial blank that is arranged continuously with the portion corresponding to the standing wall portion of the second member and corresponds to an extension of the standing wall portion of the second member. The flange protrusion may be provided on at least a portion of the portion of the second partial blank that corresponds to the top plate portion of the second member and the portion corresponding to the standing wall portion. The flange protrusion 125 is provided on the portion of the second partial blank that corresponds to the top plate portion of the second member and the standing wall portion. By joining this flange protrusion to the upright wall portion of the first partial blank, bending strength against bending of the second member can be ensured.

[0043] The flange protrusion of the second partial blank is formed to fit along the vertical wall portion of the first member during press forming, and after press forming, the flange protrusion 125 can be joined to the unjoined portion of the first member, thereby forming an integrated part.

[0044] 5( e), the flange protrusion 125 is provided across the upright wall portion 122 and the top plate portion 121 of the second partial blank, and when the second partial blank is superimposed on the first partial blank, it becomes a portion (a portion of the first partial blank on the upright wall portion side) beyond the line (the upper end of the boss protrusion 115) corresponding to the boundary between the boss protrusion 115 of the first partial blank and the portion 112 corresponding to the upright wall portion of the first member. By arranging it in this manner, the flange protrusion 125 is deformed into a flange shape so as to fit along the upright wall portion of the first member during press forming, and becomes the end flange portion 25 of the press-formed part.

[0045] It is desirable for the flange protrusion to fit within the vertical wall portion of the first member as closely as possible. When the flange protrusion deforms from the vertical wall portion of the first member to the top plate portion, the deformation of the flange protrusion becomes complex. In particular, the portion of the flange protrusion corresponding to the vertical wall portion 122 of the second partial blank deforms to fit along the vertical wall portion of the first member and to conform to the vertical wall of the second member, resulting in extremely complex material flow behavior. Therefore, as shown in FIG. 5( e), it is preferable for the portion of the flange protrusion 125 corresponding to the vertical wall portion 122 of the second partial blank to fit within the portion of the first partial blank corresponding to the vertical wall portion of the first member (the vertical wall portion of the first partial blank) 112. In this way, the flange protrusion 126 deforms to fit along the vertical wall portion of the first member during press forming, and in the press-formed part after press forming, it becomes an end flange portion that fits within the vertical wall portion of the first member (see FIG. 1( a)).

[0046] The length L of the flange protrusion 125 (length in the second direction (see Figure 5 (e))) is not particularly limited. From the viewpoint of joining the first partial blank and the second partial blank at the overlapping portion, it is desirable to ensure a length that allows joining. For example, when joining by spot welding, it is preferable to ensure an area that is at least twice the spot weld diameter, and from this viewpoint, the length L of the flange protrusion may be, for example, 20 mm or more, preferably 30 mm or more.

[0047] On the other hand, if the flange protrusion is too long, the second partial blank will have an irregular shape to ensure the protrusion, which will reduce the material yield when cutting it out from the raw material (steel plate). Therefore, it is preferable to make the length of the second partial blank commensurate with the original plate (steel plate).

[0048] As mentioned above, it is desirable to have the flange protrusion 125 fit within the vertical wall portion of the first member as much as possible, so it is desirable to set the length L of the flange protrusion 125 to a length that fits within the portion 112 of the first partial blank that corresponds to the vertical wall portion of the first member (the vertical wall portion of the first partial blank) (see Figure 5 (e)).

[0049] The flange protrusion can have any shape as long as it can be deformed into a flange shape by press molding and can connect the second member to the first member so that they butt against each other. The flange protrusion can be, for example, a substantially rectangular or semicircular shape, or a trapezoidal shape with a length shorter than a width and a width that narrows slightly toward the tip, as shown in Figure 5(e). The tip of the flange protrusion can also be linear or arc-shaped.

[0050] <Recess in Flange Protrusion> The flange protrusion may have a recess formed by removing a portion thereof. As described above, the flange protrusion undergoes complex deformation during press forming, resulting in complex material flow behavior. In particular, near the boundary between the top plate portion and the vertical wall portion of the second partial blank, the second partial blank deforms in accordance with the deformation of the first partial blank, resulting in extremely complex material flow behavior. Therefore, it is preferable to provide a recess in advance in the portion exhibiting this complex material flow behavior, i.e., near the boundary between the portion corresponding to the top plate portion and the vertical wall portion of the second component, to mitigate the complex material flow. Figure 5(b) is a schematic diagram of an example of an integrated blank in which a recess 126 is provided in the flange protrusion 125 of the second partial blank 120 of Figure 5(a). As shown in Figure 5(b), a recess 126 may be provided in the flange protrusion 125 of the second partial blank near the boundary between the portion 121 corresponding to the top plate portion of the second component and the portion 122 corresponding to the vertical wall portion. The depth of this recess 126 should be shorter than the width of the flange protrusion 125 (end flange portion) so that the flange protrusion 125 (end flange portion) is not divided. In other words, after press molding, the end flange portion 25 should be continuous in the alignment direction from one vertical wall portion of the second member to the top plate portion and the other vertical wall portion. Figure 1(b) schematically shows an example of this part having a recess 26 in the end flange portion 25 after press molding.

[0051] There is no particular limitation on the shape of the recess 126. For example, it is conceivable to grasp the material flow behavior by a simulation such as FEM (Finite Element Method), identify a portion where the material has a shear fracture strength equal to or greater than a reference value (for example, the shear fracture strength of the steel plate that is the material), and make that portion the recess 126.

[0052] The depth of the recess 126 (the length in the width direction of the flange protrusion) is made shorter than the width (protrusion length) of the flange protrusion 125. If the recess 126 were formed across the entire width of the flange protrusion 125, the end flange portion 25 would be divided after press molding, which would limit the transmission of force when joined to the first member and could induce localized damage to the joint. There are no particular restrictions on the method for processing the recess 126, but it is preferable that the bottom (tip) of the recess 126 have a relatively large radius of curvature so as not to become a starting point for cracks, etc.

[0053] <Tongue Portion> The flange protruding portion 125 may be provided with one or more tongue-shaped protrusions (tongue portions 131) that further protrude from the flange protruding portion 125. That is, the flange protruding portion 125 may be provided with one or more protruding tongue portions 131. Specifically, as shown in FIGS. 5( c) and 5(d) , the flange protruding portion 125 may be provided with a tongue portion 131 that further protrudes from a portion of the flange protruding portion 125 in the second direction 4 (upward in the plane of the drawing). More specifically, in a case where the flange protruding portion 125 is contained within a portion 112 corresponding to the standing wall portion of the first member of the first partial blank (the standing wall portion of the first partial blank) (see FIG. 5(e) ), a tongue portion 131 that further protrudes from a portion of the flange protruding portion 125 in the second direction 4 may be provided. If a tongue portion 131 is provided, it is preferable to arrange it on the portion 121 of the flange protrusion 125 corresponding to the top plate portion of the second member and the portion 122 corresponding to the vertical wall portion of the second member. Such a tongue portion is formed to conform to the top plate portion or vertical wall portion of the first member after press forming. Therefore, by joining the tongue portion of the second partial blank to the top plate portion or vertical wall portion of the first partial member after press forming, the strength of the integrated part can be increased. The width of the tongue portion 131 is preferably narrower than the flange protrusion 125 so that the tongue portion only undergoes simple bending deformation during press forming. This is because the lack of complex material flow behavior can prevent cracks from occurring during press forming.

[0054] The location of the tongue portion is not particularly limited. The location of the tongue portion is not particularly limited, as long as it is the flange protrusion portion of the second partial blank (the end flange portion of the second member). As shown in Figures 5(c) and 5(d), when the flange protrusion portion 125 is located within the portion 112 of the first partial blank corresponding to the vertical wall portion of the first member (the vertical wall portion of the first partial blank), if a protruding tongue portion 131 protruding in the second direction 4 from the flange protrusion portion 125 is provided, it is preferable to arrange the tongue portion 131 on the portion 121 of the flange protrusion portion 125 corresponding to the top plate portion of the second partial blank and the portion 122 corresponding to the vertical wall portion of the second member. If the tongue portion 131 is provided across the vertical wall portion 122 and the top plate portion 121 of the second partial blank, complex deformation occurs during press forming. This is because complex material flow behavior occurs particularly near the boundary between the top plate portion 121 and the vertical wall portion 122 of the second partial blank. For example, the flange protrusion 125 of the second partial blank may have a tongue portion protruding from at least one of (C) a portion 121 corresponding to the top plate portion of the second member and (D) a portion 122 corresponding to the standing wall portion of the second member. Figure 5(d) shows an example in which a tongue portion 131 is provided on each of the portion 121 corresponding to the top plate portion and the portions 122 corresponding to the two standing wall portions of the flange protrusion of the second partial blank. Because these tongue portions are separated from each other, they are simply bent independently during press forming, preventing defects such as cracking.

[0055] The number of tongue portions is not particularly limited. A plurality of tongue portions may be provided for each of (C) and (D) above. When a plurality of tongue portions are provided, it is desirable to arrange them so that they do not interfere with each other after press working. This is because mutual interference can cause defects such as wrinkles during press forming.

[0056] The shape and size of the tongue portion are not particularly limited. The tongue portion may be substantially rectangular or substantially semicircular. The tip of the tongue portion may be linear or arc-shaped.

[0057] The length of the tongue portion (the maximum length in the second direction of the second partial blank) is not particularly limited. The length of the tongue portion provided in the portion of the flange protrusion corresponding to the top plate portion of the second partial blank is desirably set to a length that extends to the top plate portion 111 of the first partial blank so that at least a portion of the tongue portion overlaps the portion 111 of the first partial blank corresponding to the top plate portion of the first member of the first partial blank (top plate portion of the first partial blank). By providing a tongue portion of a length that overlaps the top plate portion of the first partial blank, rigidity can be improved by joining with the first member after press forming.

[0058] The width of the tongue portion (the maximum length of the second partial blank in the direction perpendicular to the second direction) is not particularly limited. As shown in FIGS. 5( c) and 5(d), the tongue portion 131 is a tongue-shaped protrusion protruding in the second direction 4 from a portion of the flange protrusion 125, and therefore may be narrower than the flange protrusion 125. The width of the tongue portion may be the same as the respective widths (maximum length perpendicular to the second direction) of the portion 121 corresponding to the top plate portion of the second partial blank and the portion 122 corresponding to the standing wall portion of the second component. Furthermore, the width of the tongue portion may be shorter than the respective widths (maximum length perpendicular to the second direction) of the portion 121 corresponding to the top plate portion of the second partial blank and the portion 122 corresponding to the standing wall portion of the second component. As described above, the tongue portion of the flange protrusion of the second partial blank is formed to fit along the top plate portion or standing wall portion of the first component after press forming. Joining the tongue portion to the top plate portion or standing wall portion of the first component after press forming increases the strength of the integrated component. Therefore, it is desirable for the tongue portion to have an area large enough for joining. For example, when joining by spot welding, it is desirable for the length and width to be at least twice the spot weld diameter, and the length and width of the tongue portion may be, for example, 10 mm or more, 20 mm or more, and preferably 30 mm or more. For example, when joining the tongue portion by lap fillet welding, the length and width of the tongue portion itself can be reduced, but it is advisable to determine them appropriately based on whether the part shape can ensure a fillet weld allowance and whether the weld length sufficient to obtain the strength of the part can be ensured. It is preferable to determine them appropriately based on the part shape and the shape of the material from which the second partial blank is made. This is because making the shape of the second partial blank irregular in order to ensure the tongue portion not only reduces material yield but also may lead to increased blank processing costs.

[0059] For example, as shown in FIG. 5( c), when the flange protrusion 125 fits into the vertical wall portion 112 of the first partial blank, a tongue portion 131 protruding in the second direction 4 may be provided on the portion 121 of the flange protrusion 125 of the second partial blank that corresponds to the top plate portion of the second component, and the tongue portion 131 may have a length that extends to the top plate portion 111 of the first partial blank so that at least a portion of the tongue portion 131 overlaps the portion 111 of the first partial blank that corresponds to the top plate portion of the first component (the top plate portion of the first partial blank). In this case, the tongue portion is formed during press molding so as to extend from the vertical wall portion of the first component to the top plate portion. Therefore, by joining the tongue portion of the second partial blank and the top plate portion of the first component after press molding, the strength of the integrated part can be increased. 5(c), the tongue portion 131 may be rectangular and have approximately the same width as the top plate portion 121 of the second partial blank, i.e., the same width as the distance between the two recesses 126. Fig. 5(c) shows an example in which the tongue portion 131 having approximately the same width as the top plate portion 121 of the second partial blank is provided only on the portion of the flange protruding portion 125 of the second partial blank that corresponds to the top plate portion 121 of the second member, but in addition to this, the tongue portion 131 having approximately the same width as the upright wall portion of the second partial blank may be provided on the portion 122 that corresponds to the upright wall portion of the second partial blank. 5(c) shows an example in which a tongue portion 131 is provided on a flange protrusion 125 having a recess 126, but a tongue portion 131 of approximately the same width as the top plate portion 121 of the second partial blank may be provided on a portion 121 of the flange protrusion 125 (see FIG. 5(a)) that does not have a recess 126, which corresponds to the top plate portion of the second partial blank. FIG. 1(c) schematically shows an example of a part having a recess 26 and a tongue portion 27 on the end flange portion 25 after press forming corresponding to FIG. 5(c). As shown in FIG. 1(c), even when a tongue portion 27 is provided, the ridge line 14 of the first member 1 extending in the first direction 3 passes through the connection portion of the first member 1 consistently.

[0060] 5(d), for example, when the flange protrusion 125 fits into the standing wall portion 112 of the first partial blank, a tongue portion 131 protruding in the second direction 4 (upward in the drawing) may be provided on each of the portion 121 corresponding to the top plate portion of the second member of the second partial blank and the portion 122 corresponding to the standing wall portion of the second member of the second partial blank. In this case, the length of the tongue portion 131 may be set so that, when the second partial blank is placed on top of the first partial blank, its tip reaches the portion 111 corresponding to the top plate portion of the first member of the first partial blank (the top plate portion of the first partial blank). In this case, during press molding, the tongue portion 131 provided on the portion 121 corresponding to the top plate portion of the second member of the second partial blank is molded so as to follow the top plate portion from the vertical wall portion of the first member, and the tongue portion 131 provided on the portion 122 corresponding to the vertical wall portion of the second member of the second partial blank is molded so as to follow the vertical wall portion of the first member.

[0061] Preferably, the tongue portion 131 provided on the portion 122 of the second partial blank corresponding to the standing wall portion of the second member is of a length that does not overlap the top plate portion 11 of the first member after press forming. Even more preferably, when the first partial blank and the second partial blank are overlapped, the tongue portion 131 provided on the portion 122 of the second partial blank corresponding to the standing wall portion of the second member is not overlapped with the top plate portion 111 of the first partial blank.

[0062] 5(d), the tongue portion 131 may be rectangular and have a width narrower than the widths of the top plate portion 121 of the second partial blank and the standing wall portion 122 of the second partial blank, and may be 90% or less, 80% or less, 70% or less, 60% or less, or 50% or less of the respective widths. In FIG. 5(d), an example is shown in which the tongue portion 131 is provided on each of the portion 121 corresponding to the top plate portion and the portion 122 corresponding to the standing wall portion of the flange protrusion 125 of the second partial blank, but the tongue portion 131 having a width narrower than the top plate portion 121 of the second partial blank may be provided only on the portion 121 corresponding to the top plate portion of the flange protrusion 125 of the second partial blank. Although FIG. 5(d) shows an example in which a tongue portion 131 is provided on a flange protrusion 125 having a recess 126, a tongue portion 131 narrower than the top plate portion or the upright wall portion of the second partial blank may be provided on a portion 121 corresponding to the top plate portion or the upright wall portion of the second partial blank of the flange protrusion 125 (see FIG. 5(a)) that does not have a recess 126. An example of this part having a recess 26 and a tongue portion 27 on the end flange portion 25 after press forming corresponding to FIG. 5(d) is schematically shown in FIG. 1(d). Even when a tongue portion 27 is provided as shown in FIG. 1(d), the ridge line 14 of the first member 1 extending in the first direction 3 passes through the connection portion of the first member 1.

[0063] <Intersection Angle Between First Member and Second Member> The intersection angle between the first member and the second member, i.e., the intersection angle between the first direction and the second direction, is not particularly limited. FIG. 7 shows a schematic diagram of an L-shaped part in which the intersection angle between the first member 1 and the second member 2, i.e., the intersection angle between the first direction 3 and the second direction 4, is θ. While FIG. 7 illustrates an acute angle (90° or less) for the intersection angle θ, it may 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 may be set appropriately depending on the processing accuracy of the press molding. Similarly, the upper limit of the intersection angle θ is not particularly limited as long as it is less than 180°. For example, when L-shaped parts corresponding to opposite sides are integrated as shown in FIGS. 3 and 4, the intersection angle of the opposite members becomes an acute angle and is set appropriately depending on the processing accuracy of the press molding.

[0064] <Other Aspects of Press-Molded Parts> A part (press-molded part) obtained by integrally press-molding an integrated blank composed of the first partial blank and the second partial blank described above is an integrated part. As described above, the T-shaped part with a C-shaped cross section shown in FIG. 1 is the basic shape, and a cross-shaped part can be obtained by combining these parts. Similarly, a part with a shape combining a T or a cross, such as a lattice-like part, can also be obtained as an integrated part by combining the T-shaped parts shown in FIG. 1.

[0065] Furthermore, by stacking these integrated parts one on top of the other, parts with, for example, tubular cross sections can be obtained. For example, by combining and joining two T-shaped parts 7 with C-shaped cross sections shown in Fig. 1(a) one on top of the other, a T-shaped part 207 with a hexagonal cross section without a flange, as shown in Fig. 8, can be obtained. Similarly, by combining and joining two T-shaped parts 8 with hat-shaped cross sections shown in Fig. 1(e) one on top of the other, a T-shaped part 208 with a hexagonal cross section and a flange, as shown in Fig. 9, can be obtained.

[0066] In the conventional method, the first and second members were press-formed separately and then joined together to obtain the product, so it was confirmed that this embodiment realizes extremely high efficiency in terms of workability. In particular, in the case of a part that combines multiple L-shaped parts, what would have been done by press-forming individual members and welding them together can now be obtained as an integrated part by press-forming, so the effect of this embodiment is extremely significant.

[0067] Furthermore, compared to conventional parts obtained by press-forming a single blank, the part (press-formed part) according to this embodiment has a consistent ridgeline of the first member, which ensures smooth load transfer (a stable load path) and ensures the strength of the entire part. This ensures a sufficient reaction force (proof strength) against collision loads, and applying this structure to the part structures of transportation equipment such as automobiles can improve collision performance. For example, in parts connected in a T-shape, such as an automobile's side member and cross member, the reduction in reaction force (proof strength) against an axial impact force of the member corresponding to the side member at the connection point can be suppressed, ensuring the strength of the part connection point.

[0068] Furthermore, since the strength of the entire part is ensured and the collision performance is improved, it is possible to reduce the required plate thickness of the first member, and the weight of the part can be reduced.

[0069] Furthermore, the radius of curvature of the corners of the second member can be reduced. By providing a boss-like protrusion on the first member and using the boss-like protrusion to support the second member, the connection structure of the two members is simplified, and cracks that occur during integral press molding can be suppressed. This makes it easier to deform the connection portion of the first member, and as a result, the radius of curvature of the corners of the first and second members can be reduced.

[0070] In conventional press forming using a single blank (including tailored blanks (TWBs) made by butt-welding partial blanks), the radius of curvature of the corners of the first and second members was at most about 80 mm, but it was confirmed that when this embodiment is applied, it is possible to manufacture members with a radius of curvature of 15 mm. This is because, in the case of frame members for automobiles, for example, the mounting capacity of parts increases by the amount that the radius of curvature of the corners becomes smaller.

[0071] The use of the part according to this embodiment is not particularly limited. For example, it can be applied to automobile parts. Examples of automobile parts include components of a front module (e.g., a front side member and a cross member), a side sill (rocker) and a floor cross member, a floor tunnel and a floor cross member, and components of a rear under module (e.g., a rear side member and a cross member). When applied to automobile parts, it is expected that the ease of getting in and out can also be improved. Needless to say, the part (press-molded part) according to this embodiment can be widely applied not only to automobiles but also to structures such as transportation machinery and general machinery.

[0072] <Method for manufacturing a component> In the method for manufacturing a component according to this embodiment, other than manufacturing the integrated blank described above, known methods such as press forming, welding (spot welding), etc. can be applied. To reiterate, the method for manufacturing a component according to this embodiment is as follows.

[0073] - preparing a first partial blank corresponding to the first member and a second partial blank corresponding to the second member; - forming an opening in the first partial blank that corresponds to the upright wall portion of the first member and that connects to the second member, and a boss protrusion that will become a boss-shaped protrusion at the end along the opening; - forming a notch in the boss protrusion as necessary; - forming a flange protrusion that will become an end flange portion in the second partial blank at the end that corresponds to the portion that connects to the first member; - forming a recess in the flange protrusion as necessary; - forming a tongue portion in the flange protrusion as necessary; - partially overlapping the first blank and the second blank; - forming an integrated blank at the overlapping portion, which is the partially overlapping portion, by joining either one or both of: (A) the boss protrusion of the first partial blank and the portion of the second partial blank that corresponds to the top plate portion of the second member, and (B) the portion of the first partial blank that corresponds to the upright wall portion of the first member and the portion of the flange protrusion of the second partial blank that corresponds to the top plate portion of the second member; - press-forming the formed integrated blank; - Then, the unjoined parts of the overlapping portions are joined, and - if a tongue portion is further provided on the flange protrusion as necessary, a part (press-molded part) is obtained by joining the tongue portion and the first member after press molding.

[0074] The unjoined portion of the overlapping portion is the unjoined portion of one or both of the end flange portion of the second member and the vertical wall portion of the first member, and the unjoined portion of the boss protrusion portion of the first member and the second member.

[0075] The component is typically a component in which the second member is connected to the upright wall portion of the first member so as to abut against the upright wall portion of the first member.

[0076] The press forming method is not particularly limited. Any known press forming method can be used. 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 used.

[0077] The method for joining the portions of the first and second partial blanks that are not joined at the overlapping portion after press forming (including the joining of the tongue portion of the first and second partial blanks) is not particularly limited. For example, joining by welding such as spot welding, lap welding, and lap fillet welding is preferred. In particular, from the viewpoint of workability, joining by spot welding is preferred. The type of welding is not particularly limited. Resistance welding, laser welding, and the like may be selected and determined as appropriate. For example, spot welding (resistance welding, laser spot welding) is preferred from the viewpoints of applicability to complex shapes, cost, workability, and efficiency.

[0078] Assuming the rear under module of an automobile shown in FIG. 10(a), rear-end collision tests were simulated and analyzed by changing the connection structure between the side members and the cross members. <Test specifications> ・Regulatory test: Complies with US FMVSS 301 ・Barrier type: Deformable aluminum honeycomb barrier ・Collision speed: 80 km / h ・Barrier weight: 1,360 kg ・Lapping rate: 70% ・Steel type: 1 GPa to 2 GPa-class hot-stamped steel plate ・Side member rearward from cross member: 1 GPa-class hot-stamped steel plate, thickness t1.0 mm ・T-shaped abutment part of cross member of side member: 2 GPa-class hot-stamped steel plate, thickness t2.0 mm ・Frontward from T-shaped abutment part of cross member of side member: 2 GPa-class hot-stamped steel plate, thickness t1.4 mm ・Cross member: 1.5 GPa-class hot-stamped steel plate, thickness t1.0 mm ・Overall width (cross direction): 1,400 mm ・Overall length (front-rear (side) direction): 1,600 mm ・Overall module height: 460 mm

[0079] <Test Levels> [Level 1] Comparative Example: A type in which the ridgeline of the side member is divided (a single blank (conventional TWB) with no overlapping portion) is press (hot stamped) formed. (Equivalent to a part obtained by combining the hat-shaped cross-section members in FIG. 4 ). [Level 2] Example A: An integrated blank according to the present embodiment, in which the ridgeline of the side member is consistent (ridgeline is maintained) (a case in which the first member has a boss-like protrusion and the second member has an end flange (without a tongue portion)), is press (hot stamped) formed according to the manufacturing method of the present embodiment. (Equivalent to A in FIG. 10(a)). [Level 3] Example B: An integrated blank according to the present embodiment, in which the ridgeline of the side member is consistent (ridgeline is maintained) (a case in which the first member has a boss-like protrusion and the second member has an end flange (with a tongue portion joined to the top plate portion of the side member)), is press (hot stamped) formed according to the manufacturing method of the present embodiment. (Equivalent to B in FIG. 10(a)).

[0080] <Test Results> The simulation results are shown in Figure 10(b). After a collision, the reaction force increases over time, but it is first generated by the deformation of the bumper body. Because the bumper structure is the same between the levels, there is no difference in the reaction force behavior in this area. However, after the bumper deforms, the side members counteract the impact load, and the difference between the levels becomes clear.

[0081] It can be seen that in Level 1 (comparison example) where the ridge line is divided, the side member cannot withstand the impact load and the reaction force does not increase.

[0082] On the other hand, it can be seen that Level 2 (Example A) and Level 3 (Example B), which pass through the ridgeline, have an increased reaction force against the impact load. There is no significant difference between Level 2 (Example A) and Level 3 (Example B). This is thought to be because the tongue portion installed on the end flange of the cross member does not contribute to the axial impact force of the side member. This is because this tongue portion is able to resist bending deformation of the cross member.

[0083] From the above, it has been confirmed that by applying this embodiment, a part that increases the resistance of the first member (side member) to axial impact forces can be obtained by integral press molding using an integrated tailored blank.

[0084] The present disclosure can be widely used in a wide range of industrial fields, such as the transportation machinery industry (e.g., automobiles), the general machinery industry, and electrical equipment.

[0085] 1 First member 2 Second member 3 First direction 4 Second direction 7 T-shaped part with C-shaped cross section (press-molded part) 8 T-shaped part with hat-shaped cross section (press-molded part) 9 T-shaped part with hexagonal cross section (press-molded part) 10 T-shaped part with hexagonal cross section with flange (press-molded part) 11 Portion corresponding to top plate portion of first member (top plate portion of first member) 12 Portion corresponding to standing wall portion of first member (standing wall portion of first member) 13 Portion corresponding to flange portion of first member (flange portion of first member) 14 Ridge line of first member 15 Boss-shaped protrusion 16 Notch in boss-shaped protrusion 21 Portion corresponding to top plate portion of second member (top plate portion of second member) 22 Portion corresponding to standing wall portion of second member (standing wall portion of second member) 23 Portion corresponding to flange portion of second member (flange portion of second member) 25 End flange portion 26 Recessed portion of end flange portion 27 Tongue portion 110 First partial blank 111 Portion of first partial blank corresponding to the top plate portion of first member (top plate portion of first partial blank) 112 Portion of first partial blank corresponding to the standing wall portion of first member (standing wall portion of first partial blank) 115 Boss protrusion portion 116 Opening 117 Notch of boss protrusion 120 Second partial blank 121 Portion of second partial blank corresponding to the top plate portion of second member (top plate portion of second partial blank) 122 Portion of second partial blank corresponding to the standing wall portion of second member (standing wall portion of second partial blank) 125 Flange protrusion portion 126 Recessed portion of flange protrusion L Length of flange protrusion 130 Overlapping portion 131 Tongue portion 207 T-shaped part with hexagonal cross section (without flange) 208 T-shaped part with hexagonal cross section (with flange) 307 Conventional T-shaped part with C-shaped cross section 308 Conventional T-shaped part with hat-shaped cross section

Claims

1. A blank for press molding of a part, in which a first member extending in a first direction and a second member extending in a second direction intersecting the first direction each have a top plate portion and at least one standing wall portion connected to the top plate portion, and the second member has a portion where it is connected to the first member so as to abut against the first member, wherein the connected portion is formed by partially overlapping a first partial blank corresponding to the first member and a second partial blank corresponding to the second member, the first partial blank has an opening corresponding to the portion where the second member is connected, which is a portion corresponding to the standing wall portion of the first member, and has a boss protrusion that becomes a boss-shaped protrusion at an end along the opening, and the second partial blank has a flange protrusion at an end corresponding to the portion where it is connected to the first member, and at the overlapping portion which is the partially overlapped portion, (A) the boss protrusion of the first partial blank and the portion of the second partial blank that corresponds to the top plate portion of the second member, and (B) the portion of the first partial blank that corresponds to the standing wall portion of the first member and the portion of the flange protrusion of the second partial blank that corresponds to the top plate portion of the second member, A press-forming blank characterized in that either one or both of the above is bonded.

2. A press-molding blank as described in claim 1, wherein the boss protrusion has a notch near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the standing wall portion of the second member, and the depth of the notch is shorter than the width of the boss protrusion.

3. A press-molding blank as described in claim 1 or 2, wherein the flange protrusion has a recess near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the vertical wall portion of the second member, and the depth of the recess is shorter than the width of the flange protrusion.

4. A press-molding blank according to any one of claims 1 to 3, wherein the flange protruding portion has a tongue portion protruding from at least one of: (C) a portion corresponding to the top plate portion of the second member; (D) a portion corresponding to the vertical wall portion of the second member.

5. A press-molding blank according to any one of claims 1 to 4, wherein the part is an automobile part.

6. A press-molded 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 standing wall portion connected to the top plate portion, and a portion where the second member is connected to the first member so as to abut against it, wherein the connected portion of the part is formed by a blank obtained by partially overlapping a first partial blank corresponding to the first member and a second partial blank corresponding to the second member, wherein the first member has a boss-like protrusion at a portion corresponding to the standing wall portion of the first member where the second member is connected, and the second member has an end flange portion at an end corresponding to the portion where it is connected to the first member, and wherein at the overlapping portion which is the partially overlapping portion, either one or both of (A) the boss-like protrusion of the first member and the second member, and (B) the end flange portion of the second member and the standing wall portion of the first member are joined, and the portion surrounded by the boss-like protrusion of the first member is hollow.

7. A press-molded part as described in claim 6, wherein the boss-shaped protrusion has a notch near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the standing wall portion of the second member, and the depth of the notch is shorter than the width of the boss-shaped protrusion.

8. A press-molded part as described in claim 6 or 7, wherein the end flange portion has a recess near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the upright wall portion of the second member, and the depth of the recess is shorter than the width of the end flange portion.

9. A press-molded part according to any one of claims 6 to 8, wherein the end flange portion has a protruding tongue portion on at least one of: (C) a portion corresponding to the top plate portion of the second member; (D) a portion corresponding to the standing wall portion of the second member; and the tongue portion and the first member are joined together.

10. The press-molded part according to any one of claims 6 to 9, wherein the part is an automotive part.

11. A method for manufacturing a part in which a first member extending in a first direction and a second member extending in a second direction intersecting the first direction each have a top plate portion and at least one standing wall portion connected to the top plate portion, and the second member has a portion connected to the first member so as to abut against it, comprising: preparing a first partial blank corresponding to the first member and a second partial blank corresponding to the second member corresponding to the connected portion of the part; forming an opening in the first partial blank corresponding to the portion corresponding to the standing wall portion of the first member where the second member connects, and a boss protrusion that becomes a boss-shaped protrusion at an end along the opening; forming a flange protrusion that becomes an end flange at an end corresponding to the portion connected to the first member in the second partial blank; partially overlapping the first partial blank and the second partial blank; and at the overlapping portion which is the partially overlapping portion, (A) the boss protrusion of the first partial blank and the portion of the second partial blank that corresponds to the top plate portion of the second member, and (B) A method for manufacturing a press-molded part, comprising: joining one or both of a portion of the first partial blank corresponding to the upright wall portion of the first member and a portion of the flange protrusion of the second partial blank corresponding to the top plate portion of the second member to form an integrated blank; press-molding the integrated blank; and then joining the unjoined portions of the overlapping portions.

12. A method for manufacturing a press-molded part as described in claim 11, wherein the boss protrusion has a notch near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the standing wall portion of the second member, and the depth of the notch is shorter than the width of the boss protrusion.

13. A method for manufacturing a press-molded part as described in claim 11 or 12, wherein the flange protrusion has a recess near the boundary between the portion corresponding to the top plate portion of the second member and the portion corresponding to the vertical wall portion of the second member, and the depth of the recess is shorter than the width of the flange protrusion.

14. A method for manufacturing a press-molded part according to any one of claims 11 to 13, characterized in that the flange protrusion has a protruding tongue portion on at least one of: (C) a portion corresponding to the top plate portion of the second member; (D) a portion corresponding to the standing wall portion of the second member; and the tongue portion of the second partial blank and the first member are joined after the press molding.

15. The method for manufacturing a press-molded part according to any one of claims 11 to 14, wherein the part is an automobile part.

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