Impact absorbing member for automobile door, automobile door, blank, and method for manufacturing impact absorbing member for automobile door

Abstract

This impact-absorbing member for an automobile door is molded from a blank which is a monolithic blank or a tailored blank. The impact-absorbing member for an automobile door comprises a coupling-band portion extending in a first direction, and at least three coupled portions one end of each of which is connected to the coupling-band portion and which extend in a second direction transverse to the first direction. The coupled portions include an impact-absorbing location that is a closed-cross section structure.

Description

[Technical Field]

[0001] The present invention relates to an impact absorbing component for an automobile door, an automobile door, a blank, and a method for manufacturing an impact absorbing component for an automobile door. This application claims priority based on Japanese Patent Application No. 2022-107800, filed on July 4, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, the use of high-strength steel sheets for automotive exterior panels has been considered. By using high-strength steel sheets, the thickness of the steel sheets can be reduced, thereby reducing the weight of automotive exterior materials. However, because the tensile rigidity of the exterior material depends on the plate thickness, reducing the plate thickness results in insufficient tensile rigidity. In other words, if the plate thickness is reduced, the exterior material will be easily deformed when pressed by hand.

[0003] Patent Document 1 discloses a technology that enables weight reduction without reducing the tensile rigidity or impact resistance of exterior panels by arranging impact absorbing members vertically and horizontally inside the exterior panels. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 021422 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology disclosed in Patent Document 1 requires a large number of parts because multiple impact absorbing members are press-molded separately. Also, it is necessary to prepare press dies with different shapes for each inner surface shape of the portion where the exterior panel is attached. Furthermore, when welding the separate impact absorbing members to the exterior panel one by one, they must be positioned one by one before welding, which requires a large number of work steps and leads to increased manufacturing costs.

[0006] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an impact absorbing member for automobile doors, an automobile door, a blank, and a method for manufacturing an impact absorbing member for automobile doors that can exhibit excellent tensile rigidity and impact resistance performance at low cost. [Means for solving the problem]

[0007] Specific embodiments of the present invention are as follows.

[0008] (1) A first aspect of the present invention is an impact absorbing component for an automobile door formed from a blank that is a single piece blank or a tailored blank in which a plurality of blank steel sheets, each having at least one of different thickness and strength, or the same thickness and strength, are integrally connected, the impact absorbing component having a connecting band portion extending in a first direction and at least three connected portions, each having one end connected to the connecting band portion and extending in a second direction intersecting the first direction, the connected portions being: The edges of the two top surfaces of the connected part are in contact, joined, or formed facing each other with a gap of 3 mm or less. It has a shock absorbing section with a closed cross-section structure. (2) In the impact absorbing member for an automobile door described in (1) above, the blank may be a tailored blank, and the connecting belt portion and the connected portion may be integrally connected at a joint portion. (3) In the impact absorbing member for automobile doors described in (2) above, the connectable portion may have an overlapping surface that is overlapped with a part of the connecting belt portion, and the joint portion may be formed on the overlapping surface, so that the connecting belt portion and the connectable portion are connected as an integral unit. (4) In the impact absorbing component for an automobile door according to (2) or (3) above, the joint may be a welded portion, and the welded portion may not have a HAZ softened portion. (5) In the impact absorbing member for an automobile door according to any one of (1) to (4) above, the connected portion may have a tensile strength of 1100 MPa or more. (6) In the impact absorbing member for an automobile door according to any one of (1) to (5) above, the connected portion may have a Vickers hardness of 350 HV or more.

[0009] (7) A second aspect of the present invention is an automobile door having an impact absorbing component for an automobile door described in any one of (1) to (6) above and an exterior panel to which the impact absorbing component for an automobile door is attached. (8) In the automobile door described in (7) above, the automobile door impact absorbing member may be attached to a reinforcing member. (9) In the automobile door described in (8) above, the reinforcing member may have an open cross section perpendicular to its extension direction, and the connecting belt portion of the automobile door impact absorbing member may be assembled to the reinforcing member to form a closed cross section structure.

[0010] (10) A third aspect of the present invention is a device having a connecting band portion extending in a first direction and at least three connected portions each having one end connected to the connecting band portion and extending in a second direction intersecting the first direction, The edges of the two top surfaces of the connected part are in contact, joined, or formed facing each other with a gap of 3 mm or less. A blank for forming an impact-absorbing component for an automobile door having an impact-absorbing portion with a closed cross-sectional structure includes a connecting band portion-forming region extending in the first direction and formed into the connecting band portion, and at least three connectable portion-forming regions each having one end connected to the connecting band portion-forming region and extending in the second direction and formed into the at least three connectable portions, and the blank is a single piece blank or a tailored blank formed by integrally connecting multiple blank steel sheets having at least one of different thickness and strength, or the same thickness and strength. (11) The blank described in (10) above may be the tailored blank, and the connecting band portion forming region and the connected portion forming region may be integrally connected at a joint. (12) In the blank described in (11) above, the connecting portion forming area may have an overlapping surface forming area that is overlapped with a part of the connecting band portion forming area, and the joint may be formed on the overlapping surface, so that the connecting band portion forming area and the connecting portion forming area are connected together at the joint. (13) In the blank according to any one of (10) to (12) above, a notch may be formed in the vicinity of the location where the connecting band portion forming region and the connected portion forming region are connected.

[0011] (14) A fourth aspect of the present invention is a device having a connecting band portion extending in a first direction and at least three connectable portions each having one end connected to the connecting band portion and extending in a second direction intersecting the first direction, wherein the connectable portions are: The edges of the two top surfaces of the connected part are in contact, joined, or formed facing each other with a gap of 3 mm or less. a connecting band portion-forming region extending in the first direction and formed into the connecting band portion; and at least three connected portion-forming regions having one end connected to the connecting band portion-forming region, extending in the second direction, and formed into the at least three connected portions; the blank being a one-piece blank or a tailored blank formed by integrally connecting a plurality of blank-forming steel sheets, each having at least one of different thickness and strength, or the same thickness and strength; and a second step of press-forming the intermediate press-formed product to obtain the automobile door impact absorbing member. In the second step, if the blank is the one-piece blank, the intermediate press-formed product is press-formed in a state where it is heated to a temperature of not less than Ac3. In the second step, if the blank is the tailored blank, the intermediate press-formed product is press-formed in a state where it is heated to a temperature of not less than Ac3. (15) In the manufacturing method of an impact absorbing member for an automobile door described in (14) above, the blank may be a tailored blank, and the connecting band portion forming area and the connected portion forming area may be integrally connected at a joint. (16) In the manufacturing method of an impact absorbing member for an automobile door described in (15) above, the connecting portion forming area may have an overlapping surface forming area that is overlapped with a part of the connecting belt portion forming area, and the joint may be formed on the overlapping surface, so that the connecting belt portion forming area and the connecting portion forming area are connected integrally at the joint. (17) In the manufacturing method of an impact absorbing member for an automobile door described in (15) or (16) above, in the second step, press molding may be performed in a state in which the intermediate press-molded product is heated to a temperature of Ac3 point or higher. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an impact absorbing member for an automobile door, an automobile door, a blank, and a method for manufacturing an impact absorbing member for an automobile door that can exhibit excellent tensile rigidity and impact resistance at low cost. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing the structure of an automobile door to which an impact absorbing member according to a first embodiment of the present invention is attached. [Figure 2] FIG. 2 is a schematic diagram showing a cross section taken along the dashed dotted line II′ in FIG. [Figure 3] 1 is a schematic view of an impact absorbing member according to a first embodiment, as viewed from the vehicle interior side. [Figure 4] FIG. 2 is a schematic diagram showing the dimensions of a test piece. [Figure 5] 2 is a schematic diagram showing a cross section taken along the dashed line II-II' in FIG. 3. FIG. [Figure 6] FIG. 4 is an enlarged view of a portion A1 shown in FIG. [Figure 7] 3A to 3C are diagrams illustrating a process for manufacturing the impact absorbing member according to the first embodiment. [Figure 8] FIG. 2 is a schematic diagram showing a one-piece blank for manufacturing the impact absorbing member according to the first embodiment. [Figure 9] 8. FIG. 9 is a schematic diagram showing a state in which a one-piece blank shown in cross section along the dashed dotted line III-III′ in FIG. 8 is placed in a first mold. [Figure 10] 10 is a schematic diagram showing a cross section taken along the dashed dotted line IV-IV' in FIG. 9. FIG. [Figure 11] 11 is a schematic view showing a state in which the upper die of the first die shown in FIG. 10 has been lowered to the bottom dead center. FIG. [Figure 12]FIG. 2 is a schematic diagram showing a state in which a member molded in a first mold is placed in a second mold. [Figure 13] 13 is a schematic diagram showing a cross section taken along the dashed dotted line VV' in FIG. 12. FIG. [Figure 14] 14 is a schematic view showing a state in which the upper die of the second die shown in FIG. 13 has been lowered to the bottom dead center. FIG. [Figure 15] FIG. 10 is a schematic diagram showing the state in which the intermediate press-formed product is placed in a third mold. [Figure 16] 16 is a schematic diagram showing a cross section taken along the dashed dotted line VI-VI' in FIG. 15. [Figure 17] 17 is a schematic view showing a state in which the upper die of the third die shown in FIG. 16 has been lowered to the bottom dead center. FIG. [Figure 18] FIG. 4 is a schematic view showing an impact absorbing member according to a second embodiment of the present invention. [Figure 19] FIG. 19 is an enlarged view of a portion A2 shown in FIG. [Figure 20] 10A to 10C are diagrams illustrating a process for manufacturing an impact absorbing member according to a second embodiment. [Figure 21] FIG. 10 is a schematic diagram showing a tailored blank for manufacturing an impact absorbing member according to a second embodiment. [Figure 22] FIG. 10 is a schematic view showing an impact absorbing member according to a third embodiment of the present invention. [Figure 23] FIG. 23 is an enlarged view of a portion A3 shown in FIG. 22. [Figure 24] FIG. 10 is a schematic view showing a blank for manufacturing an impact absorbing member according to a third embodiment. [Figure 25] FIG. 10 is a schematic diagram showing a modified example of the blank. [Figure 26] 26 is a partially enlarged view of an impact absorbing member formed from the blank shown in FIG. 25. [Figure 27] 1 is a perspective view showing the structure of an automobile door to which a horizontally extending reinforcing member is further attached. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, the present invention will be described in detail based on embodiments. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0015] In the following description, "integrally connected" means that separate members are connected to each other by welding or the like. For example, when two blank steel plates are joined by lap welding (spot welding, laser welding, etc.), it is expressed as "two blank steel plates are integrally connected." Furthermore, a blank in which multiple blank steel plates, which have at least one of different thickness and strength, or the same thickness and strength, are integrally connected in this way, is sometimes called a tailored blank. A tailored blank is considered to be a single blank. "Connected in a continuous manner" means that different parts of a single member are connected in a continuous manner. For example, a T-shaped blank obtained by punching a single plate material in a plan view is expressed as having "two linear parts connected in a continuous manner." A single blank connected in a continuous manner in this way is sometimes called a one-piece blank.

[0016] (First embodiment) Hereinafter, an impact absorbing member 10 for an automobile door (hereinafter referred to as impact absorbing member 10) according to a first embodiment of the present invention will be described. The impact absorbing member 10 according to this embodiment is a member that is manufactured by press forming a one-piece blank 100 made of steel, and is attached to an automobile door 1.

[0017] The automobile door 1 is a front door disposed on the side of the automobile. 1 is a perspective view showing the structure of an automobile door 1 to which an impact absorbing member 10 is attached, and shows the automobile door 1 as viewed from outside the automobile. For ease of explanation, an exterior panel 1a, which will be described later, is not shown in FIG. FIG. 2 is a schematic diagram showing a cross section taken along the dashed line II' in FIG.

[0018] As shown in FIGS. 1 and 2, the automobile door 1 includes an exterior panel 1a, a reinforcing member 1b, and an interior panel 1c.

[0019] For the exterior panel 1a of the automobile door 1, it is preferable to use a high-strength steel plate having a tensile strength of 340 MPa or more for the purpose of reducing weight. Moreover, from the viewpoint of weight reduction, the thickness of the exterior panel 1a is preferably 0.6 mm or less. In order to reduce weight, it is preferable that the thickness of the exterior panel 1a is as thin as possible, but this reduces the tensile rigidity. If the thickness of the exterior panel 1a is 0.3 mm or less, the impact absorbing member 10 must be provided over a wide area to ensure tensile rigidity, which leads to an increase in weight. Therefore, it is preferable that the thickness of the exterior panel 1a is 0.3 mm or more.

[0020] 1 and 2, the reinforcing member 1b extends horizontally (in the front-to-rear direction of the vehicle in this embodiment) between the exterior panel 1a and the interior panel 1c of the automobile door 1. The reinforcing member 1b is required to have high bending rigidity in order to absorb the impact in the event of a side collision and to reinforce the vicinity of the opening for raising and lowering the window glass. 2, reinforcing member 1b has a hat-shaped open cross section. That is, reinforcing member 1b has a top plate portion 1b1, a pair of side wall portions 1b2 that are bent from and connected to the end of top plate portion 1b1, and a pair of flange portions 1b3 that are bent from and connected to the end of side wall portion 1b2. The reinforcing member 1b is attached to the automobile door 1 in such a manner that the top plate portion 1b1 faces the interior panel 1c. The reinforcing member 1b may have a joining member that is welded to connect the pair of flange portions 1b3 together. In this case, the reinforcing member 1b has a closed cross-sectional structure with an axis in the horizontal direction, thereby further increasing the bending rigidity. The reinforcing member 1b can be made of various materials such as steel, stainless steel, aluminum, aluminum alloy, and CFRP (carbon fiber reinforced plastic).

[0021] 3 is a schematic diagram of the impact absorbing member 10 when viewed from the inside of the vehicle toward the outside. As shown in FIG. 3, the impact absorbing member 10 according to this embodiment has a first connecting belt part 11, three connected parts 13, and a second connecting belt part 15. As shown in Figure 1, the impact absorbing member 10 is attached along the inner surface of the exterior panel 1a of the automobile door 1 in a position in which the first connecting belt portion 11 extends in an approximately horizontal direction and the connected portion 13 extends in an approximately vertical direction (in the vehicle height direction in this embodiment). In the following description, the direction in which the first connecting belt part 11 extends, i.e., the longitudinal direction of the first connecting belt part 11, is referred to as the first direction α. ​​The direction in which the connectable part 13 extends, i.e., the direction intersecting with the first direction α, is referred to as the second direction β.

[0022] The thickness of the impact absorbing member 10 is preferably 0.6 mm or more and 2.0 mm or less. When the thickness of the impact absorbing member 10 is 2.0 mm or less, it is possible to reduce the weight of the impact absorbing member 10. The thickness of the impact absorbing member 10 is more preferably 1.2 mm or less. On the other hand, if the plate thickness of the impact absorbing member 10 is 0.6 mm or more, the impact absorbing performance of the impact absorbing member 10 can be ensured and the bending rigidity of the first connecting belt portion 11 can be sufficiently ensured, making it easier to attach the impact absorbing member 10 to the automobile door 1.

[0023] From the viewpoint of weight reduction, it is preferable that the impact absorbing member 10 has a tensile strength measured at the connected portion 13 of 1100 MPa or more. Here, the tensile strength is the tensile strength measured from a test piece taken from the connected portion 13, excluding portions where the strength has locally changed, such as bent portions and welded portions. Test specimens with the dimensions shown in Figure 4 are used. The thickness of the test specimens is the same as that of the specimens taken from the components. Tensile strength is measured in accordance with JIS Z 2241 (2011), and a tensile test is carried out at a tension speed (crosshead displacement speed) of 10 mm / min.

[0024] Furthermore, in the impact absorbing member 10, from the viewpoint of weight reduction, it is preferable that the Vickers hardness measured at the connected portion 13 is 350 HV or more. Here, the Vickers hardness is measured at five points at least 10 mm away from the connected portion 13, excluding areas where the hardness has changed locally, such as bent deformed areas and welded areas, in accordance with the Vickers hardness test method specified in JIS Z 2244-1:2020. Vickers hardness is measured at five points on the cut surface, spaced 1 / 4 of the plate thickness from the surface in the plate thickness direction, with a load (test force) of 9.8 N and spaced 1.0 mm or more apart. The average value of the Vickers hardness measured at these five points is defined as the Vickers hardness of the connected portion 13 .

[0025] As will be described later, the manufacturing method of the impact absorbing member 10 includes a second step of hot stamping. Therefore, the impact absorbing member 10 generally has a martensite structure.

[0026] The first connecting band portion 11 is a portion that connects together the three connected portions 13. The first connecting band portion 11 is attached to the automobile door 1 by welding or the like.

[0027] As shown in FIGS. 1 and 2, the first connecting belt portion 11 is preferably attached by welding so as to connect a pair of flange portions 1b3 of the reinforcing member 1b having a hat-shaped open cross section. As described above, the reinforcing member 1b can have a closed cross-sectional structure by attaching a joining member that is welded to connect a pair of flange portions 1b3, thereby achieving the effect of increasing bending rigidity; however, in this case, the number of parts increases. On the other hand, by configuring the first connecting belt portion 11 to connect the pair of flange portions 1b3 together by welding, it is possible to form a closed cross-sectional structure and increase the bending rigidity without increasing the number of parts, which makes it possible to further reduce the weight of the automobile door 1 and to manufacture it at lower cost. Furthermore, the first connecting belt portion 11 may be attached to only a part of the reinforcing member 1b, for example, only the lower end flange portion 1b3 (if a joining member is attached, the portion of the joining member attached to the lower end flange portion 1b3).

[0028] The connected portion 13 is a portion extending from the edge 11a of the first connecting belt portion 11 in the width direction (direction perpendicular to the first direction α) along the second direction β. As shown in FIG. 3, the connected portion 13 has an impact absorbing portion 13a, a first transition portion 13b, and a second transition portion 13c.

[0029] FIG. 5 is a schematic diagram showing a cross section taken along the dashed line II-II' in FIG. 3, that is, a cross section of the impact absorbing part 13a perpendicular to the second direction β. 5, the shock absorbing part 13a has a closed cross-sectional structure. That is, the shock absorbing part 13a has a bottom surface 13a1, a pair of side wall surfaces 13a2 that are bent from the ends of the bottom surface 13a1 and connected to the bottom surface 13a1, and two top surfaces 13a3 that are bent from the ends of the side wall surfaces 13a2 and connected to the bottom surface 13a1. The edges of the two top surfaces 13a3 are in contact with or joined to each other to form a closed cross-sectional structure. In the present application, even when a gap of 3 mm or less is formed between the edges of the two top surfaces 13a3, it can be considered to be a closed cross-sectional structure. When a load is applied to the impact absorbing portion 13a from the outside of the vehicle toward the inside, the cross section of the impact absorbing portion 13a deforms in the direction in which the edges of the top surface 13a3 come into contact with each other as the impact absorbing portion 13a bends and deforms, closing the gap.

[0030] The impact absorbing portion 13a has a closed cross-sectional structure, which imparts tensile rigidity to the exterior panel 1a and increases the amount of impact absorption when the automobile door 1 receives an impact due to a collision. The cross-sectional shape may be circular, elliptical, trapezoidal, etc., but in order to further increase the shock absorption capacity, it is preferable to adopt a rectangular closed cross-sectional structure.

[0031] The shock absorbing portion 13a is provided so that the bottom surface 13a1 is at least partially joined along the inner surface of the exterior panel 1a, thereby imparting tension rigidity to the exterior panel 1a and increasing the amount of shock absorption when the automobile door 1 is subjected to a collision shock. The bottom surface 13a1 and the inner surface of the exterior panel 1a may be joined together using an adhesive such as a mastic sealer.

[0032] The impact absorbing portion 13 a is formed up to the second transition portion 13 c of the connected portion 13 , and the three second transition portions 13 c are connected to the second connecting belt portion 15 . As shown in FIG. 1, the second connecting band portion 15 is attached by welding or the like to the lower end of the interior panel 1c of the automobile door 1 in contact therewith. When the second connecting band portion 15 is not provided, the tips (lower ends) of the three connected portions 13 may be attached by abutting against the lower end of the interior panel 1c of the automobile door 1 by welding or the like.

[0033] Fig. 6 is an enlarged view of portion A1 shown in Fig. 3. As shown in Fig. 6, the first transition portion 13b extends along the second direction β from the widthwise edge 11a of the first connecting belt portion 11. The first transition portion 13b is processed so that the cross-sectional shape of the first transition portion 13b gradually approaches that of the impact absorbing portion 13a as it moves away from the first connecting belt portion 11. As shown in Figures 5 and 6, the first transition portion 13b has a bottom surface 13b1 that is continuous with and connected to the bottom surface 13a1 of the impact absorbing portion 13a, a side wall surface 13b2 that is continuous with and connected to the side wall surface 13a2 of the impact absorbing portion 13a, and a top surface 13b3 that is continuous with and connected to the top surface 13a3 of the impact absorbing portion 13a.

[0034] Since the impact absorbing member 10 according to this embodiment is a member formed from a single piece blank 100, the bottom surface 13b1 is connected to the first connecting belt portion 11. In other words, there is no physical boundary line, such as a joining mark, between the bottom surface 13b1 and the first connecting belt portion 11.

[0035] In the first transition portion 13b, the flat first connecting belt portion 11 and the shock absorbing portion 13a, which has a closed cross-sectional structure, are connected by a gradual change in cross-section, thereby suppressing the occurrence of cracks when processing the shock absorbing portion 13a.

[0036] According to the shock absorbing member 10 of this embodiment, the shock absorbing portion 13a having a closed cross-sectional structure is formed, and thus the shock absorbing member 10 can exhibit excellent tensile rigidity and shock resistance performance while being lightweight. Furthermore, since the impact absorbing member 10 is press-molded from a single blank 100, the first connecting band portion 11 and the three connectable portions 13 are connected in a continuous manner, so there is no need for a process of joining the first connecting band portion 11 and the connectable portions 13 after press molding. Furthermore, the number of parts and molds required can be reduced compared to when the first connecting belt portion 11 and the three connected portions 13 are processed separately. Furthermore, since there is no need to process the first connecting belt portion 11 and the three connected portions 13 separately and then join them by welding, cracks and the like caused by the HAZ softened portion formed during welding can also be avoided. Furthermore, when attaching the impact absorbing member 10 to the automobile door 1, the impact absorbing member 10 can be attached to the automobile door 1 as a single member, which makes the installation process simpler than if each member had to be transported, positioned, and attached separately. Therefore, according to the impact absorbing member 10 of this embodiment, it is possible to manufacture the automobile door 1 that can exhibit excellent tensile rigidity and impact resistance performance at low cost.

[0037] Next, a method for manufacturing the impact absorbing member 10 will be described. FIG. 7 is a diagram for explaining the process for manufacturing the impact absorbing member 10. As shown in FIG. The impact absorbing member 10 can be manufactured by performing a first step in which a single blank 100 is press-formed in a cold state to obtain an intermediate press-formed product 120, a second step in which this intermediate press-formed product 120 is hot-stamped, and further performing trimming as necessary.

[0038] The one-piece blank 100 can be obtained by punching out a single steel sheet for blank. FIG. 8 is a schematic diagram of a one-piece blank 100. The single-piece blank 100 has a first connecting band portion forming region 101 which is formed into a first connecting band portion 11 through a press process, three connecting portion forming regions 103 which are formed into three connecting portions 13 through a press process, and a second connecting band portion forming region 105 which is formed into a second connecting band portion 15 through a press process. In addition, the connected portion forming region 103 has an impact absorbing portion forming region 103a which is formed into an impact absorbing portion 13a through a press process, a first transition portion forming region 103b which is formed into a first transition portion 13b through a press process, and a second transition portion forming region 103c which is formed into a second transition portion 13c through a press process.

[0039] Since the one-piece blank 100 is obtained by punching out a single blank steel plate, the first connecting band portion forming region 101, the connected portion forming region 103, and the second connecting band portion forming region 105 are connected to each other in a continuous line.

[0040] The thickness of the one-piece blank 100 is preferably 0.6 mm or more and 2.0 mm or less, similar to the thickness of the impact absorbing member 10 .

[0041] The pressure of the one-piece blank 100 is preferably 800 MPa or less to prevent cracks from occurring in the first step by cold pressing.

[0042] (first step) In the first step, the one-piece blank 100 is cold press-formed to obtain an intermediate press-formed product 120. In the example described here, the intermediate press-formed product 120 is manufactured by two cold press-forming steps. Cold press forming means that press forming is carried out at room temperature.

[0043] (Molding with the first mold) First, a first mold 1000 is used to form a one-piece blank 100 into a member 110 . Specifically, the region 103 of the one-piece blank 100 where the connected portion is to be formed is formed into the region 113 of the member 110 where the connected portion is to be formed.

[0044] FIG. 9 is a schematic diagram showing a state in which the one-piece blank 100 shown in cross section along the dashed line III-III' in FIG. 8 is placed in the first mold 1000. In FIG. FIG. 10 is a schematic diagram showing a cross section taken along the dashed line IV-IV' in FIG. As shown in FIGS. 9 and 10, the first mold 1000 is composed of a lower mold 1100 and an upper mold 1200.

[0045] The lower mold 1100 has a lower mold body 1110 and a pad 1120. The pad 1120 is connected to a pressure device (not shown) disposed below the lower mold body 1110, for example, so that the pad 1120 is movable up and down independently of the lower mold body 1110. The lower die body 1110 has a placement surface 1111 on which the one-piece blank 100 is placed, and a groove portion 1112 formed so as to be recessed from the placement surface 1111. The pad 1120 is provided in the groove 1112 of the lower die body 1110 so that the top surface 1120U of the pad 1120 faces the lower surface of the one-piece blank 100. As shown in Figure 9, the pad 1120 has a structure in which a first portion 1121 for placing the first connecting band portion forming region 101 of the one-piece blank 100 and a second portion 1123 for placing the connected portion forming region 103 of the one-piece blank 100 are integrally formed.

[0046] The upper mold 1200 has an upper mold body 1210 . The upper die body 1210 has a convex shape corresponding to the groove 1112 of the lower die body 1110. The upper die body 1210 is provided so that its bottom surface 1210D faces the top surface of the one-piece blank 100. The upper end of the upper mold body 1210 is connected to a drive mechanism (not shown) so that it can move up and down freely. As shown in Figure 9, the upper mold body 1210 has a structure in which a first portion 1211 facing the first connecting band portion forming region 101 of the one-piece blank 100 and a second portion 1213 facing the connected portion forming region 103 of the one-piece blank 100 are integrally formed.

[0047] FIG. 11 is a schematic diagram showing a state in which the upper die 1200 of the first die 1000 shown in FIG. 10 has been lowered to the bottom dead center. As shown in FIG. 11, the upper die body 1210 is lowered to the bottom dead center, whereby the one-piece blank 100 can be press-formed into the member 110. As the upper die body 1210 is lowered, the widthwise central portion of the shock absorbing portion forming region 103a of the one-piece blank 100 is sandwiched between the bottom surface 1210D of the upper die body 1210 and the top surface 1120U of the pad 1120. Then, as the upper die body 1210 is further lowered from this state, the pad 1120 follows and descends, and press forming proceeds with the one-piece blank 100 sandwiched between the top surface 1120U and the bottom surface 1210D, and the member 110 is formed.

[0048] (Molding with the second mold) Next, the member 110 press-molded by the first mold is molded into an intermediate press-molded product 120 using a second mold 2000 .

[0049] FIG. 12 is a schematic diagram showing a state in which the member 110 is placed in a second mold 2000. As shown in FIG. FIG. 13 is a schematic diagram showing a cross section taken along the dashed line VV' in FIG. As shown in FIGS. 12 and 13, the second mold 2000 is composed of a lower mold 2100 and an upper mold 2200.

[0050] The lower mold 2100 has a lower mold body 2110. The lower mold body 2110 has a top surface 2110U on which the member 110 is placed. As shown in Figure 12, the lower mold body 2110 has a structure in which a first portion 2111 for placing the bottom surface of the first connecting band portion forming region 111 of the member 110 and a second portion 2113 for placing the bottom surface of the connected portion forming region 113 of the member 110 are integrally formed.

[0051] 12, the upper mold 2200 has an upper mold body 2210 and a pad 2220. The pad 2220 is connected to a pressure device (not shown) that is arranged above the upper mold body 2210, for example, so that the pad 2220 is movable up and down independently of the upper mold body 2210.

[0052] 13, the upper mold body 2210 has an inverted U-shaped recess formed by an inclined surface 2211, a vertical wall surface 2212, and a ceiling surface 2213. The upper end of the upper mold body 2210 is connected to a drive mechanism (not shown), so that it can move up and down freely. The upper mold body 2210 is provided above the second portion 2113 of the lower mold body 2110. In other words, it is installed above the position of the coupled portion formation region 113 of the member 110.

[0053] The pad 2220 is provided above the first portion 2111 of the lower mold body 2110. In other words, it is installed above the position of the first connecting belt portion forming region 111 of the member 110.

[0054] FIG. 14 is a schematic diagram showing a state in which the upper mold 2200 of the second mold 2000 shown in FIG. 13 has been lowered to the bottom dead center. With the first connecting band portion forming region 111 of the member 110 clamped between the first portion 2111 of the lower mold body 2110 and the pad 2220, the upper mold body 2210 is lowered to the bottom dead center, whereby the member 110 can be press-molded into an intermediate press-molded product 120. As the upper mold body 2210 is lowered, the edge of the "portion corresponding to the top surface 13a3" of the member 110 comes into contact with the inclined surface 2211 of the upper mold body 2210. As the upper die body 2210 is further lowered, the edge of the "portion corresponding to the top surface 13a3" slides along the inclined surface 2211 while press-forming progresses, and the intermediate press-formed product 120 is formed.

[0055] (Second process) In the second step, the intermediate press-formed product 120, which has been heated to a temperature equal to or higher than the Ac3 point, is molded into the impact absorbing member 10 using a third mold 3000.

[0056] The intermediate press-formed product 120 can be heated by a heating furnace or by electrical heating. However, heating by a heating furnace is preferred because temperature control is easy and even complex shapes can be heated uniformly. Examples of heating furnaces include gas heating furnaces, electric heating furnaces, infrared heating furnaces, and high-frequency heating furnaces. The Ac3 point is the temperature at which the steel material is austenitized, and is expressed, for example, by the following formula. Ac3 point (℃)=910-203×√C(mass%)-30×Mn(mass%)-11×Cr(mass%)+44.7×Si(mass%)+400×Al(mass%) +700×P(mass%)-15.2×Ni(mass%)-20×Cu(mass%)+400×Ti(mass%)+104×V(mass%)+31.5×Mo(mass%) In the above formula, C, Mn, Cr, Si, Al, P, Ni, Cu, Ti, V, and Mo are the contents of the chemical components of the steel that constitutes the coupled portion formation region 103.

[0057] FIG. 15 is a schematic diagram showing a state in which the intermediate press-formed product 120 is placed in the third mold 3000. As shown in FIG. FIG. 16 is a schematic diagram showing a cross section taken along the dashed line VI-VI' in FIG. As shown in FIGS. 15 and 16, the third mold 3000 is composed of a lower mold 3100 and an upper mold 3200.

[0058] The lower mold 3100 has a lower mold body 3110. The lower mold body 3110 has a recess having a shape corresponding to the shock absorbing member 10. As shown in Figure 15, the lower mold body 3110 has a structure in which a first portion 3111 for placing the first connecting band portion forming region 121 of the intermediate press-formed product 120 and a second portion 3113 above which the connected portion forming region 123 of the intermediate press-formed product 120 is positioned are integrally formed.

[0059] The upper mold 3200 has an upper mold body 3210 and a pad 3220 . The upper mold body 3210 has a convex portion 3211 having a shape corresponding to the concave portion of the lower mold body 3110 . 15 , the pad 3220 is placed above a portion of the intermediate press-formed product 120 that corresponds to the first connecting band portion forming region 121. The pad 3220 is connected to a pressure device (not shown) that is arranged above the upper mold body 3210, for example, so that the pad 3220 is movable up and down independently of the upper mold body 3210. The lower mold 3100 and the upper mold 3200 are equipped with a cooling mechanism that uses a cooling medium such as water cooling.

[0060] FIG. 17 is a schematic diagram showing a state in which the upper mold 3200 of the third mold 3000 shown in FIG. 16 has been lowered to the bottom dead center. The intermediate press-formed product 120, which has been preheated to a temperature above the Ac3 point, is placed on the lower die 3100, and the upper die 3200 is lowered to the bottom dead center, thereby obtaining the shock-absorbing member 10. Since the lower mold 3100 and the upper mold 3200 are equipped with a built-in cooling mechanism, the intermediate press-formed product 120 in a heated state can be more efficiently hardened by holding it at the bottom dead center during press forming. The cooling of the formed product while holding it at bottom dead center can be performed by a mold cooled by a cooling medium, or by direct cooling by a cooling medium supplied from the forming surface of the mold. Direct cooling by a cooling medium allows for more efficient quenching. The mold cooling mechanism may be omitted. After the press forming is completed, trimming may be performed as necessary to cut off unnecessary portions, and the resulting member may be used as the impact absorbing member 10.

[0061] According to the method for manufacturing the impact absorbing member 10 using the one-piece blank 100 as described above, there is no need to weld the first connecting belt portion 11 and the connected portion 13 together after press molding. Furthermore, a plurality of impact absorbing portions 13a can be molded as a single impact absorbing member 10 and assembled to the automobile door 1. Therefore, the impact absorbing member 10 can be manufactured efficiently and at low cost.

[0062] Second Embodiment An impact absorbing member 20 for an automobile door (hereinafter referred to as impact absorbing member 20) according to a second embodiment of the present invention will be described below. The impact absorbing member 10 of the first embodiment is a member manufactured by press molding from a single blank 100 made of steel, but the impact absorbing member 20 of the second embodiment differs from the first embodiment in that it is a member manufactured by press molding from a tailored blank 200 made of steel. For the sake of simplicity, the description overlapping with the first embodiment will be omitted.

[0063] 18 is a schematic diagram of the impact absorbing member 20. As shown in FIG. 18, the impact absorbing member 20 according to this embodiment has a first connecting belt part 21, three connected parts 23, and a second connecting belt part 25.

[0064] The preferred thickness, tensile strength, and Vickers hardness of the impact absorbing member 20 are the same as those described for the impact absorbing member 10 according to the first embodiment. However, because the impact absorbing member 20 is formed using a tailored blank 200, different thicknesses, tensile strengths, and Vickers hardnesses can be used for the first connecting belt portion 21, the three connectable portions 23, and the second connecting belt portion 25.

[0065] The impact absorbing member 20 may have a martensitic structure. More specifically, at least one of the first connecting belt portion 21, the connected portion 23, and the second connecting belt portion 25 of the impact absorbing member 20 may have a generally martensitic structure.

[0066] The first connecting belt portion 21 is a portion that is overlapped with each of the three connected portions 23 and is integrally connected at spot welds w. The first connecting belt portion 21 is attached to the automobile door 1 by welding or the like. The spot weld w is an example of a weld. From the viewpoint of workability, it is preferable to form the weld by spot welding, but the weld may be a linear weld by laser welding or plasma welding. Moreover, instead of the welded portion, a joint using a rivet or the like may be used.

[0067] The connected portion 23 is a portion that extends from the edge 21a of the first connecting belt portion 21 in the width direction (direction perpendicular to the first direction α) along the second direction β. As shown in FIG. 18, the connected portion 23 has an impact absorbing portion 23a, a first transition portion 23b, and a second transition portion 23c.

[0068] Figure 19 is an enlarged view of portion A2 shown in Figure 18. As shown in Figure 19, the first transition portion 23b extends in the second direction β from the widthwise edge 21a of the first connecting belt portion 21. The first transition portion 23b is processed so that the cross-sectional shape of the first transition portion 23b gradually approaches that of the impact absorbing portion 23a as it moves away from the first connecting belt portion 21. As shown in FIG. 19, the first transition portion 23b has a bottom surface 23b1 that is continuous with and connected to the impact absorbing portion 23a, a side wall surface 23b2, and a top surface 23b3.

[0069] In the impact absorbing member 20 according to this embodiment, an overlapping surface 23E that overlaps the first connecting belt portion 21 is connected to the end of the bottom surface 23b1. This overlapping surface 23E is connected to the first connecting belt portion 21 by a spot weld w.

[0070] In the first transition portion 23b, the flat first connecting belt portion 21 and the shock absorbing portion 23a, which has a closed cross-sectional structure, are connected by a gradual change in cross-section, thereby suppressing the occurrence of cracks when processing the shock absorbing portion 23a. Furthermore, since the overlapping surface 23E, which is continuous with and connected to the first transition portion 23b, overlaps the first connecting belt portion 21, the bending rigidity and strength of the first connecting belt portion 21 can also be increased.

[0071] According to the impact absorbing member 20 of this embodiment, the impact absorbing portion 23a having a closed cross-sectional structure is formed, and thus the impact absorbing member 20 can exhibit excellent tensile rigidity and impact resistance performance while being lightweight. Furthermore, since the impact absorbing member 20 is press-molded from a tailored blank 200, the first connecting band portion 21 and the three connectable portions 23 are connected as a single unit, so there is no need for a process of joining the first connecting band portion 21 and the connectable portions 23 after press molding. Furthermore, the number of parts and molds required can be reduced compared to when the first connecting band portion 21 and the three connected portions 23 are processed separately. Furthermore, if hot stamping is selected in the second process described below, the HAZ-softened portion formed in the spot welded portion w in the tailored blank 200 can be reduced or eliminated by the heat input during hot stamping, thereby suppressing cracks and the like caused by the HAZ-softened portion.

[0072] In this application, the term "HAZ-softened zone" refers to a region (region of both welded members) surrounding a weld (weld line) where the metal structure has changed due to the influence of the thermal cycle during welding, resulting in a 20% or greater decrease in hardness compared to the base material. Specifically, this change in metal structure refers to a change to tempered martensite due to tempering, or a change to a mixed structure containing ferrite due to cooling from the ferrite-austenite two-phase region.

[0073] The absence of HAZ softening can be confirmed by the following procedure. First, the Vickers hardness of the base material is measured at five points 10 mm or more away from the center point of the weld (or the center line of the weld line) in accordance with the Vickers hardness test method specified in JIS Z 2244-1:2020. Specifically, on the cut surface including the weld, measurements are taken at five points 1.0 mm or more apart, at a distance of 1 / 4 of the plate thickness from the surface in the plate thickness direction, with a load (test force) of 9.8 N. The average of the Vickers hardness values ​​measured at these five points is taken as the Vickers hardness of the base material. Next, in an area within 10 mm from the center point of the weld (or the center line of the weld line), Vickers hardness is measured at a position 1 / 4 of the plate thickness from the surface in the plate thickness direction on the cut surface including the weld, in accordance with the Vickers hardness test method specified in JIS Z 2244-1:2020, with a load (test force) of 3 N and a measurement interval of 0.5 mm. In the case of overlapping, measurement is made at a position 1 / 4 of the plate thickness from the surface on the overlapping side in the plate thickness direction. If the minimum Vickers hardness value is more than 80% of the Vickers hardness of the base material, it is determined that no HAZ softening is present.

[0074] When cold pressing is selected in the second step described below, the HAZ softened portion may be reduced or eliminated by partial tempering heat treatment after spot welding (e.g., high-frequency heating, laser heating, or post-current application during spot welding). Furthermore, when attaching the impact absorbing member 20 to the automobile door 1, the impact absorbing member 20 can be attached to the automobile door 1 as a single member, which makes the installation process simpler than when each member needs to be transported, positioned, and attached separately. Therefore, the impact absorbing member 20 according to this embodiment makes it possible to manufacture the automobile door 1 that can exhibit excellent tensile rigidity and impact resistance at low cost.

[0075] Next, a method for manufacturing the impact absorbing member 20 will be described. FIG. 20 is a diagram for explaining the process for manufacturing the impact absorbing member 20. As shown in FIG. The impact absorbing member 20 can be manufactured by performing a first step in which the tailored blank 200 is press-formed in a cold state to obtain an intermediate press-formed product, a second step in which this intermediate press-formed product is cold-pressed or hot-stamped, and further performing trimming as necessary. The region to be connected in the tailored blank 200 has an overlapping surface forming region that is overlapped with a part of the connecting belt portion forming region, and the joint is formed on the overlapping surface, so that the connecting belt portion forming region and the connecting portion forming region are connected integrally at the joint. The manufacturing method of the impact absorbing member 20 is substantially the same as the manufacturing method of the impact absorbing member 10 of the first embodiment, except that a tailored blank 200 is used instead of a one-piece blank 100, so detailed explanation will be omitted.

[0076] When using the tailored blank 200, by selecting cold pressing in the second process, it is possible to use a high-strength steel plate only in the impact absorbing portion 23a, for example. Therefore, it is possible to manufacture the automobile door 1 that can exhibit excellent tensile rigidity and impact resistance at a lower cost. On the other hand, when a tailored blank 200 is used, by selecting hot stamping in the second step, it is possible to eliminate the HAZ softened portion without performing tempering heat treatment.

[0077] The tailored blank 200 can be obtained by integrating and connecting a plurality of blank steel plates at spot welds w. FIG. 21 is a schematic diagram of a tailored blank 200. The tailored blank 200 has a first connecting band portion forming region 201 which is formed into the first connecting band portion 21 through a press process, three connecting portion forming regions 203 which are formed into three connecting portions 23 through a press process, and a second connecting band portion forming region 205 which is formed into the second connecting band portion 25 through a press process. In addition, the connected portion forming region 203 has an impact absorbing portion forming region 203a which is formed into an impact absorbing portion 23a through a press process, a first transition portion forming region 203b which is formed into a first transition portion 23b through a press process, and a second transition portion forming region 203c which is formed into a second transition portion 23c through a press process.

[0078] The thickness and strength of the tailored blank 200 may be within the same range as the thickness and strength of the one-piece blank 100 described in the first embodiment. However, because the tailored blank 200 is obtained by overlapping multiple blank steel plates, different plate thicknesses, strengths, and chemical compositions can be used between the first connecting belt portion forming region 201, the three connectable portion forming regions 203, and the second connecting belt portion forming region 205. When an overlapping configuration is used, the tolerance for dimensional error in the outer shape of each region before joining can be wider than when a butt joint configuration is used. Furthermore, when an overlapping configuration is used, spot welding can be used, so the impact absorbing member 10 can be manufactured efficiently and at low cost.

[0079] According to the method for manufacturing the impact absorbing member 20 using the tailored blank 200 as described above, there is no need to weld the first connecting belt portion 21 and the connected portion 23 together after press molding. Furthermore, a plurality of impact absorbing portions 23a can be molded as a single impact absorbing member 20 and attached to the automobile door 1. Therefore, the impact absorbing member 20 can be manufactured efficiently and at low cost. The tailored blank 200 can be obtained by punching out approximately rectangular blank steel plates corresponding to the first connecting belt portion forming region 201, the connected portion forming region 203, and the second connecting belt portion forming region 205, and then joining them together. This reduces the amount of scrap of blank steel plates. This improves yield and enables the impact absorbing member 20 to be manufactured at even lower cost.

[0080] In the second embodiment, a tailored blank 200 joined at the overlapping portion is given as an example, but it is also possible to use a tailored blank joined by welding the edges of blank steel plates together using laser welding, plasma welding, etc. Furthermore, in the tailored blank 200, the joint (welded portion w) is located at the boundary between the first connecting belt portion 21 and the connected portion 23, but this is not limitative.

[0081] (Third embodiment) An impact absorbing member 30 for an automobile door (hereinafter referred to as impact absorbing member 30) according to a third embodiment of the present invention will be described below. The impact absorbing members 10, 20 according to the first and second embodiments are formed using a one-piece blank 100 or a tailored blank 200 in which the coupled portion forming regions 103, 203 are linear. The basic configuration of the impact absorbing member 30 of the third embodiment is the same as that of the impact absorbing members 10 and 20 of the first and second embodiments, but differs in that it uses a blank 300 having a shape in which a notch C is formed. For the sake of simplicity, the description overlapping with the first and second embodiments will be omitted.

[0082] 22 is a schematic diagram of the impact absorbing member 30. As shown in FIG. 22, the impact absorbing member 30 according to this embodiment has a first connecting belt part 31, three connected parts 33, and a second connecting belt part 35.

[0083] The first connecting band portion 31 is a portion that integrally connects the three connected portions 33 at spot welds w. The first connecting band portion 31 is attached to the automobile door 1 by welding or the like.

[0084] The connected portion 33 is a portion extending from the edge 31a of the first connecting belt portion 31 in the width direction (direction perpendicular to the first direction α) along the second direction β. As shown in FIG. 22, the connected portion 33 has an impact absorbing portion 33a, a first transition portion 33b, and a second transition portion 33c.

[0085] Fig. 23 is an enlarged view of part A3 shown in Fig. 22. As shown in Fig. 23, the first transition region 33b extends from the widthwise edge 31a of the first connecting belt portion 31 along the second direction β. As shown in FIG. 23, the first transition portion 33b has a bottom surface 33b1 that is continuous with and connected to the bottom surface of the impact absorbing portion 33a. That is, the first transition portion 33b connects the first connecting belt portion 31 and the bottom surface of the impact absorbing portion 33a in a flat manner.

[0086] In the first transition portion 33b, the flat first connecting belt portion 31 and the flat bottom surface of the impact absorbing portion 33a, which has a closed cross-sectional structure, are connected without significantly changing the cross-sectional shape, thereby suppressing the occurrence of cracks when processing the impact absorbing portion 33a. Furthermore, since the length of the first transition portion 33b in the second direction β can be reduced, the length of the shock absorbing portion 33a in the second direction β can be increased, thereby increasing the amount of shock absorption by the shock absorbing portion 33a.

[0087] Therefore, the impact absorbing member 30 according to this embodiment makes it possible to manufacture the automobile door 1 that is capable of exhibiting excellent tensile rigidity and impact resistance at low cost.

[0088] The method for manufacturing the impact absorbing member 30 is substantially the same as the method for manufacturing the impact absorbing member 10 according to the first embodiment, except that a blank 300 is used instead of the one-piece blank 100, and therefore a description thereof will be omitted. The blank 300 will now be described.

[0089] FIG. 24 is a schematic diagram of the blank 300. The blank 300 has a first connecting belt portion forming region 301 which is formed into the first connecting belt portion 31 through a pressing process, three connecting portion forming regions 303 which are formed into three connecting portions 33 through a pressing process, and a second connecting belt portion forming region 305 which is formed into the second connecting belt portion 35 through a pressing process. In addition, the connected portion forming region 303 has an impact absorbing portion forming region 303a which is formed into an impact absorbing portion 33a through a press process, a first transition portion forming region 303b which is formed into a first transition portion 33b through a press process, and a second transition portion forming region 303c which is formed into a second transition portion 33c through a press process.

[0090] In the blank 300, a notch C is formed on both ends in the width direction in the first transition portion forming region 303b. By forming such a notch C, when the blank 300 is press-processed into the shock-absorbing member 30, the first transition region 33b can connect the flat first connecting belt portion 31 and the flat bottom surface of the shock-absorbing region 33a having a closed cross-sectional structure in a flat shape, thereby suppressing the occurrence of cracks when processing the shock-absorbing region 33a. Furthermore, since the length of the first transition portion 33b in the second direction β can be reduced, the length of the shock absorbing portion 33a in the second direction β can be increased, thereby increasing the amount of shock absorption by the shock absorbing portion 33a.

[0091] The notch C may be formed in the first connecting belt portion, as in a modified blank 300A shown in FIG.

[0092] According to the method of manufacturing the impact absorbing member 30 using the blank 300 having the notch C formed therein as described above in the one-piece blank 100 of the first embodiment or the tailored blank 200 of the second embodiment, there is no need to weld the first connecting belt portion 31 and the connected portion 33 after press molding. Furthermore, a plurality of impact absorbing portions 33a can be molded as a single impact absorbing member 30 and attached to the automobile door 1. Furthermore, by forming the notch C, it is possible to suppress the occurrence of cracks when processing the shock absorbing portion 33a. 26 is a partially enlarged view of the impact absorbing member 30A formed from the blank 300A shown in FIG. 25. As shown in FIG. 26, a flat portion Q is formed by folding over a portion of the first transition portion 33b at the end of the first transition portion 33b of the connected portion 33. When this flat portion Q is arranged to overlap the flange portion 1b3 of the reinforcing member 1b, the collision load applied to the impact absorbing member 10 can be efficiently supported by the reinforcing member 1b. Therefore, it is possible to manufacture the automobile door 1 that can exhibit excellent tensile rigidity and impact resistance at low cost.

[0093] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications or alterations within the scope of the technical idea of ​​the present invention, and it is understood that these also naturally fall within the technical scope of the present invention.

[0094] For example, as in the automobile door 2 shown in Fig. 27, another impact absorbing member 50 may be attached with the connected portion extending horizontally. As this impact absorbing member 50, the impact absorbing members 10, 20, and 30 described in the above embodiments may be used. Although the example shows a configuration in which the first connecting strap connects three connectable parts, the number of connectable parts may be four or more. Also, in the above embodiment, the example shows a configuration in which the upper ends of the connectable parts are connected by the first connecting strap and the lower ends are connected by the second connecting strap, but the example may show a configuration in which only one end (upper end or lower end) is connected by the first connecting strap. Furthermore, the automobile door may be not only a front door located on the side of the automobile, but also a rear door located on the side of the automobile or a back door (also called a tailgate) located at the rear of the automobile. In the above-described embodiment, steel is used as the material for the blank and the impact absorbing member, but metals such as stainless steel, aluminum, aluminum alloy, or CFRP may also be used. [Industrial Applicability]

[0095] According to the present invention, it is possible to provide an impact absorbing member for an automobile door, an automobile door, a blank, and a method for manufacturing an impact absorbing member for an automobile door that can exhibit excellent tensile rigidity and impact resistance at low cost. [Explanation of symbols]

[0096] 1. Car door 1a Exterior panel 1b Reinforcement member 1c Interior panel 10. Impact absorbing member 11 First connecting band 13 Connected part 13a Impact absorption area 13b First transition site 13c Second transition site 15 Second connection band part 23E Overlapping surface 100 Single Blank 200 Tailored Blanks

Claims

1. An impact absorbing component for an automobile door formed from a blank that is a single piece blank or a tailored blank in which a plurality of blank steel plates having different thicknesses and strengths or the same thicknesses and strengths are integrally connected, a connecting band portion extending in a first direction; At least three connected portions, one end of which is connected to the connecting band portion and which extend in a second direction intersecting the first direction; and The connected portion has a shock absorbing portion having a closed cross-sectional structure in which the edges of two top surfaces of the connected portion are in contact with, joined to, or opposed to each other with a gap of 3 mm or less.

1. A shock absorbing component for an automobile door.

2. the blank is the tailored blank, The connecting belt portion and the connected portion are integrally connected at a joint portion.

2. The shock absorbing member for an automobile door according to claim 1.

3. the connected portion has an overlapping surface that overlaps a part of the connecting belt portion, The joining portion is formed on the overlapping surface, so that the connecting band portion and the connected portion are integrally connected.

3. The shock absorbing member for an automobile door according to claim 2.

4. The joint is a welded joint, and the welded joint does not have a HAZ softened zone.

3. The shock absorbing member for an automobile door according to claim 2.

5. The tensile strength of the connected portion is 1100 MPa or more.

2. The shock absorbing member for an automobile door according to claim 1.

6. The Vickers hardness of the connected portion is 350 HV or more.

2. The shock absorbing member for an automobile door according to claim 1.

7. The impact absorbing member for an automobile door according to any one of claims 1 to 6, an exterior panel to which the automobile door impact absorbing member is attached; An automobile door having

8. 8. The automobile door according to claim 7, wherein the shock absorbing member for an automobile door is attached to a reinforcing member.

9. The reinforcing member has an open cross section perpendicular to its extending direction, The connecting band portion of the impact absorbing member for an automobile door is attached to the reinforcing member to form a closed cross-sectional structure.

9. The vehicle door according to claim 8.

10. A blank for molding an impact absorbing component for an automobile door, the blank having an impact absorbing portion having a connecting band portion extending in a first direction and at least three connected portions each having one end connected to the connecting band portion and extending in a second direction intersecting the first direction, the connected portions having a closed cross-sectional structure in which the edges of two top surfaces of the connected portions are in contact with, joined to, or opposed to each other with a gap of 3 mm or less, a connecting band portion forming region extending in the first direction and molded on the connecting band portion; At least three connectable portion forming regions, one end of which is connected to the connecting band portion forming region and which extend in the second direction and are formed on the at least three connectable portions; and It is a tailored blank in which a single blank or a plurality of blank steel plates having different thicknesses and strengths or the same thicknesses and strengths are integrally connected. A blank characterized by:

11. The tailored blank, The connecting band portion forming region and the connected portion forming region are integrally connected at a joint portion.

11. The blank of claim 10.

12. the connected portion forming region has an overlapping surface forming region that is overlapped with a part of the connecting band portion forming region, The joining portion is formed on the overlapping surface, so that the connecting band portion forming region and the connected portion forming region are integrally connected at the joining portion.

12. The blank of claim 11.

13. A notch is formed in the vicinity of a portion where the connecting band portion forming region and the connected portion forming region are connected. A blank according to any one of claims 10 to 12.

14. A method for manufacturing an impact absorbing member for an automobile door, comprising: a connecting band portion extending in a first direction; and at least three connected portions, one end of which is connected to the connecting band portion and which extend in a second direction intersecting the first direction, wherein the connected portions have an impact absorbing portion having a closed cross-sectional structure in which the edges of two top surfaces of the connected portions are in contact with, joined to, or opposed to each other with a gap of 3 mm or less; a first step of cold press-forming a blank, the blank having a connecting band portion forming region extending in the first direction and formed into the connecting band portion, and at least three connected portion forming regions each having one end connected to the connecting band portion forming region and extending in the second direction and formed into the at least three connected portions, the blank being a single piece blank or a tailored blank formed by integrally connecting a plurality of blank steel plates having at least one of different thicknesses and strengths, or the same thicknesses and strengths, to obtain an intermediate press-formed product; a second step of press-molding the intermediate press-molded product to obtain an impact absorbing member for an automobile door; Equipped with In the second step, When the blank is a one-piece blank, the intermediate press-formed product is press-formed in a state where it is heated to a temperature of Ac3 point or higher, and when the blank is a tailored blank, the intermediate press-formed product is press-formed in a cold state or in a state where it is heated to a temperature of Ac3 point or higher.

1. A method for manufacturing an impact absorbing member for an automobile door, comprising:

15. the blank is the tailored blank, The connecting band portion forming region and the connected portion forming region are integrally connected at a joint portion. The method for manufacturing an impact absorbing member for an automobile door according to claim 14.

16. the connected portion forming region has an overlapping surface forming region that is overlapped with a part of the connecting band portion forming region, The joining portion is formed on the overlapping surface, so that the connecting band portion forming region and the connected portion forming region are integrally connected at the joining portion. The method for manufacturing an impact absorbing member for an automobile door according to claim 15.

17. In the second step, the intermediate press-formed product is press-formed in a state where the intermediate press-formed product is heated to a temperature of Ac3 point or higher.

17. The method for manufacturing an impact absorbing member for an automobile door according to claim 15 or 16.

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