Joint structure

Abstract

A joint structure according to one embodiment of the present invention comprises: a first metal plate on which is formed a cylindrical first rising section; at least one target material joined to the first metal plate, the target material having formed therein a through-hole into which the first rising section is inserted; and a joint member that is inserted into the first rising section and that joins the overlapped first metal plate and target material. The joint member has a shaft section that is inserted into the interior of the first rising section. A first surface, which is one of two surfaces of the target material and which is opposite the surface that faces the first metal plate, and a leading-edge section of the first rising section are located in different positions in the axial direction of the first rising section.

Description

[Technical Field]

[0001] The present invention relates to a joining structure in which a base material having a burred portion formed thereon and a target material to be joined are joined by a joining member. This application claims priority based on Japanese Patent Application No. 2021-107689, filed on June 29, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] The use of high-strength steel sheets is being promoted to reduce the weight of automobiles and improve crashworthiness. However, spot-welded joints made of high-strength steel sheets face the problem of decreased joint strength as the tensile strength of the base steel sheet increases. For example, when the tensile strength of the base steel sheet exceeds 780 MPa, the cross tensile strength (CTS) decreases. Furthermore, when the tensile strength of the steel sheet exceeds 1500 MPa, not only the cross tensile strength but also the tensile shear strength (TSS) tends to decrease.

[0003] Cross tensile strength refers to the strength of a joint against peel stress. Peel stress refers to the stress applied to a joint by pulling two or more metal plates that make up the joint structure perpendicular to the plate surfaces and away from each other. Tensile shear strength refers to the strength of a joint against shear stress. Shear stress refers to the stress applied to a joint by pulling two metal plates that make up the joint structure parallel to the plate surfaces and away from each other. Cross tensile strength (CTS) is measured in accordance with JIS Z 3137:1999, and tensile shear strength (TSS) is measured in accordance with JIS Z 3136:1999.

[0004] The decrease in joint strength occurs due to embrittlement of the nugget formed in high-strength steel sheets with a high carbon content. High-strength steel sheets have their toughness ensured by optimizing their metallurgical structure through heat treatment under various conditions. However, when high-strength steel sheets are spot welded, the metallurgical structure changes in the nugget and the surrounding heat-affected zone, resulting in embrittlement of the joint.

[0005] If the strength of a spot-welded joint is reduced, there is a risk of the weld breaking when the component is deformed due to a collision under extremely severe conditions. Therefore, even if the strength of the steel plate is improved, the load-bearing capacity of the component as a whole may be insufficient. Therefore, there is a need for a joining method that improves the strength of joints made of high-strength steel plates.

[0006] In addition to welding, plate-like members can also be joined by mechanical joining using joining members such as rivets. For example, the following techniques have been disclosed regarding joined structures obtained by mechanical joining.

[0007] Patent Document 1 discloses a thin plate joining structure in which a joining shaft is inserted into joining holes formed in the thin plate and the object to be joined, and the thin plate and the object to be joined are fastened together by the joining shaft and a fixing part that is either integral with or separate from the joining shaft, and the thin plate is joined to the object to be joined, characterized in that a cylindrical flange is continuously protruded from around the joining hole formed in the thin plate, and a bag-shaped part that fits onto the outer periphery of the cylindrical flange is provided on the joining shaft or the fixing part. Furthermore, as a conventional example of a joining structure in which a base material having a burred portion formed thereon and a target material to be joined are joined with a joining member, Patent Document 2 discloses a joining structure for plate materials in a vehicle in which a thin plate and a thick plate stacked on top of each other are joined by a fastening means through a through hole provided in each of the plate and the plate, characterized in that the through hole in the thin plate is formed in a burred shape having a cylindrical portion. In this joining structure, an insertion hole through which the burred portion of the base material is inserted is formed in the target material, and in a state in which the target material and the base material are stacked by inserting the burred portion into the insertion hole, the target material is joined to the base material by a joining member having a shaft portion formed with an outer circumferential surface that contacts the inner circumferential surface of the burred portion. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2001-12421 [Patent Document 2] Japanese Patent Application Publication No. 2003-260964 Summary of the Invention [Problem to be solved by the invention]

[0009] The present inventors have focused on riveting as one means of improving the cross tensile strength of joints. Riveting is a joining method in which a through hole is formed in metal plates, a rivet with a head and a shank is inserted into the through hole, the tip of the rivet shank is plastically deformed, and the metal plates are crimped together by the rivet head and plastically deformed portion. The present inventors have discovered that the cross tensile strength of joints (riveted joints) obtained by riveting high-strength steel plates is significantly higher than that of spot-welded joints. Riveting, which mechanically joins steel plates, does not cause embrittlement of the joint, and is therefore thought to be able to maintain a high CTS for joints made of high-strength steel plates. However, the present inventors' experiments have also revealed that riveted joints do not improve tensile shear strength (TSS).

[0010] The technology of Patent Document 1 does not consider means for improving TSS in riveting. While Patent Document 1 aims to provide a thin plate joining structure that can join thin plate members with high strength and rigidity, it does not particularly consider the direction of stress applied to the joining shaft, and therefore does not focus on improving TSS. Furthermore, Patent Document 1 does not disclose any configuration for improving TSS.

[0011] According to the joining structure of Patent Document 2, the outer surface of the shank of the joining member contacts the inner surface of the burred portion. Therefore, when an external load is applied that separates the target material and the base material constituting the plate assembly, the load acting on the joining member in a direction perpendicular to the axial direction, i.e., the load that shears the shank, is transmitted from the inner surface of the burred portion. This allows the load to be distributed over the axial length of the contact area between the inner surface and the shank, reducing stress concentration in the shank compared to when a joining member is simply used to join a base material and a target material without a burred portion. This can be expected to improve the TSS and CTS of the joining structure. However, if the joining structure is such that the first surface, which is the surface opposite the opposing surface facing the base material, and the tip of the burring portion are at the same position in the axial direction of the burring portion, there is a problem that the joining structure cannot be properly configured depending on the combination of the plate thickness of the target material and the plate thickness of the base material, or that it is disadvantageous against loads in the direction of shearing the shaft portion. For example, if the target material is thick, the axial length of the burring portion must be increased, in other words, a tall burring portion must be formed. However, depending on the material properties (e.g., hole expandability) and the thickness of the substrate, cracks may occur during the burring process, making it impossible to form a burring portion with a height corresponding to the first surface of the target material. Furthermore, for example, if the target material is thin, the height of the burring portion must be formed accordingly low, which limits the axial length of the inner peripheral surface of the burring portion that contacts the shank. As a result, the area of the inner peripheral surface that contacts the shank is limited, which creates a problem of being disadvantageous against loads in the direction of shearing the shank. In this way, a joining structure in which the first surface, which is the surface opposite the opposing surface facing the base material, and the tip of the burring portion are at the same position in the axial direction of the burring portion has the problem that, when the plate thickness of the target material to be joined to the base material is also taken into consideration, it cannot necessarily be said to be a desirable joining structure in terms of joining strength.

[0012] In view of the above circumstances, a joining structure is desired that can ensure a preferable joining strength depending on the plate thickness of the material to be joined to the base material. [Means for solving the problem]

[0013] The gist of the present invention is as follows.

[0014] (1) A joining structure according to one aspect of the present invention includes a first metal plate having a cylindrical first raised portion formed thereon, one or more target materials having a through hole through which the first raised portion is inserted and joined to the first metal plate, and a joining member that is inserted into the first raised portion and joins the overlapping first metal plate and the target materials, wherein the joining member has an axial portion inserted inside the first raised portion, and a first surface, which is one of both surfaces of the target material opposite to the surface facing the first metal plate, and a tip of the first raised portion are located at different positions in the axial direction of the first raised portion. (2) In the joining structure described in (1) above, preferably, the joining member has a pair of protrusions provided at both ends of the shaft portion and protruding radially outward from the shaft portion, thereby joining the first metal plate and the target material. (3) In the joining structure described in (1) or (2) above, preferably, one or more of the target materials is a second metal plate having a second raised portion, the second raised portion being a cylindrical region rising from the edge of the second through hole, which is the through hole provided in the second metal plate, and the first raised portion being inserted between the second raised portion and the shaft portion. (4) In the joining structure described in (3) above, preferably, the second rising portion is obtained by bending the second metal plate, the first rising portion and the second rising portion rise in the same direction, and in a direction perpendicular to the first metal plate, the tip of the first rising portion is farther from the first metal plate than the tip of the second rising portion. (5) In the joining structure described in (1) or (2) above, preferably, the rising portion is provided only on the first metal plate. (6) In the joining structure described in any one of (2) to (5) above, preferably, the internal space of the first rising portion has a curved shape that narrows from the base to the top of the first rising portion, and the protrusion of the joining member arranged on the base side of the first rising portion has a curved shape that follows the inner surface of the first rising portion. (7) In the joint structure according to any one of (2) to (6) above, preferably, the first rising portion is structure The protruding portion of the joining member protrudes from the surface of the board assembly constituting the board assembly, has a shape that is expanded to fit along the surface of the board assembly, and contacts the first rising portion, and fixes the board assembly via the first rising portion. (8) In the joint structure according to any one of (1) to (7) above, the first rising portion preferably protrudes from the first surface of the target material. (9) In the joining structure described in (8) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material covers the first rising portion protruding from the first surface of the target material. (10) In the joining structure described in (9) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material. (11) In the joint structure according to any one of (3) to (7) above, the second rising portion preferably projects from the first surface of the target material. (12) In the joining structure described in (11) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material covers the second rising portion protruding from the first surface of the target material. (13) In the joining structure described in (12) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material. (14) In the joint structure according to any one of (3) to (7) above, preferably, both the first rising portion and the second rising portion protrude from the first surface of the target material. (15) In the joining structure described in (14) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material covers both the first rising portion and the second rising portion protruding from the first surface of the target material. (16) In the joining structure described in (15) above, preferably, the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material. (17) The joint structure according to any one of (1) to (16) above preferably further comprises an adhesive applied to at least one of the mating surfaces of the plurality of metal plates. [Effects of the Invention]

[0015] According to the joining structure of the present invention, it is possible to ensure a preferable joining strength depending on the plate thickness of the material to be joined to the base material. [Brief explanation of the drawings]

[0016] [Figure 1A] FIG. 10 is a cross-sectional view of a joining structure according to one embodiment of the present invention, in which the tip of a first rising portion is located inside the surface of the plate assembly. [Figure 1B] 1 is a cross-sectional view of a joint structure according to one embodiment of the present invention, in which the tip of a first rising portion protrudes outward from the surface of a plate assembly. [Figure 2A] FIG. 1 is a schematic diagram of shear stress in a conventional joint structure. [Figure 2B] 5A and 5B are schematic diagrams of shear stress in the joint structure according to the present embodiment. [Figure 3] FIG. 10 is a cross-sectional view of a joint structure having a second rising portion. [Figure 4A] This is an example of a joint structure with three metal plates. [Figure 4B] This is an example of a joint structure with three metal plates. [Figure 4C] This is an example of a joint structure with three metal plates. [Figure 5A] This is an example of a joining structure in which the top of the first rising portion protrudes from the surface of the plate assembly. [Figure 5B] This is an example of a joining structure in which the top of the first rising portion protrudes from the surface of the plate assembly. [Figure 5C] This is an example of a joining structure in which the top of the first rising portion protrudes from the surface of the plate assembly. [Figure 6A] This is an example of a joining structure in which the tops of the first rising portion and the second rising portion protrude from the surface of the plate assembly. [Figure 6B] This is an example of a joining structure in which the tops of the first rising portion and the second rising portion protrude from the surface of the plate assembly. [Figure 6C] This is an example of a joining structure in which the tops of the first rising portion and the second rising portion protrude from the surface of the plate assembly. [Figure 7] This is an example of a joining structure in which the internal space of the base of the first rising portion and the first protruding portion of the joining member have curved shapes. [Figure 8]This is the analysis result of the resistance force of various joint structures to in-plane tensile stress. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1A and 1B, a joining structure 1 according to a first configuration of the present application includes a first metal plate 111 having a cylindrical first rising portion 1112 formed therein, one or more target materials (a second metal plate 112 or a flat metal plate 113) having a through-hole 1131 through which the first rising portion 1112 is inserted and joined to the first metal plate 111, and a joining member 12 inserted through the first rising portion 1112 to join the overlapping first metal plate 111 and the target materials, wherein the joining member 12 has a shaft portion 123 inserted inside the first rising portion 1112, and a first surface X, which is one of both surfaces of the target material opposite to the surface facing the first metal plate 111, and a tip end of the first rising portion 1112 are positioned at different positions in the axial direction of the first rising portion 1112.

[0018] Hereinafter, the first metal plate 111 may be referred to as a "substrate." The first metal plate 111 is provided with a cylindrical first rising portion 1112. The first rising portion 1112 is, for example, a burring portion.

[0019] The target material is a metal plate having a through-hole 1131 through which the first rising portion 1112 is inserted and joined to the base material, i.e., the first metal plate 111. The number of target materials may be one, or two or more. As will be described later, the target material may or may not have a rising portion. In the joining structure 1 according to this embodiment, the target material having a rising portion is referred to as a "second metal plate 112," and the target material not having a rising portion that is joined to the first metal plate 111 is referred to as a "flat metal plate 113." In other words, the target material is a second metal plate 112 through which the first rising portion 1112 is inserted and on which a cylindrical rising portion is formed; and A flat metal plate 113 through which the first rising portion 1112 is inserted and which does not have a cylindrical rising portion formed thereon. 1A and 1B, the target material through which the first rising portion 1112 is inserted corresponds to the flat metal plate 113 because it does not have a rising portion. The joining member 12 has a shaft portion 123 inserted inside the first rising portion 1112. Since the first rising portion 1112 is inserted into the through hole of the target material, it goes without saying that the shaft portion 123 inserted inside the first rising portion 1112 is also inserted into the through hole of the target material. The axis of the shaft portion 123 may coincide with the axis of the burring portion.

[0020] Of both surfaces of the target material, the first surface X, which is the surface opposite to the surface facing the first metal plate 111, and the tip of the first rising portion 1112 are located at different positions in the axial direction of the first rising portion 1112. Here, "both surfaces of the target material" refers to both surfaces of the target material when there is one target material, and refers to the two surfaces of the group of stacked target materials into which the first raised portion 1112 is inserted when there are two or more target materials. In other words, "both surfaces of the target material" is a concept that does not include the mating surfaces of two target materials. Of the two surfaces of the target material, the surface that does not contact the first metal plate 111 is the first surface X. As illustrated in FIG. 4C , when the first raised portion 1112 is provided on both surfaces of the first metal plate 111 and the target material is also provided on both surfaces of the first metal plate 111, the first surface X also exists on both surfaces of the first metal plate 111. "The first surface X and the tip of the first raised portion 1112 are at different positions in the axial direction" means, in other words, that the first surface X and the tip of the first raised portion 1112 are not on the same plane perpendicular to the axial direction. In FIG. 1A, the tip of the first raised portion 1112 is inside the through hole of the target material. In FIG. 1B, the tip of the first raised portion 1112 protrudes outside the through hole of the target material. In both the configurations shown in FIG. 1A and FIG. 1B, the first surface X and the tip of the first raised portion 1112 are at different positions in the axial direction.

[0021] The effects of the joint structure 1 according to the first configuration of the present invention will be described below. According to the first configuration of the present application, the first surface X, which is the surface opposite the surface facing the substrate among both surfaces of the target material, and the tip of the burring portion are different in the axial direction of the burring portion. Therefore, even if the target material is thick, it is not necessary to adjust the height of the burring portion to the thickness of the target material. It is sufficient to form a burring portion with a height appropriate for the material properties (e.g., hole expandability) and the thickness of the substrate. In this case, even if the tip of the burring portion is positioned closer to the substrate in the axial direction than the first surface X without aligning the position of the tip of the burring portion and the position of the first surface X of the target material so that they are the same in the axial direction, a burring portion of sufficient height can be formed if the target material is thick. Therefore, when the target material is thick, by positioning the tip of the burring portion closer to the substrate in the axial direction than the first surface X, it is possible to ensure joining strength while avoiding cracking of the burring portion. Furthermore, according to the first configuration of the present application, the first surface X, which is the surface opposite the surface facing the base material among both surfaces of the target material, and the tip of the burring portion are different in the axial direction of the burring portion, so even if the target material has a thin plate thickness, there is no need to adjust the height of the burring portion to the plate thickness of the target material, and a tall burring portion can be formed regardless of the plate thickness of the target material, and a burring portion with a height that protrudes further toward the tip than the first surface X of the target material can be formed. As a result, when a load is applied from the outside that separates the target material and the base material that constitute the plate assembly 11 from each other, the area of the inner circumferential surface of the burring portion that contacts the shank 123 can be increased in the axial direction, and the load in the direction that shears the shank 123 can be appropriately distributed, ensuring the strength of the joint structure. Thus, according to the first configuration of the present application, which is a joining structure in which the first surface X, which is the surface opposite to the opposing surface facing the base material among both surfaces of the target material, and the tip end of the burring portion are located at different positions in the axial direction of the burring portion, it is possible to ensure a preferable joining strength according to the plate thickness of the target material to be joined to the base material.

[0022] Specific examples and more preferred embodiments of the joint structure 1 according to this embodiment will be described in detail below. The joining structure 1 according to this embodiment includes a plate assembly 11 in which multiple metal plates are stacked together, and a joining member 12 that joins the plate assembly 11. Each of the metal plates included in the plate assembly 11 has a through-hole that is aligned. The multiple metal plates included in the plate assembly 11 are the first metal plate 111 and the target material described above. The through-hole provided in the first metal plate 111 is inside the cylindrical first rising portion 1112 described above. The joining member 12 has a shaft portion 123. The joining member 12 may have a pair of protrusions provided on both ends of the shaft portion 123 and protruding radially outward from the shaft portion 123. In this embodiment, for convenience, the protrusion on the base side of a first rising portion 1112 described below may be referred to as a first protrusion 121, and the protrusion on the top side of the first rising portion 1112 may be referred to as a second protrusion 122, but the two are equivalent. 1A and 1B are approximate boundaries between the shaft portion 123 and the first and second protrusions 121 and 122. In the joining member 12, the first and second protrusions 121 and 122 are portions that protrude radially from the end of the shaft portion 123 and occupy a ring-shaped region. The shaft portion 123 is inserted into the through-hole. The joining member 12 uses the pair of protrusions to join the multiple metal plates of the plate assembly 11. As will be described later, the joining member 12 is, for example, a rivet or a combination of a bolt and a nut. In the joint structure 1 according to this embodiment, one of the multiple metal plates has a first rising portion 1112. Hereinafter, the metal plate having the first rising portion 1112 will be referred to as a first metal plate 111. The through hole provided in the first metal plate 111 will be referred to as a first through hole 1111. A metal plate without a rising portion will be referred to as a flat metal plate 113. Hereinafter, the joint structure 1 will be described using as an example a plate assembly 11 in which the first metal plate 111 and the flat metal plate 113 are combined.

[0023] The first rising portion 1112 is a cylindrical region formed on the edge of the first through-hole 1111. The first rising portion 1112 is, for example, a burring portion provided on the first metal plate 111. The first rising portion 1112 has a shape that rises from the edge of the first through-hole 1111. The first rising portion 1112 is inserted between the edge of the through-hole of a metal plate adjacent to the first metal plate 111 and the shaft portion 123 of the joining member 12. In other words, the first rising portion 1112 is inserted into the through-hole of a metal plate overlapping the first metal plate 111, and the shaft portion 123 is inserted into the first rising portion 1112. A and Figure 1B In the example shown in FIG. 1, a first rising portion 1112 is inserted into a through-hole 1131 of a flat metal plate 113. However, as will be described later, the metal plate adjacent to the first metal plate 111 may be a second metal plate 112 having a second rising portion 1122.

[0024] When two metal plates included in plate assembly 11 of joint structure 1 are pulled parallel to the plate surfaces and in directions away from each other, first rising portion 1112 has the effect of preventing breakage of shaft portion 123. The reason for this will be explained below with reference to Figures 2A and 2B. The arrows in FIG. 2A indicate the shear stress applied to the shank 123 in a conventional joint structure without a raised portion when the lower metal plate is pulled to the right and the upper metal plate is pulled to the left. The arrows in FIG. 2B indicate the shear stress applied to the shank 123 in the joint structure 1 according to this embodiment when the lower metal plate, i.e., the first metal plate 111, is pulled to the right and the upper metal plate, i.e., the flat metal plate 113, is pulled to the left. As shown in FIG. 2A, in the conventional joint structure, the contact area between the metal plate, which applies shear stress to the shank 123, and the shank 123 is small. Therefore, the shear stress applied to the shank 123 per contact area is large. On the other hand, as shown in FIG. 2B, in the joint structure 1 provided with the first raised portion 1112, the contact area between the first raised portion 1112, which applies shear stress to the shank 123, and the shank 123 is large. This reduces the shear stress per contact area applied to the stem 123, thereby preventing breakage of the stem 123. For the above reasons, the joint structure 1 having the first rising portion 1112 has a significantly higher TSS than conventional joint structures. The first raised portion 1112 also serves to facilitate the alignment of the through holes. When multiple metal plates with through holes formed in advance are stacked together and then the joining member 12 is inserted through the through holes, the alignment of the multiple through holes is required. Here, the alignment of the through holes can be achieved by inserting the first raised portion 1112 into the through holes of the metal plate stacked on the first metal plate 111.

[0025] As described above, in the joining structure 1, the first surface X, which is the surface opposite to the surface facing the first metal plate 111, of both surfaces of the target material, and the tip of the first rising portion 1112 are located at different positions in the axial direction of the first rising portion 1112. This eliminates the need to adjust the plate thickness of the target material and the length of the first rising portion 1112. A rising portion of a height suitable for the material properties and various configurations of the first metal plate 111, such as the plate thickness, can be freely formed on the first metal plate 111.

[0026] In the joint structure 1 according to this embodiment, the rising portion may be provided only on the first metal plate 111. In other words, the plate assembly 11 of the joint structure 1 may be composed of the first metal plate 111 having the first rising portion 1112 and one or more flat metal plates 113. By limiting the number of rising portions, the cost of processing the metal plates can be reduced. On the other hand, as shown in FIG. 3 , two or more rising portions may be formed in the joint structure 1. That is, one or more of the metal plates excluding the first metal plate 111 may be a second metal plate 112 having a second rising portion 1122. Hereinafter, a metal plate having a second rising portion 1122 will be referred to as the second metal plate 112. Furthermore, the through hole provided in the second metal plate 112 will be referred to as the second through hole 1121. The second rising portion 1122 is a cylindrical region formed at the edge of the second through hole 1121. The second rising portion 1122 rises from the edge of the second through hole 1121. Furthermore, the second rising portion 1122 surrounds the first rising portion 1112. In other words, the first rising portion 1112 is inserted between the second rising portion 1122 and the shaft portion 123 of the joint member 12. 3, the tip of the second rising portion 1122 and the tip of the first rising portion 1112 are at the same position in the axial direction of the first rising portion 1112. Such a configuration is permitted in the joining structure 1 according to this embodiment. The second rising portion 1122 is considered not to be included in the surface of the second metal plate 112.

[0027] For reference, in this embodiment, the first metal plate 111, the second metal plate 112, and the flat metal plate 113 are distinguished from one another by defining the names of the components as follows: First metal plate 111: A metal plate having a raised portion, and no other raised portion inserted inside the raised portion. Second metal plate 112: A metal plate having a raised portion, and another raised portion inserted inside the raised portion. Flat metal plate 113: a metal plate without a raised portion

[0028] In addition, two or more second metal plates 112 may be included in the joint structure 1. Also, if the plate assembly 11 includes four or more metal plates, two or more first metal plates 111 may be included in the joint structure 1. For example, in FIG. A and Figure 1B When two plate pairs 11 included in the joint structure 1 shown in FIG. 1 are stacked and joined together, a joint structure 1 including two first metal plates 111 can be manufactured.

[0029] Furthermore, the term "metal plate" is used as a general concept that refers to the first metal plate 111, the second metal plate 112, and the flat metal plate 113. Furthermore, the term "target material" is used as a general concept that refers to the second metal plate 112 and the flat metal plate 113. The term "through hole" is used as a general concept that refers to the first through hole 1111, the second through hole 1121, and the through hole 1131 of the flat metal plate, and the term "raised portion" is used as a general concept that refers to the first raised portion 1112 and the second raised portion 1122.

[0030] One advantage of providing the second rising portion 1122 is that it is possible to provide a rising portion that is larger than the total plate thickness of the plate assembly 11. This makes it possible to prevent breakage of the shaft portion 123. Another advantage of providing the second rising portion 1122 is that the second rising portion 1122 can alleviate the reaction force per contact area applied from the first rising portion 1112. This makes it possible to prevent breakage of the second rising portion 1122.

[0031] In the configurations illustrated in FIGS. 1A, 1B, and 3, the plate assembly 11 is composed of two metal plates. On the other hand, as shown in FIGS. 4A to 4C, the plate assembly 11 may include three or more metal plates. FIG. 4A shows a joint structure 1 composed of a first metal plate 111 and two flat metal plates 113 stacked on top of it. FIG. 4B shows a joint structure 1 composed of a first metal plate 111, a second metal plate 112 stacked on top of it, and a flat metal plate 113 stacked on top of that. In either case, the rising portion can exhibit a TSS-improving effect. Furthermore, FIG. 4C shows a joint structure 1 composed of a first metal plate 111 and two flat metal plates 113 stacked on either side of it. FIG. 1 A and Figure 1B In the above example, the rising portion is provided to rise from only one side of the metal plate. However, as illustrated in FIG. 4C , the first rising portion 1112 may be provided to rise from both sides of the metal plate. Even in this case, the first rising portion 1112 can exhibit the effect of improving the TSS. Although not illustrated in the figure, it is of course possible to place a flat metal plate 113 between the first metal plate 111 and the second metal plate 112, or to place the first metal plate 111 between the second metal plate 112 and the flat metal plate 113. The number of metal plates may be four or more. In the joining structure 1 according to this embodiment, the number of metal plates included in the plate set 11 is not limited, and various combinations of the first metal plate 111, the second metal plate 112, and the flat metal plate 113 can be used depending on the number of plates.

[0032] 1A and other drawings, the first rising portion 1112 is depicted as rising perpendicularly to the first metal plate 111. However, the first rising portion 1112 may form an angle of, for example, 45° or more and less than 90° with respect to the first metal plate 111. The second rising portion 1122 may also rise perpendicularly to the second metal plate 112, or may form an angle of, for example, 45° or more and less than 90° with respect to the second metal plate 112.

[0033] As long as the positional relationship between the first surface X of the target material and the tip of the first raised portion 1112 satisfies the above-mentioned requirements, the height H1 of the first raised portion 1112 and the height H2 of the second raised portion 1122 are not particularly limited. However, a preferred example will be described below. Here, the height H1 of the first raised portion 1112 is the distance, measured along a direction perpendicular to the first metal plate 111, between the surface on which the first raised portion 1112 is provided and the apex of the first raised portion 1112. The height H1 is shown in FIG. 5A and other figures. Similarly, the height H2 of the second raised portion 1122 is the distance, measured along a direction perpendicular to the second metal plate 112, between the surface on which the second raised portion 1122 is provided and the apex of the second raised portion 1122. 5A and other figures, the top of the rising portion may be deformed. In this case, the height of the contact portion between the first rising portion 1112 and the joining member 12 may be regarded as the height H1 of the first rising portion 1112. The height of the contact portion between the second rising portion 1122 and the first rising portion 1112 may be regarded as the height H2 of the second rising portion 1122.

[0034] The lower limit values of H1 and H2 are not particularly limited as long as they are greater than 0 mm. This is because even if the rising portion rises slightly from the plate surface of the metal plate, the rising portion has the effect of mitigating the shear stress per unit area applied to the shaft portion 123 or the first rising portion 1112, thereby improving the TSS. On the other hand, it is believed that the larger H1 and H2 are, the more the TSS is improved.

[0035] Hereinafter, the height H1 of the first rising portion 1112 will be described first. With regard to H1, the upper and lower limits of the height may be determined based on the thickness of the first metal plate 111. For example, H1 may be set to 20% or more, 30% or more, 50% or more, 80% or more, or 100% or more of the thickness of the first metal plate 111. On the other hand, H1 may be set to 200% or less, 180% or less, 150% or less, or 120% or less of the thickness of the first metal plate 111.

[0036] Furthermore, the upper and lower limits of the height H1 may be determined based on the thickness of the second metal plate 112. Specifically, H1 may be defined as 20% or more, 30% or more, 50% or more, 80% or more, more than 100%, or 110% or more of the thickness of the second metal plate 112. On the other hand, H1 may be defined as 200% or less, 180% or less, 150% or less, 120% or less, less than 100%, or 90% or less of the thickness of the second metal plate 112. Furthermore, the upper and lower limits of the height H1 may be determined based on the thickness of the flat metal plate 113. Specifically, H1 may be defined as 20% or more, 30% or more, 50% or more, 80% or more, more than 100%, or 110% or more of the thickness of the flat metal plate 113. On the other hand, H1 may be defined as 200% or less, 180% or less, 150% or less, 120% or less, less than 100%, or 90% or less of the thickness of the flat metal plate 113. Additionally, the upper and lower limits of the height H1 may be determined based on the thickness of the target material. When there are two or more target materials, the thickness of the target material refers to the total thickness of the multiple target materials. H1 may be defined as 20% or more, 30% or more, 50% or more, 80% or more, more than 100%, or 110% or more of the thickness of the target material. On the other hand, H1 may be defined as 200% or less, 180% or less, 150% or less, 120% or less, less than 100%, or 90% or less of the thickness of the target material.

[0037] When H1 is large, as shown in FIG. 1B, the first raised portion 1112 protrudes from the surface of the plate assembly 11, i.e., the first surface X of the target material. In this case, the second protrusion 122 of the joining member 12 does not need to contact the metal plate arranged on the surface of the plate assembly 11. In this case, the metal plate can move in the plate thickness direction of the plate assembly 11. However, even if the metal plate is not tightly fixed, the first raised portion 1112 can effectively increase the TSS of the joining structure 1. Furthermore, when the first raised portion 1112 protrudes from the first surface X of the target material, a spacer may be fitted between the first surface X of the target material and the second protrusion 122 of the joining member 12 to suppress rattle of the metal plate.

[0038] As shown in Fig. 5A, the first raised portion 1112 may protrude from the surface of the plate set 11 and may have a shape that is expanded to fit along the surface of the plate set 11. In Fig. 5A, the second raised portion 122 of the joining member 12 does not contact the flat metal plate 113. However, the top of the first raised portion 1112 has a shape that extends along the surface of the plate set 11 toward the outside of the through hole. Therefore, the second raised portion 122 of the joining member 12 can tightly fix the plate set 11 via the first raised portion 1112.

[0039] As shown in FIG. 5B , the first raised portion 1112 may protrude from the first surface of the target material (i.e., the surface of the board set 11). In this case, the protruding portion of the joining member arranged on the side of the first surface of the target material may cover the first raised portion protruding from the first surface of the target material. In other words, the second protruding portion 122, which is a protruding portion that contacts the top of the first raised portion 1112, may cover the first raised portion 1112. Furthermore, the protruding portion of the joining member arranged on the side of the first surface of the target material (i.e., the second protruding portion 122 of the joining member 12) may contact the first surface of the target material (i.e., the surface of the board set 11). This allows the second protruding portion 122 to tightly fix the board set 11. Furthermore, by preventing deformation of the first rising portion 1112, the second protrusion 122 further suppresses the joining member 12 from falling out of the through-hole of the joining structure 1, thereby further improving the TSS and CTS of the joining structure 1. For example, a joining structure 1 having such a configuration can be manufactured by using a rivet as the joining member 12, arranging the tip of the rivet on the top side of the first rising portion 1112, and plastically deforming this tip. Alternatively, a joining structure 1 having such a structure can be manufactured by using a bolt and nut as the joining member 12, and providing a recess in the countersunk portion of the bolt or the nut that can accommodate the top of the first rising portion 1112.

[0040] 5A and 5B may be combined. That is, as shown in Fig. 5C, the first rising portion 1112 may protrude from the surface of the plate set 11 and have a shape that is expanded to fit along the surface of the plate set 11, and the second protruding portion 122, which is a protruding portion that contacts the top of the first rising portion 1112, may cover the first rising portion 1112 and contact the surface of the plate set 11.

[0041] Next, the height H2 of the second rising portion 1122 will be described. As described above, the lower limit of H2 is greater than 0 mm. Furthermore, for example, H2 may be defined as 5% or more, 10% or more, 20% or more, 50% or more, or 80% or more of the height H1 of the first rising portion 1112. On the other hand, H2 may be defined as 120% or less, 100% or less, 80% or less, or 50% or less of H1.

[0042] Like the first rising portion 1112, the second rising portion 1122 may also protrude from the surface of the plate set 11. As shown in Fig. 3, if no other metal plate is disposed on the surface of the second metal plate 112, the second rising portion 1122 will inevitably protrude from the surface of the plate set 11. On the other hand, as shown in Fig. 4B, if a flat metal plate 113 is disposed on the surface of the second metal plate 112, the top of the second rising portion 1122 may not protrude from the plate set 11.

[0043] 6A , the second rising portion 1122 may protrude from the surface of the plate set 11 and may have a shape that is expanded to fit along the surface of the plate set 11. When a flat metal plate 113 is disposed on the surface of the second metal plate 112, the expanded second rising portion 1122 and the second metal plate 112 may sandwich the flat metal plate 113. Furthermore, the first rising portion 1112 may be expanded to fit along the surface of the second rising portion 1122.

[0044] Similar to the first rising portion 1112, the second rising portion 1122 may protrude from the first surface of the target material (i.e., the surface of the board set 11). In this case, the protruding portion of the joining member arranged on the side of the first surface of the target material may cover the second rising portion protruding from the first surface of the target material. In other words, the second protruding portion 122, which is a protruding portion that contacts the top of the second rising portion 1122, may cover the second rising portion 1122. Furthermore, the protruding portion of the joining member arranged on the side of the first surface of the target material may contact the first surface of the target material (i.e., the surface of the board set 11). This allows the second protruding portion 122 of the joining member 12 to tightly fix the board set 11. 6B, both the first rising portion 1112 and the second rising portion 1122 may protrude from the first surface of the target material (i.e., the surface of the board set 11). In this case, the protruding portion of the joining member arranged on the side of the first surface of the target material may cover both the first rising portion and the second rising portion protruding from the first surface of the target material. In other words, the second protruding portion 122 of the joining member 12 may cover both the first rising portion 1112 and the second rising portion 1122. Furthermore, the protruding portion of the joining member arranged on the side of the first surface of the target material may be in contact with the first surface of the target material (i.e., the surface of the board set 11).

[0045] 6A and 6B may be combined. That is, as shown in FIG. 6C, one or both of the first rising portion 1112 and the second rising portion 1122 may protrude from the surface of the plate set 11 (i.e., the first surface X of the target material). Furthermore, one or both of the first rising portion 1112 and the second rising portion 1122 may have a shape that is expanded so as to fit along the surface of the plate set 11 or the surface of the second rising portion 1122. In addition, the second protrusion 122 of the joining member 12 may cover one or both of the first rising portion 1112 and the second rising portion 1122 that protrude from the surface of the plate set 11 (i.e., the first surface X of the target material) and may be in contact with the surface of the plate set 11 (i.e., the first surface X of the target material).

[0046] Next, the thickness of the rising portion will be described. A thicker rising portion is preferable because it increases the resistance of the rising portion to shear stress. Therefore, the thickness of the first rising portion 1112 may be 50% or more, 60% or more, 80% or more, 100% or more, or 110% or more of the thickness of the first metal plate 111. Similarly, the thickness of the second rising portion 1122 may be 50% or more, 60% or more, 80% or more, 100% or more, or 110% or more of the thickness of the second metal plate 112. For example, a rising portion of any thickness can be formed by welding a metal tube to the edge of the through-hole of the metal plate. Note that the thickness of the first rising portion 1112 is a value measured based on the surface on which the first rising portion 1112 is provided, out of the two surfaces of the first metal plate. Specifically, in a cross section including the axis of the joining member 12, a straight line is drawn along the surface of the two surfaces of the first metal plate on which the first rising portion 1112 is provided, and the length of the portion of this line that overlaps with the first rising portion 1112 is regarded as the thickness of the first rising portion 1112. Similarly, the thickness of the second rising portion 1122 is a value measured based on the surface of the two surfaces of the second metal plate on which the second rising portion 1122 is provided. Specifically, in a cross section including the axis of the joining member 12, a straight line is drawn along the surface of the two surfaces of the second metal plate on which the second rising portion 1122 is provided, and the length of the portion of this line that overlaps with the second rising portion 1122 is regarded as the thickness of the second rising portion 1122.

[0047] The method for manufacturing the raised portion is not particularly limited. For example, the raised portion can be formed by welding a metal tube having an inner diameter approximately the same as that of the through hole to the metal plate. When the cross section of the joint structure 1 obtained by welding is appropriately prepared and then observed, the presence of a weld joining the raised portion and the metal plate can be confirmed. The raised portion may also be formed by burring. Burring is a mechanical process in which a hole is drilled in the metal plate and the material of the drilled portion is stretched perpendicular to the surface of the metal plate to form a flange on the edge of the through hole. When the cross section of the joint structure 1 obtained by burring is observed, it can be seen that the raised portion is obtained by bending, and that the raised portion and the metal plate are integrally formed.

[0048] When second rising portion 1122 is obtained by bending (burring) second metal plate 112, that is, when second rising portion 1122 is formed continuously from second metal plate 112, and when first rising portion 1112 and second rising portion 1122 rise in the same direction, it is preferable that the apex of first rising portion 1112 (i.e., the tip of first rising portion 1112) is farther from first metal plate 111 than the apex of second rising portion 1122 (i.e., the tip of second rising portion 1122) in the direction perpendicular to the surface of first metal plate 111. For example, it is preferable that the apex of first rising portion 1112 and the apex of second rising portion 1122 have the positional relationship shown in FIG. 6B.

[0049] When forming the raised portion by burring, thinning of the metal plate may occur. By applying the above-described shape to the joint structure 1, thinning of the second metal plate 112 can be prevented. This makes it possible to prevent the thinned portion from breaking when stress is applied to the joint structure 1 in the peeling direction. Therefore, the CTS of the joint structure 1 can be further improved.

[0050] The inner diameter of the rising part is shown in Figure 1. A and Figure 1BAs shown in Fig. 7, the width may be constant in the direction perpendicular to the metal plate. On the other hand, as shown in Fig. 7, for example, the internal space of the first raised portion 1112 and / or the second raised portion 1122 may have a curved shape that tapers from the base to the top. The raised portions formed by burring often have such a curved shape.

[0051] When the internal space of the first rising portion has a curved shape that narrows from its base to its apex, as shown in FIG. 7, it is preferable that the protrusion (i.e., the first protrusion 121) arranged on the base side of the first rising portion has a curved shape that follows the inner surface of the first rising portion. In other words, it is preferable that the protrusion fills the interior of the first rising portion. In this case, the protrusion amount of the first protrusion 121 becomes smaller as it moves toward the center of the joint structure 1 in the axial direction. That is, the protrusion amount of the first protrusion 121 continuously decreases in the axial direction. This further increases the contact area between the shaft portion 123 and the first rising portion 1112, further disperses shear stress, and further improves the TSS of the joint structure 1.

[0052] The joint structure 1 according to this embodiment can be further applied to various configurations.

[0053] The material of the metal plates constituting the plate set 11 is not particularly limited. For example, using steel plates, particularly high-strength steel plates (e.g., steel plates with a tensile strength TS of approximately 590 MPa or more), as the metal plates constituting the plate set 11 is preferable because it improves the strength of the joint structure 1. Furthermore, when manufacturing the joint structure 1 according to this embodiment, embrittlement, which would result in a decrease in CTS and TSS, is prevented from occurring in the high-strength steel plates. When the tensile strength of the high-strength steel plates is 980 MPa or more, the superiority of the riveting according to this embodiment in terms of CTS becomes even more pronounced compared to spot welding. The metal plates constituting the plate set 11 are more preferably steel plates with a tensile strength of 1180 MPa or more, and even more preferably 1500 MPa or more. The upper limit of the tensile strength is not particularly limited, but may be, for example, 2700 MPa or less. Furthermore, the metal plates constituting the plate set 11 may be aluminum plates, titanium plates, or the like. Unlike joining by welding, in riveting according to this embodiment, the metal plates constituting the plate set 11 may be made of different materials. For example, a combination of a steel sheet and an aluminum sheet, or a combination of a steel sheet and a titanium sheet may be used. The metal sheet may be subjected to various surface treatments. For example, the metal sheet may be GA plated, GI plated, EG plated, Zn-Mg plated, Zn-Al plated, Zn-Ni plated, Zn-Al-Mg plated, Al plated, painted, or may have a Zn-based plating (Zn-Fe, Zn-Ni-Fe) or an Al-based plating (Al-Fe-Si) alloyed with the base metal by hot stamping.

[0054] The thickness of the metal plates is not particularly limited and may be, for example, 0.5 mm to 3.6 mm. The thicknesses of the metal plates constituting the plate assembly 11 may be different. Suitable combinations include, for example, a two-ply combination of a plate material having a thickness of approximately 1.6 mm and a plate material having a thickness of approximately 2.3 mm, or a three-ply combination of a plate material having a thickness of 0.75 mm, a plate material having a thickness of 1.8 mm, and a plate material having a thickness of 1.2 mm. Suitable combinations of plate materials include, for example, a two-ply combination of a plate material having a thickness of approximately 0.6 mm to 2.9 mm and a plate material having a thickness of 0.6 mm to 2.9 mm, or a three-ply combination of a plate material having a thickness of 0.6 mm to 1.6 mm, a plate material having a thickness of 0.6 mm to 2.9 mm, and a plate material having a thickness of 0.6 mm to 2.9 mm. The plate materials may be molded products obtained by cold or hot press forming, cold roll forming, hydroforming, or hot blow molding. The plate material may also be formed into a pipe shape. For example, when the thickness of the target material is 1.6 mm or less, it is preferable to set the height H1 of the first rising portion 1112 to a value greater than the thickness of the target material, so that the tip of the first rising portion 1112 protrudes from the first surface X of the target material. Note that when there are two or more target materials, the thickness of the target materials means the total thickness of the target materials.

[0055] The shape of the through hole can be, for example, circular. Alternatively, the shape of the through hole may be polygonal, such as quadrilateral, pentagonal, hexagonal, or octagonal. The corners of these polygons may be curved. The shape of the through hole may also be elliptical or a shape with a convex or concave portion on a part of a circle. Making the through hole a shape other than circular is more desirable because it can prevent the joined metal plates from rotating around the joining member of the through hole and reduce rattle at the joint. The above-mentioned examples of the shape of the through hole can also be applied to the shape of the raised portion when viewed along a direction perpendicular to the metal plates.

[0056] The joining member 12 is not particularly limited as long as it has a shaft portion 123 and a first protrusion 121 and a second protrusion 122 that are protrusions on both ends of the shaft portion. For example, the joining member 12 may be a combination of a bolt and a nut. The flange portion of the bolt and the nut form a pair of protrusions of the joining structure 1 according to this embodiment. The joining member 12 may also be a rivet. A rivet has a shaft portion and a flange-shaped head provided at one end of the shaft. When joining metal plates using a rivet, first the shaft portion is inserted into a through-hole, and then the other end of the shaft is plastically deformed to form a plastically deformed portion. This series of steps is known as riveting. The head and plastically deformed portion form the protrusions of the joining structure 1 according to this embodiment.

[0057] Riveting is preferable because it can be performed using a riveter or spot welder and can be completed in a short time. Furthermore, the plastically deformed portion formed by riveting has a shape corresponding to the shape of the joined materials. For example, a configuration in which a first raised portion 1112 and / or a second raised portion 1122 protrude from the surface of the sheet assembly 11 and a second protruding portion 122 is formed to cover these raised portions, as shown in Figures 5B, 5C, 6B, and 6C, can be easily formed by riveting. In this case, riveting can be performed by placing the rivet head on the base side of the first raised portion 1112. On the other hand, a configuration in which a first protruding portion 121 fills the space surrounded by a tapered curved surface formed at the base of the first raised portion 1112, as shown in Figure 7, can also be easily formed by riveting. In this case, riveting can be performed by placing the rivet head on the top side of the first raised portion 1112.

[0058] The material and thickness of the shaft portion 123 of the joining member 12 are not particularly limited and can be selected appropriately depending on the joining strength required for the joining structure 1. For example, when the joining structure 1 is an automobile part and the metal plate is a high-strength steel plate, the thickness of the shaft portion of the joining member 12 is preferably 3 mm or more, 4 mm or more, or 5 mm or more. This allows the joining structure 1 to be provided with the joining strength required for automobile parts. The thickness of the shaft portion 123 is the minimum value of the width of the shaft portion 123 measured along a direction perpendicular to the axis in a cross section including the axis of the joining member 12.

[0059] When the joining member 12 is a rivet, the shape of the rivet head may be a common flange shape. For example, the shape of the rivet head may be hemispherical (so-called round head), disc-shaped (so-called flat head), or a shape with a flat surface and a conical base (so-called countersunk head). The shape of the rivet head in plan view may be, for example, circular, rectangular, hexagonal, or other polygonal shape. A positioning recess may be provided in the center of the electrode side of the rivet head. Furthermore, the seat of the rivet head (the surface that contacts the workpieces) may be provided with a recess surrounding the shank (so-called seat undercut). Such a recess imparts elasticity to the rivet head, thereby further increasing the rivet's crimping force. Furthermore, the seat of the rivet head (the surface that contacts the workpieces) may be provided with one or more flange protrusions. Such flange projections further increase the clamping force of the rivet by sinking into the joined materials during riveting or by forming a joint with the joined materials. The flange projections can be circular, polygonal, or ring-shaped, surrounding the shank.

[0060] The material of the joining member 12 is not particularly limited. A material according to the required joining strength can be used for the joining member 12. Examples of suitable materials for the joining member 12 include steel, stainless steel, aluminum, and titanium. The joining member 12 may not be surface-treated. On the other hand, if corrosion resistance is required for the joining structure 1, the joining member 12 may be surface-treated. For example, the joining member 12 may be zinc-based plated, aluminum-based plated, chromium-based plated, nickel-based plated, or chromate-treated.

[0061] The size of the pair of protrusions of the joining member 12 is not particularly limited. The protrusions can be sized according to the size of the through holes and the required joining strength, as long as the plate assembly 11 can be joined. While a typical joining member requires the diameter of the protrusions to be larger than the diameters of the through holes in all of the metal plates, the joining structure 1 according to this embodiment may allow the diameter of the protrusions to be smaller than the diameters of the through holes in some of the metal plates. As illustrated in FIG. 6A , the joining structure 1 according to this embodiment can join the metal plates using raised portions. In this case, the diameter of the through holes in the metal plates fixed by the raised portions may be larger than the diameter of the protrusions. However, to prevent the joining member 12 from falling off, it is preferable that the diameter of the protrusions be larger than the diameter of the narrowest part of the internal space of the first raised portion 1112 and / or the internal space of the through hole.

[0062] In the joining structure 1 according to this embodiment, the joining member 12 may be combined with another joining means to join the multiple metal plates. For example, the joining structure 1 may further include an adhesive disposed on one or more of the mating surfaces of the multiple metal plates. This can further increase the joining strength of the joining structure 1. Also, a sealer may be disposed on one or more of the mating surfaces of the multiple metal plates. This can increase the corrosion resistance of the joining structure 1. The joining structure 1 may further include welds such as spot welds and laser welds that join the multiple metal plates. [Example]

[0063] The effects of one embodiment of the present invention will be explained in more detail using examples. However, the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention. The present invention is not limited to these examples. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.

[0064] In order to confirm the effect of the present invention, the resistance of the joint structures A to D to in-plane tensile stress was analyzed by simulation. Joint structure A: A conventional example in which two metal plates without raised portions are joined with rivets. Joint structure B: An example of the present invention in which a first metal plate having a first raised portion and a target material (flat metal plate) having no raised portion are joined with rivets. Joint structure C: An example of the present invention in which a first metal plate having a first raised portion and a target material (second metal plate) having a second raised portion are joined with a rivet. · Joint structure D: A reference example in which the target material has been removed from joint structure B. The analysis results are shown in Figure 8.

[0065] In all of the joint structures B to D, an in-plane tensile stress was applied to the first metal plate on which the first raised portion was formed. In the conventional joint structure A, which did not have a first raised portion, an in-plane tensile stress was applied to the lower plate. For reference, arrows indicating the direction in which the in-plane tensile stress was applied are attached to the cross-sectional views of these joint structures. The magnitude of the in-plane tensile stress was determined so that the inner diameter of the first raised portion or the overall length of the lower plate increased by 2 mm in the direction in which the in-plane tensile stress was applied.

[0066] The "Side View Analysis Results" in Figure 8 are analysis results of a metal plate to which in-plane tensile stress has been applied, displayed in a side view. The "Plane View Analysis Results" in Figure 8 are analysis results of a metal plate to which in-plane tensile stress has been applied, displayed in a plan view. Metal plates to which in-plane tensile stress has not been applied are not shown in these analysis results.

[0067] In both Joint Structure B and Joint Structure C, the equivalent plastic strain was suppressed to a lower level than in Joint Structure A. In addition, the equivalent plastic strain in the joint structure having the second rising portion was suppressed to an even lower level than in Joint Structure B.

[0068] The equivalent plastic strain of Reference Example D, a joint structure without the target material, was at a higher level than that of Joint Structure B, which had the target material. According to the analysis results of Joint Structure D, it is believed that the through hole of the target material has the effect of reducing the equivalent plastic strain of the first metal plate by covering the first rising portion and suppressing its deformation. [Explanation of symbols]

[0069] 1 Joint structure 11 Board set 111 First Metal Plate 1111 First through hole 1112 First rising part 112 Second metal plate (target material having a rising portion) 1121 Second through hole 1122 Second rising part 113 Flat metal plate (material without raised portion) 1131 Through holes in flat metal plates 12 Joint materials 121 First protrusion 122 Second protrusion 123 Shaft X First surface of the target material

Claims

1. a first metal plate having a cylindrical first rising portion formed thereon; one or more target materials having through holes through which the first rising portions are inserted and joined to the first metal plate; a joining member that is inserted into the first rising portion and joins the overlapping first metal plate and the target material; A joining structure comprising: the joining member has a shaft portion inserted into the first rising portion, a first surface, which is a surface opposite to a surface facing the first metal plate among both surfaces of the target material, and a tip end of the first rising portion are at different positions in the axial direction of the first rising portion, At least one of the target materials is a second metal plate having a second rising portion, the second rising portion is a cylindrical region rising from an edge portion of the second through-hole, which is the through-hole provided in the second metal plate, The first rising portion is inserted between the second rising portion and the shaft portion. A joining structure characterized by:

2. The joining member is provided on both ends of the shaft portion and has a pair of protrusions that protrude radially outward from the shaft portion, thereby joining the first metal plate and the target material. The joining structure according to claim 1 .

3. the second rising portion is obtained by bending the second metal plate, the first rising portion and the second rising portion rise in the same direction, In a direction perpendicular to the first metal plate, the tip of the first rising portion is farther from the first metal plate than the tip of the second rising portion. The joint structure according to claim 1 or 2.

4. a first metal plate having a cylindrical first rising portion formed thereon; one or more target materials having through holes through which the first rising portions are inserted and joined to the first metal plate; a joining member that is inserted into the first rising portion and joins the overlapping first metal plate and the target material; A joining structure comprising: the joining member has a shaft portion inserted into the first rising portion, a first surface, which is a surface opposite to a surface facing the first metal plate among both surfaces of the target material, and a tip end of the first rising portion are at different positions in the axial direction of the first rising portion, the joining member is provided on both ends of the shaft portion and has a pair of protrusions protruding radially outward from the shaft portion, thereby joining the first metal plate and the target material; an internal space of the first rising portion has a curved shape that narrows from a base portion to a top portion of the first rising portion; The protruding portion of the joining member, which is disposed on the base side of the first rising portion, has a curved shape that follows the inner surface of the first rising portion. A joining structure characterized by:

5. a first metal plate having a cylindrical first rising portion formed thereon; one or more target materials having through holes through which the first rising portions are inserted and joined to the first metal plate; a joining member that is inserted into the first rising portion and joins the overlapping first metal plate and the target material; A joining structure comprising: the joining member has a shaft portion inserted into the first rising portion, a first surface, which is a surface opposite to a surface facing the first metal plate among both surfaces of the target material, and a tip end of the first rising portion are at different positions in the axial direction of the first rising portion; the number of the first metal plates is one, the joining member is provided on both ends of the shaft portion and has a pair of protrusions protruding radially outward from the shaft portion, thereby joining the first metal plate and the target material; the first raised portion protrudes from the first surface of the target material, A joining structure in which the protruding portion of the joining member arranged on the side of the first surface of the target material covers the first rising portion protruding from the first surface of the target material.

6. The joining structure according to claim 5, characterized in that the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material.

7. The second rising portion protrudes from the first surface of the target material. The joint structure according to claim 1 or 2.

8. The joining structure described in claim 7, characterized in that the protruding portion of the joining member arranged on the side of the first surface of the target material covers the second rising portion protruding from the first surface of the target material.

9. The joining structure according to claim 8, characterized in that the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material.

10. Both the first raised portion and the second raised portion protrude from the first surface of the target material. The joint structure according to claim 1 or 2.

11. The joining structure described in claim 10, characterized in that the protruding portion of the joining member arranged on the side of the first surface of the target material covers both the first rising portion and the second rising portion protruding from the first surface of the target material.

12. The joining structure according to claim 11, characterized in that the protruding portion of the joining member arranged on the side of the first surface of the target material is in contact with the first surface of the target material.

13. A first metal plate having a cylindrical first rising portion formed thereon; one or more target materials having through holes through which the first rising portions are inserted and joined to the first metal plate; a joining member that is inserted into the first rising portion and joins the overlapping first metal plate and the target material; A joining structure comprising: the joining member has a shaft portion inserted into the first rising portion, a first surface, which is a surface opposite to a surface facing the first metal plate among both surfaces of the target material, and a tip end of the first rising portion are at different positions in the axial direction of the first rising portion; the number of the first metal plates is one, the joining member is provided on both ends of the shaft portion and has a pair of protrusions protruding radially outward from the shaft portion, thereby joining the first metal plate and the target material; the joining member is a rivet, A joining structure further comprising an adhesive disposed on the mating surfaces of the first metal plate and the target material.

14. A first metal plate having a cylindrical first rising portion formed thereon; one or more target materials having through holes through which the first rising portions are inserted and joined to the first metal plate; a joining member that is inserted into the first rising portion and joins the overlapping first metal plate and the target material; A joining structure comprising: the joining member has a shaft portion inserted into the first rising portion, a first surface, which is a surface opposite to a surface facing the first metal plate among both surfaces of the target material, and a tip end of the first rising portion are at different positions in the axial direction of the first rising portion; the number of the first metal plates is one, the joining member is provided on both ends of the shaft portion and has a pair of protrusions that protrude radially outward from the shaft portion, thereby joining the first metal plate and the target material; the joining member is a rivet, A joining structure further comprising an adhesive disposed on one or more of the mating surfaces between the first metal plate and the target material and the mating surfaces between the plurality of target materials.

Images