Joint structure

Abstract

To provide a joint structure that can ensure a preferable joining strength according to a plate thickness of a target material to be joined to a base material.SOLUTION: A joint structure according to an embodiment of the present invention comprises: a first metal plate that is formed with a cylindrical first raised portion; one or more target materials that are formed with a through hole through which the first raised portion is inserted, and are joined to the first metal plate; and a joining member that is inserted into the first raised portion and joins the first metal plate and the target material, which are overlapped with each other. The joining member has a shaft portion inserted into the inside of the first raised portion. The number of first metal plates is one. The joining member has a pair of protrusions that are provided on both ends of the shaft portion and protrude toward a radially-outward direction of the shaft portion, thereby joining the first metal plate and the target material. The joining member is a rivet, the first raised portion protrudes from a first surface of the target material, and an angle of the first raised portion is greater than or equal to 45° and less than 90°.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a joining structure in which a base material formed with a burring portion 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 in Japan on June 29, 2021, and incorporates its contents herein by reference.

Background Art

[0002] For the purpose of weight reduction of automobiles and improvement of collision safety, the application of high-strength steel sheets is being promoted. However, spot weld joints composed of high-strength steel sheets have a problem that the joining strength decreases as the tensile strength of the base metal steel sheet increases. For example, when the tensile strength of the base metal steel sheet exceeds 780 MPa, there is a problem that the cross-tension strength (CTS) decreases. Further, when the tensile strength of the steel sheet exceeds 1500 MPa, not only the cross-tension strength but also the tensile shear strength (TSS) tends to decrease.

[0003] The cross-tension strength means the strength of the joint with respect to the peeling direction stress. The stress in the peeling direction is the stress applied to the joint by pulling two or more metal plates constituting the joining structure in a direction perpendicular to the plate surface and away from each other. The tensile shear strength is the strength of the joint with respect to the shear stress. The shear stress is the stress applied to the joint by pulling two metal plates constituting the joining structure in a direction parallel to the plate surface and away from each other. The cross-tension strength (CTS) is measured in accordance with JIS Z 3137:1999, and the tensile shear strength (TSS) is measured in accordance with JIS Z 3136:1999.

[0004] The decrease in joint strength is caused by embrittlement of the nugget formed in a high-strength steel sheet with a high carbon content. In high-strength steel sheets, toughness is ensured by applying heat treatments under various conditions to optimize the metal structure. However, when spot welding a high-strength steel sheet, the metal structure changes in the nugget and the heat-affected zone around it, resulting in embrittlement of the joint portion.

[0005] When the strength of a spot-welded joint decreases, there is a risk of breakage at the welded part when the member is deformed due to a collision under very severe conditions. Therefore, even if the strength of the steel sheet is improved, there is a risk that the load-bearing capacity of the entire member will be insufficient. Thus, a joining method for improving the strength of joints composed of high-strength steel sheets is required.

[0006] By the way, as a means for joining plate-like members, in addition to welding, there is mechanical joining using joining members such as rivets. Regarding the joining structure obtained by mechanical joining, for example, the following technologies are disclosed.

[0007] Patent Document 1 discloses a joining structure of a thin plate in which a coupling shaft body is inserted into coupling holes formed in the thin plate and its adherend, and the thin plate and the adherend are tightened by the coupling shaft body and a fixing portion integral with or separate from it to join the thin plate to the adherend. A joining structure of a thin plate is characterized in that a cylindrical flange is continuously provided around the coupling hole formed in the thin plate, and a bag-shaped portion that fits on the outer periphery of the cylindrical flange is provided in the coupling shaft body or the fixing portion. Further, as a conventional example of a joining structure in which a base material having a burring portion and a target material to be joined are joined by a joining member, Patent Document 2 discloses a joining structure of plate materials in a vehicle in which thin plates and thick plates stacked on each other are joined through fastening means passed through through-holes provided in each of them, characterized in that the through-holes in the thin plates are formed in a burring shape having a cylindrical portion. This joining structure is configured to form an insertion hole in the target material through which the burring portion of the base material is inserted, insert the burring portion into the insertion hole, and join the target material to the base material with a joining member having a shaft portion formed with an outer peripheral surface that contacts the inner peripheral surface of the burring portion in a state where the target material and the base material are stacked.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] As one means for improving the cross-tensile strength of a joint, the inventors focused on rivet joining. Rivet joining is a joining method in which a through-hole is formed in a metal plate, a rivet having a head and a shaft is inserted through this through-hole, the tip of the shaft of the rivet is plastically deformed, and the metal plate is caulked by the head and the plastically deformed portion of the rivet. The inventors found that the cross-tensile strength of a joint (rivet joint) obtained by rivet-joining high-strength steel plates is significantly higher than that of a spot-welded joint. According to rivet joining, which mechanically joins steel plates, embrittlement of the joint portion does not occur, so it is considered that the CTS of a joint composed of high-strength steel plates can be kept high. On the other hand, according to the experiments of the inventors, it was also clarified that rivet joints do not function to improve the tensile shear strength (TSS).

[0010] In the technology of Patent Document 1, means for improving TSS in rivet joining has not been studied. In Patent Document 1, the object is to provide a joining structure for thin plates capable of joining members made of thin plates with high strength and rigidity, but the direction of the stress applied to the joining shaft body has not been particularly studied, and therefore, no study has been made focusing on the improvement of TSS. Also, a configuration for improving TSS is not disclosed in Patent Document 1.

[0011] According to the joining structure of Patent Document 2, since the outer peripheral surface of the shaft portion of the joining member is in contact with the inner peripheral surface of the burring portion, when a load that separates the target material and the base material constituting the plate assembly from each other is externally applied, the load in the direction orthogonal to the axial center direction of the load acting on the joining member, that is, the load in the direction of shearing the shaft portion, is transmitted from the inner peripheral surface of the burring portion. Therefore, the load can be dispersed by the length in the axial center direction of the contact area between the inner peripheral surface and the shaft portion, and the stress concentration generated in the shaft portion is alleviated compared to the case where the target material and the base material without the burring portion are simply joined by the joining member. Therefore, improvement of TSS and CTS of the joining structure can be expected. However, in the case of a joining structure in which the first surface, which is the surface on the opposite side of the surface facing the base material among the two surfaces of the target material, and the tip of the burring portion are in the same position in the axial center direction of the burring portion, depending on the combination of the plate thickness of the target material and the plate thickness of the base material, there are problems that the joining structure cannot be appropriately configured and problems that are disadvantageous for the load in the direction of shearing the shaft portion. For example, when the plate thickness of the target material is thick, it is necessary to increase the axial length of the burring portion, in other words, to form a burring portion with a high height. Depending on the material properties of the base material (e.g., hole expandability) and the plate thickness of the base material, cracks may occur in the material during the burring process, resulting in a problem that a burring portion with a height corresponding to the first surface of the target material cannot be formed. Also, for example, when the plate thickness of the target material is thin, the height of the burring portion will be correspondingly low, so the axial length of the inner peripheral surface of the burring portion that contacts the shaft portion is limited. As a result, there is a problem that the area of the inner peripheral surface that contacts the shaft portion is limited, which is disadvantageous for the load in the direction of shearing the shaft portion. As described above, in the joining structure in which the first surface, which is the surface on the opposite side of the surface facing the base material among the two surfaces of the target material, and the tip of the burring portion are in the same position in the axial direction of the burring portion, there is a problem that it is not necessarily a preferable joining structure in terms of joining strength when considering the plate thickness of the target material to be joined to the base material.

[0012] In view of the above situation, a joining structure that can ensure a preferable joining strength according to the plate thickness of the target material to be joined to the base material is desired.

Means for Solving the Problem

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

[0014] (1) The joining structure according to one aspect of the present invention includes a first metal plate in which a cylindrical first rising portion is formed, one or more target materials in which a through hole through which the first rising portion is inserted is formed and which are joined to the first metal plate, and a joining member that is inserted through the first rising portion and joins the overlapped first metal plate and the target materials. The joining member has a shaft portion inserted inside the first rising portion, and the first surface, which is the surface on the opposite side of the surface facing the first metal plate among the two surfaces of the target material, and the tip of the first rising portion are in different positions in the axial direction of the first rising portion. (2) In the joining structure described in (1) above, preferably, the joining member is provided at both ends of the shaft portion and has a pair of protruding portions protruding in the radially outer direction of the shaft portion, whereby the first metal plate and the target material are joined. (3) In the joining structure described in (1) or (2) above, preferably, one or more of the target materials are second metal plates having second rising portions, and the second rising portions are cylindrical regions rising from the edges of second through holes, which are the through holes provided in the second metal plates, and the first rising portion is inserted between the second rising portion and the shaft portion. (4) In the joining structure described in (3) above, preferably, the second rising portion is obtained by bending and forming 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 space inside the first rising portion has a curved surface shape that becomes narrower from the base to the top of the first rising portion, and the protruding portion of the joining member arranged on the base side of the first rising portion has a curved surface shape along the inner surface of the first rising portion. (7) In the joining structure described in any one of (2) to (6) above, preferably, the first rising portion protrudes from the surface of the plate assembly constituting the joining member and has a shape expanded along the surface of the plate assembly, and the protruding portion of the joining member in contact with the first rising portion fixes the plate assembly via the first rising portion. (8) In the joining structure described in any one of (1) to (7) above, preferably, the first rising portion 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 disposed 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 disposed 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 joining structure described in any one of (3) to (7) above, preferably, the second rising portion protrudes 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 disposed 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 disposed 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 joining structure described in 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 disposed 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 disposed on the side of the first surface of the target material is in contact with the first surface of the target material. (17) The joining structure described in any one of (1) to (16) above preferably further includes an adhesive disposed on one or more of the mating surfaces of the plurality of metal plates.

Advantages of the Invention

[0015] According to the joining structure of the present invention, a preferable joining strength can be ensured according to the plate thickness of the target material to be joined to the base material.

Brief Description of the Drawings

[0016]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 5C

Figure 6A

Figure 6B

Figure 6C

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0017] Hereinafter, with reference to the drawings, the joining structure according to this embodiment will be described. As shown in FIGS. 1A and 1B, the joining structure 1 according to the first configuration of the present application includes a first metal plate 111 in which a cylindrical first rising portion 1112 is formed, and a through hole 1131 through which the first rising portion 1112 is inserted is formed and is joined to the first metal plate 111, one or more target materials (the second metal plate 112 or the flat metal plate 113), and a joining member 12 that is inserted through the first rising portion 1112 and joins the overlapped first metal plate 111 and the target material. The joining member 12 has a shaft portion 123 inserted inside the first rising portion 1112, and a first surface X, which is the surface on the opposite side of the two surfaces of the target material facing the first metal plate 111, and the tip of the first rising portion 1112 are at different positions in the axial direction of the first rising portion 1112.

[0018] The first metal plate 111 may hereinafter be referred to as the "base material". The first metal plate 111 is provided with a cylindrical first rising portion 1112. The first rising portion 1112 is, for example, a flanging portion.

[0019] The target material has a through hole 1131 through which the first rising portion 1112 is inserted and is a metal plate joined to the base material, that is, 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 the "second metal plate 112", and the target material having no rising portion joined to the first metal plate 111 is referred to as the "flat metal plate 113". In other words, the target material is · the second metal plate 112 in which the first rising portion 1112 is inserted and a cylindrical rising portion is formed, and · The first rising part 1112 is inserted, and a flat metal plate 113 in which a cylindrical rising part is not formed is a superordinate concept of. In the joining structure 1 illustrated in FIGS. 1A and 1B, the target material through which the first rising part 1112 is inserted corresponds to the flat metal plate 113 because it has no rising part. The joining member 12 has a shaft part 123 inserted inside the first rising part 1112. Since the first rising part 1112 is inserted into the through hole of the target material, naturally, the shaft part 123 inserted inside the first rising part 1112 is also inserted into the through hole of the target material. The shaft center of the shaft part 123 may coincide with the shaft center of the burring part.

[0020] Of the two surfaces of the target material, the first surface X, which is the surface on the opposite side of the surface facing the first metal plate 111, and the tip of the first rising part 1112 are at different positions in the axial direction of the first rising part 1112. Here, the "two surfaces of the target material" means the two surfaces of the target material when there is one target material, and when there are two or more target materials, it means the two surfaces of a group of target materials that are stacked and into which the first rising part 1112 is inserted. That is, the "two surfaces of the target material" is a concept that does not include the mating surface of two target materials. And, 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 rising part 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 will also exist on the sides of both surfaces of the first metal plate 111. The statement that "the first surface X and the tip of the first rising 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 rising portion 1112 do not exist on the same plane perpendicular to the axial direction. In FIG. 1A, the tip of the first rising portion 1112 is inside the through-hole of the target material. In FIG. 1B, the tip of the first rising portion 1112 protrudes outside the through-hole of the target material. In either of the configurations shown in FIGS. 1A and 1B, the first surface X and the tip of the first rising portion 1112 are at different positions in the axial direction.

[0021] The operation and effect of the joining structure 1 according to the first configuration of the present application will be described as follows. According to the first configuration of the present application, since the first surface X, which is the surface on the opposite side of the surface facing the base material among the two surfaces of the target material, and the tip of the burring portion are at different positions in the axial direction of the burring portion, even when the plate thickness of the target material is thick, it is not necessary to adjust the height of the burring portion according to the plate thickness of the target material, and it is sufficient to form a burring portion having a height appropriate for the material characteristics (e.g., hole expandability) of the base material and the plate thickness of the base material. In this case, without aligning the position of the tip of the burring portion and the position of the first surface X of the target material to be the same in the axial direction, even if the tip of the burring portion is positioned closer to the base material side in the axial direction than the first surface X, when the plate thickness of the target material is thick, a burring portion having a sufficient height can be formed. Therefore, when the plate thickness of the target material is thick, by positioning the tip of the burring portion closer to the base material side in the axial direction than the first surface X, it is possible to ensure the joining strength while avoiding cracking of the burring portion. Further, according to the first configuration of the present application, since the first surface X, which is the surface on the opposite side of the surface facing the base material among the two surfaces of the target material, and the tip of the burring portion are different in the axial direction of the burring portion, even when the thickness of the target material is thin, it is not necessary to adjust the height of the burring portion to the thickness of the target material, and a burring portion with a high height can be formed regardless of the thickness of the target material, and a burring portion with a height protruding beyond the first surface X of the target material can be formed. As a result, when a load that separates the target material and the base material constituting the plate assembly 11 from each other is externally applied, the area of the inner peripheral surface of the burring portion that contacts the shaft portion 123 can be increased in the axial direction, and the load in the direction of shearing the shaft portion 123 can be appropriately dispersed, ensuring the strength as a joining 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 on the opposite side of the opposing surface facing the base material among the two surfaces of the target material, and the tip of the burring portion are in different positions in the axial direction of the burring portion, favorable joining strength can be ensured according to the thickness of the target material to be joined to the base material.

[0022] Hereinafter, a specific example of the joining structure 1 according to the present embodiment and an example of a more preferable aspect will be described in detail. The joining structure 1 according to the present embodiment includes a plate assembly 11 in which a plurality of metal plates are stacked, and a joining member 12 that joins the plate assembly 11. Each of the metal plates included in the plate assembly 11 is provided with a through hole, and these through holes are aligned. The plurality of 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 protruding portions provided at both ends of the shaft portion 123 and protruding in the radially outer direction of the shaft portion 123. In the present embodiment, for convenience, the protruding portion on the base side of the first rising portion 1112 described later may be referred to as the first protruding portion 121, and the protruding portion on the top side of the first rising portion 1112 may be referred to as the second protruding portion 122, but both are equivalent. The dashed lines shown in FIGS. 1A and 1B are approximate boundary lines between the shaft portion 123 and the first protruding portion 121 and the second protruding portion 122. In the joining member 12, the first protruding portion 121 and the second protruding portion 122 are portions that protrude radially from the shaft portion 123 at the end of the shaft portion 123 and occupy a ring-shaped region. The shaft portion 123 is inserted through a through hole. The joining member 12 joins a plurality of metal plates of the plate assembly 11 using these pair of protruding portions. 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 joining structure 1 according to the present embodiment, one of the plurality of metal plates has a first rising portion 1112. Hereinafter, the metal plate having the first rising portion 1112 is referred to as a first metal plate 111. Further, the above-described through hole provided in the first metal plate 111 is referred to as a first through hole 1111. Also, a metal plate provided without a rising portion is referred to as a flat metal plate 113. Hereinafter, the joining structure 1 will be described by taking the plate assembly 11 combining the first metal plate 111 and the flat metal plate 113 as an example.

[0023] The first rising portion 1112 is a region having a cylindrical shape formed at 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. And the first rising portion 1112 is inserted between the edge of the through hole of the 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 the metal plate stacked on the first metal plate 111, and the shaft portion 123 is inserted into the first rising portion 1112. In FIG. 1, the first rising portion 1112 is inserted into the through hole 1131 of the 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 the two metal plates included in the plate group 11 of the joining structure 1 are pulled in a direction parallel to the plate surface and away from each other, the first rising portion 1112 exerts an effect of preventing the breakage of the shaft portion 123. The reason will be described below with reference to FIGS. 2A and 2B. The arrows shown in FIG. 2A indicate the shear stress applied to the shaft portion 123 in a conventional joining structure without a rising portion when the upper metal plate is pulled leftward while pulling the lower metal plate rightward. The arrows shown in FIG. 2B indicate the shear stress applied to the shaft portion 123 in the joining structure 1 according to the present embodiment when the upper metal plate, i.e., the flat metal plate 113, is pulled leftward while pulling the lower metal plate, i.e., the first metal plate 111, rightward. As shown in FIG. 2A, in the conventional joining structure, the contact area between the metal plate, which is the object applying the shear stress to the shaft portion 123, and the shaft portion 123 is small. Therefore, the shear stress per unit contact area applied to the shaft portion 123 is large. On the other hand, as shown in FIG. 2B, in the joining structure 1 provided with the first rising portion 1112, the contact area between the first rising portion 1112, which is the object applying the shear stress to the shaft portion 123, and the shaft portion 123 is large. Therefore, the shear stress per unit contact area applied to the shaft portion 123 is alleviated, and the breakage of the shaft portion 123 is suppressed. For the above reasons, the joining structure 1 having the first rising portion 1112 has a dramatically higher TSS compared to the conventional joining structure. In addition, the first rising portion 1112 also functions to facilitate the alignment of the through holes. When a plurality of metal plates with pre-formed through holes are stacked and then the joining member 12 is inserted into the through holes, alignment of the plurality of through holes is required. Here, by inserting the first rising portion 1112 into the through holes of the metal plates stacked on the first metal plate 111, alignment of the through holes can be achieved.

[0025] And as described above, in the joining structure 1, the first surface X, which is the surface on the opposite side of the target material from the surface facing the first metal plate 111 among the two surfaces of the target material, and the tip of the first rising portion 1112 are at different positions in the axial direction of the first rising portion 1112. Thereby, it is not necessary to adjust the plate thickness of the target material and the length of the first rising portion 1112. A rising portion having a height suitable for the material characteristics and various configurations such as the plate thickness of the first metal plate 111 can be freely formed on the first metal plate 111.

[0026] In the joining structure 1 according to the present embodiment, the rising portion may be provided only on the first metal plate 111. In other words, the plate assembly 11 of the joining 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 plate can be reduced. On the other hand, as shown in FIG. 3, two or more rising portions may be formed in the joining 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, the metal plate having the second rising portion 1122 will be referred to as the second metal plate 112. Also, the above-described 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. Further, 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 joining member 12. In the joining structure 1 illustrated in FIG. 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 acceptable in the joining structure 1 according to the present embodiment. The second rising portion 1122 is considered not to be included in the surface of the second metal plate 112.

[0027] Here, for reference, in this embodiment, the member names are defined as follows to distinguish the first metal plate 111, the second metal plate 112, and the flat metal plate 113. · The first metal plate 111: A metal plate having a rising portion, and no other rising portion is inserted inside the rising portion. · The second metal plate 112: A metal plate having a rising portion, and another rising portion is inserted inside the rising portion. · The flat metal plate 113: A metal plate having no rising portion.

[0028] Note that the second metal plate 112 may be included in two or more in the joining structure 1. Also, if there are four or more metal plates constituting the plate set 11, the first metal plate 111 may be included in two or more in the joining structure 1. For example, when two plate sets 11 included in the joining structure 1 shown in FIG. 1 are stacked and joined, a joining structure 1 including two first metal plates 111 can be manufactured.

[0029] Also, the term "metal plate" is used as a concept comprehensively indicating the first metal plate 111, the second metal plate 112, and the flat metal plate 113. Also, the term "target material" is used as a concept comprehensively indicating the second metal plate 112 and the flat metal plate 113. The term "through hole" is used as a concept comprehensively indicating the first through hole 1111, the second through hole 1121, and the through hole 1131 of the flat metal plate, and the term "rising portion" is used as a concept comprehensively indicating the first rising portion 1112 and the second rising portion 1122.

[0030] One of the advantages of providing the second rising portion 1122 is that a rising portion larger than the total plate thickness of the plate set 11 can be provided. Thereby, breakage of the shaft portion 123 can be suppressed. Another advantage of providing the second rising portion 1122 is that the reaction force per contact area applied by the second rising portion 1122 from the first rising portion 1112 can be relaxed. Thereby, breakage of the second rising portion 1122 is suppressed.

[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 joining structure 1 composed of a first metal plate 111 and two flat metal plates 113 stacked thereon. FIG. 4B shows a joining structure 1 composed of a first metal plate 111, a second metal plate 112 stacked thereon, and a flat metal plate 113 stacked thereon. In any case, the rising portion can exhibit the TSS improvement effect. Further, FIG. 4C shows a joining structure 1 composed of a first metal plate 111 and two flat metal plates 113 stacked so as to sandwich this. In FIGS. 1 and the like, the rising portion is provided so as to rise from only one surface of the metal plate, but as illustrated in FIG. 4C, the first rising portion 1112 may be provided so as to rise from both surfaces of the metal plate. Even in this case, the first rising portion 1112 can exhibit the TSS improvement effect. Although not illustrated in the figure, it goes without saying that a flat metal plate 113 may be disposed between the first metal plate 111 and the second metal plate 112, or the first metal plate 111 may be disposed 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 the present embodiment, the number of metal plates included in the plate assembly 11 is not limited, and the first metal plate 111, the second metal plate 112, and the flat metal plate 113 can be variously combined according to the number thereof.

[0032] In FIGS. 1A and the like, the first rising portion 1112 is described as rising perpendicular 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 perpendicular 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 rising portion 1112 satisfies the above requirements, the height H1 of the first rising portion 1112 and the height H2 of the second rising portion 1122 are not particularly limited, but preferred examples will be described below. Here, the height H1 of the first rising portion 1112 is the distance between the surface of the first metal plate 111 on which the first rising portion 1112 is provided and the vertex of the first rising portion 1112, measured along the direction perpendicular to the first metal plate 111. The height H1 is described in FIG. 5A and the like. Similarly, the height H2 of the second rising portion 1122 is the distance between the surface of the second metal plate 112 on which the second rising portion 1122 is provided and the vertex of the second rising portion 1122, measured along the direction perpendicular to the second metal plate 112. As shown in FIG. 5A and the like, 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. Also, 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 and may be more than 0 mm. As long as there is a rising portion even slightly with respect to the plate surface of the metal plate, the rising portion relaxes the shear stress per unit area applied to the shaft portion 123 or the first rising portion 1112 and exhibits the effect of improving the TSS. On the other hand, it is considered that the larger H1 and H2 are, the more the TSS is improved.

[0035] Hereinafter, first, the height H1 etc. of the first rising portion 1112 will be described. Regarding H1, the upper and lower limit values of the height may be determined based on the thickness of the first metal plate 111. For example, H1 may be defined as 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 defined as 200% or less, 180% or less, 150% or less, or 120% or less of the thickness of the first metal plate 111.

[0036] Further, the upper and lower limit values of the height of 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 limit values of the height of 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. In addition, the upper and lower limit values of the height of H1 may be determined based on the thickness of the target material. When the number of target materials is two or more, the thickness of the target material means the total thickness of the plurality of 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 rising portion 1112 protrudes from the surface of the plate set 11, that is, the first surface X of the target material. In this case, the second protruding portion 122 of the joining member 12 does not necessarily contact the metal plate disposed on the surface of the plate set 11. In this case, the metal plate can move in the plate thickness direction of the plate set 11. However, even if the metal plate is not tightly fixed, the first rising portion 1112 can exert an effect of increasing the TSS of the joining structure 1. Further, when the first rising 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 protruding portion 122 of the joining member 12 to suppress rattling of the metal plate.

[0038] As shown in FIG. 5A, the first rising portion 1112 may protrude from the surface of the plate assembly 11 and have a shape that is expanded along the surface of the plate assembly 11. In FIG. 5A, the second protruding portion 122 of the joining member 12 is not in contact with the flat metal plate 113. However, the top of the first rising portion 1112 has a shape that extends in the outer direction of the through-hole along the surface of the plate assembly 11. Therefore, the second protruding portion 122 of the joining member 12 can tightly fix the plate assembly 11 via the first rising portion 1112.

[0039] As shown in FIG. 5B, the first rising portion 1112 may protrude from the first surface of the target material (i.e., the surface of the plate assembly 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 rising portion protruding from the first surface of the target material. In other words, the second protruding portion 122, which is the protruding portion in contact with the top of the first rising portion 1112, may cover the first rising portion 1112. Further, the protruding portion of the joining member (i.e., the second protruding portion 122 of the joining member 12) 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 plate assembly 11). Thereby, the second protruding portion 122 can tightly fix the plate assembly 11. Further, the second protruding portion 122 has the function of further suppressing the detachment of the joining member 12 from the through-hole of the joining structure 1 and further improving the TSS and CTS of the joining structure 1 by preventing the deformation of the first rising portion 1112. For example, the joining member 12 is a rivet, the tip of the rivet is arranged on the top side of the first rising portion 1112, and such a joining structure 1 having such a configuration can be manufactured by plastically deforming this tip. Also, the joining member 12 is a bolt and a nut, and such a joining structure 1 having such a structure can be manufactured by providing a recess capable of accommodating the top of the first rising portion 1112 in the washer portion of the bolt or the nut.

[0040] It is also possible to combine the configurations of FIGS. 5A and 5B. That is, as shown in FIG. 5C, the first rising portion 1112 protrudes from the surface of the plate assembly 11 and has a shape that is expanded along the surface of the plate assembly 11. The second protruding portion 122, which is a protruding portion in contact with the top of the first rising portion 1112, may cover the first rising portion 1112 and also be in contact with the surface of the plate assembly 11.

[0041] Next, the height H2 of the second rising portion 1122 and the like will be described. The lower limit value of H2 is more than 0 mm as described above. Also, 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] Similar to the first rising portion 1112, the second rising portion 1122 may also protrude from the surface of the plate assembly 11. As shown in FIG. 3, when no other metal plate is arranged on the surface of the second metal plate 112, the second rising portion 1122 will necessarily protrude from the surface of the plate assembly 11. On the other hand, as shown in FIG. 4B, when the flat metal plate 113 is arranged on the surface of the second metal plate 112, the top of the second rising portion 1122 does not have to protrude from the plate assembly 11.

[0043] Similar to the first rising portion 1112, as shown in FIG. 6A, the second rising portion 1122 may protrude from the surface of the plate assembly 11 and have a shape that is expanded along the surface of the plate assembly 11. When the flat metal plate 113 is arranged 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. Also, the first rising portion 1112 may be expanded along the surface of the second rising portion 1122.

[0044] Similar to the first rising part 1112, the second rising part 1122 may protrude from the first surface of the target material (i.e., the surface of the plate assembly 11). In this case, the protruding part of the joining member arranged on the side of the first surface of the target material may cover the second rising part protruding from the first surface of the target material. In other words, the second protruding part 122, which is a protruding part in contact with the top of the second rising part 1122, may cover the second rising part 1122. Furthermore, the protruding part 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 plate assembly 11). Thereby, the second protruding part 122 of the joining member 12 can firmly fix the plate assembly 11. Naturally, as shown in FIG. 6B, both the first rising part 1112 and the second rising part 1122 may protrude from the first surface of the target material (i.e., the surface of the plate assembly 11). In this case, the protruding part of the joining member arranged on the side of the first surface of the target material may cover both the first rising part and the second rising part protruding from the first surface of the target material. In other words, the second protruding part 122 of the joining member 12 may cover both the first rising part 1112 and the second rising part 1122. Furthermore, the protruding part 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 plate assembly 11).

[0045] It is also possible to combine the configurations of FIGS. 6A and 6B. That is, as shown in FIG. 6C, one or both of the first rising part 1112 and the second rising part 1122 may protrude from the surface of the plate assembly 11 (i.e., the first surface X of the target material). Furthermore, one or both of the first rising part 1112 and the second rising part 1122 may have a shape expanded along the surface of the plate assembly 11 or the surface of the second rising part 1122. In addition, the second protruding part 122 of the joining member 12 may cover one or both of the first rising part 1112 and the second rising part 1122 protruding from the surface of the plate assembly 11 (i.e., the first surface X of the target material), and may be in contact with the surface of the plate assembly 11 (i.e., the first surface X of the target material).

[0046] Next, the thickness of the rising portion will be described. The thicker the rising portion is, the higher the resistance of the rising portion to the shear stress, which is preferable. 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 plate 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 plate thickness of the second metal plate 112. For example, by welding a metal cylinder to the edge of the through-hole of the metal plate, a rising portion having an arbitrary plate thickness can be formed. The thickness of the first rising portion 1112 is a value measured based on the surface of the two surfaces of the first metal plate on which the first rising portion 1112 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 first metal plate on which the first rising portion 1112 is provided, and the length of the portion of this straight 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 straight line that overlaps with the second rising portion 1122 is regarded as the thickness of the second rising portion 1122.

[0047] The manufacturing method of the rising part is not particularly limited. For example, a metal cylinder having an inner diameter substantially the same as that of the through hole can be welded to the metal plate to form the rising part. When observing the cross section of the joining structure 1 obtained by welding after appropriately preparing it, the presence of the welded part joining the rising part and the metal plate can be confirmed. Further, the rising part may be formed by flanging. Flanging is a machining process in which while perforating a metal plate, the material of the perforated part is extended perpendicular to the surface of the metal plate to form a flange at the edge of the through hole. When observing the cross section of the joining structure 1 obtained by flanging, it can be confirmed that the rising part is obtained by bending, and the rising part and the metal plate are integrally formed.

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

[0049] When forming the rising part by flanging, metal plate thinning may occur. By applying the shape as described above to the joining structure 1, thinning of the second metal plate 112 can be prevented. Thereby, it is possible to suppress breakage of the thinned part when a stress in the peeling direction is applied to the joining structure 1. Therefore, the CTS of the joining structure 1 can be further enhanced.

[0050] The inner diameter of the rising portion may be constant in the direction perpendicular to the metal plate as shown in FIG. 1 and the like. On the other hand, for example, as shown in FIG. 7, the space inside the first rising portion 1112 and / or the second rising portion 1122 may have a curved surface shape that narrows from its base to its top. The rising portion formed by the flanging process often has such a curved surface shape.

[0051] When the space inside the first rising portion has a curved surface shape that narrows from its base to its top, as shown in FIG. 7, the protruding portion (i.e., the first protruding portion 121) arranged on the base side of the first rising portion preferably has a curved surface shape along the inner surface of the first rising portion. In other words, it is preferable that the protruding portion fills the inside of the first rising portion. In this case, the protruding amount of the first protruding portion 121 decreases as it progresses toward the center side of the joining structure 1 in the axial direction. That is, the protruding amount of the first protruding portion 121 continuously decreases in the axial direction. Thereby, the contact area between the shaft portion 123 and the first rising portion 1112 is further enlarged, the shear stress is further dispersed, and the TSS of the joining structure 1 is further improved.

[0052] Various forms can be further applied to the joining structure 1 according to this embodiment.

[0053] The material of the plurality of metal plates constituting the plate group 11 is not particularly limited. For example, when the plurality of metal plates constituting the plate group 11 are steel plates, particularly high-strength steel plates (for example, steel plates with a tensile strength TS of about 590 MPa or more), it is preferable because the strength of the joining structure 1 can be improved. Further, in manufacturing the joining structure 1 according to the present embodiment, embrittlement that causes a decrease in CTS and TSS is not caused in the high-strength steel plate. When the tensile strength of the high-strength steel plate is 980 MPa or more, with respect to CTS, the superiority of the rivet joining according to the present embodiment becomes more prominent with respect to spot welding. The metal plate constituting the plate group 11 is more preferably a steel plate having 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. Further, the metal plate constituting the plate group 11 may be an aluminum plate, a titanium plate, or the like. Different from joining by welding, in the rivet joining according to the present embodiment, the materials of the plurality of metal plates constituting the plate group 11 may be different. For example, a combination of a steel plate and an aluminum plate, or a combination of a steel plate and a titanium plate may be used. Various surface treatments may be performed on the metal plate. For example, the metal plate may have GA plating, GI plating, EG plating, Zn-Mg plating, Zn-Al plating, Zn-Ni plating, Zn-Al-Mg plating, Al plating, painting, and Zn-based plating (Zn-Fe, Zn-Ni-Fe) and Al-based plating (Al-Fe-Si) alloyed with the base metal by hot stamping, etc.

[0054] There is no particular limitation on the thickness of the metal plate either. For example, it may be set to 0.5 mm to 3.6 mm. The thicknesses of the plurality of metal plates constituting the plate set 11 may be different. As a preferable combination, for example, two sheets of a plate material with a thickness of about 1.6 mm and a plate material with a thickness of about 2.3 mm are stacked, or three sheets of a plate material with a thickness of 0.75 mm, a plate material with a thickness of 1.8 mm, and a plate material with a thickness of 1.2 mm are stacked. As the range of a preferable combination of plate materials, for example, two sheets of a plate material with a thickness of about 0.6 mm to 2.9 mm and a plate material with a thickness of 0.6 mm to 2.9 mm are stacked, or three sheets of a plate material with a thickness of 0.6 mm to 1.6 mm, a plate material with a thickness of 0.6 mm to 2.9 mm, and a plate material with a thickness of 0.6 mm to 2.9 mm are stacked. The plate material may be a molded product formed by press molding, roll forming, hydroforming, or hot blow molding, either cold or hot. Further, the plate material may be formed in a pipe shape. For example, when the thickness of the target material is 1.6 mm or less, it is preferable that the height H1 of the first rising portion 1112 is set to a value larger than the thickness of the target material, and the tip of the first rising portion 1112 protrudes from the first surface X of the target material. When there are two or more target materials, the thickness of the target material means the total thickness thereof.

[0055] The shape of the through hole can be, for example, circular or the like. On the other hand, the shape of the through hole may be a polygon such as a quadrilateral, pentagon, hexagon, octagon, etc. A curvature may be provided at the corners of these polygons. Further, the shape of the through hole may be an ellipse, or a shape having a convex portion or a concave portion in a part of a circle. By setting the shape of the through hole to a shape other than a circular shape, it is possible to prevent the joined metal plates from rotating around the joining member of the through hole and to reduce the play at the joint portion, which is more desirable. The examples of the shape of the through hole described above can also be applied to the shape of the rising portion viewed along the direction perpendicular to the metal plate.

[0056] The joining member 12 is not particularly limited as long as it has a shaft portion 123 and first and second protruding portions 121 and 122 which are protruding portions at both ends thereof. 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 serve as a pair of protruding portions of the joining structure 1 according to the present embodiment. Further, the joining member 12 may be a rivet. A rivet has a shaft portion and a flange-shaped head provided at one end of the shaft portion. When joining metal plates using a rivet, first, the shaft portion is inserted through a through-hole, and then a plastic deformation portion is formed by plastically deforming the other end of the shaft portion. These series of steps are so-called riveting. The head and the plastic deformation portion serve as the protruding portions of the joining structure 1 according to the present embodiment.

[0057] Riveting can be carried out using a riveter or a spot welder, and is preferable in that it can be completed in a short time. Further, the plastic deformation portion formed by riveting is preferable in that it has a shape corresponding to the shape of the material to be joined. For example, as shown in FIGS. 5B, 5C, 6B, and 6C, a configuration in which the first rising portion 1112 and / or the second rising portion 1122 protrude from the surface of the plate set 11 and the second protruding portion 122 is formed so as to cover these rising portions can be easily formed by riveting. In this case, the head of the rivet may be arranged on the base side of the first rising portion 1112 and riveting may be performed. On the other hand, for example, as shown in FIG. 7, a configuration in which the first protruding portion 121 is filled in a space surrounded by a tapered curved surface formed at the base of the first rising portion 1112 can also be easily formed by riveting. In this case, the head of the rivet may be arranged on the top side of the first rising portion 1112 and riveting may be performed.

[0058] The material and thickness of the shaft portion 123 of the joining member 12 are not particularly limited and can be appropriately selected according to the joining strength required for the joining structure 1. For example, when the joining structure 1 is an automotive 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. Thereby, the joining strength required for automotive parts can be imparted to the joining structure 1. Note that the thickness of the shaft portion 123 is the minimum value of the width of the shaft portion 123 measured along the direction perpendicular to the shaft center in the cross section including the shaft center of the joining member 12.

[0059] When the joining member 12 is a rivet, the shape of the head of the rivet may be a general flange shape. For example, the shape of the head of the rivet can be a hemispherical shape (so-called round head), a disk shape (so-called flat head), or a shape in which the surface side is flat and the base is conical (so-called pan head). The shape of the head of the rivet in plan view can be, for example, a polygon such as a circle, a square, or a hexagon. A positioning recess may be provided at the center of the electrode side of the head of the rivet. Further, a recess (so-called seat undercut) surrounding the shaft portion may be provided in the seat portion (the surface in contact with the material to be joined) of the head of the rivet. Such a recess imparts elasticity to the head of the rivet, thereby further increasing the caulking force of the rivet. Further, one or more flange protrusions may be provided on the seat portion (the surface in contact with the material to be joined) of the head of the rivet. Such flange protrusions further increase the caulking force of the rivet by sinking into the material to be joined during riveting or forming a joint between the material to be joined and the joint portion. Examples of the shape of the flange protrusion include a circular shape, a polygonal shape, and a ring shape surrounding the shaft portion.

[0060] The material of the joining member 12 is not particularly limited. A material corresponding to the required joining strength can be applied to 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, when the joining structure 1 requires corrosion resistance, the joining member 12 may be surface-treated. For example, the joining member 12 may be subjected to zinc-based plating, aluminum-based plating, chromium-based plating, nickel-based plating, or chromate treatment.

[0061] The size of the pair of protruding portions of the joining member 12 is not particularly limited. Within the range where the plate set 11 can be joined, the size corresponding to the size of the through hole and the required joining strength can be applied to the protruding portions. In a normal joining member, it is necessary for the diameter of the protruding portion to be larger than the diameter of the through holes of all the metal plates. However, in the joining structure 1 according to the present embodiment, there may be a case where the diameter of the protruding portion may be smaller than the diameter of the through holes of some of the metal plates. As illustrated in FIG. 6A, in the joining structure 1 according to the present embodiment, the metal plates can be joined using the rising portions. In this case, the diameter of the through holes of the metal plates fixed by the rising portions may be larger than the diameter of the protruding portion. However, in order to prevent the joining member 12 from falling off, it is preferable that the diameter of the protruding portion is larger than the diameter of the narrowest portion among the internal space of the first rising portion 1112 and / or the internal space of the through holes.

[0062] In the joining structure 1 according to the present embodiment, for joining a plurality of metal plates, the joining member 12 and another joining means may be combined. For example, the joining structure 1 may further have an adhesive disposed on one or more of the mating surfaces of the plurality of metal plates. Thereby, the joining strength of the joining structure 1 can be further enhanced. Also, a sealer may be disposed on one or more of the mating surfaces of the plurality of metal plates. Thereby, the corrosion resistance of the joining structure 1 can be enhanced. The joining structure 1 may further have welding portions such as spot welding portions and laser welding portions for joining a plurality of metal plates.

Examples

[0063] The effects of one aspect of the present invention will be further specifically described by way of examples. However, the conditions in the examples are merely one example adopted to confirm the feasibility and effects of the present invention. The present invention is not limited to this one example. The present invention can adopt various conditions as long as it does not deviate from the gist of the present invention and can achieve the object of the present invention.

[0064] To confirm the effects of the present invention, the resistance to in-plane tensile stress of joining structures A to D was analyzed by simulation. · Joining structure A: A conventional example in which two metal plates without rising portions are joined with rivets. · Joining structure B: An example of the present invention in which a first metal plate having a first rising portion and a target material (flat metal plate) without a rising portion are joined with rivets. · Joining structure C: An example of the present invention in which a first metal plate having a first rising portion and a target material (second metal plate) having a second rising portion are joined with rivets. · Joining structure D: A reference example in which the target material is removed from joining structure B. The analysis results are shown in FIG. 8.

[0065] In any of joining structures B to D, an in-plane tensile stress was applied to the first metal plate in which the first rising portion was formed. In the conventional joining structure A without the first rising 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 is applied are attached to the cross-sectional views of these joining structures. The magnitude of the in-plane tensile stress was determined such that the inner diameter of the first rising portion or the total length of the lower plate increased by 2 mm along the direction in which the in-plane tensile stress is applied.

[0066] The "analysis result in side view" in FIG. 8 is the analysis result of the metal plate to which the in-plane tensile stress is applied, displayed in side view. The "analysis result in plan view" in FIG. 8 is the analysis result of the metal plate to which the in-plane tensile stress is applied, displayed in plan view. In these analysis results, the metal plate to which the in-plane tensile stress was not applied is not displayed.

[0067] In both the joining structure B and the joining structure C, the equivalent plastic strain was suppressed to a level lower than that of the joining structure A. Further, the equivalent plastic strain of the joining structure having the second rising portion was suppressed to a level even lower than that of the joining structure B.

[0068] The equivalent plastic strain of the reference example D of the joining structure without the target material was at a higher level than that of the joining structure B having the target material. According to the analysis result of the joining structure D, it is considered that the through hole of the target material has the effect of covering the first rising portion and suppressing its deformation, thereby reducing the equivalent plastic strain of the first metal plate.

Explanation of Signs

[0069] 1 Joining structure 11 Plate set 111 First metal plate 1111 First through hole 1112 First rising portion 112 Second metal plate (target material having a rising portion) 1121 Second through hole 1122 Second rising portion 113 Flat metal plate (target material without a rising portion) 1131 Through hole of the flat metal plate 12 Joining member 121 First protruding portion 122 Second protruding portion 123 Shaft portion X First surface of the target material

Claims

1. A first metal plate having a cylindrical first rising portion; One or more target materials in which a through hole through which the first rising portion is inserted is formed and which are joined to the first metal plate; A joining member that is inserted through the first rising portion and joins the first metal plate and the target material that are overlapped; A joining structure comprising: The joining member has a shaft portion inserted inside the first rising portion; A first surface, which is a surface on the opposite side of the surfaces of the target material facing the first metal plate, and the tip 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 1; The joining member has a pair of protruding portions provided at both ends of the shaft portion and protruding in the radially outer direction of the shaft portion, thereby joining the first metal plate and the target material; The joining member is a rivet; The angle of the first rising portion forms an angle of 45° or more and less than 90° with respect to the first metal plate Joining structure.

2. The joining member has a pair of protruding portions provided at both ends of the shaft portion and protruding in the radially outer direction of the shaft portion, thereby joining the first metal plate and the target material The joining structure according to claim 1, characterized in that.

3. One or more of the target materials are second metal plates having second rising portions; The second rising portion is a cylindrical region rising from an edge of a 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 The joining structure according to claim 1 or 2, characterized in that.

4. The second rising portion is obtained by bending and forming 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 joining structure according to claim 3, characterized in that.

5. The joining structure according to claim 1 or 2, characterized in that the rising portion is provided only on the first metal plate.

6. The space inside the first rising portion has a curved surface shape that becomes narrower from the base to the top 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 surface shape along the inner surface of the first rising portion. The joining structure according to claim 2, characterized in that.

7. The first rising portion protrudes from the surface of the plate group constituting the joining member and has a shape that is expanded along the surface of the plate group. The protruding portion of the joining member that contacts the first rising portion fixes the plate group via the first rising portion. The joining structure according to claim 2, characterized in that.

8. The first rising portion protrudes from the first surface of the target material. The joining structure according to claim 1, characterized in that.

9. The protruding portion of the joining member, which is disposed 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. The joining structure according to claim 8, characterized in that.

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

11. The second rising portion protrudes from the first surface of the target material. The joining structure according to claim 3, characterized in that.

12. The protruding portion of the joining member, which is disposed 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. The joining structure according to claim 11, characterized in that.

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

14. Both the first rising portion and the second rising portion protrude from the first surface of the target material. The joining structure according to claim 3, characterized in that.

15. The protruding portion of the joining member, which is disposed 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. The joining structure according to claim 14, characterized in that.

16. The protruding portion of the joining member, which is disposed on the side of the first surface of the target material, is in contact with the first surface of the target material. The joining structure according to claim 15, characterized in that.

17. The joining structure according to claim 1 or 2, further comprising an adhesive disposed on one or more mating surfaces of the plurality of metal plates.

Images