Joint of dissimilar materials, method for manufacturing a joint of dissimilar materials, and aluminum member with studs

Abstract

To provide a dissimilar joint reinforcement member in which dissimilar materials are firmly joined to each other, and that can secure excellent corrosion resistance, and a manufacturing method for the dissimilar joint reinforcement member.SOLUTION: In a dissimilar material joint body 100, a studded aluminum member 150 in which a steel stud member 13 is attached to an aluminum material 11, and a steel material 15 are melted and joined to each other. The stud member 13 comprises a head part 31 and a shaft part 33. The shaft part 33 penetrates the aluminum material 11 in a thickness direction and protrudes from the aluminum material 11, and a diameter expansion part expanded outward in a radial direction is formed at a tip of the protruding shaft part 33. A back side surface of the head part 31 opposed to the aluminum material 11 is caulked and joined to the aluminum material. The tip of the shaft part 33 and the steel material 15 are melted and welded so as to form a gap at a desired interval between the aluminum material 11 and the steel material 15.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a dissimilar material joined body, a method for manufacturing the dissimilar material joined body, and a studded aluminum member.

Background Art

[0002] For example, in vehicles such as automobiles, so-called side sills, which are structural members, are provided along the front-rear direction on both sides at the lower part of the vehicle body. As this side sill, in order to enhance energy absorption characteristics, there is one provided with a reinforcing member made of an aluminum extrusion having a closed cross-section structure. In such a side sill, it is necessary to dissimilarly join a reinforcing member made of an aluminum extrusion to a steel material such as a steel plate or a steel section that has been originally widely used as a normal automobile body.

[0003] Patent Document 1 discloses a technique for joining a steel plate mainly composed of iron and a steel plate mainly composed of aluminum by driving a self-piercing rivet (SPR: Self Piercing Riveting) from the side of the steel plate mainly composed of aluminum and expanding a protruding portion in the self-piercing rivet in the steel plate mainly composed of iron.

[0004] Further, Patent Document 2 shows that in a joined body of dissimilar metals of a light alloy steel plate and a steel plate, a convex portion protruding toward the steel plate side on the light alloy steel plate is spot welded to the steel plate, electrodeposition coating is applied to a gap formed by the convex portion, and further, the gap is sealed.

[0005] Furthermore, Patent Document 3 shows a joined structure in which a first member and a second member made of different materials are arranged separately by a rivet. In this joined structure, in at least one of the first member and the second member, a resin is provided on the surface on the opposite side of the opposing side to prevent moisture from entering, and to prevent the occurrence of rust, corrosion, and electrolytic corrosion.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-267594 [Patent Document 2] Japanese Patent Publication No. 2012-652 [Patent Document 3] Japanese Patent Publication No. 2016-148447 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The technology described in Patent Document 1 above is commonly used for joining dissimilar materials, but self-piercing rivets are a joining method that involves drilling holes and forming the aluminum and steel materials during joining, which requires the application of a large load (several tons). As a result, distortion occurs in the aluminum and steel materials around the joint, and flatness is lost.

[0008] Furthermore, the technology described in Patent Document 2 creates a gap between the light alloy sheet and the steel sheet by spot-welding protrusions, which makes it prone to variations in the size of the gap due to the mechanical properties of the materials and the processing accuracy (protrusion processing). For this reason, stable electrodeposition coating of the gap is difficult.

[0009] The technology described in Patent Document 3 makes it possible to accurately form gaps between members. However, these gaps (separation distances) between members need to be set large in order to allow resin to flow and fill, which causes stress concentration due to moment concentration and leads to a decrease in strength. Therefore, reinforcing members must be placed in the formed gaps between members.

[0010] The present invention solves the above problems and aims to provide a dissimilar material joint, a method for manufacturing a dissimilar material joint, and a stud-equipped aluminum member that can firmly bond dissimilar materials together while ensuring excellent corrosion resistance. [Means for solving the problem]

[0011] This invention consists of the following configuration. (1) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft portion, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The tip of the shaft portion and the steel material are fused together, forming a gap of a desired distance between the aluminum material and the steel material. Joined body of dissimilar materials. (2) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The head and the steel material are fused together, with a gap of a desired interval formed between the aluminum material and the steel material. Joined body of dissimilar materials. (3) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The stud member has a through hole formed in the axial direction of the shaft portion that penetrates the head portion and the shaft portion. The head and the steel material are fused together, with a gap of a desired interval formed between the aluminum material and the steel material. Joined body of dissimilar materials. (4) A studded aluminum member in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A projection is provided on the front surface of the head opposite to the shaft portion, which protrudes in the axial direction of the shaft portion. Aluminum component with studs. (5) A studded aluminum member in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A recess is formed at the tip of the aforementioned shaft portion, which is recessed inward in the axial direction. Aluminum component with studs. (6) A method for manufacturing a dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are joined together, Drive the shaft portion of the stud member having a head portion and a shaft portion into the aluminum material, project the tip of the shaft portion penetrating the aluminum material from the aluminum material, form an enlarged diameter portion that expands radially outward at the tip of the projected shaft portion, and caulking-join the back surface of the head portion facing the aluminum material to the aluminum material. Overlap the tip of the shaft portion and the steel material to form a gap with a desired interval between the aluminum material and the steel material, and fusion-weld the shaft portion and the steel material. Method for manufacturing a dissimilar material joined body. (7) A method for manufacturing a dissimilar material joined body in which a studded aluminum member having a steel stud member attached to an aluminum material and a steel material are joined to each other. Drive the shaft portion of the stud member having a head portion and a shaft portion into the aluminum material, project the tip of the shaft portion penetrating the aluminum material in the plate thickness direction from the aluminum material, form an enlarged diameter portion that expands radially outward at the tip of the projected shaft portion, and caulking-join the back surface of the head portion facing the aluminum material to the aluminum material. Overlap the head portion and the steel material to form a gap with a desired interval between the aluminum material and the steel material, and fusion-weld the head portion and the steel material. Method for manufacturing a dissimilar material joined body.

Effect of the Invention

[0012] According to the present invention, dissimilar materials are firmly joined, and excellent corrosion resistance can be ensured.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a perspective view of a dissimilar material joined body according to a first configuration example. [Figure 2] FIG. 2 is a cross-sectional view perpendicular to the longitudinal direction at the joining portion between the flange portion and the steel material of the dissimilar material joined body according to the first configuration example. [Figure 3]Figure 3 is a longitudinal cross-sectional view of the joint between the flange portion and the steel material of the dissimilar material joint according to the first configuration example. [Figure 4] Figure 4 is a cross-sectional view of the joint between the flange portion of a dissimilar material joint, which has been electrodeposited, and the steel material. [Figure 5] Figure 5 is a cross-sectional view along the direction of the arrangement of stud members, illustrating the crimping process for joining stud members to the flange portion. [Figure 6] Figure 6 is a cross-sectional view of the flange portion to which the stud members are joined, along the direction of the arrangement of the stud members. [Figure 7] Figure 7 is a perspective view of an aluminum extruded material with a stud member crimped to the flange portion. [Figure 8] Figure 8 is a cross-sectional view of a welding area illustrating the spot welding process for welding stud members to steel materials. [Figure 9] Figure 9 is a cross-sectional view of the joint between the flange and the steel material, illustrating another example of the configuration. [Figure 10] Figure 10 is a front view of a dissimilar material joint illustrating another configuration example. [Figure 11] Figure 11 is a cross-sectional view taken perpendicular to the longitudinal direction at the joint between the flange portion and the steel material of the dissimilar material joint according to the second configuration example. [Figure 12] Figure 12 is a longitudinal cross-sectional view of the joint between the flange portion and the steel material of the dissimilar material joint according to the second configuration example. [Figure 13] Figure 13 is a cross-sectional view of a welding area illustrating the spot welding process for welding stud members to steel materials. [Figure 14] Figure 14 is a cross-sectional view of the joint between the flange and the steel material, illustrating another example of the configuration. [Figure 15] Figure 15 is a cross-sectional view of the flange portion at the crimping point of a stud member illustrating another configuration example. [Figure 16] Figure 16 is a cross-sectional view of a welding area illustrating the spot welding process for welding stud members to steel materials. [Figure 17]Figure 17 is a cross-sectional view showing the process of forming an enlarged diameter portion on the shaft of a stud member by a pressing process using a die and a punch. [Figure 18A] Figure 18A is a cross-sectional view of a stud member in which a protruding piece is formed on a part of the tip of a shaft portion having a recessed portion. [Figure 18B] Figure 18B is a plan view of the stud member shown in Figure 18A, viewed from below. [Figure 19A] Figure 19A is a process diagram illustrating the procedure for forming the protruding piece. [Figure 19B] Figure 19B is a process diagram illustrating the procedure for forming the protruding piece. [Figure 19C] Figure 19C is a process diagram illustrating the procedure for forming the protruding piece. [Figure 20] Figure 20 is an explanatory diagram showing the groove structure formed on the upper part of the die shown in Figures 19A to 19C. [Figure 21] Figure 21 is a cross-sectional view showing the process of laser welding a stud member to a steel material. [Figure 22] Figure 22 is a cross-sectional view showing the process of laser welding a stud member having a through hole to a steel material. [Figure 23] Figure 23 is a cross-sectional view showing the electrodeposition coating area when the head of a stud member is joined to a steel material. [Figure 24] Figure 24 is a perspective view of a stud member with projection, seen from the head side. [Figure 25] Figure 25 is a perspective view of the stud member shown in Figure 24, taken from the shaft side. [Figure 26] Figure 26 is a cross-sectional view of the stud member along the line XXVI-XXVI in Figure 24. [Figure 27A] Figure 27A is a cross-sectional view showing the stud member positioned on the embossed surface of the steel plate. [Figure 27B] Figure 27B is a cross-sectional view showing how the stud member is positioned on a projection provided on a steel plate. [Figure 28] Figure 28 is a cross-sectional view of a stud member with a different configuration. [Figure 29A]Figure 29A is a perspective view of a stud member in which a projection is provided in the recess at the tip of the shaft portion, with the projection extending axially. [Figure 29B] Figure 29B is a cross-sectional view of the stud member along the line XXIX-XXIX in Figure 29A. [Figure 30A] Figure 30A is a perspective view of a stud member in which a projection is provided in the recessed portion at the tip of the shaft portion, projecting in the axial direction. [Figure 30B] Figure 30B is a cross-sectional view of the stud member along the line XXX-XXX in Figure 30A. [Figure 31] Figure 31 is a cross-sectional view along the direction of arrangement of the stud members at the joint between the flange portion and the steel material of a dissimilar joint reinforcing member illustrating another configuration example. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. (Example configuration 1) First, we will describe the dissimilar material joint according to the first example configuration. Figure 1 is a perspective view of a dissimilar material joint 100 according to the first configuration example.

[0015] As shown in Figure 1, the dissimilar material joint 100 according to the first configuration example is a dissimilar joint reinforcement member in which a studded aluminum member 150, which has a steel stud member 13 attached to an aluminum extruded material 11, and a steel material 15 are fused together. In other words, the aluminum extruded material 11 and the steel material 15 are joined by the stud member 13. This dissimilar material joint 100 is provided in a vehicle such as an automobile as a structural member called a side sill, and is assembled on both sides of the lower part of the vehicle body along the front-rear direction (direction of travel) of the vehicle.

[0016] The aluminum extruded material 11 is made from a hollow extruded material made of aluminum or an aluminum alloy, having a rectangular hollow cross-section with a thickness (plate thickness) of approximately 2 mm to 5 mm. The aluminum extruded material 11 has a main body portion 21 and a flange portion 23. The main body portion 21 is formed in a hollow cross-sectional shape having two rectangular hollow portions 25. The flange portion 23 is formed in a plate shape and is provided extending along the longitudinal direction of the extruded material, protruding from the outer shape of the main body portion 21. The flange portion 23 protrudes to both sides at one end in a cross-sectional view perpendicular to the longitudinal direction of the main body portion 21. The aluminum extruded material 11 may have a main body portion 21 with one hollow portion 25, or it may have a main body portion 21 with three or more hollow portions 25. The aluminum extruded material 11 may also have one flange portion 23.

[0017] The aluminum alloys used as aluminum extruded materials 11 are those with excellent strength and the ability to be made thinner, such as the 5000 series, 6000 series, and 7000 series aluminum alloys according to JIS or AA standards. These hollow extruded aluminum alloys are manufactured by appropriately combining tempering treatments such as casting (DC casting or continuous casting), homogenization heat treatment, hot extrusion, solution treatment and quenching, and artificial aging treatment as needed. By manufacturing the aluminum extruded materials 11 by extrusion molding of aluminum alloys, weight reduction can be achieved.

[0018] Figure 2 is a cross-sectional view taken perpendicular to the longitudinal direction at the joint between the flange portion 23 and the steel material 15 of the dissimilar material joint 100 according to the first configuration example. Figure 3 is a cross-sectional view taken in the longitudinal direction at the joint between the flange portion 23 and the steel material 15 of the dissimilar material joint 100 according to the first configuration example.

[0019] As shown in Figures 2 and 3, the stud member 13 has a head portion 31 and a shaft portion 33. The head portion 31 is a substantially disc shape with a larger diameter than the shaft portion 33, and the shaft portion 33 is a substantially cylindrical shape that protrudes axially from the center of the head portion 31. The tip of the shaft portion 33 is a flat surface perpendicular to the axial direction.

[0020] The shaft portion 33 of the stud member 13 has an axial length longer than the thickness of the flange portion 23 of the aluminum extruded material 11. This shaft portion 33 penetrates the flange portion 23 in the thickness direction and protrudes from the flange portion 23. The stud member 13 is then riveted and joined to the aluminum extruded material 11 by the plastic flow of aluminum material into the annular groove 34 formed on the back surface 31a of the head portion 31.

[0021] The steel material 15 is, for example, a rolled thin sheet, thick plate, or structural steel, which is commonly used in automobile bodies. In this example, the steel material 15 is a steel plate.

[0022] The steel material 15 is positioned on the protruding side of the stud member 13, which is crimped to the aluminum extruded material 11. The steel material 15 and the tip of the shaft portion 33 of the stud member 13 are then spot-welded. This forms a dissimilar material joint 100 in which the aluminum extruded material 11 and the steel material 15, which are dissimilar metal materials, are joined to each other by the stud member 13. Furthermore, resistance spot welding enables high joint strength to be achieved in a short time, thereby improving productivity.

[0023] In this dissimilar material joint 100, a certain gap G1 is formed between the back surface 31a of the head 31 of the stud member 13 and the steel material 15. This gap G1 is larger than the thickness of the flange portion 23 of the aluminum extruded material 11. Therefore, a certain gap G2 is also formed between the flange portion 23 of the aluminum extruded material 11 and the steel material 15. The dimensions of gaps G1 and G2 are arbitrary and can be controlled to a desired interval. That is, gaps G1 and G2 can be set to a constant dimension regardless of location, and in cases where the steel material 15 has a curved surface, they can be set to a dimension as designed, which varies depending on the location.

[0024] Figure 4 is a cross-sectional view of the joint between the flange portion 23 and the steel member 15 of a dissimilar material joint 100 that has been electrodeposited. As shown in Figure 4, when electrodeposition coating is performed on the dissimilar material joint 100, a coating film C is formed on the outer surface of the aluminum extruded material 11, the outer surface of the steel member 15, and the outer surface of the head 31 of the stud member 13. At this time, a gap G2 is formed between the flange portion 23 of the aluminum extruded material 11 and the steel member 15, so the paint flows smoothly into this gap G2. Therefore, a coating film C is also well formed on the surface of the flange portion 23 that forms this gap G2, the surface of the steel member 15, and the exposed outer surface of the shaft portion 33 of the stud member 13. As the coating film C, a chemical conversion film containing trivalent chromate (trivalent chromium film) is preferred, for example. By using trivalent chromate, cracks are less likely to occur even at high temperatures of 200°C or higher, and a decrease in corrosion resistance can be suppressed.

[0025] In the electrodeposited dissimilar material joint 100, the electrodeposition coating is applied evenly, effectively suppressing corrosion caused by moisture intrusion. The gap G2 between the flange portion 23 of the aluminum extruded material 11 and the steel material 15 is preferably 0.5 mm to 1.5 mm, from the viewpoint of ensuring paint fluidity and the strength of the dissimilar material joint 100.

[0026] Next, a method for manufacturing the dissimilar material joint 100 will be described.

[0027] (Crimping joint process) Figure 5 is a cross-sectional view along the direction of arrangement of the stud members 13 illustrating the crimping process for joining the stud members 13 to the flange portion 23. Figure 6 is a cross-sectional view along the direction of arrangement of the stud members 13 in the flange portion 23 to which the stud members 13 have been joined. Figure 7 is a perspective view of the aluminum extruded material 11 with the stud members 13 crimped to the flange portion 23.

[0028] First, the stud members 13 are crimped and joined to the flange portion 23 of the aluminum extruded material 11. When crimping and joining the stud members 13 to the flange portion 23, it is preferable to crimp multiple stud members 13 to the flange portion 23 simultaneously.

[0029] As shown in Figure 5, a flat die 41 is used to crimp multiple stud members 13 to the flange portion 23 simultaneously. The flat die 41 consists of a female die 43 and a male die 45. The female die 43 is positioned below the male die 45.

[0030] The female mold 43 has multiple holes 47 and its upper surface is formed flat. The flange portion 23 of the aluminum extruded material 11 is positioned on the upper surface of the female mold 43. The male mold 45 has multiple retaining recesses 49 and its lower surface is formed flat. The retaining recesses 49 have a depth approximately the same as the thickness of the head 31 of the stud member 13.

[0031] To crimp and join a stud member 13 to the flange portion 23 of an aluminum extruded material 11 using a flat die 41, first, the flange portion 23 of the aluminum extruded material 11 is placed on the upper surface of the female die 43. Next, the head 31 of the stud member 13 is fitted into the holding recess 49 and pressed with the male die 45 that holds it in place. As a result, the shaft portion 33 of the stud member 13 is driven into the flange portion 23, and the portion of the flange portion 23 corresponding to the shaft portion 33 is punched out by the shaft portion 33 and discharged into the hole 47 of the female die 43. As a result, as shown in Figures 6 and 7, multiple stud members 13 are driven into the flange portion 23 of the aluminum extruded material 11 simultaneously, and a studded aluminum member 150 is obtained in which multiple stud members 13 are crimped to the flange portion 23. The stud member 13 crimped to the flange portion 23 has the tip of its shaft portion 33 protruding through the flange portion 23.

[0032] When the stud members 13 are crimped onto the flange portion 23 using this flat die 41, the flange portion 23 of the aluminum extruded material 11 is compressed by the upper surface of the female die 43 and the lower surface of the male die 45 around the stud member 13 and between adjacent stud members 13. In other words, the surrounding area of ​​the aluminum extruded material 11, including the space between the stud member 13 and other adjacent stud members 13, is compressed by the flat-surfaced dies (female die 43, male die 45). As a result, the flange portion 23 of the aluminum extruded material 11 is restrked (shape corrected by reshaping) to ensure flatness. In addition, the flange portion 23 can be trimmed to a desired shape at the same time as the stud members 13 are pressed in using the flat die 41, in which case weight reduction can be achieved.

[0033] (Spot welding process) Figure 8 is a cross-sectional view of a welding area illustrating the spot welding process for welding the stud member 13 to the steel material 15. As shown in Figure 8, the steel material 15 is placed on the protruding side of the shaft portion 33 of the stud member 13 in the studded aluminum member 150 after the riveting of the stud member 13 has been completed, and the steel material 15 and the flange portion 23 of the aluminum extruded material 11 are overlapped in the thickness direction. Then, the position of the stud member 13 is sandwiched between a pair of welding electrodes 51 and 53, and a welding current is passed through the welding electrodes 51 and 53 while applying pressure with the welding electrodes 51 and 53. In this way, the tip of the shaft portion 33 of the stud member 13 and the steel material 15 are spot welded so that the distance between the back surface 31a of the head 31 of the stud member 13 and the steel material 15 is constant.

[0034] As a result, a nugget (molten portion of resistance spot welding) 30 is formed between the shaft portion 33 and the steel material 15, and the dissimilar metal materials, the aluminum extruded material 11 and the steel material 15, are joined to each other by the stud member 13. This results in a dissimilar material joint 100 in which a certain gap G2 is formed between the flange portion 23 of the aluminum extruded material 11 and the steel material 15. This process involves joining the studded aluminum member 150, in which the aluminum extruded material 11 and the stud member 13 are integrally joined to each other, to the steel material 15. Therefore, the handling of the aluminum extruded material 11 is improved, and the ease of joining with the steel material is enhanced.

[0035] As described above, with the dissimilar material joint 100 of this configuration example, by joining the stud member 13 to the flange portion 23 of the aluminum extruded material 11 by crimping and spot welding it to the steel material 15, a certain gap G2 can be secured between the flange portion 23 and the steel material 15, allowing the electrodeposited coating paint to flow.

[0036] This gap G2 can be precisely maintained between the back surface 31a of the head 31 of the stud member 13 and the steel material 15, so it can be accurately maintained even if there are variations in the thickness of the flange portion 23 of the aluminum extruded material 11. In this way, a constant gap G2 can be accurately maintained between the steel material 15 and the flange portion 23 of the aluminum extruded material 11 during joining, allowing the electrodeposition coating paint to spread evenly. As a result, the intrusion of moisture into the joint after electrodeposition coating is performed can be sufficiently suppressed, and the occurrence of corrosion can be effectively suppressed.

[0037] Furthermore, since the tip of the shaft portion 33 of the stud member 13 is flat, it is possible to suppress the tilting of the stud member 13 when driving it into the flange portion 23 and crimping it.

[0038] Next, we will explain other configuration examples. In the configuration example shown in Figure 9, the steel material 15 has a higher strength than the stud member 13, and the tip of the shaft portion 33 of the stud member 13 has an enlarged diameter bulge portion 33a that bulges out into the gap G2. For example, high-strength steel (high-tensile steel) containing silicon (Si) or manganese (Mn) can be used as the steel material 15.

[0039] To form the enlarged bulge 33a in this configuration example, a steel material 15 having a strength higher than that of the stud member 13 is placed on the protruding side of the shaft portion 33 of the stud member 13, and the shaft portion 33 of the stud member 13 is compressed during spot welding. As a result, the tip portion of the shaft portion 33 of the stud member 13 is softened by the heat around the resistance heating weld (nugget), and expands in diameter and bulges out into the gap G2.

[0040] According to this configuration example, by forming an enlarged diameter bulge 33a at the tip of the stud member 13 in the gap G2, the effect of suppressing detachment when a push-out load is applied is further enhanced.

[0041] In the example configuration shown in Figure 10, the stud members 13 are arranged in a staggered pattern on the flange portion 23 of the aluminum extruded material 11 in a plan view. In other words, the stud members 13 are arranged at different distances L from the edge of the flange portion 23.

[0042] In this configuration example, the points where the studs are driven in are distributed in a direction intersecting the arrangement direction of the stud members 13, which helps to suppress deformation of the flange portion 23 when an external force is applied. Also, since the points where the studs are joined to the steel material 15 are distributed in a direction intersecting the arrangement direction of the stud members 13, the flatness of the flange portion 23 and the steel material 15 is more easily maintained.

[0043] (Second configuration example) Next, we will describe a dissimilar material joint relating to the second example configuration. Note that components identical to those in the first example above are denoted by the same reference numerals and their descriptions are omitted. Figure 11 is a cross-sectional view taken perpendicular to the longitudinal direction at the joint between the flange portion 23 and the steel material 15 of the dissimilar material joint 200 according to the second configuration example. Figure 12 is a cross-sectional view taken longitudinally at the joint between the flange portion 23 and the steel material 15 of the dissimilar material joint 200 according to the second configuration example.

[0044] As shown in Figures 11 and 12, in the dissimilar material joint 200 according to the second configuration example, the stud member 13 is crimped and joined to the flange portion 23 of the aluminum extruded material 11 with the shaft portion 33 penetrating and protruding from the opposite side.

[0045] The steel material 15 is positioned on the head 31 side of the stud member 13, which is crimped and joined to the aluminum extruded material 11. The steel material 15 and the head 31 of the stud member 13 are then butt-welded together. This results in a dissimilar material joint 200 in which the dissimilar metal materials, the aluminum extruded material 11 and the steel material 15, are joined to each other by the stud member 13.

[0046] A smooth and even coating C is formed on the outer surface of the head 31 of the stud member 13, effectively suppressing corrosion caused by moisture intrusion. Furthermore, the gap G3 between the flange portion 23 of the aluminum extruded material 11 and the steel material 15 is preferably 0.5 mm to 1.5 mm, from the viewpoint of ensuring the fluidity of the paint and the strength of the dissimilar material joint 200.

[0047] When manufacturing this dissimilar material joint 200, first, the stud member 13 is crimped and joined to the flange portion 23 of the aluminum extruded material 11 using a flat mold 41 composed of a female mold 43 and a male mold 45 (see Figure 5). At this time, the flange portion 23 of the aluminum extruded material 11 is positioned relative to the female mold 43 in the opposite direction to that used when manufacturing the dissimilar material joint 100.

[0048] Next, as shown in Figure 13, the steel material 15 is placed on the head 31 side of the stud member 13, and the steel material 15 and the flange portion 23 of the aluminum extruded material 11 are overlapped in the thickness direction. Then, the position of the stud member 13 is sandwiched between the pair of welding electrodes 51 and 53, and a welding current is passed through the welding electrodes 51 and 53. This spot welds the head 31 of the stud member 13 and the steel material 15.

[0049] As a result, the aluminum extruded material 11 and the steel material 15, which are dissimilar material joints, are joined to each other by the stud members 13, and a dissimilar material joint 200 is obtained in which a constant gap G3 is formed between the flange portion 23 of the aluminum extruded material 11 and the steel material 15 by the head 31 of the stud members 13. Since the height of the head 31 is generally set to a standard dimension, the gap G3 can be formed with high precision. Furthermore, if it is desired to have different gaps G3 in different locations, a stud member 13 with a head 31 of the corresponding height can be selected.

[0050] As described above, with the dissimilar material joint 200 of this configuration example, by joining the stud member 13 to the flange portion 23 of the aluminum extruded material 11 by crimping and spot welding it to the steel material 15, a certain gap G3 can be secured between the flange portion 23 and the steel material 15, allowing paint to flow.

[0051] This gap G3 can be precisely maintained at a desired distance, such as a certain distance, at the head 31 of the stud member 13, so it can be maintained accurately even if there are variations in the thickness of the flange portion 23 of the aluminum extruded material 11. In this way, the steel material 15 and the flange portion 23 of the aluminum extruded material 11 can be joined while precisely maintaining a gap G3 of the desired interval, so that the paint can be applied evenly. As a result, the intrusion of moisture into the joint can be sufficiently suppressed after electrodeposition coating is performed, and the occurrence of corrosion can be effectively suppressed.

[0052] With this configuration, the gap G3 can be formed with high dimensional accuracy, particularly by the head 31 of the stud member 13.

[0053] In the case of the dissimilar material joint 200 according to this second configuration example, it is also preferable to arrange the stud members 13 in a staggered pattern on the flange portion 23 of the aluminum extruded material 11 in a plan view. By arranging the stud members 13 in a staggered pattern in this way, the points of insertion can be distributed in a direction intersecting the arrangement direction of the stud members 13, thereby suppressing deformation of the flange portion 23 due to external forces. In addition, the points of insertion to the steel material 15 are also distributed in a direction intersecting the arrangement direction of the stud members 13, so that the flatness of the flange portion 23 and the steel material 15 can be maintained.

[0054] <Other configuration examples> Next, we will explain other configuration examples. In the configuration example shown in Figure 14, an enlarged diameter portion 33b is formed at the tip of the shaft portion 33 of the stud member 13A, which widens radially outward. As a result, the flange portion 23 of the aluminum extruded material 11 engages with the enlarged diameter portion 33b of the stud member 13A.

[0055] In this configuration example, since an enlarged diameter portion 33b is formed at the tip of the shaft portion 33 of the stud member 13A, even when a push-out load is applied, the flange portion 23 of the aluminum extruded material 11 engages with the enlarged diameter portion 33b of the stud member 13, thereby enhancing the effect of preventing detachment.

[0056] To form the enlarged diameter portion 33b in this configuration example, it is preferable to use a stud member 13A having a recessed portion 33c formed at the tip of the shaft portion 33 that is recessed inward in the axial direction, as shown in Figure 15. The recessed portion 33c forms a thin-walled annular projection on the outer circumference of the tip of the shaft portion 33. Then, as shown in Figure 16, the position of the stud member 13A is held between a pair of welding electrodes 51, 53, and a welding current is passed through the welding electrodes 51, 53 while applying pressure with the welding electrodes 51, 53. During this spot welding, the annular projection formed by the recessed portion 33c at the tip of the shaft portion 33 of the stud member 13A is expanded by the welding electrode 51 to form the enlarged diameter portion 33b.

[0057] By providing a recessed portion 33c at the tip of the shaft portion 33 of the stud member 13A in this manner, the tip of the stud member 13A can be easily expanded radially outward by the resistance heating and pressure during spot welding. It is preferable to use an electrode with an R-shaped tip as the welding electrode 51 on the tip side of the shaft portion 33, which allows for easy expansion of the outer ring portion of the recessed portion 33c. Furthermore, the recessed portion 33c reduces the weight of the stud member 13A.

[0058] Alternatively, as shown in Figure 17, the enlarged diameter portion 33b may be formed by a pressing process (cold pressing) using a mold 61 and a punch 63. The mold 61 has a recess 61a for accommodating the head 31 of the stud member 13A, and the tip surface 63a of the punch 63 has a curved surface that protrudes axially outward. The stud member 13A has its shaft portion 33 penetrated through the aluminum extruded material 11, and its head portion 31 is placed in the recess 61a of the mold 61. Then, the punch 63 is moved toward the mold 61 by a pressurizing mechanism (not shown), compressing the stud member 13A in the axial direction of the shaft portion 33. As a result, an enlarged diameter portion 33b that bulges radially outward is formed at the tip of the shaft portion 33.

[0059] Furthermore, as shown in Figure 18A, a protruding piece 33d may be formed on a part of the tip of the shaft portion 33 of the stud member 13B having a recessed portion 33c. Figure 18B is a plan view of the stud member 13B shown in Figure 18A, viewed from below. The protruding piece 33d is formed by deforming a part of the annular projection formed by the recessed portion 33c at the tip of the shaft portion 33.

[0060] Figures 19A and 19C are process diagrams illustrating the procedure for forming the protruding piece 33d. As shown in Figure 19A, the aluminum extruded material 11 is placed on the die 65, and a stud member 13B having a recessed portion 33c is pressed against the aluminum extruded material 11 by a pressure mechanism (not shown). Then, as shown in Figure 19B, the shaft portion 33 of the stud member 13B punches out the aluminum extruded material 11. The punched-out blank 67 is discharged through the inner space of the die 65.

[0061] Figure 20 is an explanatory diagram showing the groove structure formed on the upper part of the die 65 shown in Figures 19A to 19C. An opening 71 with an inner diameter slightly larger than the outer circumferential surface of the shaft portion 33 of the stud member 13B is formed on the upper part of the die 65. A convex portion 73 that protrudes radially inward from the inner circumferential surface of the opening and a recess 75 that is formed by recessing radially outward are formed in a part of the opening. The convex portion 73 is also the groove bottom surface of the recess 75, and its radially inward edge 73a is straight. In other words, the convex portion 73 has a straight edge 73a connecting two points on the inner circumferential surface of the opening 71 in the horizontal cross-section of the opening 71, and this edge 73a protrudes radially inward. The recess 75 has an inner wall surface 75a with a curved horizontal cross-section and a bottom surface 75b including the convex portion 73 on the radially outward side of the opening 71. Here, the convex portion 73 and the concave portion 75 are provided at two points that divide the central angle of the opening 71 equally, but they may also be provided at multiple positions that divide the central angle into N equal parts (where N is an integer).

[0062] As shown in Figure 19B, when the blank 67 is punched out, the tip of the shaft portion 33 of the stud member 13 abuts against the protrusion 73. Then, as shown in Figure 19C, when the stud member 13 is further pressed into the aluminum extruded material 11, the back surface 31a of the head 31 is crimped to the aluminum extruded material 11. The thin annular projection formed at the tip of the shaft portion 33 is pressed against the protrusion 73 and deformed, and is pushed out into the recess 75 by plastic flow, forming a protruding piece 33d. As a result, the aluminum extruded material 11 is sandwiched in the thickness direction between the protruding piece 33d, which protrudes radially outward from the shaft portion 33 as shown in Figures 18A and 18B, and the head 31.

[0063] Next, another example of fusion welding for joining the stud member 13 and the steel material 15 will be described. Figure 21 is a cross-sectional view showing the process of laser welding a stud member 13B and a steel material 15. In this case, the steel material 15 is placed on top of the head 31 of the stud member 13B, and laser light LB is irradiated from the side of the steel material 15 opposite to the stud member 13B. The laser light LB is generated by scanning the emitted light from various laser light sources (not shown), such as a CO2 laser, YAG laser, fiber laser, and disk laser, in a circular shape by beam wobbling. This results in a dissimilar material joint 300 in which the steel material 15 and the head 31 of the stud member 13B are joined together by a circular molten and solidified area (laser welding bead) 77. Laser welding makes it easy to achieve a highly flexible joint.

[0064] Figure 22 is a cross-sectional view showing the process of laser welding a stud member 13C having a through hole to a steel material 15. In this case, by using a stud member 13C having a through hole 79 that penetrates in the axial direction, the laser beam LB can be irradiated through the through hole 79 to the joint position between the head 31 and the steel material 15. This also yields a dissimilar material joint 400 in which the steel material 15 and the head 31 of the stud member 13C are joined to each other by a circular molten and solidified portion 77.

[0065] Figure 23 is a cross-sectional view showing the electrodeposited coating area when the head 31 of the stud member 13 is joined to the steel material 15. If the coating C is applied to the entire surface of the stud member 13, the coating formation process can be simplified, but due to the electrical insulation properties of the coating C, it becomes difficult to form a good nugget during resistance spot welding. Therefore, as shown in Figure 23, it is preferable to form the coating C only on the outer circumference of the shaft portion 33, which is the joining interface with the aluminum extruded material 11, and on the back surface 31a of the head 31.

[0066] <Stud component with projection> To ensure conductivity during resistance spot welding while forming a coating over the entire surface of the stud member, it is useful to provide projections. Figure 24 is a perspective view of the stud member 13D having projections 81, viewed from the head side. Figure 25 is a perspective view of the stud member 13D shown in Figure 24, viewed from the shaft side. Figure 26 is a cross-sectional view of the stud member 13D along the line XXVI-XXVI in Figure 24. This stud member 13D has a plurality of projections 81 on the front surface 31b of the head 31, opposite to the shaft 33 side. Through holes 79 are formed in the head 31 and the shaft 33, penetrating in the axial direction. The projections 81 are provided at equal intervals along the circumferential direction of the annular front surface 31b of the head 31, each having a top that has the maximum protruding height.

[0067] The stud member 13D having this projection 81 concentrates the welding current during resistance spot welding, destroying the insulating film at the joint interface with the steel material. As a result, a nugget of good size is formed. Furthermore, although the projection 81 melts and disappears during resistance spot welding, the resulting molten area serves as a starting point for the growth of the nugget in the circumferential and depth directions, thereby reliably increasing the joint strength. In addition, since the projection 81 is evenly distributed in the circumferential direction, circumferential bias of the formed nugget is suppressed. The number of projections 81 is not particularly limited, but three is preferable because it ensures a stable contact position with the mating material.

[0068] In this configuration, the stud member 13D has projections 81 arranged discretely along the circumferential direction on the front surface 31b of the head 31, but they may also be arranged as continuous ring-shaped protrusions along the circumferential direction. In that case, the bonding area with the mating partner can be increased, and a homogeneous nugget can be more easily formed along the circumferential direction.

[0069] As described above, by providing projections 81 on the stud member 13D, the nugget formation position is fixed, improving the stability and robustness of the joint strength. Furthermore, it becomes easier to form large nuggets even with a constant current, enabling a power-saving joint.

[0070] Furthermore, the stud member 13D can be made lighter by having a through hole 79. The through hole 79 can also be used for positioning when joining the stud member 13D. Figure 27A is a cross-sectional view showing the stud member 13D positioned on the emboss 83 of the steel material 15. Figure 27B is a cross-sectional view showing the stud member 13D positioned on a projection 85 provided on the steel material 15.

[0071] As shown in Figure 27A, by forming an emboss 83 on the steel material 15, the through-hole 79 of the stud member 13D can be positioned on the protrusions of the emboss 83. This allows the stud member 13D to be accurately positioned at the location of the emboss 83. Also, as shown in Figure 27B, by providing a projection 85 such as a pin or resin material on the steel material 15, the through-hole 79 of the stud member 13D can be positioned at this projection 85. This allows the stud member 13D to be accurately positioned at the location of the projection 85. As a result, the stud member 13D can be joined to the desired location on the steel material 15 with high positional accuracy.

[0072] Furthermore, the through-hole 79 of the stud member 13B can be used as an insertion point for a probe for non-destructive testing. For example, a probe having a search coil at its tip may be inserted into the through-hole 79 to inspect the quality of the joint between the steel material 15 and the stud member 13B. Alternatively, ultrasonic optical flaw detection may be used to inspect the steel material 15 by applying ultrasonic vibrations and irradiating the surface of the steel material 15 through the through-hole 79 with laser light, detecting voids, bulges, scratches, etc., from the reflected laser light.

[0073] <Examples of other stud member configurations> Figure 28 is a cross-sectional view of a stud member with a different configuration. This stud member 13E has a recessed portion 33c at the tip of the shaft portion 33. The recessed portion 33c has a tapered inner circumferential surface 87 that widens towards the tip of the shaft portion 33. This tapered inner circumferential surface 87 forms an annular projection at the tip of the shaft portion 33 that is thicker at the base end and thinner towards the tip. The other configurations are the same as those of the stud member 13A shown in Figure 15.

[0074] With the stud member 13E of this configuration, when an enlarged diameter portion is formed by expanding the tip of the shaft portion 33 radially outward by resistance spot welding or cold pressing, the volume of the enlarged diameter portion is increased, thereby increasing the engagement strength with the flange portion 23 (Figure 14) of the aluminum extruded material 11. Furthermore, the flare shape of the enlarged diameter portion can be stabilized. In addition, during resistance spot welding, the contact area between the annular projection and the steel material (not shown) to be joined becomes smaller, resulting in the effect of stabilizing the formation position of the nugget.

[0075] Figure 29A is a perspective view of a stud member 13F, which has a projection 89 that protrudes axially from a recessed portion 33c at the tip of a shaft portion 33. Figure 29B is a cross-sectional view of the stud member 13F along the line XXIX-XXIX in Figure 29A. This stud member 13F has the same configuration as the stud member 13E described above, except that a projection 89 is provided in the recessed portion 33c of the stud member 13E, with its tip surface formed of a curved surface (for example, a sphere) having a predetermined radius of curvature. The projection 89 protrudes along the central axis of the shaft portion 33, and its tip is at the same height as, or approximately the same height as, the tip surface 91 on the outer circumference of the shaft portion 33.

[0076] With this configuration of the stud member 13F, a protrusion 89 is formed inside the recess 33c. Therefore, when the tip of the shaft portion 33 is expanded radially outward by resistance spot welding or cold pressing, the volume (thickness, expanded length) of the expanded portion is further increased, thereby improving the engagement strength with the flange portion 23 (Figure 14) of the aluminum extruded material 11. Furthermore, during resistance spot welding, the protrusion 89 comes into contact with the steel material (not shown) to be joined, further stabilizing the position of the stud member 13F. In addition, by providing the protrusion 89, the welding current is concentrated, making it easier to form a large nugget that provides high joint strength.

[0077] Figure 30A is a perspective view of a stud member 13G, which has a projection 93 that protrudes axially from a recessed portion 33c at the tip of a shaft portion 33. Figure 30B is a cross-sectional view of the stud member 13G along the line XXX-XXX in Figure 30A. This stud member 13G has the same configuration as the stud member 13F described above, except that the tip of the projection 89 is made flat. The projection 93 is a frustoconical shape that protrudes along the central axis of the shaft portion 33, and its tip surface is at the same height as, or approximately the same height as, the tip surface 91 of the outer circumference of the shaft portion 33.

[0078] With this configuration of the stud member 13G, a protrusion 93 is formed inside the recess 33c, and as described above, the volume of the enlarged portion, which is formed by expanding the diameter of the tip of the shaft portion 33 radially outward, can be further increased, thereby increasing the engagement strength with the flange portion 23 (Figure 14) of the aluminum extruded material 11. In addition, during resistance spot welding, the protrusion 93 makes surface contact with the steel material (not shown) that will be joined, and during cold pressing, the protrusion 93 makes surface contact with the mold, thus further stabilizing the position of the stud member 13G. Furthermore, by providing the protrusion 93, it becomes easier to form a large nugget that provides high joining strength.

[0079] When joining the various stud members described above to the steel material 15, the orientation of the stud members joined to the steel material 15 may be mixed, with some locations having the shaft portion 33 joined to the steel material 15 and others having the head portion 31 joined to the steel material. Specifically, as shown in Figure 28, the stud members 13 may be driven into the flange portion 23 of the aluminum extruded material 11 in different orientations, and the shaft portion 33 and the steel material 15, and the head portion 31 and the steel material 15 may be spot welded. In this way, it is possible to improve the effect of suppressing push-out by the engagement of the head portion 31 with the flange portion 23, and to ensure a stable gap between the steel material 15 and the flange portion 23 by the head portion 31.

[0080] Thus, the present invention is not limited to the embodiments described above. It is also intended and within the scope of protection to be provided for those skilled in the art to modify and apply the various configurations of the embodiments in combination with each other, based on the description in the specification and well-known art. For example, although aluminum extruded material is given as an example of aluminum material above, the aluminum material is not limited to this, and may also be plate-shaped material made of aluminum sheet, aluminum casting, aluminum wrought material, etc. Furthermore, it is preferable that the enlarged diameter portion 33b (Figure 14), enlarged diameter bulge portion 33a (Figure 9), and protruding piece 33d (Figures 18A, 18B) formed at the tip of the shaft portion of the aforementioned stud member extend to an area that is the same as or exceeds the maximum radial distance of the annular groove 34 (see Figure 28) formed on the back surface of the head portion 31 of the stud member, and extends to an area that is less than or equal to the radial distance of the head portion 31. In addition, the enlarged diameter portion 33b, enlarged diameter bulge portion 33a, and protruding piece 33d extending radially outward may be formed in any form, such as at least one location, multiple locations, or in a continuous annular shape along the circumferential direction of the shaft portion 33.

[0081] As described above, the following matters are disclosed in this specification: (1) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft portion, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The tip of the shaft portion and the steel material are fused together, forming a gap of a desired distance between the aluminum material and the steel material. Joined body of dissimilar materials. This dissimilar material joint allows for a desired gap between the aluminum and steel materials by melt-welding the enlarged diameter portion formed by the shaft of the stud member penetrating the aluminum material to the steel material. The electrodeposition coating paint can then flow into this gap. The desired spacing is maintained by the enlarged diameter portion of the stud member, ensuring accurate gap formation even with variations in the aluminum material's thickness. Thus, the steel and aluminum materials can be joined via the stud member while maintaining a precise gap, allowing the paint to evenly fill the gap. This effectively suppresses moisture intrusion into the joint after electrodeposition coating, effectively preventing corrosion. Furthermore, because the tip of the stud member's shaft is widened by the enlarged diameter portion, the aluminum material engages with the enlarged portion even under a push-out load, enhancing the effect of preventing detachment.

[0082] (2) The dissimilar material joint according to (1), wherein the enlarged diameter portion is a bulge formed by bulging the tip of the shaft portion radially outward. In this dissimilar material joint, the tip of the stud member bulges in the gap between the aluminum and steel materials, causing the aluminum material to be sandwiched between the head of the stud member and the bulging portion. This enhances the effect of suppressing the stud member from coming loose when a push-out load is applied.

[0083] (3) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The head and the steel material are fused together, with a gap of a desired interval formed between the aluminum material and the steel material. Joined body of dissimilar materials. In this dissimilar material joint, the shaft of the stud member penetrates the aluminum material to form an enlarged diameter section, and the head of the stud member is melt-welded to the steel material, thereby securing a desired gap between the aluminum and steel materials. The electrodeposition coating paint can flow into this gap. This gap can be maintained at a desired distance by the enlarged diameter section of the stud member, and the gap can be secured with precision even if there are variations in the thickness of the aluminum material. In this way, the steel material and the aluminum material can be joined via the stud member while maintaining a precise gap, allowing the paint to flow evenly into the gap. As a result, the intrusion of moisture into the joint after electrodeposition coating is performed can be suppressed, effectively inhibiting the occurrence of corrosion. Furthermore, because the tip of the shaft of the stud member is widened by the enlarged diameter section, the aluminum material engages with the enlarged diameter section even when a push-out load is applied, enhancing the effect of preventing detachment.

[0084] (4) A dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The stud member has a through hole formed in the axial direction of the shaft portion that penetrates the head portion and the shaft portion. The head and the steel material are fused together, with a gap of a desired interval formed between the aluminum material and the steel material. Joined body of dissimilar materials. This dissimilar material joint creates through-holes in the stud members, allowing observation of the joint between the stud members and the steel material through these holes. This enables, for example, the insertion of a probe for non-destructive testing into the through-holes or the extraction of reflected light using ultrasonic optical flaw detection, thereby improving the reliability of the inspection.

[0085] (5) The dissimilar material joint according to any one of (1) to (4), wherein a chemical conversion coating is formed on at least the contact surface of the stud member with the aluminum material. This dissimilar material joint allows for the suppression of galvanic corrosion between dissimilar materials through the chemical conversion coating.

[0086] (6) The dissimilar material joint described in (5), wherein the chemical conversion coating includes a trivalent chromium film. This dissimilar material joint makes it less prone to cracking even at high temperatures, thus suppressing the decrease in corrosion resistance.

[0087] (7) The dissimilar material joint according to any one of (1) to (4), wherein the welded portion by fusion welding is a nugget. This dissimilar material joint allows for high joint strength to be achieved in a short time through resistance spot welding.

[0088] (8) The dissimilar material joint according to any one of (1) to (4), wherein the welded portion by fusion welding is an annular bead. This dissimilar material joint allows for easy and highly flexible joining through laser welding.

[0089] (9) The dissimilar material joint according to any one of (1) to (4), wherein the gap is 0.5 mm to 1.5 mm. This dissimilar material joint ensures the fluidity of the paint while also ensuring the strength of the joint.

[0090] (10) The dissimilar material joint according to any one of (1) to (4), wherein the stud members are arranged in a staggered pattern at multiple locations on the aluminum material in a plan view. This dissimilar material joint suppresses deformation of the aluminum material when external forces are applied. Furthermore, since the joint points with the steel material are distributed in a direction intersecting the arrangement direction of the stud members, the flatness of the aluminum and steel materials is more easily maintained.

[0091] (11) The dissimilar material joint according to any one of (1) to (4), wherein the aluminum material is the plate-shaped flange portion of an aluminum extruded material having a main body with a hollow cross-sectional shape and at least one plate-shaped flange portion protruding to the outside of the main body. This dissimilar material joint makes it easy to obtain a reinforcing material by joining steel to an aluminum extruded material.

[0092] (12) A studded aluminum member in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A projection is provided on the front surface of the head opposite to the shaft portion, which protrudes in the axial direction of the shaft portion. Aluminum component with studs. With this studded aluminum member, the stud member is fixed to the aluminum material, improving handling and enhancing the ease of fusion joining with steel material. Furthermore, because the tip of the shaft portion of the stud member is widened by the enlarged diameter portion, even when a push-out load is applied, the aluminum material engages with the enlarged diameter portion of the stud member, increasing the effect of preventing it from coming loose.

[0093] (13) The studded aluminum member according to (12), wherein the projections are provided at least three times on the front surface of the head. This studded aluminum member ensures a stable contact position between the studded member and its mating partner.

[0094] (14) The studded aluminum member according to (12), wherein the projection is provided in an annular manner on the front surface of the head. With this studded aluminum component, homogeneous fusion welding is achieved by the annular projections.

[0095] (15) The stud-equipped aluminum member according to (12), wherein the stud member has a through hole formed in the stud member that penetrates the head and the shaft portion along the axial direction of the shaft portion. With this studded aluminum member, through-holes are formed in the studded member, allowing the joint between the studded member and the steel material to be observed through these through-holes. This allows for, for example, the insertion of a probe for non-destructive testing into the through-hole or the extraction of reflected light using ultrasonic optical flaw detection, thereby improving the reliability of the inspection.

[0096] (16) A studded aluminum member in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A recess is formed at the tip of the aforementioned shaft portion, which is recessed inward in the axial direction. Aluminum component with studs. This studded aluminum component allows for weight reduction of the stud component by forming a recess at the tip of the shaft.

[0097] (17) The studded aluminum member according to (16), wherein the recessed portion has a tapered inner circumferential surface that widens in diameter towards the tip of the shaft portion. With this studded aluminum member, by providing a tapered inner circumferential surface in the recess of the shaft, it is possible to form an annular projection that is thicker at the base end of the shaft tip and thinner towards the tip.

[0098] (18) The studded aluminum member according to (16), wherein a projection is formed at the bottom of the recess, projecting in the axial direction. With this studded aluminum member, by providing a protrusion that extends from the bottom of the recess, when the tip of the shaft is expanded radially outward by resistance spot welding or cold pressing, the volume (thickness, expanded length) of the expanded portion can be further increased, thereby improving the engagement strength with the aluminum material.

[0099] (19) The studded aluminum member according to (18), wherein the tip of the projection is either a flat surface or a curved surface. With this studded aluminum member, if the tip of the protrusion is flat, surface contact occurs between the protrusion and the steel material to be joined during resistance spot welding, and surface contact occurs between the die and the protrusion during cold pressing. Therefore, the position of the studded member can be stabilized. Furthermore, if the tip of the protrusion is curved, the welding current concentrates on the curved tip during resistance spot welding, allowing for the formation of a good nugget.

[0100] (20) The studded aluminum member according to any one of (12) to (19), wherein a chemical conversion coating is formed on at least the contact surface of the stud member with the aluminum material. This studded aluminum component allows for the suppression of galvanic corrosion between dissimilar materials through the chemical conversion coating.

[0101] (21) The studded aluminum member according to (20), wherein the chemical conversion coating includes a trivalent chromium film. This studded aluminum component is less prone to cracking even at high temperatures, thus minimizing the reduction in corrosion resistance.

[0102] (22) A method for manufacturing a dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are joined together, The shaft portion of the stud member having a head and a shaft portion is driven into the aluminum material, the tip of the shaft portion that has penetrated the aluminum material protrudes from the aluminum material, an enlarged diameter portion that widens radially outward is formed at the tip of the protruding shaft portion, and the back surface of the head portion facing the aluminum material is riveted and joined to the aluminum material. The tip of the shaft portion and the steel material are overlapped, and a gap of a desired distance is formed between the aluminum material and the steel material, while the shaft portion and the steel material are fused and welded together. A method for manufacturing a joint of dissimilar materials. According to this method for manufacturing dissimilar material joints, a stud member is crimped to an aluminum material, and the stud member and the steel material are fused together, thereby securing a desired gap between the aluminum and steel materials. Electrodeposition coating paint can then flow into this gap. The desired spacing can be maintained by the enlarged diameter portion of the stud member, ensuring accurate gap formation even if there are variations in the thickness of the aluminum material. In this way, the steel and aluminum materials can be joined via the stud member while maintaining a precise gap, allowing the paint to evenly fill the gap. This effectively suppresses moisture intrusion into the joint after electrodeposition coating, effectively preventing corrosion. Furthermore, because the tip of the stud member's shaft is widened by the enlarged diameter portion, the aluminum material engages with the enlarged portion even under a push-out load, enhancing the effect of preventing detachment.

[0103] (23) Using the steel material having higher strength than the stud member, A method for manufacturing a dissimilar material joint according to (22), wherein the tip of the shaft portion of the stud member is pressed against the steel material and resistance spot welded to compress the shaft portion in the axial direction, thereby forming an enlarged diameter bulge at the tip of the shaft portion that bulges radially outward. According to this method for manufacturing dissimilar material joints, an enlarged bulge can be formed in the gap between the aluminum material and the steel material, thereby enhancing the effect of suppressing detachment when a push-out load is applied.

[0104] (24) A method for manufacturing a dissimilar material joint in which a studded aluminum member, which has a steel stud member attached to an aluminum material, and a steel material are joined together, The shaft portion of the stud member having a head and a shaft portion is driven into the aluminum material, the tip of the shaft portion that penetrates the aluminum material in the thickness direction is made to protrude from the aluminum material, an enlarged diameter portion that widens radially outward is formed at the tip of the protruding shaft portion, and the back surface of the head portion facing the aluminum material is riveted and joined to the aluminum material. The head and the steel material are overlapped, and the head and the steel material are fused together while forming a gap of a desired interval between the aluminum material and the steel material. A method for manufacturing a joint of dissimilar materials. According to this method for manufacturing dissimilar material joints, a stud member is crimped to an aluminum material, and the stud member and the steel material are fused together, thereby securing a desired gap between the aluminum and steel materials. Electrodeposition coating paint can then flow into this gap. The desired spacing can be maintained by the enlarged diameter portion of the stud member, ensuring accurate gap formation even if there are variations in the thickness of the aluminum material. In this way, the steel and aluminum materials can be joined via the stud member while maintaining a precise gap, allowing the paint to evenly fill the gap. This effectively suppresses moisture intrusion into the joint after electrodeposition coating, effectively preventing corrosion. Furthermore, because the tip of the stud member's shaft is widened by the enlarged diameter portion, the aluminum material engages with the enlarged portion even under a push-out load, enhancing the effect of preventing detachment.

[0105] (25) The method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein the fusion welding is resistance spot welding. This method for manufacturing dissimilar material joints allows for high joint strength to be achieved in a short time through resistance spot welding.

[0106] (26) The method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein the fusion welding is laser welding. According to this method for manufacturing dissimilar material joints, a highly flexible joining process can be easily achieved by laser welding.

[0107] (27) A method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein the stud member is compressed in the axial direction of the shaft portion at the same time as the fusion welding, causing the tip of the shaft portion of the stud member to bulge into the gap. According to this method for manufacturing dissimilar material joints, the tip of the stud member bulges in the gap between the aluminum and steel materials, causing the aluminum material to be sandwiched between the head and bulging portion of the stud member. This enhances the effect of suppressing the stud member from coming loose when a push-out load is applied.

[0108] (28) Using the stud member in which an annular thin-walled portion is formed along the outer surface of the shaft portion at the tip of the shaft portion, A method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein the shaft portion is passed through the aluminum material, and then the tip of the shaft portion is compressed in the axial direction to expand the diameter of the annular thin-walled portion. According to this method for manufacturing dissimilar material joints, by expanding the tip of the shaft portion of the stud member radially outward, the aluminum material engages with the expanded portion of the stud member even when a push-out load is applied, thereby enhancing the effect of preventing detachment.

[0109] (29) Using the stud member in which an annular thin-walled portion is formed along the outer surface at the tip of the shaft portion, A method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein the shaft portion is passed through the aluminum material, the head portion and the steel material are overlapped, and the tip of the shaft portion and the steel material are spot welded by sandwiching them with a pair of spot welding electrodes. According to this method for manufacturing dissimilar material joints, the tip of the stud member can be easily expanded in diameter by the resistance heating and pressurization during spot welding.

[0110] (30) The process includes simultaneously driving multiple stud members into the aluminum material, The method for manufacturing a dissimilar material joint according to any one of (22) to (24), wherein in the step described above, the surrounding region of the aluminum material, including the space between the stud member and other stud members adjacent to it, is compressed by a die with a flat press surface. According to this method for manufacturing dissimilar material joints, when the stud member is driven in, the area surrounding the stud member in the aluminum material is compressed and restrked by a mold. This ensures the flatness of the flange portion. [Explanation of Symbols]

[0111] 11. Aluminum extruded material (aluminum material) 13, 13A, 13B, 13C, 13D, 13E, 13F, 13G Stud members 15 Steel 21 Main body 23 Flange section 25 Hollow part 30 Nugget (molten part of resistance spot welding) 31 Head 31a Back side 31b Front side 33 Shaft section 33a Expanded diameter bulge 33b Expanded diameter part 33c recessed area 33d protruding piece 34 Ring groove 41 Flat mold 43 Female type 45 Male type 47 Hole 49 Retaining recess 51, 53 Welding electrodes 61 molds 61a Recess 63 Punch 63a Tip surface 65 dice 67 Blank 69 Interior space 71 Aperture 73 Convex part 73a Edge 75 recess 75a Inner wall surface 75b Base 77. Molten and solidified area (bead of laser welding) 79 Through hole 81 Projection 83 Embossed 85 Protrusion 87 Inner surface 89 Protrusion 91 Tip surface 93 Protrusion 100,200,300,400 Different materials joined body 150 Studded Aluminum Components C Coating film G1, G2, G3 gaps LB laser light

Claims

1. A dissimilar material joint in which a studded aluminum member, which has steel stud members attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft portion, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The stud member has a through hole formed in the axial direction of the shaft portion that penetrates the head portion and the shaft portion. The tip of the shaft portion and the steel material are fused together, forming a gap of a desired distance between the aluminum material and the steel material. Joined body of dissimilar materials.

2. The enlarged diameter portion is a bulge formed by extending the tip of the shaft portion radially outward. The dissimilar material joint described in claim 1.

3. A dissimilar material joint in which a studded aluminum member, which has steel stud members attached to an aluminum material, and a steel material are fused together, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The stud member has a through hole formed in the axial direction of the shaft portion that penetrates the head portion and the shaft portion. The head and the steel material are fused together, with a gap of a desired interval formed between the aluminum material and the steel material. Joined body of dissimilar materials.

4. The dissimilar material joint according to any one of claims 1 to 3, wherein a chemical conversion coating is formed on at least the contact surface of the stud member with the aluminum material.

5. The dissimilar material joint according to claim 4, wherein the aforementioned chemical conversion coating includes a trivalent chromium film.

6. The welded portion formed by the aforementioned fusion welding is a nugget. A dissimilar material joint according to any one of claims 1 to 3.

7. The welded portion formed by the aforementioned fusion welding is an annular bead. A dissimilar material joint according to any one of claims 1 to 3.

8. The gap is 0.5 mm to 1.5 mm. A dissimilar material joint according to any one of claims 1 to 3.

9. The stud members are arranged in a staggered pattern at multiple locations on the aluminum material in a plan view. A dissimilar material joint according to any one of claims 1 to 3.

10. The dissimilar material joint according to any one of claims 1 to 3, wherein the aluminum material is the plate-shaped flange portion of an aluminum extruded material having a main body portion with a hollow cross-sectional shape and at least one plate-shaped flange portion protruding to the outside of the main body portion.

11. A studded aluminum member is formed in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material. The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A projection is provided on the front surface of the head opposite to the shaft portion, projecting in the axial direction of the shaft portion. The stud member has a through hole formed in the axial direction of the shaft portion, which penetrates the head portion and the shaft portion. Aluminum component with studs.

12. The aforementioned protrusions are provided at least three times on the front surface of the head. The aluminum member with studs according to claim 11.

13. The aforementioned projection is provided in an annular shape on the front surface of the head. The aluminum member with studs according to claim 11.

14. A studded aluminum member in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material, The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, and an enlarged diameter portion is formed at the tip of the protruding shaft portion, which widens radially outward. The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The stud member has a through hole formed in the axial direction of the shaft portion, which penetrates the head portion and the shaft portion. Aluminum component with studs.

15. A studded aluminum member is formed in which a steel stud member is attached to an aluminum material, and the stud member is fused-welded to the steel material. The stud member has a head and a shaft, The shaft portion penetrates the aluminum material in the thickness direction and protrudes from the aluminum material, The back surface of the head facing the aluminum material is riveted and joined to the aluminum material. A recess is formed at the tip of the aforementioned shaft portion, which is recessed inward in the axial direction. Aluminum component with studs.

16. The recessed portion has a tapered inner circumferential surface that widens in diameter towards the tip of the shaft portion. The studded aluminum member according to claim 15.

17. A projection is formed at the bottom of the recessed portion, projecting in the axial direction. The studded aluminum member according to claim 15.

18. The tip of the aforementioned projection is either a flat surface or a curved surface. The studded aluminum member according to claim 17.

19. The studded aluminum member according to any one of claims 11 to 18, wherein a chemical conversion coating is formed on at least the contact surface of the stud member with the aluminum material.

20. The aluminum member with studs according to claim 19, wherein the chemical conversion coating includes a trivalent chromium film.

21. A method for manufacturing a dissimilar material joint in which a studded aluminum member, which has steel stud members attached to an aluminum material, and a steel material are joined together, The shaft portion of the stud member having a head and a shaft portion is driven into the aluminum material, the tip of the shaft portion that has penetrated the aluminum material protrudes from the aluminum material, an enlarged diameter portion that widens radially outward is formed at the tip of the protruding shaft portion, and the back surface of the head portion facing the aluminum material is riveted and joined to the aluminum material. The tip of the shaft portion and the steel material are overlapped, and a gap of a desired distance is formed between the aluminum material and the steel material, while the shaft portion and the steel material are fused and welded together. A method for manufacturing a joint of dissimilar materials.

22. Using the steel material having higher strength than the stud member, The tip of the shaft portion of the stud member is pressed against the steel material and resistance spot welded to compress the shaft portion in the axial direction, thereby forming an enlarged diameter bulge at the tip of the shaft portion that bulges radially outward. A method for manufacturing a dissimilar material joint according to claim 21.

23. A method for manufacturing a dissimilar material joint in which a studded aluminum member, which has steel stud members attached to an aluminum material, and a steel material are joined together, The stud member has a head and a shaft, and a through hole is formed through the head and the shaft along the axial direction of the shaft. The shaft of the stud member is driven into the aluminum material, the tip of the shaft that penetrates the aluminum material in the thickness direction protrudes from the aluminum material, an enlarged diameter portion is formed at the tip of the protruding shaft that widens radially outward, and the back surface of the head facing the aluminum material is riveted and joined to the aluminum material. The head and the steel material are overlapped, and the head and the steel material are fused together while forming a gap of a desired interval between the aluminum material and the steel material. A method for manufacturing a joint of dissimilar materials.

24. The method for manufacturing a dissimilar material joint according to any one of claims 21 to 23, wherein the fusion welding is resistance spot welding.

25. The method for manufacturing a dissimilar material joint according to any one of claims 21 to 23, wherein the fusion welding is laser welding.

26. Simultaneously with the fusion welding, the stud member is compressed in the axial direction of the shaft portion, causing the tip of the shaft portion of the stud member to bulge radially outward. A method for manufacturing a dissimilar material joint according to any one of claims 21 to 23.

27. Using the stud member in which an annular thin-walled portion is formed along the outer surface of the shaft portion at the tip of the shaft portion, After the shaft portion is passed through the aluminum material, the tip of the shaft portion is compressed in the axial direction to expand the diameter of the annular thin-walled portion. A method for manufacturing a dissimilar material joint according to any one of claims 21 to 23.

28. Using the stud member in which an annular thin-walled portion is formed along the outer surface at the tip of the shaft portion, After the shaft portion is passed through the aluminum material, the head portion and the steel material are overlapped, and the tip of the shaft portion and the steel material are clamped together with a pair of spot welding electrodes and spot welded. A method for manufacturing a dissimilar material joint according to any one of claims 21 to 23.

29. The process includes simultaneously driving multiple stud members into the aluminum material, In the above step, the surrounding region of the aluminum material, including the space between the stud member and other stud members adjacent to it, is compressed by a die with a flat press surface. A method for manufacturing a dissimilar material joint according to any one of claims 21 to 23.

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