JP5938747B2 - Rivet, dissimilar material joining structure provided with rivets, and dissimilar material joint manufacturing method - Google Patents

Description

  The present invention relates to a rivet for joining a first member and a second member made of metal materials different from each other, a dissimilar material joining structure provided with a rivet, and a method for producing a dissimilar material joined body.

  When the first member and the second member made of different metal materials are joined by welding, a highly brittle intermetallic compound (for example, the first member is made of an aluminum alloy and the second member is made of steel at the interface between them. In this case, an Al—Fe-based intermetallic compound) is generated, which may cause a problem that bonding strength is reduced. Typical welding techniques include resistance welding spot welding, fusion welding MIG welding and laser welding. In fusion welding, there is a problem that the members to be joined are deformed due to thermal distortion because the amount of heat input is large.

  Therefore, in order to solve the above two problems, Patent Documents 1 and 2 disclose that a rivet is composed of the same metal material as that of the metal material constituting the second member and is caulked and fastened to the first member. A method is disclosed in which the first member and the second member are joined by spot-welding the second member to the second member. That is, the dissimilar material joining structure in which a rivet is caulked and fastened to the first member and the second member are arranged so as to overlap each other, and the rivet head and the second member are sandwiched between a pair of resistance spot welding electrodes. The tip of the shaft portion and the second member are spot welded. Thereby, the dissimilar-material joined body with which the 1st member and the 2nd member were joined via the rivet is manufactured.

JP 2009-285678 A JP 2010-207898 A

  In the process of manufacturing the dissimilar material joined body disclosed in Patent Documents 1 and 2 described above, when spot welding is performed due to variations in the assembly accuracy of the dissimilar material joining structure, the electrode relative to the center position of the rivet is used. The position may shift. When the electrode position is shifted as described above, a high-temperature molten nugget generated at the welded portion between the tip of the shaft portion of the rivet and the second member is formed away from the center position of the rivet, that is, near the first member. Is done. Therefore, the first member is softened by the heat of the molten nugget, and the joint strength is reduced.

  Accordingly, an object of the present invention is to provide a rivet capable of performing dissimilar material joining while suppressing the formation of intermetallic compounds and softening of the first member, a dissimilar material joining structure provided with a rivet, and a method for producing a dissimilar material joined body. It is to provide.

A rivet according to the first invention is a joint formed by overlapping a first member made of a metal material and a second member made of a metal material having a melting point higher than that of the metal material making up the first member. A rivet for fastening
The rivet is made of a metal material having the same main component as the second member,
The rivet has a plate-like head that is caulked and fastened to the first member, and a shaft portion that extends from the head and penetrates the first member and has a tip that is spot welded to the second member. And
The plate-like head and the shaft tip are respectively provided with a head raised portion and a shaft tip raised portion,
The orthographic projection surfaces of the head raised portion and the axial tip raised portion as viewed from the axial direction of the shaft portion overlap each other at the center of the orthographic projection surface of the shaft portion, and both are entirely the shaft portion. It is located in the orthographic projection plane.

  In addition, the “head raised portion” means a portion that is raised above the edge of the head on the side opposite to the shaft portion side in the head, and that is in contact with the electrode during spot welding. In addition, the “shaft tip raised portion” means a portion that is raised from the edge of the shaft tip at the tip of the shaft, and that is in contact with the second member during spot welding.

  Since this rivet is made of the same metal material as the main component of the metal material constituting the second member, it is caulked and fastened to the first member and its tip is spot welded to the second member. Dissimilar material joining can be performed while suppressing generation of a compound. Moreover, when performing spot welding, the electrode arrange | positioned at the rivet side contacts the head protruding part formed in the head. And a fusion nugget is formed between the shaft tip protuberance formed on the shaft portion of the rivet and the second member. Here, the orthographic projection surfaces of the head raised portion and the axial tip raised portion as viewed from the axial direction of the shaft portion overlap each other at the center of the orthographic projection surface of the shaft portion, and all of the normal projection surfaces of the shaft portion are normal. Since it is located in the projection plane, even when the electrode position is deviated from the center position of the rivet, the molten nugget can be hardly formed in the vicinity of the first member. Therefore, it is possible to suppress the first member from being softened by the heat of the molten nugget.

  The rivet according to the second invention is the rivet according to the first invention, wherein the head raised portion, the shaft tip raised portion, and the shaft portion are all coaxially positioned.

  If the center of the head ridge is displaced from the center axis of the rivet, the electrode contacts the head ridge when the electrode is displaced in the direction opposite to the direction of displacement of the head ridge relative to the radial direction of the rivet. Without touching the portion where the head bulge is not formed. Further, when the center of the shaft tip raised portion is deviated from the center axis of the rivet, when the electrode is displaced in the same direction as the direction of displacement of the shaft tip raised portion with respect to the radial direction of the rivet, Molten nuggets may form. In the rivet described above, it is possible to make it difficult for the electrode to come off from the raised portion of the head, and to reliably suppress the formation of the molten nugget near the first member.

  The rivet according to a third aspect of the present invention is the rivet according to the first or second aspect of the present invention, wherein the whole orthographic projection surface of the shaft tip bulge portion viewed from the axial direction of the shaft portion is the normal ridge of the head bulge portion. Located in the projection plane.

  In this rivet, since the shaft tip raised portion is relatively small, it is possible to suppress the molten nugget generated between the shaft tip raised portion and the second member from greatly deviating from the center of the rivet. Therefore, it can suppress reliably that a 1st member softens with the heat | fever of a fusion | melting nugget.

  A rivet according to a fourth aspect of the present invention is the rivet according to any one of the first to third aspects, wherein the rivet is a portion excluding the head raised portion and the shaft tip raised portion, and at least a portion in contact with the first member. In addition, a first insulating film is formed.

  In the case of providing a plurality of rivets, when spot-welding one rivet to the second member and then spot-welding the rivet disposed adjacent to the second member to the second member, the welding current is directed toward the rivet that has already been welded. So-called diversion is likely to occur. Therefore, welding is not performed appropriately, and the bonding strength of the rivet to the second member can be reduced. On the other hand, in the rivet configured as described above, the presence of the first insulating film prevents the welding current from flowing toward the already welded rivet. Thereby, said problem can be reduced. Moreover, the electrolytic corrosion which arises between a rivet and the 1st member can be prevented.

  A rivet according to a fifth invention is a joint formed by stacking a first member made of a metal material and a second member made of a metal material having a melting point higher than that of the metal material making up the first member. The rivet is made of the same metal material as that of the first member, and the rivet extends from the head by a plate-like head that is caulked and fastened to the first member. A shaft portion that penetrates the first member and the tip of which is spot-welded to the second member, and a head electrical conduction portion on the plate surface of the head portion and a shaft tip electrical connection at the tip of the shaft portion. The portion excluding the conducting portion is covered with the first insulating film, and the orthographic projection surface of the head conducting portion and the shaft tip electrical conducting portion viewed from the axial direction of the shaft portion is the orthographic projection surface of the shaft portion. Are overlapped with each other at the center of the shaft. A rivet located within the projection surface.

  In this rivet, similarly to the first invention, it is possible to perform dissimilar material joining while suppressing generation of intermetallic compounds and softening of the first member.

  A rivet according to a sixth invention is the rivet according to the fifth invention, wherein the head electrical conduction part, the shaft tip electrical conduction part, and the shaft part are all coaxially positioned.

  In this rivet, similarly to the second invention, it is possible to make it difficult for the electrode to be detached from the head electrical conduction portion, and to reliably suppress the formation of the molten nugget in the vicinity of the first member.

  A rivet according to a seventh aspect of the present invention is the rivet according to the fifth or sixth aspect, wherein the whole orthographic projection surface of the shaft tip electrical conduction part viewed from the axial direction of the shaft part is the head electrical conduction part. It is located in the orthographic projection plane.

  In this rivet, similarly to the rivet according to the third invention, it is possible to suppress the molten nugget from largely deviating from the center of the rivet and to surely suppress the softening of the first member.

  A rivet according to an eighth invention is the rivet according to any one of the first to seventh inventions, wherein a groove is formed around the shaft portion on the surface of the head facing the first member.

  In this rivet, since the first member enters the groove of the rivet when the rivet is caulked and fastened to the first member, the fastening force of the rivet to the first member can be further increased.

  In the dissimilar material bonding structure according to the ninth aspect, the rivet according to any one of the first to eighth aspects is caulked and fastened.

  This dissimilar material bonding structure can perform dissimilar material bonding while suppressing generation of intermetallic compounds and softening of the first member, as in the first and fifth inventions. In addition, by manufacturing the dissimilar material joining structure by caulking and fastening the rivet to the first member in advance, the rivet is not detached from the first member in handling until the second member is welded.

  A manufacturing method for a dissimilar material joint according to a tenth aspect of the present invention is a method for manufacturing a dissimilar material joining structure in which a rivet according to any one of the first to eighth aspects is caulked and fastened to the first member to manufacture a dissimilar material joining structure. A stacking step of stacking and arranging the second member on the tip side of the shaft portion of the rivet in the first member of the dissimilar material bonding structure, the head portion of the rivet, and the second member Is sandwiched between a pair of resistance spot welding electrodes, and a welding step of spot welding the tip of the shaft portion of the rivet and the second member is provided.

  In this method for producing a dissimilar material joined body, dissimilar material joining can be performed while suppressing generation of intermetallic compounds and softening of the first member, as in the first, fifth, and ninth inventions.

  The manufacturing method of the dissimilar material assembly according to the eleventh aspect of the present invention is the manufacturing method of the dissimilar material assembly according to the tenth aspect of the present invention, in both of the first member and the second member before the laminating step. The method further includes an insulating film forming step of forming a second insulating film in the overlapping portion.

  In this method of manufacturing the dissimilar material joined body, electrolytic corrosion that occurs between the first member and the second member can be prevented.

  The dissimilar material joining can be performed while suppressing the generation of the intermetallic compound and the softening of the first member.

It is a perspective view of the rivet concerning 1st Embodiment of this invention, (a) is what was seen from the head side, (b) was seen from the axial part side. It is the top view seen from the head side regarding the axial direction of the rivet shown in FIG. It is sectional drawing which follows the axial direction of the rivet shown in FIG. It is a fragmentary sectional view which shows the structure for different material joining which crimped and fastened the rivet shown in FIG. 1 to the 1st member. It is a figure which shows the process in which the dissimilar-material joining structure shown in FIG. 4 is joined to a 2nd member, and manufactures a dissimilar-material joined body, (a) is an insulation film formation process, (b) is a dissimilar-material joining structure manufacturing process. (B) shows a lamination process, (c) shows a welding process, and (d) shows a completed dissimilar material joined body. FIG. 5 (d) shows a path of a welding current flowing in the rivet in the welding process shown in FIG. 5 (d), where (a) shows the center of the electrode coincides with the center of the rivet, and (b) shows the center of the electrode. The case where it deviates from the center of a rivet is shown. It is sectional drawing which follows the axial direction of the rivet concerning 2nd Embodiment of this invention. It is sectional drawing which shows the modification of the rivet of 1st Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described.

  The rivet 1 according to the first embodiment of the present invention joins a first member 3 and a second member 5 made of different metal materials to form a dissimilar material joined body 10 (see FIG. 5E). Is to do. The second member 5 is made of a metal material having a melting point higher than that of the first member 3. The rivet 1 is made of a metal material having the same base component as that of the metal material constituting the second member 5. In the present embodiment, the first member 3 is made of an aluminum alloy, and the rivet 1 and the second member 5 are made of steel. The melting point (for example, approximately 1400 to 1600 ° C.) of the steel constituting the rivet 1 and the second member 5 is higher than the melting point (for example, approximately 660 ° C.) of the aluminum alloy constituting the first member 3.

  The rivet 1 is formed by, for example, machining such as cutting and grinding, or forging. From the viewpoint of rivet productivity, rivet strength, and dimensional accuracy of the head and the shaft tip bulge, the rivet 1 is forged. It is preferable to be molded. As shown in FIGS. 1 and 2, the rivet 1 includes a disc-shaped head portion 11 having a diameter dH and a substantially cylindrical shaft portion 13 having a diameter dS extending from a central portion of one surface of the head portion 11. Have. In the following description, with respect to the axial direction of the shaft portion 13 (hereinafter, simply referred to as “axial direction”), the head portion 11 side is defined as the upper side, and the tip end side of the shaft portion 13 is defined as the lower side.

  A head raised portion 11a having a circular shape with a diameter dP1 in a top view is formed at the center of the head 11 on the surface (upper surface) opposite to the side on which the shaft portion 13 is provided. Further, a shaft tip raised portion 13a having a circular shape with a diameter dP2 when viewed from the bottom is formed at the center of the tip of the shaft portion 13. As shown in FIG. 3, the cross-sections of the head raised portion 11a and the shaft tip raised portion 13a are both rectangular in the direction orthogonal to the axial direction. The center O2 of the head raised portion 11a and the center O3 of the shaft tip raised portion 13a are both located on the axis O1, which is the central axis of the shaft portion 13. Further, a groove 11 b is formed on the bottom surface of the head 11. The groove 11 b is formed in an annular shape around the shaft portion 13.

  As shown in FIG. 2, the entire orthographic projection surface of the head raised portion 11 a viewed from the axial direction is located within the orthographic projection surface of the axial portion 13. Further, the entire orthographic projection surface of the shaft tip bulging portion 13a is located within the orthographic projection surface of the head bulging portion 11a. That is, the orthographic projection surfaces of the head raised portion 11 a and the shaft tip raised portion 13 a are all located within the orthographic projection surface of the shaft portion 13. The diameter dS of the shaft portion 13> the diameter dP1 of the head raised portion> the diameter dP2 of the shaft tip raised portion.

  An insulating coating 15 is formed on the surface of the rivet 1 excluding the head raised portion 11a and the shaft tip raised portion 13a. The insulating coating 15 is formed of, for example, DISGO (registered trademark), Raffle (registered trademark), Geomet (registered trademark), polyester resin precoat, silicone elastomer, or the like.

  As shown in FIG. 4, the dissimilar material joining structure 20 is formed by piercing and caulking the rivet 1 as described above to the plate-like first member 3 by press working. More specifically, in the rivet 1, the head portion 11 is disposed on the front surface 3a of the first member 3, and the shaft portion 13 extends from the front surface 3a to the back surface 3b (the surface opposite to the front surface 3a). The member 3 is penetrated. That is, the tip of the shaft portion 13 of the rivet 1 is located on the back surface 3 b side of the first member 3. The rivet 1 enters the groove 11 b formed in the bottom surface of the head 11 in the rivet 1 by plastic flow around the shaft portion 13 in the first member 3, so that the rivet 1 is not pulled out from the first member 3. It is firmly crimped.

  Next, a method for manufacturing the dissimilar material bonded body 10 will be described.

  As shown in FIG. 5A, first, an insulating coating 5a is formed on the surface (upper surface in the drawing) of the plate-like second member 5 with a sealer, an adhesive, an adhesive tape or the like (insulating coating forming step). Subsequently, the rivet 1 is caulked and fastened to the plate-like first member 3 to manufacture the dissimilar material bonding structure 20 as shown in FIG. 5B (dissimilar material bonding structure manufacturing process). Further, the second member 5 on which the insulating coating 5a is formed in the insulating coating forming step is disposed so as to overlap with the dissimilar material bonding structure 20 manufactured in the dissimilar material bonding structure manufacturing step (stacking step). That is, as shown in FIG. 5 (c), the second member 5 is arranged such that the surface of the second member 5 on which the insulating coating 5 a is formed faces the back surface 3 b of the first member 3 of the dissimilar material bonding structure 20. Place. At this time, the shaft tip raised portion 13 a formed at the tip of the shaft portion 13 of the rivet 1 comes into contact with the second member 5.

  Then, as shown in FIG. 5 (d), the head 11 of the rivet 1 and the second member 5 are sandwiched between a pair of resistance spot welding electrodes 51 and 52. At this time, the resistance spot welding electrode 51 on the rivet 1 side comes into contact with the head raised portion 11 a formed on the head 11. And the front-end | tip of the axial part 13 of the rivet 1 and the 2nd member 5 are spot-welded (welding process). Thereby, the 2nd member 5 is joined with the 1st member 3 via the rivet 1, and the dissimilar-materials joined body 10 as shown in FIG.5 (e) is completed. In the dissimilar material joined body 10, a melt nugget 55 is formed at a spot welded portion between the shaft tip raised portion 13 a of the shaft portion 13 of the rivet 1 and the second member 5.

  Here, the path of the welding current flowing in the rivet 1 in the welding process will be described. First, as shown in FIG. 6A, when the center position of the rivet 1 (position of the axis O1) and the center position of the resistance spot welding electrodes 51 and 52 (position of the axis O4) coincide, Flows through the center of the rivet 1 along the axis O1. At this time, the molten nugget 55 is formed at the center of the shaft tip raised portion 13a. On the other hand, as shown in FIG. 6B, when the center position (position of the axis O4) of the resistance spot welding electrodes 51 and 52 is deviated from the center position of the rivet 1 (position of the axis O1), The resistance spot welding electrode 51 on the rivet 1 side comes into contact with a part of the head raised portion 11a. That is, no current flows outside the head raised portion 11a. Further, the shaft tip raised portion 13a is located on the axis O1, and the entire orthographic projection surface viewed from the axial direction is located within the orthographic projection surface of the head raised portion 11a. The electric current flowing through the inside flows from the head raised portion 11a toward the shaft tip raised portion 13a so as to approach the axis O1.

  As described above, according to the manufacturing method of the rivet 1, the dissimilar material bonding structure 20, and the dissimilar material bonded body 10 according to the present embodiment, the metal material and the base component constituting the second member 5 are the same. The rivet 1 made of a metal material is caulked and fastened to the first member 3 and the tip of the rivet 1 is spot welded to the second member 5, thereby making it possible to perform dissimilar material joining while suppressing generation of intermetallic compounds. Further, when spot welding is performed, the resistance spot welding electrode 51 disposed on the rivet 1 side comes into contact with the head raised portion 11 a formed on the head 11. Then, a molten nugget is formed between the shaft tip raised portion 13 a formed on the shaft portion 13 of the rivet 1 and the second member 5. Here, the orthographic projection surfaces of the head raised portion 11a and the axial tip raised portion 13a viewed from the axial direction of the shaft portion 13 overlap with each other at the center of the orthographic projection surface of the shaft portion 13, and both are entirely Since it is located in the orthographic projection plane of the shaft portion 13, even when the center positions of the electrodes 51 and 52 are deviated from the center position of the rivet 1, the molten nugget 55 is hardly formed in the vicinity of the first member 3. can do. Therefore, the softening of the first member 3 due to the heat of the molten nugget 55 can be suppressed.

  Further, in the rivet 1 of the present embodiment, the centers of the head raised portion 11 a, the shaft tip raised portion 13 a, and the shaft portion 13 are all located on the axis O <b> 1 that is the central axis of the shaft portion 13. When the center of the head raised portion 11a is displaced from the central axis of the rivet 1, the electrodes 51 and 52 are displaced when the electrodes 51 and 52 are displaced in a direction opposite to the direction of displacement of the head raised portion 11a with respect to the radial direction of the rivet 1. In some cases, 51 does not come into contact with the head raised portion 11a, but comes into contact with a portion of the head 11 where the head raised portion 11a is not formed. Further, when the center of the shaft tip raised portion 13a is deviated from the center axis of the rivet 1, the electrodes 51 and 52 are displaced in the same direction as the direction of displacement of the shaft tip raised portion 13a with respect to the radial direction of the rivet 1. The molten nugget 55 may be formed in the vicinity of the first member 3. In the rivet 1 described above, the electrodes 51 and 52 are not easily detached from the head raised portion 11a, and the formation of the molten nugget 55 in the vicinity of the first member 3 can be reliably suppressed.

  Furthermore, in the rivet 1 of the present embodiment, the entire orthographic projection surface of the shaft tip raised portion 13a is located within the orthographic projection surface of the head raised portion 11a. Therefore, since the shaft tip raised portion 13 a is relatively small, it is possible to prevent the molten nugget 55 generated between the shaft tip raised portion 13 a and the second member 5 from greatly deviating from the center of the rivet 1. Therefore, it is possible to reliably suppress the first member 3 from being softened by the heat of the molten nugget 55.

  In addition, in the rivet 1 of the present embodiment, the insulating coating 15 is formed on a portion excluding the head raised portion 11a and the shaft tip raised portion 13a. In the case where a plurality of rivets 1 are provided, when the rivet 1 arranged adjacent to the rivet 1 is spot-welded to the second member 5 after spot-welding one rivet to the second member 5, the welding current is already welded. A so-called diversion that flows toward the rivet 1 is likely to occur. Therefore, welding is not performed appropriately, and the joining strength of the rivet 1 to the second member 5 may be reduced. On the other hand, in the rivet 1 of the present embodiment, the presence of the insulating coating 15 prevents the welding current from flowing toward the already welded rivet 1. Thereby, said problem can be reduced and also the electric corrosion which arises between the rivet 1 and the 1st member 3 can be prevented.

  Further, in the rivet 1 of the present embodiment, a groove 11 b is formed around the shaft portion 13 on the bottom surface of the head 11. Therefore, when the rivet 1 is caulked and fastened to the first member 3, the first member 3 enters the groove 11b of the rivet 1, so that the fastening force of the rivet 1 to the first member 3 can be further increased.

  Moreover, in the manufacturing method of the dissimilar-material joined body 10 of this embodiment, before the lamination | stacking process of stacking and arrange | positioning the 2nd member 5 on the dissimilar-material joining structure 20, the 1st of the dissimilar-material joining structure 20 in the 2nd member 5 is carried out. An insulating film forming step of forming an insulating film 5a on the surface overlapping the one member 3 is performed. Therefore, electrolytic corrosion caused by the difference in potential difference between the first member 3 and the second member 5 can be prevented.

  Next, a second embodiment of the present invention will be described with reference to FIG. The main difference between the present embodiment and the first embodiment is that the rivet 101 of the present embodiment replaces the head raised portion 11a and the shaft tip raised portion 13a of the rivet 1 of the first embodiment with a head electrical conducting portion 111a. The shaft tip electrical conduction portion 113a is provided. Since other configurations are substantially the same as those of the first embodiment, the same reference numerals are used and description thereof is omitted as appropriate.

  On the surface of the rivet 101 of the embodiment, an insulating coating 115 is formed in a portion excluding the head electrical conduction portion 111a and the shaft tip electrical conduction portion 113a. The center of the head electrical conduction portion 111 a and the center of the shaft tip electrical conduction portion 113 a are both located on the central axis of the shaft portion 113. All of the orthographic projection surfaces of the head electrical conducting portion 111 a and the shaft tip electrical conducting portion 113 a are located within the orthographic projection surface of the shaft portion 113.

  According to the rivet 101 of the present embodiment, as in the case of the rivet 1 of the first embodiment, when spot welding is performed, the resistance spot welding electrode 51 disposed on the rivet 101 side is the head electrical formed on the head 111. It contacts the conduction part 111a. A molten nugget 55 is formed between the shaft tip electrical conducting portion 113 a formed on the shaft portion 113 of the rivet 101 and the second member 5. Therefore, even when the center positions of the electrodes 51 and 52 are deviated from the center position of the rivet 101, the molten nugget 55 can be hardly formed in the vicinity of the first member 3. Therefore, the softening of the first member 3 due to the heat of the molten nugget 55 can be suppressed.

  Next, the present invention will be specifically described with reference to examples.

In Examples and Comparative Examples of the present invention, a plate-shaped first member 30 mm wide made of JIS standard aluminum alloy material AA6022 (thickness 1.2 mm), mild steel rivets, and JIS standard SPCC (thickness) A plate-shaped second member having a width of 30 mm and a width of 1.0 mm was used. And after manufacturing the dissimilar material joining structure by piercing and piercing the rivet into the first member, the longitudinal ends of the dissimilar material joining structure and the second member are wrapped at 30 mm × 30 mm. A lap joint was formed, and the rivet was spot-welded to the second member while the rivet and the second member were sandwiched between a pair of electrodes, and a test piece having a total length of 100 mm was manufactured. The welding conditions were an electrode pressure of 1.96 kN, a welding current of 7 kA, and an energization time of 10 cycles. The electrode used is made of a chromium copper alloy, and is a DR type having a diameter of 16 mm and a tip curvature radius of R300 mm.

  In the rivet of Example 1-5, a head bulge is formed at the head, and a shaft tip bulge is formed at the tip of the shaft. The rivet has a head diameter of 10 mm, a head thickness of 1 mm, a shaft diameter of 6 mm, a shaft length of 1 mm, a head raised portion diameter of 5 mm, and a shaft tip raised portion diameter of 4 mm. On the other hand, the rivet of Comparative Example 1-5 does not have the head raised portion and the shaft tip raised portion of the rivet of the embodiment.

  Example 1-5 was performed by changing the distance between the center of the rivet and the center of the electrode to 0 mm, 1 mm, 2 mm, 4 mm, and 6 mm so that the amount of displacement of the electrode position with respect to the center of the rivet during spot welding changes. And the test piece of Comparative Example 1-5 was manufactured.

  The “joint strength” shown in Table 1 is evaluated as follows. That is, the tensile test which adds a load to a mutually opposing direction along a longitudinal direction was performed with respect to the structure for a different material joining of a test piece, and the 2nd member. And the load which a junction part fractures | ruptures was measured. When the load was 4 kN or more, ◎ was evaluated as ◎ when less than 4 kN and 2 kN or more, and Δ when it was less than 2 kN.

  From Table 1, in Example 1-5, even when the distance between the center of the rivet and the center of the electrode is large and the electrode is greatly deviated from the center of the rivet, the molten nugget formed between the shaft tip raised portion and the second member It can be seen that the center of is not offset from the center of the rivet. And it turns out that joint strength is high in all Examples 1-5. On the other hand, in Comparative Example 1-3, as the distance between the center of the rivet and the center of the electrode increases, the center of the molten nugget formed between the shaft tip raised portion and the second member deviates greatly from the center of the rivet. I understand that. And the joint strength of the comparative example 2 has fallen a little, and the joint strength of the comparative example 3 has fallen remarkably. This is presumably because the portion around the shaft portion of the first member is softened due to the center of the molten nugget being displaced from the center of the rivet.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments and examples, and various design changes can be made as long as they are described in the claims. is there.

  The metal material constituting the first member, the second member, and the rivet is not limited to aluminum alloy or steel, and the metal material constituting the rivet has a higher melting point than the metal constituting the first member and the second member Any metallic material may be used as long as the base material is the same as the metallic material constituting the rivet. For example, the metal material constituting the rivet and the second member is not limited to the same type or the same composition, and the base components may be the same. Examples of the metal material having the same base component include ordinary steel, special steel, plated steel, high-strength steel, stainless steel, mild steel, etc., which are iron-based alloys, or JIS standard 2000-7000 series alloys, which are aluminum alloys, etc. Is mentioned.

  The form of the first member and the second member is not limited to being a plate-like member, and may be, for example, a hollow member such as a cylinder or a square tube, and the material type is in addition to the plate-like member. It may be an extruded material, a die-cast material, a casting material, or the like.

  The shape of the head raised portion of the rivet head, the shape of the shaft tip raised portion at the tip of the shaft portion, and the shape of the head may be any shape. That is, the planar view shapes of the head raised portion, the shaft tip raised portion, and the head are not limited to a circle, and may be, for example, an ellipse or a polygon. Further, the shape of the head raised portion is not limited to that having a rectangular cross section and a flat top surface as in the first embodiment described above. That is, as shown in FIG. 8A, the entire upper surface of the head 211 is a curved surface that is convex upward, and the head 211 protrudes most on the side opposite to the shaft portion 213 side, and is spot-welded. The portion that comes into contact with the electrode, that is, the central portion of the head 211 may be the head raised portion 211a. Further, the shape of the shaft tip bulge is not limited to that having a rectangular cross section as in the first embodiment. That is, as shown in FIG. 8B, a trapezoidal protrusion having a cross-sectional shape extending upward is formed at the tip end of the shaft portion 313, and protrudes most at the tip portion of the shaft portion 313. In this case, a portion that contacts the second member, that is, a flat portion at the center of the tip of the shaft portion 313 may be a shaft tip raised portion 313a. Further, as shown in FIG. 8C, a taper 411 c may be formed at the edge of the lower surface of the head 411. Furthermore, a pin-like projection (projection) may be provided on the raised portion at the tip of the shaft.

  In the dissimilar material bonded body or the dissimilar material bonding structure, the number of rivets may be any number of 1 or more, and the arrangement of the rivets is also arbitrary. The insulating coating formed on the rivet may be formed on at least a portion in contact with the first member.

  The insulating film formed on the rivet is not limited to a film that does not conduct electricity completely. What is necessary is just to have a large electrical resistance and high insulation compared with the part in which the insulating film in a rivet is not formed.

  If the plastic flow of the first member at the time of rivet caulking is sufficient, there may be no groove formed on the surface of the rivet head facing the first member.

  The insulating coating formed on the surface of the second member that overlaps the first member of the dissimilar material bonding structure only needs to have an insulating property that can prevent a battery formed between the first member and the second member. . Moreover, this insulating coating may be formed in any one of the surfaces which overlap the 2nd member in a 1st member, and may be formed in both the 1st member and the 2nd member. Furthermore, such an insulating coating does not have to be formed unless the environment is corrosive.

  The center of the head raised portion, the shaft tip raised portion, and the shaft portion may not be coaxial. Further, the center of the head electrical conduction part, the shaft tip electrical conduction part, and the shaft part may not be coaxial.

  The entire orthographic projection surface at the tip of the shaft viewed from the axial direction may not be located within the orthographic projection surface of the head raised portion. Further, the whole orthographic projection surface of the shaft tip electrical conducting portion as viewed from the axial direction may not be located within the orthographic projection surface of the head electrical conducting portion.

1, 101, 201, 301, 401 Rivet 3 First member 5 Second member 5a Insulating coating (second insulating coating)
10 Dissimilar materials 11, 111, 211, 311, 411 Head 11a, 211a, 311a, 411a Head raised portion 11b Groove 13, 113, 213, 313, 413 Shaft portion 13a, 213a, 313a, 413a Shaft end raised portion 15 Insulating coating (first insulating coating)
20 Dissimilar material joining structure 111a Head electrical conduction portion 113a Shaft end electrical conduction portion

Claims (11)

A rivet for fastening a joint formed by overlapping a first member made of a metal material and a second member made of a metal material having a melting point higher than that of the metal material constituting the first member,
The rivet is made of a metal material having the same main component as the second member,
The rivet has a plate-like head that is caulked and fastened to the first member, and a shaft portion that extends from the head and penetrates the first member and has a tip that is spot welded to the second member. And
The plate-like head and the shaft tip are respectively provided with a head raised portion and a shaft tip raised portion,
The orthographic projection surfaces of the head raised portion and the axial tip raised portion as viewed from the axial direction of the shaft portion overlap each other at the center of the orthographic projection surface of the shaft portion, and both are entirely the shaft portion. A rivet characterized by being located within the orthographic projection plane.   2. The rivet according to claim 1, wherein a center of each of the head raised portion, the shaft tip raised portion, and the shaft portion is coaxially located.   The rivet according to claim 1 or 2, wherein the whole orthographic projection surface of the shaft tip bulge portion as viewed from the axial direction of the shaft portion is located within the orthographic projection surface of the head bulge portion.   The first insulating film is formed on a portion excluding the head raised portion and the shaft tip raised portion and in contact with at least the first member. Rivet according to item 1. A rivet for fastening a joint formed by overlapping a first member made of a metal material and a second member made of a metal material having a melting point higher than that of the metal material constituting the first member,
The rivet is made of a metal material having the same main component as the second member,
The rivet has a plate-like head that is caulked and fastened to the first member, and a shaft portion that extends from the head and penetrates the first member and has a tip that is spot welded to the second member. And
A portion excluding the head electrical conduction portion on the plate surface of the head and the shaft tip electrical conduction portion at the tip of the shaft portion is covered with a first insulating film,
The orthographic projection surfaces of the head electrical conduction portion and the shaft tip electrical conduction portion viewed from the axial direction of the shaft portion overlap each other at the center of the orthographic projection surface of the shaft portion, A rivet characterized by being located in the orthographic projection plane of the shaft portion.   The rivet according to claim 5, wherein the head electrical conduction part, the shaft tip electrical conduction part, and the shaft part are all located coaxially.   The whole orthographic projection surface of the shaft tip electrical conducting portion viewed from the axial direction of the shaft portion is located within the orthographic projection surface of the head electrical conducting portion. rivet.   The rivet according to any one of claims 1 to 7, wherein a groove is formed around the shaft portion on a surface of the head facing the first member.   A dissimilar material bonding structure in which the rivet according to any one of claims 1 to 8 is caulked and fastened. A dissimilar material bonding structure manufacturing process for manufacturing a dissimilar material bonding structure by caulking and fastening the rivet according to any one of claims 1 to 8 to the first member;
A stacking step of stacking and arranging the second member on the tip side of the shaft portion of the rivet in the first member of the dissimilar material bonding structure;
A welding step of sandwiching the head portion of the rivet and the second member with a pair of resistance spot welding electrodes and spot welding the tip of the shaft portion of the rivet and the second member. Manufacturing method of dissimilar material joined body.   11. The dissimilar material joined body according to claim 10, further comprising an insulating film forming step of forming a second insulating film in a portion where the first member and the second member overlap before the laminating step. Manufacturing method.

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