WO2022045014A1

WO2022045014A1 - Method for joining dissimilar materials, and rivet used for same

Info

Publication number: WO2022045014A1
Application number: PCT/JP2021/030629
Authority: WO
Inventors: 哲岩瀬; 美速今村; 真三樹奥田; 舞吉澤
Original assignee: 株式会社神戸製鋼所
Priority date: 2020-08-28
Filing date: 2021-08-20
Publication date: 2022-03-03
Also published as: CN115605312A; JP7405717B2; JP2022039534A

Abstract

An aluminum material, which serves as a first member, to which a rivet comprising a head section and a shaft section is attached, and a steel material, which serves as a second member, are positioned so as to overlap, with a resin layer sandwiched between the surface of the steel material and the face on the tip-side of the shaft section of the aluminum material rivet. The rivet and the steel material are sandwiched by a pair of electrodes, and a current is passed between the electrodes in a pressurized state while performing spot welding while eliminating the resin layer between the electrodes. In the rivet, an annular stepped section, which is formed along the circumferential direction and protrudes in the axial direction, is provided to a connection section that is connected with the shaft section on the underside of the head section.

Description

Dissimilar material joining method and rivets used for this

The present invention relates to a method for joining dissimilar materials and a rivet used therein.

In recent years, efforts have been made to improve fuel efficiency by reducing the weight of the vehicle body of transport aircraft such as automobiles in response to global environmental problems caused by exhaust gas and the like. In order to improve the safety of automobiles in the event of a collision without hindering the weight reduction of the automobile body as much as possible, some of the steel materials that have been conventionally used for the automobile body structure are made lighter and more energy-absorbent. The number of applications in which light alloy materials such as excellent aluminum alloy materials are replaced is increasing.

Unless all parts of the car body are made of aluminum alloy material, these aluminum alloy materials need to be used in combination with steel materials (steel members) such as steel plates or shaped steels that are originally used in ordinary automobile bodies. .. Therefore, it is inevitably necessary to join dissimilar metals between an aluminum alloy material and a steel material (dissimilar material joining). Such a dissimilar material joining method is disclosed in Patent Document 1.

Further, in many cases, an adhesive layer is provided between the aluminum alloy material and the steel member in order to prevent corrosion (electrolytic corrosion) due to the potential difference between the two and to further secure the bonding strength. Patent Document 2 discloses a joining method for providing such an adhesive layer.

Japanese Patent Application Laid-Open No. 2010-207988 Japanese Patent Application Laid-Open No. 2015-24436

However, in the joining method of Patent Document 2, since the metals do not come into contact with each other in the portion where the adhesive is present, it is necessary to remove the adhesive in advance from the portion where the rivet is welded. This adhesive removal process is very time-consuming and impractical.
Therefore, it is desirable to apply the so-called weld bond method, in which the adhesive is left as it is and the adhesive is removed during spot welding. However, if the weld bond method is applied as it is, sparks and dust are likely to be generated from the welded portion, and it becomes difficult to obtain a desired nugget shape, and as a result, the joint strength is lowered. This is not limited to joining different materials of aluminum and steel, but also occurs in combinations of other different materials.

The present invention solves the above-mentioned problems, and provides a dissimilar material joining method capable of suppressing the generation of dust and the like and performing good spot welding in a weld bond method using rivets, and a rivet used therefor. The purpose.

The present invention has the following configuration.
(1) The shaft portion of the rivet having the head portion and the shaft portion is driven into the first member to penetrate the rivet.
A resin layer is provided between the first member to which the rivet penetrates and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. Place them on top of each other with the rivets in between.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
When the rivet is driven into the first member and attached, the annular stepped portion presses the first member, and the inner peripheral edge portion of the through hole of the shaft portion in the first member is moved to the second member side. Forming a protruding annular protrusion,
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
(2) The first member provided with the prepared hole and the annular protrusion on the peripheral edge of the prepared hole is arranged so as to be overlapped with the second member with the resin layer interposed therebetween.
The shaft portion of the rivet weldable to the second member having the head and the shaft portion is passed through the prepared hole of the first member.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
(3) A rivet having a head and a shaft.
A resin layer is provided between the first member, which is attached through the shaft portion, and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. The rivet and the second member are sandwiched between a pair of electrodes, and the resin layer is spot-welded while being energized while being pressurized between the electrodes. Used for joining,
A rivet provided with an annular stepped portion formed along the circumferential direction and protruding in the axial direction at a connection portion with the shaft portion on the back side of the head.

According to the present invention, in the weld bond method using rivets, dissimilar materials can be joined by good spot welding that suppresses the generation of dust and the like.

FIG. 1A is an external perspective view of a rivet used in the dissimilar material joining method according to the present invention. FIG. 1B is an external perspective view of a rivet used in the dissimilar material joining method according to the present invention. FIG. 2 is a process explanatory view showing the rivet driving process step by step in (A) to (C). FIG. 3A is a cross-sectional view of the aluminum material in which the rivets are driven. FIG. 3B is a bottom view seen from below of FIG. 3A. FIG. 4 is a process explanatory view showing a state in which an aluminum material into which rivets have been driven is overlapped with a steel material with a resin layer interposed therebetween. FIG. 5 is a process explanatory view showing a state of resistance spot welding of an aluminum material and a steel material using rivets. FIG. 6 is an explanatory diagram showing the state from the pressurization between the electrodes to the energization stepwise in (A) to (C). FIG. 7 is a process explanatory view showing other methods of fixing the rivet to the aluminum material by (A) and (B). FIG. 8 is a cross-sectional view showing another configuration of the dissimilar material joint shown in FIG. FIG. 9A is a partially enlarged cross-sectional view showing another shape of the annular stepped portion of the rivet. FIG. 9B is a partially enlarged cross-sectional view showing another shape of the annular stepped portion of the rivet. FIG. 9C is a partially enlarged cross-sectional view showing another shape of the annular stepped portion of the rivet.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the dissimilar material joining method of the present invention, an annular stepped portion protruding in the axial direction is provided on the back side of the head of the rivet to be used. Here, a method of joining dissimilar materials by joining an aluminum material and a steel material using steel rivets is illustrated, but the combination of materials of each member to be joined is arbitrary.

<Rivet composition>
1A and 1B are external perspective views of rivets used in the dissimilar material joining method according to the present invention.
The rivet 11 is made of steel and has a disk-shaped head portion 13 and a shaft portion 15 coaxially connected to the center of the head portion 13. The rivet 11 is formed at the connection portion with the shaft portion 15 on the back side of the head portion 13 (inner peripheral portion of the annular head back surface 13a) along the circumferential direction so as to surround the shaft portion 15 and protrudes in the axial direction. An annular stepped portion 17 is provided. The annular stepped portion 17 serves as an outer peripheral edge at the corners and corners due to the step, that is, the corner portion 17a connected to the back surface 13a of the head, the corner portion 17b connected to the side surface 15b of the shaft portion, and the protruding tip. Each of the corner portions 17c is chamfered in a curved shape in the axial cross section.

The shaft portion 15 shown in FIGS. 1A and 1B has a columnar shape having a constant diameter, but may have a shape that gradually increases from the base end on the head 13 side toward the tip end, and the shaft cross section has a shaft cross section. It may be an ellipse.

The tip surface (shaft tip surface) 15a of the shaft portion 15 is a curved surface protruding in the axial direction. The curved top portion 19 of the shaft portion tip surface 15a coincides with the central axis L of the shaft portion 15. Further, instead of the curved surface, a conical shape (projection) may be formed in which the top portion 19 is a protruding tip.

<Procedure of dissimilar material joining method>
Next, a procedure for joining the aluminum material and the steel material to different materials by using the above rivet 11 will be described.
FIG. 2 is a process explanatory view showing the driving process of the rivet 11 step by step in (A) to (C).
As shown in FIG. 2A, the aluminum material 23 is placed on the die 21 having a cylindrical upper portion, and the rivet 11 is placed above the die 21. An annular recess 21a is formed on the inner peripheral side of the upper surface of the die 21. Then, the head 13 of the rivet 11 is driven toward the aluminum material 23 by the punch 25.

As the aluminum material 23, a wrought material of 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series aluminum alloy, or 1000 series pure aluminum can be used. From the viewpoint of weldability, 5000 series, 6000 series, and 7000 series aluminum alloys are particularly preferable. Further, the aluminum material 23 is not limited to the plate material, but may be an extruded member (pipe material, or a hollow, solid, deformed cross-section profile material) or a forged material (plate material, ribbed material). Further, the surface of the aluminum material 23 may be subjected to various surface treatments such as a blast treatment, an etching treatment, and a brush polishing treatment as a preliminary treatment. In that case, the organic matter on the surface of the aluminum material is removed, and the bonding quality is improved.

As shown in FIG. 2B, when the punch 25 is lowered and the rivet 11 is pushed into the aluminum material 23, the portion of the aluminum material 23 facing the shaft portion 15 is punched out by the shaft portion 15, and this punching is performed. The rivet (blank) 23A falls inside the die 21. Further, the rivet 11 is pressed toward the aluminum material 23 by the punch 25, and the aluminum material 23 is sandwiched between the head 13 and the die 21. As a result, the annular stepped portion 17 of the rivet 11 is pushed into the aluminum material 23, and the aluminum material 23 plastically flows into the recess 21a formed on the upper surface of the die 21.

Thus, as shown in (C) of FIG. 2, the shaft portion 15 of the rivet 11 penetrates the aluminum material 23, and the tip surface 15a of the shaft portion is exposed on the lower surface of the aluminum material 23. Further, the annular stepped portion 17 formed on the head 13 enters the aluminum material 23, and the rivet 11 is caulked and fixed to the aluminum material 23. Further, an annular protrusion 26 is formed in which the inner peripheral edge portion of the through hole through which the shaft portion 15 of the aluminum material 23 penetrates protrudes toward the insertion direction of the shaft portion 15.

The driving of the rivet 11 may be performed at the same time as the press molding in, for example, the press molding step (trimming step) of the aluminum material 23. That is, when the aluminum material 23 is press-molded, a punch is installed in the press mold, or the press mold itself is used instead of the punch, and the rivet 11 is punched out at the same time as the press mold is lowered. As a result, the rivet 11 is caulked and fixed to the aluminum material 23. In this state, when the aluminum material 23 is conveyed to the resistance spot welding line, the rivet 11 is caulked and fixed to the aluminum material 23, so that the rivet 11 does not fall during the transfer process. Therefore, the workability of joining can be improved.

FIG. 3A is a cross-sectional view of the aluminum material 23 into which the rivet 11 is driven, and FIG. 3B is a bottom view seen from below of FIG. 3A.
The annular protrusion 26 of the aluminum material 23 shown in FIG. 3A is formed to be equal to or lower than the height of the outer peripheral edge 31 of the shaft portion tip surface 15a with respect to the axial direction of the shaft portion 15 of the rivet 11. That is, the annular protrusion 26 does not protrude from the shaft portion 15. The radial outer side of the annular protrusion 26 of the aluminum material 23 is not affected by the pushing by the annular stepped portion 17 of the rivet 11 and the plastic flow into the recess 21a (see FIG. 2) of the die 21, and has the original shape. It is a flat surface 23a of. That is, the flat surface 23a of the aluminum material 23 is recessed from the annular protrusion 26 by a distance S.

Therefore, the axial positions of the rivet 11 and the aluminum material 23 in FIG. 3A are in the order of the top portion 19, the outer peripheral edge 31, the annular protrusion 26, and the flat surface 23a of the shaft portion tip surface 15a from the lower side.

FIG. 4 is a process explanatory view showing a state in which the aluminum material 23 into which the rivet 11 is driven is overlapped with the steel material 29 with the resin layer 27 interposed therebetween.
A resin layer 27 is formed on one side surface of the steel material 29. The resin layer 27 is an adhesive that joins the aluminum material 23 and the steel material 29. Further, since the resin layer 27 has an electrical insulating property, it firmly joins the aluminum material 23 and the steel material 29 while preventing electrolytic corrosion due to contact with each other.

As the steel material 29, mild steel, high-strength steel, etc. can be used. A resin layer 27 is formed on one side surface of the steel material 29. The resin layer 27 is an adhesive that joins the aluminum material 23 and the steel material 29. Further, since the resin layer 27 has an electrical insulating property, it firmly joins the aluminum material 23 and the steel material 29 while preventing electrolytic corrosion due to contact with each other.

The adhesive used for the resin layer 27 may be applied to the steel material 29 in a liquid or viscous state, or may be applied to the aluminum material 23. Further, the resin layer 27 is not limited to the application of the adhesive, and a sheet-shaped adhesive sheet may be arranged. When an adhesive sheet is used, the adhesive sheet may be adhered to the steel material 29, the aluminum material 23, or both in advance, or may be adhered together when the aluminum material 23 and the steel material 29 are overlapped. As a result, the resin layer 27 is sandwiched and arranged between the surface of the aluminum material 23 on the tip end side of the shaft portion of the rivet 11 and the surface of the steel material 29.

FIG. 5 is a process explanatory view showing a state in which the aluminum material 23 and the steel material 29 are spot-welded by resistance using the rivet 11.
The aluminum material 23 provided with the rivet 11 and the steel material 29 overlapping the aluminum material 23 are sandwiched between the pair of

electrodes

33 and 35 at the positions of the rivets 11. Then, while pressurizing one of the

electrodes

33 and 35 toward the other by a pressurizing device (not shown), energization is performed between the electrodes by a power supply device (not shown) (current I). Then, a nugget 37 (see FIG. 6) having a desired size is formed between the shaft tip surface 15a of the rivet 11 and the steel material 29.

Here, a state in which the aluminum material 23 and the steel material 29 are pressed between the electrodes and energized between the electrodes to form the nugget 37 will be described in detail.
FIG. 6 is an explanatory diagram showing the state from the pressurization between the electrodes to the energization stepwise in (A) to (C).
As shown in FIG. 6A, the shaft tip surface 15a of the rivet 11 is pressed against the resin layer 27 by sandwiching the

electrodes

33 and 35 shown in FIG. 4, and the resin layer 27 presses the top 19 of the rivet 11. It is extruded radially outward in the center. Then, by energization between the electrodes, the resin layer 27 in contact with the tip surface 15a of the shaft portion of the rivet 11 is heated and melted, and flows outward in the radial direction (arrow M) or is partially sublimated. .. At this time, a slight gap is formed between the annular protrusion 26 and the steel material 29, and the resin layer 27 is smoothly discharged outward from this gap in the radial direction. As a result, the resin layer 27 is substantially completely discharged from the vicinity of the central axis L of the tip surface 15a of the shaft portion.

Then, as shown in FIG. 6B, in the vicinity of the central shaft L, the shaft portion tip surface 15a and the steel material 29 are in close contact with each other without the resin layer 27 intervening between them, and heating by energization is performed. The nugget 37 is formed by melting both of them. The nugget 37 grows from the central axis L as a starting point. At this time, the annular protrusion 26 is strongly pressed against the steel material 29 by the pressurization between the electrodes (arrow F).

As shown in FIG. 6C, the nugget 37 grows by energization, but on the radial outer side of the shaft portion 15 of the rivet 11, the annular protrusion 26 keeps pushing the steel material 29 strongly, so that the nugget 37 is a melted body. (Melted steel) is blocked and dust can be prevented.

In this way, the nugget 37 grows from the central axis L of the shaft portion 15 as a starting point with energization, and the rivet 11 and the steel material 29 are sufficient while suppressing the deviation from the central axis L and the generation of dust. It can grow to a size that gives a good bond strength.

As described above, since the rivet 11 is provided with the annular stepped portion 17, when the rivet 11 is driven into and attached to the aluminum material 23, the annular stepped portion 17 is the inner peripheral edge portion of the through hole of the shaft portion 15 in the aluminum material 23. The annular protrusion 26 is formed in the rivet. During spot welding, the annular protrusion 26 forms a gap between the aluminum material 23 and the steel material 29 on the radial outer side of the annular protrusion 26 by pressurization between the electrodes, and the resin layer 27 is smoothly formed from this gap. Is discharged to. Further, by energizing between the electrodes, a nugget 37 is generated starting from the central portion of the shaft portion 15 in which the resin layer 27 does not exist, and on the radial outer side of the shaft portion 15, the annular protrusion 26 acts as a weir to generate dust. To prevent.

According to this, even when dissimilar materials are joined via the resin layer 27 by resistance spot welding, a nugget of a desired size can be stably formed at the center of the shaft portion 15 without generating sparks and dust, which is necessary. Sufficient bonding strength can be obtained.

Further, since the rivet 11 is crimped to the aluminum material 23 by the annular stepped portion 17, the aluminum material 23 and the rivet 11 are crimped to the spot welded portion between the steel-steel similar materials of the rivet 11 and the steel material 29. It is possible to generate work hardening by the above method and further apply mutual bonding force (mechanical bonding force). Therefore, due to the synergistic effect of both spot welding and caulking, high joint strength as a dissimilar material joint can be obtained. Further, when the rivet 11 is pushed into the aluminum material 23 and crimped, cracking on the aluminum material 23 side can be prevented.

<Other configuration examples>
In the above example, the rivet 11 is caulked and fixed to the aluminum material 23 by driving the rivet 11 into the aluminum material 23, but the method of fixing the rivet 11 to the aluminum material 23 is not limited to this.
FIG. 7 is a process explanatory view showing other methods of fixing the rivet 11 to the aluminum material 23 by (A) and (B).

As shown in FIG. 7A, a prepared hole 23b having an inner diameter through which the shaft portion 15 of the rivet 11 can penetrate is provided in advance at the portion where the rivet 11 of the aluminum material 23 is provided. When forming the prepared hole 23b, for example, using the die 21 shown in FIG. 2 described above and a punch having an outer shape of the annular stepped portion 17 of the rivet 11, as shown in FIG. 7 (A). In addition, an annular protrusion 26 is formed on the peripheral edge of the prepared hole 23b. Then, as shown in FIG. 7B, the shaft portion 15 of the rivet 11 is passed through the prepared hole 23b by a press or the like to fix the rivet 11 to the aluminum material 23.

The annular protrusion 26 of the prepared hole 23b may be formed so as to protrude from the aluminum material 23 after the rivet 11 is fixed, and the forming method thereof is not limited.

The caulking joint of the rivet 11 to the aluminum material 23 may be performed, for example, in the press molding process of the vehicle body when the aluminum material 23 is a vehicle body structural material of an automobile. Further, apart from such a press forming process, it may be carried out in a process before and after the press forming process, for example, an aluminum plate manufacturing process or the like.

FIG. 8 is a cross-sectional view showing another configuration of the dissimilar material joint shown in FIG.
Here, another steel material 30 is superposed on the opposite side of the steel material 29 on the aluminum material 23 side. According to this configuration, by superimposing a plurality of

steel materials

29 and 30 and spot welding them to the rivet 11, three materials can be easily joined by one welding. By providing a plurality of

steel materials

29 and 30, the strength of the joined body can be improved and the applicable range of joining different materials can be expanded. The number of steel materials may be three or more, and the plate thickness may be the same or different. Similarly, with respect to the aluminum material 23, the number of sheets and the plate thickness are arbitrary as long as the annular protrusion 26 can be formed.

9A, 9B, and 9C are partially enlarged cross-sectional views showing another shape of the annular stepped portion of the rivet.
The annular stepped portion 17 of the rivet 11 is not limited to the shape shown in FIG. 1B. As shown in FIG. 9A, the annular stepped portion 17A may have a shape in which the

annular corner portions

17a and 17b and the annular corner portions 17c are at right angles to each other in the axial cross section. In this case, the bite of the aluminum material to the rivet 11 is improved, and the caulking joint strength can be improved.

Further, as shown in FIG. 9B, the annular stepped portion 17B is an inclined surface that expands radially outward from the corner portion 17b on the head back surface 13a side of the shaft portion side surface 15b toward the shaft portion tip surface 15a of the rivet 11. It may be an annular protrusion having 17d and a cylindrical surface 17e extending in the axial direction from the back surface 13a of the head and having a corner portion 17c formed at the tip thereof. In this case, when the annular stepped portion 17B is pressed against the aluminum material 23 as shown in FIG. 7B, the aluminum material enters between the cylindrical surface 17e and the shaft portion side surface 15b due to plastic flow. The portion including the corner portion 17c of the protrusion is deformed radially outward and bites into the aluminum material 23. As a result, the rivet 11 and the aluminum material 23 are crimped more firmly.

Then, as shown in FIG. 9C, the annular stepped portion 17C has the above-mentioned inclined surface 17d and the inclined surface 17f extending in the axial direction from the back surface 13a of the head and expanding radially outward toward the tip surface 15a of the shaft portion. May be an annular protrusion having a corner portion 17c formed at the tip thereof. In this case, the angle of the corner portion 17c in the shaft cross section is smaller than that in the case of the annular stepped portion 17B, the bite into the aluminum material 23 is good, and a stronger caulking state can be obtained.

<Rivet surface treatment>
Next, a process of forming a film on the surface of the rivet 11 will be described.
It is preferable to provide a zinc highly eutectic nickel plating film having a nickel eutectic ratio of, for example, 13 to 18% on the surface of the rivet 11.
The zinc highly eutectic nickel plating film preferably has a film thickness of 5 to 10 μm, and can have excellent corrosion resistance and heat resistance. As a result, electrolytic corrosion can be effectively prevented.

Further, it is preferable to further provide a chemical conversion film on the zinc highly eutectic nickel plating film of the rivet 11. This chemical conversion film may be a chromate film obtained by subjecting a chromate treatment (JIS H 0201) to the surface of a rivet plated with zinc highly eutectic nickel.
The chromate film is a thinner film than paints and the like, and can ensure high corrosion resistance and heat resistance. Further, in electrodeposition coating or the like after joining different materials, the adhesion of the paint is improved.
Further, instead of the chromate film, a zircon-based chemical conversion film may be formed. Examples of the zircon-based chemical conversion treatment include a chemical conversion treatment using zirconium phosphate. By using a zircon-based chemical conversion film, a chromium-free treatment can be performed.

The present invention is not limited to the above-described embodiment, and can be modified or applied by those skilled in the art based on the mutual combination of the configurations of the embodiments, the description of the specification, and the well-known technique. The invention is planned and is included in the scope for which protection is sought.

As described above, the following matters are disclosed in the present specification.
(1) The shaft portion of the rivet having the head portion and the shaft portion is driven into the first member to penetrate the rivet.
A resin layer is provided between the first member to which the rivet penetrates and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. Place them on top of each other with the rivets in between.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
When the rivet is driven into the first member and attached, the annular stepped portion presses the first member, and the inner peripheral edge portion of the through hole of the shaft portion in the first member is moved to the second member side. Forming a protruding annular protrusion,
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
According to this dissimilar material joining method, the resin layer can be reliably removed from the interface between the rivet and the second member, and the rivet and the second member can be satisfactorily spot welded without generating dust. Further, by driving the rivet into the first member, the rivet can be prevented from coming off, and the handleability and the workability of welding can be improved.

(2) The first member provided with the prepared hole and the annular protrusion on the peripheral edge of the prepared hole is arranged so as to be overlapped with the second member with the resin layer interposed therebetween.
The shaft portion of the rivet weldable to the second member having the head and the shaft portion is passed through the prepared hole of the first member.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
According to this dissimilar material joining method, the resin layer can be reliably removed from the interface between the rivet and the second member, and the rivet and the second member can be satisfactorily spot welded without generating dust. Further, since the process of inserting the rivet into the prepared hole of the first member can be performed at any timing such as the process before and after the press forming process of the first member or the press forming process, the process is free. The degree can be improved.

(3) The dissimilar material joining method according to (1) or (2), wherein a member of the same type as the second member is further superposed on the opposite side of the first member of the second member and spot welded.
According to this dissimilar material joining method, the strength of the joined body can be improved and the applicable range of dissimilar material joining can be expanded by providing a plurality of steel materials.

(4) The dissimilar material joining method according to any one of (1) to (3), wherein a zinc highly eutectic nickel plating film is provided on the rivet.
According to this dissimilar material joining method, the rivet can have excellent corrosion resistance and heat resistance.

(5) The dissimilar material joining method according to (4), wherein a chemical conversion film covering the zinc highly eutectic nickel plating film of the rivet is further provided.
According to this dissimilar material joining method, high corrosion resistance and heat resistance can be ensured, and the adhesion of the paint is improved in electrodeposition coating or the like after dissimilar material joining.

(6) The dissimilar material joining method according to (5), wherein the chemical conversion film is a chromate film.
According to this dissimilar material joining method, since it is a widely known treatment, a good film can be stably obtained even under various conditions.

(7) The dissimilar material joining method according to (5), wherein the chemical conversion film is a zirconium-based chemical conversion film.
According to this dissimilar material joining method, the chemical conversion film can be formed by a chrome-free treatment.

(8) A rivet having a head and a shaft.
A resin layer is provided between the first member, which is attached through the shaft portion, and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. The rivet and the second member are sandwiched between a pair of electrodes, and the resin layer is spot-welded while being energized while being pressurized between the electrodes. Used for joining,
A rivet provided with an annular stepped portion formed along the circumferential direction and protruding in the axial direction at a connection portion with the shaft portion on the back side of the head. According to this rivet, a resin layer is formed from an interface with a second member. It can be reliably removed and spot welded to the second member without generating dust. As a result, the joining strength at the time of joining different materials can be improved.

Note that this application is based on a Japanese patent application filed on August 28, 2020 (Japanese Patent Application No. 2020-144619), the contents of which are incorporated herein by reference.

11 Rivet 13 Head 13a Head back surface 15 Shaft 15a Shaft tip surface 15b

Shaft side surface

17, 17A, 17B, 17C Circular stepped part 17a Corner 17b Corner 17c Corner 17d Inclined surface 17e Cylindrical surface 17f Inclined surface 19 Top 21 Die 21a Recess 23 Aluminum material (first member)
23a Flat surface 23b Pilot hole 25 Punch 26 Circular protrusion 27 Resin layer 29 Steel material (second member)
30 Steel (same type of material)
31 Outer

peripheral edges

33,35 Electrodes 37 Nuggets

Claims

The shaft portion of the rivet having the head portion and the shaft portion is driven into the first member to penetrate the rivet.
A resin layer is provided between the first member to which the rivet penetrates and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. Place them on top of each other with the rivets in between.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
When the rivet is driven into the first member and attached, the annular stepped portion presses the first member, and the inner peripheral edge portion of the through hole of the shaft portion in the first member is moved to the second member side. Forming a protruding annular protrusion,
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
The first member provided with the prepared hole and the annular protrusion on the peripheral edge of the prepared hole is arranged so as to be overlapped with the second member with the resin layer interposed therebetween.
The shaft portion of the rivet weldable to the second member having the head and the shaft portion is passed through the prepared hole of the first member.
A dissimilar material joining method in which the rivet and the second member are sandwiched between a pair of electrodes, and spot welding is performed while energizing the electrodes while applying pressure while removing the resin layer from the electrodes.
The rivet is provided with an annular stepped portion formed along the circumferential direction and projecting in the axial direction at a connection portion with the shaft portion on the back side of the head portion.
By pressurizing between the electrodes during spot welding, a gap is formed between the first member and the second member on the radial outer side of the annular protrusion, and the resin layer is discharged into the gap. Spot weld,
Dissimilar material joining method.
The dissimilar material joining method according to claim 1, wherein a member of the same type as the second member is further superposed on the opposite side of the first member of the second member and spot welded.
The dissimilar material joining method according to claim 2, wherein a member of the same type as the second member is further superposed on the opposite side of the first member of the second member and spot welded.
The dissimilar material joining method according to any one of claims 1 to 4, wherein a zinc highly eutectic nickel plating film is provided on the rivet.
The dissimilar material joining method according to claim 5, further comprising a chemical conversion film covering the zinc highly eutectic nickel plating film of the rivet.
The dissimilar material joining method according to claim 6, wherein the chemical conversion film is a chromate film.
The dissimilar material joining method according to claim 6, wherein the chemical conversion film is a zirconium-based chemical conversion film.
A rivet with a head and a shaft,
A resin layer is provided between the first member, which is attached through the shaft portion, and the second member that can be welded to the rivet, between the tip end side of the shaft portion of the rivet of the first member and the second member. The rivet and the second member are sandwiched between a pair of electrodes, and the resin layer is spot-welded while being energized while being pressurized between the electrodes. Used for joining,
A rivet provided with an annular stepped portion formed along the circumferential direction and protruding in the axial direction at a connection portion with the shaft portion on the back side of the head.