JP2017087281A - Joint structure and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a structure made of dissimilar metal material, such as aluminum material, to be joined to a structure made of steel material at higher strength without increasing costs.SOLUTION: A tip part 113 of a button component 101 is plunged from a surface side of an aluminum plate 103 to be pushed into the aluminum plate 103. Then, the tip part 113 of a shaft part 112 penetrates through the aluminum plate 103 to be placed in contact with a steel plate 102. In this state, the tip part 113 and the steel plate 102 are welded by well-known resistance spot welding.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a joining structure and method in which a structure made of a different material such as an aluminum material is joined to a structure made of steel.

  High strength is required for parts (body parts) constituting the vehicle. In addition to this, in recent years, lightweight has been required. For this reason, for example, high-tensile steel or aluminum material is used as the material for forming the component. Further, a composite member in which high-tensile steel and an aluminum material are integrated is used.

Japanese Patent Laying-Open No. 2015-062911

  However, for example, spot welding or the like is used in joining steel materials. However, in the joining of dissimilar materials as described above, there is no appropriate technique including manufacturing cost and strength to be obtained. There was a problem.

  The present invention has been made to solve the above-described problems, and a structure made of a dissimilar metal material such as an aluminum material has a higher strength than a structure made of steel material without causing an increase in cost. It aims to be able to join with.

  The joining method according to the present invention includes a first step of preparing a button part made of steel having a substantially T-shaped axial section, which is composed of a head part and a shaft part connected to the head and having a tapered tip part. , The second step of stacking the second part made of a material different from the steel material on the first part made of steel, and the button part is pushed in from the surface side of the second part and pushed in, and penetrates the second part And a third step of welding the tip part and the first part by resistance spot welding by bringing the tip part of the shaft part into contact with the first part.

  In the joining method, in the third step, the seat surface of the head is brought into contact with the surface of the second component.

  In the above-described joining method, in the third step, spot welding may be started after the tip portion of the shaft portion is brought into contact with the first component, and the shaft portion may be further pushed in.

  In the joining method described above, the head of the button part may have a shape that approaches the distal end side of the shaft part as the peripheral part.

  In the above-mentioned joining method, in the third step, one electrode in resistance spot welding is brought into contact with the head of the button part and pressed in the direction of the first part, so that the tip part of the button part enters the second part. Then, the second part is penetrated, the tip part of the shaft part is brought into contact with the first part, and the tip part and the first part are welded.

  The joining structure according to the present invention includes a first part made of steel, a second part made of a material different from the steel placed on the first part, and a tip penetrating the second part from the surface side. The part is composed of a shaft part welded to the first part and a head part to which the shaft part is connected, and is made of steel having a substantially T-shaped axial section, and the seating surface of the head part abuts against the surface of the second part. Button parts.

  In the above joint structure, the head of the button component may have a shape that approaches the tip end side of the shaft portion as the peripheral edge portion.

  As described above, according to the present invention, it is possible to obtain an excellent effect that a structure made of a dissimilar metal material such as an aluminum material can be bonded to a structure made of steel without increasing the cost. It is done.

FIG. 1 is an explanatory diagram for explaining a bonding method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating the bonding structure in the embodiment of the invention. FIG. 3 is a cross-sectional view illustrating another bonding structure in the embodiment of the invention. FIG. 4 is a photograph of a cross-section of the joint structure in the embodiment of the present invention observed with a metal microscope. FIG. 5 is a photograph of a cross-section of the joint structure in the embodiment of the present invention observed with a metal microscope.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a bonding method according to an embodiment of the present invention.

  First, in the first step S101, the button component 101 shown in FIG. The button component 101 includes a head part 111 and a shaft part 112 connected to the head part 111. The shaft portion 112 includes a tip portion 113 having a tapered shape. The button component 101 is made of steel such as carbon steel for cold heading, for example, and has a substantially T-shaped axial cross section. The head portion 111 and the shaft portion 112 are, for example, circular in plan view. The button component 101 has a shaft portion 112 with a diameter of 10 mm, for example. In addition, the shape (sectional shape) of planar view of the head part 111 and the axial part 112 may be not only circular but a polygon. Further, the head 111 may have a concave shape in the direction of the shaft portion 112 such as a concave polygon as well as a convex polygon.

  Next, in 2nd process S102, as shown in FIG.1 (b), the aluminum plate (2nd components) 103 comprised from the material different from steel materials is piled up on the steel plate (1st components) 102. As shown in FIG. Deploy. The steel plate 102 is a high-tensile steel plate such as JSC780 and JSC980Y, and has a thickness of 1 mm, for example. The aluminum plate 103 is an aluminum alloy plate such as an AL5952P material, and has a thickness of 1 mm, for example. The shaft 112 may be longer than the thickness of the aluminum plate 103.

Next, in the third step S103, as shown in FIG. 1C, the front end portion 113 of the button component 101 is inserted and pushed in from the surface side of the aluminum plate 103. Next, as shown in FIG. 1 (d), the aluminum plate 103 is penetrated so that the tip 113 of the shaft 112 is brought into contact with the steel plate 102. In this state, the tip portion 113 and the steel plate 102 are welded by well-known resistance spot welding. By welding, a nugget 104 in which these are melted and solidified is formed between the tip portion 113 and the steel plate 102. By the welding, the tip end portion 113 is deformed from the tapered shape. In spot welding, the pressing force (pressing force) may be 100 to 400 kgf · cm ² , the welding current may be 1000 to 14000 A, and 6 to 30 cycles.

  In the third step, when the welding is completed, the seating surface of the head 111 is brought into contact with the surface of the aluminum plate 103 as shown in FIG. In the third step, spot welding is started after the tip 113 of the shaft 112 is brought into contact with the steel plate 102, and the shaft 112 is further pushed in.

  Here, in the third step, one of the electrodes in resistance spot welding is brought into contact with the head 111 of the button part 101 and pressed in the direction of the steel plate 102, so that the tip 113 of the button part 101 enters the aluminum plate 103. Then, the aluminum plate 103 is penetrated, the tip 113 of the shaft 112 is brought into contact with the steel plate 102, and the tip 113 and the steel plate 102 are welded. The other electrode in resistance spot welding is electrically connected to the steel plate 102. In the above pushing operation, both electrodes are energized, so that resistance heating in the button component 101 softens (melts) the aluminum plate 103 in contact with the shaft portion 112 (tip portion 113), and the aluminum plate 103 penetrates. Becomes easy.

  As described above, the steel plate 102, the aluminum plate 103 placed on the steel plate 102, the aluminum plate 103 placed on the steel plate 102, and the shaft portion 112 penetrates the aluminum plate 103 from the surface side to the tip. A joint structure is obtained, which is composed of a button part 101 made of steel having a substantially T-shaped axial cross section in which a portion is welded to the steel plate 102 and the seating surface of the head 111 abuts against the surface of the aluminum plate 103.

  In the joining structure obtained by the joining method in the above-described embodiment, the aluminum plate 103 is pressed against the steel plate 102 by the head portion 111 of the button part 101 that is firmly welded to the steel plate 102 with the nugget 104. The nugget 104 serving as a welded portion is a portion where the steel plate 102 made of the same material and the button part 101 (tip portion 113) are melted and solidified, and high joint strength is obtained. As a result, according to the present invention, a structure made of a dissimilar metal material such as an aluminum material can be joined to a structure made of steel with higher strength. Further, since the button component 101 that can be manufactured at low cost is used and welding is performed by the existing resistance spot welding technique, the cost is not increased.

  By the way, as shown in FIG. 2, the aluminum plate 103 may be fixed to the steel plate 102 by the button part 201 in which the flange portion 211 a of the head portion 211 is shaped so as to approach the distal end side of the shaft portion 212 as the peripheral edge portion. . With this configuration, a groove region 231 is formed on the seating surface of the head 211. When the shaft portion 212 is plunged and pressed for spot welding, the aluminum plate 103 around the shaft portion 212 may be melted and scattered around. By forming the flange portion 211a having the above-described configuration, molten aluminum can be accommodated in the groove region 231 formed on the shaft portion 212 side (lower side) of the flange portion 211a, and scattering of the molten aluminum can be prevented.

  In addition, as shown in FIG. 3, the aluminum plate 103 may be fixed to the steel plate 102 by a button part 301 having a shape in which the flange portion 311 a of the head portion 311 is closer to the distal end side of the shaft portion 312 as the peripheral edge portion. The peripheral edge portion of the flange portion 311a is substantially parallel to the shaft portion 312 on the lower side in the axial direction. Also with the flange portion 311a configured as described above, molten aluminum can be accommodated in the groove region 331 formed below the flange portion 311a, and scattering of the molten aluminum can be prevented.

  Next, the result of observing the cross section of the state in which the aluminum plate is fixed to the steel plate using a button part made of SWCH (Steel Wire Cold Heading) 12 with a metal microscope will be described with reference to FIGS. . The produced button part has a shape in which the collar part of the head approaches the tip side of the shaft part as the peripheral part. The steel plate was a JSC780 material with a thickness of 0.8 mm, and the aluminum plate was an AL5952P material with a thickness of 1 mm. The button parts were made of carbon steel for cold heading. FIG. 5 is an enlarged view of a part of FIG. 4 and shows an enlarged view of the welded portion between the tip of the shaft part of the button part and the steel plate. As shown in FIG. 5, it is confirmed that the welded portion is melted and solidified.

  Next, the results of measuring the tensile shear adhesive strength (TSS) and the cross tensile adhesive strength (CTS) in the actually produced bonded structure will be described. As the steel plate, a JSC780 material (sample 1) having a thickness of 0.8 mm, a JSC980YL material (sample 2) having a thickness of 1.0 mm, and an aluminum plated steel plate (sample 3) having a thickness of 1 mm were used. Usibor 1500P (registered trademark, manufactured by Arcelor Mittal) was used as the aluminum-plated steel sheet. Moreover, the aluminum-plated steel plate used what was quenched. The aluminum plate was made of AL5952P material having a plate thickness of 1 mm in all samples. The button part was made of SWCH12 material, and the diameter of the shaft portion was 10 mm, and the diameter of the head in plan view was 22 mm. The measurement results are shown in Table 1.

  Table 2 shows a comparison of TSS and CTS with a joining structure obtained by another joining technique. Sample 4 is a bonded structure of an aluminum plate and a steel plate by self-piercing rivets. Sample 5 has a joint structure in which an opening is formed in an aluminum plate in advance, a shaft portion of a rivet is fitted into this opening, and the tip of the shaft portion and a steel plate are welded (see Patent Document 1). Sample 6 is a joint structure in which an aluminum plate and a steel plate are spot-welded with a delta spot. In either case, the same aluminum plate and steel plate as those of Sample 1 described above are used. Table 2 also shows the results of Sample 1.

  As shown in Table 1, sufficient bonding strength is obtained in various materials. In sample 3, the steel plate is an aluminum-plated steel plate, but it has been subjected to quenching treatment, and since the plating layer is extremely thin, a high bonding strength is obtained between the steel plate and the shaft tip of the button part. It is considered a thing.

  Moreover, as shown in Table 2, a high bonding strength is obtained as compared with other bonding techniques. The sample 5 uses the same rivet as the button part of the present invention, but there is a big difference in that the shaft end of the rivet is not inserted into the aluminum plate and pushed. In the joining structure according to the joining method of the present invention, since joining such as welding occurs with the second part also on the side surface of the button part, it is considered that higher joining strength is obtained as described above. It is done.

  As described above, according to the present invention, the tip part of the button part is inserted and pushed in from the surface side of the second part, the second part is penetrated, and the tip part of the shaft part is brought into contact with the first part. Since the tip part and the first part are welded by resistance spot welding, the structure of a dissimilar metal material such as an aluminum material has a higher strength than the structure made of steel without increasing the cost. It becomes possible to join with.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, the first component and the second component are not limited to plate members, and may be structures having other shapes. Further, the second component is not limited to the aluminum material, and may be any material made of a material different from the steel material. Further, the button part is not limited to the SWCH 12, and may be made of steel.

  DESCRIPTION OF SYMBOLS 101 ... Button part, 102 ... Steel plate (1st part), 103 ... Aluminum plate (2nd part), 104 ... Nugget, 111 ... Head, 112 ... Shaft part, 113 ... Tip part.

Claims (7)

A first step of preparing a button part made of steel having a substantially T-shaped axial section formed of a head portion and a shaft portion connected to the head portion and having a tapered tip portion;
A second step of stacking a second part made of a material different from steel on a first part made of steel;
The tip part of the button part is inserted and pushed in from the surface side of the second part, the tip part of the shaft part is brought into contact with the first part through the second part, and the tip part and the And a third step of welding the first part by resistance spot welding. The joining method according to claim 1,
In the third step, the joining method is characterized in that the seating surface of the head is in contact with the surface of the second component. The joining method according to claim 1 or 2,
In the third step, spot welding is started after the tip portion of the shaft portion is brought into contact with the first part, and the shaft portion is further pressed. In the joining method according to any one of claims 1 to 3,
The joining method according to claim 1, wherein the head part of the button part is shaped so as to approach the distal end side of the shaft part toward the peripheral part. In the joining method according to any one of claims 1 to 4,
In the third step, one of the electrodes in resistance spot welding is brought into contact with the head of the button part and pressed in the direction of the first part, so that the tip part of the button part enters the second part. The joining method is characterized in that the tip part of the shaft part is brought into contact with the first part, the tip part and the first part are welded, and the second part is penetrated. A first part made of steel;
A second part made of a material different from the steel material arranged to overlap the first part;
The second part is penetrated from the surface side and the tip part is composed of a steel part welded to the first part and a head part to which the shaft part is connected, and the axial section is made of steel having a substantially T-shape, And a button part that abuts the seating surface of the head against the surface of the second part. The joint structure according to claim 6,
The joint structure according to claim 1, wherein the head part of the button part is shaped so as to approach the tip part side toward the peripheral part.