JPH07164172A - Method for lap joining of metallic sheet - Google Patents

Abstract

PURPOSE:To improve the tensile strength and the fatigue strength of a joined zone by executing the laser beam welding of the adhered surface after the adhesive is applied to the lapped surface of two metallic sheets to execute the adhesion. CONSTITUTION:One end parts of two metallic sheets 1, 1 are lapped and joined with each other. In this work, the adhesive is applied to at least one of the lapped surfaces of two metallic sheets 1, 1 to execute the adhesion. The laser beam welding is executed on the center part of the adhered part 2 with one bead 3. After the laser beam welding, the material to be joined is heated to harden the adhesive. The filler metal is used in the laser beam welding. For example, the two component, room temperature setting adhesive is applied to two strip-shaped test specimens 1, 1 of the hot-rolled steel sheet for automobile and the high tensile steel sheet, and the laser beam welding is executed after one end parts are joined with each other. This constitution prevents generation of defective welding such as blowhole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining two metal plates in a superposed manner, which uses both the joining by an adhesive and the joining by laser welding.

[0002]

2. Description of the Related Art Conventionally, as a method of superposing and joining one end portions of two metal plates, a welding method or a method using an adhesive is generally used. In recent years, a weld bonding method using spot welding together has been performed in order to strengthen the adhesion by an adhesive. For example, when this method is applied to a car body of an automobile, after applying a thermosetting adhesive to the member, spot welding is performed and the adhesive is hardened in the process of paint baking.

[0003]

However, the joining by the above-mentioned weld bonding method has the following problems. (1) Since the melted and solidified portion called spot weld nugget has a round shape, stress concentration occurs, which becomes a starting point of static fracture or fatigue crack. (2) In spot welding, local pressure is applied to bond, so
The thickness of the adhesive becomes non-uniform, or the welded parts of the objects to be welded have a dent, which impairs the appearance.

Even if spot welding is changed to continuous welding such as arc welding in order to solve the above problems, there are the following problems. (1) The member is thermally deformed. (2) In arc welding, a melted portion is formed by heat conduction from the surface, but if an adhesive is present on the overlapping surface, heat conduction is impeded, so formation of the melted portion is hindered and good welding cannot be performed. Sometimes. (3) The heat causes the adhesive to decompose and become a gas, which causes the welded portion to be scattered. Also, this reduces the adhesive strength.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a method for superposing and joining metal plates which enables continuous welding in the presence of an adhesive. Has an aim.

[0006]

According to a first aspect of the present invention, there is provided a method for laminating and joining metal plates, wherein two metal plates are superposed on each other when the two end portions of the two metal plates are superposed and joined. After applying adhesive to at least one of the surfaces and bonding,
The adhesive surface is laser welded.

According to the second aspect of the present invention, there is provided a method for superposing and joining metal plates by heating at least one of the superposing surfaces of the two metal plates when the two end portions of the two metal plates are superposed and joined. After a curable adhesive is applied and superposed, and the superposed surfaces are laser-welded, the materials to be joined are heated to cure the adhesive and join them. According to a second aspect of the present invention, there is provided a metal plate lap joining method according to the first or second aspect of the present invention, wherein a filler metal is used for laser welding.

[0008]

In the lap joining method for metal plates according to the first aspect of the present invention, since the laser welding is used, the heat input amount is low, therefore the deformation of the members is small, and the adhesive is gasified to lower the adhesive strength. There is nothing to do. Further, since the energy is concentrated on a part, there is less welding failure due to the fact that the adhesive hinders heat conduction, as compared with the case of using general welding.

In the lap joining method of metal plates according to the second aspect of the present invention, since laser welding is performed after applying the thermosetting adhesive, the heating step of the joined body after laser welding is performed. Since the adhesive can be cured by utilizing it, it is not necessary to provide a heating step for heat curing the adhesive.

In the third method for superposing and joining metal plates according to the present invention, since the filler material is used, it is possible to prevent the adhesive from being altered by the laser during laser welding and to try to get into the molten metal. It is possible to prevent the occurrence of welding defects such as blow holes.

[0011]

[Examples] Hot-rolled steel sheets (SPHC) and high-tensile steel sheets (SPFH590) for automobiles with plate thicknesses of 3.2 mm and 1.6 mm
Two strips of test material are coated with a two-component separation type room temperature curing type adhesive or a one-component heat curing type adhesive, and one end is adhered or adhered to each other and then laser welded to pull the joint. Shear strength and tensile shear fatigue strength were measured and compared with the test results of the bonded body bonded with the adhesive alone. The results are shown in Table 1.

[0012]

[Table 1]

In the fatigue test, as shown in FIGS. 1 (a) and 1 (b), one end portion of two strip-shaped test materials 1 is bonded with an adhesive to form a central portion of the adhesive portion 2. The test was performed by laser welding with the bead 3 of No. 3, and tensile force was repeatedly applied in the longitudinal direction, and the number of repetitions was 1
0 ⁷ does not break beyond the times stress was the fatigue strength. A support 4 having the same plate thickness as that of the strip-shaped test material 1 was fixed to both ends of the test body so that a tensile force parallel to the joint surface acts.

As can be seen from Table 1, those joined by the method of the present invention are compared with those joined only by the adhesive,
It can be seen that both the tensile strength and the fatigue strength are excellent, and the effect of the present invention is excellent. In laser welding, it is advisable to increase the number of beads or change the direction of the beads according to the purpose of use of the materials to be joined.

[0015]

According to the present invention, it is possible to improve the tensile strength and the fatigue strength of a lap joint portion of two metal plates joined by an adhesive.

[Brief description of drawings]

FIG. 1 is a side view and (b) is a plan view showing a test agent used in a fatigue test.

[Explanation of symbols]

 1 Test piece 2 Adhesive part 3 Bead part 4 Support

Claims (3)

[Claims] 1. When two end portions of two metal plates are superposed and joined to each other, an adhesive is applied to at least one of the superposed surfaces of the two metal plates, and after adhering, the adhering faces are laser-welded. A method for superposing and joining metal plates, which is characterized in that 2. When two end portions of two metal plates are superposed and joined to each other, a thermosetting adhesive is applied to at least one of the superposition faces of the two metal plates to superpose each other, and the superposition faces are superposed. After laser welding, the materials to be joined are heated to cure and bond the adhesive material, and the joining is carried out. 3. The method for laminating and joining metal plates according to claim 1 or 2, wherein a filler is used for laser welding.