Hybrid joining method for metal members

Abstract

To provide a metal member hybrid-joining method whereby metal members to which a plating film is applied can be stably joined.SOLUTION: A metal member hybrid-joining method includes: a mechanical joining step in which, while a recessed part 2a of a to-be-joined member 2 made of metal is kept fitted on a projecting part 1c of a joining member 1 made of metal, both the members are pressurized in a direction of compression, thereby flattening an end-face outer periphery of the projecting part of the joining member outward to form an undercut portion 1ca and integrally join both the members; and a step in which the end-face outer periphery of the projecting part is flattened outward until a plating film or an oxide film on an end face 10 of the projecting part of the joining member is torn in the mechanical joining step, thereby joining exposed new surfaces of both the members.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention is directed to joining metal members together using a plurality of joining methods. Hybrid joining method for metal members Regarding. [Background technology]

[0002] Conventionally, when manufacturing a composite member by joining a joining member and a joined member made of a metallic material, a high degree of adhesion is required at the joint depending on the application of the composite member. For example, in the case of a lithium battery, lead wires or the like are attached to the electrode terminals by welding or the like, and therefore a composite member is required in which a copper member having high conductivity and an aluminum member having high corrosion resistance are joined to the electrode terminals with high adhesion so as not to increase electrical resistance. As a method for joining metal members that meets this type of requirement, the diffusion bonding method described in Japanese Patent Publication No. 59-52031 (Patent Document 1), Japanese Patent Publication No. 64-4581 (Patent Document 2), etc. is known to be an optimal method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 59-52031 [Patent Document 2] Special Publication No. 64-4581 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an oxide film or impurities are present at the bonding interface, the diffusion bonding cannot be performed because it is impossible to remove them. Similarly, when one of the components is coated with a plating film of a metal that is difficult to diffuse bond, the plating film remains at the joint between the two components with a general integral bonding method, which also makes diffusion bonding impossible.

[0005] The present invention has been invented to solve the above problems, and is a method for stably joining metal members having a plated coating. Hybrid joining method for metal members The purpose is to provide. [Means for solving the problem]

[0006] The above-mentioned problem is solved by a mechanical joining process in which the convex portion of a metal joining member is fitted into the concave portion of a metal joined member, and pressure is applied to both members in a compressive direction to flatten the outer periphery of the end face of the convex portion of the joining member outward to form an undercut portion and join the two members together; and a method for joining the two members together in which the outer periphery of the end face of the convex portion of the joining member is flattened outward until the plated film or oxide film on the end face of the convex portion of the joining member is torn, thereby exposing the plated film or oxide film. The newly formed surface of the joining member and the joined member This problem can be solved by a hybrid joining method for metal members, which joins metal members by a diffusion bonding process. [Effects of the Invention]

[0007] According to the present invention described above, the mechanical joining process The two components are joined together in both the first and second processes. A composite member with high adhesion can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams showing a hybrid joining method for metal members according to an embodiment of the present invention, in which FIG. 1A is a diagram showing a mechanical joining process and FIG. 1B is a diagram showing a diffusion joining process. [Figure 2] 1A to 1C are explanatory views showing the order of mechanical joining steps of a hybrid joining method for metal members according to an embodiment of the present invention. [Figure 3] 1 is a longitudinal cross-sectional view showing a hybrid joint structure of metal members according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The hybrid joining method and joining structure of metal members according to the present invention will be described below with reference to the drawings. The first joining method comprises a mechanical joining process shown in Figure 1(a) and Figures 2(a), (b), and (c) and a diffusion joining process shown in Figure 1(b).

[0010] The mechanical joining process includes a joining member 1 made of a copper material having a shaft portion 1a, a flange portion 1b, and a convex portion 1c, a joined member 2 made of a columnar aluminum alloy material having a recess 2a that abuts against the flange portion 1b and fits into the convex portion 1c, and a receiving mold 3 and a pressing mold 4 that are arranged so that these two members can be pressed together, and is configured to form a composite member CC by joining the joined member 2 to the joining member 1 by applying pressure with the pressing mold 4.

[0011] The receiving die 3 has an expanded hole 3a that guides a portion of the workpiece 2 and a positioning hole 3b that communicates with the expanded hole 3a and positions the shaft portion 1a of the joining member 1. A knockout pin 5 that extends concentrically with the positioning hole 3b is disposed so as to be able to protrude, with the end face of the knockout pin 5 configured to close the bottom of the positioning hole 3b. The knockout pin 5 is configured to position the flange portion 1b of the joining member 1 in the positioning hole 3b in the expanded hole 3a of the receiving die 3 and to expose the protrusion 1c of the joining member 1 from the receiving die 3. Furthermore, when the knockout pin 5 protrudes into the positioning hole 3b after the pressing die 4 retracts, the shaft portion 1a of the joining member 1 located in the positioning hole 3b is removed from the receiving die 3 together with the joined workpiece 2.

[0012] The mechanical joining step preferably includes a preforming die 6 having a preforming hole 6a as shown in Figure 2(a). The preforming die 6 is configured to preform the workpieces 2 to be joined into a pan-head-shaped portion 2b that fits into the protrusion 1c of the joining member 1. The preforming hole 6a of the preforming die 6 allows excess material of the workpieces 2 to extend in a direction intersecting the direction of pressure application. Furthermore, the preforming die 6 is configured to, during preforming of the workpieces 2, form a portion of the workpieces 2 that fits into the protrusion 1c of the joining member 1 into a shape that conforms to the expanded hole 3a of the receiving die 3 and to bring it into close contact with the flange 1b of the joining member 1.

[0013] 2(b) and (c), the press die 4 is configured to preform the workpieces 2, and then plastically deform the preformed pan-head-shaped portion 2b into a plate-like head portion 2d of a predetermined thickness to integrally join the two workpieces. Similar to the preforming die 6, the press die 4 is configured to work-harden the low-hardness workpieces 2 during the forming of the workpieces 2, increasing their hardness and pressing the high-hardness protrusions 1c of the workpieces 1 to be joined through the inner walls of the recesses 2a.

[0014] Although the joining member 1 is made of a copper material, it may be made of a metal material with higher hardness, such as an iron material.

[0015] As shown in Figure 1(b), the heating furnace 7 used in the diffusion bonding process needs only to be configured to heat the composite material CC placed inside the furnace, which is heated in an air atmosphere at 550°C, the eutectic point of copper and aluminum, for at least two hours, preferably about four hours. This causes a eutectic reaction at the joint of the composite material CC, generating a diffusion layer on the newly formed surface. Since the composite material placed in this heating furnace 7 can be diffusion bonded simply by being heated, a large number of composite materials CC can be placed in the heating furnace 7.

[0016] The diffusion bonding method is not limited to the liquid phase diffusion bonding described above, but may be solid phase diffusion bonding. In addition, it is preferable to heat the joining member and the joined member at a eutectic point and for a heating time that is appropriate for the materials of the joining member and the joined member.

[0017] In the hybrid joint structure CC formed by the hybrid joining method described above, as shown in Figure 3, during the mechanical joining process, the end face of the protruding portion 1c of the joining member 1, i.e., the upper end face 10, undergoes plastic deformation so that it extends in a direction intersecting the pressure direction, while the outer periphery of the upper end flattens outward, forming an undercut portion 1ca. As a result, the joined member 2 also undergoes plastic deformation, and its excess material wraps around the back surface 11 of the undercut portion 1ca, bringing the joined member 2 into close contact across the entire surface of the undercut portion 1ca. This mechanically joins the joining member 1 and the joined member 2 to produce a composite member CC. During this process, the plating coating covering the joining member 1, on the top surface of the undercut portion 1ca, is flattened outward and destroyed, resulting in its removal. Meanwhile, the plating coating on the back surface of the undercut portion 1ca is compressed, increasing its thickness.

[0018] Then, in the diffusion bonding process, the composite member CC formed in the mechanical bonding process is placed in a heating furnace 7 for the heating process and heated to a predetermined temperature. At this time, the plating coating has been removed from the upper end surface 10 of the undercut portion 1ca of the bonding member 1, and the bonding member 1 and the bonded member 2 are in close contact with each other, leaving no air gap between the two members and preventing atmospheric air from entering the joint. As a result, the newly formed surfaces of the two members constituting the joint are not covered by a new oxide film, resulting in very high adhesion between the two members, and a sufficiently thick diffusion layer is formed on the newly formed surfaces, as shown. This allows for the production of a composite member CC that is solid-solution strengthened and joined with a highly adhesive joint.

[0019] On the other hand, at the joining interface between the joining member 1 and the joined member 2, except for the upper surface 10 of the undercut portion 1ca, the plated coating is compressed and thickened during the mechanical joining process, which acts as a barrier to prevent the eutectic reaction from occurring.Since diffusion layers have poor durability, not forming a diffusion layer at the portion P where the joining interface is in contact with the external environment leads to improved quality.

[0020] The specific configuration of each part of the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0021] CC: Composite material 1 Joint material 1a Shaft part 1b Flange 1c Convex part 1ca Undercut part 2 Parts to be joined, 2a Recess 3. Receiving type 4 Press mold

Claims

[Claim 1] a mechanical joining process in which a convex portion of a metal joining member is fitted into a concave portion of a metal joinee member, and pressure is applied to both members in a compressive direction to flatten the outer periphery of the end surface of the convex portion of the joining member outward to form an undercut portion, thereby joining the two members together; a step of flattening the outer periphery of the end face of the convex portion of the joining member outward until the plating film or oxide film on the end face of the convex portion of the joining member is torn in the mechanical joining step, thereby performing diffusion bonding between the exposed new surface of the joining member and the joined member; A hybrid joining method for metal members, characterized by joining metal members by

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