JPH04143085A - Hot press welding method of aluminum material and copper material - Google Patents

Abstract

PURPOSE:To improve the strength stability and reliability of a joint part by butting a copper material, the joint end of which is formed to a projecting shape having a specific bevel angle, to an aluminum material and subjecting these materials to electrical heating and force pressurizing. CONSTITUTION:The joint end faces 10 of the aluminum material 2 and the copper material 4 are butted against each other and are electrically heated. The temp. increasing is concentrated to the joint surface 10a by the projecting part of the copper material 4, by which the deformation of the aluminum material 2 which has a low m.p. is accelerated and the flowability of the aluminum material 2 is improved. The extrusion of an alloy layer 14 is smoothed and the joint area is increased by specifying the bevel angle theta of the copper material 4 to 15 to 45 deg.. The extrusion of the alloy layer 14 is accelerated and the joint strength is increased by the strong pressurization. Then, the tensile strength and bending strength are increased in the basic hot press welding stage and the workability is thereby improved. In addition, the joint stability and reliability of the joint part are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for hot butt-joining aluminum and copper materials.

[Conventional technology]

For example, aluminum materials are often used as electrical conductors in electrical equipment such as switchboards and transformers from the viewpoint of weight reduction and cost reduction. - For boat fishing, a copper terminal is welded to the tip of an aluminum conductor, and the copper terminals are overlapped and bolted together to avoid an increase in contact resistance between the terminals and to facilitate handling. ing.

There are cold welding, hot welding, friction welding, explosion welding, etc. for joining aluminum and copper materials, but hot welding is suitable because the shape of the materials to be joined is not restricted to a specific shape. .

When joining aluminum and copper materials by hot pressure welding, from the viewpoint of ensuring the quality of the tensile strength and bending strength of the joint,
Minimizing the brittle alloy layer that inevitably forms at the bond boundaries in this type of bonding is of paramount importance.

Based on these technical requirements, conventional hot welding
A two-stage pressurization method is adopted in which the electrical heating is controlled by the amount of deformation of the joint, and strong pressure is further applied. Note that the joint ends of the aluminum material and the copper material are butted together in a so-called unprocessed state where the end face shape does not change.

[Problem to be solved by the invention]

By the way, with the method described above, sufficient quality assurance cannot be obtained due to variations in the strength stability of the joint part, and in practical terms, the strength can be guaranteed by increasing the rejection rate of the alloy layer by repeating deformation and pressure. The current situation is that we are getting it.

This results in an increase in the number of man-hours, complication of work, and an increase in manufacturing costs.

Therefore, an object of the present invention is to provide a method for hot-pressure welding of aluminum and copper materials, which can obtain stable strength of the joint with the same amount of work as the original basic hot-pressure welding.

[Means to solve the problem]

This invention was created to achieve the above object,
The feature is that the joint end is made of aluminum material with a bevel angle of 15 mm.
The purpose is to butt copper materials with convex shapes of 45° to 45° and apply electrical heating and strong pressure.

[For production]

According to this invention, the aluminum material and the copper material are brought into contact with their joining end surfaces and heated with electricity. When electrical heating is performed, the temperature rise concentrates on the joint surface due to the convex shape of the copper material, promoting deformation of the aluminum material with a low melting point, and
The fluidity of aluminum material is increased.

Further, the groove shape of the copper material allows smooth extrusion of the alloy layer and increases the bonding area. Strong pressure promotes extrusion of the alloy layer and completes the bonding.

[Example] FIGS. 1 and 2 show an embodiment of the present invention.

As the material to be joined, for example, a round bar-shaped aluminum material 2,
Similarly, a round rod-shaped copper material 4 is selected.

The joining end portion 6 of the aluminum material 2 can be made into an unprocessed shape having, for example, a flat joining surface 6a having the same diameter as the other portion.

The joint end 10 of the copper material 4 is formed into a substantially frustoconical convex shape with a groove angle θ, and has a tapered joint surface 10a, and a flat joint surface with a small area at the tip. 1
It has 0b. The groove angle θ is set in a range of 15° to 45°.

First, as shown in FIG. 2(A), the aluminum material 2 and the copper material 4 are butted together with their joint surfaces 6a and 10b in contact with each other. In this state, electrical heating is performed. When electrical heating is performed, as shown in FIG. 2B, the temperature rise is concentrated due to the convex shape of the joint end 10 of the copper material 4, and the aluminum material 2 melts corresponding to the small joint surface 10b. The transformation progresses incredibly quickly.

Subsequently, pressure deformation due to electrical heating progresses, as shown in the same figure (C
), the fluidity of the aluminum material 2 is promoted by the convex shape of the copper material 4, and the aluminum material 2 moves smoothly on the tapered joint surface 10a. By promoting the fluidity of the aluminum material 2, extrusion of the aluminum material 2 itself and the alloy layer 14 generated at the boundary become smooth.

Subsequently, as shown in FIG. 3(D), strong pressure is applied. As a result, strong adhesion between the aluminum material 2 and the copper material 4 is obtained, and the alloy layer 14 is extruded appropriately. Due to the convex shape of the copper material 4 created by the groove processing, the bonding area is increased compared to the bonding of flat bonding surfaces, thereby increasing the bonding strength. Further, since the aluminum material 2 is shaped to surround the outer surface of the joint end portion 10 of the copper material 4, the bending strength is increased. In addition, the same figure (E) shows the state in which paris is removed after strong pressurization.

Next, Table 1 is an example of experimental results showing changes in tensile strength in accordance with changes in groove angle θ and presence/absence of groove processing in aluminum material 2 and copper material 4. Note that 16φ round bar materials were used as the aluminum material 2 and the copper material 4.

Table 1 Table 2 is an example of the measurement results of the strength by electrical heating and the strength after strong pressurization, that is, after hot pressure welding, under the same conditions as above.

Table 2 According to the conventional method in which a 16φ round bar material is used as the material to be joined and hot welding is performed without beveling both parts, the tensile strength is approximately 1750 kg, as shown in Table 2. , copper material 4
As is clear from Table 12, when beveling is applied to
It is possible to increase the tensile strength. Also, the groove angle θ
The most desirable value is around 30''; in this region, beveling is not limited to only the copper material 4, but can also be applied to both or only the aluminum material 2 to increase the tensile strength compared to the conventional method. be able to.

Next, FIGS. 3 and 4 show another example, in which rectangular plates are joined together.

Similar to the above example, the joining end portion 18 of the aluminum material 16 has an unprocessed shape with a flat joining surface 18a. On the other hand, the joint end 22 of the copper material 20 has a groove angle θ, (θ1=15
It is formed into a convex shape with a trapezoidal cross section at an angle of 45° to 45°, and is substantially composed of upper and lower sloped joining surfaces 22a and 22b, and a flat joining surface 22c at the tip. In this example as well, the same bonding process as in the above example can be obtained. Table 3 shows experimental results showing the tensile strength and bendability of the joint between the aluminum material 16 and the copper material 20. Note that the dimensions of the aluminum material 16 and the copper material 20 are
This is the case when h=6 meters and w=40 meters.

Table 3 As is clear from Table 3, by beveling the copper material 20 when joining rectangular materials, the tensile strength can be increased compared to the conventional method, and the bending strength can also be increased. can be achieved.

〔Effect of the invention〕

According to this invention, the joining end of the copper material has a bevel angle of 15° to 4°.
By creating a 5° convex shape, it is possible to increase the tensile strength and bending strength in the basic hot welding process of electrical heating and strong pressure, thereby improving workability. , it is possible to improve the strength stability and reliability of the joint.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the hot press welding method for aluminum and copper materials according to the present invention, Fig. 2 is a schematic sectional view showing the same press welding process, and Fig. 3 is a perspective view showing another example. 4 are schematic cross-sectional views showing the butted state. 2.16...Aluminum material 4.20...Copper material 10.22...Joining end θ, θ1...Bevel angle Patent applicant Hakusan Seisakusho Co., Ltd. Representative Patent attorney Yoshi 1) Yoshiharu Figure 2

Claims (1)

[Claims] A hot pressure welding method for aluminum and copper materials in which a convex copper material with a bevel angle of 15° to 45° is butted against an aluminum material, and electrical heating and strong pressure are applied.