JPH0683905B2 - Electrode material for resistance welding - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrode material for resistance welding.

(Background Art) In recent years, spot welding with high productivity has come to be frequently used for joining mild steel sheets and galvanized steel sheets in the automobile industry, for example, and the conventional electrode material used for such welding is Cu. -Cr alloy, Cu-Cr-Zr alloy, Cu-Be-Co alloy, etc. have been used.

Such a welding electrode requires a large current during welding,
Further, since it is continuously used, there is a problem that the temperature becomes high and the tip portion is cracked, deformed, or easily worn.

Therefore, the general characteristics required as a welding electrode material used in resistance welding such as spot welding and seam welding are as follows.

Good electrical and thermal conductivity: As mentioned above, it is necessary to pass a large current through the electrode, so there is not much heat generation due to electrical resistance, and the heat generated must be quickly conducted and cooled. .

Deformation resistance: In spot welding, a strong compressive stress is applied to the tip of the electrode during welding, so mechanical strength at high temperatures of 500 ° C or higher and at room temperature is required. When the tip of the electrode is deformed or cracks are generated, it is difficult to apply sufficient stress to the welded portion uniformly, which adversely affects the weld strength and the appearance of the welded portion.

No welding: When the electrode material and the material to be welded are easily alloyed, the material to be welded is likely to be welded to the tip of the electrode, but since welding interferes with welding, it is desirable that there is no welding. .

Ease of manufacture and price: It is desired that the alloy itself be easy to manufacture, that it has excellent workability for welding electrodes, and that it is a low price as a consumable item.

Conventionally used Cu-Cr alloys, Cu-Cr-Zr alloys, Cu-Be-Co alloys, etc. have been insufficient in the following points in view of the above-mentioned required characteristics.

That is, Cu-Cr alloys and Cu-Cr-Zr alloys have high conductivity and are also excellent in terms of softening resistance and hardness at high temperatures, but they are hardened at a high temperature of about 1000 ° C during manufacturing. Therefore, in this case, the crystal grains may become coarse and deformation resistance may not be excellent, and these alloys are likely to cause cracks at the tips when used as an electrode, and the present inventors have caused this by the presence of Cr. It was found to be encouraged.

Although Cu-Be-Co alloy has high strength at room temperature, it has low electrical and thermal conductivity, easily generates heat during use, does not have excellent softening resistance, and is expensive, but is preferable as an electrode material. Was not.

Other materials such as W and Mo, which have higher high-temperature strength, are also conceivable, but other necessary condition as an electrode, that is, high electrical conductivity is impaired, and the electrode itself causes abnormal heat generation due to its specific resistance or lower toughness. It was difficult to put into practical use due to cracking and damage.

Further, a welding electrode having a coating layer of nitride, carbide or carbonitride on the surface of a copper alloy in which oxide is dispersed (Japanese Patent Laid-Open No. 58-14187).
No. 6) has been proposed, but this is because the electrical conductivity of the surface layer is small and the heat generated at the tip is large, so that the copper alloy that is the base material is prone to softening, deformation, and melting, and its life is not sufficient. It was

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, has excellent electrical and thermal conductivity, is difficult to weld when used as a welding electrode, and generates extra heat at the electrode tip. Is less
It is intended to provide an electrode material for resistance welding in which the electrode is less worn, the adhesion of the surface coating layer is good, and which is easy to manufacture.

The present invention is, on a copper alloy, Ni, Co, Cr, Mo or an intermediate coating layer made of an alloy thereof, and a metal or particles in which oxide, carbide, nitride or carbonitride particles are dispersed thereon. An electrode material for resistance welding, comprising a surface coating layer made of an alloy (hereinafter referred to as a dispersion type alloy).

In the present invention, as the copper alloy as the base material, based on copper, an alloy obtained by adding a metal such as Cr, Zr, Be, Co, Mo (eg, Cu-Cr, Cu-Cr-Zr, Cu -Be-Co, Cu-Zr-Fe-P alloy, etc.),
Examples include dispersion-strengthened copper alloys in which oxides such as Al ₂ O ₃ are dispersed.

Further, the dispersion type alloy constituting the surface coating layer is a metal or an alloy,
For example, Co, Cr, W, Mo, Co, Ni etc. or their alloys (eg Ni-C
(r alloy etc.), etc., with oxides, carbides,
It is a dispersion of particles of a nitride or carbonitride, for example, chromium carbide, tungsten carbide, titanium carbide, silicon carbide, aluminum oxide, titanium nitride, tantalum nitride, titanium carbonitride, and the like.

This surface coating layer is an oxide, a carbide that is dispersed even if the base metal or alloy of the dispersion type alloy disappears during welding,
Since the particles of nitride or carbonitride remain and accumulate on the surface with good adhesion, they are difficult to weld, and the coating thickness is preferably 5 to 100 μm. If it is less than 5 μm, the anti-welding effect is small, and if it exceeds 100 μm, the industrial cost becomes high and the heat generation at the electrode tip becomes large.

The first purpose of the intermediate coating layer is to improve the adhesion between the copper alloy of the base material and the surface coating layer, and to prevent peeling due to thermal stress. The coating layer preferably has a thickness of 0.5 to 100 .mu., And if it is less than 0.5 .mu.

In order to improve the adhesion between the base copper alloy and the intermediate coating layer, C
A base layer of u, Ni or the like may be provided.

Hereinafter, the present invention will be described by way of examples with reference to the drawings. 1 to 5 are vertical sectional views showing an electrode chip which is an embodiment of the present invention. In the figure, 1 is a copper alloy that constitutes the chip body, 3 is the tip of the electrode, and 1'shown in FIG. 4 is the chip body, and the copper alloy 2 (eg, carbon fiber reinforced copper Alloys, etc.) are joined.

Reference numeral 4 is an intermediate coating layer made of Ni, Co, Cr, Mo or an alloy thereof, and 5 is a surface coating layer made of the dispersion type alloy as described above.

In FIG. 1, the intermediate coating layer 4 and the surface coating layer 5 are coated on the tip 3 of the copper alloy 1.

In FIG. 2, the intermediate coating layer 4 and the surface coating layer 5 are coated on the entire surface of the copper alloy 1.

In FIG. 3, the entire surface of the copper alloy 1 is coated with the copper coating layer 6 by electroplating, and the surface of the tip 3 thereof is coated with the intermediate coating layer 4 and the surface coating layer 5.

In FIG. 4, the intermediate coating layer 4 and the surface coating layer 5 are coated on the surface of the copper alloy 2 at the center of the chip 1 '.

FIG. 5 shows a tip for spot welding in which the tip 3 of the copper alloy 1 is coated with the intermediate coating layer 4 and the surface coating layer 5.

To coat the dispersed alloy of the surface coating layer, electroplating,
A method such as electroless plating or vapor deposition is used. For example N
Particles of a dispersion compound are dispersed in a plating solution such as i, Co or Cr and electroplating is performed.

(Example) An electrode tip body for welding as shown in FIG. 1 was prepared from the base material alloy shown in Table 1, and the intermediate coating layer 4 and the surface coating layer were formed on the tip 3 thereof as shown in Table 1. 5 was coated under various conditions. As the coating method, electroplating (A), sputtering (B), ion plating (C) and activation reaction vapor deposition (D) were used.

The electrodes had a diameter of 16 mm at the parallel part and a diameter of 8 mm at the tip.

0.8 mm thick with the obtained electrode tip for spot welding
2 sheets of zinc-plated iron plate of
Table 1 shows the results of measuring the number of spots until welding occurs on the electrode by spot welding under the conditions of current 10 kA, pressure 200 kg and welding time 25 cycles.

From Table 1, it can be seen that Nos. 1 to 6 according to the present invention have remarkably long life before welding occurs and no peeling occurs as compared with Comparative Examples and Conventional Examples. Nos. 7 and 8 of the comparative example caused peeling.

(Effects of the Invention) The resistance welding electrode material of the present invention configured as described above has the following effects.

(B) Since the electrode body is made of copper alloy, it has excellent electrical and thermal conductivity, and there is little abnormal heat generation during welding and brazing.

(B) Since the surface coating layer made of a metal or alloy in which oxide, carbide, nitride or carbonitride is dispersed is provided on the outermost surface, even if the metal or alloy in the dispersed alloy disappears during welding. Dispersed compound particles remain and accumulate on the surface with good adhesion,
Further, since the dispersion type alloy has good oxidation resistance, it is difficult to weld and the life is improved. In particular, it is difficult to weld even to a material to be welded coated with a low melting point metal or alloy such as Zn, Sn, solder, or Ag.

Also, since it is a dispersion type alloy, it has little wear.

(C) Since the intermediate coating layer made of Ni, Co, Cr, Mo or their alloys is provided on the copper alloy, the adhesion between the copper alloy and the surface coating layer is good and peeling does not occur.

(D) Since all the coating layers are thin and mainly consist of metal or alloy, there is no extra heat generation at the electrode tip.

(E) The structure is simple, and the surface coating layer can be manufactured easily by electroplating with a plating solution in which dispersed compound particles are dispersed, for example, and thus is easy to manufacture.

[Brief description of drawings]

1 to 5 are vertical sectional views showing an electrode chip which is an embodiment of the present invention. 1,2 …… Copper alloy, 1 ′ …… Chip body, 3 …… Tip, 4,
4 '... intermediate coating layer, 5 ... surface coating layer, 6 ... copper coating layer.

Claims (4)

[Claims] 1. A metal or an intermediate coating layer made of Ni, Co, Cr, Mo or an alloy thereof on a copper alloy, on which an oxide, carbide, nitride or carbonitride particle is dispersed. An electrode material for resistance welding comprising a surface coating layer made of an alloy. 2. The resistance welding electrode material according to claim 1, wherein the intermediate coating layer has a thickness of 0.5 to 100 .mu.m and the surface coating layer has a thickness of 5 to 100 .mu.m. 3. A metal or alloy in which oxide, carbide, nitride or carbonitride particles are dispersed is based on Co, Cr, W, Mo or their alloys. The electrode material for resistance welding according to item 2 or item 3. 4. The electrode material for resistance welding according to claim 1, 2 or 3, wherein the carbide is a carbide of Cr, W, Ti or Ta.