JPH07108388A - Manufacture of electrode tip for spot welding and electrode tip - Google Patents

Abstract

PURPOSE:To provide the manufactures of an electrode tip for spot welding and an electrode tip, by which an increase in the deformation of an electrode tip, can be prevented, and a weld quality and making the life of an electrode tip long, can be secured. CONSTITUTION:A first powder material A excellent in heat-resisting property and a second powder material B excellent in heat conductivity and electricity conductivity and with a grain distribution shifting to the grain distribution of the first powder material A, are supplied in an electrode tip forming die 1 to vibrate them. An electrode tip C is manufactured by arranging with a gradient for the grain size of electrode tip so that the abundance of the first powder material becomes larger as the first powder material moves on an electrode tip forming side 1a, and by pressurizing and sintering this powder material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding electrode tip and a method for manufacturing the electrode tip.

[0002]

2. Description of the Related Art An electrode tip for spot welding is disclosed in Japanese Patent Publication No.
As disclosed in JP-A-37825, an alumina dispersion-strengthened copper alloy is extruded, and a rod having a fibrous structure is cut into a predetermined size to form a chip material.
The chip material is manufactured by breaking the fibrous structure into a granular structure by cold or hot forging and cutting the chip material.

Further, as disclosed in Japanese Patent Publication No. 2-40428 and as shown in the sectional view of FIG. 5, a mounting base member 2a made of a light alloy material such as aluminum and a tip chip member 2b made of a copper alloy material are provided. There is proposed an electrode tip 2 for spot welding, which is composed of two members (1) and (2) and is integrally connected to both members 2 a and 2 b.

[0004]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 2-378
According to the electrode tip disclosed in Japanese Unexamined Patent Publication No. 25, the fibrous structure is destroyed and converted into a granular structure during cold or hot forging, so that it is generated along the fibrous structure due to impact at high temperature during welding. It is possible to prevent cracks. On the other hand, the electrode tip disclosed in Japanese Examined Patent Publication No. 2-40428 can be manufactured at low cost because it is a composite with a light alloy such as aluminum, and the product cost can be reduced.

However, since the tips of these conventional electrode tips are formed by cutting a copper alloy,
Particularly in spot welding of galvanized steel sheet, when the electrode is pressurized and resistance heating is performed, the melting point of zinc is lower than that of the base metal, so the molten zinc is picked up at the tip of the electrode tip made of copper alloy and the zinc component becomes It diffuses in and creates a Zn-Cu texture. Therefore, the resistance at the tip of the electrode tip increases, the amount of heat generation increases, the deformation of the tip diameter increases, the current density decreases, the required welding strength cannot be obtained, and the welding quality decreases and the life of the electrode tip decreases. There is a defect.

Further, as a measure for extending the life of the electrode tip, there is a case where a measure is taken to prevent the increase of the electrode tip by plating the tip of the electrode tip with a metal having high heat resistance to withstand the welding heat. The plating layer is easily removed by polishing the tip, etc., and there is a problem that it cannot be sufficiently used for a long time.

Therefore, an object of the present invention is to prevent an increase in deformation of the tip of the electrode tip, to obtain necessary welding strength, to secure stable welding quality and to prolong the life of the electrode tip. It is to provide a manufacturing method of.

[0008]

The electrode tip for spot welding of the present invention, which achieves the above-mentioned object, is a first electrode having relatively excellent heat resistance.
Is an electrode tip for spot welding, which is formed by sintering a mixture of the above powder material and a second powder material which is relatively excellent in thermal conductivity and electric conductivity. An abundance ratio of approximately 100% by weight and formed by sintering in such a manner that the abundance ratio becomes gradually smaller as it moves to the base end side, and gradually increases as the abundance ratio of the second powder material moves to the base end side. Is.

In addition, the method for manufacturing an electrode tip for spot welding according to the present invention comprises the first powder material having relatively high heat resistance and the first powder material having relatively high thermal conductivity and electrical conductivity. A second powder material having a particle size distribution that at least partially overlaps with the particle size distribution is supplied into the electrode tip forming die, and vibration is applied to the electrode tip forming die to mix the powder material with the electrode tip. The existence ratio of the first powder material on the side of the tip of the electrode tip in the molding die is about 100.
Gradient arrangement is performed such that the weight percentage gradually decreases toward the base molding side and gradually increases as the abundance ratio of the second powder material shifts toward the base molding side, and the mixture in the inclined arrangement is pressed. It is a fired one.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electrode tip for spot welding and the electrode tip according to the present invention will be described below.

First, as shown in FIG. 1, a first powder material A having a relatively high heat resistance, for example, a Ni--Cr alloy powder, and a second powder having a relatively high thermal conductivity and electrical conductivity. A material B, for example, Cu-Cr alloy powder is prepared.

In this case, Table 1 shows the distribution ratio (% by weight) of the first and second powder materials A and B in each particle size range, and FIG. 2 shows the particle size distribution a and the first particle size distribution of the first powder material A. Two
As shown in the particle size distribution b of the powder material B, the particle size distribution a and the particle size distribution b of the powder materials A and B partially overlap each other, and the particle size distribution a of the first powder material A is ,
The first powder material A and the second powder material B are intentionally prepared so that the particle size distribution b of the second powder material B is displaced toward the relatively large particle size side (particle size adjusting step 101).

[0013]

[Table 1]

Next, as shown in FIG. 1, the first powder material A
And the second powder material B are mixed and supplied into the electrode tip molding die 1 (material filling step 102), and the electrode tip molding die 1
Vibration is applied to the electrode tip molding die 1 in a state where the electrode tip tip molding side 1a is positioned downward (vibration applying step 10
3).

When vibration is applied to the electrode tip mold 1 in the vibration applying step 103, the first powder material A and the second powder material B have the same specific gravity of the particles, so that the powder material A and the powder material A have the same specific gravity. In the mixture with B, particles having a small diameter are distributed on the lower portion of the electrode tip molding die 1, that is, the electrode tip tip molding side 1a, and the upper portion, that is, the electrode tip base molding side 1a.
Particles having a large diameter are distributed in b, and the powder materials A and B are provided with different particle size distributions. As a result, the electrode tip tip forming side 1 in the electrode tip forming die 1 is
The abundance ratios of the powder materials A and B are continuously inclined from a to the electrode tip base molding side 1b.

A first powder material A which is continuously inclined and arranged.
As shown in FIG. 3, the abundance ratio of the first powder material A to the second powder material B and the second powder material B is about 100% by weight on the electrode chip tip molding side 1a in the electrode chip mold 1, and the base molding is performed. Side 1
It gradually becomes smaller as it shifts to b, and following this, the abundance ratio of the second powder material B gradually increases and the base molding side 1
In b, the abundance ratio of the second powder material B is 100% by weight.

The mixture of the first powder material A and the second powder material B, which is continuously inclined and arranged as described above by the vibration applying step 103, is stored in the electrode tip mold 1 in the next pressure molding step 104. Then, it is pressure-molded, and in the subsequent sintering step 105, the electrode chip material w is obtained by being held at a high temperature and sintered.

In the cutting step 106, the electrode tip material w is processed into the electrode tip C by cutting the outer peripheral portion wa such as the tip and the recess wb.

The electrode chip C manufactured in this way
Is the first range which is mainly excellent in heat resistance from the tip Ca to the predetermined range a.
Is formed by sintering the powder material A, while the predetermined range b from the base end Cb is mainly the second having excellent thermal conductivity and electrical conductivity.
The powder material B is molded by sintering, and the abundance ratio of each material is continuously changed in the range c located between the predetermined ranges a and b. In addition, the heat resistance of the electrode tip is ensured, the outer diameter of the electrode tip tip Ca is prevented from increasing, and the life of the electrode tip C is extended.

Furthermore, since the predetermined range a from the tip Ca is formed of a material having excellent heat resistance, a layer having sufficient heat resistance is maintained even when the tip Ca of the electrode tip C is polished, and the layer is maintained for a long time. It has the effect that it can be used for.

In the above description, the first powder material A and the second powder material B having a particle size distribution that is displaced toward a relatively large particle size side with respect to the particle size distribution of the first powder material A are described. The powder material A and B were supplied into the electrode chip mold 1, the electrode chip tip molding side 1a of the electrode chip mold 1 was positioned on the lower side, and vibration was applied to tilt the powder materials A and B. The particle size distribution of the second powder material B is displaced to a relatively small particle size side with respect to the particle size distribution of the powder material A, and the electrode tip tip molding side 1a of the electrode chip mold 1 is positioned on the upper side and vibrated. It is also possible to arrange the powder materials A and B in a slanted arrangement by providing the above.

In the above embodiment, the first powder material A having excellent heat resistance and the second powder material B having excellent thermal conductivity and electric conductivity were used. sex,
Arc resistance, using a powder material excellent in welding resistance, by the same method as described above, by manufacturing an electrode chip,
Further, the consumption of the electrode tip can be reduced, the life of the electrode tip can be further extended, and an electrode tip with stable welding quality can be obtained.

Specifically, for example, W-Cu alloy powder is used as the first powder material A, and Cu is used as the second powder material B.
-Prepare Cr-based alloy powder. The particle size distributions of the powder materials A and B are adjusted so that they partially overlap each other and the particle size distributions are displaced from each other.

A mixture of the first powder material A and the second powder material B is supplied into the electrode tip mold 1, and the electrode tip mold 1 is vibrated to produce the powder material A,
The mixture of B was inclined and arranged so that the abundance ratio of the first powder material A gradually became smaller as the abundance ratio of the first powder material A moved from the electrode tip front end molding 1a side to the base end molding side 1b in the electrode tip molding die 1, and this powder material was added. It is pressed to obtain an electrode tip material.

Next, an electrode chip C is obtained by cutting a necessary portion such as the outer circumference of the electrode chip material w.

Electrode chip C manufactured in this way
Is configured such that the tip is formed mainly of the first powder material excellent in heat resistance, arc resistance and welding resistance, and the abundance ratio of the first powder material gradually decreases as it moves to the base end. Therefore, the arc resistance is further excellent, and the life of the electrode tip can be further extended.

This is, for example, the first in the present embodiment.
Of the W-Cu alloy powder as an example of the powder material A, the consumption amount by the arc of the sintered gold is changed as shown in FIG. 4 due to the change of the content (% by weight) of the tungsten W with respect to the copper Cu. It is known that, for example, the consumption of copper Cu by the arc is about 1.6 cm ³ / KA-S.
On the other hand, it can be understood from the fact that the consumed amount of the sintered gold containing 60% by weight of tungsten W by the arc is about 0.3 cm ³ / KA-S.

In the above description, W-Cu alloy powder is used as an example of the first powder material, and Cu-C is used as the second powder material.
Although the r-based alloy powder is used, other alloy powder having the same function can be appropriately used.

[0029]

EFFECT OF THE INVENTION According to the spot welding electrode tip and the method of manufacturing the electrode tip of the present invention, the tip of the welding electrode tip is mainly made of a material having excellent heat resistance, heat resistance, arc resistance and welding resistance. It is made of a different material, and is configured to sequentially migrate to a material with excellent thermal and electrical conductivity that migrates from the distal end to the proximal end, so that the electrical conductivity and thermal conductivity of the welding electrode tip can be improved. While maintaining
The deformation of the tip of the electrode tip is prevented from increasing, the required welding strength is obtained, stable welding quality and long life of the electrode tip can be secured, and further heat resistance or arc resistance at the tip,
Since a relatively thick layer with excellent welding resistance is formed, sufficient heat resistance can be ensured even for polishing the tip, and stable welding strength and welding quality can be maintained. Have.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of an electrode tip for spot welding and a method for manufacturing the electrode tip according to the present invention.

FIG. 2 is an explanatory diagram of particle size distributions of a first powder material and a second powder material in this example.

FIG. 3 is likewise an explanatory view of the manufacturing method of the electrode chip of the present embodiment.

FIG. 4 is an explanatory diagram of utilization of Cu—W-based sintered bond gold by arc consumption.

FIG. 5 is an explanatory diagram of a conventional electrode tip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode tip molding die 1a Electrode tip tip molding side 1b Electrode tip base molding side A First powder material B Second powder material C Electrode tip Ca tip Cb Base edge

Claims (4)

[Claims] 1. An electrode tip for spot welding, which is obtained by sintering a mixture of a first powder material having relatively high heat resistance and a second powder material having relatively high thermal conductivity and electric conductivity. Therefore, the abundance ratio of the first powder material at the tip of the electrode tip is approximately 100% by weight, and the abundance ratio of the second powder material gradually shifts to the base end side as it moves to the base end side. An electrode tip for spot welding, characterized in that the electrode tip is inclined and arranged so as to become larger in accordance with the above, and is sintered. 2. The electrode tip for spot welding according to claim 1, wherein the first powder material is relatively excellent in heat resistance, arc resistance and welding resistance. 3. A particle size that is relatively excellent in heat conductivity and electrical conductivity with the first powder material that is relatively excellent in heat resistance, and that is displaced at least partially overlapping the particle size distribution of the first powder material. The second powder material having a distribution is supplied into the electrode tip mold, and the electrode tip mold is vibrated to mix the powder material with the second powder material in the electrode tip mold at the electrode tip tip molding side. The existence ratio of the powder material of 1 is about 1
It gradually decreases as it moves to the base molding side at 00% by weight,
A method for manufacturing an electrode tip for spot welding, characterized in that the second powder material is inclinedly arranged so that the abundance rate of the second powder material gradually increases as it moves to the base end molding side, and the mixture in the inclined arrangement is pressure-sintered. . 4. The method for manufacturing an electrode tip for spot welding according to claim 3, wherein the first powder material is relatively excellent in heat resistance, arc resistance and welding resistance.