JPS60135504A - Sintered composite body - Google Patents

Abstract

PURPOSE:To obtain a sintered composite body which has high reliability of joining between a sintered body infiltered with an infiltering material and a base material and can prevent failure of the sintered body with a composite electrode or the like consisting of the sintered body and the base material by fitting the base material to the sintered body. CONSTITUTION:An infiltering material layer 3 formed by partial leaching of the infiltering material infiltered into an annular sintered body 1 infiltered with the infiltering material exists in the inside circumferential surface of the sintered body 1. A base material 2 is press-fitted into the hollow part on the inside of the body 1 with the outside circumferential part thereof in contact with the layer 3. The material 2 is thus securely joined to the body 1. Since the layer 3 is soft, the layer 3 accepts the material 2 and can be press-fitted to the body 1 even if the material 2 is inclined slightly with respect to the body 1. A considerable oversize in the fitting between the body 1 and the material 2 is absorbed by the layer 3 and therefore the press-fitting of the material 2 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sintered composite formed by fitting a base material into a sintered body.

[Technical background of the invention and its problems]

BACKGROUND ART Some electrodes used for welding electrical parts, electric discharge machining, etc. are disk-shaped and are rotated by a rotating shaft while contacting conductive terminals to conduct electricity. This electrode uses a composite electrode in which only the outer periphery is made of electrode material to reduce costs. For example, an annular sintered body made of a high-melting point metal such as tungsten is infiltrated with a conductive metal such as copper or silver to make an electrode material, and an easy-to-process base material such as iron is placed in the hollow inside of this sintered body. The two are joined together using silver solder or other brazing.

However, this composite electrode has a problem of low bonding reliability due to brazing between the sintered body and the base material.

The inventor focused on this point and, as a result of repeated research, came up with the following knowledge.

In other words, during brazing, the sintered body and base material are sometimes heated;
In this case, the base material expands more than the sintered body due to the difference in coefficient of thermal expansion between the two. Taking this into consideration, conventionally the gap between the two is kept large, but for this reason, the base material oxidizes due to the heat of brazing, and the brazing between the sintered body and the molten material is difficult. It is thought that pinholes are formed in the area, resulting in poor electrical continuity between the two.

In addition, if the gap between the sintered body and the melted material is made small in order to prevent the above-mentioned difficulties, brazing can sometimes cause damage to the sintered body due to thermal expansion of the base material. .

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and it is an object of the present invention to provide a sintered composite that has high bonding reliability between a sintered body and a base material and can prevent damage to the sintered body.

[Summary of the invention]

The sintered composite of the present invention includes a sintered body infiltrated with an infiltrating material, and a base plate fitted onto the sintered body without using a bonding material.

For example, the base material is press-fitted inside the sintered body and joined without using brazing. In this case, the fit between the sintered body and the base material is an interference fit, and the outer diameter dimension of the base material is set larger than the inner diameter dimension of the sintered body.

In the sintered composite of the present invention, one of the embodiments in which the base material is formed into a sintered body is shown in FIG. That is, in the figure, I is an annular sintered body infiltrated with an infiltrating material, and 2 is a base material having a shape corresponding to the inner hollow part of the sintered body I. An infiltrant layer 3 is present on the inner circumference of the sintered body I, which is formed by a part of the infiltrant infiltrated into the sintered body I. The base material 2 is press-fitted into the inner hollow part of the sintered body I with its outer circumferential portion in contact with the infiltrant layer 3.

Therefore, the base material 2 is firmly joined to the sintered body I. Since the infiltration material layer 3 is soft, the base material 2 is the sintered body I.
The infiltrant layer 3 can receive the base material 2 and be press-fitted into the sintered body I even if the base material 2 is tilted to some extent. Furthermore, even if the fitting dimension between the sintered body I and the base material 2 is quite large, the flexible infiltrant material I-3 absorbs this amount, so that the base material 2 is Can be press-fitted into.

Furthermore, if the combination of the base material 2 and the infiltrant layer 3 is the same,
Even when the material of the sintered body I is different, since the material of the fitting portion is always constant, the tolerance of the fit between the sintered body I and the base material 2 can be made constant.

In addition, when using the infiltrant layer as described above, the infiltrant layer 3
The thickness is preferably 0.5 mm or more.

In the sintered composite of the present invention, another form in which the base material is press-fitted into the sintered body is as shown in FIG. The outer periphery of the material 2 is press-fitted into the sintered body I by bringing it into direct contact with the inner periphery. in this case,
The bonding strength between the base material 2 and the sintered body I is increased.

When producing the sintered composite of the present invention, the sintered body and the base material are manufactured separately, and the sintered body in which the two are then assembled is subjected to an E-finishing process after being infiltrated.

In the case of the embodiment shown in FIG. 1, the surplus of the infiltrant material leached onto the surface of the sintered body is left in the inner circumference of the sintered body.

The materials of the sintered body, infiltration material, and base material in the sintered composite of the present invention can be variously combined depending on the application. When used as an electrode for welding or electrical discharge machining, a sintered body mainly made of tungsten is infiltrated with copper or silver, and the electrode material and the base material are made of iron, copper, brass, or the like.

The sintered composite of the present invention can be used for various purposes, and is particularly suitable for use as an electrode for welding or electrical discharge machining. For example, when used as a welding electrode, the rotating shaft 4 is fixed at the center of the base material 2 as shown in FIG. 5 and turn on the power. Welding is performed using the outer circumference of the sintered body I.

[Embodiments of the invention]

A case of manufacturing an electrode will be described as an example of the present invention.

After pressurizing the tungsten powder at a pressure of about 3 tons/d, the tungsten powder was sintered at a temperature of about 1200° C. for about 60 minutes to form a ring-shaped sintered body. This sintered body was infiltrated with copper at a temperature of about 1200° C. for about 60 minutes. This sintered body was made into an outer diameter of 100 u x an inner diameter of 90 x with a copper layer of about 2 U thick left on the inner periphery.
Finished with a thickness of 5IIJ. Further, an iron material with a thickness of about 6 square meters was processed into a disk shape with a diameter of 90.05+llJ. Then, the iron material was press-fitted into the inside of the sintered body using a press. In this case, the diameter of the iron material can be determined as appropriate within a range that does not damage the annular sintered body. When used as a welding electrode as shown in FIG. 3, the sintered body and the iron material were tightly bonded and the electrical continuity between them was good. The welding electrode obtained in this way uses a sintered body of high-melting point metal and a induction machine infiltrated into it, so the electrode wear is low and the outer periphery of the rotating body can be used evenly. Because it is welded, it can withstand long-term use.

〔Effect of the invention〕

As explained above, according to the present invention, the base material is mechanically joined to the sintered body without brazing. It is possible to obtain a sintered composite in which the base material and the sintered material are easily and reliably joined without causing the problem of breakage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one form of press-fitting of the base material in the sintered composite of the present invention, FIG. 2 is a sectional view showing another form of press-fitting,
FIG. 3 is an explanatory diagram showing a case where the sintered composite is used as an electrode. ! ... Sintered body, 2... Base material, 3... Infiltration material layer.

Claims (4)

[Claims] (1) A sintered composite comprising a sintered body infiltrated with an infiltrant and a base material fitted onto the sintered body. (2) The sintered composite according to claim 1, wherein an infiltrant is present between the substrate, the material, and the sintered body. (3) The sintered composite according to claim 1, wherein the base material and the sintered body are in direct contact with each other. (4) The sintered composite according to claim 1, wherein the sintered body is mainly made of tungsten and is infiltrated with an infiltrant made of a conductive metal.