JPH02145214A - Electricity discharge machining electrode wire - Google Patents

Abstract

PURPOSE:To improve an electricity discharge quality and heighten its machining speed and reduce the number of wire snapping, by forming an electricity discharge machining electrode wire out of tungsten alloy containing at least 0.001 - 1.0 weight % of Re. CONSTITUTION:An electricity discharge machining electrode wire is formed out of tungsten alloy which contains at least 0.001 - 1.0 weight % of Re, and the remaining % of which is tungsten and unavoidable impurities. As a result, an electric current flows easily at this electric wire, and the quality of electricity discharge thereof is heightened. As a result, a spark can be generated smoothly, and a machining speed and the section precision of a machined matter can be improved, and the number of the snapping of the electricity discharge machining electrode wire can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrode wire for electric discharge machining, and particularly to an electrode wire for wire electric discharge machining that has excellent electric discharge machinability.

[Prior Art] Wire electrical discharge machining is an indispensable technology for precision machining of molds. In this machining method, a wire pulled with a predetermined force is moved in a direction intersecting the workpiece, causing a spark discharge between the wire and the workpiece, while simultaneously moving the workpiece according to the desired shape. .

Conventionally, brass wires have generally been used as electrode wires for wire electrical discharge machining (hereinafter referred to as cut wires).

However, it is desirable that the cut wire has the following characteristics. (1) The processing speed can be increased. (2) No deposits should be generated. (3) Good processing accuracy. (4) Excellent straightness (that is, the cut wire does not twist or curl, improving processing accuracy and reducing cut wire breakage). (5) The outer diameter of the cut wire has excellent roundness (as a result, the processing accuracy is improved).

(6) High tensile strength (as a result, the cut wire can be prevented from breaking). (7) Characteristics include having electrical conductivity. Pure tungsten is selected as the material for the cut wire because it satisfies these characteristics.

Pure tungsten has a tensile strength that is approximately three times that of brass, which is a typical example of its mechanical properties.

Therefore, the diameter of the cut wire using pure tungsten can be reduced. Therefore, using pure tungsten cut wire enables finer processing.

[Problems to be solved by the invention] However, pure tungsten cut wire has (1) poor discharge properties, so when pure tungsten cut wire is used,
Sparks do not occur smoothly. As a result, the machining speed slows down and the precision of the cut surface of the workpiece deteriorates. Moreover, the number of disconnections of the cut wire increases.

Furthermore, since pure tungsten cut wire (2) has low tensile strength at high temperatures, the cut wire becomes distorted at high temperatures. As a result, there have been drawbacks such as poor cutting surface accuracy of the workpiece.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cut wire that can improve processing speed, improve the precision of the cut surface of a workpiece, and reduce the number of times the cut wire breaks.

[Means for Solving the Problems] The electrode wire for electrical discharge machining according to the present invention is made of a tungsten alloy containing at least 0.001 to 1.0% by weight of Re, with the remainder being tungsten and inevitable impurities. Become.

[Operations and effects of the invention] The tungsten alloy containing Re in tungsten has the following properties:
It has the effect of making it easier for electrons to jump out, that is, it has an emission effect. Therefore, current can easily flow through the cut wire made of the tungsten alloy, and its discharge performance is improved. As a result, when a cut wire made of the above tungsten alloy is used, sparks are generated smoothly.

Therefore, it is possible to improve the processing speed, improve the precision of the cut surface of the workpiece, and reduce the number of times the cut wire breaks.

In this invention, the content of Re is 0°001 in weight ratio.
The reason why the content is limited to 1.0% by weight is that if it is less than 0.001%, the emission effect will hardly occur and the discharge performance will not improve much. - On the other hand, if it exceeds 1.0%, the cut wire becomes brittle and the number of disconnections of the cut wire increases.

Furthermore, in a tungsten alloy containing Re in tungsten, the recrystallization temperature of the tungsten alloy increases because fine particles of Re are uniformly dispersed in the tungsten. This improves the high temperature tensile strength of the tungsten alloy.

Therefore, even if the cut wire becomes hot during wire electrical discharge machining, the distortion of the cut wire will be reduced.
The precision of the cut surface of the workpiece is improved.

Furthermore, the tungsten alloy has higher tensile strength than pure tungsten. Therefore, when the above tungsten alloy is used, a cut wire with a smaller outer diameter can be manufactured. Therefore, it becomes possible to process minute workpieces.

[Example] Re 0.0010.0.0100.0.10 respectively
A cut wire made of a tungsten alloy containing 0.00.1.0.1.5% by weight was produced by the following method.

Commercially available 99.99% pure tungsten powder (
Re powder (average particle size 3-5 μm) and Re powder (average particle size 1-2 μm)
) to prepare an alloy powder.

Next, the alloy powder was compressed using a mold press at a pressure of 3 tons/cm2 to produce a square rod-shaped powder molded body.

Further, the powder compact was pre-sintered in a hydrogen gas atmosphere at about 1200°C.

The pre-sintered powder molded body was directly sintered with electricity in a hydrogen gas atmosphere at about 3000° C. to produce an ingot.

The ingot was repeatedly subjected to rolling, heat treatment, rolling, wire drawing, heat treatment, and wire drawing to produce a cut wire with a wire diameter of 50 μm made of a tungsten alloy from which graphite had been removed by electrolytic treatment.

Using each of the tungsten alloy cut wires thus obtained, the following tests and (1) constant were conducted.

(1) Tensile test at each temperature (Table 1).

The pulling speed was 0.1 mm/min.

(2) Machining speed during electrical discharge machining, surface roughness of the workpiece, and nj constant of the number of wire breaks (Table 2).

Measurement (2) was performed using a commercially available wire electrical discharge machine. The electrical discharge machining conditions are shown in Table 3.

For comparison, using a tungsten alloy cut wire containing 1.5% by weight of Re and a commercially available pure tungsten cut wire, the above (1) and (2)
) were tested and measured.

The results are shown in Tables 1 and 2. The results of the tensile test are also shown in FIG.

(Left below) According to Table 1, if tungsten contains 0.0010% by weight or more of Re, the tensile strength at each temperature will be
It can be seen that the Re content increases as the Re content increases.

According to Table 2, if tungsten contains 0.0010% by weight of Re, the cutting speed during electrical discharge machining and the surface roughness of the workpiece increase and decrease, respectively, as the Re content increases. I understand that.

It can be seen that the number of disconnections increases significantly when the Re content in tungsten is outside the range of 0.0010% by weight to 1.0% by weight.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the tensile test results of Examples. Patent applicant Sumitomo Electric Industries, Ltd.Test temperature ("C) Re1.5 So.

Claims (1)

[Claims] An electrode wire for electric discharge machining made of a tungsten alloy containing at least 0.001 to 1.0% by weight of Re, the remainder being tungsten and inevitable impurities.