JPH0261076A - Production of electrode wire for electric discharge machining - Google Patents

Abstract

PURPOSE:To produce an electrode wire for electric discharge machining having high strength, not causing breaking during use and ensuring a high machining rate by immersing a metal wire coated with Cu, Zn or a Cu-Zn alloy in an aq. soln. contg. sulfuric acid and hydrogen peroxide to oxidize the coating layer and by drawing the wire as required. CONSTITUTION:A wire of a metal such as Cu, a Cu alloy, steel, stainless steel, W or Mo as a core wire is coated with Cu, Zn or a Cu-Zn alloy and immersed in an aq. soln. contg. 0.5-20vol.% sulfuric acid and 1-40vol.% hydrogen peroxide to form a Cu, Zn or Cu-Zn oxide coating film on the surface of the wire. This wire is drawn at >=10% reduction of area as required. An electrode wire for electric discharge machining not causing jamming or breaking during use because of the smooth oxide coating film and ensuring a high machining rate is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an electrode wire for electric discharge machining, which can particularly improve the machining speed in wire cut electric discharge machining.

[Conventional technology and its issues]

In wire-cut electrical discharge machining, electrode wires for electrical discharge machining are placed opposite to the workpiece, and a pulse discharge is generated between them, and the workpiece is machined by the heat and impact caused by the discharge, making it possible to create complex-shaped press molds, etc. This is a method of manufacturing with high precision.

Various materials have been proposed for electrodes for wire-cut electrical discharge machining, including copper, which is easy to obtain and economical for boat fishing, and is easy to process into thin wires of 0.511 Im or less. Alternatively, copper alloys such as brass are often used.

In the above machining, water is generally used as the machining fluid, and an electrolytic current flows through this machining fluid. This electrolytic current reduces the machining energy due to electric discharge and becomes one of the major factors that reduce the machining speed.

For this reason, several methods have been proposed to reduce such electrolytic current. For example, JP-A-58-
As disclosed in Japanese Patent No. 4317, there is a proposal to coat the surface of a conductor with an insulating material to reduce electrolytic current during processing. However, with this method, the irregularities on the surface of the electrode wire become large, and the guide of the electrode wire in the wire cut processing machine becomes clogged with scum, causing wire breakage during processing.Furthermore, the unevenness of the wire diameter may cause processing. This may lead to a decrease in accuracy.

As a method to avoid the above problem, for example,
As disclosed in Japanese Patent No. 91308, a method has been proposed in which an electrode wire is heated in the atmosphere to form an oxide film on the surface thereof. This method focuses on the fact that the copper oxide film has semiconductivity, and aims to reduce the electrolytic current without inhibiting the discharge reduction. If the temperature is as high as 400"C and the material has low heat resistance, the annealing effect will reduce the strength of the electrode wire, making it impossible to increase the wire tension during electrical discharge machining, which will only result in a decrease in machining accuracy. However, the oxide film obtained by heating in the atmosphere is brittle and falls off during handling, which poses a practical problem.

Furthermore, when wire drawing is performed after oxidation, there is a problem in that the quality deteriorates significantly due to falling off and cracking.

[Problem to be solved by the invention]

As a result of studies on the above-mentioned problems, the present invention reduces the shedding of the oxide film and reduces the electrolytic current that impedes the electrical discharge machining conditions without making the outer diameter of the electrode wire uneven or reducing the strength. A method for manufacturing electrode wires for electrical discharge machining has been developed.

[Means and effects for solving the problems] The present invention provides a method for forming an oxide film on the surface of a linear body by immersing a linear body having copper or zinc or an alloy containing these on at least the surface in an oxidizing solution. A method of manufacturing an electrode wire for electric discharge machining, which is characterized in that a wire-like body having at least copper or zinc or an alloy containing these on its surface is immersed in an oxidizing solution to oxidize the surface of the wire-like body. After forming the film,
This is a method of manufacturing an electrode wire for electric discharge machining, which is characterized by performing wire drawing processing of 10% or more.

That is, the present invention prevents the oxide film from falling off by immersing a linear body having copper or zinc or an alloy containing these on at least the surface in an oxidizing solution to form an oxide film on the surface of the linear body. Moreover, an electrode wire for electric discharge machining can be obtained which can reduce the electrolytic current without reducing the strength and improve the machining speed.

In addition, the present invention involves forming an oxide film on the surface of the linear body as described above, and then drawing the wire by 10% or more to further increase the strength of the wire, smooth the surface of the oxide film, and make the wire diameter uniform. This is intended to reduce clogging of debris in the electrode wire guide and reduce wire breakage.

However, in the present invention, the linear body is a wire in which a core wire such as a copper wire, a copper alloy wire, a steel wire, a stainless steel wire, a tungsten wire, or a molybdenum wire is coated with copper or zinc or a copper-zinc alloy. An oxide film is formed on the surface of the linear body by immersing it in an oxidizing solution. And oxidizing? Hz S O = 82 for 7 nights
A 7 volume solution of 0 □ mixed water is good, and the ratio is H, S in volume %.
A good oxide film can be formed by immersion in an aqueous solution containing 0.5 to 20% O4 and 1 to 40% H2O2 for 10 seconds to 10 minutes.

As described above, the present invention uses a chemical to form an oxide film on the surface of a linear body having copper, zinc, or an alloy thereof. Moreover, it has good adhesion to the linear body, and therefore the shedding of the oxide film can be greatly improved. By drawing this wire at a processing rate of 10% or more, an electrode wire with even greater strength can be obtained.

[Example +] An embodiment of the present invention will be described below.

Example 1 Cu-35% Zn alloy wire with a diameter of 0.21φ was heated to H2S○a
It was run in an aqueous solution of 10 g/l, HzO□60 g/l, immersed for 20 seconds at room temperature, and then washed with water and dried. The surface of the alloy wire treated in this way turned black and the formation of an oxide film was confirmed.

Example 2 The wire rod of Example 1 was drawn to a diameter of 0.17 sφ.

(Processing rate: 28%) Comparative Example 1 Using the same wire rod as in Example 1, it was heated to 400'C in the atmosphere.
An oxide film was formed by heating for a period of time.

Comparative example 2 The wire rod was the same as in Example 1 and was completely untreated.

Thickness: 20 mm for the samples of the above examples and comparative examples
An electrical discharge machining experiment was conducted using a 5KD-118 plate as the workpiece. In addition, cracks on the surface of this wire due to self-winding were investigated. These results are shown in Table 1. Note that the relative machining speeds in the table are values when Comparative Example 2 is set as 100.

Table 1 As is clear from Table 1, in all of the examples of the present invention, the processing speed was improved by more than 30% compared to Comparative Example 2, there was no wire breakage during processing, the tensile strength was high, and the oxide film was No machining cracks occur. On the other hand, in Comparative Example 1 using conventional atmospheric oxidation, there was a decrease in tensile strength, cracking of the oxide film, instability of electric discharge during machining, and frequent wire breakage during machining due to wire clogging in the guide.

〔effect〕

As explained above, according to the present invention, since the strength is high and the surface is smooth, there is no occurrence of wire clogging in the guide,
It is possible to obtain an electrode wire that does not break during electric discharge machining and has a high machining speed, which greatly improves the efficiency of wire-cut electric discharge machining, and has a significant industrial effect.

Claims (4)

[Claims] (1) An electrode wire for electric discharge machining characterized in that a linear body having at least copper or zinc or an alloy containing these on the surface is immersed in an oxidizing solution to form an oxide film on the surface of the linear body. Production method. (2) After immersing a linear body having at least copper or zinc or an alloy containing these on its surface in an oxidizing solution to form an oxide film on the surface of the linear body, a wire drawing process of 10% or more is performed. A method of manufacturing an electrode wire for electric discharge machining, characterized in that: (3) Claim 1 or 2, wherein the linear body is a copper wire, a copper alloy wire, or a steel wire, stainless steel wire, tungsten wire, or molybdenum wire coated with copper, zinc, or a zinc alloy. The method for manufacturing the electrode wire for electric discharge machining described above. (4) The method for manufacturing an electrode wire for electric discharge machining according to claim 1 or 2, wherein the oxidizing solution is a mixed aqueous solution of H_2SO_4-H_2O_2.