JPS61103732A - Wire - Electrode wire for electrical discharge machining - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrode wire used in wire electrical discharge machining.

(Back weight technology) Wire electrical discharge machining involves intermittent electrical discharge between the workpiece and a linear machining electrode (referred to as an electrode wire) through a machining liquid such as water. This is a method of cutting a workpiece into a desired shape by relatively moving the workpiece and the workpiece, and is used, for example, in manufacturing various molds.

The electrode wire for wire electrical discharge machining usually has a diameter of 0.2~
0.3-1 copper wire or brass wire, 0.03~G, +11
@ tungsten wire etc. are used. In recent years, progress has been made in processing electrical technology due to the emergence of semiconductors for high speed and large current that are excellent as 1., and control of electrical conditions has made it possible to obtain high processing speeds. It started to appear in a big way.

From this point of view, materials suitable for electrode wires are being actively developed.

For example, in Japanese Patent Publication No. 59-9298 (hereinafter referred to as precedent 1), 5 to 4
An electrode wire consisting of 0% Zn + 0.1-4% AQ, 1 balance Cu has been proposed. Same ■ 1, special public service 57-5
No. 648 (hereinafter referred to as precedent 2) states that Zn or Cd
In JP-A-5G-[No. 12730C, hereinafter referred to as precedent 3], an electrode wire whose core is coated with a metal layer made of an alloy containing at least 50% of a conductive material has a core made of a conductive material and a low melting point metal. An electrode wire has been proposed in which a non-metallic thin film with a semi-stereoscopic effect is applied on top of the layer.

As an electrode wire material for wire electrical discharge machining, ■ it can achieve high machining speed without wire breakage, ■ it can be processed with high tension to obtain high machining accuracy, especially corner machining, and ■ it is inexpensive. is required. In high-speed wire electrical discharge machining, a phenomenon often occurs in which electrode components are transferred onto the workpiece within the machining groove, and a large amount adheres to the inner surface of the machining groove.

Many processing machines have a function of retracting the position of the line via the processing groove when a significant short circuit occurs. In addition to the above-mentioned adhesion phenomenon being a major hindrance to this operation, electrode wires with large adhesion generally have a lower maximum processing speed, so that less adhesion is also an important required characteristic.

Although the above-mentioned examples 1, 2, and 3 are aimed at improving these characteristics, they have the following drawbacks. The electrode wire made of brass containing AQ proposed in Reference 1 is
Since it has excellent strength at high temperatures, it is possible to process it under high tension, but the processing speed that can be obtained is at most one that of ordinary brass wire.
．． It's only 1x. The electrode wires proposed in Precedent Examples 2 and 3 contain soft metals such as Zn or alloy metals, so the maximum processing speed can be 1.3 times or more than that of ordinary brass wires. However, /r(1
Therefore, the tensile strength decreases, and the tension applied during processing also decreases.

(Disclosure of the Invention) The present invention has been made in order to eliminate the above-mentioned drawbacks.
It is an object of the present invention to provide an electrode wire for wire electrical discharge machining which can obtain a high electrical discharge machining speed and which can be processed with high tension.

In the present invention, the surface of the Cu-Zn alloy core material has a composition of 501ri-1% zinc oxide excluding carbon and organic matter in the coating.
(hereinafter referred to as %) This is an electrode wire for wire electrical discharge machining, characterized by having a coating consisting of the above.

In the present invention, a coating whose composition, excluding carbon and organic matter, is 50% or more of zinc oxide means the average value of the profile in the depth direction measured by photoelectron spectroscopy. Remove carbon and organic matter (the reason is
It is effective if the Cu-Zn alloy has a coating whose composition excluding these in the wave film is 50% or more of zinc oxide (2), and the influence of carbon and organic substances is relatively small, and photoelectron spectroscopy (1) This is because the analytical values of organic substances, which are carbon and carbon compounds, are unstable due to the influence of sample contamination, measurement atmosphere, etc. The reason for specifying photoelectron spectroscopy as a measurement method is that in the present invention (in order to perform baking of the resin component after film formation, heat oxidation of the alloy core material, or subsequent wire drawing, the film structure, The composition is often quite complex, making it difficult to analyze by simple chemical analysis, etc.; different analytical methods give different measured values; and the measured values from photoelectron spectroscopy may differ from carbon and organic substances in the film. This is because a Cu-Zn alloy wire having a coating consisting of 50% or more of zinc oxide provides a machining speed 1.3 times or more than a normal brass wire under many electrical discharge machining conditions. If the composition of the film excluding carbon and organic matter is less than 50% zinc oxide, such high processing speed cannot be obtained, especially when the ratio of copper oxide in the film exceeds the ratio of zinc oxide. The electrical discharge machining characteristics are greatly reduced.The profile in the depth direction also shows that carbon, acid poisons, etc. are particularly likely to appear in the outermost layer, and the coating and Cu-
Near the interface of the Zn-based alloy core material, the unevenness of the interface gives a measured value of a mixture of both. It is sufficient that the layer whose composition excluding carbon and organic matter in the coating is less than 50% zinc oxide is present in a portion from several angstroms to several hundred angstroms from the outermost surface, and the coating thickness described below is as follows:
It refers to the thickness of the layer over which such a coating or substance is present. A film whose composition excluding carbon and organic matter in the film is 50% or more of zinc oxide is hereinafter simply referred to as zinc oxide 5.
It is called a film containing 0% or more.

In the present invention, the presence of the above coating significantly stabilizes the machining voltage and machining current during electrical discharge machining. Further, the attachment of the electrode component to the corrugated workpiece is carried out using the electrode wire according to the above-mentioned Example 1. Even under conditions where ■ is almost completely covered with deposits,
Very little. The maximum electrical discharge machining speed can be increased by 20 to 30% compared to ordinary brass wire.

Electrical discharge machining is a machining process that involves repeated small transient electrical discharges in gaps of several micrometers to several tens of micrometers, and although it is difficult to elucidate the detailed mechanism, it is possible to form a coating containing more than 50% zinc oxide. Due to its presence, the work function of the surface is reduced, allowing discharge of high current densities at relatively low temperatures! II
! The above effect is caused by preventing the occurrence of continuous discharge due to the deionization effect of lead, and preventing excessive current generation during a slight short circuit with the workpiece due to an increase in contact resistance. is determined.

If zinc oxide is less than 50%, it is formed on the surface of the material to improve the electrical discharge machining speed, for example, by the following method.

One method is to impregnate a coating material powder into a resin and apply it as a coating film to the surface of the core material. It is also possible to add powder such as Zn or AQ to this t-film and impregnate it to lower the electrical resistance of the surface and reduce the heat generation of the power feeding part during wire electric discharge machining. It is also possible to provide the same effect by baking the resin component after forming the coating film. This coating f
According to the -1 coating method, it is extremely easy to form a film, it is easy to obtain a thin and uniform film, and it is inexpensive.

Other methods include Cu-Zn alloy or AQ, Si,
The present invention is a method for forming a blue atmosphere in a Cu-Zn alloy core material to which Zr + Ti, etc. are added, in which the formation of copper oxide is suppressed and zinc is oxidized. The method is not limited.

In any case, as mentioned above, in order to obtain high processing accuracy, it is necessary that the application with high tension is +iJ, and heating at high temperatures or for a long time at the final size is Undesirable. From this point of view, in any method, after forming a film containing 50% or more of zinc oxide, it is preferable to perform wire drawing -r.

The thickness of such a film is usually 0.01 to 10 μm.
1 is preferred. If the groove is 0.01 μm thick, it is impossible to increase the speed of electrical discharge machining, and if the groove exceeds 10 μm, the high temperature strength decreases and high-precision electrical discharge machining becomes impossible.

Another major feature of the present invention is that the VL film, which has low strength, is thin and has almost the same tensile strength as the core material, and also has the discharge characteristic effect as described above. It is possible to perform electrical discharge machining under high tension. The presence of a coating containing 50% or more zinc oxide generally allows processing at 5-20% higher tensions.

Furthermore, in the present invention, in addition to the Cu-Zn alloy containing 20 to 40% Zn, for example, AQ+Sr+Zr is used as the core material.
By using a Cu-Zn alloy containing additive elements such as , Ti, etc. that improve the tensile strength, especially I@i temperature strength, the tensile strength of ordinary brass wire is 70 to 80% (70 to 85%).
Even electrical discharge machining is possible under tension of kg/@■'').

(Example 1) 1 part of ethyl cellulose was added to 1 part of zinc oxide with particle size o, o: +~0.3 μm, and methyl ethyl ketone (MEK) was added.
A lacquer paint containing zinc oxide was prepared by diluting it with water.

This intermediate material was applied to the yellow inner line of 0.2 GO ± 0.002 sn φ by adding various additive elements shown in Table 1 to the Cu05%-Zo35% total and drying. I created a line by .

These lines and 0 with the addition of various additive elements shown in Table 1
, 200±0. [Wire electrical discharge machining was performed under the following conditions using a 102 snφ brass wire (conventional example) as an electrode wire.

Electrical discharge machining conditions Machining fluid specific resistance (water) 1.0XlG'Ω/as Pulse width 4μsec.

Pause time: 3.5 μsec.

Electrical voltage 110V Capacitor capacity 1.2μF Processing voltage 4O-80V Processing feed rate Maximum without disconnection (+11 to 1 submersion Processing fluid pressure Upper nozzle 5kg/c♂ Lower nozzle
5/C■2 Workpiece Maximum electrical discharge during electrical discharge machining of SKD-II material with thickness GOsm [The speeds are as shown in Table 1.

Table 1 From Table 1, it can be seen that the electrical discharge machining speed of the present invention is improved by 18 to 36% compared to the conventional example.

(Example 2) O,S%5i-0,1%7'1-35% of 0.5*φ
A Cu-Zn alloy wire consisting of Zn and the remainder Cu was prepared. When this was heated at TOO°C for 1 hour in an atmosphere of 104 atm and 02 partial pressure 2XIG-' atm, a gray-black film was formed. Even when this wire was drawn to a diameter of 0.3 mm, this coating remained. The surface coating was analyzed by photoelectron spectroscopy, excluding inorganic and organic carbon, and the profile of the composition in the depth direction was measured, as shown in the drawing. When this wire was used as an electrode wire for wire electrical discharge machining under the same electrical discharge machining conditions as in Example 1, the electrical discharge machining speed was 1.1 m/min.

(Effects of the Invention) The electrode wire for wire electrical discharge machining of the present invention configured as described above has the following effects.

(b) In order to form a coating on the surface of the Cu-Zn alloy core material, the composition of which is 50% or more of zinc oxide, excluding carbon and mechanical components,
As mentioned above, the inter-electrode voltage and machining current during electrical discharge machining are extremely stable, and because there is little adhesion of electrode components to the workpiece, a high electrical discharge machining speed can be achieved.

This not only shortens machining time, but also means that the probability of wire breakage at the same speed is low, making it possible to achieve high-speed machining during manual machining and high reliability during unmanned detours. .

(0) The above film with low strength is thin and has almost the same τ as the core material.
It not only has a tensile strength of

The biggest effect of this is to improve machining accuracy, but by suppressing the vibration of the electrode wire and reducing the width of the machining groove, the total removal amount when machining the same thickness, same length, and It is thought that by reducing the , it is possible to further improve the machining speed.

(c) The coating on the surface of the core material can be formed by methods such as coating with paint and heating oxidation as described above, so production is easy and inexpensive.

[Brief explanation of drawings]

The figure is a composition diagram showing the composition of a film in an example of the present invention. shieisa (za)

Claims (1)

[Claims] (1) An electrode wire for wire electrical discharge machining, which has a coating on the surface of a Cu-Zn alloy core material, the composition of which is 50% by weight or more of zinc oxide, excluding carbon and organic substances.