JPS61252025A - Electrode wire for wire electric discharge machining and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the efficiency of electric discharge machining by providing a copper-zinc alloy layer having higher zinc concentration in the surface layer on the outer peripheral surface of a copper coated steel wire and zinc sulfide, copper sulfide and carbon grains dispersed, and further black coating said alloy layer. CONSTITUTION:A copper-zinc alloy layer 12 is provided in which zinc sulfide, copper sulfide and carbon grains with 0.1-15mum of thickness are dispersed on the outer peripheral surface of a copper coated steel wire 11 of core material and concentration gradient of zinc becomes higher toward the surface layer from copper foundation. Further, a black coating 13 consisting of zinc sulfide, copper sulfide and carbon grains and having 0.1-5mum of thickness is provided on the outermost layer to form total about 0.2mm of diameter. Further copper is coated on the steel wire 11 such that the rate of sectional area of a the copper to the total sectional area, i.e. coating rate is 10-70%. Thus, high temperature strength is obtained, disconnection is prevented and the operational efficiency of electric discharge machining can be improved.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an electrode wire for wire electrical discharge machining used in wire electrical discharge machining to machine a workpiece (workpiece) by the melting action of electric discharge, and its manufacture. It is related to the method.

"Prior Art" FIG. 2 schematically explains a general wire electrical discharge machining method. This processing method involves inserting the electrode wire 3 into a start hole 2 previously drilled in the workpiece 1, and running the electrode wire 3 in the insertion direction (in the direction of the arrow in Fig. 2). By generating an electric discharge between the inner wall surface of the hole 2 and moving the workpiece 1 in a direction perpendicular to the insertion direction, the workpiece 1 is melted and processed into a predetermined shape along the movement trajectory. It's a method. In this figure, electrode wire 3
is continuously fed out from the supply reel 4, passes through the rollers 5 on both sides of the workpiece 1, and is wound onto the take-up reel 6, and the tension placed between the take-up reel 6 and the rollers 5 The tension is adjusted by rollers 7. Although not shown, machining fluid is supplied to the electrical discharge machining portion to cool the electrode wire 3 and remove machining debris.

Conventionally, the electrode wire 3 used in such wire electric discharge machining
For example, copper wire with a diameter of about 0.05 to 0.3 IIli,
Brass wire (65% Cu, 35% Zn alloy), galvanized brass wire, or for special purposes, tungsten wire, molybdenum wire, etc. are used.

[Problems to be Solved by the Invention] By the way, these electrode wires 3 are exposed to about 300
℃, which places a large thermal burden on the electrode material itself, while also applying tension when adjusting the tension of the tension roller 7, which is performed to maintain stable discharge and increase machining accuracy and machining speed. High strength (tensile strength at high temperatures) is required. However, although copper wire has good wire drawability into fine wire as electrode wire,
The tensile strength is low, and there is a risk that new wire will form during use, significantly reducing the efficiency of electrical discharge machining work. In addition, brass wire
The tensile strength at room temperature is about twice that of copper wire, but 3
The high temperature strength of around 00°C is only slightly higher than that of copper, and if you try to increase the processing speed, there is a tendency for the wire to break.

In general, in the case of galvanized brass wire, although the electrical discharge safety due to zinc is increased, the high-temperature strength decreases due to the presence of the galvanized film, and if you try to increase the processing speed, there is still a tendency for the wire to break. There is. Furthermore, although tungsten wire and molybdenum wire have high high-temperature strength, they have problems such as poor wire drawability and high cost as electrode wires used as consumables.

"Means for Solving the Problems" The wire electrical discharge machining electrode wire of the present invention was made to solve the above-mentioned problems in conventional wire electrode wires, and has a copper coverage of 10 to 70%. The outer peripheral surface of the coated copper-coated steel wire is coated with a concentration gradient such that the zinc concentration increases from the copper base to the surface layer over a thickness of 0.1 to 15 μm, and zinc sulfide, copper sulfide and carbon particles are added. A dispersed copper-zinc alloy layer is provided, and this is further coated with a black coating consisting of zinc sulfide, copper sulfide, and carbon particles.

In addition, the method for manufacturing a wire electrical discharge machining electrode wire of the present invention includes forming a zinc layer on the outer circumferential surface of a copper-coated steel wire by electrolytic galvanizing in a galvanizing bath containing an additive containing a sulfur-containing compound. After that, wire drawing processing and further heat treatment are performed to form a copper-zinc alloy layer, in which zinc sulfide, sulfide steel, and carbon particles are dispersed, and the zinc concentration is increased from the copper base to the surface layer. In this method, a concentration gradient is applied to increase the concentration, completely converting the lead discharge layer into a copper-zinc alloy layer, and forming a black film consisting of zinc sulfide, copper sulfide, and carbon particles in the outermost layer.

In the electrode wire for wire electrical discharge machining (hereinafter referred to as wire electrode wire), if the copper coverage of the copper-coated brass wire is less than 10%, the electrical conductivity will be low, resulting in a decrease in discharge performance and a decrease in machining speed. If it does not increase and is greater than 70%, the high temperature strength will be low, making it easy to break when the tension is increased. In addition, if the copper-zinc alloy layer does not exist, the copper base is exposed, so the discharge performance, that is, the machining speed, decreases significantly.

Further, unless the copper-zinc alloy layer has a concentration gradient such that the zinc concentration increases from the copper base toward the surface layer, a sufficient increase in processing speed cannot be obtained.

Furthermore, the thickness of the copper-zinc alloy layer, which has a concentration gradient and in which zinc sulfide, copper sulfide and carbon particles are dispersed, is
If it is less than 0.1μI, sufficient discharge performance cannot be obtained,
Either the effect of increasing the machining speed cannot be obtained, or the iron content of the workpiece (mainly in the case of steel materials) and the copper content of the electrode wire cause a melting reaction and have a strong tendency to adhere to the machined surface. Accuracy deteriorates. If the thickness of the copper-zinc alloy layer having a concentration gradient is thicker than 15 μm, the strength will be lowered and the wire will be more likely to break, and the heat treatment time will be longer and the equipment cost will be higher, which is economically disadvantageous.

Furthermore, if there is no black film made of zinc sulfide, copper sulfide, and carbon particles with a thickness of 0.1 to 5 μm formed on the outermost layer, initial discharge (discharge occurs between the wire electrode wire and the workpiece) (time), the discharge is not gentle and evenly distributed, but locally concentrated discharge may occur, making the wire more likely to break. The thickness of this black film is 0.1 μ-
If the number is less than 5 μm, the above effect cannot be obtained, and if the number exceeds 5 μm, the strength will be significantly lowered, causing problems.

``Example'' Hereinafter, a preferred embodiment of the present invention will be described. As shown in FIG. A copper-zinc alloy layer 12 is provided with a constant thickness of 15 μl, in which zinc sulfide, copper sulfide and carbon particles are dispersed, and the concentration gradient is such that the zinc concentration increases from the copper base toward the surface layer, Furthermore, the outermost layer consists of zinc sulfide, copper sulfide and carbon particles with a thickness of 0.
A black skin wA13 of 1 to 5 μm is provided, and the overall diameter is approximately 0.2111 mm. The copper-coated steel wire 11 is a so-called steel wire, iron wire, alloy steel wire, or other steel wire coated with copper at a coverage rate of 10 to 70%. However, the coverage here means the ratio of the cross-sectional area of the body portion to the cross-sectional area of the entire body.

Such a wire electrode line is manufactured, for example, by the following method. For example, a copper-coated steel wire with a diameter of 0.491 rA was placed in a zinc chloride bath (IJ) containing 42 g of zinc chloride and 210 g of ammonium chloride (J) with additives containing sulfur-containing organic compounds. ) and electrogalvanized.

Examples of additives containing the above-mentioned sulfur-containing organic compounds include molecules such as anionic surfactants such as sodium alkyl sulfates, sodium alkylbenzenesulfonates, sodium olefin sulfates, and cationic surfactants such as alkylpyridinium sulfates. Surfactants containing sulfur are mainly used because they do not have a negative effect on the plating bath, but aromatic carboxylates, water-soluble cationic polymers, aromatic aldehydes, higher alcohols, etc. can also be used. As a result, on the outer peripheral surface of the copper-coated steel wire,
A zinc layer of a predetermined thickness containing and dispersing the above additives is formed. At this time, a predetermined amount of the above additive is also deposited on the surface layer of this zinc layer.

Next, the copper-coated steel wire with the galvanized layer formed thereon is drawn to have an overall diameter of 0.211, and then heat-treated by heating in the atmosphere using an oven or the like. Through this heat treatment, the zinc layer changes to a copper-zinc alloy layer with a concentration gradient such that the zinc concentration increases from the copper base to the surface layer, and the sulfur in the additive reacts with the zinc and copper, causing organic matter to form. is carbonized, zinc sulfide, copper sulfide and carbon particles are dispersed in the alloy, and at the same time a black film consisting of zinc sulfide, sulfide steel and carbon particles precipitated from the alloy layer is formed on the alloy layer.

The wire electrode wire formed in this way has excellent high-temperature strength and conductivity because it uses the copper-coated steel wire 11 as the core material, and has a zinc concentration that increases from the copper base toward the surface layer. Excellent discharge performance is exhibited due to the presence of the copper-zinc alloy layer 12 which has a WJ gradient and has zinc sulfide, copper sulfide and carbon particles dispersed therein. Furthermore, the copper-zinc alloy IIJ12 prevents copper from adhering to the workpiece during discharge. Furthermore, since the outermost layer has a black coating 13 made of zinc sulfide, copper sulfide, and carbon particles, the initial discharge does not become a concentrated discharge at J5, but instead becomes a gentle and evenly dispersed discharge, and subsequent discharges occur all around the circumference. The discharge is relatively uniform across the line, making it difficult to break the wire.

Next, experimental examples will be shown to clarify the effects of these wire electrode lines.

In this experimental example, the copper coating rate of the copper-coated steel wire 11 is such that the concentration gradient increases from the copper base to the surface layer, and the copper coated steel wire 11 has a concentration gradient such that the zinc concentration increases from the copper base to the surface layer, and the copper coated steel wire 11 has copper sulfide curved lead, copper sulfide, and carbon particles dispersed therein. The thickness of the zinc alloy layer 12 and the black skin made of zinc sulfide, copper sulfide and carbon particles g! Life electrodes with a diameter of 0.2 mm with various thicknesses of 13 and ordinary copper wires and brass wires (Cu65%,
Machining speed, machining accuracy, wire breakage frequency (high temperature strength, discharge stability), and economical efficiency of Zn35%), galvanized brass wire, and copper-coated steel wire with copper-zinc alloy layer without concentration gradient. A comparative test was conducted to evaluate the

The results of this comparative test are shown in Table 1. However, for electric discharge machining, a workpiece with a thickness of 201IIl (SKD-11
) was processed by cutting out a 3011II11 square board. The processing conditions at this time are as follows.

Applied voltage: 110V Pulse time 20N→5μ5 OFF→5μs Peak current: 10A Capacitor transmission: 0.8μF Processing fluid: KA water Electrode wire tension Near 50Qf In addition, the processing speed is the copper wire processing speed (0.8mmZ minute )
It is expressed as a ratio when this is taken as a standard.

The machining accuracy is as follows: A (less than 0.01mm), B (0.01~0°03n+m), C (0.01mm), C (0.01mm), B (0.01~0°03n+m),
Larger than 03mm) and it was on the front.

The frequency of wire breaks is A (stable without wire breakage) in descending order of the number of wire breaks.
, B(1) (If the machining speed is increased, there will be a disconnection.), B(2
) (If the tension is greater than 750of, there will be a disconnection), B
(3) (Early stage of discharge - disconnection may occur when the wire electrode starts discharging between it and the workpiece.) C (Frequent disconnection)
It was expressed as Furthermore, for economical efficiency, cases where the production cost of the brass wire can be made cheaper are shown as ○, and cases where it becomes more expensive are shown as x.

As is clear from Table 1, the wire electrode wire has a copper coverage of 10 to 70%, a thickness of the copper-zinc alloy layer of 0.1 to 15 μm, and a thickness of the black film of 0.1 to 15 μm. 1~
Those satisfying the present invention condition of 5 μl include copper wire, brass wire, galvanized brass wire, and zinc-
It can be seen that this electrode wire is superior in processing speed, processing accuracy, disconnection resistance, and economical efficiency compared to other electrode wires containing copper-coated steel wires coated with a copper alloy layer.

A copper coated steel wire with a diameter of 0.196u and a coverage rate of 60% is used as a core material, and a zinc sulfate bath (1) containing the above additives contains sulfuric acid.
14 mol of FfA acid bent lead (aqueous solution containing 0.23 mol of FfA acid bent lead) and electrolytic galvanized to form a zinc layer with a thickness of 2 μm in which the additive is dispersed and the additive is attached to the surface layer.
Thereafter, a wire electrode wire obtained by heat treatment in the atmosphere for 1 hour using an oven and a wire electrode wire obtained by heat treatment by passing through a tube furnace set at 500 ° C. instead of an oven. Also, excellent results were obtained similar to the test results of the wire electrode line satisfying the conditions of the present invention in the above experimental example. In addition, the above 0
．． Similar results were obtained when wire drawing was performed after heat treatment in the process of obtaining 0.2 shoes from 49 m.

Note that since the heat treatment is performed in the atmosphere, naturally some of the zinc and copper are oxidized, producing zinc oxide and copper oxide, which are thought to coexist in the black film.

As is clear from this, in the manufacturing method of the present invention, heat treatment is performed on a copper-coated steel wire having additives dispersed therein and a zinc layer, which is also adhered to Table R1, on the outer peripheral surface. The zinc layer is transformed into a copper-zinc alloy layer in which zinc sulfide, copper sulfide, and carbon particles are dispersed, and the concentration gradient is such that the zinc concentration increases from the copper lump toward the surface layer. .

It can be seen that the step of producing a black film consisting of copper sulfide and carbon particles is an important step to obtain a wire electrode wire of excellent quality.

"Effects of the Invention" As explained above, according to the present invention, the following excellent effects can be obtained.

(2) Since the core material is a copper-coated steel wire coated with copper at a coverage rate of 10 to 70%, high temperature strength can be increased while maintaining high electrical conductivity. In other words, even when a high current flows, the temperature of the wire electrode wire does not rise due to Joule heat, so in order to further increase the processing speed, even when a high current flows and the wire electrode wire heats up, the high temperature strength is reduced. Since it is high, wire breakage can be prevented and the efficiency of electrical discharge machining work can be increased.

■ 0.1 to 15 on the outer peripheral surface of copper-coated steel wire with good electrical conductivity.
A copper-zinc alloy layer was created in which zinc sulfide, copper sulfide, and carbon particles were dispersed over a thickness of 1 μl, and a concentration gradient was created so that the zinc concentration increased from the copper mass toward the surface layer. Furthermore, the discharge performance is improved, copper is prevented from adhering to the workpiece due to surface exposure of the copper layer, and machining accuracy is increased, and a decrease in machining speed can be prevented.

■ Since the outermost layer is coated with a black film made of zinc sulfide, copper sulfide and carbon particles over a thickness of 0.1 to 5 μm, the initial discharge does not become concentrated, but instead becomes a gentle, evenly dispersed discharge. Wire breakage can be prevented.

■ The material has good wire drawability and can be manufactured at low cost. In other words, in the wire electrode wire of the present invention, the characteristics of the steel, copper, copper-zinc alloy layer, and black coating are extremely well utilized and adjusted, and the synergistic effect of these allows the above-mentioned effects of ■■O■ to be obtained. .

■ Additives containing sulfur-containing organic compounds are dispersed inside the outer circumferential surface of copper-coated steel wire, and a zinc layer is attached to the surface layer by electroplating, followed by heat treatment. A copper-zinc alloy layer in which copper and carbon particles are dispersed and the zinc concentration increases from the copper lump to the surface layer, and the outer layer of this is a black film consisting of copper sulfide, copper sulfide, and carbon particles. Thus, a wire electrode line with stable discharge performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the electrode wire for wire electric discharge machining of the present invention, and FIG. 2 is a schematic perspective view illustrating the outline of a general wire electric discharge machining method. 11...Copper coated steel wire, 12...Copper-zinc alloy layer, 13...L has a coating. Figure 1 Figure 2

Claims (3)

[Claims] (1) A copper-coated steel wire made by coating a steel wire with copper at a coverage rate of 10 to 70% is used as the core material, and this copper-coated steel wire has a thickness of 0.
A copper-zinc alloy layer in which zinc sulfide, copper sulfide and carbon particles of 1 to 15 μm are dispersed and has a concentration gradient such that the zinc concentration increases from the copper base to the surface layer is provided,
A wire electrode wire for electrical discharge machining, further comprising a black coating of 0.1 to 5 μm consisting of zinc sulfide, copper sulfide and carbon particles. (2) On the outer peripheral surface of a copper-coated steel wire made by coating a steel wire with copper,
Electrogalvanizing is performed in a galvanizing bath containing an additive containing a sulfur-containing organic compound to form a zinc layer with the additive interposed inside and attached to the surface layer, and then heat treatment is performed. A copper-zinc alloy layer is formed in which zinc sulfide, copper sulfide and carbon particles are dispersed, and the concentration gradient increases from the copper base to the surface layer, and zinc sulfide and copper sulfide are formed in the outermost layer. and a method for producing a wire electrode wire for electrical discharge machining, the method comprising producing a black film consisting of carbon particles. (3) The method for manufacturing a wire electrode wire for electric discharge machining according to claim 2, characterized in that wire drawing is performed as a pre-process or post-process of the heat treatment.