JPS60262930A - Electrode wire made of copper alloy for wire discharge processing - Google Patents

Abstract

PURPOSE:To obtain the titled electrode wire easy in manufacture and superior in workability for passing through die and discharge processing characteristic by increasing the concn., of a low m.p. metallic element contained in a copper alloy wire for wire discharge processing, so that the nearer to the outer surface, the higher said concn. at least at the surface layer. CONSTITUTION:The copper alloy wire to be a material of said electrode wire is passed through molten bath of low m.p. metallic element (metal), preferably, Bi, Sb, Zn, In, Sn, Pb, Mg or Al after drawing, next, said metal is wiped off by asbestos, etc. to the extent in which said metal is adhered partially thereon. Further, said wire is annealed after drawing to diffuse adhered said metal into the copper alloy wire to obtain the state in which the nearer to the outer surface, the higher the concn. of said metal and the lower the copper concn. accompanyingly therewith, the nearer to the center layer, the tendency of both is reversed. Further, preferably, whole copper concn. is about 61-95%, and 0.1-5% at the extreme surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electrode wire for wire electrical discharge machining.

Background technology Wire electrical discharge machining (hereinafter simply referred to as electrical discharge machining) is
Electric discharge is caused between the workpiece and an electrode wire for wire electrical discharge machining (hereinafter referred to as electrode wire) using a machining fluid such as water as a medium,
This is a conventional method in which the electrode wire and the workpiece are moved relatively to cut the workpiece into a desired shape.

In this electric discharge machining method, the electrode wire usually has a diameter of 0.
．． A long wire of 0.03 to 0.25 is prepared and used by sequentially supplying new wire to the electrical discharge machining part.

Conventionally, electrode wires have been made of hard copper wire, brass wire, tungsten wire, Zn or AJ! Covered brass wire, 0.1 to 4 U-2
Although 0 to 381 Zn-Cu alloy wire is used, hard copper wire and brass wire are subject to limitations in machining speed and dimensional accuracy due to electrode components adhering to the surface to be machined during discharge.

Although tungsten wire has a low electrical discharge machining speed and good surface finish and dimensional accuracy, it is difficult to manufacture and expensive. Brass wire coated with Zn or glue is coated with a low-melting point metal, so when the electrode wire is cut into a needle-like shape using flame etc. in order to pass it through a die during electrical discharge machining, the tip becomes ball-shaped. It is difficult to pass through a die, resulting in poor workability.Furthermore, the tensile strength of the coating layer is inferior to that of the core material, resulting in poor processing accuracyo O, 1~41 A,,e20~38
%Zn Cu alloy wire has poor wire drawability compared to ordinary brass wire, and depending on the electrical discharge machining conditions, a large amount of copper dislocation and adhesion may occur.

Structure of the Invention The present invention has been made to eliminate the above-mentioned drawbacks, and it is extremely easy to manufacture and draw electrode wires, has high mechanical strength, can take high tension during electrical discharge machining, and has high processing accuracy. It has a large surface area and has a rough surface, so it has good wettability with water, and the associated cooling effect allows for high processing speed.
Because the surface has a high concentration of low-melting metal elements, there is less adhesion of electrode components to the workpiece surface, resulting in a good finish.Furthermore, the low-melting point part is extremely thin, so when cutting the electrode wire, pole formation does not occur at the tip. Therefore, it is an object of the present invention to provide an electrode wire that is easy to work with through a die and is inexpensive. In addition,
The reason why the surface of the electrode wire described above is rough is that the surface layer is made of an alloy with a high concentration of Zn, for example, and the surface layer has low ductility during wire drawing.
This is because surface roughness occurs. That is, for the electrode wire of the present invention, for example, a copper alloy wire as a raw material is drawn, and then passed through a molten metal of a low melting point metal or an alloy of the metal, so that the low melting point metal or alloy is coated on the copper alloy wire. After wiping with asbestos or the like to the extent that it partially adheres, the wire is further drawn and annealed to diffuse and eliminate the adhered low melting point metal or alloy into the copper alloy wire. It can also be easily manufactured by heating in an inert gas atmosphere after forming a low melting point metal layer.

The low melting point metal element used when carrying out the present invention is B1
, Sb, Zn, Cd, Pu, In, Sn,
Like Pb, Mg or 4S, the melting point is 15
Preferably, the angle is from 0 to 700°. Although alkali metals such as K, Na, and phosphorus have low melting points, they cannot be used because they react violently with water, which is the medium for electrical discharge machining. Additionally, mercury, which is liquid at room temperature, is highly toxic and inappropriate.

Among the above elements whose melting point is 150 to 700° C., Cd is somewhat problematic in terms of toxicity, and Pu is not suitable because it is expensive and has radioactivity. Therefore, the elements that are practically used are Bi, Sb, Zn, In, Sn, and P.
b%Mg or limited to M.

As shown in Figures 1 and 2, the electrode wire thus obtained has a high concentration of low melting point metal elements on the outer surface, and a correspondingly low concentration of copper elements, and this tendency reverses as it approaches the center layer. .

Here, it is preferable that the copper element concentration on the outermost surface is 0.1 to 5 mm, and the overall copper element concentration is 61 to 95 mm. The reason why the copper element concentration in the surface layer was limited to 0.1 to 5 is that the concentration of low melting point metal elements is high below 0.1 coefficient, so when cutting the electrode wire when passing it through the die, a ball may form at the tip. If the width exceeds 5, the amount of copper deposited on the surface to be machined increases during electrical discharge machining, resulting in poor finished surface condition. Next, the reason why the overall copper element concentration was limited to 61-95% is that below 61%, the conductivity is low and the electrical discharge machinability is poor.
If the coefficient is 5 or more, the tensile strength is small, and the tension during electrical discharge machining must be lowered, resulting in poor machining accuracy.

The features of the present invention will be summarized below.

As described in the conventional example, the presence of a low melting point alloy element on the surface is certainly highly effective in suppressing electrical discharge machinability, particularly the phenomenon in which electrode components adhere to the workpiece during electrical discharge. However, when the surface is formed of a single low-melting point metal layer, the low-melting point metal is considerably consumed by discharge, and a thickness of preferably 10 μm or more is required to exhibit the effect. This results in a decrease in processing accuracy due to the aforementioned decrease in tensile strength, and a deterioration in workability due to ball formation during flame cutting. The present invention maintains the adhesion prevention effect by increasing the concentration of a low melting point metal element on the outer surface, which has a large influence on the adhesion phenomenon, and suppresses consumption due to discharge by increasing the Cu concentration inside the conductor. Moreover, since the layer with a high concentration of low melting point metal having low tensile strength is limited to the extreme surface, there is almost no decrease in tensile strength and, of course, there is no problem of ball formation. If the Cu element on the outermost surface is 0.1 to 5, it will not have any adverse effect on adhesion. Due to its high tensile strength, high tension can be applied during processing, which further results in reduced adhesion.

Hereinafter, the electrode wire of the present invention will be explained based on Examples.

Examples Example 1゜Invention II! 79% Cu of 1.0+n+nO shown in 12
- After passing a 30% Zn brass wire through molten Zn (temperature 450°C) for 5 seconds, it was squeezed out with asbestos, and then
．． The wire was drawn to 5rImO.

Next, after annealing at 500°C for 124 hours, the wire was further drawn to obtain a 0.2 mm* electrode wire. Using this electrode wire,
When cutting 5KD-15 tool steel with a thickness of 25III11, the processing speed ratio was 1 when the conventional hard copper wire was set as 100.
A good result was obtained in which the ratio of the amount of copper deposited on the processed surface of 801 was 20. Furthermore, when cutting the electrode wire when passing it through the die, no ball was formed at the tip, and the electrode wire could be passed through the die smoothly.

Example 2゜65% C of 0.8 iunO shown in the present invention ll & 15
U-35%Zn Brass wire with 8μ S by electroplating
Electroplating of n was applied. Thereafter, the wire was drawn to 0.5 who. Next, after diffusion annealing at 270°C for 2 hours, the wire was further drawn to obtain an electrode wire of 0.2+nnl'. When this electrode wire was used to cut 9KD-15 tool steel with a thickness of 25 mm, the processing speed ratio was 160 when the conventional hard copper wire was set as 100, and the ratio of the amount of copper deposited on the workpiece surface was 45. and hair)
I got the results. Also, when cutting the electrode wire when passing through the die,
No ball was formed at the tip and it could be passed through the die smoothly. In addition, in both Examples 1 and 2, the brass wire of 1, OJ5', 0.80, which is the material of the electrode wire, could be obtained from a base material of 5 mm0 without intermediate annealing.

Comparative Example 1゜ 1. shown in Comparative Example No. 0.2. Orrmo's 65% Cu
-33% Zn-24 AJ wire was drawn and the heat treatment process was repeated several times to obtain a 25iI electrode wire.
When cutting II+ thick 5KD-15 tool steel, the machining speed ratio was 1601 when the conventional hard copper wire was 100, and the ratio of copper adhesion to the workpiece surface was 70, indicating that the latter characteristics were not very good. Three intermediate annealing treatments were required to draw a wire from a 5IIIIIIO base material to 1.0 g.

Comparative Example 2゜ Comparative Example 1 1 shown in N&L1. 70%Cu of OvmX
-301Zn brass wire is heated in molten Zn (430°C) for 5 minutes.
After passing the wire for a second, the wire was drawn directly without removing the Zn attached to the surface to obtain an electrode wire of 0.2IIIIIO. When cutting 5KD-15 tool steel with a thickness of 25 mm using this electrode wire, the processing speed ratio was 160 when the conventional hard copper wire was 100, and the ratio of the amount of copper deposited on the workpiece surface was 20. As a result, when cutting when passing through the die, there are 0 and 3 at the tip.
Balls of MO formed, making the die threading process extremely difficult. These results are shown in Table 1.

As shown in Table 1, the electrode wires of the present invention #I&lL1~
No. 6 has a copper element concentration on the outermost surface in the range of 0.5 to 15%, and has good die passing workability and electrical discharge machining characteristics (machining speed, amount of copper deposited on the surface to be machined).

Comparative Example Nnl has excellent electrical discharge machining properties, but has poor die threading workability, and Comparative Example No. 2 has poor wire drawability.
The disadvantages are that many intermediate annealing steps are required before the electrode wire is manufactured, and that a large amount of copper adheres to the surface to be machined during electrical discharge machining.

Effects As mentioned above, the electrode wire according to the present invention is easy to manufacture and
It has good die threading workability and good electrical discharge machining characteristics.
Therefore, it exhibits a remarkable effect of reducing the running cost of electrical discharge machining.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing examples of concentration distributions of low melting point metal elements and copper elements in the diametrical direction in the longitudinal section of the wire electric discharge machining electrode wire of the present invention. The horizontal direction indicates the position, and the vertical direction indicates the concentration of the low melting point metal or copper. 1st grade officer 2nd grade

Claims (1)

Claims: (1) A copper alloy electrode wire for wire electrical discharge machining, characterized in that the concentration of a low melting point metal element contained in the metal wire is higher at least in the surface layer as the outer surface of the metal wire increases. (2) Low melting point metal element is Bi, Sb, Zn, I
n%Sn. The steel alloy electrode wire for wire electrical discharge machining according to claim (1), characterized in that the electrode wire is Pb, Mg or quartz. (Claim (1) or (2) characterized in that the 31Cu element concentration as a whole is in the range of 61 to 95)
Steel alloy electrode wire for wire electrical discharge machining. (4) Wire electrical discharge machining according to claim (1), (2) or (3), characterized in that the Cu element concentration on the outermost surface is 0.1 to 5. Copper alloy electrode wire.