JP2003039246A - Electrode wire for wire electric discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode wire for wire electric discharge machining, which has sufficient tensile strength even for high temperature generated in electric discharge machining and is difficult to break even in high speed machining. SOLUTION: The electrode wire for the wire electric discharge machining has a functional multilayer composite structure. Material of a core wire is steel, alloy steel, or iron having high temperature tensile strength higher than that of brass to give a property difficult to break. A high zinc Cu-Zn alloy layer (zinc concentration of 45-65%) is formed on the surface of the steel wire so as to have the thickness of 10-20% of the final outside diameter to improve the electric discharge machining property. Further, a Zn layer is formed on the high zinc Cu-Zn alloy layer so as to have the thickness of 0.5-3% of the final outside diameter to improve electric discharge stability and machining speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode wire used in a wire electric discharge machine, and particularly to increase a machining speed for scraping a cutting object in order to keep the machining cost low.
The present invention relates to a wire electric discharge machining electrode wire that can achieve higher speed and discharge stability than conventional wires.

[0002]

2. Description of the Related Art Wire electrical discharge machining is a process in which an electrical discharge phenomenon is caused between an electrode wire for electrical discharge machining and a workpiece, and the workpiece is cut by thermal energy generated by the electrical discharge. Suitable for metal processing with complicated shapes such as press dies. In such wire electric discharge machining, it is required that the finished state of the surface of the workpiece and the dimensional accuracy be good and that the machining time be short. 65/35 brass (65% Cu-35% Zn) has been widely used as this electrode wire from the past, but various methods have been used to study the electric discharge machining speed faster than this structure. ing. One of them is to increase the Zn concentration in the brass composition. (Journal of Copper and Copper Technology 26 (19
87)) In addition, many proposals have been made for a composite structure in which an alloy layer having a higher Zn concentration is formed on the wire surface and a manufacturing method thereof. (Japanese Patent Publication No. 57-5648, Japanese Patent Publication No. 62-218026,
According to these various examinations, the electrical discharge machining speed may differ depending on the comparison method, but when the machining is performed so that the surface roughness of the obtained workpiece is equal, 65
EDM speeds of 1.2 to 1.5 times that of / 35 brass have been obtained. From this, it is a known fact that the high zinc brass and the high zinc zinc-zinc alloy layer improve the processing speed.

[0003]

However, during electric discharge machining of the electrode wire for wire electric discharge machining, 200 to 400
It is said that the high temperature of ℃, and despite the need for tensile strength under high temperature, the copper-zinc component ratio of brass,
When the zinc content is high, the tensile strength at high temperature tends to decrease, and further, when the processing speed is increased, the frequency of wire breakage increases.

[0004]

The electrode wire for wire electric discharge machining according to the present invention is for solving the above-mentioned problems, and a steel wire, an alloy steel wire or an iron wire having a high-temperature tensile strength higher than that of brass is used for the central core material. Has a function that wire breakage does not easily occur even if severe processing conditions are selected.Next, the surface of this steel wire is made of high zinc with a thickness of 10 to 20% of the outer diameter. By having a copper-zinc alloy layer (zinc concentration is 45 to 65%), it has a function of improving electric discharge machining, and further, the surface has a thickness of 0.5 to 3% of the finished outer diameter. It is a multilayer composite structure according to functions, which has a function of forming a zinc layer and improving discharge stability and processing speed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the electrode wire 1 for wire electric discharge machining of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view of an electrode wire 1 for wire electric discharge machining according to the present invention, in which a core material 2 of a steel wire is used in the center, and a zinc concentration of a thickness of 10 to 20% of the finished outer diameter is used on the surface thereof. ~ 65%
Of the high-zinc copper-zinc alloy layer 3 and further provided with a zinc layer 4 having a thickness of 0.5 to 3% of the finished outer diameter on the surface thereof. Since the steel wire 2 is for the purpose of improving the high temperature tensile strength, it is sufficient if the high temperature tensile strength is higher than that of brass, and not only the steel wire but also an iron wire, an alloy steel wire or the like may be used. Next, regarding the high-zinc copper-zinc alloy layer 3, it is known that the wear part of the wire electrode used for electrical discharge machining is about 10% of the outer diameter finished from the surface layer, and this part is high zinc The copper-zinc alloy layer may be formed, but it is not preferable that the core material is exposed during processing, so 12 to 17% is a more preferable thickness. Further, the high-zinc copper-zinc alloy layer 3 is produced by thermal diffusion in the atmosphere after copper plating is applied on the surface of the steel wire 2 and further zinc plating is applied on the surface of the copper layer. Depending on the heat treatment conditions, a copper-only layer may remain on the surface of the core material, but the zinc concentration is 45% from the outer periphery of the brass layer toward the core material at a zinc concentration of 45%. If a copper-zinc alloy layer with a high zinc content of up to 65% is formed, it does not interfere with the electrical discharge machinability. The zinc layer 4 is formed by electrogalvanizing the surface layer of the high-zinc copper-zinc alloy layer 3 to a thickness of 0.5 to 3% of the finished outer diameter. By providing the zinc layer as the outermost layer, a catalytic function for exciting the discharge phenomenon is provided to improve discharge stability. In addition, as an advantage of providing a zinc layer as the outermost layer, a brass layer having a zinc concentration of 45 to 65% is usually a α + β'phase or a β'phase at a zinc concentration of 45 to 50%, and a β '+ at a concentration of 50 to 60%. γ phase, γ phase is generated at 60 or more, which basically becomes hard and brittle, and when wire drawing is performed, cracks, cracks, etc. occur, making wire drawing difficult, but plating the surface layer We have experimentally confirmed that wire drawing is possible with a workability of about 93%.

[0006]

EXAMPLES Hereinafter, the results of the evaluation of the electric discharge machining electrode wire according to the present invention by a processing machine will be described. The electrode wires used in this example are the electrode wire having the structure of the present invention shown in FIG. 1, brass electrode wires (Cu65%, Zn35%), and brass (65/3
5) The core material is a zinc-plated electrode wire having a zinc layer on the surface and a brass (65/35) core material and the composite electrode wire having a high-zinc copper-zinc alloy layer with a zinc concentration of 40 to 47% on the surface, There are five types of composite electrode wires in which the zinc concentration of the high zinc copper-zinc alloy layer is 45 to 65% and the zinc layer is provided on the surface layer. Although the electrode wire zinc-plated on brass is used as the reference electrode wire, originally it should be confirmed the degree of contribution to the processing speed of the zinc layer in the shape without the zinc layer of the electrode wire of the present invention, This is because the electrode wire having the copper-zinc alloy layer of high zinc as the outermost layer is difficult to be drawn, as described in the previous section. Using the wire outer diameter 0.25 mm, work material SKD-11, work thickness 60 mm, and electric discharge machine SX10, based on the maximum rough machining conditions, raise the machining conditions until wire breakage occurs as shown in Table 1 below. The maximum processing speed of each wire was compared.

[0007]

[Table 1]

The results are shown in Table 2. The processing speed is expressed by the ratio when the maximum processing speed of the brass wire is 1.

[0009]

[Table 2]

The following results are obtained from the above evaluation results. 1. By providing a galvanized layer on the outermost layer, the processing speed can be increased by 4% or more. 2. From the evaluation results of the composite electrode wire and the composite electrode wire, the processing speed can be improved by increasing the zinc concentration of the high zinc copper-zinc alloy layer. 3. From the evaluation results of the electrode wire of the present invention and the composite electrode wire, by adopting a steel wire having a high-temperature tensile strength higher than that of brass as the central core material, a wire breakage occurs even if the processing conditions of a higher wire electric discharge machine are selected. It will be difficult. Therefore, according to the electrode wire for wire electric discharge machining of the present invention, which is provided with a layer for each function and has a multilayer composite structure, the machining speed can be greatly improved.

Up to now, the central core material has been a steel wire, an alloy steel wire, or an iron wire as a typical example, but basically any material having a higher high temperature tensile strength than brass can be used. Further, it goes without saying that other modified examples are also possible and are within the scope of the present invention.

Because of the above-mentioned structure, the wire electric discharge machining electrode wire 1 of the present invention is a wire excellent in high-speed machining. As a result of other reliability tests, results equivalent to those of existing products were obtained. Was given.

[0013]

As described above, according to the present invention, a steel wire having a high tensile strength at high temperature is adopted as the central core material, a brass alloy layer for improving the electric discharge machining rate is provided on the outer layer, and further the outer layer is provided with the electric discharge. The electrode wire having a multi-functional composite structure provided with a zinc layer that promotes stability can exert an excellent effect of significantly improving the processing speed, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a wire electric discharge machining electrode wire 1 of the present invention.

[Explanation of symbols]

1 Electrode wire for wire electric discharge machining of the present invention 2 Core material (steel wire, alloy steel wire or iron) 3 High-zinc copper-zinc alloy layer (zinc concentration 45 to 65)
% Copper-zinc alloy) 4 Zinc layer (zinc layer with a thickness of 0.5 to 3% of the finished outer diameter)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masakazu Yoshimoto             2-12 Shimoodachu, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 8 Oki Electric Cable Co., Ltd. (72) Inventor Yoichiro Kimoto             2-12 Shimoodachu, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 8 Oki Electric Cable Co., Ltd. (72) Inventor Kazuki Hayasaka             2-12 Shimoodachu, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 8 Oki Electric Cable Co., Ltd. F-term (reference) 3C059 AA01 AB05 DA06 DB03 DC01

Claims (3)

[Claims] 1. A steel wire, an alloy steel wire or iron as a central core material, and a high-zinc copper-zinc alloy layer having a zinc concentration of 45 to 65% is formed on the surface of the central core material. An electrode wire for wire electric discharge machining, characterized in that a zinc layer is provided on the surface of the copper-zinc alloy layer. 2. The thickness of the high-zinc copper-zinc alloy layer having a zinc concentration of 45 to 65% according to claim 1 is 10 to 20% of the finished outer diameter.
An electrode wire for wire electric discharge machining, characterized in that 3. The electrode wire for wire electric discharge machining according to claim 1, wherein the zinc layer has a thickness of 0.5 to 3% of a finished outer diameter.