JP2000225525A - Electrode wire for electric discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconcile high working speed and uniform working surface roughness so as to form electrode wire by forming a brass inner layer on a core material and forming an outer layer out of Zn-Cu alloy mainly made of Zn on this inner layer. SOLUTION: Electrode wire for electric discharge machining is constituted of a core material 1, an inner layer 2 formed on the core material 1 and made of brass and an outer layer 3 of Zn-Cu alloy which is formed on the inner layer 2 and is mainly made of Zn formed by bringing the inner layer 2 into contact with molten Zn. The brass inner layer 2 is formed based on a tube- making method welding a joint by vertically attaching a brass streak to the core material 1, for instance, and the inner layer 2 is brought into contact with molten Zn after contacting tube working into a necessary diameter is performed. The contact of the inner layer 2 and molten Zn is performed by passing the inner layer 2 through molten Zn, for instance. As a result, the inner layer 2 including Zn and pure Zn excellently react and the outer layer 3 of uniform Zn-Cu alloy which does not leave pure Zn is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode wire for electric discharge machining, and more particularly to an electrode wire for electric discharge machining capable of high-speed machining and having a good surface roughness.

[0002]

2. Description of the Related Art As a conventional electrode wire for electric discharge machining, an electrode wire made of a Cu-Zn alloy (brass) wire mainly composed of Cu is used. Further, the core material is mainly made of Cu-
An electrode wire coated with a Zn alloy (brass) as the outermost layer and an electrode wire coated with pure Zn as the outermost layer, which is excellent in arc stability during electric discharge machining, are known. Compared to the conventional electrode wires made of Cu-Zn alloy wire, these coated electrode wires have a large increase in the processing speed, but the processing accuracy has not been improved. On the other hand, the latter is characterized in that the machining accuracy and the roughness of the machined surface are high, but the machining speed is not significantly increased.

In the former case, it is possible to further increase the processing speed by increasing the Zn concentration of the outer layer, but on the other hand, as the Zn concentration increases to 43 to 45%, the roughness of the finished surface increases, It is not preferable because the accuracy is deteriorated. Also, in the latter case, it is conceivable to improve the processing speed by increasing the thickness of the pure Zn layer. However, increasing the thickness of the pure Zn layer having a lower strength lowers the strength of the electrode wire and further increases the flame. It is not preferable because a ball is formed at the time of cutting to make it difficult to pass a die.

[0004] In particular, in the latter case, pure Z during electric discharge machining is used.
Since the evaporative wear of n is large and, therefore, if the pure Zn layer is made thicker, the input side and the output side of the electrode wire are shifted and the processed surface becomes tapered, which also limits the increase in thickness.
Usually, about 10 μm is the maximum thickness of the pure Zn layer. Therefore, a large increase in processing speed cannot be expected. As described above, in these electrode wires, it is difficult to achieve both processing accuracy, processing surface roughness, and processing speed, and therefore, it is the fact that one of the characteristics is selected according to the processing purpose. .

[0005] Also, from a manufacturing point of view, for example, the brass layer in the former is usually formed by coating a copper layer with pure Zn and subjecting it to a long-time heat diffusion treatment. Therefore, the production speed is slow and inefficient,
Therefore, it is disadvantageous in terms of cost and also has quality instability due to difficulty in setting heating conditions for diffusion.

As an alternative to these conventional products, which have problems in processing speed, processing accuracy, manufacturing cost, etc., a high-strength core material is coated with a good conductive material such as Cu, and the outermost layer is made of Zn or Electrode wires plated with a Cd-based alloy layer have been proposed.

In this electrode wire, the alloy layer has a thickness of 1 to 25 μm in view of the intensity and duration of electric discharge during electric discharge machining.
m. The parameters of electric discharge machining are that the good conductive material is exposed due to the consumption of the alloy layer, the electric discharge characteristics are reduced and the machining speed is adversely affected, or the machining surface is roughened by attaching to the workpiece. Is adjusted within the range of consumption of the alloy layer so that there is no loss.

[0008] The idea of this electrode wire is to secure high-speed workability with a good conductive material having a large current density, and to secure processing accuracy with a high-strength core material. The electrode wire for electric discharge machining provided is constituted.

[0009]

However, according to the conventional electrode wire for electric discharge machining, since the alloy layer is formed by plating, the concentration of the alloy component tends to be non-uniform.
Furthermore, the processing speed and the roughness of the processing surface are not as high as the high processing speed of the electrode wire having the outer layer made of brass or the roughness of the processing surface of the electrode wire having the outer layer made of pure Zn. .

Accordingly, an object of the present invention is to provide a high-speed workability equivalent to that of an electrode wire using brass for the outer layer and a roughness characteristic of a processed surface equivalent to that of an electrode wire using pure Zn for the outer layer. , Furthermore, it does not require heat diffusion treatment,
An object of the present invention is to provide an electric discharge machining electrode wire having a uniform concentration distribution of components in the formed alloy layer.

[0011]

In order to achieve the above object, the present invention provides a core material, an inner layer formed on the core material and made of brass, and formed on the inner layer, An object of the present invention is to provide an electrode wire for electric discharge machining, characterized in that the inner layer is made of an outer layer of a Zn-Cu alloy mainly composed of Zn formed by bringing the inner layer into contact with molten Zn.

As the constituent materials of the above-mentioned core material, Cu, C
A u-alloy or steel is preferable, and its constitutional form may be either a simple substance or a composite. The brass constituting the inner layer preferably has an α phase or a mixed crystal structure of an α phase and a β phase so that cold working is possible.

The inner layer of brass is formed based on, for example, a pipe forming method in which a brass strip is vertically attached to a core material and a joint is welded, and after being reduced in diameter to a required diameter, is brought into contact with molten Zn. . The contact between the inner layer and the molten Zn is performed, for example, by passing the inner layer through the molten Zn.
And the pure Zn react well with each other to form a homogeneous outer layer of a Zn—Cu alloy in which pure Zn does not remain.
After the outer layer is formed, wire drawing is performed to form an electric discharge machining electrode wire having a predetermined size.

The outer layer may be constituted by a single Zn-Cu alloy layer, or may be constituted by a plurality of Zn-Cu alloy layers whose Cu concentration decreases toward the outside. It is preferable that the outer layer be formed of a plurality of such Zn-Cu alloy layers, since the adhesion to the workpiece is reduced.

In the electrode wire of the present invention, since the inner layer is made of brass, when the outer layer is consumed and the inner layer is exposed, the discharge characteristics are not deteriorated and the machining speed is not adversely affected. Since the inner layer does not adhere to the workpiece, the processed surface is not roughened.

Further, since the inner layer is formed by directly covering the brass, the heat diffusion treatment is unnecessary, and therefore, the inner layer can be formed efficiently. In addition, since the outer layer of the Zn-Cu alloy mainly composed of Zn is formed by bringing the inner layer of brass into contact with the molten Zn, the heat diffusion process is not necessary, and the electrode wire is low in cost as a whole. It can be.

[0017]

Next, an embodiment of an electrode wire for electric discharge machining according to the present invention will be described.

EXAMPLE 1 0.2% by weight of Sn and 0.2% by weight of In
4.1, the balance being composed of an alloy consisting of Cu
A 0.86 mm thick brass strip (tape) composed of 35% by weight of Zn and the balance of Cu is vertically attached to a core material having a diameter of 25 mm to weld a seam. A base material having a diameter of 5.6 mm was manufactured.

Next, the base material is subjected to heat treatment, wire drawing, and heat treatment to obtain an intermediate material having an outer diameter of 1.2 mm.
mm, a predetermined electrode wire for electric discharge machining was obtained.

[0019]

Example 2 0.2% by weight of Sn and 0.2% by weight of In
4.1, the balance being composed of an alloy consisting of Cu
A 0.86 mm thick brass tape consisting of 35% by weight of Zn and the balance of Cu is welded on a core material having a diameter of 35 mm, and the joint is welded. A 5.6 mm base material was obtained.

Next, the base material is subjected to heat treatment, wire drawing, and heat treatment to form an intermediate material having an outer diameter of 2.0 mm, and then pass through a molten Zn plating tank. A predetermined electrode wire for electric discharge machining was obtained by drawing to 0.25 mm.

FIG. 1 (a) shows a cross section of the electrode wire for electric discharge machining manufactured according to Example 1, and shows 0.2% by weight.
An inner layer 2 of brass and an outer layer 3 of a Zn-Cu alloy mainly composed of Zn are sequentially formed on a core material 1 of a Cu alloy containing Sn and In. The outer layer 3 has a plurality of Zn—Cu alloy layers 3 a, 3 b, and 3 c whose Cu concentration becomes lower toward the outside.
It is constituted by.

FIG. 1B shows a micrograph of a cross section of the electrode wire. The exterior 3 has 34.51% by weight of C
It is roughly divided into a lower layer portion of a Zn-Cu alloy containing u, an intermediate portion containing 15.32% by weight of Cu, and an upper layer portion containing 3.38% by weight of Cu.

FIGS. 2A and 2B show a sectional structure of the electrode wire for electric discharge machining obtained in Example 2. FIG. Zn-C containing 34.51% by weight of Cu is placed on a core 1 made of a Cu alloy containing 0.2% by weight of Sn and In.
An outer layer 3 made of a u alloy is formed.

[0024]

Comparative Example 1 An electrode wire composed of a single wire of brass containing 40% by weight of Zn was prepared.

Comparative Example 2 In FIG. 2, an electrode wire was prepared in which the outer layer 3 was composed of an alloy layer containing 43% by weight of Zn and the balance being Cu.

[0025]

Comparative Example 3 An inner layer of brass containing 35% by weight of Zn was formed on a core material composed of a Cu alloy mainly containing Cu containing 0.2% by weight of Sn and In. An electrode wire on which an outer layer of pure Zn was formed was prepared.

The brass layer in this electrode wire is formed by providing a Zn layer on a Cu layer and then performing a heat diffusion treatment. In this method, the surface of the brass layer has a pure surface. The Zn layer remains.

Table 1 shows the characteristics of the electrode wires for electric discharge machining according to the above-mentioned examples and comparative examples. In Table 1, the characteristics are indicated by an index when the characteristics of Comparative Example 1 are set to 100.

[0028]

[Table 1]

According to Table 1, the electrode wires according to the present embodiment are:
It shows the same level of processing speed as Comparative Example 2 where a high processing speed is evaluated, and also shows the same result as Comparative Example 3 where excellent evaluation is given in the roughness of the processed surface. Compared to Comparative Examples 2 and 3, which show biased characteristics,
The effect of the present invention that achieves both the processing speed and the processing roughness characteristics is obvious.

[0030]

As described above, according to the electrode wire for electric discharge machining of the present invention, an inner layer of brass is formed on a core material, and Z
Since the outer layer is formed of a Zn-Cu alloy mainly composed of n, it is possible to provide an excellent electrode wire for electric discharge machining which achieves both a machining speed and a machined surface roughness.

The inner layer of brass is formed by coating the brass itself, and the outer layer is formed by contacting the inner layer of brass with molten Zn. Is uniform, and since neither layer requires a heat-diffusion treatment, a low-cost electrode wire can be obtained. Of course, there is no quality instability caused by the heat diffusion treatment, which has been a problem in the conventional electrode wire.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of an electrode wire for electric discharge machining according to the present invention, wherein (a) is a cross-sectional view and (b) is a micrograph.

FIGS. 2A and 2B are explanatory views showing another embodiment of the electrode wire for electric discharge machining according to the present invention, wherein FIG. 2A is a cross-sectional view and FIG.

[Explanation of symbols]

Reference Signs List 1 core material 2 inner layer 3 outer layer 3a, 3b, 3c Zn-Cu alloy layers having different Zn concentrations

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromitsu Kuroda 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Power Systems Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Masato Watanabe 5 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1-1, Hitachi Power Systems Co., Ltd. (72) Inventor Takahiro Sato 4-10-1, Kawajiri-cho, Hitachi City, Ibaraki Prefecture Inside the Toyoura Plant, Hitachi Cable Co., Ltd. (72) Inventor Katsunori Sawahata Hitachi, Ibaraki Prefecture 4-10-1, Kawajiri-cho, Hitachi Cable Co., Ltd. Toyoura Plant (72) Inventor Hideo Kono 4-1-1, Kawajiri-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Cable Co., Ltd. Toyoura Plant 3C059 AA01 DB03 DC01 DC02

Claims (4)

[Claims] 1. A core material, an inner layer formed on the core material and made of brass, and Zn formed on the inner layer and contacting the inner layer with molten Zn. An electrode wire for electric discharge machining, comprising an outer layer of a main Zn-Cu alloy. 2. The electrode wire for electric discharge machining according to claim 1, wherein said core material is made of Cu, a Cu alloy, or steel. 3. The electrode wire for electrical discharge machining according to claim 1, wherein the inner layer is made of brass having an α phase or brass having a mixed crystal structure of an α phase and a β phase. 4. The electrode wire for electric discharge machining according to claim 1, wherein said outer layer is constituted by a plurality of Zn—Cu alloy layers whose Cu concentration decreases toward the outside.