JP3948166B2 - Electrode wire for electric discharge machining - Google Patents

Description

【００３５】
次に、実施例１，２および比較例１の電極線における放電加工評価、平均面粗度（μｍ）の評価を行った。その評価結果を同じく表１に示す。
【００３６】
放電加工評価は、放電加工試験機（ソディック製、ＡＰ−２００）を用いて板厚１０ｍｍの被加工物（ＪＩＳ ＫＤ−２０）を加工した時の放電加工速度を測定したものである。尚、加工速度は、比較例１の加工速度を１．００とした時の相対比である。また、平均面粗度は、被加工物の加工面における平均表面粗さ（凹凸の平均深さ）である。
【００３７】
この結果、実施例１，２の電極線においては、比較例１の電極線と比較して、加工速度がそれぞれ１２％、１０％も上昇していた。また、比較例１の電極線の平均面粗度が０．７０μｍであったのに対して、実施例１，２の電極線の平均面粗度は０．５９μｍ、０．６０μｍであり、平均面粗度が約１５％も小さくなっており、加工面がより平滑になっている。
【００３８】
すなわち、本発明の電極線である実施例１，２の電極線においては、従来の極細電極線である比較例１の電極線と比較して、放電加工速度および放電加工精度が向上するという優れた効果を認めることができる。
【００３９】
【発明の効果】
以上要するに本発明によれば、従来の極細電極線よりも、速い加工速度で放電加工を行うことができると共に、加工精度が良好な放電加工用電極線が得られるという優れた効果を発揮する。
【図面の簡単な説明】
【図１】 本発明の放電加工用電極線１の横断面図である。
【図２】 他の実施の形態の放電加工用電極線１１の横断面図である。
【符号の説明】
１，１１ 電極線（放電加工用電極線）
２ 心線
３ Ｃｕ−Ｚｎ合金被覆層（被覆層）
４ Ｚｎ層
Ｄ 電極線の外径
ｔ 被覆層の層厚[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode wire for electric discharge machining, and particularly to an electrode wire for coated electric discharge machining having an outer diameter of 0.07 mm or less.
[0002]
[Prior art]
As a commonly used electrode wire for electric discharge machining (hereinafter referred to as an electrode wire), there is a Cu-35Zn alloy wire (65/35 brass wire) made of a Cu-35Zn alloy having a Zn concentration of 32 to 36 wt%. is there.
[0003]
By the way, it is generally said that the temperature of the electrode wire during electric discharge machining is increased to 200 to 400 ° C., and a high temperature heat load is applied. Further, during electric discharge machining, the electrode wire is also loaded with tension for improving the machining speed and machining accuracy. For this reason, the electrode wire is required to have high high-temperature tensile strength.
[0004]
The above-described brass wire has a tensile strength at room temperature about twice that of the copper wire, but the tensile strength at a high temperature of about 300 ° C. is slightly higher than that of the copper wire. For this reason, in the electrode wire which consists of a brass wire, if the load tension | tensile_strength is raised and a processing speed is raised in order to improve productivity, a disconnection will arise.
[0005]
In recent years, it has been desired to improve the processing speed of electrode wires from the viewpoint of productivity improvement. For example, Cu-2.0 wt% Sn, Cu-0.3 wt% Sn, Cu-13 wt% Zn, Cu-0.6 wt% Ag A coated electrode wire having a Cu alloy wire made of Cu-4.0 wt% Zn-0.3 wt% Sn as a core wire and a high Zn concentration Cu-Zn alloy coating layer provided on the outer periphery of the core wire has been proposed. Yes.
[0006]
In addition, from the viewpoint of improving processing accuracy, there is a demand for further thinning of the electrode wire, in particular, an ultrafine electrode wire having an outer diameter of 0.07 mm or less. For example, a single wire made of W or Mo having a high temperature strength (W Recently, there has been proposed a composite wire (brass-coated steel wire) in which a Cu-Zn alloy coating layer is provided on the outer periphery of a core wire made of a steel wire.
[0007]
[Problems to be solved by the invention]
However, although the above-described coated electrode wire uses a Cu alloy having a high tensile strength as the core wire, the tensile strength is not sufficient, and the electrical conductivity is reduced by the increase in the tensile strength.
[0008]
Moreover, since the conventional ultrafine electrode wire such as the W wire, Mo wire or brass steel wire mentioned above gives priority to the high temperature tensile strength, there is a problem that the wire drawing workability at normal temperature or low temperature is not good, or the conductivity is low. It has a problem of low discharge characteristics and the like.
[0009]
Accordingly, the present invention provides an electrode wire for electric discharge machining that solves the above-mentioned problems, has an outer diameter of 0.07 mm or less, high-temperature tensile strength, good wire drawing workability, and high conductivity. is there.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is directed to an electric discharge machining electrode wire having an outer diameter of 0.07 mm or less, Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy or Cu-0.02-0.2 On the outer periphery of the core wire made of wt% Zr alloy, Cu having a single-phase structure of α-phase with a ratio (t / D) of the layer thickness t to the outer diameter D of the electrode wire in the range of 0.1 to 0.2 -A Zn alloy coating layer is provided.
[0011]
The invention of claim 2 is the electrode wire for electric discharge machining according to claim 1, wherein the Cu-Zn alloy has a Zn concentration of 32 to 38 wt%.
[0012]
A third aspect of the present invention is the electrode wire for electric discharge machining according to any one of the first to second aspects, wherein a Zn layer is provided on the outer periphery of the coating layer.
[0013]
The reason for limiting the above numerical range will be described below.
[0014]
The reason why the core material is a Cu alloy is that it is excellent in straightness and easy to handle with a processing machine. In particular, Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy or Cu-0.02-0.2 wt% Zr alloy was selected as the Cu alloy because of its excellent conductivity, tensile strength, and heat resistance. Because it is.
[0015]
In addition, the reason why the Zn concentration of the coating layer of the Cu—Zn alloy is limited to the range of 32 to 38 wt% is that the Cu—Zn alloy can have an α-phase single-phase structure in this range. Within the range of the α phase, the tensile strength and hardness increase as the Zn concentration increases, but have sufficient elongation (50% or more) for cold working. Therefore, manufacture by wire drawing etc. becomes easy. Here, the Zn concentration is preferably 32 to 36 wt% which is the Zn concentration range of a Cu-35Zn alloy (65/35 brass) known as a general-purpose product. Of course, this Cu-35Zn alloy has an α-phase single-phase structure and can be easily cold-worked and is a general-purpose product, so that it is excellent in terms of market availability and economy.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0017]
A cross-sectional view of the electrode wire for electric discharge machining according to the present invention is shown in FIG.
[0018]
As shown in FIG. 1, the electrode wire 1 of the present invention has an outer diameter of 0.07 mm or less and a Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy (or Cu-0.02-0.2 wt% Zr). A coating layer of Cu-Zn alloy, in particular, in the ratio of the layer thickness t to the outer diameter D of the electrode wire (t / D) in the range of 0.1 to 0.2 on the outer periphery of the core wire 2 made of an alloy), A Cu—Zn alloy coating layer 3 made of an α-phase single-phase structure is provided.
[0019]
If the layer thickness t of the coating layer 3 is too thin with respect to the outer diameter D of the electrode wire 1, the tensile strength of the electrode wire 1 is reduced and breakage is likely to occur during electric discharge machining. On the contrary, if the layer thickness t of the coating layer 3 becomes too thick, the conductivity of the electrode wire 1 is lowered and the discharge characteristics are deteriorated, so t / D is set to 0.2 or less.
[0020]
In the coated electrode wire, there is a relationship between the tensile strength and the electrical conductivity of the Cu alloy constituting the core wire that the electrical conductivity decreases when the tensile strength is improved. Therefore, the core wire 2 of the electrode wire 1 has a balance between tensile strength and electrical conductivity, and has both high tensile strength and high electrical conductivity.
[0021]
Since the core wire 2 has a high electrical conductivity, the discharge characteristics and thermal conductivity of the electrode wire 1 are improved, the processing speed of the electrode wire 1 can be increased, and the electrode wire 1 at the time of electric discharge machining is also provided. Temperature rise can be suppressed. Moreover, since the core wire 2 has good heat resistance in combination with good thermal conductivity, the degree of decrease in tensile strength when the temperature of the electrode wire 1 is increased (during electric discharge machining). Since the core wire 2 is small and the tensile strength itself is high, the frequency of disconnection of the electrode wire 1 is low even if the machining current is increased.
[0022]
Further, since the Cu—Zn alloy coating layer 3 of the electrode wire 1 is a Cu—Zn alloy composed of an α-phase single phase structure, a Cu structure composed of a mixed structure of α phase and β phase or a β phase single phase structure. -Although the electrical conductivity and the tensile strength are inferior to those of the Zn alloy, the drawing rate (elongation rate) at room temperature or low temperature is large. Here, since the core wire 2 is a Cu alloy, the workability at normal temperature or low temperature is good, and the workability at normal temperature or low temperature of the Cu—Zn alloy coating layer 3 is also good. Can be manufactured by cold working.
[0023]
That is, according to the present invention, high temperature tensile strength is high by coating the outer periphery of the core wire 2 with the Cu—Zn alloy coating layer 3 in the range of t / D of 0.1 to 0.2, and It is possible to obtain an ultrathin electrode wire 1 having a significantly higher electrical conductivity than the conventional ultrathin electrode wire.
For this reason, the electric discharge machining can be performed at a higher machining speed than the conventional ultrafine electrode wire, the frequency of disconnection accompanying the electric discharge machining is low, and the machining accuracy is also good.
[0024]
Next, another embodiment of the present invention will be described with reference to the accompanying drawings.
[0025]
FIG. 2 shows a cross-sectional view of the electric discharge machining electrode wire of the present embodiment. In addition, the same code | symbol is attached | subjected to the member similar to FIG.
[0026]
As shown in FIG. 2, the electrode wire 11 of the present embodiment has an outer diameter of 0.07 mm or less, and a Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy (or Cu-0.02-0.2 wt). % Zr alloy) on the outer periphery of the core wire 2 with a ratio of the layer thickness t to the outer diameter D of the electrode wire (t / D) in the range of 0.1 to 0.2, a coating layer of Cu—Zn alloy, In particular, a Cu—Zn alloy coating layer 3 having a single phase structure of α phase is provided, and a Zn layer 4 is provided on the outer periphery of the Cu—Zn alloy coating layer 3.
[0027]
The layer thickness of the Zn layer 4 is not particularly limited. However, by performing a heat treatment at the end of the manufacturing process of the electrode wire 11, Zn in the Zn layer 4 is dissolved in Cu—Zn of the Cu—Zn alloy coating layer 3, and an α phase is formed on the outermost peripheral portion of the electrode wire 11. Cu—Zn alloy coating layer 5 having a mixed structure of γ and β phase or a single phase structure of β phase is formed. Here, the Cu—Zn alloy coating layer 5 has the maximum tensile strength when the Zn content is about 43 wt%.
In addition, when the Zn content is 38 to 50 wt%, the Cu—Zn alloy coating layer 5 has a higher conductivity as the Zn content increases. Therefore, it is desirable to adjust the layer thickness of the Zn layer 4 so that the Zn content in the Cu—Zn alloy coating layer 5 is 38 to 48 wt% (preferably 39 to 47 wt%). -5.0 μm is particularly desirable.
[0028]
It should be noted that the electrode wire 11 of the present embodiment is the electrode of the present invention except that the number of manufacturing steps of the electrode wire 11 of the present embodiment is greater than that of the electrode wire 1 of the present invention shown in FIG. The same effect as the wire 1 is exhibited.
[0029]
【Example】
Example 1
A core wire having an outer diameter of 7.1 mm made of Cu-0.19 wt% Sn-0.20 wt% In was inserted into a Cu-Zn alloy pipe made of Cu-35 wt% Zn, having an outer diameter of 10 mm and a tube thickness of 1.2 mm. A composite tube is formed. In addition, as a Cu-Zn alloy tube, what was produced using normal extrusion is used.
[0030]
The composite pipe is subjected to wire drawing to form a φ7.9 mm composite wire, and then heat treatment for softening is performed. Finally, wire drawing is applied to the composite wire to produce an electrode wire having a φ0.07 mm, Cu—Zn alloy coating layer thickness of 8.8 μm.
[0031]
(Example 2)
An electrode wire of φ0.07 mm and a Cu—Zn alloy coating layer thickness of 8.8 μm was prepared in the same manner as in Example 1 except that a core wire made of Cu-0.16 wt% Zr and having an outer diameter of 7.1 mm was used. To do.
[0032]
(Comparative Example 1)
An electrode wire having a φ0.07 mm and a Cu—Zn alloy coating layer thickness of 8.8 μm is produced basically in the same manner as in Example 1 except that a steel wire having an outer diameter of 7.1 mm is used as the core wire. At this time, it was found that the core wire made of a steel wire did not have good drawability, and it was difficult to manufacture the electrode wire.
[0033]
Table 1 shows the specifications of the core wires in the electrode wires of Examples 1 and 2 and Comparative Example 1.
[0034]
[Table 1]

[0035]
Next, electrical discharge machining evaluation and average surface roughness (μm) of the electrode wires of Examples 1 and 2 and Comparative Example 1 were evaluated. The evaluation results are also shown in Table 1.
[0036]
The electric discharge machining evaluation is a measurement of an electric discharge machining speed when a workpiece (JIS KD-20) having a thickness of 10 mm is machined using an electric discharge machining tester (AP-200, manufactured by Sodick). The processing speed is a relative ratio when the processing speed of Comparative Example 1 is 1.00. The average surface roughness is an average surface roughness (average depth of irregularities) on the processed surface of the workpiece.
[0037]
As a result, in the electrode wires of Examples 1 and 2, the machining speeds increased by 12% and 10%, respectively, as compared with the electrode wire of Comparative Example 1. Moreover, while the average surface roughness of the electrode wire of Comparative Example 1 was 0.70 μm, the average surface roughness of the electrode wires of Examples 1 and 2 was 0.59 μm and 0.60 μm. The surface roughness is about 15% smaller, and the processed surface is smoother.
[0038]
That is, in the electrode wires of Examples 1 and 2 which are the electrode wires of the present invention, the electrical discharge speed and the accuracy of electrical discharge machining are improved as compared with the electrode wire of Comparative Example 1 which is a conventional ultrafine electrode wire. The effect can be recognized.
[0039]
【The invention's effect】
In short, according to the present invention, the electric discharge machining can be performed at a higher machining speed than that of the conventional ultrafine electrode wire, and an excellent effect is obtained that an electric discharge machining electrode wire with good machining accuracy can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electric discharge machining electrode wire 1 of the present invention.
FIG. 2 is a cross-sectional view of an electric discharge machining electrode wire 11 according to another embodiment.
[Explanation of symbols]
1,11 electrode wire (electrode wire for electric discharge machining)
2 Core wire 3 Cu—Zn alloy coating layer (coating layer)
4 Zn layer D Outer diameter of electrode wire t Layer thickness of coating layer

Claims (3)

  In an electrode wire for electric discharge machining having an outer diameter of 0.07 mm or less, an electrode wire is formed on the outer periphery of a core wire made of a Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy or a Cu-0.02-0.2 wt% Zr alloy. The ratio of the layer thickness t to the outer diameter D (t / D) is in the range of 0.1 to 0.2, and a coating layer of a Cu—Zn alloy having a single phase structure of α phase is provided. Electrode wire for electric discharge machining. The electrode wire for electric discharge machining according to claim 1, wherein the Cu-Zn alloy has a Zn concentration of 32 to 38 wt%. Electrical discharge machining electrode wire according to any one claims 1 to 2 provided with a Zn layer on the outer periphery of the coating layer.

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