JP2003039247A - Electrode wire for electric discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode wire for electric discharge machining, which can be manufactured at a low cost because of its excellent wire drawing property, and has excellent high speed machining property, and can achieve high machining accuracy. SOLUTION: In the electrode wire for electric discharge machining in which a covering layer 2 composed of Cu-Zn alloys is formed on a core wire 1, the covering layer 2 is formed with a first covering layer 3 composed of a mixed phase of an α-phase 5 and a β-phase 6 and a second covering layer 4 composed of the α-phase, and a ratio t/D of the thickness t of the second covering layer 4 to an outside diameter D is set to be 0.005-0.05.

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 electrical discharge machining, and more particularly to a coated type having an excellent working speed and a good working accuracy while having low cost due to excellent wire drawing workability. The present invention relates to an electrode wire for electric discharge machining.

[0002]

2. Description of the Related Art A Cu--Zn alloy electrode wire is used as an electrode wire for electric discharge machining. This electrode wire has excellent discharge characteristics evaluated by processing speed, processing accuracy, and the like, and further has characteristics that are advantageous in terms of cost.

Up to now, as this type of electrode wire,
Single alloy wire [Cu-35 containing 32 to 36 wt% Zn
Wt% Zn alloy (65/35 brass wire)] has been used, but in recent years, especially high-speed workability has come to be emphasized. Therefore, for example, Cu-2.0 wt% S
A covered electrode wire has been proposed in which a Cu-Zn alloy layer having a high Zn concentration is formed on a core material composed of an n alloy or Cu-0.3 wt% Sn alloy (Japanese Patent Laid-Open No. 5-339).
664).

In the above structure, as a method of forming a high-concentration Cu-Zn alloy layer on the core material, a method of forming a Zn layer on the core material and then performing a diffusion heat treatment for a long time is proposed. The electrode wire for electric discharge machining obtained thereby is evaluated as an electrode wire having excellent high-speed machinability.

[0005]

However, according to the conventional electrode wire described above, since the Zn concentration in the Cu--Zn alloy coating layer is as high as 38 to 49% by weight, the wire drawing workability is poor and the production is difficult. It has a problem of significantly increasing the cost.

Further, generally, in the case of an electrode wire formed with a brass coating layer containing a high concentration of Zn, there is a problem in processing accuracy such as surface accuracy or dimensional accuracy, although the processing speed is improved. It is generally inferior in performance to an electrode wire made of a single brass wire.

Therefore, an object of the present invention is to provide a coated type electrode wire for electric discharge machining which has a low cost based on excellent wire drawing workability, and has excellent processing speed and good processing accuracy and excellent overall characteristics. To provide.

[0008]

In order to achieve the above-mentioned object, the present invention provides an electrode wire for electric discharge machining comprising a linear body having a core material and a coating layer of a Cu--Zn alloy formed on the core material.
The coating layer is Cu-Zn that exists as a phase other than the α phase.
A first coating layer of an alloy and a second coating layer of a Cu-Zn alloy existing as an α phase formed on the first coating layer, and the thickness of the second coating layer. The ratio of t to the outer diameter D of the linear body t / D is 0.005
The present invention provides an electrode wire for electric discharge machining, which is characterized in that it has a thickness of 0.05.

The peculiarity of the present invention is that a composite coating layer is formed by a first coating layer composed of a phase other than the α phase and a second coating layer composed of the α phase, and the above construction. In, in setting a specific ratio relationship between the thickness of the second coating layer and the outer diameter of the linear body, the technical background is as follows.

In other words, the discharge characteristics (easiness of discharge) of the Cu--Zn alloy are superior to the α phase except the α phase,
Therefore, the first coating layer composed of a phase other than the α phase,
It guarantees an electric discharge machining speed that is almost proportional to the electric discharge characteristics, and thereby acts to satisfy the characteristics for high-speed machining, but on the other hand, the phases other than α phase are inferior in cold wire drawing workability. Therefore, disconnection during wire drawing is likely to occur, making it difficult to maintain productivity.

On the other hand, on the other hand, the second coating on the first coating layer
Since the constituent material of the covering layer is α phase, the excellent cold workability peculiar to this material acts on the entire wire. Therefore, as a result of the above-mentioned constitution, the formed electrode wire is excellent. High-speed workability and excellent cold wire drawing workability are provided. In particular, what is important in this structure is that the phases other than the α phase are arranged inside and the α phase is arranged outside, and this structure guarantees the wire drawing workability of the entire wire. Becomes It is impossible to obtain the same effect by the reverse configuration.

In the present invention, not only is the composite of the first and second coating layers formed, but further,
It should be noted that a ratio relationship of t / D = 0.005 to 0.05 is set between the thickness t of the second coating layer having the α phase configuration and the outer diameter D of the wire. By combining the above respective configurations with each other, an electrode wire that fulfills the purpose of the invention is constructed for the first time.

The lower limit of 0.0 at t / D shown above
05 is an important condition for preventing the second coating layer having the α-phase structure from breaking during wire drawing, thereby preventing disconnection due to the exposure of the first coating layer, while the upper limit of 0 is set. .05 is an important condition from the viewpoint of preventing the α-phase from becoming excessive and deteriorating the electric discharge machinability of the entire wire.

As the first coating layer in the present invention, α
It is preferable to form a Cu-Zn alloy in which the β phase and the β phase are mixed, and in that case, as the ratio of the β phase, the sectional area of the β phase is A and the total sectional area of the first coating layer is When B is set, it is preferable to set so that A / B = 0.5 to 0.9.

Since the first coating layer is composed of the mixed phase of α and β, the β phase which is difficult to perform cold drawing and the α phase which is easy to perform cold drawing are organically integrated with each other. Therefore, it is possible to further improve the cold drawability of the entire wire. The reason for setting the preferable lower limit value of the sectional occupation ratio by the β phase to 0.5 is 0.
If it is less than 5, the electrical discharge machining characteristics are deteriorated and the machining speed becomes insufficient. On the other hand, the reason why the upper limit value is set to 0.9 is that if it exceeds 0.9, the wire drawability is remarkably deteriorated. This is because disconnection occurs.

As the constituent material of the core material, pure copper, Cu-0.
02-0.2 wt% Zr alloy, Cu-0.15-0.2
5 wt% Sn-0.15-0.25 wt% In alloy, C
u-0.15 to 0.70 wt% Sn alloy, Cu-0.0
8-20 wt% Ag alloy, Cu-0.01-0.05 wt% Sn-0.005-0.05 wt% Mg alloy, Cu
-0.05-0.5 wt% Mg alloy, Cu-5-30 wt% Zn alloy, or Zr, Cr, Si, Mg, A
It is preferably composed of a material selected from Cu-5 to 30 wt% Zn alloy containing at least one of 1, Fe, P, Ni, Ag and Sn.

When these materials are used, it becomes possible to give high strength and high conductivity to the electrode wire,
This is advantageous in securing processing accuracy and processing speed. The lower limit value of the additive component in each copper alloy composition shown above is the limit value for maintaining high processing accuracy based on securing strength, and the upper limit value for ensuring high processing speed by maintaining conductivity. It becomes the limit value.

In the electrode wire of the present invention, it is recommended that a Zn-based third coating layer is formed on the second coating layer. As the Zn-based constituent material, it is preferable to use a Cu—Zn alloy containing 50% by weight or more of Zn, and the thickness thereof is preferably set to 1.0 to 10 μm.

When this structure is adopted, the third coating layer made rich in Zn constitutes the first coating layer α.
Since the Cu-Zn alloy of a phase other than the phase is more excellent in discharge characteristics, the presence of the third coating layer acts to greatly improve the processing accuracy such as surface accuracy and dimensional accuracy of the surface of the workpiece.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of an electrode wire for electric discharge machining according to the present invention will be described. In FIG. 1, 1 is a core material made of pure copper or the above-mentioned copper alloy, 2 is a coating layer formed on the core material 1, and is a first coating layer made of a Cu—Zn alloy existing as a phase other than the α phase. 3 and a second coating layer 4 composed of a Cu—Zn alloy existing as an α phase. t is the thickness of the second coating layer 4, D is the outer diameter of the entire wire, and these are t / D = 0.005-
It is set to have a ratio relationship of 0.05.

FIG. 2 shows another embodiment.
In the configuration of FIG. 1, the first coating layer 3 is formed of α phase 5 and β phase 6
And the ratio of the cross-sectional area A of the β phase 6 to the total cross-sectional area B of the first coating layer 3 is A / B = 0.5 to
This is an example in which the value is set to 0.9 and other configurations are the same as those in FIG.

FIG. 3 shows still another embodiment of the present invention, in which 50 is provided around the second coating layer 4 in the configuration of FIG.
This is an example in which the third coating layer 7 made of a Cu-Zn alloy containing Zn in an amount of at least wt% is formed.
It is formed to a thickness of 0 to 10 μm.

Table 1 summarizes the contents and machining characteristics of the examples and comparative examples of the electrode line for electric discharge machining based on the above construction.

[0024]

[Table 1]

A core material 1 having a diameter of 4.0 mm was manufactured by melting and casting the copper alloy of the core material shown in Table 1, and then 0.2 mm thick × 13 mm wide.
After the Zn tape of No. 1 was vertically attached and covered, a brass tape (Cu-35 wt% Zn alloy) having a thickness of 0.50 mm was also vertically attached, and the butted portion was welded to have a diameter of 5.4 mm. I made a composite line.

Next, this composite wire is subjected to wire drawing and heat treatment repeatedly, and finally, a plurality of wire drawing dies are passed through the wire to reduce its diameter, whereby each embodiment having a wire diameter of 0.25 mm. And the electrode wire for electric discharge machining in the comparative example was manufactured.

The conventional example shown in Table 1 is C
Diameter comprised of u-35 wt% Zn alloy is 0.25
mm of single electrode wire (conventional example 1) and Cu-4
An electrode wire (conventional example 2) composed of a 0 wt% Zn alloy and having a single diameter of 0.25 mm was used. Also,
In the table, the meanings of A / B and t / D are the same as described above.

According to Table 1, all of the electrode wires of Examples 1 to 14 are excellent in wire drawing workability, and the working speed is 60 to 88% higher than that of the conventional example. In addition, the processing accuracy is as good as or better than that of the conventional example having a single line structure.

This is a coating layer 2 formed on the core material 1.
Is a composite layer composed of a first coating layer 3 composed of a mixed phase of α phase 5 and β phase 6 existing as a phase other than the α phase, and a second coating layer 4 composed of the α phase. , The ratio of the thickness t of the second coating layer 4 to the outer diameter D, t /
This is caused by setting D to 0.005 to 0.05.

In addition to these, each of the core materials 1 is made of a material excellent in strength and conductivity, and the first coating layer composed of a mixed phase of α phase 5 and β phase 6 It is also effective that the ratio A / B of the cross-sectional area A of the β phase 6 and the total cross-sectional area B of the coating layer 3 in 3 is set to 0.5 to 0.9. Table 1
It is a result of.

On the other hand, on the other hand, according to an even-numbered comparative example in which the ratio t / D of the thickness t of the second coating layer 4 to the outer diameter D is set outside the scope of the present invention, either Sufficient results have not been obtained in thigh wire drawing workability. This is because the second coating layer 4 is thin and the coating was destroyed during the wire drawing process, which exposed the first coating layer 3 on the inner side and caused the disconnection.

When comparing these comparative examples with Examples 1 to 14, it is possible to confirm the significance of t / D and the meaning of setting in the present invention. In addition, according to Table 1, the shortage of t / D in the above comparative example has an unfavorable influence on the processing accuracy.

In Table 1, the comparative example having an odd number shows an unsatisfactory result at the processing speed because the ratio A / B of the cross-sectional area A of the β phase in the first coating layer 3 to the total cross-sectional area B is shown. Is less than 0.5, and the lack of electric discharge machinability due to this appears at a low machining speed. Therefore, from the above, in carrying out the present invention,
It is necessary to give due consideration to A / B.

Among Examples 1 to 14, the reason why the even-numbered machining accuracy is particularly excellent is that these electrode lines adopt the configuration of FIG. That is, the Zn-rich third coating layer 7 additionally formed on the second coating layer 4
Has an effect, and this point can be evaluated as an important effect in the present invention of the composite structure.
Needless to say, the same effect can be obtained when the coating layer 7 is formed on the second coating layer 4 in FIG.

[0035]

As described above, according to the coating type electric discharge machining electrode wire of the present invention, the first coating layer existing as a phase other than the α phase and the first coating layer are formed on the first coating layer. A
The coating layer on the core material is constituted by the composite structure of the second coating layer existing as a phase, and the ratio t / D of the thickness t of the second coating layer to the wire outer diameter D is 0.005 to 0. Since the electrode wire is configured by setting it to 05, it provides an electrode wire for electrical discharge machining that has low cost based on excellent wire drawing workability, as well as excellent high speed workability and good working accuracy. can do.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an electric discharge machining electrode wire according to the present invention.

FIG. 2 is an explanatory view showing another embodiment of the electric discharge machining electrode wire according to the present invention.

FIG. 3 is an explanatory view showing still another embodiment of the electric discharge machining electrode wire according to the present invention.

[Explanation of symbols]

1 heartwood 2 coating layer 3 First coating layer 4 Second coating layer 5 α phase 6 β phase 7 Third coating layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsunori Sawahata             4-10-1, Kawajiri-cho, Hitachi-shi, Ibaraki Hitachi             Electric Wire Co., Ltd.Toyoura Factory (72) Inventor Takahiro Sato             4-10-1, Kawajiri-cho, Hitachi-shi, Ibaraki Hitachi             Electric Wire Co., Ltd.Toyoura Factory (72) Inventor Takamitsu Kimura             4-10-1, Kawajiri-cho, Hitachi-shi, Ibaraki Hitachi             Electric Wire Co., Ltd.Toyoura Factory F term (reference) 3C059 AA01 AB05 DA06 DB03 DC02

Claims (5)

[Claims] 1. An electrode wire for electric discharge machining comprising a linear body in which a coating layer of Cu—Zn alloy is formed on a core material, wherein the coating layer is Cu—Zn present as a phase other than α phase.
A first coating layer of an alloy and a second coating layer of a Cu-Zn alloy existing as an α phase formed on the first coating layer, and the thickness of the second coating layer. The ratio of t to the outer diameter D of the linear body t / D is 0.005
An electric discharge machining electrode wire, which is configured to have a thickness of 0.05. 2. The electrode wire for electric discharge machining according to claim 1, wherein the first coating layer is made of a Cu—Zn alloy having a mixed phase of α phase and β phase. 3. The ratio β of the cross-sectional area A of the β phase to the total cross-sectional area B of the first coating layer is 0.5 to 0.9.
The electrode wire for electric discharge machining according to claim 2, wherein the electrode wire is set to. 4. The core material is pure copper, Cu-0.02-0.
2 wt% Zr alloy, Cu-0.15-0.25 wt% S
n-0.15-0.25 wt% In alloy, Cu-0.1
5 to 0.70 wt% Sn alloy, Cu-0.08 to 20 wt% Ag alloy, Cu-0.01 to 0.05 wt% Sn-
0.005-0.05 wt% Mg alloy, Cu-0.00
5 to 0.5 wt% Mg alloy, Cu-5 to 30 wt% Zn
Alloy, or Zr, Cr, Si, Mg, Al, Fe,
Cu containing at least one of P, Ni, Ag and Sn
The electrode wire for electric discharge machining according to claim 1, wherein the electrode wire is made of a material selected from a Zn alloy of -5 to 30% by weight. 5. A Cu—Zn alloy further containing 50% by weight or more of Zn is provided on the periphery of the second coating layer in an amount of 1.0 to 10 μm.
The electrode wire for electric discharge machining according to claim 1, further comprising a third coating layer formed to have a thickness of m.