KR20200049183A - Electric discharge machining wire electrode and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an electrode wire for electric discharge machining and a method for manufacturing the same. The electrode wire has a structure in which a coating layer is formed on the surface of a core wire, wherein the coating layer is an alloy layer of nickel and zinc. The coating layer can be formed by the steps of: forming a nickel layer on the surface of the core wire; forming a zinc layer on the surface of the nickel layer; and forming an alloy layer of nickel and zinc through diffusion heat treatment. By forming the nickel layer having a high melting point and high hardness in the step before forming the zinc layer and then applying diffusion heat treatment to the nickel layer so as to form a tightly bonded nickel-zinc alloy layer on the core wire surface, the electrode wire and the method for manufacturing the same of the present invention are capable of withstanding high heat generated during electric discharge machining, increasing an applied voltage, and improving a flushing effect, an automatic wiring rate by surface hardening, and a function of keeping a mold surface clean. That is, it is possible to significantly increase the processing speed by improving tensile strength compared to a conventional simple brass or zinc coated brass electrode wire. In addition, the electrode wire of the present invention is advantageous for automating and unmanning discharge processing by improving the tensile strength and straightness and improving the automatic wiring rate. In addition, the generation of dust is suppressed through the refinement and stabilization of the nickel-zinc alloy layer as a coating layer, and the tensile strength is improved to facilitate the insertion of the electrode wire into the small hole of a work, thereby improving overall workability.

Description

Electrode wire for electric discharge processing and its manufacturing method {ELECTRIC DISCHARGE MACHINING WIRE ELECTRODE AND MANUFACTURING METHOD THEREOF}

The present invention relates to an electrode wire for electric discharge processing and a method for manufacturing the same, and more particularly, to an electrode wire for electric discharge processing having a coating layer formed on the core wire and a method for manufacturing the same.

Electric Discharge Machining (EDM) is a machining method that cuts or cuts a workpiece using sparks generated by generating discharge between the traveling electrode wire and the workpiece. The electrode wire for electric discharge machining is consumable, and this electric discharge machining technique has an absolute influence on the machining of difficult-to-cut hard materials and high-hardness heat-treated mold materials and the asymmetric shape mold processing technology. In accordance with the development of industrial technology, the mold technology has also been developed, and the electrode wire for discharge processing has been continuously developed to improve the precision of the mold and the processing speed.

In the conventional electrode line for electric discharge processing, silver (Ag) or copper (Cu) having high electrical conductivity has a large discharge effect, but zinc (Zn) having high evaporation and explosive power is used to rapidly discharge discharge marks in which the work pieces generated during discharge processing are rapidly discharged. Contained brass electrode wire is mainly used. These brass electrode wires increase the content of zinc (Zn) to improve the electrical conductivity, strength and processing speed, but if the content of zinc increases, the cold workability of the electrode wire decreases, so zinc (Zn) of 40 wt% or more by weight is used. It does not produce electrode wires.

On the other hand, instead of constructing an electrode wire from a conventional single material, an electrode wire in the form of a core wire and forming a coating layer having a thickness of several micrometers on its surface is disclosed. For example, electrode wires produced by using brass as a core wire and diffusing heat treatment after electroplating or hot dip galvanizing zinc on the surface thereof are typical. However, since the coating layer of such an electrode wire is composed of a pure galvanized layer or a diffusion layer, the tensile strength is insufficient and the breakage tends to occur when the applied contact pressure increases, resulting in poor processing speed and workability, and deformation due to aging hardening of the connective tissue between copper and zinc. Due to the decrease in straightness due to the lowering of the automatic connection rate, there is a limitation in high precision and unmanned processing.

-Japanese Patent Publication No. 2005-512826 -Japanese Patent Publication No. 2005-230992

An object of the present invention is to improve the tensile strength and straightness and suppress the generation of dust, to provide an electrode wire for electrical discharge machining and a method for manufacturing the same, which can improve processing speed, machining precision, automatic connection rate and workability during electrical discharge machining. will be.

The present invention has been made as a result of earnest examination in order to solve the above-described problems, the subject matter of which is the same as described in the claims.

(1) An electrode wire for electric discharge machining in which a coating layer is formed on the surface of the core wire, wherein the coating layer is an alloy layer of nickel and zinc.

(2) The electrode wire for electric discharge machining according to (1), wherein the core wire is brass.

(3) The electrode wire for electric discharge machining according to (1), wherein the weight ratio of nickel to zinc is 2: 8 to 3: 7.

(4) A method for manufacturing an electrode wire for electric discharge processing, which is produced by reducing the thickness after forming a coating layer on the surface of the core wire, wherein the formation of the coating layer comprises: forming a nickel layer on the surface of the core wire; Forming a zinc layer on the nickel surface; And forming an alloy layer of nickel and zinc through diffusion heat treatment.

(5) The method of manufacturing an electrode wire for electric discharge machining according to (4), wherein the formation of the nickel layer is a plating method.

(6) The method of manufacturing an electrode wire for electric discharge machining according to (4), wherein the formation of the zinc layer is a plating method.

(7) The method of manufacturing the electrode wire for electric discharge machining according to (4), wherein the heat treatment is performed at a temperature of 420 to 450 ° C for 6 hours or more.

(8) The method of manufacturing the electrode wire for discharge processing according to (4), wherein the nickel layer and the zinc layer are formed in a weight ratio of 2: 8 to 3: 7.

(9) The method of manufacturing an electrode wire for discharge processing according to (4), wherein the nickel layer has a thickness of 2 to 4 μm.

(10) The thickness of the zinc layer is 6 ~ 12㎛ characterized in that the electrode wire manufacturing method of the discharge processing, characterized in that (4).

(11) A method of manufacturing an electrode wire for discharge processing according to (4), further comprising a step of tempering after reduction.

The electrode wire of the present invention and a method of manufacturing the same are formed by forming a nickel layer having a high melting point and high hardness at a stage before forming a zinc layer, followed by diffusion heat treatment to form a densely bonded nickel-zinc alloy layer on the surface of the core wire, resulting in high generation during discharge processing. It can withstand heat, increase the applied voltage, improve the flushing effect and improve the automatic connection rate by surface hardening and the ability to keep the mold surface clean. That is, it is possible to significantly increase the processing speed by improving the tensile strength compared to a conventional simple brass or zinc coated brass electrode wire. In addition, the electrode wire of the present invention is advantageous for automating and unmanning discharge processing by improving the tensile strength and straightness and improving the automatic connection rate. In addition, dust generation is suppressed by miniaturization stabilization for the nickel-zinc alloy layer as a coating layer, and tensile strength is improved, so that it is easy to insert an electrode line into a small hole of a work piece, thereby improving overall workability.

1 is a cross-sectional structure diagram of an electrode wire for electric discharge machining according to the present invention.
Figure 2 is a process diagram of a method for manufacturing an electrode wire for electrical discharge machining according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent reference numbers are assigned to the same or equivalent materials. In addition, throughout the specification, when a certain part 'includes' a certain component, this means that unless otherwise stated, other components are not excluded, and other components may be further included. In addition, when a component is provided, provided or included 'optionally', it is not an essential component for the solution of the present invention, but can be arbitrarily adopted with such a solution and consistency. it means.

1 shows a cross-sectional structure diagram of an electrode line for discharge processing according to the present invention (hereinafter abbreviated as 'electrode line') , and FIG. 2 shows a flowchart for a method of manufacturing an electrode line according to the present invention.

The electrode wire has a structure in which a coating layer is formed on the surface of the core wire, and is basically prepared by providing a core wire (S10), and forming a coating layer on the surface of the core wire (S22 to S26), or reducing it (S30). In this case, the formation of the coating layer is a step of forming a nickel layer on the surface of the core wire (S22); Forming a zinc layer on the nickel surface (S24); And forming an alloy layer of nickel and zinc through diffusion heat treatment (S26).

Copper may be used as an EDM wire material for general electric discharge machining as the core wire base material of the electrode wire, and preferably brass may be used as an alloy of copper (Cu) and zinc (Zn). As such a brass, for example, brass containing 35 wt% or 37 wt% Zn by weight may be used.

The coating layer is an alloy layer of nickel and zinc, and is formed by sequentially forming a nickel layer and a zinc layer on the surface of the core wire and then diffusing heat. Basically, the nickel layer of the coating layer improves the adhesion with a core wire base material such as brass, which is a kind of copper alloy, and the zinc layer of the coating layer has a high affinity with the nickel layer, so that the middle of the core layer and the outermost layer zinc layer The presence of a nickel layer has the effect of improving the overall adhesion of the coating layer composed of the nickel layer and the zinc layer.

Specifically, the nickel layer may reduce the amount of de-zinc generated from the brass busbar and the zinc layer, which are core wires during diffusion heat treatment. In other words, after the zinc layer is directly formed on the brass busbar, during diffusion treatment, diffusion occurs between the brass and the zinc atoms to obtain a brass plated layer of a new composition with a high zinc content at the root of the final electrode wire. Depending on the holding time, de-zinc phenomenon in which zinc evaporates from the brass and galvanized layers may occur. However, as in the present invention, the presence of a nickel plating layer in the middle prevents dezincification due to the formation of a copper-nickel-zinc alloy having excellent interatomic affinity and obtains a healthy plating layer with high adhesion of the plating layer. Therefore, in the present invention, it can be seen that it has a relatively high adhesion to a plated layer of a brass wire without a nickel layer, and this effect brings about an improvement in tensile strength because of its high resistance to shear stress applied to the plated layer during the tensile test. In this case, if the nickel layer and the zinc layer are too thin, the adhesion with the core wire is good, but the diffusion of copper atoms from the core wire is faster, and the surface of the electrode wire is composed of an alloy of copper / zinc / nickel, which is similar to the existing simple zinc plated electrode wire. It becomes a wire. Conversely, if the nickel content is high, the diffusion movement speed of the core and zinc layers is low, so the fluxing effect during wire discharge processing is low, and the effect of improving the processing speed, which is the object of the present invention, cannot be expected.

In addition, the brass busbar constituting the core wire of the electrode wire is present in the α phase, the *? * Phase, and the γ phase depending on the zinc content, and the higher the zinc content, the higher the hardness, susceptible to cracking, and easily de-zinc occurs. , In the present invention, the addition of the third nickel layer to the coating layer also has an advantage in that zinc equivalent is relatively reduced due to solid solution with copper. That is, by adding nickel, less cracking of the plating layer due to high zinc content occurs during fresh processing or diffusion treatment, and as described above, it has an effect of increasing the tensile strength of the present invention due to the synergistic effect of the plating layer. . That is, the presence of a nickel layer that improves the adhesion of the diffusion coating layer when manufacturing the brass electrode wire improves the tensile strength to improve the processing speed by the electrode wire more rapidly, and improves the stress resistance of the coating layer to improve the straightness of the electrode wire as a whole. Shows.

The formation of the nickel layer and the zinc layer is not particularly limited, and may be, for example, hot-dip plating or electroplating. On the other hand, although the nickel layer and the zinc layer are not shown in the drawing when forming, a washing, drying or coiling process such as degreasing, washing, pickling or ultrasonic waves may be carried out as in the prior art.

On the other hand, it is important to control the weight ratio, thickness, and diffusion heat treatment process from the viewpoint of realizing the above-described effect according to the binary-based composite coating layer of the nickel layer and the zinc layer. Specifically, it is preferable that the weight ratio of nickel to zinc is controlled from 2: 8 to 3: 7. In addition, based on before the reduction of the coating layer, the thickness of the nickel layer in the coating layer is preferably 2 to 4 μm, and the thickness of the zinc layer is preferably controlled to 6 to 12 μm. In addition, the heat treatment is controlled according to the composition of the weight ratio of nickel to zinc and is preferably performed for 6 hours or more at a temperature of 420 to 450 ° C in a vacuum furnace.

Optionally, it may further include a step of annealing after the electrode line is reduced. By this tempering treatment, after the heat treatment for releasing the surface hardening of the wire after the reduction by drawing, the tempering treatment for quenching is performed, and the structure of the nickel-zinc alloy layer is stabilized, so that powder generation during discharge processing can be reduced. Can get

Hereinafter, the present invention will be described in more detail based on preferred examples and experimental examples of the present invention. However, the technical spirit of the present invention is not limited to or limited thereto, and may be variously implemented by a person skilled in the art.

[The tensile strength]

[Processing speed]

[Automatic wiring rate]

[Processing Density]

1: electrode wire
10: core wire 20: coating layer
22: nickel layer
24: zinc layer

Claims (11)

An electrode wire for electric discharge machining in which a coating layer is formed on the surface of the core wire, wherein the coating layer is an alloy layer of nickel and zinc.
The electrode wire for electric discharge machining according to claim 1, wherein the core wire is brass.
The electrode wire for electrical discharge machining according to claim 1, wherein the weight ratio of nickel to zinc is 2: 8 to 3: 7.
A method of manufacturing an electrode wire for electrical discharge processing that is produced by reducing the thickness after forming a coating layer on a surface of a core wire, the forming of the coating layer comprising: forming a nickel layer on the surface of the core wire; Forming a zinc layer on the nickel surface; And forming an alloy layer of nickel and zinc through diffusion heat treatment.
5. The method of claim 4, wherein the forming of the nickel layer is a plating method.
The method of claim 4, wherein the forming of the zinc layer is a plating method.
The method of claim 4, wherein the heat treatment is performed at a temperature of 420 to 450 ° C for 6 hours or more.
5. The method of claim 4, wherein the nickel layer and the zinc layer are formed in a weight ratio of 2: 8 to 3: 7.
The method of claim 4, wherein the nickel layer has a thickness of 2 to 4 μm.
The method of claim 4, wherein the zinc layer has a thickness of 6 to 12 μm.
The method of claim 4, further comprising the step of tempering after reduction.

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