JPH09323222A - Manufacture of electrode wire for elector-discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enchance machining accuracy having high tensile strength. SOLUTION: This manufacture is so featured that copper alloy powder containing a small quantity of aluminum and being partially oxidized is subjected to heat treatment in an inert atmosphere, whereby reduced copper powder containing alumina is obtained and, after such copper powder is thermally pressurized and formed into a compact, it is sealed in the sheath of a copper alloy containing zinc under the vacuum, and then this compact is made into hot extrusion molding, thereby securing a reinfroced copper core dispersively containing minute aluminum oxide and a conductive wire having a brass surface layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrode wire for electric discharge machining,
In particular, the present invention relates to a method for producing an electrode wire having electric discharge characteristics and mechanical strength suitable for wire cut electric discharge machining.

[0002]

2. Description of the Related Art There is an electric discharge machining method as a method for performing precision machining on a metal material. Among such electric discharge machining, an electric discharge machining electrode wire is used for wire cutting for manufacturing a press die or the like. In such electric discharge machining, it is necessary to maintain good precision of the cut surface, and if the electrode wire for electric discharge machining becomes loose during use, the machining accuracy also decreases. The electrode wires must always be used in tension.

Conventionally, thin wires made of brass have been used as such electrode wires for electric discharge machining. However, there is a tendency that the tensile strength tends to decrease during use, and there is a limit to improving machining accuracy, and the service life is limited. Was short. On the other hand, as an electric discharge machining electrode wire capable of improving both machining speed and machining accuracy, the core material is 0.1 to 1.0% in Cu.
A sintered alloy in which Al is dispersed as internal oxide particles, in which Zn or Al is plated on the surface of a composite wire whose skin material is Cu has been proposed (JP-A-57-20113).
No. 3).

[0004]

However, such an improved electrode wire cannot be said to have a sufficient tensile strength similarly to the conventional brass electrode wire, and a higher strength electrode wire for electric discharge machining is required. Had been. Therefore, in view of the problems in the prior art, the present invention has an object to provide a method of manufacturing an electrode wire for electric discharge machining, which has a higher tensile strength, can improve machining accuracy, and has a long service life. And

[0005]

A method for manufacturing an electrode wire for electric discharge machining according to the present invention is directed to a reduction containing aluminum oxide by heat-treating a copper alloy powder containing a small amount of aluminum and partially oxidized in an inert atmosphere. Obtained copper powder, heat-pressurized the copper powder to form a compact, then encapsulated in a copper alloy sheath containing zinc under vacuum, and hot extruded this to strengthen the copper containing dispersed fine aluminum oxide. It is characterized in that a conductive wire having a core material and a brass surface layer is obtained.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In producing an electrode wire by the method of the present invention, a copper alloy used as a raw material of a core material is obtained by mixing pure copper and a small amount of aluminum, and the content of aluminum is 0. It is preferably in the range of 0.1 to 0.7% by weight. When the aluminum content is too low, the workability is good but the improvement in strength is small,
On the other hand, if the amount is too large, the mechanical strength will be high, but the workability will be deteriorated, so neither is desirable. Such a copper alloy is made into a powder state by spraying in a molten state using water, steam, or the like, or by alloying copper powder and aluminum powder by pulverizing and mixing in a mixer such as a ball mill. Can be used.

Such a copper alloy powder oxidizes the surface by air oxidation or the like in a heated state, if necessary, then reduces the copper oxide by heat treatment in an inert atmosphere, and converts aluminum to aluminum oxide. Is converted to The aluminum oxide-containing reduced copper powder thus obtained is further subjected to a reduction treatment by heating it in a reducing atmosphere such as hydrogen, if necessary, and then pressurized by a press to form a pressed compact. Sintering.

As the sheath for enclosing the above-mentioned copper powder press-formed body, a sheath made of a copper alloy containing zinc, so-called brass is used. The brass preferably has a zinc content in the range of 10 to 40% by weight. When the zinc content is less than 10% by weight, the tensile strength is not sufficiently improved, and the zinc content is If it exceeds 40% by weight, heat resistance and wire drawing workability are deteriorated, which is not desirable. By using such a brass sheath, it is possible to obtain an electrode wire for electric discharge machining having excellent electric discharge characteristics, mechanical strength and deterioration resistance characteristics.

A press-molded body of copper powder is sealed in a sheath as described above under vacuum to form a billet. The billet thus obtained is formed into a roughly drawn wire by using an extruder, and further drawn by a wire drawing machine. By drawing the wire in order and pulling it down to a diameter of about 0.1 to 0.2 mm, a thin wire suitable for an electrode wire for electric discharge machining can be obtained.

[0010]

【Example】

(Example) Aluminum was mixed with pure copper, and
A copper alloy containing 35% by weight of aluminum was obtained, which was melted and pulverized by a jet water flow to have an average particle size of about 2
A 0 μm powdered copper alloy was obtained. Then, this powdered copper alloy is heated in the air at 300 to 350 ° C. for 10 minutes to oxidize the surface of the powder particles, and further heated at 800 ° C. for 1 hour in a nitrogen atmosphere having an oxygen partial pressure of 5 × 10 ⁻⁵ Torr or less. The aluminum was converted to alumina.

The alumina-containing copper powder thus obtained was once pulverized, heated in a hydrogen atmosphere at 500 ° C. for 1 hour to remove oxygen remaining in the copper, and then pressed to a density of 6 g / cm ^3. It was a molded body. Then, this molded body is heated at 500 ° C. in a vacuum to remove moisture, adsorbed gas and the like and is sintered, and then, in a cylinder formed of brass of 10% zinc, the weight is 8 times that of the brass cylinder. The sintered body was inserted and vacuum-sealed to obtain an extrusion molding billet.

Next, the billet was heated to 950 ° C. and hot extruded at a die temperature of 300 ° C. and an extrusion ratio of 76 to obtain a rough-drawn wire. The thus-obtained rough drawn wires were sequentially drawn by a conventional method and drawn down to a diameter of 0.2 mm, and the obtained thin wire A was measured for tensile strength (N / mm ² ) and conductivity (% IACS). . When the metal composition of the cross section of the fine wire A was examined, about 5 μm on the surface had a brass composition.

(Comparative Example) Except that the sintered body of copper powder was vacuum-sealed in a brass cylinder, it was inserted in a cylinder made of oxygen-free copper of the same shape and vacuum-sealed. To produce an extrusion molding billet. Then, similarly to the example, the mechanical strength and the conductivity of the thin wire B having a diameter of 0.2 mm obtained by drawing were measured, and the results are shown in Table 1 together with the measurement results of the example. .

For reference, the zinc content is 35% by weight.
Table 1 also shows the values of mechanical strength and conductivity measured for the thin wire C of 0.2 mm in diameter made of brass and the thin wire D of 0.2 mm in diameter manufactured from oxygen-free copper. This result shows that the fine wire A manufactured by the method of the present invention has much higher tensile strength than the brass fine wire C and the fine wire B manufactured by using the copper sheath, and the electric discharge machining is performed. It can be seen that the electrode wire for use can withstand a large tensile stress.

[0015]

[Table 1]

Further, the thin line A of the example and the thin line B of the comparative example.
When the electric discharge characteristics of the thin wire B ′ plated with zinc and the thin brass wire C in the electric discharge machining liquid were examined, it was confirmed that they all had exactly the same electric discharge characteristics. Further, when the change in the tensile strength at 650 ° C. was examined for the thin wire A of the example and the brass thin wire C of the comparative example, the strength of the brass thin wire C was reduced to 27% of the room temperature, whereas the strength of the thin wire A was 27%. It was found that the decrease in the value of the value stopped at 55%.

[0017]

EFFECTS OF THE INVENTION According to the method of manufacturing an electrode wire for electric discharge machining of the present invention, it has higher strength than the electrode wire according to the prior art, particularly excellent strength at high temperature, and less deterioration. There is an effect that a long-life electrode wire can be obtained which can be used to maintain processing accuracy.

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[Procedure amendment]

[Submission date] April 10, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In producing an electrode wire by the method of the present invention, a copper alloy used as a raw material of a core material is obtained by mixing pure copper and a small amount of aluminum, and the content of aluminum is 0. It is preferably in the range of 0.1 to 0.7% by weight. When the aluminum content is too low, the workability is good but the improvement in strength is small,
On the other hand, if the amount is too large, the mechanical strength will be high, but the workability will be deteriorated, so neither is desirable. Flour in such a copper or alloy is sprayed with water or steam in the molten state, or copper powder and blender of the aluminum powder ball mill etc.
It is possible to use a powder that has been powdered by a method such as crushing, mixing , and alloying.

Claims (2)

[Claims] 1. A reduced copper powder containing aluminum oxide is obtained by heat-treating a copper alloy powder containing a small amount of aluminum and partially oxidized in an inert atmosphere, and heat-pressurizing the copper powder to form a compact. After that, it is sealed in a sheath of a copper alloy containing zinc under vacuum, and is hot extruded to obtain a conductive wire having a reinforced copper core material containing fine aluminum oxide dispersed therein and a brass surface layer. Manufacturing method of electrode wire for electrical discharge machining. 2. The method for producing an electrode wire for electric discharge machining according to claim 1, wherein brass having a zinc content in the range of 10 to 40 wt% is used as the copper alloy containing zinc.