JP2013139073A - Electrode wire for wire electric discharge machining and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small diameter electrode wire for wire electric discharge machining usable under a high voltage or a high tension.SOLUTION: An electrode wire 10 comprises a steel wire 11 containing 0.78 to 1.05 mass% of carbon and an aluminum plating layer 12 formed on a surface of the steel wire 11. A diameter of the wire is 30 to 100 μm and a tensile strength is 2,000 to 4,000 MPa. An unevenness 12a is formed on a surface of the plating layer 12 and a surface area is increased.

Description

  The present invention relates to an electrode wire for wire electric discharge machining and a method for manufacturing the same.

As a cutting method for cutting a workpiece (workpiece) into a desired shape, a wire electric discharge machining method is known.
In the wire electrical discharge machining method, an electrical discharge machining electrode wire made of wire is passed through the workpiece, a voltage is applied between the electrode wire and the workpiece to cause an electrical discharge, and the workpiece is melted by the heat generated by the electrical discharge. In addition, it is performed by removing the melted portion by vaporization explosion of the working fluid.
The workpiece is moved back and forth, left and right, and continuously melted and removed along the trajectory of the electrode lines on the workpiece, whereby cutting into a desired shape is performed.

  By the way, since the precise processing becomes possible as the wire diameter of the electrode wire becomes smaller, there is a demand for reducing the diameter of the electrode wire. On the other hand, tension is applied so that the electrode wire does not bend during electrical discharge machining, but if the diameter is reduced, the applied tension cannot be withstood and breakage tends to occur, so the tensile strength of the electrode wire is improved. There is also a request.

Conventionally, copper wires such as copper wires and brass wires are often used as electrode wires because they are inexpensive and have high conductivity. However, copper has a relatively low tensile strength, so disconnection occurs when the diameter is reduced. Frequently occurred and could not meet the above request.
A tungsten wire or molybdenum wire with high tensile strength is sometimes used as the small-diameter electrode wire, but it is very expensive.

Therefore, as described in Patent Document 1, it is also considered that the surface of a steel wire serving as a core wire is coated with copper and zinc as an electrode wire.
Such an electrode wire has a tensile strength improved to some extent because the core wire is a steel wire as compared with a copper-based wire, and is also cheaper than a tungsten wire or the like.

JP 2000-107943 A

However, even in the case of a steel wire plated with copper on the surface, the copper forming the surface portion has a low tensile strength, so that it is still insufficient for reducing the diameter and increasing the tension.
Moreover, since copper plating itself has poor electric discharge machining performance, in order to improve electric discharge machining performance, it is necessary to coat a low melting point metal such as zinc on the outer layer as described in Patent Document 1 or to alloy this with copper. However, due to this, the conductivity of the electrode wire drops abruptly.
If the thickness of the plating is increased in order to prevent such a decrease in conductivity, the tensile strength is decreased this time, which is contrary to the demand for a smaller diameter.

From such characteristics of copper, when applying high voltage and high tension to the electrode wire of Patent Document 1 to improve the processing speed and accuracy, there is a problem that the electrode wire is disconnected.
And, when trying to reduce the diameter of the electrode wire, the tensile strength further decreases, so it was practically impossible to reduce the diameter of the electrode wire plated with copper to a certain level or less.

  Therefore, the problem to be solved by the present invention is to provide a small-diameter electrode wire that can be used under high voltage and high tension, and a method for producing the same.

  In order to solve the above-described problems, an electrode wire for wire electric discharge machining according to the present invention includes a steel wire containing 0.78 to 1.05% by weight of carbon, an aluminum plating layer formed on the surface of the steel wire, The wire diameter is 30 to 100 μm, and the tensile strength is 2000 to 4000 MPa.

The aluminum plating layer preferably has cracks that increase the surface area.
As a method of manufacturing an electrode wire for wire electric discharge machining that causes such cracking, a step of plating the surface of a steel wire to form an aluminum plating layer, a wire drawing of the steel wire, and simultaneously the aluminum plating layer And a step of generating cracks that increase the surface area.

By forming the electrode wire by plating the steel wire with aluminum, the boiling point of aluminum is lower than that of copper (aluminum is about 2750K and copper is about 2855K). .
Therefore, it is possible to realize a small-diameter electrode wire that can be used under a high voltage or high tension and can obtain a good processing speed and accuracy.

Also, since aluminum has a smaller work function (energy required to remove one electron from the surface) than copper (aluminum is about 4.2 eV, copper is about 4.65 eV), discharge is performed quickly, and processing Speed is further improved.
Furthermore, since aluminum is lighter and cheaper than copper, the weight and cost of the electrode wire can be reduced.

  When the aluminum plating layer of the electrode wire has a crack that increases the surface area, the number of discharge points increases due to the surface irregularities, and the discharge efficiency is improved, and the heat dissipation and cooling effects accompanying the increase in surface area are also improved.

Cross section of electrode wire for wire electrical discharge machining Flow chart showing the outline of the entire manufacturing process of electrode wire for wire electrical discharge machining The perspective view which shows the outline | summary of the use condition of the electrode wire for wire electric discharge machining

Hereinafter, embodiments of the present invention will be described.
As shown in FIG. 1, the wire electric discharge machining electrode wire 10 according to the embodiment includes a steel wire 11 serving as a core wire and an aluminum plating layer 12 formed on the surface of the steel wire 11.

Here, the wire diameter of the electrode wire 10 is 30 to 100 μm, and the tensile strength thereof is 2000 to 4000 MPa.
The steel wire 11 serving as the core wire contains 0.78 to 1.05% by weight of carbon. Examples of such steel wires 11 include so-called 80 carbon piano wires and so-called 100 carbon piano wires.
As shown in FIG. 1B, the aluminum plating layer 12 has a large number of irregularities 12a on the surface due to fine cracks. Therefore, the surface area is increased as compared with the case where there is no unevenness 12a.
The thickness of the aluminum plating layer 12 is not particularly limited as long as the tensile strength of the electrode wire 10 is 2000 to 4000 MPa. Also, the dimensions of the unevenness 12a such as the height difference are not particularly limited.

  The electrode wire 10 is manufactured through a process as shown in FIG. Here, the minimum number of steps is shown, and other steps may be added.

First prepared wire of wire diameter 4.0~6.0mm the (steel wire 11) with _{S 0.}
It is assumed that the scale is removed as appropriate by pickling this wire in advance.
Next, in _{S 1,} the the wire eg dry wire drawing machine, to TEMPORARY drawing the wire diameter 0.4 to 1.5 mm.
Further in S _2, it performs patenting treatment by heating and rapidly cooling the drawn and wire rod.

In S ₃ , the patented wire is subjected to a plating process to form an aluminum plating layer 12 on the surface thereof.
The plating method is not particularly limited and is a general method. Specifically, an electroplating method and a molten salt plating method can be exemplified. Further, the case where an aluminum film is formed by conform, which is a kind of extrusion processing method, is also included in the plating treatment referred to in this specification.
Incidentally, as a document disclosing the details of the aluminum plating by the electroplating method, Japanese Patent Application Laid-Open No. 2008-195990 discloses a paper disclosing details of the aluminum plating by the molten salt plating method. "Al and Al alloy electrodeposition using molten salt / room temperature ionic liquid" can be mentioned.

Finally, in S _4, by a wire which the aluminum layer 12 is formed, for example, wet-drawing machine, and wire drawing (secondary drawing) finish diameter 30 to 100 [mu] m, the electrode line is completed.
At the time of wire drawing, as shown in FIG. 1B, the tensile force, the area reduction rate, etc. are adjusted so that a large number of irregularities 12a accompanying fine cracks are intentionally generated in the aluminum plating layer 12. To do.

  The electrode wire 10 and the manufacturing method thereof according to the embodiment are as described above. Next, the usage method will be described with reference to FIG. Note that FIG. 3 is a schematic diagram and does not accurately represent the dimensions of each component.

  First, a workpiece w is placed on a table (not shown) so as to be movable in a plane, a start spot s is formed in the workpiece w, and the electrode wire 10 of the embodiment is passed therethrough. A slight gap exists between the start spot s and the electrode line 10.

One end of the electrode wire 10 is wound around the supply reel 20 and the other end is wound around the take-up reel 30 via the tension roller 40. With the rotation of the supply reel 20 and the take-up reel 30, the electrode wire 10 is sent from the supply reel 20 to the take-up reel 30.
Here, the tension applied to the electrode wire 10 is adjusted by a pair of tension rollers 40.

In this state, a voltage is intermittently applied from the power supply 50 between the electrode wire 10 and the workpiece w. In addition, the electrode wire 10 and the workpiece | work w shall be immersed in discharge liquids, such as water.
By applying the voltage, a discharge is generated between the electrode wire 10 and the workpiece w, and the heat associated therewith starts melting while the portion around the electrode wire of the workpiece w remains in a non-contact state.
When the workpiece w is moved while the electrode wires 10 are being fed forward, a cut line c is formed by melting along the trajectory of the electrode wires on the workpiece w, and cutting is performed.

Here, the electrode wire 10 of the embodiment has a relatively small wire diameter of 30 to 100 μm and nevertheless has a large tensile strength of 2000 to 4000 MPa because the core wire is the steel wire 11. Therefore, it can be used under high tension, and the processing speed and accuracy are improved.
Also, since aluminum has a relatively high conductivity (about 61% IACS), the discharge performance is also good.

Furthermore, since the unevenness 12a is formed on the surface of the electrode wire 10, the number of places where electric discharge occurs is increased, and the processing efficiency is further improved.
Since the surface area of the electrode wire 10 is increased by the unevenness 12a, the efficiency of electrode wire cooling by the latent heat of vaporization of the aluminum plating layer 12 is also improved. Therefore, it can be used at a higher voltage, and the processing speed is further improved.
Since aluminum has a small work function, the rise time from application of voltage to the start of discharge from the electrode wire 10 is fast, and the processing speed is also improved from this viewpoint.

  It should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications and variations within the scope and meaning equivalent to the terms of the claims.

For example, the aluminum plating layer 12 of the electrode wire 10 may be prevented from cracking.
Further, between the steel wire 11 and the aluminum plating layer 12, an iron-aluminum alloy that may be generated during the plating process may be included.

DESCRIPTION OF SYMBOLS 10 Wire electrical discharge machining electrode wire 11 Steel wire 12 Aluminum plating layer 12a Concavity and convexity 20 Supply reel 30 Take-up reel 40 Tension roller 50 Power supply w Workpiece (work)
s Start spot c Cut line

Claims (3)

A steel wire containing 0.78 to 1.05% by weight of carbon, and an aluminum plating layer formed on the surface of the steel wire,
The wire diameter is 30-100 μm,
An electrode wire for wire electric discharge machining having a tensile strength of 2000 to 4000 MPa.   The electrode wire for wire electric discharge machining according to claim 1, wherein the aluminum plating layer has a crack that increases a surface area. A step of plating the surface of the steel wire to form an aluminum plating layer;
A method of producing an electrode wire for wire electric discharge machining, comprising: drawing the steel wire, and simultaneously generating a crack that increases a surface area of the aluminum plating layer.

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