JPS59110516A - Electrode wire for wire-cut electric discharge machining and its manufacturing method - Google Patents

Abstract

PURPOSE:To enhance the machining efficiency by employing copper alloy, steel or ferric alloy as core material, by using a composite wire whose external layer is coated with Zn, Cd, etc., and thereby providing straightness as well as eliminating residual warp after being unwound. CONSTITUTION:A Zn pipe of 10 and 8mm.phi in outer and inner diameters, respectively, is fitted on a wire 2 of 7mm.phi, for example, made of brass (Cu-30%Zn), and a stretching process is applied. If it shall be processed into an outside diameter of 0.2mm.phi (here, thickness of the sheath 3 before supply of current is 20mum on one side), a one in straight state is heated by supply of current in the final stage of machining so as to form a 2mum thick (2% of radius) intermetal compound layer 5 consisting of Cu and Zn between the brass and Zn layer. Thus an electrode wire with excellent straightness and without residual warp after being unwound is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a composite wire suitable as an electrode wire for wire-cut electric discharge machining and a method for manufacturing the same.

(b) Background of the technology The wire-cut electrical discharge machining method involves creating an electrical discharge between the workpiece and a linear machining electrode (hereinafter referred to as an electrode wire), and then connecting the electrode wire and the workpiece. This method cuts a workpiece into a desired shape by relatively moving it, and is a conventional method.

In this wire-cut electrical discharge machining method, a long wire with a diameter of usually 0.05 to 0.25 mm is prepared as a linear electrode wire, and new wires are sequentially supplied to the electrical discharge machining part. There is.

In the electric discharge machining method, the quality of the electrode wire used has a direct and significant effect on the machining speed, machining accuracy, and surface quality of the workpiece surface, so there is a strong demand for the use of suitable materials. ing.

Generally, the requirements for this electrode wire are (1)
Machining speed: Generally speaking, the machining speed of wire-cut electric discharge machining is not necessarily high, so it is possible to increase the machining speed even a little.

(2) Good dimensional accuracy and surface texture of the workpiece,
It can also be processed without causing surface roughness.

(3) Workability: If the electrode wire breaks during cutting work, workability will be significantly impaired, so the occurrence of breaks and wires during this work should be minimal. Furthermore, when setting the wire in a processing machine, and especially when using an automatic wire feeding device, it is strongly desired that the wire be straight and free of curls.

(4) Price: As mentioned above, the electrode wire is a consumable item, so it should be inexpensive.

etc. are listed.

To further explain the above requirements for the electrode wire, the machining speed can be increased if a sufficiently stable electrical discharge is generated between the electrode wire and the workpiece, but conventionally the machining speed cannot be increased. Electrode wires that can be
This often caused roughness on the surface of the workpiece.

In addition, in order to obtain the dimensional accuracy of the workpiece, it is necessary to maintain the dimensional accuracy of the diameter of the electrode wire and to apply sufficient tension to the electrode wire. It requires something difficult to do.

・Next, regarding surface properties such as surface roughness, it is necessary to generate a uniform and stable electric discharge, and it has been difficult to satisfy both machining speed, dimensional accuracy, and machined surface condition, so we especially focused on these points. It is desired that an electrode wire that achieves both of these needs be developed.

In addition, wire breaks during cutting are caused by short circuits between the electrode wire and the workpiece, uneven discharge, and applied tension.
From this point of view, the electrode wire itself is required to have dimensional accuracy, stable discharge performance, and high tensile strength.

Furthermore, it is necessary that the raw materials are inexpensive so as not to be expensive, and that the wire drawability into fine wires of about 0.05 to 0.25 mmφ is good as electrodes for electrical discharge machining.

Conventionally, copper wire, brass wire (Cu-30%Zn), tungsten wire, etc. have been used as electrode wires for wire-cut electrical discharge machining, but these wires meet the following two sets of requirements. It wasn't necessarily fulfilled.

That is, copper wire has drawbacks such as not having very high strength, being easily broken, and being generally inferior to brass wire in terms of processing speed.

In addition, although brass wire is improved in processing speed over copper wire, it is still not sufficient, and the dimensional accuracy and surface condition of the workpiece are not necessarily good, and in addition, it is not always sufficient in terms of workability. It has some disadvantages that cannot be described clearly.

Further, tungsten wire is difficult to draw, and although the material is expensive, composite wires such as copper wire coated with lint (hereinafter simply referred to as zinc) are being considered to improve electrical discharge machinability. The electrical discharge of copper wire coated with zinc is extremely stable.
Copper wire has the excellent feature of increasing processing speed without roughening the surface of the workpiece, but as mentioned above, copper wire has low tensile strength, and zinc-coated composite wire A material with higher tensile strength is required for the core material. On the other hand, with zinc-coated composite wires, if the zinc layer scatters or evaporates and the underlying core material is exposed, the discharge becomes unstable, so the zinc layer needs to be thicker and tends to warp easily when tension is applied. Furthermore, since the strength ratio of the outer layer and the inner layer was significantly different, it was difficult to obtain the linearity of the composite wire and to fully utilize functions such as an automatic wire feeding device.

(Disclosure of the Invention) The present invention has been made to solve the above problems, and as shown in FIG. 2, the core material 2 is made of copper alloy, steel or iron alloy, and the outer layer 3 is made of Zn, Cd Alternatively, it is a composite wire made of an alloy mainly composed of these, but is characterized in that an intermetallic compound layer 5 is formed between the core material 2 and the outer layer 3.

The thickness of this metal compound layer 5 is 0.0 of the radius on one side.
Better results are obtained when it is between 5% and 5%. 00
If it is less than 5%, straightness is obtained and it is short, and if it is more than 5%, the composite wire 4 becomes brittle and tends to become curly when wound on a reel or become curly after passing through a roll.

There are various types of intermetallic compounds depending on the combination of august and outer layer particles. If the core 44 is brass and the outer layer is Zn, use ZnC.
If the material is ≦fence and the outer layer is Zn, it becomes ZnFe.

The above composite electrode wire for wire cutting of the present invention can be manufactured by the following method.

By making a composite wire coated with Zn, Cd, or an alloy mainly composed of these in the outer layer and having a wire diameter larger than the desired size as shown in Fig. 1, drawing this wire and then heating it in a straight state. -) to form an intermetallic compound layer 5 between the outer layer and the core 44. Forming this compound layer before wire drawing has an adverse effect on wire drawability. As this heating method, electrical heating is desirable. Furthermore, when the outer coating layer is made of a material with a low melting point, consideration should be given to heating the outer layer surface while cooling it so that the outer layer does not melt. The tensile strength may decrease depending on the heating described above, so when using the electrode wire for wire cutting, conditions such as temperature and time should be set so that the apparent tensile strength of the line of contact after heating is 80% or more of that before heating. It is desirable to set

The composite wire of the present invention manufactured by the above method has approximately the same electric discharge machining characteristics as the conventional composite wire as shown in Fig. 1, but there is no curling of the reel, and the wire has good straightness especially during automatic feeding and wire connection. Automatic operation can be carried out smoothly, and the production efficiency of electrical discharge machining has been significantly improved.

Next, an example will be explained.

Example 1 Brass (Cu-30%Zn) wire of 7111 mφ with an outer diameter of 1
When fitting Zn pipes with a diameter of 0 mmφ and an inner diameter of 8 mmφ and wire-drawing them to an outer diameter of 0.2 mmφ (at this time, the thickness of the Zn coating layer before energization was 20 μm on one side), the final processing step An intermetallic compound layer made of Cu and Zn with a thickness of 2 μm (2% of the radius) was formed between the brass and the Zn layer by heating it in a straight line with electricity.

When this composite wire was used in a wire-cut electrical discharge machine,
It has excellent electrical discharge machining characteristics, excellent linearity, and automatic wire connection work was performed smoothly.

For comparison, we investigated the linearity of the intermetallic compound by changing the above electrical heating conditions and changing the thickness of the intermetallic compound.

The results are shown in Table 1.

Table 1 Example 2 A 0.22 mmφ steel wire (0.3% C) was coated with Zn by electroplating to have an outer diameter of 0.25 mmφ, and then passed through a tunnel furnace and heated to a thickness of 1 .5 μm (radius ratio 1
．． 2%) of Zn and Fe were formed.

When this wire was used as an electrode wire for electric discharge machining, the electric discharge machinability was superior to that of conventional brass wire, the machining speed was high, and the straight line 11 was maintained even when unwound from the reel.
Machining accuracy was high and automatic wiring work was easy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional wire-cut electric discharge machining electrode wire, and FIG. 2 is a sectional view of the electrode wire of the present invention. 1: Conventional composite electrode wire, 2: Core material, 3: Outer layer, 4: Composite electrode wire of the present invention, 5: Intermetallic compound layer 1rI diagram W2 diagram

Claims (1)

[Claims] (1) Copper alloy, steel or iron alloy as the core material and the outer layer as Zn.
An electrode wire for wire-cut electric discharge machining, characterized in that an intermetallic compound layer is formed between a core material and an outer layer in a composite wire made of Cd, Cd, or an alloy mainly composed of these. (2. An electrode wire for wire-cut electrical discharge machining, characterized in that the thickness of the intermetallic compound layer is 0.05% to 5% of the radius of one side in claim (1). (3) The core material is copper alloy, steel or iron alloy, and the outer layer is Zn.
Based on the manufacturing method of a composite wire made of Cd or an alloy mainly composed of Cd and with an intermetallic compound formed between the core and the outer layer, an outer coated composite wire with a wire diameter thicker than the desired size was wire-drawn. A method for manufacturing an electrode wire for wire-cut electrical discharge machining, which is characterized by heating the wire in a straight state. (4) A method for manufacturing an electrode wire for wire cant electric discharge machining according to claim (3), characterized in that an intermetallic compound is generated by heating after wire drawing by applying current. (5) In claim (3), there is provided an electrode wire for wire-cut electrical discharge machining, characterized in that the heating method is heating with electricity while cooling the outer layer so that the low melting point metal or alloy of the outer layer does not melt. Manufacturing method. (6) A method for manufacturing a wire-cut electric discharge machining electrode wire according to claim (3), characterized in that the apparent tensile strength of the composite wire after heating is 80% or more of that before heating. .