JPS5941462A - Preparation of composite electrode wire for discharge machining - Google Patents

Abstract

PURPOSE:To obtain an extremely fine composite electrode wire used in discharge machining in good efficiency, by drawing an alloy matrix material prepared by forming a diffusion layer to the interface between the copper alloy of a core material and the coating zinc layer thereon into a wire in a high machining degree to prevent wire breakage. CONSTITUTION:A diffusion layer of zinc and copper with a thickness of 0.3mum is formed to the interface between a core material comprising a copper alloy such as brass or the like and a coated zinc or a zinc alloy layer. This zinc coated copper alloy matrix wire is drawn into a wire in a high machining degree of 90% or more to obtain a fine composite electrode wire with a diameter of 0.3mm. or less used in discharge machining. By this method, the danger of wire breakage is reduced and wire drawing workability and wire drawing yield are enhanced as well as production cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite electrode wire for electrical discharge machining, and particularly to a method for manufacturing a wire-cut composite electrode wire for electrical discharge machining, in which a brass wire is coated with zinc or a zinc alloy.

In recent years, the use of wire-cut electric discharge machining for mold machining has rapidly increased as the shape of press molds has become more complex, finer, and dimensional precision has increased. Along with this, there is an increasing desire to improve electrical discharge machining performance and productivity of electrical discharge machining.

By the way, the items required for wire cut electric discharge machining are (
1) The finished surface condition and dimensional accuracy of the workpiece are good;
(11) The speed of electrical discharge machining is high, but these are greatly influenced not only by the characteristics of the electrical discharge machine but also by the electrode wire itself. In other words, the required characteristics for electrode wires are (1) ultra-thinness to improve dimensional accuracy; (11)
Good discharge characteristics, (high strength that can withstand tension to prevent vibration in 1, θV) good conductivity, (V) straightness, (vf
Although there are costs such as
), (iiD are contradictory requirements.

Conventionally, Cu-based electrode wires and tungsten wires have been widely used, but both satisfy only part of the above-mentioned required characteristics. Therefore, recently, composite wires having the above-mentioned characteristics are being developed, for example, equity line No. 57-5648, Japanese Patent Application Laid-Open No. 56-1265.
28 and Japanese Patent Laid-Open No. 50-102999. All of these have a structure in which a material with good discharge characteristics is used on the surface to give strength to the core wire.

Of these, those with steel alloy cores have high conductivity, high strength, good workability, and are highly economical, so they are very practical. Unlike CD, alloys do not cause pollution or hygiene problems, and combined with their low evaporation temperature, they have good discharge characteristics, making them suitable as coating materials. For these reasons, a composite electrode wire having a core made of copper alloy and coated with Zn on its surface is extremely useful in industry.

Various methods can be considered to manufacture this type of composite wire, that is, to coat the core wire with a Zn layer, such as plating, extrusion, drawing, rolling, etc. However, when the coating thickness is thick, The latter three methods are preferable in terms of production speed and cost.

In other words, in the case of the extrusion method, a heated Zn billet loaded in a container of an extrusion device is pressurized by a stem,
A composite busbar is obtained by flowing and coating Zn around a copper alloy core wire placed in advance in a Goo box, and then extruding it.
A composite bus bar is obtained by inserting a copper alloy core wire into a tube and drawing it into a tight fit.The rolling method uses a slotted roll to compress Zn powder around the copper alloy core wire. This is to obtain a composite bus bar. In this way, the composite busbar (e.g. 8 to 5 cylinders) is usually thinned by wire drawing (e.g. 0, 25 to o, 207 rrrno), but if the degree of processing exceeds 90, any method Even with busbars manufactured using this method, wire breakage occurs frequently, and wire drawing workability is significantly reduced.

The causes of frequent disconnections are thought to be embrittlement of the core wire due to severe processing and insufficient adhesion between the Zn coating layer and the core wire. As a countermeasure against embrittlement caused by strong working, improving ductility through heat treatment is considered, but since this type of electrode wire generally requires high strength, heat treatment during wire drawing is practically impractical as it would result in a decrease in strength. 'c Yes - The adhesion on one side of the core can be improved to a certain extent by selecting the pre-treatment of the copper alloy wire △ and coating processing conditions (tool shape, dimensions, etc.) at the bus bar manufacturing stage, but the height 95
It is extremely difficult to achieve the 99 or higher processing required to obtain the target product size and performance number. At first glance, it seems that Zn easily adheres to brass by pressure welding during extrusion, drawing, and rolling from a metal perspective, but as this example shows, 1111-1 is suitable for high-workability wire drawing. It turns out that it is more difficult than expected to obtain a bond as strong as possible.

An object of the present invention is to provide a method for efficiently manufacturing a composite electrode wire by preventing wire breakage when manufacturing the composite electrode wire using a busbar method.

The gist of the present invention is to provide a zinc-coated steel alloy bus bar with a zinc-coated steel alloy busbar having a zinc-coated steel alloy busbar with a thickness of 90 or more, which is formed by forming a zinc and copper diffusion layer with a thickness of 0.6μ or more at the interface between the coating zinc or zinc alloy layer and the copper alloy core material. The purpose is to draw the wire with a high degree of processing and make it into an ultra-fine wire with a diameter of 0.6 mm or less.

The method of forming a diffusion layer on the bus bar is to apply hot-dip plating or electroplating on the surface of the copper alloy core wire to be used in advance, then heat treat it, extrude it, pull it out,
There is a method of coating the Zn layer thickly by rolling or the like.

Another method is to adjust the molding pressure and heating conditions when directly coating a thick Zn layer to cause mutual diffusion with the core material.

Further, there is a method in which a copper alloy core wire is coated with a Zn layer and then drawn at a processing degree of 90 or less and then diffusion heated.

When the layer diffusion thickness is 0.3μ or less, the workability that can be drawn without wire breakage, that is, the limit workability for wiredrawing, is at most 90.

The term "diffusion layer" includes not only a mutual solid solution state of (, u, and Zn) but also a case where a specific alloy composition is formed.

With a wire diameter of 0.3m96 or more, precision machining during electrical discharge machining is difficult, and it is difficult to ensure the dimensional accuracy and surface quality of the workpiece.

Hereinafter, the present invention will be explained according to embodiments shown in the drawings.

Example 1 65/35 brass wire (65% Cu-35% Zn
) is coated with Zn to a thickness of 0.8 cm at 600°C, and then diffused and heated to form a layer of Zn at the interface between the coated Zn layer 1 and the brass core 2, as shown in Figure 1. When the Zn-coated brass wires on which the diffusion layer 3 was formed were drawn, the results shown in FIG. 2 were obtained. In other words, substantially no diffusion layer was observed when the coating was extruded, and the wire drawing limit in this case was approximately 1.9 ++ Il + I y, and the working degree was 92, but as shown in Figure 2, the formation of the diffusion layer was difficult. As the wire drawing limit increases, it increases dramatically especially around 0.3μ,
It can be seen that ultra-fine wire drawing of 0.20 mm or less is possible.

Example 2 A Zn-coated brass wire with an outer diameter of 6.6 mm (
Zn (thickness: 0.8 tax) was diffusion heated in the same manner as in Example 1 to form a diffusion layer of each lamination thickness at the interface between the Zn layer and the brass, and wire drawing was performed. As a result, wire drawing before diffusion heating was performed. The limit was 90%, but as the diffusion layer was formed, the wire drawing limit increased, and also increased dramatically around 0.6μ, and then 0.2μ.
0111m, it was possible to draw an ultra-fine wire of 0.0111m or less.

Example 6 65755 brass wire with an outer diameter of 5 mm that has been pre-plated with hot-dip Zn (during the hot-dip plating, 0.0 mm was added between the Zn of the plating layer and the core material).
When the Zrr layer was coated on the surface with a thickness of 0.8 μm in the same manner as in Example 1 and the wire was drawn after extrusion, it was possible to draw the wire at 0.09 m0f. The limit reached 9998%.On the other hand, for comparison, experiments were also carried out using brass wire without molten Zn plating, but Example 1
As with the case without diffusion heating, wire drawing could only be done up to 1.9 fiO.

The wire drawing limit at this time remained at a low level of 92 points.

In addition to Zn, examples of the plating and coating layer include Zn alloy, and additive elements include, for example, Ll, N,
h, alkali metals such as Ni, Cu, Sr, Rh%Be%
There are alkaline earth metals such as Mg, which have a favorable effect on electrical discharge machinability, and AL, T1, Cu, Ni,
Sn, Si, and the like are suitable because they have the effect of improving the wire drawability of Zn without impairing the electrical discharge machinability.

As a copper alloy for the core wire, for example, 7091? u-6
Brass such as 0% Zn, 65% Cu-65% In, and No. 6. A fourth element (e.g. Ni, Co, Bes Z
r%Cr%Sns A/, Ag rare earth elements) or Cu-Ni, Cu-8n, Cu-Ti,
Cu-CrlCu-E e.

Cu-A1. ni'u-Co, Cu-Afn%Cu-8μ
Examples include alloys.

As explained above, according to the present invention, it is possible to draw a wire with a high degree of workability with an area reduction ratio of 99 or more, to obtain an ultra-fine, high-strength composite electrode wire, and to significantly reduce the risk of wire breakage. Work efficiency is greatly improved, and wire drawing yield and productivity are improved. As a result, the manufacturing cost of the product line can be significantly reduced, and its industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1 shows the amount of zinc-coated copper according to an embodiment of the present invention. A cross-sectional view of the alloy generatrix, Figure 2 is △ with respect to the generatrix. It is a processing characteristic diagram. 1: Covering Zn layer, 2: Brass, 6: Diffusion layer.

Claims (1)

[Claims] 1. A zinc-coated copper alloy bus bar with a zinc-coated copper alloy busbar formed by forming a diffusion layer of zinc and copper with a thickness of 0.6 μ or more at the interface between the coated zinc or zinc alloy layer and the copper alloy core material. A method for manufacturing a composite electrode wire for electrical discharge machining, which comprises drawing the wire with a working degree of above to obtain an ultra-fine wire with a diameter of 0.3 mm or less. 2. The method of manufacturing a composite electrode wire for electric discharge machining according to claim 1, wherein the copper alloy is brass.