JPS59224218A - Wire electrode and its manufacturing method - Google Patents

Abstract

PURPOSE:To satisfactorily perform a continuous operation while eliminating any disconnection caused in a wire electrode by forming the whole peripheral layer of the surface of an electric discharge maching wire electrode into a soft one and its core part into a high strength one. CONSTITUTION:A pressing current is supplied from a power source E to a wire electrode 1 via current conductors 4, 5 when it passes through a work W while cutting it, and through guide rollers 6, 7 from a reel 2 to a reel 3. Now, if the wire 1 is hard due to its high tension, the contact resistance of the wire 1 becomes high, resulting in its disconnection due to heat generation at power conduction. In order to improve this difficulty, the whole peripheral layer 1A on a surface part of the wire 1 is made soft, while its core part 1B is made to have sufficient tension to keep the strength of the wire 1. Namely, the whole peripheral layer 1A on the surface of the wire 1 is made softer than that of the core part 1B by making use of a heat treatment. Hereby, any disconnection of the wire electrode 1 is eliminated, enabling continuous operation to be made satisfactorily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire electrode for electric discharge machining and a method for manufacturing the same.

Conventional EDM wire electrodes have been required to have contradictory properties: high strength, good electrical conductivity, and low elastic limit. For this purpose, plas, copper, copper-cobalt, plas treated with zinc, rare earth element copper alloys, mitshu metal copper alloys, etc. have been used. In addition, BDM wire electrodes are required to have high strength and high molding pressure in any work, and the upper limit is almost limitless. However, even though the wire electrode itself has good current conductivity and high tensile strength, the contact resistance with the conductive current is high, so the wire is easily broken due to heat generation (due to large processing currents).

In view of the above-mentioned current situation, in order to improve the conventional wire material, the present invention has been made to improve the conventional wire material by subjecting it to surface heat treatment, and to improve the conventional wire material by improving the material itself. It is an object of the present invention to provide a 71i SDM wire electrode that can be easily manufactured.

Next, one embodiment of the present invention will be described. Ordinary electrode wires made of copper-cobalt alloy, for example, have a diameter of 0.1 mm.
The 2 mm wire broke when a tension of 2.2 kg was applied in the machining fluid during machining. Furthermore, a cable top wire made of an alloy with a composition of 6% cobalt, 0.6% Mitsushi metal, and the balance copper, with a diameter of 0.2 myrbO, broke when the same tension was applied. These electrode wires have a high contact resistance with a current-carrying current and do not have good quadruplicity, so they are likely to break due to heat generated by the current-carrying resistance. In the case of DM processing shown in FIG. 1, the wire electrode 1 cuts and passes the workpiece W, the wire 1 passes from the reel 2 to the reel 3, the guide rolls 6 and 7 are energized, and the wire 1 is energized. When the machining current is supplied from the power source E in step 5, if the wire has high tensile strength and is hard, the contact resistance of the wire will be high and the wire will break due to heat generation. For this reason, as shown in FIG. 2, which shows a partially enlarged cross-sectional pattern of the wire 1, the present invention softens the entire circumferential layer IN on the surface and makes the core IB sufficiently thick to maintain the strength of the wire. It is designed to have high tensile strength.

As an example of the present invention, the surface is heat treated so that the surface is soft and the core has high tensile strength. 0 from the surface of the wire
．． A laser beam annealing treatment is applied to the strength necessary to soften the portion (approximately 10 times the depth from the surface for a diameter Q of 2 myn). The inner core part IB of this surface softening layer maintains its original high tensile strength.

Next, the required amount of laser is projected over the entire circumferential layer of the surface to anneal it to the required depth, and if necessary, sub-zero treatment is performed to form a stable softened partial surface layer IA, which is the contact resistance value. Table 1 shows the results of confirming a good reduction in the amount of carbon dioxide for plus, copper, copper-cobalt alloy, and rare earth cobalt-copper alloy.

In this case, wire 1 is connected to tungsten carbide conductor 4.
The measurement was conducted by applying electricity underwater between 5 and 5.

When the moving speed of the wire electrode 1 was 2 m/i, a current value of 15 amperes was applied. The measured values in the table are expressed in mΩ.

For annealing the wire, the laser intensity is 109 W/lri,
The diameter of the wire was 0.2 m, the depth of the softened outer surface layer was approximately 0.02 mm, and the diameter of the core, which retained its original high tensile strength, was therefore approximately 0.16 m.

From Table 1, it can be seen that the electrode wire of the present invention, in which the contact resistance was reduced by about 60 times compared to the bending wire that was practically subjected to laser treatment, had virtually no wire breakage.

This is because the surface annealing treatment provides good contact with the current, resulting in extremely good current conductivity, and the temperature rise due to resistance Joule heat at the contact area is reduced.

Note that the heat treatment of the surface layer of the wire electrode can be performed not only by laser heating, but also by any heat treatment means such as plasma heating, high frequency heating, and furnace heating.

As already explained, the electrode wire of the present invention is made soft by heat-treating the entire circumferential layer to the required depth on the surface, and stabilized by undergoing a shisubzero treatment, and the inner core maintains high tensile strength. This eliminates wire breaks, improves continuous work, and significantly improves machining accuracy and work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of EDM using the wire electrode of the present invention. FIG. 2 is a partially enlarged cross-sectional view of the electrode wire. 1 wire 2, 3 reel IA wire softening surface layer 1B core 4, 5 conductor 6.7 guide roller W work E power supply

Claims (1)

[Scope of Claims] 1-A wire electrode for electrical discharge machining that travels from a supply reel through a guide roll, passes through a position for machining a workpiece, and moves to the other side via the guide roll after machining the workpiece, the surface of the wire electrode A wire electrode and a method for manufacturing the same, characterized in that the entire circumferential layer is soft and the core has a high-strength structure. 2. A wire electrode and its manufacturing method, characterized in that the entire surface layer of the wire electrode is made softer than the core by heat treatment.