JPS61279433A - Electrode wire for wire electric discharge machining and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve working efficiency of a composite wire providing zinc or zinc alloy coating layer on the surface of a core wire mode of copper or brass, by coating a specified thickness of chromic oxide on the surface of zinc or zinc alloy coating layer. CONSTITUTION:By forming a chromic oxide layer on the outside of a zinc plated layer is reduced a discharge gap 6 in electric discharge machining. As a result, spark discharging energy is efficiently consumed for melting and remov ing a workpiece 5. Thus, the working groove width 7 is also reduced and the working speed and accuracy are improved. Also, by the presence of 100-1,000Angstrom thick chromic oxide on the surface are prevented short-circuit between an elec trode wire and the workpiece and fusing of the electrode wire. Also, 1,000Angstrom or more thick one has difficulty to discharge and reduces working efficiency.

Description

[Detailed Description of the Invention] The present invention relates to an electrode wire for wire electrical discharge machining for machining by electric spark erosion, and a method for manufacturing the same. Wire electric discharge machining involves causing an electric discharge phenomenon between a machining electrode wire and a workpiece, and melting and removing the workpiece by the electric discharge, especially when processing workpieces with complex and precise shapes, such as Used for processing press molds, etc. In such electric discharge machining, it is required that the finished surface condition and dimensions of the workpiece be good, and that the machining speed be high.

[Conventional technology]

Conventionally, copper wire or copper wire has been used as the electrode wire for wire machining, but in recent years, as the range of use of wire electrical discharge machining has expanded, there has been a desire for a drastic improvement in machining speed and finish of 16 degrees. In response to the requests of
-5848 was made public.

This is a composite electrode wire in which the core material is copper wire or VL copper wire, and the surface thereof is coated with zinc or zinc alloy.

[Problem that the invention seeks to solve]

A problem with the conventional technology is the wideness of the discharge gap during electrical discharge machining.For example, in the case of an electrode wire in which a brass core material is coated with zinc to a thickness of 5 mm, such as the above-mentioned composite electrode wire, the zinc is not coated. Although the processing speed is improved compared to electrode wire,
It cannot be said that 5 to 10% is sufficient.In the case of the song title, that is, when electrical discharge machining is performed with an electrode wire coated with zinc, and in the latter case, that is, electrical discharge machining is performed with an electrode wire that is not coated. This is because the discharge energy is not consumed efficiently because the discharge gap is wider than when the discharge gap is used. Therefore, even if a zinc-coated electrode wire is used, the discharge gap during electrical discharge machining will not become large, and
It is necessary to take measures to prevent troubles such as short circuits with the workpiece and melting of the ift scratch lines. That is, an object of the present invention is to reduce the discharge jump between an electrode wire such as zinc-coated copper or zinc-coated brass and a workpiece, thereby efficiently consuming spark discharge energy for melting and removing the workpiece. At the same time, the presence of chromium oxide on the surface prevents short circuits between the electrode wire and the workpiece and melting of the electrode wire.

[Means for solving problems]

The present invention is an improvement of 15Jl on the electrode wire disclosed in Japanese Patent Publication No. 57-58411. In other words, the first factor is the presence of zinc or zinc alloy liquid l on the surface of the core material l made of copper or brass, as shown in its cross section! In a composite wire with 1 layer 2, chromium oxide 3 is added to the surface of the zinc or zinc alloy liquid l'11 layer.
It is characterized by being coated with a thickness of 00 to 1000 Å. The manufacturing method is characterized by galvanizing the surface of the core material, performing cold working of 805 or higher, and then attaching chromium oxide by immersion or electrolysis in a sulfuric acid aqueous solution containing chromium ions. It is something to do. In addition, the liquid composition of the Ii & acid aqueous solution containing chromium ions is chromium ion 5g/100g/ml, sulfuric acid 5g/30g/ml.
g/l.

[Effect]

In the present invention, chromium oxidation is applied to the outside of the galvanized layer to improve processing speed and processing accuracy. Furthermore, the presence of chromium oxide on the surface prevents short circuits with the workpiece and melting of the electrode wire.

If the thickness of the chromium obscuring layer is less than 100 8, the effect will be small, and if it is more than LOOOA, it will be difficult to cause electrical discharge and the efficiency of machining will be reduced.

In the manufacturing method, if the cold working rate after galvanizing is 80% or less, the tensile strength will be insufficient and the wire will easily break during wire electric discharge machining. If the amount of chromium ions in the aqueous solution used for chromium treatment is less than 5 g/l, chromium oxide will not adhere sufficiently, and if it is more than 100 g/i, the solution will become unstable and stable adhesion will not be obtained. Sulfur oxidation is not effective if it is less than 5g/liter (and if it is more than 30g/liter, the dissolution of the zinc layer will become greater.

〔Example〕

The present invention will be explained in more detail by way of examples.

Example 1 A 1.0-■φ moxibustion copper wire (Cu-35 steel Zn) was electroplated under the following conditions: 240 g of ZnCl2
/Q, NH4Cl2290g/Q f)) y
Zinc was coated with the liquid composition at a bath temperature of 50°C and DC30A/drr11, and the outer diameter was set to 1.1 m-φ.
Cold wire drawing was carried out to layer -φ. Using this line as a sample, sodium dichromate consisting of 111 compounds as shown in Table i1 (Nos. 1-10 are according to the present invention, Nos. 11-14 are comparative examples and not according to the present invention) under room temperature conditions. and! The degree of adhesion of chromium oxide was examined by oral inspection through the acid solution. The results are also listed in Table 1.

Table 1 Note) Sodium chromate precipitates and the solution becomes unstable, which becomes a dissolution hole in the Yanami lead layer and the wire diameter decreases at the end of 5. Samples Nos. 1 to 10, in which chromium oxide was deposited using an uninvented production method, showed good adhesion, but samples Nos. 11 to 11, in which the content of chromium ions and sulfuric acid did not meet the present invention, had poor adhesion results.

Example 2 Next, the same sample as in Example 1 was passed through the mixed liquid under the conditions according to the present invention shown in Table 1 No. 3 at various speeds, and the surface of the sample was coated with IQOA, 800 A, 1000 A according to the present invention.
Various thicknesses of chromium oxide were dip deposited. In addition, as comparative examples, we also made products with thicknesses of 50A and +500A. The thickness of the chromium oxide was measured by Auger electron spectroscopy.

For the above samples, wire cut electric discharge machine (DWC)
! Vp and [p in the table are shown in FIG.

Table 2 Note) Voltage switching: Figure 2 shows the knob machining settings for selecting the magnitude of the inter-electrode voltage (Vp) at no load, and the knob results for selecting the magnitude of the B4 current (Ip). According to FIG. 2, the machining speed was high when the thickness of the chromium oxide was 100A, 800A, and 1000A, but the processing speed was low when the thickness was 50A, and when the thickness was 150A, the processing speed was high. Things.

It seems that the discharge becomes unstable and the machining speed decreases.

Example 3 Next, as a conventional electrode wire, a thickness of chromium oxide according to the present invention of M2 and a lead coated copper wire of M2 was used.
Data on machining speed was taken for three samples A under the same conditions as in Example 2 while changing the servo voltage (uniform machining voltage V). The results are shown in Fig. 3. According to Fig. tS3, the electrode wire according to the present invention has excellent electrical discharge machinability, and its machining speed is 20-25% faster than the conventional brass wire. It was 15-20% faster than the previous version.

Example 4 Using the electrode wire according to the present invention of Example 3 and the lead-coated Li2 brass wire, the following processing test was conducted under the conditions shown in Table 2. That is, as shown in FIG.
D-11)5 d0.2R(7) ] −+ −hn
When the size of the corner H formed on the object was examined using a light microscope, it was 0.21R for the electrode wire of the present invention, but the size of the corner H formed by the electrode wire of the present invention was 0.21R. The one using a pressed copper wire was slightly larger at 0.22R.

In addition, in order to elucidate why the machining speed of the zinc-coated brass wire with chromium oxide attached to the surface of the present invention increases, the electrode wire was gradually attached to the workpiece (SK[l-11). We conducted an experiment to find out where the discharge begins when the object is brought close to the object. The test was carried out under the conditions shown in Table 2, which showed that the distance between the workpiece and the electrode wire for the zinc-coated brass wire before chromium oxide was attached to the surface was 55. The discharge started at 1, but the zinc wave f! had chromium oxide deposited on its surface to a thickness of 800A. The brass wire did not start discharging until it got close to 30 tiles. From this, it is thought that the zinc-coated brass wire of the present invention with chromium oxide attached to its surface is subjected to electrical discharge machining with a smaller discharge gap than the zinc-coated brass wire, and as a result, it is exposed to spark discharge energy. It is thought that it can be efficiently consumed for melting and removing the workpiece.

[Effects of the Invention] By using the electrode wire of the present invention, by reducing the discharge gap, spark discharge energy can be efficiently consumed for melting and removing the workpiece, improving the discharge machining speed and finishing accuracy. Therefore, the machining efficiency of the electrical discharge machine can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an electrode wire according to the present invention. Figure 2 shows the effectiveness of the electrode wire according to the present invention, Figure 3 compares the processing results of the electrode wire according to the present invention and other electrode wires, and Figure 4 shows the effectiveness of the electrode wire according to the present invention. FIG. 5 is a cross-sectional view of the workpiece and the electrode wire during electrical discharge machining, and FIG. 5 is a cross-sectional view of the workpiece when the corner is rounded. FIG. 6 is an explanatory diagram showing vprp in Table 2. Figure 1 Figure 2 Figure 2 Sword - t'taV

Claims (4)

[Claims] (1) An electrode wire for wire electrical discharge machining, characterized in that the surface of the zinc or zinc alloy coating layer is coated with chromium oxide in a composite wire in which a zinc or zinc alloy coating layer is provided on the surface of the core material. (2) The electrode wire for wire electrical discharge machining according to claim 1, wherein the thickness of the chromium oxide is 100 to 1000 Å. (3) In manufacturing the above electrode wire for wire electrical discharge machining, the surface of the core material is galvanized, then cold worked by 80% or more, and then immersed or A method for manufacturing an electrode wire for wire electrical discharge machining, which is characterized by attaching chromium oxide to a galvanized surface by electrolysis. (4) The liquid composition of the sulfuric acid aqueous solution containing chromium ions is 5 g/l to 100 g/l of chromium ions and 5 g/l to 3 g/l of sulfuric acid.
4. The method for manufacturing an electrode wire for wire electrical discharge machining according to claim 3, characterized in that the content of the electrode wire is 0 g/l.