JPH09237521A - Electrode wire for discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the inferior workability caused by Zn, reduce the occurrence of breakage or scars at the time of drawing, and improve workability and the machining speed by using a brass alloy of a Cu-Zn-B composition containing a proper quantity of boron. SOLUTION: B of 0.03-0.3wt.% is added to a Cu-Zn alloy having the Zn concentration of 40-50wt.%. This Cu-Zn-B alloy is charcoal cover-dissolved by a high-frequency heating vertical casting machine, and a wire is continuously manufactured. The wire is drawn by a die at the draft of 15%, then it is heated for 30min at 800 deg.C in the Ar atmosphere. This machining is repeated to manufacture a drawn wire having the prescribed outer diameter. When the added concentration of B is 0.03wt.% or below, breakage occurs at the time of drawing. When it exceeds 0.3wt.%, voids are easily generated in the wire at the time of drawing. When B is added and contained, crystal refinement is progressed, the drawing property in the post-process is improved, and the machining speed can be improved when the Zn concentration exceeds 40wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining electrode wire used for wire electric discharge machining.

[0002]

2. Description of the Related Art In wire electric discharge machining, a thin metal wire (electrode wire for electric discharge machining), which becomes an electrode wire, is wound up and three-dimensionally fed to the work piece, and the metal wire is used as an electrode for the work piece. Since the workpiece is melted and fused to perform the sawtooth-type machining, the three-dimensional product can be produced with high accuracy without using the electrode of the specific shape. In particular, since it is possible to process hard-to-process cemented carbide and the like with high precision, its practical range has been expanding in recent years, and for example, it is also used to process dies that are difficult to mechanically cut or cut. There is.

An example of an electric discharge machining electrode wire that has been conventionally used is a Cu-35 wt% Zn brass electrode wire. It is generally considered that the higher the Zn concentration, the higher the processing speed. However, the amount of Zn (zinc) is 40 wt%
If it exceeds, the β phase is formed, so that wire drawing cannot be performed in cold rolling. Details of this are described in, for example, "Bronze Copper Technology Research Group" 26 (1987) 181 (Nao Orimoge and 3 others).

As a high strength brass casting, Cu-40w
t% Zn brass with Al (aluminum), Fe (iron), M
n (manganese), Sn (tin), Ni (nickel), etc. are added to increase solid-liquid strengthening of the α phase and β phase and the amount of β phase produced,
Brass having improved hardness and strength has also been proposed (described in "Basics and Industrial Technology of Copper and Copper Alloys" edited by Japan Copper and Brass Association, October 1994, p. 625).

Further, in order to improve the processing speed of the Cu-35 wt% Zn brass wire, Cu-35 wt% Zn brass has a C content.
r (chromium), Mg (magnesium), Zr (zirconium), Ti (titanium), Si (silicon), Mn, A
The addition of elements such as 1 has been studied.

[0006]

However, according to the conventional electric discharge machining electrode wire, in order to improve the machining speed, Zn is used.
Although it is desired to make the concentration exceed 40 wt%, the upper limit is actually 35 wt% due to the problem of workability, and the processing speed cannot be improved without mixing other elements.

Therefore, the present invention provides a Zn content exceeding 40 wt%.
It is an object of the present invention to provide an electrode wire for electric discharge machining which can improve the workability of a brass wire while keeping the concentration.

[0008]

[Means for Solving the Problems] Zn from 40 wt% to 50 wt% and 0.03 to 0.3 wt
% B and the balance Cu.
According to this configuration, the added B (boron) refines the alloy crystal, contributes to the improvement of the wire drawability, and improves the workability. Since Zn can be made to have a high concentration exceeding 40 wt%, poor workability due to Zn can be improved. Therefore, even if wire drawing is performed, the occurrence of wire breakage and scratches can be reduced, and both workability and processing speed can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The present inventors have set the Zn concentration to 40
An attempt was made to add B (boron) to the Cu—Zn brass wire in order to maintain the workability while increasing the concentration to exceed wt%.
As a result, it was found that the crystal size of the cast material decreased as the B addition concentration increased. this is,
It is considered that the addition of B promoted the refinement of crystals and improved the wire drawability in the subsequent step.

[0010]

EXAMPLE Next, an example of manufacturing a Cu—Zn—B electrode wire according to the present invention will be described. The present inventors manufactured a Cu—Zn alloy having a conventional structure and a Cu—Zn—B alloy according to the present invention according to the composition shown in Table 1. As a comparative example, a Cu-Zn-B alloy, but a comparative alloy in which B was extremely small (0.02 wt% in this case) was also manufactured.

[0011]

[Table 1]

First, using a vertical casting machine having a heating source by high frequency heating, Cu-Zn-B alloy having the composition shown in Table 1 was melted by coating with charcoal to continuously produce a wire having an outer diameter of 1 mm. Next, the produced wire rod was subjected to die wire drawing at a workability of 15%, heated at 800 ° C. for 30 minutes in an Ar atmosphere, and then drawn at a workability of 15%. Thereafter, similarly, heating at 800 ° C. and processing of 15% or less were repeated to manufacture a Cu—Zn—B alloy electrode wire having an outer diameter of 0.2 mm. An alloy having a conventional structure and a comparative alloy were similarly manufactured.

As a result, as shown in Table 1, both the conventional alloy containing no B and the comparative alloy containing a small amount of B were broken by one-pass drawing. On the other hand, in the Cu-Zn-B based alloy according to the present invention, B is 0.03 wt%.
In the range of 0.1 wt%, wire breaking did not occur even if wire drawing was performed. In addition, in Table 1, the mark Δ is 1
It shows that wire drawing beyond the pass was possible, but there were many scratches on the surface of the wire. In addition, a circle indicates that wire drawing is possible up to an outer diameter of 0.2 mm, and a cross indicates that a wire breakage has occurred. In addition, Zn is 5 from the point of exceeding 40 wt%.
There was no problem in workability even with 0 wt%.

As is clear from the above results, the B concentration is preferably 0.03 wt% or more, and 0.02 wt% or less is not preferable because disconnection occurs during wire drawing. Also, B
When it exceeds 0.3 wt%, voids are likely to be formed inside the wire during wire drawing. Therefore, the addition range of B is 0.03 to
The optimum value is 0.3 wt%. On the other hand, JP-A-4-573
No. 5 discloses 30-40 wt% Zn-0.05-2 wt.
The electrode wire of the composition of% B-Cu alloy is shown. This electrode wire is intended to reduce the electrode adhesion to the work piece and to improve the processing speed by including B, but is intended for 30 to 40 wt% capable of processing Zn. The technical meaning of including B differs from the invention.

[0015]

As is apparent from the above, according to the present invention, Z from 40 wt% to 50 wt% is exceeded.
Cu-40 to 50 wt% Zn brass containing n.
By adding 03 to 0.3 wt% B, it is possible to reduce the occurrence of wire breakage and scratches even if wire drawing is performed, and it is possible to improve workability (drawability) and processing speed.

Front page continuation (72) Inventor Masato Watanabe 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Hitachi Power Systems Co., Ltd. Power Systems Laboratory (72) Inventor Takashi Nemoto 5-1-1 Hidaka-cho, Ibaraki Prefecture No. 1 Power Systems Laboratory, Hitachi Cable, Ltd.

Claims (1)

[Claims] 1. From 50 wt% to over 40 wt%
To Zn, 0.03 to 0.3 wt% B, and Cu as the balance.