JPS62208827A - Electrode wire rod for wire electric discharge machining - Google Patents

Abstract

PURPOSE:To perform machining excellent in machining precision and surface roughness at a low cost by using at least one metal element wire, multiple metal element wires or twisted metal element wires coated with a functional metal at a thickness of 0.1mum or more as an electrode wire rod. CONSTITUTION:Alloy steel or high-carbon steel is used for a metal element wire; a single wire or a strand of multiple wires or a twisted wire, if necessary, is used to have an adequate cross section area according to the tensile force. For precision machining, the cross section area is made equal to the circle area of 10-300mumphi at the tensile force of 150kgf/mm<2>; for high-speed machining, the cross section area is made equal to the circle area of 30-500mumphi at the tensile force of less than 150kgf/mm<2>. In addition, it is coated with an adequate functional metal at a thickness of 0.1mum or more by chemical, physical deposition method, plating, etc., as required. Coating may be applied before or after twisting. Machining performance excellent in machining speed and machining precision at a low cost can be improved even for a thick work by using a thus processed electrode wire rod.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a high-tension, strong, and economical electrode wire for wire electrical discharge machining used in high-speed, high-intensity machining, and in particular, to The present invention relates to an electrode wire for wire electrical discharge machining that has high machining performance for large workpieces.

<Prior art and its problems> The wire electrical discharge machining method generates an electric discharge between a workpiece and an electrode wire, moves the electrode wire and the workpiece relatively, and moves the workpiece into a desired shape. It is cut into shapes. The wire electrical discharge machining method is a method that has been used for a long time, and the quality of the electrode wire used for this method depends on the machining speed, machining accuracy, and
Since it directly affects the surface properties of the workpiece, it is necessary to use materials suitable for machining.

The following characteristics are generally required for electrode wires.

(1) High machining speed (2) High dimensional accuracy of the workpiece and sufficiently smooth surface of the machined surface (3) Good workability (less wire breakage during work)
(4) Economic efficiency (as it is a consumable item, it should be as inexpensive as possible). The machining speed can be increased if the electrical discharge between the electrode wire and the workpiece is sufficiently stable. The surface roughness of the workpiece increases and roughness occurs. In order to improve the dimensional accuracy of the workpiece, it is necessary to reduce the diameter of the electrode wire and its deviation, and to apply as high a tension as possible during processing to reduce "wire wobbling".

Various electrode wire materials have been used up to now due to requirements for discharge stability and high tensile strength properties.

The wire diameter of conventionally used materials is 0.05 to 0.25.
mmφ, and materials with a relatively large wire diameter within this range are often made mainly of copper or brass to which various functionalized metals are added to improve electrical discharge machining characteristics.

Here, the functionalized metal is a metal that emits electrons sufficiently easily (that is, has a small work function).

A metal with a low boiling point that exhibits high functionality during wire electrical discharge machining.

Wire materials with small wire diameters are often made mainly of tungsten to which various functionalized metals are added in order to provide high tensile strength properties. For example, in a recent patent,
JP-A No. 59-222546 discloses 2010~40w for copper.
t% and Be added in an amount of 0.05 to 3 wt%.
t% and SiO, 1 to 5 wt%.

Conventional electrode wires do not meet the above requirements in the following respects.

First, copper-based wires do not have a high enough tensile strength and are prone to breaking.
Also, the processing speed is not high. Further, although the machining speed of Brass Ne is higher than that of Copper 4, it does not have sufficient tensile strength and does not satisfy requirements in terms of machining workability, dimensional accuracy and surface roughness of the workpiece. Brass-based wires are also more difficult to wire-draw than copper-based wires. Tungsten-based wires for thin wire electrodes are expensive, difficult to wire-draw, and have insufficient electrical discharge machinability.

Furthermore, as the thickness of the workpiece increases, the processing efficiency deteriorates. That is, as is clear from the fact that the machining speed is expressed as the machining area per unit time (machining thickness x machining length, mm27m1n), as the thickness increases, the machining length becomes smaller.

Furthermore, there is a limit to the thickness of the workpiece that can be processed. One of the major reasons for this is that the machining fluid does not flow sufficiently in the thickness direction of the workpiece.

<Objective of the Invention> The object of the present invention is to enable processing under processing conditions that have sufficiently high tensile strength and a low frequency of wire breakage, and to realize processing at a high processing speed that was previously unobtainable. Furthermore, we have developed a new, sufficiently low-cost wire discharge method that can achieve extremely high speed, high machining accuracy, and sufficiently smooth machining surfaces for thick workpieces that were previously difficult to machine by electrical discharge machining. The purpose is to provide an electrode wire for processing.

<Structure of the Invention> The first aspect of the invention provides an electrode wire for wire electrical discharge machining characterized by having a plurality of metal wires.

A second aspect of the invention provides an electrode wire for wire electrical discharge machining, characterized in that it is made of at least one metal wire to which a functionalized metal is attached to have a thickness of 0.1 μm or more. It is something.

A third aspect of the invention provides an electrode-wire material for wire electrical discharge machining, characterized in that a functionalized metal is adhered to a stranded metal wire to an adhesion thickness of 0.1 μm or more. It is.

In the case of an electrode wire for dense processing, the tensile strength of the metal wire is 150 kgf/ma+2 or more, and the electrode wire has a tensile strength of 150 kgf/ma+2 or more.
It is preferable that the cross-sectional area is equal to a circular area of 0 to 300 μmφ.

Further, in the case of an electrode wire for high-speed processing, it is preferable that the metal wire has a high tension of less than 150 kgf/mm2, and that the electrode wire has a cross-sectional area equal to a circular area of 30 to 500 μmφ.

The present invention will be explained in more detail below.

[1] In the present invention, a metal wire is used as the electrode wire base material.

Metal wires can be used as electrode wire base materials for copper, brass, tungsten, etc., or metals containing special alloying elements in these metals. (1) High processing speed (2) Dimensional grain size of the workpiece (3) Good workability (less wire breakage during work),
(4) Economic efficiency (as it is a consumable item, it should be as inexpensive as possible), etc. Any material may be used as long as it satisfies the requirements, but in the present invention, the electrode wire bus Instead of using strands containing various special alloying elements to provide high properties as a material, it is preferable to use steel wires whose tensile strength is less than 150 kgf/+m2, that is, for high-speed processing. kgf/llm2 or more, that is, for precision machining, 150 kgf/mm2
If it is less than 150 kgf/mm2, we take advantage of the characteristics that the material is cheap and have an extremely large economic effect, and if it is more than 150 kgf/mm2, we take advantage of the characteristics that the line blur is small and precision machining characteristics are good.

In other words, it can be used as a single wire or as a strand made up of multiple single wires, or as a twisted wire if necessary, so as to have an appropriate cross-sectional area according to the tensile strength of the wire, and if necessary, it can be used with various functionalized metals as described below. By attaching it by various methods and selecting appropriate treatment such as redrawing if necessary, the tensile strength can be increased to 150 kgf/1I12 even if a wire with a tensile strength of less than 150 kgf/mm+2 is used.
The electrode wire material for wire electrical discharge machining of the present invention was made by utilizing the characteristics of each of the above-mentioned wires.

In other words, as mentioned above, there are cases in which electrode wires formed by twisting high tensile strength wires used mainly for precision processing, and cases in which the wires are twisted to have a thicker wire diameter to emphasize processing speed with low tensile strength. In some cases, electrode wires that have been used are used.

Note that the strands may be used as they are, but they may be redrawn to have higher tensile strength.

(1) The tensile strength of the electrode wire material used is 150 kgf/
A wire having a diameter of mm2 or more is effective mainly in the field of use as an electrode wire for precision processing.

In order to perform precision machining, it is necessary to minimize line deviation during electrical discharge machining. For this purpose, an electrode wire with high tensile strength must be used. Since the electrode wire according to the invention is preferably made by twisting a plurality of strands together, the strands themselves must have high tensile strength properties.

An example of an economical wire with a tensile strength of 150 kgf/mm" or more is Co70.10-0.20%, Cr10.
40-0.80%, Ni/0.70-1.00%, V
lo, 03-0.08%, [; u/O, 15-0
, 50%, Mo/0.40-0.60%, B10.
There are nine steel wires containing 0.02 to 0.006%. However, as for a more economical wire, a high carbon steel wire such as C10.4 to 0.8%, which does not contain such special components, can also function satisfactorily. That is, by adjusting the carbon content, heat treatment conditions, and wire drawing conditions within this range, high tensile strength can be easily obtained.

When using strands with a tensile strength of 150 kgf/mm" or more, the cross-sectional area after twisting etc. to make the electrode wire is 10
The circular area range is from μmφ to 500 μmφ. The cross section does not necessarily have to be a perfect circle, and may have any shape.

If the cross-sectional area is less than 10 μιΦ, the machining speed will be insufficient, and if the cross-sectional area is 500 μιΦ, the machining accuracy will deteriorate.

(2) The tensile strength of the strands of the electrode wire used is l 50 kgf
If the diameter is less than /Iflo+2, the wires are twisted to have a larger diameter and used as electrode wires for high-speed processing.

In this case as well, the processing characteristics can be improved by using an electrode wire made by twisting together wires with a tensile strength of 150 kgf/mm2 or more, but it is extremely economical to use wires with a tensile strength of less than 150 kgf/mob2. big.

When using a wire with a tensile strength of less than 150 kgf/mm2, the cross-sectional area after twisting the wire to make an electrode wire is 30 kgf/mm2.
The circular area range is from μmφ to 500 μmφ. The cross section does not necessarily have to be a perfect circle, and may have any shape.

If the cross-sectional area is less than 30 μmφ, the machining speed will be insufficient, and if the cross-sectional area is SOO μmφ, the machining accuracy will deteriorate.

Compared to the case where a wire having a tensile strength of 150 kgf/mII+2 or more is used, if the cross-sectional area is made larger, large current electric discharge machining becomes possible and the machining speed increases.

The electrode wire material for wire electrical discharge machining of the present invention may be used as a composite wire made by combining a plurality of metal wires as is, but it may also be used by adhering various functionalized metals as described below.

[2] In order to perform electrical discharge machining efficiently and stably, it is also necessary to "increase electrical discharge energy." For this purpose, if various functionalized metals, which will be described later, are attached to the surface of the electrode wire by various methods, which will be described later, the processing speed will be increased, and the processing accuracy will also be improved. There are two methods for attaching the functionalized metal to the electrode surface: one method involves attaching the functionalized metal to the wire and then twisting the wire, and the other method involves twisting the functionalized metal and then attaching the functionalized metal. In either case, the processing characteristics are significantly improved compared to electrode wires that do not have functionalized metal attached.
In the former case, the characteristic improvement effect is more remarkable. The reason for this is thought to be that the functionalized metal adheres more uniformly and stably in the former case.

Functionalized metal refers to a metal that emits electrons sufficiently easily (that is, has a small work function) and has a low boiling point, which allows it to exhibit high functionality during wire electric discharge machining.

Such functionalized metals include Al1. Si,■
, [;r, Mn, Ni, Cu, Zn, Ga, G
e, Zr, Nb, In.

Single element of sb, If, Ta, Pb, Ni-
Examples include alloys of Cu, Cu-Zn, and Ni-Zn, as well as composites in which l is added to these m-forms and alloys.

As a method for attaching these functionalized metals, CV
Examples include PVD (chemical vapor deposition), vacuum deposition, sputtering, ion blating, etc., and pultrusion forging methods. 0 by any method or a combination of these methods.
．． It is adhered or coated to a thickness of 1μ1 or more.

The film thickness of the functionalized metal is set to 0.1 μm or more whether it is applied to the strands and then twisted, or when the strands are twisted and then attached. If it is less than 0.1 μm,
Its mechanical strength is insufficient, and the function of the functionalized metal is not fully demonstrated.

As described above, by attaching various functionalized metals to the surface using various methods, processing characteristics can be greatly improved.

In addition, by using the electrode wire with the above-mentioned cross-sectional area, the electrode wire of the present invention has a tensile strength that is more than twice that of conventional electrode wires, so wire runout during electrical discharge machining is small, and The quantity is also reduced, and machining accuracy is significantly improved.

Furthermore, the electrode wire of the present invention has the effect of the twisted wire k
It is highly effective in improving machining speed, machining accuracy, and machined surface roughness.

In other words, in the present invention, preferably, the electrode wire is made of a plurality of strands twisted together, so that the cross section of the electrode wire is uneven, and the machining fluid does not come into contact with the electrode wire and the processing surface of the workpiece. ie, in the thickness direction of the workpiece. Due to this effect and the electric discharge effect between the workpiece and the electrode wire, which has an uneven cross section and is fed downward at a constant speed, for example, the machining speed is dramatically improved.

Practical example The present invention will be specifically described below with reference to Examples.

Electrode wires were produced using the wires shown in Table 1 under the conditions shown in Table 1.

Figure 1 shows the results of machining D-11 plate material S as the workpiece and comparing the machining accuracy, machining speed, and machined surface roughness.
The machining characteristics were evaluated in terms of machining accuracy and machined surface roughness, as shown in Figure 6. The same figure also shows the machining characteristic values when the thickness of a workpiece made of the same material is changed.

Note that the vertical axis in FIGS. 1 and 2 evaluates the machining accuracy based on the width of the machining groove. The smaller the processing groove width and the smaller the variation range, the better the processing dimensional accuracy of the workpiece.

Example 1 and Comparative Example 1 As shown in Table 1, electrode wires of Invention Examples 1 to 4 and Comparative Example 1 were produced as follows.

(Example 1 of the present invention) Tensile strength mainly composed of FC is 255 kgf/mtrr2
An electrode wire material with a cross-sectional area equal to the area of a circle with a diameter of 50 μmφ made by twisting multiple wires together.

(Example 2 of the present invention) A wire with a tensile strength of 255 kgf/am2 was heated with 5 μmF.
Zn of
An electrode wire with a cross-sectional area equal to the area of a circle of mφ.

(Example 3 of the present invention) A plurality of wires having a tensile strength of 255 kgf/mm2 were twisted together to have a cross-sectional area equal to the area of a circle with a diameter of 40 μmφ. An electrode wire material with an average thickness of 5 μm of Zn as a functional metal adhered to the surface by electroplating.

(Example 4 of the present invention) After attaching Zn as a functionalized metal to the surface of a high carbon steel wire by electroplating, re-drawing was performed.
An electrode wire material having a cross-sectional area equal to the area of a circle with a diameter of 50 μlφ by twisting together a plurality of wires with a plating thickness of 5 μm after redrawing and adding a tensile strength of 5 kgf/mm2.

(Comparative Example 1) As a comparative material, a conventionally used tungsten electrode wire having a diameter of 50 μmφ and a tensile strength of 120 kgf/mta2 was used.

The one according to the present invention example 2 and the one according to the present invention example 4,
Although there is no big difference in the processing properties of these three, they are better than the others, and the one shown in Inventive Example 3 shows the second most excellent processing properties. Although the material according to Inventive Example 1 is inferior to 2.3.4, it exhibits better processing characteristics than when processed using a conventional tungsten electrode material (Comparative Example 1). In particular, these four examples of the present invention have a remarkable effect of improving characteristics when the workpiece is thick.

Among these three processing characteristics, the electrode wire according to the present invention exhibits the greatest improvement in processing accuracy.

Although there is no significant difference in processing characteristics between the products according to Example 2 of the present invention and those according to Example 4 of the present invention, as described above, the product according to Example 4 of the present invention is the most economical.

Since the electrode material shown in this embodiment is mainly made of Fe, it is much cheaper than the conventional tungsten 1Jjii material.

Moreover, this example shows an example, and effects equivalent to or better than those of this example were obtained also with respect to electrode wires produced under other conditions within the scope of the present invention.

(Example 2 and Comparative Example 2) As shown in Table 1, electrode wires of Invention Examples 5 to 8 and Comparative Example 2 were produced as follows.

(Example 5 of the present invention) An electrode wire having a cross-sectional area equal to the area of a circle with a diameter of 200 μmφ by twisting together a plurality of Fe-based wires with a tensile strength of 130 kgf/mm2.

(Example 6 of the present invention) Zn with a thickness of 10 μm was attached as a functional metal to the wire of Example 5 of the present invention by electroplating, and then a plurality of these wires were twisted to make the area equal to the area of a circle with a diameter of 200 μlφ. Electrode wire with a cross-sectional area.

(Example 7 of the present invention) A plurality of wires of Example 5 of the present invention are twisted together to have a diameter of 180μ.
An electrode wire material in which Zn as a functionalized metal is adhered to the surface along the outer periphery of a stranded wire having a cross-sectional area equal to the area of a circle of lφ with an average thickness of 10 μm11 by electroplating.

(Example 8 of the present invention) Zn was deposited as a functional metal on the surface of an inexpensive high-carbon wire with a lower carbon content than the wire used in Example 7 of the present invention by electroplating, and then redrawn. 130k
An electrode wire material having a cross-sectional area equal to the area of a circle with a diameter of 200 μlφ by twisting together a plurality of wires with a plating thickness of 10 μm after redrawing and adding a tensile strength of gf/am2.

(Comparative Example 2) As comparative materials, conventionally used diameter 200μmφ,
A brass wire with a tensile strength of 95 kgf/mff12 was used.

The one according to the present invention example 6 and the one according to the present invention example 8,
Although there is no major difference in the processing characteristics of these three examples, better results than the other examples were obtained, and the one shown in Inventive Example 7 shows the second most excellent processing characteristics.

Invention Example 5 is inferior to the others, but exhibits much better processing characteristics than Comparative Example 2 when processed using conventional brass wire. In particular, these four materials according to the present invention have a remarkable effect of improving characteristics when the material is thick.

Further, among these three processing characteristics, the electrode wire according to the present invention shows the most excellent improvement in processing speed.

Although there is no major difference in processing characteristics between Invention Example 6 and Invention Example 8, as described above, Invention Example 8
is the most economical case.

Since the material shown in this example is mainly made of Fe, it is much cheaper than conventional brass electrode materials.

Further, this example is merely an example, and effects equivalent to or better than those of this example were obtained with electrode wires produced under other conditions within the scope of the present invention.

<Effects of the Invention> The electrode wire of the present invention is composed of a plurality of wires twisted together, and a functionalized metal is attached to its surface by an appropriate method in order to further improve processing characteristics. Therefore, compared to conventional wires, the machining speed is higher, the line runout is reduced, the "tension amount" can be reduced, and both the machined surface roughness and the machined groove width can be reduced.

In addition, the bends are small and the wire is strong, so automatic wire connection is easy, and the frequency of wire breakage is low, which greatly improves work efficiency.

Economically, the cost is less than 1/10 that of conventional tungsten wire and less than 2/3 of that of brass wire, making it a success in this respect as well.

In particular, the effective flow of machining fluid and the electric discharge effect when an uneven cross section passes through the machining tip provide remarkable machining characteristics for thick workpieces. It is possible to realize the improvement effect of

[Brief explanation of drawings]

Figures 1, 3, and 5 show the machining accuracy characteristics, machining speed characteristics, and machined surface roughness measurements during the first machining of the electrode wire of the present invention in Example 1, respectively, compared with the conventional electrode wire. This is a graph shown. Figures 2, 4, and 6 compare the machining accuracy characteristics, machining speed characteristics, and machined surface roughness measurements during first machining of the electrode wire of the present invention in Example 2, respectively, with the conventional electrode wire. This is a graph shown as follows.

Claims (9)

[Claims] (1) An electrode wire for wire electrical discharge machining characterized by having a plurality of metal wires. (2) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 1, wherein the electrode wire has a cross-sectional area equal to a circular area of 10 to 300 μmφ. (3) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 1, wherein the electrode wire has a cross-sectional area equal to a circular area of 30 to 500 μmφ. (4) An electrode wire material for wire electrical discharge machining, characterized in that it consists of at least one metal wire to which a functionalized metal is adhered so as to have an adhesion thickness of 0.1 μm or more. (5) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 4, wherein the electrode wire has a cross-sectional area equal to a circular area of 10 to 300 μmφ. (6) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 4, wherein the electrode wire has a cross-sectional area equal to a circular area of 30 to 500 μmφ. (7) An electrode wire material for wire electric discharge machining, characterized in that a functionalized metal is adhered to strands of metal wires to a thickness of 0.1 μm or more. (8) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 7, wherein the electrode wire has a cross-sectional area equal to a circular area of 10 to 300 μmφ. (9) The tensile strength of the metal wire is 150 kgf/mm^2
The electrode wire for wire electrical discharge machining according to claim 7, wherein the electrode wire has a cross-sectional area equal to a circular area of 30 to 500 μmφ.