JP2005254408A - Electrode wire for electric discharge machining, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved electrode wire for electric discharge machining. <P>SOLUTION: The electrode wire for electric discharge machining includes a core, and one or more kinds of covered layers covering an outer peripheral surface of the core. The core and one or more kinds of the covered layers have different materials, Each of the one or more kinds of the covered layers is made of metal selected from a group composed of Cu, Sn, Ag, Zn, Cs, Mg, and In or alloy including the metal. Granular substances made of the different material is scattered on a surface of at least one layer of the one or more of the covered layers. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to improvement of an electrode wire used for wire electric discharge machining.

Wire EDM is a work piece that causes intermittent discharge between a linear work electrode called wire EDM electrode wire and a work piece through a working fluid such as water or oil. Is a method of melting and cutting a workpiece into a desired shape by moving the wire relative to the electrode wire for wire electric discharge machining. This method is used for manufacturing various molds. In such wire electric discharge machining, the finished machining accuracy and finished surface condition of the workpiece are good, the substance from the electrode wire does not adhere to the workpiece, the electric discharge machining time is short, etc. Electrical discharge machining characteristics are required. And as an electrode wire for electric discharge machining used for such wire electric discharge machining, a brass wire has been conventionally used because it has excellent wire drawing workability and strength as an electrode wire.
JP 2001-150247 A

  Recently, an electrode wire capable of improving the electric discharge machining speed and accuracy has been desired along with the improvement of the machining power source. In particular, in the case of using a power source of a wire electric discharge machine that applies a high voltage and a pulse repetition voltage for a short time, an electrode wire capable of increasing the electric discharge machining speed and accuracy is desired.

  However, a sufficiently high electric discharge machining speed could not be obtained with an electrode wire for electric discharge machining using a conventional brass wire. Brass wires also have the disadvantages that the amount of material adhering from the electrode wire to the workpiece is large, the cut surface properties of the workpiece are rough, and the electrode wire is likely to break if electric discharge machining is attempted at high speed. It was.

  In addition, a core material made of Cu or Cu alloy is coated with a Zn layer, or a heat treatment is performed after the Zn layer is coated, and a Cu—Zn alloy is formed on the surface layer of the core material by diffusion, and an oxide film is formed on the outermost surface thereof. Some wire electric discharge machining electrode wires are also used. However, in the former, the cut surface property of the workpiece is improved, but a sufficiently high electric discharge machining speed cannot be obtained. In the latter, the electric discharge machining speed is improved to some extent, but the cut surface property of the workpiece is sufficiently improved. There was a problem that the electrode wire was not easily positioned before starting electric discharge machining. Furthermore, the conventional wire electric discharge machining electrode wire provided with a core material and a coating layer formed on the outer periphery of the core material has improved electric discharge machining characteristics as compared with the brass wire, but the electrode wire itself and the feed guide However, there is a problem that the wear damage of the guide dies is severe, the life is shortened, and the electric discharge machining cost is considerably increased.

  Therefore, the object of the present invention is for wire electric discharge machining, which can shorten the electric discharge machining time, makes it difficult for substances from the electrode wires to adhere to the workpiece, and further smoothes the cut surface properties of the workpiece. It is to provide electrode wires at a low price. The present invention also provides an electrode wire for wire electric discharge machining that can easily position the electrode wire and can reduce the electric discharge machining cost comprehensively without shortening the life of the power feed guide and guide guide die. It is also aimed to do.

  According to the present invention, an electrode wire for wire electric discharge machining includes a core material and one or more types of coating layers covering the outer peripheral surface of the core material, and the core material and the one or more types of coating layers are different from each other. Each of the one or more coating layers is made of a metal selected from the group consisting of Cu, Sn, Ag, Zn, Cs, Mg, and In or an alloy containing the metal. It is characterized in that granular materials of different materials are dispersed on at least one surface of the layer.

  In this way, the dispersal of particulate materials of different materials on the surface of the coating layer makes it easy to suppress localized concentrated discharge and maintain a fine and frequent discharge, and the electric discharge machining time. It has been found that the material from the electrode wire is less likely to adhere to the workpiece and that the cut surface properties of the workpiece are smooth.

  In addition, the shape of the granular material may be any shape other than a spherical shape or a polygonal shape. The average particle diameter of the granular material is preferably 1/3000 or more and less than 1/10 of the wire diameter of the electrode wire. This is because if the diameter of the granular material is less than 1/3000 of the wire diameter of the electrode wire, the effect of increasing the processing speed is small, and if it is 1/10 or more, the effect of increasing the speed is saturated and the feed guide or guide guide die is This is because it adversely affects the service life.

  The first coating layer in direct contact with the outer peripheral surface of the core material is preferably made of a Cu—Zn alloy, and it is preferable that granular materials of different materials are dispersed on the surface of the coating layer. Moreover, it is preferable that a granular material consists of a Cu-Zn alloy and the Zn density | concentration of this alloy is higher than the Zn density | concentration of a 1st coating layer. Furthermore, it is preferable that the first coating layer is a Cu-37 to 55% by mass Zn alloy and the particulate material is a Cu-49 to 70% by mass Zn alloy. Furthermore, it is preferable that the particulate material includes at least one of a β phase and a β ′ phase of a Cu—Zn alloy and a γ phase. This is because if the Zn concentration of the Cu—Zn alloy of the first coating layer is less than 37% by mass, the effect of speeding up is small, and if it exceeds 55% by mass, it becomes difficult to draw into a thin wire and the cost increases. Because. Also, if the Zn concentration of the Cu—Zn alloy, which is a granular material, is less than 49% by mass, the effect of increasing the speed is small, and if it exceeds 70% by mass, the effect of increasing the speed is saturated and the life of the power feed guide and guide guide die is adversely affected. Because it gives. The particulate material preferably includes at least one of a β phase and a β ′ phase of a Cu—Zn alloy and a γ phase, but may be Cu, Zn, or an oxide of a Cu—Zn alloy.

  Furthermore, when the outermost layer of the one or more kinds of coating layers is a metal or alloy selected from the group consisting of Ag, Sn, Cs, Zn, Cu, and Cu—Zn alloy, the effect of speeding up is more excellent. It was found that In this case, since the outermost layer has characteristics such as being easily vaporized at the time of discharge or having excellent thermal conductivity, it can act to suppress the temperature rise during discharge of the electrode wire. It is considered that higher-speed electric discharge machining can be performed without causing disconnection of the electrode wire even under severe electric discharge machining conditions. In addition, if the outermost layer of a plurality of coating layers is formed of a metal or alloy, a compound coating layer having a high hardness generally does not shorten the service life by promoting wear and damage of the power supply guide and guide guide die, and reducing the life. The positioning operation of the electrode wire before starting the processing can be easily performed. The outermost layer may be a continuous layer or a discontinuous layer. The maximum thickness of the outermost layer is preferably 1/6000 or more and less than 1/40 of the wire diameter of the electrode wire. This is because when the maximum thickness of the outermost layer is less than 1/6000, the effect of increasing the speed is small, and when it is 1/40 or more, the effect of increasing the speed is saturated.

  Furthermore, if the area ratio of the particulate matter in one or more kinds of coating layers in the cross section of the electrode wire is 0.05% or more and less than 30%, both high-speed machining and surface smoothness of the workpiece are more compatible. Can be made. That is, if the area ratio of the particulate material in one or more kinds of coating layers is less than 0.05%, the effect of increasing the speed is not sufficient, and if it exceeds 30%, the effect of smoothing the surface becomes insufficient.

  Regarding the method of manufacturing the above-mentioned electrode wire for wire electric discharge machining, the core material is made of a metal selected from the group consisting of Cu, Sn, Ag, Zn, Cs, Mg, and In or an alloy containing the metal. By passing through the process of forming the above coating layer and the process of dispersing granular materials of different materials on at least one surface of the formed coating layer, the electrical discharge machining time can be shortened, and from the electrode wire It has been found that an electrode wire for wire electric discharge machining can be provided at a low price, since the substance is less likely to adhere to the workpiece and the cut surface properties of the workpiece are smooth.

  More specifically, at least one kind of a coating layer of a metal selected from the group consisting of Sn, In, Zn, and Mg or an alloy containing the same is formed on the outer peripheral surface of the core material containing Cu in the surface layer. A manufacturing method including a step of forming a plurality of diffusion layers by heat treatment, and a step of performing wire drawing after that can be applied.

  In the step of forming one or more metal or alloy coating layers on the core material before the heat treatment, it is preferable to form a Zn layer as the coating layer in direct contact with the core material. In the step of forming a plurality of diffusion layers, it is preferable that at least one of the formed diffusion layers includes a β phase and a γ phase or a β ′ phase and a γ phase. Further, after the step of forming a plurality of diffusion layers, the method further includes the step of further forming one or more coating layers made of a metal selected from the group consisting of Sn, Ag, Zn, and Cs or an alloy containing the same. Is preferred.

  That is, in the present invention, when producing an electrode wire by dispersing particles of different materials, a phase with low workability is formed by a thermal diffusion reaction, and the phase with low workability is formed by the next wire drawing step. It has been found that it is possible to subdivide and disperse as particulates. Furthermore, it has been found that if a material layer having good workability is formed on the surface of a diffusion reaction phase having low workability, it is possible to more uniformly disperse the particulate matter during wire drawing.

  Hereinafter, various examples will be described as more specific examples of the embodiment of the present invention.

(Example 1)
Prepare a material in which a Zn layer is plated to a thickness of about 35 μm on a Cu-0.5 mass% Sn alloy core with a wire diameter of 0.8 mmφ, and a Mg layer is further plated to a thickness of about 5 μm. Was subjected to diffusion heat treatment at 400 ° C. for 30 hours. By this diffusion heat treatment, a Cu—about 40 mass% Zn layer and an Mg—about 50 mass% Zn layer thereon were formed on the core material, and the Mg layer did not remain.

  The diffusion-heat treated material was plated with a Sn layer having a thickness of about 5 μm, and then drawn to 0.2 mmφ. The structural characteristics of the electrode wire of Example 1 obtained in this way are shown in Table 1. Summarized as one feature.

As can be seen from Table 1, the outermost thin Sn layer was discontinuous as a result of being drawn by wire drawing. Further, the Mg—about 50 mass% Zn layer had a hard and brittle nature, and was pulverized by wire drawing into a granular material. According to the phase diagram of the Mg—Zn alloy, it is shown that an Mg ₇ Zn ₃ intermetallic compound can be formed in a composition region near about 50 mass% Zn. In general, intermetallic compounds are hard and brittle.

  In addition, the particle size of the granular material was measured as follows. First, the cross section of the electrode wire is observed with a microscope, and the cross sectional area of each particle is measured by image processing. Then, the diameter of a circle having an area corresponding to the cross-sectional area of the particle was obtained, and this was regarded as the particle size.

  The “ratio” relating to the granular substance in Table 1 represents the area ratio of the granular substance in the area of all the coating layers formed on the core material in the cross section of the electrode wire.

(Example 2)
A material in which a Zn layer was formed to a thickness of about 40 μm on a copper-coated steel wire core material having a wire diameter of 0.9 mmφ was prepared, and subjected to heat treatment at 380 ° C. for 50 hours. By this heat treatment, a Cu—about 35 mass% Zn layer, a Cu—about 45 mass% Zn layer, and a Cu—about 50 mass% Zn layer were formed in this order on the core material.

  The heat-treated material was plated with an Ag layer having a thickness of about 2 μm, and then drawn to 0.2 mmφ. The structural characteristics of the electrode wire of Example 2 obtained in this way are also shown in Table 1. It is summarized as two features.

As can be seen from Table 1, the Cu—about 50 mass% Zn layer had a hard and brittle nature and was pulverized by wire drawing into a particulate material. Note that the phase diagram of the Cu—Zn alloy shows that the γ phase can be mixed in the β phase and / or the β ′ phase in the composition region in the vicinity of about 50 mass% Zn. Here, the β ′ layer has the same composition as the β layer, but is in a regular lattice state, and has a harder property than the β phase. The γ layer is a phase mainly composed of a Cu ₅ Zn ₈ intermetallic compound, and is known to have a harder and more brittle property than the β ′ layer.

(Example 3)
A material in which a Zn layer was formed to a thickness of about 50 μm on a Cu-20 mass% Zn alloy core material having a wire diameter of 1.0 mmφ was prepared, and this was maintained at 850 ° C. for 90 seconds and then subjected to a heat treatment for rapid cooling. In this heat treatment, the material was passed through the furnace set at 850 ° C. for 90 seconds, and then the material was cooled with water. By this heat treatment, a Cu—about 45 mass% Zn layer and a Cu—about 59 mass% Zn layer were formed in this order on the core material.

  The heat-treated material was drawn to 0.2 mmφ without any additional plating layer on the surface. The structural characteristics of the electrode wire of Example 3 obtained in this way are also shown in Table 1. 3 features are summarized. In Example 3, the Cu—about 59 mass% Zn layer consists only of a hard and brittle γ phase.

Example 4
A material in which a Zn layer was plated to a thickness of about 38 μm on a Cu-20 mass% Zn alloy core material having a wire diameter of 0.8 mmφ was prepared, and subjected to heat treatment at 390 ° C. for 45 hours. By this heat treatment, a Cu—about 45 mass% Zn layer and a Cu—about 65 mass% Zn layer were formed in this order on the core material.

  The heat-treated material was plated with a Zn layer having a thickness of about 10 μm, and then drawn to 0.2 mmφ. The structural characteristics of the electrode wire of Example 4 obtained in this way are also shown in Table 1. 4 features are summarized. Also in Example 4, the Cu—about 65 mass% Zn layer is composed of only a hard and brittle γ phase.

(Example 5)
A material in which a Zn layer was plated to a thickness of about 40 μm on a Cu-20 mass% Zn alloy core material having a wire diameter of 0.8 mmφ was prepared, and this was maintained at 870 ° C. for 60 seconds and then subjected to heat treatment for rapid cooling. By this heat treatment, a Cu—about 45 mass% Zn layer and a Cu—about 55 mass% Zn layer were formed in this order on the core material.

  The heat-treated material was plated with a Zn layer having a thickness of about 10 μm, and then drawn to 0.3 mmφ. The structural characteristics of the electrode wire of Example 5 obtained in this way are also shown in Table 1. Summarized as 5 features. In Example 5, the Cu—about 55 mass% Zn layer is composed of a β phase and / or a β ′ phase and a γ phase.

(Example 6)
A material in which a copper layer having a thickness of 10 μm and a Zn layer having a thickness of 10 μm on the steel wire core material having a wire diameter of 0.2 mmφ was prepared, and heat treatment was performed at 380 ° C. for 10 hours. By this heat treatment, a Cu—about 38 mass% Zn layer and a Cu—about 49 mass% Zn layer were formed in this order on the core material.

  The heat-treated material was drawn to 0.05 mmφ without any additional plating layer on the surface. The structural characteristics of the electrode wire of Example 6 obtained in this way are also shown in Table 1. 6 features are summarized. Among the particulate material Cu of about 49 mass% Zn in Example 6, a small amount of γ phase can be mixed in the β phase and / or β ′ phase.

(Conventional example)
An electrode wire for electric discharge machining of Cu-35.2 mass% Zn, which is an example of the electrode wire according to the conventional example and does not have a coating layer, was adopted as an object for comparison with the electrode wire according to the present invention.

  Note that, in any of the above-described various embodiments and the electrode wires according to the conventional example, a light energization heat treatment is performed after the wire drawing in order to eliminate wire wrinkles due to the influence of plastic working (wire drawing). The electrode wires finally obtained in each example were all excellent in straightness with smooth surfaces and no wrinkles.

  The electrode wire shown in Table 1 is attached to a wire electric discharge machine, and electric discharge machining is performed under the same conditions. Electric discharge machining speed, amount of deposit on the cut surface of the workpiece, surface property of the workpiece, electrode wire Table 2 shows the number of disconnections, the service life of the power supply guide and guide guide die, and the automatic feedability at the time of disconnection. The electric discharge machining speed is obtained as a cross-sectional area per unit time (the product of the machining feed rate and the workpiece thickness), and then the ratio of the electric discharge machining speed by the conventional electrode as 1.0 as a reference. It is shown. Moreover, the amount of deposits on the cut surface of the workpiece is also shown in a relative ratio of 100 when a conventional electrode wire is used. Further, the lifespan of the power supply guide and the guide guide die is also shown in a relative ratio where the case where the conventional electrode wire is used is 100. In addition, the SKD-11 material in JIS standard was used as a workpiece, and the thickness was 60 mm.

  As can be seen from Tables 1 and 2, the electrical discharge machining electrode wire according to the present invention has significantly improved electrical discharge machining characteristics (machining speed, surface properties of the workpiece, etc.) compared to the conventional one, and automatic wire feeding. In addition, the electrode wire can be easily positioned, and the electric discharge machining cost can be reduced comprehensively without shortening the life of the power supply guide and the guide guide die.

  Note that the effect of the present invention can be exhibited to the same extent or more even when the electrode wire includes a granular material made of an oxide of Cu, Zn, or a Cu-Zn alloy instead of the above-described granular material. . Such an oxide particulate material can be formed by forming any layer of Cu, Zn, and Cu—Zn alloy, then heat-treating in an oxidizing atmosphere, and then drawing.

Claims (16)

A core material,
One or more coating layers covering the outer peripheral surface of the core material,
The core material and the one or more coating layers have different materials from each other,
Each of the one or more coating layers is made of a metal selected from the group consisting of Cu, Sn, Ag, Zn, Cs, Mg, and In or an alloy containing the metal,
An electrode wire for wire electric discharge machining, wherein granular materials of different materials are dispersed on at least one surface of the one or more types of coating layers.   2. The electrode wire for wire electric discharge machining according to claim 1, wherein an average particle diameter of the granular material is 1/3000 or more and less than 1/10 of the wire diameter of the electrode wire.   The first coating layer that is in direct contact with the outer peripheral surface of the core material is made of a Cu-Zn alloy, and granular materials of different materials are dispersed on the surface of the first coating layer. Item 3. The electrode wire for wire electric discharge machining according to Item 1 or 2.   4. The electrode wire for wire electric discharge machining according to claim 3, wherein the particulate material is made of a Cu—Zn alloy, and the Zn concentration of the alloy is higher than the Zn concentration of the first coating layer.   5. The electrode wire for wire electric discharge machining according to claim 4, wherein the first coating layer is a Cu-37 to 55 wt% Zn alloy and the particulate material is a Cu-49 to 70 wt% Zn alloy.   6. The wire electric discharge machining electrode wire according to claim 4, wherein the particulate material includes at least one of a β phase and a β ′ phase and a γ phase.   4. The wire electric discharge machining electrode wire according to claim 3, wherein the particulate material is an oxide of Cu, Zn, or a Cu—Zn alloy.   The outermost layer of the one or more kinds of coating layers is a metal or alloy selected from the group consisting of Ag, Sn, Cs, Zn, Cu, and a Cu-Zn alloy. An electrode wire for wire electric discharge machining according to claim 1.   The electrode wire for wire electric discharge machining according to claim 8, wherein the outermost layer is a discontinuous body.   The electrode wire for wire electric discharge machining according to claim 8 or 9, wherein the maximum thickness of the outermost layer is 1/6000 or more and less than 1/40 of the wire diameter of the electrode wire.   10. The area ratio of the granular material occupying in the one or more types of coating layers in a cross section of the electrode wire is 0.05% or more and less than 30%. Electrode wire for wire electrical discharge machining.   It is a method for manufacturing the electrode wire for wire electric discharge machining of Claim 1, Comprising: From the group which consists of Cu, Sn, Ag, Zn, Cs, Mg, P, and In on the outer peripheral surface of the said core material Forming at least one coating layer of a selected metal or an alloy containing the metal, and dispersing granular materials of different materials on at least one layer of the one or more coating layers. A method for producing a wire electric discharge machining electrode wire.   It is a method for manufacturing the electrode wire for wire electric discharge machining of Claim 1, Comprising: It selects from the group which consists of Sn, In, Zn, and Mg on the outer peripheral surface of the said core material which contains Cu at least in a surface layer A step of forming one or more coating layers of the formed metal or an alloy containing the metal, a step of subsequently forming a plurality of diffusion layers by heat treatment, and a step of performing wire drawing after that The manufacturing method of the electrode wire for wire electric discharge machining.   The Zn layer is formed as a coating layer in direct contact with the core material in the step of forming the one or more metal or alloy coating layers on the core material before the heat treatment. The manufacturing method of the electrode wire for wire electric discharge machining of description.   The method of manufacturing an electrode wire for wire electric discharge machining according to claim 13 or 14, wherein at least one of the diffusion layers includes at least one of a β phase and a β 'phase and a γ phase. After the step of forming the plurality of diffusion layers, the method further includes the step of forming one or more coating layers of a metal selected from the group consisting of Sn, Ag, Zn, and Cs or an alloy containing the metal, and thereafter The method of manufacturing an electrode wire for wire electric discharge machining according to any one of claims 13 to 15, wherein the wire drawing process is performed on the wire.