JP2007136579A - Covered electrode wire for wire discharge machining, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a covered electrode wire for wire discharge machining, having proper conductivity and discharge machining performance, and to provide a manufacturing method for it. <P>SOLUTION: This covered electrode wire 6 for wire discharge machining includes two or more covering layers 2, 3, 4, 5 on the outer periphery of a core material 1, where the wire is a quadrangle and rounded circular corner parts R are provided at the outer peripheral corner parts. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode wire for wire electric discharge machining, and more particularly to a coated electrode wire for wire electric discharge machining.

  As a general electrode wire for wire electric discharge machining, an electrode wire having a circular cross section made of a single Cu—Zn alloy is used. This electrode wire has excellent discharge characteristics such as processing speed and processing accuracy, and has advantageous characteristics in terms of cost. In order to further improve the electric discharge machining speed and machining accuracy of this type of electrode wire, it is desirable to form the electrode wire from a Cu—Zn alloy having a high Zn concentration. However, if the Zn concentration in the Cu-Zn alloy exceeds 40% by weight, the wire drawing processability is remarkably lowered and it becomes difficult to produce an electrode wire. Therefore, a Cu-Zn alloy having a Zn concentration of 40% by weight or less is obtained. Have been used.

  In recent years, high-speed workability of electrode wires for wire electric discharge machining has been emphasized. For this reason, a coated electric discharge machining electrode wire is proposed in which a Cu-Zn alloy layer having a higher Zn concentration than before is coated around a core material made of a Cu alloy such as a Cu-2.0 wt% Sn alloy. (For example, refer to Patent Document 1).

  Further, as a method for forming a coating layer having a high Zn concentration on the surface of the core material, various methods for applying Zn plating to the surface of the core material have been proposed (for example, see Patent Document 2).

  Moreover, there exists a Cu-Zr alloy as one of the copper alloys with high high temperature tensile strength. As a coated electrode wire for electric discharge machining using this Cu-Zr alloy, a Cu-38% to 50% weight Zn alloy layer is formed on the outer periphery of a core material made of Cu-0.05 to 0.2% by weight Zr alloy. What was formed is mentioned (for example, refer patent document 3).

Japanese Patent Laid-Open No. 5-339664 JP-A-6-190635 Japanese Patent Laid-Open No. 9-225748

  It is said that the temperature of the electrode wire for electric discharge machining generally rises to 200 ° C. to 400 ° C. during electric discharge machining, and a thermal load is applied to the electrode wire itself, while tension load for increasing the machining speed and machining accuracy is also applied. Therefore, it is required to have high tensile strength and conductivity at high temperatures.

  However, generally used coated electrode wires are not high in strength and conductivity at high temperatures, and therefore disconnection occurs when the processing speed is further increased. Since the electrode wire for electric discharge machining described in Patent Document 3 uses a Cu-Zr material having a high high-temperature tensile strength as a core material, the high-temperature tensile strength is increased, but the conductivity contributing to heat resistance and the high Zn concentration are increased. The balance to obtain was difficult, and the processing speed could not be increased greatly.

  In addition, since the electrode wire for electric discharge machining described in Patent Document 2 described above has a coating layer having a high Zn concentration on the surface of the core material, the processing accuracy is improved, but a layer of a pure Zn layer formed by Zn plating. Since the thickness is small, the pure Zn layer evaporates instantaneously during electric discharge machining, and there is a problem that a sufficient improvement in electric discharge machining speed cannot be expected.

  An object of the present invention, which was created in view of the above circumstances, is to provide a coated electrode wire for wire electric discharge machining having good conductivity and electric discharge machining performance and a method for producing the same.

  The present invention provides a coated electrode wire that has better conductivity than the conventional material, has a wide instantaneous discharge range, and has a coating layer with a high Zn concentration. Therefore, compared with the conventional material, discharge performance, disconnection limit, electric discharge machining speed An object of the present invention is to provide a coated electrode wire for electric discharge machining that is improved significantly and has good machining accuracy and surface accuracy.

  In order to achieve the above-mentioned object, the invention of claim 1 is a coated electrode wire for wire electric discharge machining having two or more coating layers on the outer periphery of a core material. It is a covered electrode wire for wire electric discharge machining characterized by having a portion.

  According to a second aspect of the present invention, there is provided a coated electrode wire for wire electric discharge machining according to the first aspect, wherein the core material is eccentrically disposed on a side surface of the electrode wire, and three side surfaces excluding the side surface on the eccentric side are used as an electric discharge machining surface. It is.

  According to a third aspect of the present invention, the coating layer has a pure Zn layer on the inner layer side and an alloy layer on the outer layer side, and a Cu-Zn system is formed at the interface between the core material and the pure Zn layer and at the interface between the pure Zn layer and the alloy layer. The coated electrode wire for wire electric discharge machining according to claim 1 or 2, wherein each has a reaction layer of an intermetallic compound.

  According to a fourth aspect of the present invention, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode wire is 0.05 to 0.25, the layer thicknesses t1 and t2 of the reaction layers and the entire electrode wire 4. The coated electrode wire for wire electrical discharge machining according to claim 1, wherein the ratio of the length a to the long side a is 0.002 to 0.005. 5.

  In the invention of claim 5, the thickness t3 of the coating layer on the side where the core material is eccentric is thinner than the thickness t4 of the coating layer on the opposite side, and the ratio of t3 / t4 is 0.2 to 0.8. A coated electrode wire for wire electric discharge machining according to any one of claims 1 to 4.

  The invention according to claim 6 is that each of the reaction layers is a layer in which the Zn concentration is inclined, and the reaction layer at the interface between the core material and the pure Zn layer has a Zn concentration continuously increasing from the inside toward the outside, Conversely, the reaction layer at the interface between the pure Zn layer and the alloy layer is the coated electrode wire for wire electric discharge machining according to any one of claims 1 to 5, wherein the Zn concentration continuously decreases from the inside toward the outside. .

  The invention according to claim 7 is the wire discharge according to any one of claims 1 to 6, wherein the coating layer has a pure Zn layer on the inner layer side and an alloy layer having a composition of Cu-30 to 46 wt% Zn on the outer layer side. This is a coated electrode wire for processing.

  The invention according to claim 8 is the coated electrode wire for wire electric discharge machining according to any one of claims 3 to 7, wherein each of the reaction layers is made of an intermetallic compound having a composition of Cu-60 to 90 wt% Zn.

The invention of claim 9 is characterized in that the core material is
Pure Cu,
Cu-0.02-0.2 wt% Zr alloy,
Cu-0.15-0.70 wt% In alloy,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy,
Cu-0.15-0.70 wt% Sn alloy,
Cu-5-30 wt% Zn alloy,
Cu-0.2-20 wt% Ag alloy,
An alloy obtained by adding at least one of Zr, Cr, Mg, Al, Si, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Or an Fe-based alloy,
A coated electrode wire for wire electric discharge machining according to any one of claims 1 to 8, comprising:

  The invention according to claim 10 is a method of manufacturing a coated electrode wire for wire electric discharge machining having two or more coating layers on the outer periphery of the core material, and after forming the coating layer on the outer periphery of the core material having a quadrangular cross section, a diffusion treatment by heat treatment And a surface treatment to diffuse atoms at the interface between the core material and the coating layer and between the coating layers, and to rearrange them, thereby forming a reaction layer at each interface. It is a manufacturing method of the coated electrode wire for processing.

  According to the eleventh aspect of the present invention, a pure Zn layer is first provided on the outer periphery of the core material, and an alloy layer having a composition of Cu-30 to 46 wt% Zn is provided around the pure Zn layer, and then the heat treatment is performed. Item 11. A method for producing a coated electrode wire for wire electrical discharge machining according to Item 10.

  The invention of claim 12 performs a surface plasma heat treatment on the core material coated with the coating layer in order to perform a good wire drawing process, heat-treats only the hard surface high Zn concentration alloy layer, The method for producing a coated electrode wire for wire electric discharge machining according to claim 10 or 11, wherein heat treatment is not performed.

  According to the invention of claim 13, the core material coated with the coating layer is caused to travel in the lateral direction, the pure Zn layer having a low intermediate melting temperature is melted in a short time by the plasma heat treatment technique, and the core material of the center is made of gravity. The coated electrode wire for wire electric discharge machining according to any one of claims 10 to 12, wherein the core material is sunk downward by operation to decenter the core material on a side surface of the electrode wire, and a coating layer having a non-uniform thickness is formed around the core material. It is a manufacturing method.

  Since the coated electrode wire for wire electric discharge machining according to the present invention is a rectangular electrode wire in which a reaction layer is provided at the interface between the core material having a square cross section and the pure Zn layer and at the interface between the pure Zn layer and the Cu-Zn alloy layer. The excellent electrical discharge machining performance is exhibited.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view of a coated electrode wire for wire electric discharge machining according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the coated electrode wire 6 for wire electric discharge machining according to the present embodiment has a square cross section in which a reaction layer 4, a pure Zn layer 2, a reaction layer 5, and an alloy layer 3 are sequentially provided on the outer periphery of the core material 1. It is a covered electrode wire having a shape. The reaction layer 4, the pure Zn layer 2, the reaction layer 5 and the alloy layer 3 constitute two or more coating layers. The electrode wire 6 has an R-shaped circular corner R at the outer peripheral corner.

  The thickness of the coating layer is such that the thickness t3 of the coating layer on one side (a side surface (the lower surface in FIG. 1)) is the coating layer on the three side (the surface on the opposite side of the certain side surface (the upper surface in FIG. 1)). It is thinner than t4 (t3 <t4), and the ratio of t3 / t4 is in the range of 0.2 to 0.8, and is adjusted according to requirements such as processing accuracy and high-temperature tensile strength of the wire. Further, the pure Zn layer 2 is thicker than the alloy layer 3.

  The alloy layer 3 is made of an alloy having a composition of Cu-30 to 46 wt% Zn, and the reaction layers 4 and 5 are made of an intermetallic compound having a composition of Cu-60 to 90 wt% Zn. The components and compositions of the layers 4, 5, and 3 are adjusted according to requirements such as accuracy.

  The ratio of the thickness of the coating layer to the length of the long side of the entire electrode wire 6 (the height of the side surface adjacent to the side surface with the electrode wire 6) a is 0.05 to 0.25, and the reaction layers 4 and 5 The core material 1 is formed so that the ratio of the layer thickness t1, t2 (layer thickness in the short side b direction of the entire electrode wire 6) to the long side length a of the entire electrode wire 6 is 0.002 to 0.005. The size and the layer thickness of each layer 4, 2, 5, 3 are adjusted.

  The relationship between the distance P (P1 to P2, P3 to P4) from the inside to the outside in the thickness direction of each reaction layer 4 and 5 and the Zn concentration is shown in FIGS. 3 (a) and 3 (b). The Zn concentration of the layer 4 is a gradient layer that continuously increases from C1 to C2 from the inside to the outside of the coating layer. Moreover, as shown in FIG.3 (b), the Zn density | concentration of the reaction layer 5 is a gradient layer which decreases continuously with C3-C4 toward the outer side from the inner side of a coating layer. As a result, from the viewpoint of the structure, the electrode wire 6 is a wire rod in which the core material 1 and the layers 2 and 3 are integrated via the reaction layers 4 and 5.

The constituent material of the core material 1 is not particularly limited as long as the material has high conductivity, high strength, and high temperature strength.
Pure copper,
Cu-0.02-0.2 wt% Zr alloy,
Cu-0.15-0.70 wt% In alloy,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy,
Cu-0.15-0.70 wt% Sn alloy,
Cu-5-30 wt% Zn alloy,
Cu-0.2-20 wt% Ag alloy,
An alloy obtained by adding at least one of Zr, Cr, Mg, Al, Si, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Or an Fe-based alloy,
Is mentioned.

  The reason why the Zn concentration of the alloy layer 3 is set to 32 to 46% by weight is that when the Zn concentration is less than 32% by weight, the effect of improving the electric discharge machining speed cannot be sufficiently obtained. This is because the wire drawing workability is remarkably deteriorated.

  The ratio between the layer thickness of the coating layer and the length a of the long side of the entire electrode wire 6 is set to 0.05 to 0.25. This is because they are consumed, and a sufficient improvement in electric discharge machining speed and improvement in machining accuracy cannot be expected. On the other hand, if it exceeds 0.25, the cross-sectional area of the coating layer occupying the entire electrode wire 6 increases, leading to a decrease in the high-temperature strength and conductivity of the electrode wire 6, and a sufficient improvement in electric discharge machining speed can be expected. This is because it disappears.

  In the rectangular electrode line, the thickness t3 of the one-side coating layer is thinner than the three-side coating layer t4. The ratio of t3 / t4 was set to 0.2 to 0.8. When t3 / t4 exceeded 0.8, the cross-sectional area of the coating layer occupying the entire electrode wire 6 increased, and the high-temperature strength of the electrode wire 6 was increased. This is because the electrical conductivity is lowered and the electric discharge machining speed cannot be sufficiently improved and the machining accuracy cannot be improved. On the other hand, if it is less than 0.2, Zn in the coating layer on one side is consumed instantly during electric discharge machining, leading to a decrease in the cooling effect of the core material 1, and a sufficient improvement in electric discharge machining speed can be expected. This is because it disappears.

  The ratio between the layer thicknesses t1 and t2 of the reaction layers 4 and 5 and the length a of the long side of the entire electrode wire 6 was 0.002 to 0.005, respectively. This is because the layers 2 and 3 constituting the coating layer are not sufficiently adhered, and the tensile strength of the electrode wire 6 itself is reduced. Further, if it exceeds 0.005 (if the diffusion is excessive), the brittle reaction layers 4 and 5 are broken at the portion of the brittle reaction layers 4 and 5 and are not uniformly deformed. This is because the tensile strength of the electrode wire 6 itself is reduced.

  On the other hand, the covered electrode wire for wire electric discharge machining according to the present embodiment is manufactured as follows.

  First, a pure Zn layer 2 and an alloy layer 3 are provided around the core material 1 having a quadrangular cross section in order to form a coating layer, and then various heat treatments (diffusion treatment) and surface heat treatment are performed, whereby the core material 1 and the pure Zn material are treated. At the interface with the layer 2 and at the interface between the pure Zn layer 2 and the alloy layer 3, atoms are mutually diffused and rearranged. As a result, reaction layers 4 and 5 are formed at each interface between the core material 1 and the pure Zn layer 2 and between the pure Zn layer 2 and the alloy layer 3, and the coated electrode wire 6 for wire electric discharge machining is obtained.

  As the heat treatment method, a special short-time heat treatment method, for example, a surface plasma heat treatment technique is required. Specifically, only a hard copper alloy having a high Zn concentration can be heat-treated so that the wire drawing can be performed, and the core material 1 having a soft low Zn concentration is not heat-treated, and Zn evaporation can be prevented. Possible short-time heat treatment techniques (for example, plasma heat treatment and energized annealing) are necessary. The plasma heat treatment (also referred to as ion bombardment heat treatment) referred to here is a surface heat treatment utilizing glow discharge that occurs between a treatment object serving as a cathode and an anode in a reduced pressure atmosphere such as ion carburization or ion nitriding.

  Further, as the core material 1 on which the coating layer is formed travels in the lateral direction (horizontal direction) and the surface thereof is heat-treated using a plasma heat treatment technique, the pure Zn layer 2 having a low melting temperature in the middle of the coating layer. Is melted in a short time, the central core material 1 sinks down slightly due to the action of gravity, and the core material 1 is eccentric to the side where the electrode wires are present as shown in FIG. An electrode wire 6 having a non-uniform coating layer is obtained.

  Finally, the electrode wire 6 is passed through a wire drawing die, and the electrode wire 6 is appropriately reduced in diameter (cold wire drawing) to form a desired size, thereby obtaining a final product. In the diameter reduction processing, the electrode wire 6 may be repeatedly subjected to wire drawing die processing and heat treatment until a desired size is obtained.

  In the covered electrode wire 6 for wire electric discharge machining according to the present embodiment, in order to improve conductivity, the cross-sectional shape of the electrode wire is changed from a circular shape to a quadrangular shape to increase the current-carrying area of the electrode wire. As a result, the electrical conductivity is improved and the resistance becomes lower. As a result, when electric discharge machining is performed at a high temperature, the heat generated compared to the conventional electrode wire is reduced, the temperature is lowered, and the thermal burden on the electrode wire itself is reduced. The Therefore, the tension load to be applied can be further increased in order to further increase the processing accuracy.

  Further, as shown in FIG. 2A, since the conventional electrode wire 21 has a circular cross section, the portion where the discharge 22 is generated is only the portion where the electrode wire 21 and the work piece 23 are closest to each other. 22 is a point discharge. Since the conventional electrode wire 21 has few discharge spots by point discharge, it is somewhat in terms of further increasing the electric discharge machining speed and the stability of the discharge (generating the discharge 22 at a predetermined position of the workpiece 23). There was a difficulty. On the other hand, as shown in FIG. 2 (b), the coated electrode wire 6 for wire electric discharge machining according to the present embodiment has a quadrangular cross section, and therefore, the three side surfaces of the electrode wire 6 facing the workpiece 23. A discharge 22 occurs, and the discharge 22 is a surface discharge. Since the coated electrode wire 6 for wire electric discharge machining has many discharge portions due to surface discharge, the electric discharge machining speed can be further increased and the discharge stability is further enhanced. Since the outer peripheral corner portion of the electrode wire 6 is a circular corner portion R, the discharge 22 does not concentrate at the outer peripheral corner portion of the electrode wire 6, and surface discharge is possible. The chamfer radius of the circular corner portion R is appropriately adjusted according to the size of the electrode wire 6 within a range where the discharge 22 does not concentrate.

  Moreover, since the coated electrode wire 6 for wire electric discharge machining has 100% high-concentration Zn (pure Zn layer 2) on the inner layer side of the coating layer, it has excellent electric discharge performance, while a large amount with the progress of electric discharge machining. By evaporating Zn, the cooling effect of the electrode wire 6 is improved by the heat of vaporization during the evaporation, and the burden of heat applied to the electrode wire 6 can be further reduced. As a result, even if the electric discharge machining current is increased, the temperature rise can be suppressed lower than that of the general electrode wire, and the breakage limit of the electrode wire 6 is improved, so that the electric discharge machining speed and machining accuracy can be improved.

  In addition, when electric discharge machining is performed, one side of the electrode wire 6 (side surface of the electrode wire 6 on the side where the core material 1 is eccentric) is not discharged, so that it is not necessary to cover the one side with a coating layer having low tensile strength. The coating layer on one side can be made thinner. However, in order to improve the high-temperature cooling effect of the core material 1, a coating layer having an appropriate high Zn concentration is required, so that the thickness is appropriate on the remaining three side surfaces of the electrode wire 6, particularly on the surface opposite to a certain side surface. By covering with the coating layer, the conductivity that contributes to the high temperature strength of the electrode wire 6 can be improved, and the processing speed can be greatly increased.

  Further, by providing reaction layers 4 and 5 at the interface between the core material 1 and the pure Zn layer 2 and at the interface between the pure Zn layer 2 and the alloy layer 3, respectively, between the layers 2 and 3 constituting the core material 1 and the coating layer. The adhesiveness of is improved. As a result, the coated electrode wire 6 for wire electric discharge machining with improved tensile strength and good electric discharge machining performance can be obtained.

  According to the electrode wire 6 according to the present embodiment, the core material 1 having good conductivity is used, and the pure Zn layer 2 is provided around the core material 1, whereby the electric discharge machining performance is further improved. Further, when the pure Zn layer 2 is exposed due to the consumption of the Cu-Zn alloy layer 3 and the reaction layer 5 on the outer layer side during the electric discharge machining, the pure Zn layer 2 is discharged, so that the discharge characteristics are good and the excellent machining accuracy is achieved. Is obtained. At this time, the pure Zn layer 2 is covered with the Cu—Zn alloy layer 3 and the reaction layer 5, and is thicker than the Cu—Zn alloy layer 3, and has a sufficient layer thickness. The pure Zn layer 2 does not instantly evaporate during electric discharge machining as in the case of conventional electrode wires.

  In addition, the pure Zn layer 2 gradually evaporates with the progress of electric discharge machining, but the cooling effect of the electrode wire 6, particularly the core material 1 is improved by the heat of vaporization during the evaporation. For this reason, even if the electrical discharge machining current is increased in order to increase the electrical discharge machining speed, the temperature rise of the electrode wire 6 can be suppressed lower than that of a general brass wire, and the thermal burden on the electrode wire 6 itself is reduced. As a result, since the disconnection limit of the electrode wire 6 itself is improved, the electric discharge machining speed can be improved. In addition, since the electrode wire 6 according to the present embodiment having a quadrangular cross section has a wider discharge range than the conventional electrode wire having a circular cross section, the electric discharge machining speed can be improved.

  As mentioned above, it cannot be overemphasized that embodiment of this invention is not limited to embodiment mentioned above, and various things are assumed in addition.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

Example 1
A pure Zn layer having a thickness of 0.25 mm and a thickness of 0.125 mm are sequentially formed around a core material made of Cu-0.16 wt% Zr with long and short sides of 2.5 mm and 2.0 mm. A Cu-35 wt% Zn alloy layer is formed.

  Next, the coated wire is subjected to wire drawing and heat treatment, and the rectangular wire electric discharge machining electrode wires of size a and b having an inner reaction layer of layer thickness t1 and an outer reaction layer of layer thickness t2 in order on the outer periphery of the core material. Was made. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.23, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer is 0.002 to 0.005, which is thinner than the three-side coating layer t4, and the ratio t3 / t4 is 0.5.

(Example 2)
A pure Zn layer having a thickness of 0.20 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.125 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.20, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer is 0.002 to 0.005, which is thinner than the three-side coating layer t4, and the ratio t3 / t4 is 0.5.

(Comparative Example 1)
A pure Zn layer having a thickness of 0.40 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.125 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.295, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer is 0.002 to 0.005, which is thinner than the three-side coating layer t4, and the ratio t3 / t4 is 0.5.

(Comparative Example 2)
A pure Zn layer having a thickness of 0.04 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.02 mm are sequentially formed around the same core material as in Example 1. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode wire is 0.045, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode wire is The thickness t3 of the one-side coating layer was 0.002 to 0.005, thinner than the three-side coating layer t4, and the ratio t3 / t4 was 0.5.

(Comparative Example 3)
A pure Zn layer having a thickness of 0.20 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.02 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.20, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer was 0.001 to 0.002, thinner than the three-side coating layer t4, and the ratio t3 / t4 was 0.5.

(Comparative Example 4)
A pure Zn layer having a thickness of 0.20 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.02 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.20, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer is 0.005 to 0.006, which is thinner than the three-side coating layer t4, and the ratio t3 / t4 is 0.5.

(Comparative Example 5)
A pure Zn layer having a thickness of 0.20 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.125 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode line is 0.20, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode line is The thickness t3 of the one-side coating layer is 0.002 to 0.005, which is thinner than the three-side coating layer t4, and the ratio t3 / t4 is 0.2.

(Comparative Example 6)
A pure Zn layer having a thickness of 0.20 mm and a Cu-35 wt% Zn alloy layer having a thickness of 0.125 mm are sequentially formed around the same core material as in the first embodiment. Thereafter, an electrode wire for wire electric discharge machining was produced in the same manner as in Example 1. Here, the ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode wire is 0.20, and the ratio of the layer thickness t1, t2 of the reaction layer to the length of the long side of the entire electrode wire is The thickness t3 of the one-side coating layer was 0.002 to 0.005, thinner than the three-side coating layer t4, and the ratio t3 / t4 was 0.9.

(Conventional example 1)
A wire electric discharge machining electrode wire having an outer diameter of φ0.35 mm made of a simple Cu-35 wt% Zn alloy was produced.

  The core material composition (wt%) of each electrode wire in Examples 1 and 2, Comparative Examples 1 to 6, and Conventional Example 1, the composition of Cu—Zn alloy layer (wt%), each layer thickness / a, machining accuracy, and electrical discharge machining Table 1 shows the electric discharge machining speed during the test.

  Here, the processing accuracy is a relative accuracy when the processing accuracy of the electrode wire of Conventional Example 1 is 1.0. The electric discharge machining speed is a relative speed when the electric discharge machining speed of the electrode wire of Conventional Example 1 is 1.00.

  As shown in Table 1, each of the electrode wires of Examples 1 and 2 has a processing accuracy as high as 3.0 or more, which is significantly improved as compared with Conventional Example 1. In addition, the electric discharge machining speeds were 2.5 and 2.4, respectively, 2.0 or more, and the electric discharge machining speed was improved by about 140 to 150% as compared with Conventional Example 1.

  On the other hand, since the value of the thickness / a of the coating layer of the electrode wire of Comparative Example 1 is 0.295 which is larger than the limited range (0.05 to 0.25), the electric discharge machining speed is sufficiently high. Could not improve. Moreover, since the electrode thickness of Comparative Example 2 is 0.045 where the layer thickness / a of the coating layer is smaller than the limited range (0.05 to 0.25), only an electric discharge machining speed of 1.6 is obtained. The electric discharge machining speed could not be sufficiently improved. Moreover, since the discharge performance was not good, the processing accuracy was as low as 1.5.

  In the electrode wires of Comparative Examples 3 and 4, since the layer thickness / a value of the reaction layer does not satisfy the limited range (0.002 to 0.005), the drawability is not good and the electrode wires can be produced. It was impossible. Therefore, a high temperature tensile test and an electric discharge machining test could not be performed.

  In the electrode wires of Comparative Examples 5 and 6, since the value of the thickness t3 / t4 of the coating layer does not satisfy the limited range (0.2 to 0.8), the electric discharge machining speed and machining accuracy are sufficiently improved. I couldn't.

It is a cross-sectional view of a coated electrode wire for wire electric discharge machining according to a preferred embodiment of the present invention. It is a cross-sectional view which shows the electric discharge machining state at the time of electric discharge machining of the conventional electrode and the coated electrode wire for wire electric discharge machining according to the present embodiment. 2A shows a conventional coated electrode wire for wire electrical discharge machining, and FIG. 2B shows a coated electrode wire for wire electrical discharge machining according to the present embodiment. It is a figure which shows Zn concentration distribution of each reaction layer in FIG. 3A shows the reaction layer on the inner layer side, and FIG. 3B shows the reaction layer on the outer layer side.

Explanation of symbols

1 Core material 2 Pure Zn layer (coating layer)
3 Alloy layer (coating layer)
4,5 reaction layer (coating layer)
6 Coated electrode wire for wire EDM R Round corner

Claims (13)

  A covered electrode wire for wire electric discharge machining, having a coating electrode wire for wire electric discharge machining having two or more coating layers on an outer periphery of a core material, and having an R-shaped circular corner at an outer peripheral corner portion.   The coated electrode wire for wire electric discharge machining according to claim 1, wherein the core material is eccentrically arranged on a side surface having the electrode wire, and three side surfaces excluding the side surface on the eccentric side are used as an electric discharge machining surface.   The coating layer has a pure Zn layer on the inner layer side and an alloy layer on the outer layer side, and a Cu-Zn intermetallic compound reaction layer is formed at the interface between the core material and the pure Zn layer and at the interface between the pure Zn layer and the alloy layer. The covered electrode wire for wire electric discharge machining according to claim 1 or 2, respectively.   The ratio of the layer thickness of the coating layer to the length a of the long side of the entire electrode wire is 0.05 to 0.25, the layer thicknesses t1 and t2 of the reaction layers and the length a of the long side of the entire electrode wire The coated electrode wire for wire electric discharge machining according to any one of claims 1 to 3, wherein the ratio of the electrode wire is 0.002 to 0.005.   The thickness t3 of the coating layer on the side where the core material is eccentric is thinner than the thickness t4 of the coating layer on the opposite side, and the ratio of t3 / t4 is 0.2 to 0.8. A coated electrode wire for wire electric discharge machining as described in 1.   Each of the reaction layers is a layer in which the Zn concentration is inclined, and the reaction layer at the interface between the core material and the pure Zn layer has a Zn concentration that continuously increases from the inside toward the outside. The coated electrode wire for wire electric discharge machining according to any one of claims 1 to 5, wherein the reaction layer at the interface of the alloy layer has a Zn concentration that decreases continuously from the inside toward the outside.   The coated electrode wire for wire electric discharge machining according to any one of claims 1 to 6, wherein the coating layer has a pure Zn layer on the inner layer side and an alloy layer having a composition of Cu-30 to 46 wt% Zn on the outer layer side.   The coated electrode wire for wire electric discharge machining according to any one of claims 3 to 7, wherein each of the reaction layers is composed of an intermetallic compound having a composition of Cu-60 to 90 wt% Zn. The heartwood is
Pure Cu,
Cu-0.02-0.2 wt% Zr alloy,
Cu-0.15-0.70 wt% In alloy,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy,
Cu-0.15-0.70 wt% Sn alloy,
Cu-5-30 wt% Zn alloy,
Cu-0.2-20 wt% Ag alloy,
An alloy obtained by adding at least one of Zr, Cr, Mg, Al, Si, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Or an Fe-based alloy,
The coated electrode wire for wire electric discharge machining according to any one of claims 1 to 8, which is constituted by:   In the method of manufacturing a coated electrode wire for wire electric discharge machining having two or more coating layers on the outer periphery of the core material, the coating layer is formed on the outer periphery of the core material having a square cross section, and then subjected to diffusion treatment and surface treatment by heat treatment. Manufacturing of a coated electrode wire for wire electric discharge machining, wherein a reaction layer is formed at each interface by diffusing atoms at the interface between the core material and the coating layer and at the interface between the coating layers and rearranging the atoms. Method.   The wire electric discharge machining according to claim 10, wherein a pure Zn layer is first provided on an outer periphery of the core material, an alloy layer having a composition of Cu-30 to 46 wt% Zn is provided around the pure Zn layer, and then the heat treatment is performed. For producing a coated electrode wire for use.   A surface plasma heat treatment is performed on the core material coated with the coating layer in order to perform a good wire drawing process, and only the high-zinc alloy layer having a hard surface is heat-treated, and the soft core material in the core is not heat-treated. The manufacturing method of the covered electrode wire for wire electric discharge machining of 10 or 11.   The core material coated with the above coating layer is run in the lateral direction, and a pure Zn layer having a low intermediate melting temperature is melted in a short time by plasma heat treatment technology, and the central core material is submerged by the action of gravity. The method for producing a coated electrode wire for wire electric discharge machining according to any one of claims 10 to 12, wherein the core material is eccentric to a side surface where the electrode wire is present, and a coating layer having a non-uniform thickness is formed around the core material.

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