JP5647410B2 - Electrode wire for electric discharge machining - Google Patents

Description

  The present invention generally relates to an electrode wire for electric discharge machining, and more particularly, to an electrode wire for wire electric discharge machining made of a material containing tungsten.

  Conventionally, an electrode wire made of a material containing tungsten has been developed and used for wire electric discharge machining.

  For example, JP-A-2-109640 (hereinafter referred to as Patent Document 1) discloses Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Disclosed is an electrode wire for electric discharge machining comprising a tungsten alloy containing at least 0.0010 to 1.0% by weight of at least one selected from the group containing Lu and their respective oxides, the balance being tungsten. ing.

  Japanese Laid-Open Patent Publication No. 2-145214 (hereinafter referred to as Patent Document 2) discloses a tungsten alloy containing at least 0.001 to 1.0% by weight of Re and the balance being tungsten and inevitable impurities. An electric discharge machining electrode wire is disclosed.

Japanese Patent Laid-Open No. 2-109640 JP-A-2-145214

  Since electric discharge machining has a lower machining speed than other cutting techniques, it is required to increase the machining speed using an electric discharge machining electrode wire made of a conventional tungsten alloy in order to improve productivity. Yes. As one measure for the requirement, it is known to increase the tension of the electrode wire during electric discharge machining. When the tension of the electrode wire for electric discharge machining is increased, the machining speed can be increased.

  In Patent Document 1, an electrode wire for electric discharge machining made of a tungsten alloy containing Ce (cerium) or the like is disclosed. Cerium acts to improve the discharge performance of the electrode wire for electric discharge machining. However, if an electrode wire made of a tungsten alloy containing cerium is used and the tension of the electrode wire is made higher than a certain value during electric discharge machining, there is a problem that disconnection is likely to occur during electric discharge machining.

  Patent Document 2 discloses an electrode wire for electric discharge machining made of a tungsten alloy containing Re (rhenium). Since rhenium acts to increase the recrystallization temperature of the tungsten alloy, the high temperature strength of the tungsten alloy is improved. Accordingly, even when the electrode wire made of a tungsten alloy containing rhenium is used and the tension of the electrode wire is set higher than a certain value during electric discharge machining, disconnection hardly occurs during electric discharge machining. However, when an electrode wire made of a tungsten alloy containing rhenium is used, the electric discharge machining speed is inherently lower than when an electrode wire made of a tungsten alloy containing cerium is used. Even if the tension of the electrode wire is made higher than a certain value, the processing speed cannot be increased to the extent that it can contribute to productivity improvement.

  Accordingly, an object of the present invention is to provide an electric discharge that is less likely to cause disconnection even when the tension of the electrode wire is increased during electric discharge machining, and that can increase the machining speed as compared with conventional electric discharge machining using an electrode wire for electric discharge machining. It is to provide a processing electrode wire.

The electrode wire for electric discharge machining according to the present invention contains rhenium in an amount of 0.3 % by mass to 1 % by mass and cerium oxide in an amount of 0.3 % by mass to 1% by mass with the balance being tungsten and inevitable impurities. Including.

The electrode wire for electric discharge machining of this invention preferably contains 0.5 % by mass or more and 1% by mass or less of cerium oxide .

  By using the electrode wire for electric discharge machining of the present invention, it is possible to make disconnection less likely to occur even if the tension of the electrode wire is increased during electric discharge machining, and to process more than electric discharge machining using a conventional electrode wire for electric discharge machining. It becomes possible to increase the speed.

It is a figure which shows the relationship between the tension | tensile_strength applied to an electrode wire during electrical discharge machining, and the machining speed about the conventional electrical discharge machining electrode wire and the electrical discharge machining electrode wire of this invention.

  In general, in wire electric discharge machining, the electrode wire receives a repulsive force due to electric discharge, and is easily deflected in the direction opposite to the traveling direction of the electrode wire, so that the distance between the electrode wire and the workpiece is increased. As a result, the processing speed decreases.

Therefore, in the electrode wire for electric discharge machining of the present invention, rhenium (Re) is 0.1 mass% or more and 2 mass% or less, lanthanum oxide (La ₂ O ₃ ), cerium oxide (CeO ₂ ), and yttrium oxide (Y ₂ O). ₃ ) at least one metal oxide selected from the group consisting of 0.1 to 1% by mass, and the balance contains tungsten and inevitable impurities.

  When an electrode wire made of a material having the above composition is used, it is considered that the deflection in the direction opposite to the traveling direction of the electrode wire can be greatly reduced by increasing the tension of the electrode wire during electric discharge machining. Thereby, a processing speed can be improved.

  Further, when an electrode wire made of a material having the above composition is used, disconnection does not occur even if the tension of the electrode wire is increased during electric discharge machining.

  From these facts, rhenium and lanthanum oxide, cerium oxide and / or yttrium oxide coexist in tungsten within the above-mentioned limited range, respectively, thereby increasing the tension of the electrode wire during electric discharge machining. In addition to the action of making wire breakage difficult, it also works to increase the processing speed further than the electric discharge machining using the conventional electric discharge machining electrode wire made of a tungsten alloy containing only rhenium or a tungsten alloy containing cerium or the like. It is considered a thing.

  When the content of lanthanum oxide, cerium oxide and / or yttrium oxide is less than 0.1% by mass, there is a problem that the discharge property is deteriorated and the processing speed is lowered. When the content of lanthanum oxide, cerium oxide and / or yttrium oxide exceeds 1% by mass, the material becomes brittle, so that many cracks and breaks occur when the material is drawn to produce an electrode wire for electric discharge machining. As a result, there is a problem in that the manufacturing yield decreases.

  When the rhenium content is less than 0.1% by mass, even if the tension of the electrode wire is increased during electric discharge machining, the deflection in the direction opposite to the traveling direction of the electrode wire is increased during electric discharge machining. The effect of improvement cannot be obtained. If the rhenium content exceeds 2.0 mass%, the material is easily work-hardened. Therefore, when the material is drawn to produce an electrode wire for electric discharge machining, cracks and disconnections frequently occur and the production yield increases. There is a problem that decreases.

  In order to further exert the above-described effects of the present invention, the electrode wire for electric discharge machining has a rhenium content of 0.3 mass% to 1.5 mass% and the metal oxide content of 0.3 mass%. The content is preferably 1% by mass or less.

  Moreover, the outer diameter of the electrode wire for electric discharge machining of the present invention is within the range of the outer diameter of a general electrode wire for electric discharge machining. Specifically, when the outer diameter of the electric discharge machining electrode wire of the present invention is in the range of 0.005 mm or more and 0.25 mm or less, the effects of the present invention can be effectively exhibited.

  As described below, a tungsten alloy wire was produced as an electrode wire for electric discharge machining used in Examples 1 and 2.

(Preparation of raw materials)
A commercially available tungsten (W) powder having a purity of 99.99% or more and an average particle size of 2.5 μm, a commercially available rhenium (Re) powder having a purity of 99.99% or more and an average particle size of 6.2 μm, A commercially available cerium oxide (CeO ₂ ) powder having a purity of 99.99% or more and an average particle diameter of 3.5 μm was prepared.

  In addition, when the purity of each powder is lower than said purity, there exists a possibility that the wire finally obtained by an impurity producing | generating a compound with tungsten may become embrittled. The tungsten powder preferably has an average particle size of 1 to 4 μm, the rhenium powder has an average particle size of 1 to 20 μm, and the cerium oxide powder has an average particle size of 0.5 to 10 μm. If the average particle size of each powder exceeds the above upper limit, voids are likely to occur in the molded body, and the density of the molded body is reduced, so that there is a possibility that the finally obtained wire will be cracked or chipped. is there. Moreover, the powder manufacturing cost increases that the average particle diameter of each powder is less than the above lower limit.

(Mixing process)
The raw material powder prepared above was mixed for 3 hours using a V-type mixer at the composition ratio of each sample shown in Examples 1 and 2 below.

  In addition, 0.001 mass% or more and 0.1 mass% or less of 1 or more types selected from the group containing aluminum (Al), silicon (Si), potassium (K) and their respective oxides are added and mixed May be.

(Molding process)
The mixed powder obtained above was compression molded at a pressure of 350 MPa using a mold press. Thereby, a square rod-shaped powder compact having a size of 15 mm × 15 mm × 1000 mm was produced.

  In addition, it is preferable that said pressure exists in the range of 250-450 MPa. If the pressure is less than 250 MPa, a molded body cannot be obtained, or even if a molded body can be obtained, the molded body may be damaged in handling or subsequent processes. Even when the pressure exceeds 450 MPa, a more preferable effect cannot be obtained in producing a molded body.

(Preliminary sintering process)
The powder compact obtained above was held in a hydrogen gas atmosphere at a temperature of 1250 ° C. for 30 minutes to prepare a temporary sintered body.

  In addition, the atmosphere in said temporary sintering process should just be a non-oxidizing atmosphere other than hydrogen gas atmosphere, for example, a vacuum atmosphere, argon gas atmosphere, etc. may be sufficient as it. The temperature in the preliminary sintering step is preferably in the range of 1000 to 1500 ° C., and the holding time is preferably in the range of 20 minutes to 5 hours. If the temperature and holding time exceed the above upper limit values, even if pre-sintering is performed, a more preferable effect cannot be obtained, and a disadvantage that costs increase is caused. If the temperature or holding time is less than the above lower limit value, the effect obtained by pre-sintering is small, and the pre-sintered body may be damaged in handling or subsequent processes.

(Sintering process)
The preliminary sintered body obtained above was held in a hydrogen gas atmosphere at a temperature of 2800 ° C. for 15 minutes to produce a sintered body.

  The atmosphere in the above sintering step may be a non-oxidizing atmosphere other than a hydrogen gas atmosphere, and may be a vacuum atmosphere, an argon gas atmosphere, or the like, for example. The temperature in the preliminary sintering step is preferably in the range of 1900 to 3000 ° C., and the holding time is preferably in the range of 5 to 90 minutes. If the temperature or holding time exceeds the above upper limit value, cerium oxide may cause grain boundary migration, and the dispersion of cerium oxide may become non-uniform. If the temperature or holding time is less than the above lower limit, sintering may be insufficient.

(Drawing process)
The sintered body obtained above was rolled and annealed for drawing. A tungsten alloy wire having an outer diameter of 0.03 mm was produced by performing an electrolytic treatment for removing oxides present on the surface of the obtained wire.

[Example 1]
By the manufacturing method described above, as a conventional electrode wire for electric discharge machining, a tungsten alloy wire containing 0.5% by mass of rhenium (Re), a tungsten alloy wire containing 0.5% by mass of cerium oxide (CeO ₂ ), A tungsten alloy wire containing 0.5% by mass of rhenium and 0.5% by mass of cerium oxide was produced as an electrode wire for electric discharge machining.

  Using the obtained tungsten alloy wire as an electrode wire for wire electric discharge machining, electric discharge machining was performed under the following conditions. During electric discharge machining, tensions of 0.60N, 0.70N, 0.85N, and 1.05N were applied to the electrode wires.

(Processing conditions)
(1) Used processing machine: FS-150W manufactured by SODIK 1989 (2) Work material: High speed steel SKH57 (JIS G 4403)
(3) Workpiece thickness: 5.7 mm
(4) Cutting work material: straight line processing, cutting length 20mm
(5) Electrode wire: outer diameter 0.03 mm, length 3000 m
(6) Electrical discharge machining conditions

  As a result obtained by the above electric discharge machining, FIG. 1 shows the relationship between the tension applied to the electrode wire during electric discharge machining and the machining speed for the conventional electric discharge machining electrode wire and the electric discharge machining electrode wire of the present invention. . In addition, the machining speed of electric discharge machining was calculated by measuring the time required to cut the workpiece by a length of 20 mm.

As shown in FIG. 1, 0.5 mass of cerium oxide (CeO ₂ ) is used as a conventional electrode wire for electric discharge machining as compared with the case where a tungsten alloy wire containing 0.5 mass% of rhenium (Re) is used. It can be seen that when a tungsten alloy wire containing% is used, the value of the electric discharge machining speed is high regardless of the tension applied to the electrode wire. Furthermore, when a tungsten alloy wire containing 0.5% by mass of rhenium and 0.5% by mass of cerium oxide is used as the electrode wire for electric discharge machining of the present invention, rhenium is used as the electrode wire for conventional electric discharge machining. Compared to the case of using a tungsten alloy wire containing 0.5% by mass or a tungsten alloy wire containing 0.5% by mass of cerium oxide, the value of the machining speed of electric discharge machining is whatever the tension applied to the electrode wire. It can be seen that the machining speed of electric discharge machining can be increased as the tension value is increased as well as the increase in tension.

[Example 2]
According to the manufacturing method described above, the composition shown in Table 2 below is cerium oxide (CeO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), and rhenium (Re) as the electrode wire for electric discharge machining. Tungsten alloy wires (sample numbers 1 to 22) included in [mass%] were produced. In Table 2, samples marked with an asterisk (*) indicate that the composition is outside the scope of the present invention (Comparative Example), and those without a mark indicate that the composition is within the scope of the present invention (present invention). Example).

  Using the obtained tungsten alloy wire as an electrode wire for wire electric discharge machining, electric discharge machining was performed under the same conditions as in Example 1. During the electric discharge machining, a tension of 1.05 N was applied to the electrode wire. The cutting process of the workpiece was a linear process, and the cutting length was 200 mm.

  As a result obtained by the above-described electric discharge machining, the electric discharge machining speed was measured in the same manner as in Example 1 for the electric discharge machining electrode wires of the present invention and the comparative example. In addition, the number of electrode wire breaks that occurred during the electric discharge machining was measured. Table 2 shows the average processing speed and the number of disconnections measured for each sample number. Furthermore, the manufacturing yield at the time of the wire drawing process of the tungsten alloy having the composition of each sample number was calculated. As the value of the production yield, the ratio of the weight of the non-defective product of the wire obtained after the wire drawing step to the weight of the sintered body before the wire drawing step was calculated. Table 2 shows the calculated production yield values during wire drawing. In Table 2, in order to compare the measurement data between the inventive example and the comparative example, the composition and measurement data are shown redundantly for the sample numbers 1, 6, and 7.

  As shown in Table 2, when electric discharge machining was performed using an electrode wire made of a tungsten alloy containing only rhenium (sample numbers 1, 13, and 15), no breakage occurred during electric discharge machining. It can be seen that the speed is considerably lower than the inventive example. When electric discharge machining is performed using an electrode wire made of a tungsten alloy containing cerium oxide (sample numbers 3, 5, 7, and 9), electric discharge machining is carried out using an electrode wire made of a tungsten alloy containing only rhenium. It can be seen that the wire breakage occurred many times during the electric discharge machining, although the machining speed was higher than that in the case of performing (Sample Nos. 1, 13, 15).

  On the other hand, when the electric discharge machining is performed using the electrode wire of the present invention example, not only the machining speed is higher than the comparative example, but also the number of disconnections generated during the electric discharge machining is small, or It turns out that it was 0.

  In addition, the tungsten alloy (sample number 10) whose content of cerium oxide exceeds the upper limit outside the scope of the present invention, or the tungsten alloy (sample number) whose content of rhenium exceeds the upper limit outside the scope of the present invention. 18) When the electrical discharge machining was performed using the electrode wire of the comparative example consisting of 18), the machining speed was the same as that of the present invention example, and no disconnection occurred during the electrical discharge machining, but the production yield during wire drawing was It can be seen that it is considerably lower than the inventive example. In addition, when electric discharge machining is performed using the electrode wire of the present invention example made of a tungsten alloy (sample numbers 17 and 22) whose rhenium content is the upper limit of the range of the present invention, another example of the present invention Although the cutting speed was the same and no breakage occurred during the electric discharge machining, it can be seen that the production yield at the time of wire drawing is slightly lower than the other examples of the present invention.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

  The electrode wire for electric discharge machining according to the present invention can prevent breakage even if the tension of the electrode wire is increased during electric discharge machining, and increases the machining speed as compared with electric discharge machining using a conventional electrode wire for electric discharge machining. Therefore, it can be used for industrial cutting of various materials.

Claims (2)

An electrode wire for electric discharge machining comprising rhenium in an amount of 0.3 % by mass to 1 % by mass and cerium oxide in an amount of 0.3 % by mass to 1% by mass with the balance containing tungsten and inevitable impurities. The electrode wire for electric discharge machining according to claim 1, comprising 0.5 % by mass or more and 1% by mass or less of cerium oxide .

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