Electrode wire for electrical discharge machining

Abstract

The present invention relates to an electrode wire for electrical discharge machining, preferably comprising: a core wire formed of a first metal, and an alloy layer formed on the outer periphery of the core wire by mutual diffusion of a second metal plated on the outer surface of the core wire; the alloy layer includes: a part composed of an α phase + β' phase, and crystal grains of the β' phase; cracks are formed on the surface of the alloy layer. With the above structure, it is possible to provide an electrode wire for electrical discharge machining in which the machining speed and surface roughness of the workpiece are improved, fine debris of the electrode wire rarely occurs, and the surface is uniform.

Description

Technical Field

[0001] The present invention relates to an electrode wire for electrical discharge machining. Specifically, it is an electrode wire for electrical discharge machining that forms grains of β' phase with cracks on the surface of the electrode wire, minimizes the generation of fine debris of the electrode wire, improves the efficiency and machining speed of electrical discharge, and improves machining precision and surface roughness. Background Art

[0002] Wire electrical discharge machining is a method used in the past, in which electrical discharge is carried out between a workpiece and an electrode wire for wire electrical discharge machining with a machining fluid such as water as a medium, the electrode wire and the workpiece are relatively moved, and the workpiece is cut into a desired shape.

[0003] In this electrical discharge machining method, various electrode wires such as high-strength electrode wires containing components such as molybdenum and tungsten like pure copper electrode wires and brass electrode wires are used as the electrode wire.

[0004] As such an electrode wire, USP 4,686,153 is a prior art well-known for galvanizing a copper-clad steel wire with a diameter of 0.49 mm, then performing wire drawing processing with a diameter of 0.2 mm on the galvanized copper-clad steel wire, and heating it at a temperature of about 300 °C for one hour in a non-oxidizing nitrogen atmosphere to diffuse copper into the zinc layer and convert the zinc layer into a copper-zinc alloy layer. The above copper-zinc alloy has a zinc concentration of about 45%, and the concentration gradually decreases on the surface. The average zinc concentration of the copper-zinc alloy layer is less than 50% and reaches more than 10%. The zinc concentration of the β-phase copper-zinc alloy reaches 40% - 50%, and the surface layer includes a copper-zinc alloy layer of the β-phase on the outer peripheral surface. However, the above technology is to improve the machining speed on the premise that the surface degree obtained in the cutting process is not deteriorated.

[0005] Therefore, the inventors of the present invention proposed Korean Patent Registration No. 10-518727 for a porous electrode wire for electrical discharge machining and Korean Patent Registration No. 10-518731 for a method for manufacturing a porous electrode wire for electrical discharge machining.

[0006] According to the above technology, the copper-containing core wire metal and the galvanized layer form an alloy coating composed of γ-phase grain blocks on the outer periphery of the core wire metal through mutual diffusion reaction, form cracks on the surface of the electrode wire, further improve the cooling effect of the electrode wire, and thus obtain a significant improvement compared with the electrode wire proposed in USP 4686,153.

[0007] However, regarding the above technology, as a result of research on the alloy coating of the γ-phase formed on the brass core wire, the inventors of the present invention consulted the Korea Institute of Materials Science. Regarding the Brinell hardness of "HYPER Zn" with a zinc content of 50 weight percent in the binary alloy of copper (Cu)-zinc (Zn), according to the phase diagram of the binary alloy phase change of copper (Cu)-zinc (Zn) and the comparison diagram of hardness as Figure 2 shown for confirmation.

[0008] According to the above Figure 2 it can be confirmed that the alloy coating of the γ-phase is actually as Figure 2 shown, with a Brinell hardness of 350 HB or more, which is very high, and the brittleness is also very high. The alloy coating of the γ-phase with the above properties is likely to break under the drawing pressure during the drawing process, generating cracked fragments, and a large number of fine debris adheres inside and outside the cracks. During electrical discharge machining, due to the secondary discharge of the cracked fragments and fine debris, it becomes an obstacle to the improvement of the machining speed.

[0009] Therefore, the present inventors have re-proposed Korean Patent Registration No. 10-1284495, a porous electrode wire for electrical discharge machining and its manufacturing method.

[0010] The above technology is that, compared with the electrode wires proposed in Korean Registered Patent Nos. 10-518727 or 10-518731, during the process of winding wire on the surface of the electrode wire for electrical discharge machining, the material forming the core wire drills through the grains (mainly forming the α-phase and β-phase) of the cracks formed on the second alloy layer, surrounding the cracked second alloy layer (mainly formed by the γ-phase) with relatively soft grains, reducing the fine debris generated by the fragmentation of the second alloy layer during the electrical discharge process, and further improving the electrical discharge machining speed and the surface roughness of the workpiece.

[0011] However, the above technology can improve the machining speed of the workpiece and the surface roughness of the workpiece to a certain extent, but it is still not sufficient to effectively reduce the fine debris of the electrode wire generated by the partial cracking of the cracks (mainly the second alloy layer).

[0012] In addition, in the electrode wire for electrical discharge machining and its manufacturing method of USP 5,945,010, similar to the above patent, as a patent citing the concept of cracks on the on-line electrode wire, in order to manufacture the electrode wire, zinc with a vaporization temperature lower than that of the core wire is first electroplated on the core wire. In order to generate a sufficient diffusion reaction between the electroplated zinc coating and the core wire, a diffusion heat treatment process is carried out within the range of 150 °C to 400 °C for 1 to 4 hours until the zinc coating forms an alloy layer of the γ-phase. Then, according to the result of the diffusion heat treatment, as Figure 3An electrode wire in which grain blocks 9 of a γ-phase are formed on the surface. The symbol tf not shown is the maximum thickness of the γ-phase brass alloy coating.

[0013] However, the advantages of the above technology are also to improve the processing speed by forming an electrode wire with an alloy coating composed of grain blocks 9 of an alloy of zinc and copper, i.e., the γ-phase, on the surface of the electrode wire. However, the alloy coating that forms cracks on the brass core wire 8 is as Figure 1 and Figure 2 shown, mainly formed of the γ-phase, so it is prone to cracking due to being unable to withstand the drawing pressure during the drawing process, generating a large number of cracked fragments and fine debris, and thus unable to effectively improve the processing speed and surface roughness. SUMMARY OF THE INVENTION

[0014] TECHNICAL PROBLEM

[0015] The present invention is proposed to solve the above problems, and its purpose is to provide an electrode wire for electrical discharge machining that can minimize the generation of fine debris of the electrode wire, improve the discharge efficiency and processing speed, and at the same time improve the processing precision and surface roughness.

[0016] Another object of the present invention is to provide an electrode wire for electrical discharge machining, which mainly forms grains, cracks and pinholes of the β'-phase on the outermost layer of the electrode wire, and forms a fine space composed of a cave-like ε-phase and a γ-phase + ε-phase deeper than the crack on the surface of the electrode wire in the direction of the core wire, so that the cooling water provided by high pressure can penetrate into the core wire, thereby maximizing the cooling effect and not generating fine debris.

[0017] Another object of the present invention is to provide an electrode wire for electrical discharge machining that forms grains and cracks of the β'-phase on the surface of the electrode wire and is more uniform than the γ-phase cracks compared with the current electrode wire that forms γ-phase grains on the surface of the electrode wire.

[0018] Another object of the present invention is to provide an electrode wire for electrical discharge machining that coats a conductive polymer on the surface of the electrode wire to improve the conductivity of the electrode wire surface, thereby further improving the processing speed.

[0019] Another object of the present invention is to provide an electrode wire for electrical discharge machining that coats a polymer of a semiconductor or insulator on the surface of the electrode wire, or forms an oxide layer with semiconductor or insulating properties, to make the irregular discharge current uniform, reduce the generation of micro-cracks on the surface of the workpiece, etc., so as to improve the surface roughness and precision.

[0020] TECHNICAL SOLUTION

[0021] To achieve the above object, the electrode wire for electrical discharge machining of the present invention preferably includes: a core wire formed of a first metal; an alloy layer formed on the outer peripheral surface of the core wire by mutual diffusion with the core wire, the alloy layer including: a portion composed of an α phase + a β' phase; grains of the β' phase formed on the outer periphery of the portion composed of the α phase + the β' phase; and cracks formed on the surface of the alloy layer.

[0022] Preferably, at least a part of the outer periphery of the portion composed of the α phase + the β' phase forms a recessed part, and the grains of the β' phase are formed by being embedded in the recessed part formed on the outer periphery of the portion composed of the α phase + the β' phase.

[0023] Preferably, the grains of the β' phase are formed by being embedded in a wedge shape on the outer periphery of the portion composed of the α phase + the β' phase.

[0024] Preferably, the grains of the β' phase are discontinuously formed on the outer periphery of the portion composed of the α phase + the β' phase.

[0025] Preferably, the alloy layer further includes grains of a β' phase + a γ phase.

[0026] Preferably, pin holes are also formed on the surface of the alloy layer.

[0027] Preferably, the surface layer of the pin holes is formed of at least one of a γ phase + an ε phase and an ε phase.

[0028] Preferably, fine spaces in the form of cavities that are deeper than the cracks are formed on the surface of the alloy layer in the direction of the core wire.

[0029] Preferably, the surface layer of the portion having the fine spaces in the form of cavities is formed of at least one of a γ phase + an ε phase and an ε phase.

[0030] Preferably, cracks are formed on the grains of the β' phase.

[0031] Preferably, at least a part of the core wire penetrates through the alloy layer and is exposed on the surface of the electrode wire.

[0032] Preferably, the surface of the above alloy layer is coated with at least one of an oxide layer, a conductive polymer, a semiconductor polymer, and an insulating polymer.

[0033] Preferably, the first metal is one of copper, brass, or a copper-containing metal, and the second metal is formed of any one of zinc, aluminum, tin, or their alloys.

[0034] Advantageous Effects

[0035] The beneficial effects of the present invention are as follows: It is possible to provide an electrode wire for electrical discharge machining that reduces the generation of fine debris in the electrode wire, improves the discharge efficiency and machining speed, and improves the machining precision and surface roughness;

[0036] It is possible to provide an electrode wire for electrical discharge machining that forms grains, cracks, and pinholes of the β' phase on the outermost layer of the electrode wire, and forms a fine space composed of a cave-like ε phase and a γ phase + ε phase deeper than the cracks in the direction of the core wire on the surface of the electrode wire, so that the cooling water provided under high pressure can penetrate into the core wire, thereby maximizing the cooling effect and not generating fine debris;

[0037] It is possible to provide an electrode wire for electrical discharge machining that forms β' phase grains and cracks on the surface of the electrode wire, which are more uniform than the γ phase cracks, compared with the existing electrode wire that forms γ phase grains on the surface of the electrode wire;

[0038] In the present invention, a conductive polymer is coated on the surface of the electrode wire to increase the conductivity of the electrode wire surface, thereby further improving the machining speed;

[0039] It is possible to provide an electrode wire for electrical discharge machining that coats a semiconductor or insulator polymer on the surface of the electrode wire, or forms an oxide layer with semiconductor or insulating properties, making the irregular discharge current uniform, reducing microcracks generated on the surface of the workpiece, etc., so as to improve the surface roughness and precision;

[0040] In the present invention, a conductive polymer or a semiconductor polymer or an insulator polymer is coated on the surface of the electrode wire, so that the detachment of fine debris can be prevented, and further the effect of preventing re-discharge due to fine debris can be achieved. Description of the Drawings

[0041] Figure 1 is a binary phase diagram of copper-zinc;

[0042] Figure 2 is a comparison chart of the state diagram and hardness of the Brinell hardness of "hyper Zn" in a copper-zinc binary alloy with the zinc content reaching more than 50 weight percent according to the phase change of the copper-zinc binary alloy;

[0043] Figure 3 is a schematic diagram showing the cross-section of an existing electrode wire for electrical discharge machining that forms cracks on the γ phase grains and the surface alloy layer of the electrode wire;

[0044] Figure 4 is a picture of the cross-section of the electrode wire for electrical discharge machining of the present invention magnified 3000 times;

[0045] Figure 5 is a magnified picture of the surface of the electrode wire for electrical discharge machining of the present invention;

[0046] Figure 6 It is a picture with the surface of the electrode wire for electrical discharge machining of the present invention magnified 1000 times;

[0047] Figure 7 It is a picture with the cross-section of the electrode wire for electrical discharge machining of the present invention magnified 3000 times;

[0048] Figure 8 It is a test table of the microspace components of the cave morphology of the electrode wire for electrical discharge machining of the present invention;

[0049] Figure 9 It is a test table of the pinhole components of the electrode wire for electrical discharge machining of the present invention;

[0050] Figure 10 It is a magnified picture of the surface of the intermediate wire of the electrode wire for electrical discharge machining of the present invention;

[0051] Figure 11 It is the characteristic value of the conductivity of the conductive polymer;

[0052] Figure 12 It is a comparison picture of the anti-corrosion effect of the surface of the iron plate coated with the conductive polymer. Detailed Description of the Preferred Embodiments

[0053] The electrode wire for electrical discharge machining according to the preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] The electrode wire for electrical discharge machining according to the preferred embodiment of the present invention is as shown in Figure 4 the magnified cross-sectional picture, and includes a core wire and an alloy layer.

[0055] The core wire is a wire formed of a first metal located in the main core part of the electrode wire. As the wire material of the first metal, various metals can be used. For example, one of copper, brass, or a copper-containing metal can be used. Preferably, a brass core wire with a copper weight percentage of 65: a zinc weight percentage of 35, or a copper weight percentage of 63: a zinc weight percentage of 37, or a copper weight percentage of 60: a zinc weight percentage of 40 can be used. Here, the core wire is surrounded by the alloy layer described later on its outer periphery, but according to the manufacturing process, at least a part of the core wire drills up from the alloy layer described later and is exposed on the surface of the electrode wire. Therefore, the core wire components can be directly detected on the surface of the electrode wire.

[0056] The alloy layer is a layer formed on the outer surface of the core wire by the mutual diffusion of the second metal plated on the core wire and the core wire. The second metal is composed of any one of zinc, aluminum, tin, or their alloys with a vaporization temperature lower than that of the core wire. Preferably, zinc can be used.

[0057] The alloy layer includes Figure 1The part composed of the α phase + β" phase shown in the copper-zinc binary phase diagram, and the grains of the β" phase formed on the periphery of the part composed of the α phase + β" phase. At the part of the surface of the electrode wire, which is the periphery of the formed alloy layer, as Figure 4 shown in the enlarged cross-sectional view of

[0058] The part composed of the α phase + β' phase is the part with the composition shown as α + β' in the copper-zinc binary phase diagram illustrated in Figure 1 . It is formed to surround the core wire on the periphery of the core wire, and grains of the β" phase described later are provided on the periphery of the part composed of the α phase + β". Here, the part composed of the α phase + β' phase can pass through some of the grains of the β' phase described later and rise to the surface layer. In this case, although less, a part of the part composed of the α phase + β' phase will become the outermost surface layer of the alloy layer.

[0059] The grains of the β' phase are, as Figure 4 shown in the enlarged cross-sectional picture of

[0060] formed by embedding on the periphery of the part composed of the α phase + β' phase in order to have a recessed part in at least a part of the part composed of the α phase + β'. Depending on the position, the grains of the β' phase may be embedded in a wedge shape on the periphery of the part composed of the α phase + β', and cracks are formed in or around the grains of the β' phase.

[0061] The alloy layer may also include Figure 1 the part composed of grains of the β' phase + γ phase shown in the copper-zinc binary phase diagram illustrated in

[0062] The alloy layer is, as shown on the surface in Figure 6 the enlarged surface picture of Figure 7 and the enlarged cross-sectional picture of

[0063] In addition to cracks, micro-spaces in the form of pinholes or cavities can also be formed. The micro-spaces in the form of cavities are, as Figure 7As shown in the enlarged cross-sectional view, the surface of the electrode wire is recessed deeper than the crack toward the core wire, forming a microspace in the shape of a cave. The surface layer of the microspace is dezincified due to partial vaporization during manufacturing processes such as diffusion heat treatment and drawing, so the zinc concentration increases, and thus has Figure 1 and Figure 2 the γ-phase + ε-phase or ε-phase shown in the figure. Depending on the position, a part where the γ-phase + ε-phase and ε-phase are mixed may also appear. Figure 8 It shows that the surface layer of the microspace in the shape of a cave shows the γ-phase + ε-phase with 23.6% copper and 76.37% zinc.

[0064] In the above-mentioned microspace in the shape of a cave during electrical discharge machining, the cooling water provided under high pressure can penetrate into the core wire part (the microspace in the shape of a cave extends to the core wire part). Therefore, not only is the cooling effect greatly improved, but also the zinc components of the ε-phase and γ-phase + ε-phase that make up the surface layer of the microspace in the shape of a cave are easily vaporized and absorb heat, so the cooling effect is further improved, resulting in a significant increase in the electrical discharge machining speed.

[0065] In addition, the numerous pinholes that appear on the surface of the alloy layer can not only improve the cooling effect by increasing the surface area of the electrode wire, but also form the γ-phase + ε-phase and / or ε-phase with a low vaporization temperature through dezincification during diffusion heat treatment on the surface of the pinholes, thereby further improving the cooling effect during electrical discharge machining. Figure 9 It shows that the surface layer of the pinhole shown on the surface of the alloy layer is a phase with 13.90% copper and 86.10% zinc.

[0066] As described above, together with the crack, the microspace in the shape of a cave or the pinhole can maximize the cooling effect by greatly increasing the surface area of the electrode wire and improve the machining speed.

[0067] As described above, the electrode wire for electrical discharge machining of the present invention includes: a part composed of the α-phase + β'-phase formed around the core wire, and grains of the β'-phase embedded in the periphery of the part composed of the α-phase + β'-phase, and cracks are formed in or around the grains of the β'-phase. Generally, as in the past, when the surface layer of the electrode wire forms the γ-phase, the alloy layer of the γ-phase is as Figure 2 shown, with a hardness of 350 HB or more. Therefore, when drawing is performed with a brittle alloy layer, when it cannot withstand the drawing pressure and cracks are formed, fine debris will be generated and a large amount of it will adhere to the crack surface. The large amount of fine debris adhering to the crack surface will become an obstacle to improving the machining speed and surface roughness due to factors such as re-discharge during electrical discharge machining.

[0068] However, in the grains of the β'-phase of the present invention, the surface layer of the electrode wire is as Figure 2As shown, it has a much lower hardness than the existing γ-phase alloy layer and is flexible, so it will not break during the drawing process, and almost no fine chips will adhere to the surface of the electrode wire. Therefore, during electrical discharge machining, secondary discharges caused by fine chips can be reduced, thereby greatly improving the machining speed and surface roughness. It can also prevent phenomena such as blockage of the diamond guide dies through which the electrode wire passes.

[0069] On the other hand, when comparing the vaporization temperature of the γ-phase and the vaporization temperature of the β'-phase, since the vaporization temperature of the γ-phase is lower than that of the β'-phase, generally, the machining speed of the traditional electrode wire with the γ-phase is faster than that of the electrode wire with the β'-phase.

[0070] However, for the electrode wire of the present invention, even though most of the surface of the alloy layer is formed by grains of the β'-phase with a higher copper concentration and a lower zinc concentration compared to the γ-phase, which was generally considered to be the fastest in the past, almost no fine chips adhere to the surface of the alloy layer of the present invention. And the grains of the β'-phase, numerous cracks, and numerous pinholes are mainly formed around the grains of the β'-phase, and the fine spaces in the form of cavities formed by the γ-phase + ε-phase or ε-phase extend to parts deeper than the cracks or pinholes. The cooling water provided under high pressure penetrates into the core wire to form numerous elements that can significantly improve the cooling effect. Therefore, compared with the existing electrode wire with cracks formed on the γ-phase, the machining speed can be increased by at least more than 108%.

[0071] The manufacturing method of the electrode wire for electrical discharge machining according to a preferred embodiment of the present invention having the above structure will be described below.

[0072] The manufacturing method of the electrode wire for electrical discharge machining of the present invention relates to the manufacturing method of the above electrode wire. The specific embodiment is implemented through a core wire providing step, a plating step, a first diffusion heat treatment step, a first drawing step, a second diffusion heat treatment step, and a second drawing step.

[0073] In the core wire providing step, a brass (65%: 35%) wire with a wire diameter of 2 mm (first diameter) is provided as the core wire of the first metal.

[0074] In the plating step, as a step of obtaining a galvanized wire by electroplating zinc, which has a lower vaporization temperature than the core wire, with a second metal, while moving the core wire to a drum, it is immersed in an electro-galvanizing bath and passed through at a predetermined speed to form a galvanized layer (second metal) with a thickness of about 12 μm around the core wire.

[0075] In the first diffusion heat treatment step, the galvanized wire is passed through the preheating section of an electric heating processor, the temperature between the electrodes is heated to a temperature of about 400 °C, and it is passed through at a speed of about 200 m / min for diffusion heat treatment, thereby forming an alloy layer around the intermediate wire.

[0076] The first drawing step is to perform a drawing process with a wire diameter of 1.2 mm (second diameter) on the intermediate wire after diffusion heat treatment, forming cracks on the surface of the intermediate wire. Figure 10 It shows cracks appearing on the surface of the intermediate wire.

[0077] The second diffusion heat treatment step is to heat the intermediate wire drawn for the first time for about 2 hours and then heat it at 400 °C for 20 hours to perform diffusion heat treatment, and open it after 6 hours, increasing the ratio of the copper (Cu) content diffused in the grain part where cracks are formed, and then converting it into grains of the β' phase.

[0078] The second drawing step is to use the intermediate wire after the second diffusion heat treatment to manufacture the electrode wire for electrical discharge machining of the present invention on an automated device capable of simultaneously performing a second drawing process that can achieve the standard wire diameter of the electrode wire, i.e., 0.25 mm, and stabilizing heat treatment. Figure 5 It is an enlarged surface picture of the electrode wire of the present invention finally manufactured. In the picture, the grains and crack parts on the β' phase are clearly shown. Figure 5 The grains in the crack part shown in Figure 10 Compared with the grains in the crack part of the intermediate wire shown in Figure 5 , it can be seen that the area of the grains is further enlarged. Due to the broadening of the grains, in Figure 10 , the occurrence of fine debris is significantly reduced compared with the crack part shown in Figure 4 It is an enlarged cross-sectional picture of the electrode wire manufactured by the above method. In the picture, it can be seen that the grains are embedded in the concave part of the alloy layer. Figure 6 It is an enlarged surface picture of the electrode wire. Cracks, pinholes, and micro spaces in the shape of caves can be seen on the surface layer. Figure 7 It is an enlarged cross-sectional picture of the electrode wire. Micro spaces in the shape of cracks and caves can be seen.

[0079] The above manufacturing method can, within the scope of not departing from the basic concept of the present invention, be selected and deformed accordingly for the diffusion heat treatment method, diffusion heat treatment temperature, time, gold plating method, and other processes according to the equipment owned by each company.

[0080] The results of trial machining of the workpiece using the electrode wire with a wire diameter of Ø0.25 mm of the present invention manufactured as described above and the electrode wires of Comparative Examples 1 and 2 are shown in Table 1 below.

[0081]

[0082] [Table 1]

[0083] The above-mentioned test machining examples shown in Table 1 were carried out on a Charmilles Robofil 240SL in Switzerland with ST25A. Tec. The workpiece was an alloy tool steel of SKD-11 (1.5C-12Cr-1Mo-0.35V). A workpiece with a Rockwell hardness of 58-65 and a height of 40 mm and a thickness was cut in the form of a square rod with a length x width = 10 mm x 10 mm.

[0084] Comparative Example 1 was Thermo JP2 of the French company Thermocompact, which is an electrode wire with a wire diameter of Ø 0.25 mm that forms cracks on the surface of the γ-phase alloy layer. Comparative Example 2 was Topas PLUS H of the German company Berkenhoff, which is an electrode wire with a wire diameter of Ø 0.25 mm that forms cracks on the surface of the γ-phase alloy layer.

[0085] As shown in the above test results, using the electrode wire of the present invention and Comparative Examples 1 and 2, under the conditions of standard parameters commonly used in the production workshop, when the electrical discharge machining was carried out to the second machining respectively, it was found that compared with Comparative Example 1, the electrode wire of the present invention had at least a machining speed increase of more than 108% in the first machining, and the highest machining speed increase of 114% in the second machining.

[0086] In the above illustrative example, the alloy layer of the electrode wire includes a part composed of the α-phase + β'-phase and the grains of the β'-phase formed on the outer periphery of the part composed of the α-phase + β'-phase. However, it can also be manufactured such that by changing partial diffusion heat treatment conditions or drawing processes, etc., most of the surface of the alloy layer has grains of the β'-phase, and a part can also be mixed with grains of the γ-phase or grains of the γ-phase + ε-phase.

[0087] The electrode wire manufactured as described above has most of the surface of the alloy layer composed of grains of the β'-phase, and a part composed of the α-phase + β'-phase and grains of the γ-phase or grains of the γ-phase + ε-phase will be mixed and appear.

[0088] According to the electrode wire of the present invention, an oxide layer can be formed on the part of the β'-phase grains and the part composed of the α-phase + β'-phase that are exposed on the surface of the electrode wire and on the surface layer of the micro spaces formed in the form of cracks, pinholes, and cavities. If an oxide layer is formed on the surface of the electrode wire and the micro spaces in the form of cavities, the oxide layer can promote the absorption of cooling water, increase the conductivity, and increase the discharge power, thereby further improving the machining speed.

[0089] According to the electrode wire of the present invention, a conductive polymer is coated on the surface of the electrode wire to increase the conductivity of the electrode wire surface and inhibit the generation of ultrafine powder, thereby improving the machining speed.

[0090] Conductive polymers are as Figure 11 shown by the conductivity characteristic value of 0 10 s / cm or more, which is very excellent, and doped poly(3,4-ethylenedioxythiophene) (doped PEDOT), doped polyaniline, etc. can be used. Figure 12 This is an example of a metal corrosion prevention experiment using doped polyaniline. Figure 12 (A) of Figure 12 shows the surface state of an iron plate. Figure 9 (B) of Figure 12 is a picture of the state of a chlorine spray test for corrosion resistance, in which after coating the surface of the iron plate shown in (A) of

[0091] with polyaniline and spraying a 0.5 M sodium chloride solution to promote corrosion. It can be seen from the picture (B) of

[0092] Figure 12

[0093] The technical structure of the electrode wire for electrical discharge machining of the present invention described above is only used to illustrate the technical solution of the present invention, rather than limiting it. Those of ordinary skill in the art can still modify the technical solutions described in the foregoing embodiments, and these modifications do not cause the essence of the corresponding technical solutions to deviate from the technical idea and purpose of the present invention.

[0094] Industrial Application

[0095] For the electrode wire for electrical discharge machining of the present invention, since the generation of fine debris during electrical discharge machining is minimized, no re-discharge phenomenon will occur, the machining speed is increased, and the surface roughness of the workpiece is greatly improved.

Claims

1. An electrode wire for electrical discharge machining, characterized in that, comprising: a core wire formed of a first metal; a second metal plated on the outer surface of the core wire forms an alloy layer on the outer periphery of the core wire through mutual diffusion with the core wire; the alloy layer includes: a part composed of α phase + β' phase; grains of β' phase formed on the outer periphery of the part composed of the α phase + β' phase; cracks are formed on the surface of the alloy layer; pinholes are also formed on the surface of the alloy layer; the surface layer of the pinholes is formed of at least one of γ phase + ε phase and ε phase; microscopic spaces in the form of caves that are deeper than the cracks are formed on the surface of the alloy layer in the direction of the core wire; the surface layer of the part having the microscopic spaces in the form of caves is formed of at least one of γ phase + ε phase and ε phase.

2. The electrode wire for electrical discharge machining according to claim 1, characterized in that, at least a part of the outer periphery of the part composed of the α phase + β' phase forms a recessed part; the grains of β' phase are formed by being embedded in the recessed part formed on the outer periphery of the part composed of the α phase + β' phase.

3. The electrode wire for electrical discharge machining according to claim 1, characterized in that, the grains of β' phase are formed by being embedded in a wedge shape on the periphery of the part composed of the α phase + β' phase.

4. The electrode wire for electrical discharge machining according to claim 1, characterized in that, the grains of β' phase are discontinuously formed on the periphery of the part composed of the α phase + β' phase.

5. The electrode wire for electrical discharge machining according to claim 1, characterized in that, the alloy layer further includes grains of β' phase + γ phase.

6. The electrode wire for electrical discharge machining according to any one of claims 1 to 5, characterized in that, cracks are formed on the grains of β' phase.

7. The electrode wire for electrical discharge machining according to any one of claims 1 to 5, characterized in that, at least a part of the core wire drills through the alloy layer and is exposed on the surface of the electrode wire.

8. The electrode wire for electrical discharge machining according to claim 1, characterized in that, the surface of the alloy layer is coated with at least one of an oxide layer, a conductive polymer, a semiconductor polymer, and an insulating polymer.

9. The electrode wire for electrical discharge machining according to any one of claims 1 to 5, characterized in that, the first metal is one of the copper-containing metals, and the second metal is formed of any one of zinc, aluminum, tin, or their alloys.

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