A composite electrode wire for wire cutting of cemented carbide materials and its preparation method

Abstract

This invention discloses a composite electrode wire for wire EDM of cemented carbide materials and its preparation method. The composite electrode wire comprises a brass core with a zinc content of 20%-43% and a copper-zinc alloy surface layer with a zinc content of 40%-85%. The copper-zinc alloy surface layer has irregularly distributed micro- and nano-pores, each extending to the surface of the electrode wire. Semiconductor-functional particles are adhered within the micro- and nano-pores and on the electrode wire surface. These semiconductor-functional particles are compound semiconductor materials formed by metal and oxygen, and are one or more of ZnO, CuO, NiO, Cu2O, and SnO2. The preparation steps include electrodepositing a zinc-based composite layer on the surface of the brass core and adhering semiconductor-functional particles within the micro- and nano-pores and on the electrode wire surface. This composite electrode wire can significantly increase wire EDM speed and achieve relatively high processing accuracy, significantly improving the surface marks on the cut workpiece and enhancing the surface quality of the cut.

Description

Technical Field

[0001] This invention relates to the field of electrode wire technology for unidirectional wire-fed electrical discharge machining, specifically a composite electrode wire for wire cutting of cemented carbide materials and its preparation method. Background Technology

[0002] In existing technologies, motor molds are widely used in fields such as automobile manufacturing, aerospace, metallurgical machinery, and home appliances. Motor molds made of hard alloy materials such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt have the characteristics of high efficiency, high precision, fast mold changeover, and long service life in the motor production process.

[0003] However, the hard alloy materials such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt used to make motor molds have the characteristics of high hardness, corrosion resistance, high temperature resistance and small expansion coefficient. Compared with traditional ordinary mold materials such as SKD11, DC53 and SKH-9, they are more difficult to process.

[0004] On the other hand, slow wire EDM, also known as unidirectional wire EDM, is a machining method that uses a continuously moving fine metal wire, i.e., an electrode wire, as the electrode to perform pulsed spark discharge on the workpiece to remove metal and cut it into shape. Slow wire EDM is also widely used in mold manufacturing, especially in the field of motor mold processing. For example, in the field of motor mold processing, slow wire EDM can achieve high-precision EDM, and perform free-form and free-shape wire cutting of hard alloy materials such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt.

[0005] While unidirectional wire EDM, as a precision machining method, can effectively cut these cemented carbide materials, its cutting speed is relatively slow. This is because cemented carbide materials have extremely high hardness, requiring higher energy and stability in EDM to ensure both cutting speed and machining quality. Furthermore, the complex shapes and precision machining requirements of cemented carbide materials, necessitating multiple tool dressing operations, are also major reasons for the slow cutting speed.

[0006] Although existing technologies provide support in terms of equipment and technology such as anti-electrolysis power supplies, optimized discharge parameters, multiple cutting techniques, and high-precision corner control, the processing of some special materials, such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt, is still limited by the material properties, and their cutting speed, processing accuracy, and surface quality urgently need to be further improved.

[0007] For example, in the prior invention patent of this applicant with application number 202010509917.X, entitled "An Electrode Wire for Micro-Electro-Discharge Machining, Preparation Method and Application" (hereinafter referred to as Patent 2), the mixed structure of the amorphous layer of the electrode wire reduces the discharge loss of the electrode wire itself. In the processing of ordinary mold materials, continuous and stable micro-electro-discharge corrosion can be achieved, ensuring a constant gap between the electrode wire and the micro-tool electrode, and improving the online machining accuracy and surface quality. Moreover, the main metal element of the amorphous surface layer is zinc, which has good vaporization effect, which helps to improve the discharge efficiency and can increase the processing speed of ordinary mold materials. However, in the wire cutting of cemented carbide materials, due to the random arrangement and long-range disorder of the atoms in the amorphous layer, the resistivity is high, resulting in relatively poor conductivity of the electrode wire material surface, making it difficult to further increase the wire cutting speed of cemented carbide materials.

[0008] For example, existing electrode wires such as galvanized wire, gamma wire, and high-speed coated wire achieve good rinsing effects by increasing the zinc content of the surface layer, but the conductivity of the surface material still cannot meet the requirements of rapid electron migration and discharge, which also makes it difficult to further improve the wire cutting speed of cemented carbide materials.

[0009] For example, the applicant's prior invention patent (hereinafter referred to as Patent 1) with application number 202111210891.X and titled "An Electrode Wire for Electrical Discharge Machining and Its Preparation Method" has a low thermal conductivity on the surface of the electrode wire. In the processing of ordinary mold materials, the heat generated by the electrical discharge can be more concentrated on the surface of the electrode wire, and stronger vaporization pressure is generated when it is vaporized, which further improves the rinsing effect and increases the cutting speed. However, since the surface layer of the electrode wire is composed of a mixture of materials, it has good technical effects for wire cutting of ordinary mold materials, but for cemented carbide with relatively poor conductivity, the electrode wire is not sensitive enough to microcurrent contact when it touches the edge, and the edge contact accuracy is not ideal, which directly affects the processing accuracy and surface quality of cemented carbide materials.

[0010] For example, high-speed coated wires, which are widely used in the market, generally have a β-phase or β+γ-phase, or β'+γ-phase or β'-phase composition. The coating is thick and more corrosion-resistant than zinc-plated layers when wire cutting ordinary mold materials. It also has a strong and continuous vaporization flushing effect and a fast cutting speed. However, when applied to wire cutting of cemented carbide, the thick coating and deep cracks severely reduce the conductivity of the electrode wire surface. This causes the high-speed coated wire to fail to discharge under the weak discharge energy during fine finishing, making it prone to short circuits. Furthermore, it reduces the uniformity of discharge during fine finishing, thus affecting the processing accuracy and surface quality. Summary of the Invention

[0011] One technical problem to be solved by the present invention is to provide a composite electrode wire for wire cutting of cemented carbide materials, which can significantly improve the wire cutting speed and the machining accuracy is relatively high, and can significantly improve the surface marks on the cut workpiece and improve the surface quality of the cut.

[0012] One technical solution of the present invention is to provide a composite electrode wire for wire cutting of cemented carbide materials, comprising a brass core with a zinc content of 20%-43% and a copper-zinc alloy surface layer with a zinc content of 40%-85%; the copper-zinc alloy surface layer is distributed with irregular micro-nano holes, each micro-nano hole extending to the surface of the electrode wire; and semiconductor particles are adhered in the micro-nano holes and on the surface of the electrode wire.

[0013] With the above content and structure, the composite electrode wire for wire cutting cemented carbide materials of the present invention has the following advantages:

[0014] The composite electrode wire of this invention has irregularly distributed micro- and nano-pores on its copper-zinc alloy surface. Semiconductor-functional particles adhere to both the micro- and nano-pores and the electrode wire surface, allowing for rapid charge accumulation and the construction of an effective conductive network. This significantly enhances the conductivity of the electrode wire surface material under high-temperature conditions. These particles, under the action of a pulsed power supply, interconnect and generate a large amount of small current accumulation, eventually converging to form a discharge channel. This accelerates electron mobility, enabling pulsed spark discharge on the workpiece, generating temperatures above 8000-10000℃. This process erodes metal, cuts and shapes the workpiece, and increases the cutting speed of machine tools for preparing hard alloy materials such as tungsten steel, tungsten-titanium-cobalt, and tungsten-tantalum-cobalt used in motor mold making. The irregular micro- and nano-pores, with their varying micro-morphology and contact surface areas, allow for the introduction of more coolant, further improving the rinsing effect, promoting the next pulse discharge, and maximizing the cutting speed of the machine tool on cemented carbide materials. The semiconductor-functional particles adhering to the micro- and nano-pores and the electrode wire surface have relatively low impedance, resulting in better conductivity at high temperatures. Under the action of the pulse power supply, they can optimize the discharge gap between the electrode wire surface and the workpiece, collecting micro-currents to reduce the contact resistance of the electrode wire, accelerate electron movement, and effectively reduce discharge delay, rapidly increasing the discharge rate, thereby further enhancing the cutting speed of the machine tool on cemented carbide materials.

[0015] Meanwhile, due to the significantly improved conductivity of the electrode wire surface, when wire-cutting cemented carbide materials such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt, the electrode wire surface of this invention is highly sensitive to microcurrent contact when it touches the edge, and the edge-touching accuracy is greatly improved, thereby significantly improving the processing accuracy of cemented carbide materials.

[0016] Furthermore, the semiconductor-functional particles also act as conductivity promoters during the cutting discharge process, promoting the conductivity between the discharge active substances in the working fluid, reducing the contact resistance between electrodes, improving the uniformity of discharge, thereby improving the surface marks on the cut workpiece and enhancing the surface quality of the cut cemented carbide material.

[0017] In summary, the composite electrode wire for wire EDM of cemented carbide materials of this invention can significantly increase the wire EDM speed of cemented carbide materials, while maintaining relatively high machining accuracy. It can also significantly improve the quality of the cut surface by significantly reducing surface marks. It is also easy to understand that this composite electrode wire exhibits superior performance when wire cutting other metal materials.

[0018] Furthermore, the semiconductor-functional particles are compound semiconductor materials formed by metal and oxygen. With this structure, the conductivity of the electrode wire surface is improved, further enhancing the wire cutting speed, machining accuracy, and surface quality of the cut cemented carbide materials using this composite electrode wire.

[0019] Furthermore, the semiconductor-functional particles are all irregularly shaped, with the smallest individual particle size ranging from 1 to 4700 nm and the largest individual particle size ranging from 10 to 5000 nm. With this structure, the shape of the semiconductor-functional particles adheres better to the micro- and nano-pores and the electrode wire surface, and the size is better adapted to the micro- and nano-pores, resulting in better conductivity of the electrode wire surface. This further improves the wire cutting speed, machining accuracy, and cut surface quality of this composite electrode wire for cemented carbide materials.

[0020] Furthermore, the semiconductor-functional particles are one or more of ZnO, CuO, NiO, Cu2O, and SnO2. Using these specific oxides improves the conductivity of the electrode wire surface, further enhancing the wire cutting speed, machining accuracy, and surface quality of the cut cemented carbide materials using this composite electrode wire.

[0021] Furthermore, the radial depth dimension of the micro-nano aperture is greater than the circumferential width dimension; or the radial depth dimension of the micro-nano aperture is greater than the axial length dimension; or the radial depth dimension of the micro-nano aperture is greater than both the circumferential width dimension and the axial length dimension; or the radial depth dimension of the micro-nano aperture is less than the circumferential width dimension; or the radial depth dimension of the micro-nano aperture is less than both the circumferential width dimension and the axial length dimension. With the above structure, the irregular micro-nano apertures are better distributed along the circumference and length of the electrode wire surface, resulting in better distribution of semiconductor functional particles. This further improves the conductivity of the electrode wire during wire cutting, and further enhances the wire cutting speed, machining accuracy, and cut surface quality of this composite electrode wire for cemented carbide materials.

[0022] Furthermore, the thickness of the copper-zinc alloy surface layer is 2-40 μm; the width of each micro-nano hole on the cross-section of the electrode wire is 0.1-60 μm, and the depth is 0.2-45 μm; the length of each micro-nano hole on the longitudinal section of the electrode wire is 0.1-40 μm, and the depth is 0.2-45 μm. By adopting these parameters, the distribution of semiconductor functional particles with micro-nano holes along the circumference and length of the electrode wire surface is further improved, further enhancing the conductivity of the electrode wire during wire cutting, and further improving the wire cutting speed, processing accuracy, and cut surface quality of this composite electrode wire for cemented carbide materials.

[0023] Furthermore, several micro- and nano-pores are arranged along the circumference and length of the electrode wire; the semiconductor-functional particles adhering to the micro- and nano-pores and the electrode wire surface each consist of several particles. This structure further improves the distribution of semiconductor-functional particles along the circumference and length of the micro- and nano-pores on the electrode wire surface, further enhancing the conductivity of the electrode wire during wire cutting, and further improving the wire cutting speed, processing accuracy, and surface quality of the composite electrode wire for cemented carbide materials.

[0024] Another technical problem to be solved by the present invention is to provide a method for preparing a composite electrode wire for wire cutting of cemented carbide materials, which can produce a composite electrode wire for wire cutting of cemented carbide materials with high wire cutting speed, high processing accuracy and good cutting surface quality.

[0025] Another technical solution of the present invention is to provide a method for preparing a composite electrode wire for wire cutting of cemented carbide materials, comprising the following preparation steps:

[0026] 1) Prepare brass core material with a diameter of 0.7-1.5 mm and a zinc content in the range of 20% to 43%;

[0027] 2) Electroplating a zinc-based surface layer onto the brass core material obtained in step 1), with an electroplating speed of 300-800 m / min, a current of 500-2000 A, a voltage of 5-20 V, and a surface layer thickness of 1-30 μm;

[0028] 3) The wire blank obtained after electroplating is first stretched to a diameter of 0.5-1.0 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material, and a dense wire blank with a zinc-based composite layer is obtained from the first stretching.

[0029] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 150-300℃ for 0.5-20h. It is then cooled in the furnace to below 100℃ and removed from the furnace to obtain a heat-treated wire blank with a copper-zinc alloy surface layer having a gamma phase structure.

[0030] 5) The heat-treated wire blank is stretched a second time through a wire drawing die to obtain a semi-finished wire blank including a brass core and a copper-zinc alloy surface layer with micro-nano holes. The diameter of the semi-finished wire blank is 0.35-0.85mm.

[0031] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 300-500℃ for 2-30 hours. After cooling in the furnace to below 150℃, the wire blank is obtained with a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes and electrode wires. The semiconductor material includes at least zinc oxide and the zinc content of the copper-zinc alloy surface layer is 40%-85%.

[0032] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 500-2000 m / min and then subjected to stress-relief annealing to obtain an electrode wire finished product with a diameter of 0.15-0.30 mm.

[0033] After adopting the above preparation steps, a method for preparing a composite electrode wire for wire cutting cemented carbide materials has the following advantages:

[0034] The preparation method of this invention focuses on two key process steps: first, electrodepositing a zinc-based composite layer on the surface of a brass core; second, adhering semiconductor-functional particles, such as zinc oxide and copper oxide particles, to the micro- and nano-pores and the surface of the electrode wire. Through heat treatment, the trace elements on the surface diffuse and transfer from high-concentration areas to low-concentration areas, resulting in a more uniform distribution. This invention's preparation method can produce composite electrode wires for wire cutting of cemented carbide materials that offer high wire cutting speed, high processing accuracy, and excellent surface finish.

[0035] Furthermore, in step 2), during the electrolysis process, 1-30 kg of 0# zinc blocks with a zinc content of not less than 99.995% are added to each ton of electrodeposition bath. The brass core material serves as the cathode, and the zinc blocks as the anode. After energization, the zinc ions on the zinc blocks lose electrons under the influence of the current and dissolve into the electrolyte to form zinc ions. These zinc ions move towards the surface of the brass core material under the influence of the electric field, gain electrons on the surface, and are reduced to metallic zinc, thus forming a zinc plating layer on the surface of the brass core material. Using the above preparation process steps, the process is simple and reliable, forming a stable and reliable zinc plating layer on the surface of the brass core material, laying a good foundation for the next step of preparing a high-quality copper-zinc alloy surface layer.

[0036] Further, in step 2), one or two trace elements Ni and Sn are added to the electroplating bath, specifically nickel sulfate and / or tin sulfate, with a concentration of 1-100 g / L for each trace element. This results in the zinc-based surface layer also containing trace elements Ni and / or Sn, forming a zinc-based composite surface layer. The semiconductor material mentioned in step 6) also includes copper oxide, / and cuprous oxide, / and nickel oxide, / and tin oxide. After the above preparation steps, the copper-zinc alloy surface layer adsorbs a wider variety of trace elements, further improving the conductivity of the electrode wire during wire cutting, and further enhancing the wire cutting speed, processing accuracy, and surface quality of the cut cemented carbide material using this composite electrode wire.

[0037] Further, in step 6), the chemical reaction process is as follows: 2Zn + O2 → 2ZnO, or / and 2Cu + O2 → 2CuO, or / and 4Cu + O2 → 2Cu2O, or / and 2Ni + O2 → 2NiO, or / and Sn + O2 → SnO2.

[0038] After employing the above preparation process, zinc oxide is a wide-bandgap semiconductor, characterized by its wide bandgap, high saturated electron drift velocity, and high electron mobility. Therefore, the energy difference between the lower energy level of the conduction band and the highest energy level of the valence band in zinc oxide is very small, and their electron transition energies are very close. This results in the electrode wire of this invention exhibiting faster response speed and higher working efficiency under high-temperature electrical discharge conditions. Meanwhile, copper oxide crystal structure contains ionic bonds between Cu and O atoms. In copper oxide, the Cu atom loses one electron, becoming Cu... 2+ The ion, while the O atom gains an electron, becoming an O atom. 2- Ions. Copper oxide contains vacant oxygen ions, and these vacancies attract free electrons, thus forming a hole-type semiconductor. Therefore, the conductivity of copper oxide is temperature-dependent, improving with increasing temperature. Furthermore, copper oxide simultaneously enhances the reversible capacity, cycle life, and charge-discharge stability of the electrode wire during discharge. Therefore, zinc oxide, copper oxide, cuprous oxide, nickel oxide, and tin oxide all rapidly generate and increase a large number of electron-hole pairs with increasing temperature, thereby reducing the resistivity of the electrode wire, significantly improving the conductivity of the product, and thus greatly increasing the electron transport speed. They exhibit excellent discharge performance and thermal stability, enabling the prepared composite electrode wires to be used for wire cutting of cemented carbide materials, resulting in high wire cutting speed, high machining accuracy, and good cut surface quality.

[0039] Furthermore, the obtained electrode wire has a tensile strength of 750-1100 MPa and a conductivity of 19%-28% IACS. The composite electrode wire, possessing these properties, further ensures the technical advantages of high wire cutting speed, high processing accuracy, and good cutting surface quality. Attached Figure Description

[0040] Figure 1 This is a cross-sectional enlarged schematic diagram of the composite electrode wire of the present invention (the electrode wire surface is adhered with particles having semiconductor functions). Figure 1 and Figure 2 (Not shown in the text).

[0041] Figure 2 This is a longitudinal section enlarged schematic diagram of a segment of the composite electrode wire of the present invention.

[0042] As shown in the figure:

[0043] 1. Brass core material, 2. Copper-zinc alloy surface layer, 3. Micro-nano pores, 4. Particles with semiconductor function. Detailed Implementation

[0044] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions of specific embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various specific embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] like Figure 1 and Figure 2 As shown.

[0046] This invention discloses a composite electrode wire for wire cutting of cemented carbide materials, comprising a brass core 1 with a zinc content of 20%-43% and a copper-zinc alloy surface layer 2 with a zinc content of 40%-85%. The copper-zinc alloy surface layer 2 has irregularly distributed micro-nano holes 3, each extending to the surface of the electrode wire. Semiconductor-functional particles 4 are adhered within the micro-nano holes 3 and to the surface of the electrode wire.

[0047] The semiconductor-functional particles are compound semiconductor materials 4 formed from metal and oxygen. These semiconductor-functional particles 4 are all irregularly shaped, with a minimum size of 1-4700 nm and a maximum size of 10-5000 nm. It is easy to understand that 4700 nm is equivalent to 4.7 μm, which is 4.7 kilonanometers or 4.7 micrometers; and 5000 nm is equivalent to 5 μm, which is 5 kilonanometers or 5 micrometers.

[0048] Because the composite electrode wire of this invention includes zinc and copper, the semiconductor-functional particle 4 must include at least ZnO (zinc oxide), as zinc is more easily oxidized than copper, even at slightly lower temperatures and for shorter periods, thus ensuring the presence of zinc oxide. It may also include CuO (copper oxide) and Cu2O (cuprous oxide). It's easy to understand that copper oxide is formed when there is less copper and more oxygen, while cuprous oxide is formed when there is more copper and less oxygen. In step 2), if Ni is added, it includes NiO (nickel oxide); if Sn is added, it includes SnO2 (tin oxide).

[0049] The radial depth of the micro-nano aperture 3 is greater than its circumferential width; or the radial depth of the micro-nano aperture 3 is greater than its axial length; or the radial depth of the micro-nano aperture 3 is greater than both its circumferential width and axial length; or the radial depth of the micro-nano aperture 3 is less than its circumferential width; or the radial depth of the micro-nano aperture 3 is less than its axial length; or the radial depth of the micro-nano aperture 3 is less than both its circumferential width and axial length. See also Figure 2 The radial depth dimension b of the upper micro-nano hole is greater than the axial length dimension a; the length dimension a of the lower micro-nano hole is greater than the radial depth dimension b.

[0050] The thickness of the copper-zinc alloy surface layer of the final product is preferably 2-40 μm; the width of each micro-nano hole on the cross-section of the electrode wire is preferably 0.1-60 μm and the depth is preferably 0.2-45 μm; the length of each micro-nano hole on the longitudinal section of the electrode wire is preferably 0.1-40 μm and the depth is preferably 0.2-45 μm.

[0051] Several micro- and nano-pores 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. There are several micro- and nano-pores 3 and semiconductor-functional particles 4 adhering to the surface of the electrode wire.

[0052] It is not difficult to understand that during the stretching process, some micro-nano pores 3 coated with semiconductor particles 4 do not extend to the surface of the electrode wire, but this has no side effects. It just means that the semiconductor particles 4 inside cannot conduct electricity.

[0053] This invention discloses a method for preparing a composite electrode wire for wire cutting of cemented carbide materials, comprising the following preparation steps:

[0054] 1) Prepare brass core material with a diameter of 0.7-1.5 mm and a zinc content in the range of 20% to 43%;

[0055] 2) A zinc-based surface layer is electroplated onto the surface of the brass core material obtained in step 1). One or two trace elements, Ni and Sn, can be added to the electroplating bath. Specifically, nickel sulfate and / or tin sulfate are added, with a concentration of 1-100 g / L for each trace element. This results in the zinc-based surface layer also containing trace elements nickel and / or tin, forming a zinc-based composite layer. Alternatively, trace elements may not be added. Since the composite electrode wire of this invention includes copper and zinc, the semiconductor-functional particles 4 at least include ZnO (zinc oxide) and may also include CuO (copper oxide) and Cu2O (cuprous oxide). Add 1-30 kg of 0# zinc blocks to each ton of electrodeposition bath solution, with a zinc content of not less than 99.995%. Use a brass core as the cathode and the zinc blocks as the anode. When electricity is applied, the zinc ions on the zinc blocks lose electrons under the influence of the current and dissolve into the electrolyte to form zinc ions. These zinc ions move towards the surface of the brass core under the influence of the electric field and gain electrons on the surface of the brass core, reducing to metallic zinc, thus forming a zinc plating layer on the surface of the brass core. The electroplating speed is 300-800 m / min, the current is 500-2000 A, the voltage is 5-20 V, and the surface layer thickness is 3-30 μm.

[0056] 3) The wire blank obtained after electroplating is stretched to a diameter of 0.5-1.0 mm by a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense wire blank with a zinc-based composite layer is obtained by the first stretching.

[0057] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 150-300℃ for 0.5-20h. It is then cooled in the furnace to below 100℃ before being removed from the furnace to obtain a heat-treated wire blank with a copper-zinc alloy surface layer and a composite surface layer with more uniform trace elements.

[0058] 5) The heat-treated wire blank is stretched a second time through a wire drawing die to obtain a semi-finished wire blank including a brass core material 1 and a copper-zinc alloy surface layer 2 with micro-nano holes 3. The diameter of the semi-finished wire blank is 0.35-0.85mm.

[0059] 6) The semi-finished wire blank obtained from the second stretching is heat-treated in an air atmosphere in a furnace at a temperature of 300-500℃ for 2-30 hours. After cooling in the furnace to below 150℃, the wire blank is obtained with semiconductor-functional particles 4 formed by metal and oxygen in the air adhering to the micro-nano holes 3 and the electrode wire surface, and the zinc content of the copper-zinc alloy surface layer 2 is 40%-85%. The chemical reaction process in this step is as follows: 2Zn + O2 → 2ZnO, or / and 2Cu + O2 → 2CuO, or / and 4Cu + O2 → 2Cu2O, or / and 2Ni + O2 → 2NiO, or / and Sn + O2 → SnO2. The semiconductor material includes at least zinc oxide, and also includes copper oxide, or / and cuprous oxide, or / and nickel oxide, or / and tin oxide.

[0060] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 500-2000 m / min and then subjected to stress-relief annealing to obtain an electrode wire finished product with a diameter of 0.15-0.30 mm.

[0061] The resulting electrode wire has a tensile strength of 750-1100 MPa and a conductivity of 19%-28% IACS.

[0062] It is easy to understand that in the preparation process, step 2) involves electroplating a zinc-based composite layer onto the surface of the brass core material 1, with a coating thickness of 1-30 μm. Subsequent processes involve two heat treatments. The first heat treatment is conducted at 150-300℃ for 0.5-20 hours, resulting not only in a composite surface containing gamma phase structure and more uniform trace elements, but also in the interdiffusion of chemical components between the core material and the coating, forming a new surface layer with a thickness of 2-50 μm. The second heat treatment temperature is 300-500℃, and the heat treatment time is 2h-30h. Not only are compound semiconductor materials formed by metal and oxygen in the air adhered in the micro-nano holes 3 and on the surface of the electrode wire, but the chemical composition of both also changes. The core material and the surface layer not only diffuse further after the second heat treatment, but also the original composite surface layer containing gamma phase structure is transformed into a copper-zinc alloy surface layer 2 with different phase structure, forming a zinc content of 40%-85%. More importantly, some surface metal elements such as one or more trace elements such as Zn, Cu, Ni and Sn, form compound semiconductor materials with oxygen in the air, namely particles 4 with semiconductor function, which adhere to the micro-nano holes 3 and the surface of the electrode wire. Therefore, the thickness of the copper-zinc alloy surface layer 2 of the electrode wire becomes thinner, such as 2-40μm.

[0063] Because the copper-zinc alloy surface layer 2 is relatively hard and brittle after two heat treatments in the subsequent process, it fractures after stretching to form micro-nano holes 2. Its surface thickness is basically maintained at 2-40μm. Meanwhile, the brass core material 1 has good plasticity and toughness. After two stretching processes in the subsequent process, the wire diameter gradually decreases, and finally, an electrode wire with a diameter of 0.15-0.30mm is obtained.

[0064] It is easy to understand that during the preparation of this composite electrode wire, such as electroplating, stretching and heat treatment, not all micro-nano holes 2 are necessarily filled with semiconductor functional particles 4, nor is the surface of the electrode wire necessarily uniformly and continuously covered with semiconductor functional particles 4, but this will not affect the technical effect described in this invention.

[0065] It's easy to understand that "single" can also be understood as "each". The zinc coating is also called a zinc-plated layer. The copper-zinc alloy surface layer 2 can also be called a zinc-copper alloy surface layer. KG stands for kilogram. The micro-nano holes 3 are blind holes, also called micro-nano pits or cracks. The micro-nano holes 3 can be through or not through the copper-zinc alloy surface layer, such as... Figure 1 As shown, five micro-nano holes 3 penetrate the copper-zinc alloy surface layer 2 in the cross-section, while the remaining micro-nano holes 3 do not penetrate the copper-zinc alloy surface layer 2. Figure 2 As shown, two micro-nano holes 3 penetrate the copper-zinc alloy surface layer 2 on the longitudinal section. Electroplating is also known as electrodeposition. Edge contact in wire EDM refers to the reference positioning at startup, determining the precise cutting start point and ensuring accurate alignment between the workpiece and the reference position to improve machining accuracy. Inductive edge contact refers to using a micro-current voltage to slowly move the die head during startup, causing the electrode wire to gradually approach the workpiece, achieving the corresponding edge contact accuracy. The level of edge contact accuracy directly affects the machining accuracy of wire EDM. Edge contact accuracy within 0.001-0.002mm is considered high-precision positioning, within 0.003-0.005mm meets basic positioning accuracy, and above 0.010mm is considered rough machining positioning accuracy. The edge contact accuracy of this invention falls within the high-precision positioning range described above. The more uniform distribution of trace elements in the composite surface layer described in step 4) can be understood as follows: through heat treatment, the trace elements in the surface layer diffuse into each other, transferring from high-concentration areas to low-concentration areas, making their distribution more uniform.

[0066] This invention can be used to cut composite electrode wires of cemented carbide materials in wire EDM machines manufactured by companies such as AgieCharmilles (Switzerland), Mitsubishi (Japan), Sodick (Japan), and Saibu (Japan) to cut cemented carbide materials such as tungsten steel, tungsten titanium cobalt, and tungsten tantalum cobalt in motor molds.

[0067] The following detailed description, in conjunction with embodiments, illustrates an electrode wire for wire electrical discharge machining and its preparation method according to the present invention.

[0068] Example 1

[0069] 1) Prepare a brass core material with a diameter of 1.2 mm and a zinc content of 37%;

[0070] 2) Electroplating a zinc-based surface layer on the surface of the brass core material 1 obtained in step 1), adding 20KG of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, an electroplating speed of 500m / min, a current of 1500A, a voltage of 15V, and a surface layer thickness of 6μm.

[0071] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.8 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0072] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 210℃ for 8 hours. It is then cooled in the furnace to below 100℃ and removed from the furnace to obtain a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0073] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.51 mm.

[0074] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 450°C for 10 hours. After cooling in the furnace to below 150°C, the wire blank is obtained after heat treatment. The wire blank has a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes 3 and the electrode wire, and the zinc content of the copper-zinc alloy surface layer 2 is 40%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO and 2Cu + O2 → 2CuO. The semiconductor material is specifically: a number of ZnO and CuO particles 4 with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the surface of the electrode wire.

[0075] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1250 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0076] The obtained electrode wire has a tensile strength of 870 MPa and a conductivity of 21% IACS. The final product has a surface thickness of 8 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-15 μm and the depth is 0.2-11 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.1-12 μm and the depth is 0.2-10 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 10 nm and a maximum size of 2000 nm.

[0077] Example 2

[0078] 1) Prepare a brass core material with a diameter of 1.0 mm and a zinc content of 20%;

[0079] 2) A zinc-based surface layer is electroplated on the surface of the brass core material 1 obtained in step 1). A trace element nickel, such as nickel sulfate, is added to the electroplating bath. The concentration of the trace element nickel is 80 g / L, so that the copper-zinc alloy surface layer contains trace elements zinc, copper and nickel to form a zinc-based composite surface layer. 15 kg of 0# zinc blocks are added to each ton of electrodeposition bath, with a zinc content of not less than 99.995%. The electroplating speed is 300 m / min, the current is 1200 A, the voltage is 12 V, and the surface layer thickness is 1 μm.

[0080] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.72 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0081] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 180℃ for 6 hours. It is then cooled in the furnace to below 100℃ before being removed from the furnace, resulting in a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0082] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.48 mm.

[0083] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 420°C for 10 hours. After cooling in the furnace to below 150°C, the wire blank is obtained after heat treatment. The wire blank has a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes 3 and the electrode wire, and the zinc content of the copper-zinc alloy surface layer 2 is 45%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO and 2Ni + O2 → 2NiO. The semiconductor material is specifically: a number of ZnO, CuO and NiO particles with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the surface of the electrode wire.

[0084] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1200 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0085] The obtained electrode wire has a tensile strength of 750 MPa and a conductivity of 28% IACS. The final product has a surface thickness of 2 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-3 μm and the depth is 0.2-3 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.1-2 μm and the depth is 0.2-2.5 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 10 nm and a maximum size of 1000 nm.

[0086] Example 3

[0087] 1) Prepare a brass core material with a diameter of 0.9 mm and a zinc content of 30%;

[0088] 2) A zinc-based surface layer is electroplated on the surface of the brass core material 1 obtained in step 1). Trace elements such as tin sulfate (Sn) are added to the electroplating bath. The concentration of the trace element tin is 60 g / L, so that the copper-zinc alloy surface layer 2 contains trace elements zinc and tin to form a zinc-based composite surface layer. 25 kg of 0# zinc blocks are added to each ton of electrodeposition bath. The zinc content is not less than 99.995%. The electroplating speed is 500 m / min, the current is 1800 A, the voltage is 16 V, and the surface layer thickness is 10 μm.

[0089] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.68 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0090] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 170℃ for 15 hours. It is then cooled in the furnace to below 100℃ and removed from the furnace to obtain a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0091] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.45mm.

[0092] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 455°C for 8 hours. After cooling in the furnace to below 150°C, the wire blank is obtained after heat treatment. The wire blank has a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes 3 and the electrode wire, and the zinc content of the copper-zinc alloy surface layer 2 is 50%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO and Sn + O2 → SnO2. The semiconductor material is specifically: a number of ZnO, CuO and SnO2 particles with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the surface of the electrode wire.

[0093] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 800 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0094] The obtained electrode wire has a tensile strength of 810 MPa and a conductivity of 26% IACS. The final product has a surface thickness of 14 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-15 μm and the depth is 0.2-16 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.1-10 μm and the depth is 0.2-12 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 10 nm and a maximum size of 3000 nm.

[0095] Example 4

[0096] 1) Prepare a brass core material with a diameter of 1.2 mm and a zinc content of 40%;

[0097] 2) Electroplating a zinc-based surface layer onto the surface of the brass core material 1 obtained in step 1), adding trace element Sn such as tin sulfate to the electroplating bath, wherein the concentration of trace element tin is 80 g / L, so that the copper-zinc alloy surface layer contains trace elements copper, zinc and tin to form a zinc-based composite surface layer; adding 25 kg of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, the electroplating speed is 550 m / min, the current is 1000 A, the voltage is 10 V, and the surface layer thickness is 15 μm;

[0098] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.91 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0099] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 250℃ for 15 hours. It is then cooled in the furnace to below 100℃ before being removed from the furnace, resulting in a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0100] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.65mm.

[0101] 6) The semi-finished wire blank obtained from the second stretching is heat-treated in an air atmosphere in a furnace at a temperature of 470°C for 18 hours. After cooling in the furnace to below 150°C, the wire blank is obtained with micro-nano holes 3 and electrode wire surfaces having a compound semiconductor material formed by metal and oxygen in the air adhered to it, and the zinc content of the copper-zinc alloy surface layer 2 is 62%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO and Sn + O2 → SnO2. The semiconductor material is specifically: a number of ZnO, CuO and SnO particles 4 with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the electrode wire surface.

[0102] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1400 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0103] The obtained electrode wire has a tensile strength of 1030 MPa and a conductivity of 24% IACS. The final product has a surface thickness of 20 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-25 μm and the depth is 0.2-45 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is preferably 0.1-20 μm and the depth is preferably 0.2-45 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 10 nm and a maximum size of 4000 nm.

[0104] Example 5

[0105] 1) Prepare a brass core material with a diameter of 1.1 mm and a zinc content of 37%;

[0106] 2) Electroplating a zinc-based surface layer on the surface of the brass core material 1 obtained in step 1), adding 18KG of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, an electroplating speed of 750m / min, a current of 900A, a voltage of 8V, and a surface layer thickness of 19μm;

[0107] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.85 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0108] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 230°C for 14 hours. It is then cooled in the furnace to below 100°C and removed from the furnace to obtain a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0109] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.56 mm.

[0110] 6) The semi-finished wire blank obtained from the second stretching is heat-treated in an air atmosphere in a furnace at a temperature of 440°C for 10 hours. After cooling in the furnace to below 150°C, the wire blank is obtained with micro-nano holes 3 and electrode wire surfaces having a compound semiconductor material formed by metal and oxygen in the air adhered to them, and the zinc content of the copper-zinc alloy surface layer 2 is 47%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO and 4Cu + O2 → 2Cu2O. The semiconductor material is specifically: a number of ZnO, CuO and Cu2O particles 4 with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the electrode wire surface.

[0111] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1000m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25mm.

[0112] The obtained electrode wire has a tensile strength of 950 MPa and a conductivity of 23% IACS. The final product has a surface thickness of 27 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-40 μm and the depth is 0.2-35 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.1-30 μm and the depth is 0.2-35 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 100 nm and a maximum size of 2000 nm.

[0113] Example 6

[0114] 1) Prepare a brass core material with a diameter of 1.2 mm and a zinc content of 43%;

[0115] 2) Electroplating a zinc-based surface layer on the surface of the brass core material 1 obtained in step 1), adding 28KG of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, an electroplating speed of 80m / min, a current of 1200A, a voltage of 16V, and a surface layer thickness of 30μm.

[0116] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.75 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0117] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 175℃ for 12 hours. It is then cooled in the furnace to below 100℃ before being removed from the furnace, resulting in a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0118] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.57mm.

[0119] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 450°C for 11 hours. After cooling in the furnace to below 150°C, the wire blank is obtained after heat treatment. The wire blank has a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes 3 and the electrode wire, and the zinc content of the copper-zinc alloy surface layer 2 is 85%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO. The semiconductor material is specifically: a number of ZnO particles 4 with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the surface of the electrode wire.

[0120] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1300 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0121] The obtained electrode wire has a tensile strength of 1100 MPa and a conductivity of 19% IACS. The final product has a surface thickness of 40 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.3-60 μm and the depth is 0.5-30 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.2-40 μm and the depth is 0.6-30 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 50 nm and a maximum size of 5000 nm.

[0122] Example 7

[0123] 1) Prepare a brass core material with a diameter of 1.0 mm and a zinc content of 35%;

[0124] 2) Electroplating a zinc-based surface layer onto the surface of the brass core material 1 obtained in step 1), adding trace element Ni such as nickel sulfate to the electroplating bath, wherein the concentration of trace element nickel is 60 g / L, so that the copper-zinc alloy surface layer contains trace elements copper, zinc and nickel to form a zinc-based composite surface layer; adding 25 kg of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, the electroplating speed is 450 m / min, the current is 1500 A, the voltage is 15 V, and the surface layer thickness is 12 μm;

[0125] 3) The wire blank obtained after electrodeposition is stretched to a diameter of 0.81 mm for the first time through a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0126] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 280℃ for 6 hours. It is then cooled in the furnace to below 100℃ before being removed from the furnace, resulting in a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0127] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.49 mm.

[0128] 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 425°C for 17 hours. After cooling in the furnace to below 150°C, the wire blank is obtained after heat treatment. The wire blank has a compound semiconductor material formed by metal and oxygen in the air adhering to the surface of the micro-nano holes 3 and the electrode wire, and the zinc content of the copper-zinc alloy surface layer 2 is 59%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO and 2Ni + O2 → 2NiO. The semiconductor material is specifically: a number of ZnO, CuO and NiO particles with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the surface of the electrode wire.

[0129] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1200 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0130] The obtained electrode wire has a tensile strength of 850 MPa and a conductivity of 24% IACS. The final product has a surface thickness of 17 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.1-30 μm and the depth is 0.2-20 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.1-23 μm and the depth is 0.2-19 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 10 nm and a maximum size of 5000 nm.

[0131] Example 8

[0132] 1) Prepare a brass core material with a diameter of 1.2 mm and a zinc content of 40%;

[0133] 2) Electroplating a zinc-based surface layer onto the surface of the brass core material 1 obtained in step 1), adding trace elements Ni (such as nickel sulfate) and Sn (such as tin sulfate) to the electroplating bath, wherein the concentration of trace element nickel is 100 g / L and the concentration of trace element tin is 100 g / L, so that the copper-zinc alloy surface layer contains trace elements copper, zinc, nickel and tin to form a zinc-based composite surface layer; adding 25 kg of 0# zinc blocks per ton of electrodeposition bath, with a zinc content of not less than 99.995%, the electroplating speed is 300 m / min, the current is 1600 A, the voltage is 13 V, and the surface layer thickness is 23 μm;

[0134] 3) The wire blank obtained after electrodeposition is first stretched to a diameter of 0.85 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material 1, and a dense zinc-based composite layer is obtained from the first stretching of the wire blank.

[0135] 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 205℃ for 12 hours. It is then cooled in the furnace to below 100℃ and removed from the furnace to obtain a copper-zinc alloy surface layer 2 with a gamma phase structure and a heat-treated wire blank with more uniform trace elements in the surface layer.

[0136] 5) The heat-treated wire blank is stretched a second time through a wire drawing die. Since the composite surface with gamma phase structure is relatively hard and brittle, the surface breaks after stretching and forms several cracks, thus obtaining a semi-finished wire blank including brass core material 1 and copper-zinc alloy surface layer 2 with micro-nano holes 3. Several irregular micro-nano holes 3 are arranged along the circumference of the electrode wire and along the length of the electrode wire. The diameter of the semi-finished wire blank is 0.57mm.

[0137] 6) The semi-finished wire blank obtained from the second stretching is heat-treated in an air atmosphere inside a furnace at a temperature of 445°C for 20 hours. After cooling in the furnace to below 150°C, the wire blank is obtained with micro-nano holes 3 and electrode wire surfaces having a compound semiconductor material formed by metal and oxygen in the air adhered to them, and the zinc content of the copper-zinc alloy surface layer 2 is 75%. The chemical reaction process in this embodiment is as follows: 2Zn + O2 → 2ZnO, 2Cu + O2 → 2CuO, 2Ni + O2 → 2NiO and Sn + O2 → SnO2; The semiconductor material is specifically: a number of ZnO, CuO, NiO and SnO2 particles 4 with semiconductor function are aggregated in the micro-nano holes 3 and adhered to the electrode wire surface.

[0138] 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 1400 m / min and then subjected to stress-relief annealing. The particles on the surface of the wire blank and between the surface cracks are deformed and redistributed to obtain an electrode wire with a diameter of 0.25 mm.

[0139] The obtained electrode wire has a tensile strength of 970 MPa and a conductivity of 23% IACS. The final product has a surface thickness of 35 μm; the width of each micro-nano hole 3 in the cross-section of the electrode wire is 0.4-45 μm and the depth is 0.2-26 μm; the length of each micro-nano hole 3 in the longitudinal section of the electrode wire is 0.3-36 μm and the depth is 0.2-28 μm; the semiconductor particles 4 are all irregularly shaped, with a minimum size of 30 nm and a maximum size of 5000 nm.

[0140] Comparison of proportions:

[0141] Comparative Example 1: 0.25mm brass wire purchased from the market.

[0142] Comparative Example 2: A 0.25mm galvanized wire purchased from the market, with a zinc coating.

[0143] Comparative Example 3: A 0.25mm gamma electrode wire purchased from the market, with a γ phase coating. This type of electrode wire is a commonly used gamma wire in the market.

[0144] Comparative Example 4: A 0.25mm high-speed coated wire purchased from the market, with a coating of β'+γ phase.

[0145] Comparative Example 5: 0.25mm speed-type electrode wire manufactured for patent 202111210891.X.

[0146] Comparative Example 6: 0.25mm precision electrode wire manufactured for patent 202010509917.X.

[0147] The tested wire EDM machine was a Sodick ALN400 series. The material being processed was tungsten steel. The workpiece thickness was 60mm, and the shape was a 10*10mm square. 0.25mm electrode wire was used. The process involved cutting one part and repairing two parts, followed by surface finishing.

[0148] Compared with the workpieces processed by the electrode wires of Comparative Examples 1-6, the workpieces processed using the electrode wires of Examples 1-8 in Table 1 show that the composite electrode wire of the present invention has significant advantages in cutting speed, processing accuracy and workpiece surface quality (line marks). That is, compared with Comparative Example 1, the cutting speed of the electrode wire of the present invention is increased by 30.58% to 50.41%, the processed workpieces have no lines, and the surface quality is better.

[0149] Table 1 shows the processing test data of the embodiments and comparative examples of the present invention:

[0150]

[0151] It's easy to understand that μm in the table refers to micrometers. mm in the table refers to millimeters, which are units of length; the smaller the value, the higher the processing precision.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite electrode wire for wire cutting of cemented carbide materials, comprising a brass core with a zinc content of 20%-43% and a copper-zinc alloy surface layer with a zinc content of 40%-85%; characterized in that: The copper-zinc alloy surface has irregularly distributed micro- and nano-pores, each extending to the surface of the electrode wire; semiconductor-functional particles are adhered to the micro- and nano-pores and the surface of the electrode wire; the semiconductor-functional particles include zinc oxide, and also include one or more of copper oxide and cuprous oxide.

2. The composite electrode wire for wire cutting cemented carbide materials according to claim 1, characterized in that: The semiconductor particles are all irregularly shaped, with the smallest size of a single particle ranging from 1 to 4700 nm and the largest size ranging from 10 to 5000 nm.

3. The composite electrode wire for wire cutting cemented carbide materials according to claim 1, characterized in that: Semiconductor-functional particles include ZnO, as well as one or more of CuO, NiO, Cu2O, and SnO2.

4. The composite electrode wire for wire cutting cemented carbide materials according to claim 1, characterized in that: The radial depth dimension of the micro-nano aperture is greater than the circumferential width dimension; or the radial depth dimension of the micro-nano aperture is greater than the axial length dimension; or the radial depth dimension of the micro-nano aperture is greater than both the circumferential width dimension and the axial length dimension; or the radial depth dimension of the micro-nano aperture is less than the circumferential width dimension; or the radial depth dimension of the micro-nano aperture is less than both the circumferential width dimension and the axial length dimension.

5. A composite electrode wire for wire cutting cemented carbide materials according to claim 1, characterized in that: The thickness of the copper-zinc alloy surface layer is 2-40 μm; the width of a single micro-nano hole on the cross-section of the electrode wire is 0.1-60 μm and the depth is 0.2-45 μm; the length of a single micro-nano hole on the longitudinal section of the electrode wire is 0.1-40 μm and the depth is 0.2-45 μm.

6. The composite electrode wire for wire cutting cemented carbide materials according to claim 1, characterized in that: Several irregular micro- and nano-pores are arranged along the circumference of the electrode wire and along the length of the electrode wire; there are several semiconductor-functional particles adhering to the micro- and nano-pores and the surface of the electrode wire.

7. A method for preparing a composite electrode wire for wire cutting cemented carbide materials as described in claim 1, characterized in that, The process includes the following steps: 1) Prepare brass core material with a diameter of 0.7-1.5 mm and a zinc content in the range of 20% to 43%; 2) Electroplating a zinc-based surface layer onto the brass core material obtained in step 1), with an electroplating speed of 300-800 m / min, a current of 500-2000 A, a voltage of 5-20 V, and a surface layer thickness of 1-30 μm; 3) The wire blank obtained after electroplating is first stretched to a diameter of 0.5-1.0 mm using a wire drawing die, so that the composite surface layer is evenly distributed on the surface of the brass core material, and a dense wire blank with a zinc-based composite layer is obtained from the first stretching. 4) The wire blank obtained from the first stretching is subjected to heat treatment at a temperature of 150-300℃ for 0.5-20h. It is then cooled in the furnace to below 100℃ and removed from the furnace to obtain a heat-treated wire blank with a copper-zinc alloy surface layer having a gamma phase structure. 5) The heat-treated wire blank is stretched a second time through a wire drawing die to obtain a semi-finished wire blank including a brass core and a copper-zinc alloy surface layer with micro-nano holes. The diameter of the semi-finished wire blank is 0.35-0.85mm. 6) The semi-finished wire blank obtained from the second stretching above is heat-treated in an air atmosphere in a furnace at a temperature of 300-500℃ for 2-30 hours. After cooling in the furnace to below 150℃, the wire blank is obtained with a compound semiconductor material formed by metal and oxygen in the air adhering to the micro-nano pores and the surface of the electrode wire. The semiconductor material includes at least zinc oxide and the zinc content of the copper-zinc alloy surface layer is 40%-85%. 7) The wire blank obtained in step 6) is stretched for the third time at a stretching speed of 500-2000 m / min and then subjected to stress-relief annealing to obtain an electrode wire finished product with a diameter of 0.15-0.30 mm.

8. The preparation method according to claim 7, characterized in that: In step 2), 1-30 kg of 0# zinc blocks are added to each ton of electrodeposition bath solution. The zinc content is not less than 99.995%. The brass core material is used as the cathode and the zinc block is used as the anode. After the current is applied, the zinc ions on the zinc block lose electrons under the action of the current and dissolve into the electrolyte to form zinc ions. These zinc ions move to the surface of the brass core material under the action of the electric field and gain electrons on the surface of the brass core material, and are reduced to metallic zinc, thereby forming a zinc plating layer on the surface of the brass core material.

9. The preparation method according to claim 7, characterized in that: Step 2) Add one or two trace elements Ni and Sn to the electroplating bath, specifically nickel sulfate and / or tin sulfate, with the concentration of each trace element being 1-100 g / L, so that the zinc-based surface layer also contains trace elements Ni and / or Sn to form a zinc-based composite surface layer; Step 6) The semiconductor material also includes copper oxide and / or cuprous oxide and / or nickel oxide and / or tin oxide.

10. The preparation method according to claim 9, characterized in that: In step 6), the chemical reaction process is as follows: 2Zn + O2 → 2ZnO, or / and 2Cu + O2 → 2CuO, or / and 4Cu + O2 → 2Cu2O, or / and 2Ni + O2 → 2NiO, or / and Sn + O2 → SnO2.

11. The preparation method according to claim 7, characterized in that: The tensile strength of the obtained electrode wire products is 750-1100MPa, and the conductivity is 19%-28%IACS.

Images