A coated electrode wire and a method of making the same

Abstract

This invention provides a coated electrode wire and its preparation method, comprising: (1) surface-treating a brass busbar, then hot-dip galvanizing it, followed by sizing using a die and removal from the hot-dip galvanizing solution; (2) subjecting the hot-dip galvanized wire to online diffusion treatment; and (3) stretching and annealing the diffusion-treated wire to obtain the coated electrode wire. This invention uses hot-dip galvanizing instead of electroplating, avoiding the use of cyanide and making production more environmentally friendly. This invention can achieve stable galvanizing of both fine and coarse-gauge busbars and obtain a thicker diffusion alloy layer. Furthermore, this invention can precisely control the coating thickness after hot-dip galvanizing, reduce oxidation in the hot-dip galvanizing solution, and enable multi-wire parallel production of electrode wires. The resulting coated electrode wire has an ideal thickness ratio of β' phase or β'+γ phase copper-zinc alloy diffusion layer to zinc layer, exhibiting excellent electrical discharge machining performance.

Description

Technical Field

[0001] This invention relates to the field of wire electrical discharge machining, specifically to a coated electrode wire and its preparation method. Background Technology

[0002] Wire cut electrical discharge machining (WEDM) works by using a continuously moving fine metal wire as an electrode to remove metal from the workpiece through pulsed spark discharge. In WEDM, the workpiece is connected to the positive terminal of a pulse power supply, while the electrode wire is connected to the negative terminal as a tool electrode. The pulse power supply provides the machining energy, and a specialized wire cutting fluid is used to remove debris generated during the process. When energized, a spark is generated between the workpiece and the electrode wire under the influence of a strong electric field. The instantaneous temperature can reach 10,000 degrees Celsius, causing localized melting and vaporization of the metal. The vaporized working fluid and workpiece material expand rapidly and instantly. Under the combined effect of this thermal expansion and the flushing action of the working fluid, the molten and vaporized workpiece material is ejected from the discharge gap, completing one spark discharge cycle.

[0003] To improve the precision of wire EDM, a type of precision wire EDM electrode wire has been developed and applied in recent years. Wire EDM electrode wires have undergone several generations of technological advancements. Currently, coated wire is the highest-grade precision electrode cutting wire. Coated wire is a composite wire, meaning its interior is copper or ordinary brass, and its surface is coated with a high-zinc alloy layer of a certain thickness (i.e., an alloy layer with high zinc content) through a special process. Utilizing the properties of the high-zinc alloy, it achieves higher vaporization pressure, thereby helping to increase processing speed. Depending on the composition of the high-zinc alloy coating, coated wire can be divided into γ-coated wire, β-coated wire, etc.

[0004] The existing production methods for coating lines mainly employ electroplating, but this process presents several problems: First, the electroplating process requires the use of highly toxic cyanide, posing significant environmental risks. Second, it can only electroplat pure zinc, making it difficult to adjust the zinc layer composition to further optimize coating performance. Third, it is difficult to plate thicker zinc layers. Fourth, due to the long and complex electroplating production line, electroplating needs to be completed when the busbar is of relatively large specifications. Currently, electroplating is generally carried out when the busbar diameter is around 1.2 mm. When producing extremely fine electrode wires, there are still many steps required after electroplating, making it difficult to control product quality.

[0005] The prior art discloses a method for preparing electrode wires by controlling the coating film through a blowing method. This method has the following technical problems: First, the wire diameter of the busbar cannot be too thin, otherwise the wire is prone to shaking or even breaking. Second, the blowing device is large, and the distance between the two wires is large, which is not conducive to multi-line production and results in low production efficiency. Third, to ensure the coating thickness, a large airflow must be used for blowing, but this large airflow will cause strong agitation of the zinc liquid, resulting in splashing and damage to the zinc oxide film, leading to oxidation of the zinc liquid. Furthermore, inert gases must be used, increasing production costs. Fourth, to ensure that the zinc liquid continues to adhere to the copper wire for a longer period after it leaves the zinc bath, the fluidity of the zinc liquid is required to be high, necessitating a higher temperature in the zinc bath. However, excessively high temperatures will intensify zinc oxidation and accelerate the diffusion of copper into the zinc liquid, causing a rapid increase in the copper atom concentration in the zinc liquid and increasing the frequency of zinc liquid replacement. Fifth, it is difficult to coat larger busbars, especially when the diameter of the busbar is greater than 2.0 mm, resulting in a thinner copper-zinc alloy thermal diffusion layer. Summary of the Invention

[0006] This invention provides a coated electrode wire and its preparation method. This method abandons the electroplating and zinc plating process and solves the problems in the prior art where the brass busbar is too small or too large to be plated, and the diffusion alloy layer formed by plating is too thin.

[0007] In a first aspect, the present invention provides a method for preparing coated electrode wires, comprising the following steps: S1, after surface treatment, the brass busbar is galvanized by hot-dip galvanizing, and then sized by a die. The diameter of the eye hole of the die is 10μm-40μm larger than the diameter of the brass busbar. S2, the galvanized wire undergoes online diffusion treatment in the annealing furnace tube, with a diffusion temperature of 240℃-450℃; S3, the wire after diffusion treatment is stretched and annealed to obtain coated electrode wire.

[0008] In one optional embodiment, the diameter of the brass busbar is 0.1mm-3.0mm; In one optional embodiment, the hot-dip plating solution used is selected from one or more of liquid pure zinc, liquid zinc-aluminum alloy, and liquid zinc-magnesium alloy; the temperature conditions for hot-dip plating are 410℃-450℃.

[0009] In one optional embodiment, the mass percentage of aluminum in the liquid zinc-aluminum alloy is 5.0 wt%-6.0 wt%; and the mass percentage of magnesium in the zinc-magnesium alloy is 1.0 wt%-2.5 wt%.

[0010] In one optional embodiment, the thickness of the coating after hot-dip galvanizing is 1.7μm-30μm.

[0011] In one optional embodiment, the moving speed of the brass busbar during hot-dip plating is 20m / min-400m / min.

[0012] In one optional embodiment, the surface treatment described in S1 includes: after alkali washing, acid washing, and water washing of the brass busbar, applying flux to the brass busbar.

[0013] Furthermore, after galvanizing, the multiple brass busbars are sized using different eye molds.

[0014] In one optional embodiment, the annealing temperature of the annealing process in S3 is 320℃-400℃.

[0015] Secondly, the present invention also provides a coated electrode wire prepared by the above method, comprising a brass busbar and a coating layer covering the brass busbar, wherein the coating layer comprises a diffusion alloy layer and a zinc layer sequentially covering the brass busbar, and the thickness of the diffusion alloy layer is greater than the thickness of the zinc layer.

[0016] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing coated electrode wires. A specific brass busbar is selected, and after hot-dip galvanizing, die sizing, online diffusion treatment, stretching, and annealing, a coated electrode wire is obtained. Electroplating can only deposit a relatively thin zinc layer; otherwise, production efficiency is low and costs are significantly increased. This invention employs a hot-dip galvanizing process, which can efficiently complete the coating of thicker layers. When using thicker brass busbars (e.g., Ф3.0mm) for hot-dip galvanizing of thicker layers, production efficiency can be greatly improved. This invention uses die sizing to hot-dip galvanize very fine brass busbars (e.g., Ф0.1mm), which is beneficial for further production of ultra-fine electrode wires such as Ф0.05mm. In addition, die sizing can precisely control the coating thickness. When using die sizing, the surface of the hot-dip solution is stable, which can effectively reduce the oxidation of the hot-dip solution. This invention uses online diffusion treatment, where zinc enters the brass busbar inside the electrode wire, efficiently forming a thick diffusion alloy layer on its surface.

[0017] 2. This invention provides a method for preparing coated electrode wires. The method employs a hot-dip galvanizing process, which significantly enhances the environmental friendliness of the production process. Hot-dip galvanizing is a liquid-solid diffusion process, inherently possessing diffusion behavior, which greatly reduces subsequent diffusion time and energy consumption. The waste zinc generated after hot-dip galvanizing can be directly remelted to produce brass for use in the production of brass busbars, generating no solid or hazardous waste. Furthermore, this invention uses a die-sizing method. Due to the small size of the dies, by installing multiple dies in the hot-dip galvanizing tank, multiple brass busbars can be sized using different dies after galvanizing, enabling multi-line production.

[0018] 3. This invention provides a coated electrode wire, comprising a brass busbar and a coating layer covering the brass busbar. The coating layer includes a diffusion alloy layer and a zinc layer sequentially coated on the brass busbar, with the thickness of the diffusion alloy layer being greater than the thickness of the zinc layer. The brass busbar has a high copper content, resulting in excellent conductivity and superior toughness. The coating layer has a high zinc content and a low vaporization temperature, leading to good vaporization rinsing during discharge. Furthermore, the thickness of the diffusion alloy layer in the coating layer is greater than that of the zinc layer, ensuring uniform consumption of the coating during electrical discharge machining. Using the coated electrode wire of this invention for wire EDM can significantly increase the discharge frequency, resulting in a substantial increase in processing speed. The coated electrode wire of this invention provides a stable vaporization rinsing effect. Detailed Implementation

[0019] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0020] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0021] The brass busbar used in this invention has a Cu content of 60.5wt%-71.5wt%, with the balance being zinc, and other impurities and their content ranges permitted by relevant national standards. The brass busbar undergoes consecutive alkaline washing, acid washing, and water washing, followed by the application of flux. Finally, it enters a zinc bath containing hot-dip galvanizing solution. Guide rollers within the zinc bath are immersed in the solution. The brass busbar enters the solution from one end and exits through a die at the other end via the guide rollers. The die is positioned at the surface of the hot-dip galvanizing solution. After exiting the solution, the hot-dip galvanized wire is cooled by cold air and then wound up, completing the hot-dip galvanizing process of the brass busbar.

[0022] The purpose of the eye mold is to control the thickness of the coating after hot-dip galvanizing. The diameter of the eye hole of the eye mold is 10μm-40μm larger than the diameter of the busbar, so as to control the thickness of the coating after hot-dip galvanizing to be 1.7μm-30μm. Generally, the thinner the wire, the thinner the coating, and vice versa.

[0023] When the hot-dip immersion liquid is liquid pure zinc, the temperature of the hot-dip immersion liquid in the zinc bath is 20°C-50°C above the melting point of pure zinc; when the hot-dip immersion liquid is liquid zinc-aluminum alloy, the temperature of the hot-dip immersion liquid in the zinc bath is 20°C-50°C above the melting point of zinc-aluminum alloy; when the hot-dip immersion liquid is liquid zinc-magnesium alloy, the temperature of the hot-dip immersion liquid in the zinc bath is 20°C-50°C above the melting point of zinc-magnesium alloy.

[0024] Online diffusion treatment is performed on hot-dip galvanized wires to diffuse zinc or zinc alloys in the coating into the surface of brass wires. By controlling the diffusion temperature, a β' phase copper-zinc alloy layer or a β'+γ phase copper-zinc alloy layer can be formed on the surface of the brass busbar.

[0025] The diffusion-treated wire is further subjected to multiple stretching and forming processes to gradually bring it up to the specifications of the final product.

[0026] The formed wire undergoes annealing to relieve stress and soften it. During annealing, zinc atoms and other atoms in the zinc alloy further diffuse, ultimately forming a composite wire with an innermost brass busbar, a middle diffusion alloy layer, and an outermost zinc layer, resulting in a high-performance coated electrode wire. Annealing is preferably performed in a tubular annealing furnace to improve production efficiency. For larger product sizes, continuous drawing and annealing equipment can also be used.

[0027] The brass busbar used in this invention conforms to the national standard GB / T 5231-2022 "Grades and Chemical Composition of Processed Copper and Copper Alloys", wherein: H62 brass: Cu content 60.5–63.5 wt%, Fe a Content 0.15wt%, Pb content 0.08wt%, balance Zn; H65 brass: Cu content 63.5–68.0 wt%, Fe a Content 0.07wt%, Pb content 0.09wt%, balance Zn; H70 brass: Cu content 68.5–71.5 wt%, Fe a The content is 0.10 wt%, the Pb content is 0.03 wt%, and the balance is Zn.

[0028] The busbar conditions H02 (1 / 2 hard) and H04 (hard) shall comply with the provisions of GB / T 21652-2017 "Copper and Copper Alloy Wires".

[0029] The pure zinc ingots conform to the Zn99.99 or Zn99.995 grade in GB / T 470-2008.

[0030] The selection of the eye mold is related to the diameter of the brass busbar. When the diameter of the brass busbar is ≥0.30mm, a domestic high-crystal mold is selected, and the roughness (Ra) of the sizing area of ​​the domestic high-crystal mold is ≤0.02μm - 0.05μm. When the diameter of the brass busbar is <0.30mm, a natural diamond mold is selected, and the roughness (Ra) of the sizing area of ​​the natural diamond mold is ≤0.01μm.

[0031] The inert gas is nitrogen or argon, with a purity ≥99.99% (volume fraction) and an oxygen content ≤50ppm.

[0032] The flux is a lead-free, environmentally friendly flux branded MODICO, manufactured by Yunxin Electronic Materials (Shandong) Co., Ltd.

[0033] The β'+γ phase copper-zinc alloy layer is a copper-zinc alloy layer containing both β' and γ phases.

[0034] In this invention, "Ф" is the twenty-first Greek letter. In the field of engineering, "Ф" represents the diameter of cylindrical materials and equipment.

[0035] Example 1 This embodiment provides a method for preparing a coated electrode wire with a diameter of 0.25mm, which includes the following steps: S1 provides brass busbars with a diameter of Ф1.2mm, grade H62, and temper H02.

[0036] S2. The brass busbar is hot-dip galvanized to a thickness of 12 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. Zinc ingots of grade Zn99.99 or Zn99.995, as specified in national standard GB / T470-2008, are placed in the zinc bath. The temperature of the hot-dip solution in the zinc bath is 450℃, and the moving speed of the brass busbar during hot-dip galvanizing is 50 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a mortise and tenon joint with a hole size of Ф1.21 mm.

[0037] S3 involves online diffusion treatment of the hot-dip galvanized wire. The galvanized wire is placed in an annealing furnace tube under inert gas protection for diffusion treatment at a diffusion temperature of 350℃. The furnace tube is 6m long, and the wire moves at a speed of 50m / min within the furnace tube. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β' phase copper-zinc alloy layer.

[0038] S4. The diffusion-treated wire is subjected to multiple small-drawing processes to produce a wire with a diameter of Ф0.25mm.

[0039] S5 is a 0.25mm diameter wire formed by S4. It is annealed in a tubular annealing furnace at a temperature of 380℃. The length of the annealing furnace tube is 5m and the wire moving speed is 100m / min. This process is designed to eliminate stress in the wire and soften it to produce a high-performance coated electrode wire.

[0040] Example 2 This embodiment provides a method for preparing a coated electrode wire with a diameter of 0.1 mm, which includes the following steps: S1 provides brass busbars with a diameter of Ф0.60mm, grade H65, and temper H04.

[0041] S2. The brass busbar is hot-dip galvanized to a thickness of 11 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. The zinc bath contains zinc ingots of grade Zn99.99 or Zn99.995 as specified in national standard GB / T470-2008. The temperature of the hot-dip solution in the zinc bath is 445℃, and the moving speed of the brass busbar during hot-dip galvanizing is 100 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a 0.62 mm eyelet.

[0042] S3 involves online diffusion treatment of the hot-dip galvanized wire. The galvanized wire is placed in an annealing furnace tube under inert gas protection for diffusion treatment at a diffusion temperature of 320℃. The furnace tube is 6m long, and the wire moves at a speed of 100m / min within the furnace tube. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β'+γ phase copper-zinc alloy layer.

[0043] S4. The diffusion-treated wire is subjected to multiple small-drawing processes to produce a wire with a diameter of Ф0.1mm.

[0044] S5 is a 0.1mm diameter wire formed by S4 that is annealed in a tubular annealing furnace at a temperature of 350℃. The furnace tube is 5m long and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a high-performance coated electrode wire product.

[0045] Example 3 This embodiment provides a method for preparing a coated electrode wire with a diameter of 0.05 mm, which includes the following steps: S1 provides brass busbars with a wire diameter of Ф0.1mm, grade H70, and temper H04.

[0046] S2. The brass busbar is hot-dip galvanized to a thickness of 1.7 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. The zinc bath contains zinc-aluminum ingots with an aluminum content of 6 wt%. The temperature of the hot-dip solution in the zinc bath is 420℃, and the moving speed of the brass busbar during hot-dip galvanizing is 400 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a ferrule with an eyelet size of Ф0.11 mm.

[0047] S3 involves online diffusion treatment of the hot-dip galvanized wire. The galvanized wire is placed in an annealing furnace tube under inert gas protection for diffusion treatment at a diffusion temperature of 240℃. The furnace tube is 6m long, and the wire moves at a speed of 400m / min within the furnace tube. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β'+γ phase copper-zinc alloy layer.

[0048] S4. The diffusion-treated wire is subjected to multiple micro-drawing processes to produce a wire with a diameter of Ф0.05mm.

[0049] S5 is a 0.05mm diameter wire formed by S4 that is annealed in a tubular annealing furnace at a temperature of 320℃. The furnace tube is 5m long and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a high-performance coated electrode wire product.

[0050] Example 4 This embodiment provides a method for preparing a coated electrode wire with a diameter of 0.30 mm, which includes the following steps: S1 provides brass busbars with a diameter of Ф3.0mm, grade H62, and temper H02.

[0051] S2. The brass busbar is hot-dip galvanized to a thickness of 30 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. The zinc bath contains zinc ingots of grade Zn99.99 or Zn99.995 as specified in national standard GB / T470-2008. The temperature of the hot-dip solution in the zinc bath is 450℃, and the moving speed of the brass busbar during hot-dip galvanizing is 20 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a 3.04 mm eyelet.

[0052] S3 involves online diffusion treatment of the hot-dip galvanized wire. The galvanized wire is placed in an annealing furnace tube under inert gas protection for diffusion treatment at a diffusion temperature of 450℃. The furnace tube is 6m long, and the wire moves at a speed of 20m / min within the furnace tube. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β' phase copper-zinc alloy layer.

[0053] S4. The diffusion-treated wire is subjected to multiple small-drawing processes to produce a wire with a diameter of Ф0.30mm.

[0054] S5 is a 0.30mm diameter wire formed by S4 that is annealed in a tubular annealing furnace at a temperature of 400℃. The furnace tube is 5m long and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a high-performance coated electrode wire product.

[0055] Example 5 This embodiment provides a method for preparing a coated electrode wire with a diameter of 0.05 mm, which includes the following steps: S1 provides brass busbars with a wire diameter of Ф0.1mm, grade H70, and temper H04.

[0056] S2. The brass busbar is hot-dip galvanized to a thickness of 1.7 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. The zinc bath contains zinc-magnesium ingots with a magnesium content of 2.5 wt%. The temperature of the hot-dip solution in the zinc bath is 410℃, and the moving speed of the brass busbar during hot-dip galvanizing is 400 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a ferrule with an eyelet size of Ф0.11 mm.

[0057] S3 involves online diffusion treatment of the hot-dip galvanized wire. The galvanized wire is placed in an annealing furnace tube under inert gas protection for diffusion treatment at a diffusion temperature of 240℃. The furnace tube is 6m long, and the wire moves at a speed of 400m / min within the furnace tube. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β'+γ phase copper-zinc alloy layer.

[0058] S4. The diffusion-treated wire is subjected to multiple micro-drawing processes to produce a wire with a diameter of Ф0.05mm.

[0059] S5 is a 0.05mm diameter wire formed by S4 that is annealed in a tubular annealing furnace at a temperature of 320℃. The furnace tube is 5m long and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a high-performance coated electrode wire product.

[0060] Comparative Example 1 The electrode wire used in this comparative example is a 0.25mm galvanized electrode wire purchased from the market and prepared using an electroplating zinc plating process. Its coating is a pure zinc coating. The manufacturer is Ningbo Boway Alloy Precision Wire Co., Ltd., and the product name is BPcut T.

[0061] Comparative Example 2 The difference between this comparative example and Example 1 is that the electroplating zinc plating process is used instead of the hot-dip galvanizing zinc plating process.

[0062] This comparative example provides an electrode wire with a diameter of Ф0.25mm, the composition of which and the specific preparation steps are as follows: S1 provides brass busbars with a diameter of Ф1.2mm, grade H62, and temper H02.

[0063] S2, the brass busbar is electroplated with zinc, the coating is a pure zinc coating, and the coating thickness is 12μm.

[0064] S3. The electroplated galvanized wire undergoes a diffusion treatment. The coiled wire, after electroplating and galvanizing, is placed in an annealing furnace tube under inert gas protection for diffusion treatment. The diffusion temperature is 350℃, the furnace tube length is 6m, and the wire's moving speed within the annealing furnace tube is 50m / min. After diffusion treatment, the wire is cooled by cold air and then wound up. The diffusion alloy layer of the wire is a β' phase copper-zinc alloy layer.

[0065] S4. The diffusion-treated wire is subjected to multiple small-drawing processes to produce a wire with a diameter of Ф0.25mm.

[0066] S5 involves annealing the 0.25mm diameter wire formed in S4 using a tubular annealing furnace at a temperature of 380℃. The furnace tube is 5m long, and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a coated electrode wire product.

[0067] Comparative Example 3 The difference between this comparative example and Example 4 is that it did not undergo online diffusion treatment.

[0068] This comparative example provides a coated electrode wire with a diameter of Ф0.3mm, the composition of which and the specific preparation steps are as follows: S1 provides brass busbars with a diameter of Ф3.0mm, grade H62, and temper H02.

[0069] S2. The brass busbar is hot-dip galvanized to a thickness of 30 μm. Before hot-dip galvanizing, the brass busbar is sequentially passed through an alkaline washing tank, an acid washing tank, a water washing tank, and a flux tank before entering the zinc bath. The zinc bath contains zinc ingots of grade Zn99.99 or Zn99.995 as specified in national standard GB / T470-2008. The temperature of the hot-dip solution in the zinc bath is 450℃, and the moving speed of the brass busbar during hot-dip galvanizing is 20 m / min. After hot-dip galvanizing, the brass busbar exits the zinc bath through a 3.04 mm eyelet.

[0070] S3 involves cooling the hot-dip galvanized wire with cold air before winding it up. The diffusion alloy layer of the wire is a β'+γ phase copper-zinc alloy layer.

[0071] S4 involves multiple small-scale drawing processes on the cooled wire to produce a wire with a diameter of Ф0.30mm.

[0072] S5 is a 0.30mm diameter wire formed by S4 that is annealed in a tubular annealing furnace at a temperature of 400℃. The furnace tube is 5m long and the wire moves at a speed of 100m / min to eliminate stress and soften the wire, resulting in a high-performance coated electrode wire product.

[0073] Test case The coated electrode wires in each embodiment and comparative example were tested for wire diameter, wire coating thickness, wire tensile strength, wire elongation, and conductivity. The specific testing methods are as follows: The diameter and permissible deviation of the wire shall be tested in accordance with GB / T 26303.2-2010. The zinc coating thickness and diffusion alloy coating thickness of the wire shall be tested in accordance with GB / T 6462-2025, and the coating thickness shall be equal to the sum of the diffusion alloy coating thickness and the zinc coating thickness. For wires with a diameter not greater than 0.25 mm, the tensile strength and elongation shall be tested in accordance with GB / T 10573-2020; for wires with a diameter greater than 0.25 mm, the tensile strength and elongation shall be tested in accordance with GB / T 228.1-2021. The conductivity of the wire shall be tested in accordance with GB / T 351-2019.

[0074] The performance test results of the coated electrode wires prepared in the above embodiments and comparative examples are shown in the table below: Table 1 Performance parameters of the coated electrode wire prepared in this invention

[0075] As can be seen from the test data in Table 1, the coated electrode wires prepared by the method of the present invention in Examples 1-5 show significant differences in microstructure, mechanical properties, and electrical properties compared with the coated electrode wires prepared by the conventional electroplating zinc process in Comparative Examples 1-2 and the coated electrode wires prepared by the non-online diffusion process in Comparative Example 3. Specifically: The hot-dip galvanizing, die sizing, and online diffusion processes employed in this invention, compared to traditional electroplating galvanizing, can form a denser and more uniform diffusion alloy layer, reducing interfacial resistance and coating porosity, thereby significantly improving the conductivity of the coated electrode wire. It is noteworthy that even in Comparative Example 3, which did not undergo online diffusion treatment, the wire conductivity was lower than that of Example 4, which did undergo online diffusion treatment, indicating that online diffusion treatment plays a crucial role in optimizing the bonding between the coating and the core material and improving conductivity.

[0076] As can be seen from the coating thickness data, in Examples 1-5, the ratio of the diffusion alloy layer thickness to the zinc layer thickness is generally greater than or close to 1:1, indicating that the online diffusion treatment effectively promotes the diffusion of zinc atoms into the core material, forming a relatively thick functional diffusion alloy layer. In contrast, although Comparative Example 3, which did not undergo online diffusion treatment, experienced natural cooling after hot-dip plating, its zinc layer thickness was significantly greater than that of the diffusion alloy layer, and its conductivity and tensile strength were slightly lower than those of Example 4. This shows that natural cooling after hot-dip plating alone cannot achieve sufficient solid-state diffusion; a specialized online diffusion treatment is required to obtain the ideal alloy phase composition and thickness ratio, thereby ensuring uniform consumption of the coating and stable vaporization rinsing effect during electrical discharge machining.

[0077] Data from Examples 2, 3, and 5 demonstrate that the eye-die sizing technology employed in this invention can stably hot-dip plate extremely fine brass busbars, producing a uniform coating with high tensile strength and elongation of the final product. In contrast, the blow-dip method, due to the risk of wire swaying or even breakage caused by airflow impact, makes it difficult to stably produce such ultra-fine products. This fully verifies the adaptability and process stability of the method of this invention for fine-gauge busbars.

[0078] In summary, this invention, by replacing electroplating with hot-dip galvanizing and combining it with eyelet sizing and online diffusion treatment, not only achieves environmentally friendly production but also achieves significant technical advantages over existing technologies in terms of conductivity, controllability of coating structure, and fine wire preparation capabilities.

[0079] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a coated electrode wire, characterized in that, Includes the following steps: S1, after surface treatment, the brass busbar is galvanized by hot-dip galvanizing, and then sized by a die. The diameter of the eye hole of the die is 10μm-40μm larger than the diameter of the brass busbar. S2, the galvanized wire undergoes online diffusion treatment in the annealing furnace tube, with a diffusion temperature of 240℃-450℃; S3, the wire after diffusion treatment is stretched and annealed to obtain coated electrode wire.

2. The method according to claim 1, characterized in that, The diameter of the brass busbar is 0.1mm-3.0mm.

3. The method according to claim 1, characterized in that, The hot-dip galvanizing solution used is selected from one or more of liquid pure zinc, liquid zinc-aluminum alloy, and liquid zinc-magnesium alloy; And / or, the temperature conditions for the hot-dip galvanizing are 410℃-450℃.

4. The method according to claim 3, characterized in that, The mass percentage of aluminum in the liquid zinc-aluminum alloy is 5.0 wt%-6.0 wt%. And / or, the mass percentage of magnesium in the liquid zinc-magnesium alloy is 1.0 wt%-2.5 wt%.

5. The method according to claim 4, characterized in that, The thickness of the coating after hot-dip galvanizing is 1.7μm-30μm.

6. The method according to claim 5, characterized in that, The moving speed of the brass busbar during hot-dip galvanizing is 20m / min-400m / min.

7. The method according to any one of claims 1-6, characterized in that, In step S1, the surface treatment includes: after alkali washing, acid washing, and water washing of the brass busbar, applying flux to the brass busbar.

8. The method according to any one of claims 1-6, characterized in that, In step S1, multiple brass busbars are galvanized and then sized using different eye molds.

9. The method according to any one of claims 1-6, characterized in that, In step S3, the annealing temperature for the annealing process is 320℃-400℃.

10. A coated electrode wire, characterized in that, The electrode wire prepared by the method according to any one of claims 1-9 includes a brass busbar and a coating layer covering the brass busbar. The coating layer includes a diffusion alloy layer and a zinc layer sequentially covering the brass busbar, and the thickness of the diffusion alloy layer is greater than the thickness of the zinc layer.

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