Method for producing copper wire rod for multi-head wire drawing machine

Abstract

The application discloses a copper wire blank production method for a multi-head wire drawing machine, relates to the technical field of copper wire blanks, and comprises the following steps: selecting raw materials, equipment inspection and initial charging, preheating of a furnace system, copper material heating, melting and charging, copper liquid scum removal, copper liquid oxygen content control, continuous casting, pre-rolled piece trimming, continuous rolling, copper wire blank cooling, copper wire blank drying and copper wire blank protection, so as to obtain the copper wire blank. The copper wire blank obtained by the method effectively reduces the proportion of defects such as inclusions, cracks and pores in the obtained copper wire blank, the breaking rate of the copper wire blank in the multi-head wire drawing machine is obviously reduced, and the obtained copper wire blank is especially suitable for the production of the multi-head wire drawing machine.

Description

Technical Field

[0001] This application relates to the field of copper wire blank technology, and in particular to a method for producing copper wire blanks for multi-head wire drawing machines. Background Technology

[0002] Multi-head wire drawing machines, compared to single-head machines, have multiple drawing heads. A typical multi-head machine operates by drawing seven wires per unit, and can be configured into 7-head, 14-head, 21-head, and 28-head machines, drawing 7, 14, 21, or 28 copper wires at a time, and then feeding the finished wires onto one or two reels. Alternatively, depending on the cable structure requirements, machines can be configured by drawing eight wires per unit, resulting in 8-head, 16-head, 24-head, and 32-head machines. The number of drawing passes can be arbitrarily selected between 5 and 30, depending on the stranding requirements of the next process.

[0003] The use of multi-head wire drawing machines greatly improves wire drawing production efficiency. For example, a 16-head multi-head wire drawing machine can draw up to 16 copper wires simultaneously, which is equivalent to the production efficiency of 16 single-head wire drawing machines. That is, under stable production conditions, one 16-head multi-head wire drawing machine is equivalent to the production efficiency of 16 single-head wire drawing machines.

[0004] In actual production, the copper wire blanks produced by existing methods often exhibit significant fluctuations in performance indicators, poor elongation, high breakage rate, rough surface quality, high resistivity, and poor tensile and torsional properties. This makes them highly susceptible to breakage during multi-head wire drawing. A break in one end can interfere with other ends, causing them to break as well. The die-threading time after a breakage depends on the location of the break. If the breakage occurs at the annealing machine or the end of the wire drawing machine, the die-threading operation is relatively simple and quick. However, if the breakage occurs at the front of the wire drawing machine, i.e., the copper wire blank entry point, taking a 24-head wire drawing machine as an example, it requires threading 24 x 25 dies, or 600 dies. With an average threading time of 8 minutes per die, the total threading time would be 4800 minutes. Even with continuous threading operations, it would take 3.3 days to complete the entire wire drawing machine's threading process.

[0005] The more heads a multi-head wire drawing machine produces, the longer the die-threading time, severely reducing the machine's production efficiency. The yield rate also decreases significantly, leading to a substantial increase in costs.

[0006] Copper wire blanks produced by existing traditional methods often contain numerous inclusions, cracks, and porosity defects. During the drawing process using a multi-head wire drawing machine, the defective areas of the copper wire blank are prone to wire breakage, especially when drawing wires with a diameter of φ0.1mm or less.

[0007] Therefore, multi-head wire drawing machines place high demands on the copper wire blanks used, often requiring copper wire blanks with stable performance indicators, good elongation performance, low breakage rate, bright surface, low resistivity, and "zero defects".

[0008] The information disclosed in the background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] This application addresses the aforementioned technical problems by providing a method for producing copper wire blanks for multi-head wire drawing machines. This method can produce copper wire blanks that meet the production requirements of multi-head wire drawing machines. The resulting copper wire blanks exhibit stable performance indicators, good elongation, low breakage rate, bright surface, low resistivity, and low defect rate. When used in multi-head wire drawing machines, the number of wire breaks is only 2 per 12t of wire drawn, significantly reducing the number of wire breaks.

[0010] This application provides a method for producing copper wire blanks for a multi-head wire drawing machine, comprising the following steps:

[0011] Step S1: Using cathode copper material with a purity of 99.99% as raw material, the chemical element content of impurities in the raw material is as follows: Sb < 0.0004%, As < 0.0005%, Pb < 0.0005%, S < 0.0015%, Fe < 0.0010%, total impurities < 0.0065%, and oxygen content < 0.040%.

[0012] Step S2: The raw materials are stacked from the bottom of the vertical furnace to the charging port inside the vertical furnace;

[0013] Step S3: Preheat the temperature of the copper liquid flow section in the vertical furnace system to 1110℃ before production;

[0014] Step S4: Ignite the burners on each layer of the vertical shaft furnace. When the raw material temperature inside the furnace reaches above 1083℃, the solid copper material melts into liquid copper material. Adjust the heat of each layer of the vertical shaft furnace. After the copper material at the bottom of the furnace melts and flows out, the upper layer of copper material loses its support due to the melting of the lower layer and moves downward under its own gravity. After the material level at the charging port of the vertical shaft furnace drops, copper material is added back into the furnace through the charging mechanism. The copper material inside the furnace is then heated by the burners on each layer, so that it is preheated, heated, and melted sequentially from top to bottom before flowing out, maintaining a relatively constant flow of liquid copper at the outlet of the vertical shaft furnace, resulting in liquid copper containing slag.

[0015] Step S5: After the copper liquid containing slag enters the slag tank, the slag it contains floats on the copper liquid. The slag is removed by using a slag removal tool to obtain the slag-removed copper liquid.

[0016] Step S6: Set the CO ratio in the vertical shaft furnace to 0.4%–0.7%, the CO ratio in the lower chute to 0.2%–0.5%, the CO ratio in the slag bin to 0.2%–0.5%, the CO ratio in the holding furnace to 0.4%–0.5%, the CO ratio in the lower chute to 0.5%–1.5%, and the CO ratio in the tundish to 0.4%–0.7%. This allows carbon monoxide to react with copper oxide and cuprous oxide, controlling the oxygen content of the slag-removed copper liquid to 120–400 ppm. This yields copper liquid for continuous casting.

[0017] Step S7: Before continuous casting, maintain the temperature of the casting mold between 95 and 105°C to ensure that the surface of the casting wheel and steel strip of the casting mold is uniformly coated with carbon. Each cooling nozzle is set in the center of the casting wheel and steel strip of the casting mold and flows continuously and smoothly. The flow rate of the cooling nozzles in Zone 1 is arranged from one side to the other in the order of small to large. The temperature of the copper liquid used for continuous casting is maintained between 1110 and 1115°C. The copper liquid flow rate in continuous casting is: 380-460 LPM in Zone 1, 480-580 LPM in Zones 2 and 3, and the copper liquid flow rate in Zone 3 is adjusted according to the temperature of the casting exiting the casting machine. The temperature of the casting is controlled between 890 and 910°C, and the temperature of the cooling water is controlled between 36 and 42°C to obtain the pre-rolled part.

[0018] Step S8: Remove burrs and defects from the edges and corners of the pre-rolled part to obtain a cleaned pre-rolled part;

[0019] Step S9: The pre-rolled part is continuously rolled, with the infeed temperature controlled in the range of 820 to 840°C, and the temperature of the copper wire billet obtained after rolling is in the range of 590 to 610°C.

[0020] Step S10: Spray the obtained copper wire blank with a cooling mixture. The cooling mixture is prepared by mixing isopropanol or ethanol with deionized water. The concentration of isopropanol or ethanol in the cooling mixture is controlled within the range of 0.8% to 1.2%. The temperature of the copper wire blank after reduction and cooling is controlled between 50 and 65°C.

[0021] Step S11: Dry the obtained copper wire blank until its surface moisture content is below 5%, thus obtaining a dried copper wire blank;

[0022] Step S12: Spray atomized wax liquid onto the dry copper wire blank, with the wax liquid concentration controlled between 5% and 8%, to form a wax liquid film on the surface of the dry copper wire blank and obtain the product copper wire blank.

[0023] The copper wire blanks prepared by the above method can fully meet the copper wire drawing requirements of various specifications of multi-head wire drawing machines. During the drawing process, the copper wire blanks have good toughness, good elongation performance, stable drawing performance, are not easy to break, and have a smooth surface with a resistivity better than the national standard. This can save copper material consumption for downstream customers, fully utilize the production capacity efficiency of multi-head wire drawing machines, and reduce the fixed asset investment and labor costs of wire drawing enterprises.

[0024] Preferably, the raw materials include: waste materials, scrap, and milled copper with a copper content of 99.99%.

[0025] Preferably, the oxygen content in the copper solution used for slag removal in step S6 is 250–350 ppm.

[0026] Preferably, the oxygen content in the copper solution used for slag removal in step S6 is 180–380 ppm.

[0027] Preferably, the temperature of the cooling water used in step S7 is controlled between 36 and 42°C.

[0028] Preferably, in step S9, 11 continuous rolling mills are used to roll out... In the copper wire rod, the continuous rolling mills are arranged in sequence, and the deformation parameters of each continuous rolling mill are as follows: After processing by the first rolling mill, the width of the copper wire rod is 68.02 mm, the height is 72.5 mm, and the cross-sectional area is 3801 mm². 2 The deformation is 30.0%;

[0029] The copper wire blank processed by the second rolling mill has a width of 84.00 mm, a height of 35.0 mm, and a cross-sectional area of ​​2239 mm². 2 The deformation percentage was 41.1%.

[0030] The copper wire blank processed by the third rolling mill has a width of 45.90 mm, a height of 41.3 mm, and a cross-sectional area of ​​1322 mm². 2 The deformation was 40.9%;

[0031] After processing by the fourth rolling mill, the copper wire billet has a width of 57.30 mm, a height of 21.6 mm, and a cross-sectional area of ​​805 mm². 2 The deformation was 39.1%;

[0032] After processing by the fifth rolling mill, the copper wire billet has a width of 27.23 mm, a height of 25.8 mm, and a cross-sectional area of ​​506 mm². 2 The deformation was 37.2%;

[0033] The copper wire rod processed by the sixth rolling mill has a width of 35.57 mm, a height of 13.0 mm, and a cross-sectional area of ​​309 mm². 2 The deformation was 38.8%;

[0034] After processing by the seventh rolling mill, the copper wire billet has a width of 16.95 mm, a height of 16.3 mm, and a cross-sectional area of ​​199 mm². 2 The deformation was 35.7%;

[0035] The copper wire rod processed by the eighth rolling mill has a width of 24.25 mm, a height of 8.2 mm, and a cross-sectional area of ​​131 mm². 2 The deformation was 34.4%;

[0036] After processing by the ninth rolling mill, the copper wire billet has a width of 11.78 mm, a height of 11.7 mm, and a cross-sectional area of ​​93.5 mm². 2 The deformation was 28.3%;

[0037] After processing by the tenth rolling mill, the copper wire billet has a width of 15.04 mm, a height of 6.6 mm, and a cross-sectional area of ​​69.7 mm². 2 The deformation is 25.5%;

[0038] After processing by the eleventh rolling mill, the copper wire billet has a width of 8.28 mm, a height of 8.0 mm, and a cross-sectional area of ​​50.27 mm². 2 The deformation was 27.9%.

[0039] Using the above parameters for continuous rolling can achieve the best rolling effect, effectively improve the performance parameters of the obtained copper wire rod, and minimize the number of fractures.

[0040] Preferably, in step S12, the wax nozzles are symmetrically arranged in pairs on both sides of the dried copper wire blank to ensure that all surfaces of the copper wire blank are completely covered with wax.

[0041] Preferably, in step S9, an emulsion with a concentration controlled at 0.6% to 1.8% is continuously sprayed onto the surface of the roll during the rolling process.

[0042] Preferably, the emulsion concentration is 0.9% to 1.5%.

[0043] Preferably, the method further includes: step S13: the size of the obtained copper wire blank is φ0.3mm, φ1.75mm or φ1.6mm, and the copper wire blank is drawn into multi-head wire with a diameter of less than or equal to 0.1mm by a multi-head wire drawing machine.

[0044] The specific method includes the following steps:

[0045] S1, Raw Material Selection

[0046] The raw material for producing copper wire blanks for multi-head wire drawing machines is primarily high-purity cathode copper, supplemented with process waste, scrap, and milled copper, among other high-purity copper materials generated during production. A small amount of standard copper can also be added according to customer resistivity requirements. Common impurities in copper materials are controlled within the range shown in the table below:

[0047] element Sb As Pb S Fe Total impurities Oxygen content mass fraction / %, not greater than 0.0004 0.0005 0.0005 0.0015 0.0010 0.0065 0.040

[0048] S2, Equipment Inspection and Initial Loading

[0049] Before starting production, it is necessary to conduct inspections of all equipment individually and in a coordinated manner to ensure that each piece of equipment can fully meet the requirements for production operation.

[0050] When initially loading copper materials, high-purity cathode copper plates need to be manually placed into the vertical shaft furnace, gradually stacked from the bottom to the charging port. Because the entire furnace chamber is empty before the initial loading, and there is a 10-meter drop from the charging port to the bottom of the furnace, using a charging trolley for mechanical loading during the initial loading poses a risk of damaging the refractory materials inside the furnace. It also easily leads to problems such as poor furnace start-up, blocked copper tapping ports, and burner blockages, thus affecting normal production.

[0051] S3, Furnace system preheating

[0052] Before starting production, the temperature of the copper liquid flow parts of the furnace system must be preheated to above 1100℃ to provide a basic guarantee for the normal flow of copper liquid and to prevent the copper liquid after the vertical furnace melts from solidifying before casting, thus making it impossible to carry out subsequent production work.

[0053] S4, Heating and melting copper materials and feeding

[0054] The burners on each layer of the vertical shaft furnace are ignited to heat the raw materials. When the temperature of the copper material reaches above 1083℃, the solid copper material will melt into liquid copper material. Based on the casting rate and copper material melting rate of the S7 continuous casting process, the firepower of each layer of the vertical shaft furnace is adjusted to maintain a relatively constant flow of liquid copper at the furnace outlet, providing a basic guarantee for the normal casting of the S7 continuous casting process.

[0055] After the copper material at the bottom of the vertical shaft furnace melts and flows out, the copper material at the top, lacking support due to the melting of the lower layer, moves downwards under its own gravity. As the material level at the furnace's charging port decreases, operators add copper material into the furnace via the charging mechanism. The copper material inside is then heated by burners at each level, achieving preheating, heating, and melting sequentially from top to bottom. This cycle is repeated continuously.

[0056] S5, Copper Liquid Slag Removal

[0057] During the melting process of copper, inclusions easily occur in the molten copper due to the presence of other chemical elements within the copper material itself, as well as the shedding of refractory materials from the furnace system and the falling of foreign objects into the furnace. However, most impurities, such as Si, As, S, and their oxides, have a lower density than copper and float on top of the molten copper. The slag floating on the upper layer can be removed using a slag skimmer, thereby purifying and improving the purity of the molten copper.

[0058] S6, Copper Liquid Oxygen Content Control

[0059] The drawing performance requirements for copper wire blanks used in multi-head wire drawing machines are good elongation and low breakage rate. A key measure for controlling these parameters is controlling the oxygen content of the copper wire blank, which primarily involves controlling the liquid oxygen content. This is because oxygen is almost non-fusible in solid copper, but in liquid copper, oxygen dissolves in the copper liquid in an atomic state and combines with some elements to form compounds. Therefore, the oxygen content must be controlled when the copper is in a liquid state. The furnace system uses a mixture of fuel gas and air to heat and melt the copper material. The method for controlling the oxygen content is to control the ratio of fuel gas to air to ensure incomplete combustion, producing CO. CO combines with O in the liquid copper to generate CO2, which is then removed from the liquid copper, thus adjusting the oxygen content in the product. The chemical formula for this entire process is...

[0060] CO + O → CO2

[0061] Generally, the oxygen content requirement for T1 grade copper wire blanks is ≤400ppm, but practice has shown that the drawing performance of copper wire blanks is optimal when the oxygen content is controlled between 180 and 380ppm. When ω[O] < 180ppm, the conductivity, fatigue resistance, and "drawability" of the copper wire blank deteriorate significantly; when ω[O] > 380ppm, the conductivity decreases slowly; when ω[O] > 1000ppm, its conductivity, plasticity, and strength all decrease significantly.

[0062] S7, Continuous Casting

[0063] Continuous casting is the process of continuously casting liquid copper into a fixed-state solid copper. The casting process is one of the key aspects of quality control for copper wire rod products, as casting defects are easily generated during this process. If impurities are introduced into the casting pool during casting, inclusion defects will form. If air bubbles or air fail to completely escape during casting, porosity defects will form. Uneven cooling due to various reasons during casting will result in crack defects. Regardless of the type of defect, all will affect the drawing performance stability of multi-head wire drawing machines and will cause wire breakage during the drawing process.

[0064] During production, the mold cavity temperature for casting is maintained between 95 and 110°C, and the copper molten metal casting temperature is maintained between 1110 and 1120°C. Simultaneously, it is ensured that the casting mold's casting wheel and steel strip are uniformly coated with carbon, avoiding excessive or insufficient coating to prevent casting defects. All cooling nozzles are positioned in the center of the casting mold's casting wheel and steel strip. The cooling nozzles are free of impurities and the cooling water flows smoothly. The nozzle orifice design requires that the flow rate of the nozzles in Zone 1 be arranged in a sequence from low to high to prevent air bubbles from escaping properly due to excessively rapid cooling during casting, thus avoiding "porosity" defects. The water flow rate in Zone 1 is adjusted to 380–460 LPM, the flow rates in Zones 2 and 3 are designed to be 480–580 LPM, and the flow rate in Zone 3 can be adjusted according to the temperature of the casting exiting the casting machine, controlling the casting temperature between 890 and 910°C. The cooling water temperature is controlled between 36 and 42°C.

[0065] S8, Pre-rolled part trimming

[0066] Because the casting molds and casting wheels of the billets cast by the continuous casting machine are circular, and the billets need to pass through an arc-shaped guide device to enter the S9 continuous rolling mill horizontally, the pre-rolled parts need to be straightened by the pre-rolled parts dressing device before entering the rolling mill. The burrs and defects generated at the edges and corners of the pre-rolled parts are removed by the engraving and milling blades installed in the pre-rolled parts dressing device, so as to provide high-quality rolled parts material for the S9 continuous rolling mill.

[0067] S9, continuous rolling

[0068] Depending on the dimensions of the pre-rolled parts and the final copper wire billet, continuous rolling mills can be configured with 9, 11, or 13 stands. Because the S7 continuous casting equipment produces continuous billets, the rolling process is also continuous. Continuous rolling not only reduces the output of head and tail scrap but also facilitates continuous drawing in multi-head wire drawing mills, effectively reducing the risk of wire breakage at the joints.

[0069] The rolling temperature is controlled within the range of 820–840℃, with a billet cross-sectional area of ​​5430 mm². 2 Taking the trapezoidal pre-rolled part as an example, to roll out a copper wire rod with a diameter of φ8mm, a total of 11 rolling mills are required. The deformation parameters of each rolling pass are as follows:

[0070] The copper wire blank processed by the first rolling mill has a width of 68.02 mm, a height of 72.5 mm, and a cross-sectional area of ​​3801 mm². 2 The deformation was 30.0%. After processing by the second rolling mill, the copper wire billet had a width of 84.00 mm, a height of 35.0 mm, and a cross-sectional area of ​​2239 mm². 2The deformation was 41.1%. After processing by the third rolling mill, the copper wire billet had a width of 45.90 mm, a height of 41.3 mm, and a cross-sectional area of ​​1322 mm². 2 The deformation was 40.9%. After processing by the fourth rolling mill, the copper wire billet had a width of 57.30 mm, a height of 21.6 mm, and a cross-sectional area of ​​805 mm². 2 The deformation was 39.1%. After processing by the fifth rolling mill, the copper wire billet had a width of 27.23 mm, a height of 25.8 mm, and a cross-sectional area of ​​506 mm². 2 The deformation was 37.2%. After processing by the sixth rolling mill, the copper wire billet had a width of 35.57 mm, a height of 13.0 mm, and a cross-sectional area of ​​309 mm². 2 The deformation was 38.8%. After processing by the seventh rolling mill, the copper wire billet had a width of 16.95 mm, a height of 16.3 mm, and a cross-sectional area of ​​199 mm². 2 The deformation was 35.7%. After processing by the eighth rolling mill, the copper wire billet had a width of 24.25 mm, a height of 8.2 mm, and a cross-sectional area of ​​131 mm². 2 The deformation is 34.4%.

[0071] After processing by the ninth rolling mill, the copper wire billet has a width of 11.78 mm, a height of 11.7 mm, and a cross-sectional area of ​​93.5 mm². 2 The deformation was 28.3%.

[0072] After processing by the tenth rolling mill, the copper wire billet has a width of 15.04 mm, a height of 6.6 mm, and a cross-sectional area of ​​69.7 mm². 2 The deformation is 25.5%.

[0073] After processing by the eleventh rolling mill, the copper wire billet has a width of 8.28 mm, a height of 8.0 mm, and a cross-sectional area of ​​50.27 mm². 2 The deformation was 27.9%.

[0074] During the rolling process, an emulsion of a certain concentration needs to be continuously sprayed onto the surface of the rolls to cool and lubricate the rolls, and to clean, cool, and restore the rolled workpiece. The concentration of the emulsion is adjusted according to the performance of the emulsion, the wear resistance of the roll surface, and the surface quality requirements of the rolled workpiece, and can be controlled between 0.6% and 1.8%.

[0075] S10, Copper Wire Blank Cooling

[0076] Because the temperature of the copper wire billet is still in the range of 590-610℃ after the last rolling mill, the surface of the copper wire billet is oxidized to copper oxide due to the high temperature and turns black, which ultimately affects the appearance of the copper wire billet and the drawing performance in the multi-head wire drawing machine. Therefore, the rolled copper wire billet needs to be cooled quickly.

[0077] The coolant used for cooling is a mixture of isopropanol or ethanol and deionized water, with the concentration of isopropanol or ethanol controlled between 0.8% and 1.2%. The purpose of adding isopropanol or ethanol is to gradually reduce the oxidized CuO or Cu2O to Cu.

[0078] The temperature of the copper wire blank after reduction and cooling is controlled at 50-65℃ so that the residual heat can be used to dry the residual moisture on the surface of the copper wire blank.

[0079] S11, Drying of copper wire rod

[0080] After cooling the copper wire blank with a mixture of isopropanol or ethanol and deionized water, a significant amount of water droplets remain on the surface. If the blank is not dried before protection and packaging, it will oxidize and turn black in a humid environment over a long period, ultimately affecting both its appearance and its drawing performance. Therefore, it is necessary to dry the copper wire blank.

[0081] Because the copper wire blank production speed is higher than 18m / s, the drying process requires a low-cost and effective method. Therefore, a drying device consisting of compressed air, a circular air sweeping device, an air sweeping chamber, a liquid return pipe, and an air outlet was selected. After drying with this device, the surface moisture content of the copper wire blank is less than 5%.

[0082] S12, copper wire rod protection

[0083] Because copper is easily oxidized by contact with moisture in the air when exposed to air for extended periods, a layer of wax needs to be applied to the surface of the copper wire blank to isolate it from the air. The wax concentration is controlled between 5% and 8%. The wax and compressed air are introduced into the nozzle, and the wax is sprayed onto the surface of the copper wire blank in a mist form. Four nozzles are used simultaneously, spraying from four directions on the copper wire blank to ensure that the surface of the copper wire blank is completely covered with wax.

[0084] S13, Analysis of Copper Wire Rod Coiling and Sampling

[0085] The copper wire blanks used in large wire drawing machines for producing multi-head wire drawing blanks are generally cylindrical copper wire blanks with a diameter of φ8mm. These copper wire blanks are produced at a speed higher than 18m / s. To facilitate transportation, storage, and use, the copper wire blanks are collected by winding during production. The weight of each roll can be set according to the specific needs of the customer. The weight of a single roll is generally 4t to 4.5t. If the weight of a single roll is too low, it will be difficult to control packaging and transportation costs. If the weight of a single roll is too high, the height of the single roll of wire blank will be too high, which may lead to the risk of tilting or tipping over during transportation.

[0086] Since it is impossible to analyze all performance indicators of all copper wire rod products online, only surface defects, iron content, and manual appearance can be detected. However, it is impossible to detect physical properties such as torsional cracks, elongation, torsional fracture value, and copper powder content online, nor can it detect chemical properties such as chemical composition and oxygen content online. Therefore, it is necessary to periodically sample and analyze and test the corresponding performance indicators to make the copper wire rod products more in line with customer needs and relevant standards.

[0087] S14, Copper Wire Rod Packaging

[0088] The qualified wire coil products are compacted, bundled, and wrapped with film for protection to prevent damage during transportation and storage.

[0089] S15, copper wire rod drawing

[0090] Currently, the mainstream multi-head wire drawing machines on the market are medium-sized and small-sized drawing machines. These machines cannot directly use φ8mm copper wire blanks; a large-sized drawing machine is required to draw the copper wire blank to φ...

[0091] 1.75mm and φ1.6mm copper wire blanks are used in multi-head wire drawing machines.

[0092] The beneficial effects that this application can produce include:

[0093] 1) The copper wire blank production method for multi-head wire drawing machine provided in this application effectively increases and reduces the proportion of defects such as inclusions, cracks and pores in the copper wire blank, and the wire breakage rate of the copper wire blank in the multi-head wire drawing machine also decreases significantly.

[0094] 2) The copper wire rod production method for a multi-head wire drawing machine provided in this application exhibits the following specific performance changes in the obtained copper wire rod: The number of cracks in the 15×15 torsion test decreased from 30mm in length to no cracks. The number of torsions required for a 200mm long rod sample to break after 25 clockwise rotations increased from 8 rotations to 28 rotations. The oxygen content of the copper wire rod decreased from a fluctuation of 80–1500ppm to 200–380ppm. The elongation increased from 35% to 43%. The copper powder content in the 250mm gauge length rod sample decreased from 10mg to 3.5mg. This method effectively improves various properties of the obtained copper wire rod.

[0095] 3) The copper wire blank production method for a multi-head wire drawing machine provided in this application, when used to produce copper wire blanks for a 24-head, 25-die multi-head wire drawing machine to draw 0.15mm wire, significantly reduces the wire breakage rate from 18 breaks per 12t of wire drawn to 2 breaks per 12t of wire drawn. This greatly improves the production efficiency of the multi-head wire drawing machine and fully leverages its advantages compared to a single-head wire drawing machine. Attached Figure Description

[0096] Figure 1 A schematic diagram of the copper wire blank production method for a multi-head wire drawing machine provided in this application;

[0097] Figure 2 A schematic diagram of the rolling deformation parameters of each pass for rolling a φ8mm copper wire blank is provided in the embodiments of this application. Detailed Implementation

[0098] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but this does not limit the present invention in any way. Any modifications or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0099] Example

[0100] Unless otherwise specified, all materials and instruments used in the following embodiments were obtained through commercial channels; and all detection methods used are existing methods unless otherwise specified.

[0101] Since the method provided in this application is for continuous production, it cannot be guaranteed that all parameters are point values ​​during the continuous production process. The relevant parameters in the following embodiments are provided as range values.

[0102] Example 1

[0103] This application provides a method for producing copper wire blanks for multi-head wire drawing machines, with the specific steps as follows:

[0104] Step S1: Raw material selection

[0105] Raw materials: High-purity cathode copper is the main raw material, combined with copper materials with a purity of 99.99% produced in other processes, such as scrap, defective products, and milled copper. A small amount of standard copper can also be added according to the customer's resistivity requirements. Common impurities in the copper materials are controlled within the ranges shown in the table below:

[0106] element Sb As Pb S Fe Total impurities Oxygen content mass fraction / %, not greater than 0.0004 0.0005 0.0005 0.0015 0.0010 0.0065 0.040

[0107] Step S2: Equipment inspection and initial loading

[0108] Before starting production, the inspection of each piece of equipment is carried out separately for individual units and in conjunction with the joint commissioning.

[0109] When loading copper materials for the first time, high-purity cathode copper plates are manually placed into the vertical furnace and gradually stacked from the bottom of the furnace to the charging port.

[0110] Step S3: Preheating the furnace system

[0111] Before starting production, preheat the temperature of the copper liquid flow parts of the furnace system to 1110℃.

[0112] Step S4: Heating and melting copper material and adding it

[0113] Ignite the burners on each layer of the vertical shaft furnace to heat the raw materials inside. When the temperature of the copper material inside the furnace reaches above 1083℃, the solid copper material will melt into liquid copper material. Adjust the firepower of each layer of the vertical shaft furnace according to the casting rate and copper material melting rate of the S7 continuous casting process to maintain a relatively constant flow of liquid copper at the furnace outlet.

[0114] After the copper material at the bottom of the vertical shaft furnace melts and flows out, the upper layer of copper material loses its support due to the melting of the lower layer and moves downwards under its own gravity. As the material level at the furnace's charging port drops, copper material is added back into the furnace through the charging mechanism. The copper material inside the furnace is then heated by burners in each layer, achieving preheating, heating, and melting sequentially from top to bottom.

[0115] Step S5: Removal of copper scum

[0116] During the melting process of copper, inclusions can easily occur due to the presence of other chemical elements within the copper material itself, as well as the shedding of refractory materials from the furnace system and the falling of foreign objects into the furnace. However, most impurities, such as Si, As, S, and their oxides, have a lower density than copper. After falling into the molten copper, they will float on top of the copper. When molten copper containing slag enters the slag tank, the slag it contains will float on the upper layer of the molten copper. The resulting slag can be removed using a slag skimmer.

[0117] Step S6: Control of oxygen content in liquid copper

[0118] The oxygen content of the molten copper before casting is controlled at 120–400 ppm. This yields molten copper for continuous casting. The specific operation involves adjusting the CO ratio in the vertical shaft furnace to 0.4%–0.7%, the lower chute to 0.2%–0.5%, the slag bin to 0.2%–0.5%, the holding furnace to 0.4%–0.5%, the lower chute to 0.5%–1.5%, and the tundish to 0.4%–0.7%. This allows carbon monoxide (CO) to react with copper oxide (CuO) and cuprous oxide (Cu₂O), thus controlling the oxygen content.

[0119] Step S7: Continuous casting

[0120] The mold cavity temperature for casting is maintained at 100℃, and the copper molten casting temperature is maintained at 1110℃.

[0121] The temperature should be between 1115℃ and 1115℃. At the same time, ensure that the carbon coating on the casting wheel and steel strip of the casting mold is uniform.

[0122] Each cooling nozzle is positioned precisely in the center of the casting mold's casting wheel and steel strip. The cooling nozzles are free of impurities and blockages, ensuring smooth flow of cooling water.

[0123] The cooling nozzle orifice design is such that the flow rate of the nozzles in Zone 1 is arranged from one side to the other in order of decreasing flow rate, in order to avoid the casting bubbles from being unable to escape properly due to excessively rapid cooling during the casting process, thus forming a "porosity" defect.

[0124] The copper flow rate in zone one is set to 380–460 LPM, and the flow rates in zones two and three are set to 480–580 LPM. The flow rate in zone three is adjusted according to the temperature of the casting exiting the casting machine, controlling the casting temperature at 890–910℃. The cooling water temperature is controlled at 38–40℃. This yields the pre-rolled part.

[0125] Step S8: Pre-rolled part trimming

[0126] Before entering the rolling mill, the pre-rolled parts need to be straightened by the pre-rolled parts dressing device, and the burrs and defects at the edges and corners of the pre-rolled parts are removed by the engraving and milling blades installed in the pre-rolled parts dressing device.

[0127] Step S9: Continuous rolling

[0128] Depending on the dimensions of the pre-rolled part and the final copper wire rod size, a continuous rolling mill with 9, 11, or 13 stands can be selected. The cast billet produced by the continuous casting equipment used in step S7 is then subjected to continuous rolling. The feed temperature for continuous rolling is controlled within the range of 820–840℃.

[0129] See Figure 2 When 11 rolling mills are set up, the infeed temperature is controlled within the range of 820-840℃, with a billet cross-sectional area of ​​5430mm².2 Trapezoidal pre-rolled parts, rolled into Taking copper wire rod as an example, a total of 11 rolling mills are required. The deformation parameters of each rolling pass are as follows: After processing by the first rolling mill, the width of the copper wire rod is 68.02 mm, the height is 72.5 mm, and the cross-sectional area is 3801 mm². 2 The deformation was 30.0%. After processing by the second rolling mill, the copper wire billet had a width of 84.00 mm, a height of 35.0 mm, and a cross-sectional area of ​​2239 mm². 2 The deformation was 41.1%. After processing by the third rolling mill, the copper wire billet had a width of 45.90 mm, a height of 41.3 mm, and a cross-sectional area of ​​1322 mm². 2 The deformation was 40.9%. After processing by the fourth rolling mill, the copper wire billet had a width of 57.30 mm, a height of 21.6 mm, and a cross-sectional area of ​​805 mm². 2 The deformation was 39.1%. After processing by the fifth rolling mill, the copper wire billet had a width of 27.23 mm, a height of 25.8 mm, and a cross-sectional area of ​​506 mm². 2 The deformation was 37.2%. After processing by the sixth rolling mill, the copper wire billet had a width of 35.57 mm, a height of 13.0 mm, and a cross-sectional area of ​​309 mm². 2 The deformation was 38.8%. After processing by the seventh rolling mill, the copper wire billet had a width of 16.95 mm, a height of 16.3 mm, and a cross-sectional area of ​​199 mm². 2 The deformation was 35.7%. After processing by the eighth rolling mill, the copper wire billet had a width of 24.25 mm, a height of 8.2 mm, and a cross-sectional area of ​​131 mm². 2 The deformation is 34.4%.

[0130] After processing by the ninth rolling mill, the copper wire billet has a width of 11.78 mm, a height of 11.7 mm, and a cross-sectional area of ​​93.5 mm². 2 The deformation was 28.3%.

[0131] After processing by the tenth rolling mill, the copper wire billet has a width of 15.04 mm, a height of 6.6 mm, and a cross-sectional area of ​​69.7 mm². 2 The deformation is 25.5%.

[0132] After processing by the eleventh rolling mill, the copper wire billet has a width of 8.28 mm, a height of 8.0 mm, and a cross-sectional area of ​​50.27 mm². 2 The deformation was 27.9%.

[0133] During the rolling process, an emulsion with a concentration controlled between 0.9% and 1.5% needs to be continuously sprayed onto the surface of the rolls.

[0134] Step S10: Cooling of copper wire rod

[0135] The rolled copper wire rod needs to be rapidly cooled. The cooling liquid used is a mixture of ethanol and deionized water, with the concentration of ethanol in the mixture controlled within the range of 0.8% to 1.2%.

[0136] The temperature of the copper wire blank after reduction and cooling is controlled between 50℃ and 65℃.

[0137] Step S11: Drying the copper wire blank

[0138] The resulting copper wire blank is dried using a drying device. After drying, the surface moisture content of the copper wire blank is less than 5%.

[0139] Step S12: Protection of copper wire rod

[0140] A layer of wax solution is applied to the surface of the copper wire blank, with the wax concentration controlled between 5% and 8%. The wax solution and compressed air are then introduced into the wax solution nozzle, which sprays the wax solution onto the surface of the copper wire blank in a mist form. Simultaneously, four nozzles are used on both sides of the copper wire blank to spray from four directions.

[0141] Step S13: Copper wire rod winding and sampling analysis

[0142] The produced copper wire blank is a cylindrical copper wire blank with a diameter of φ8mm. The copper wire blank is produced at a speed of more than 18m / s. During production, the copper wire blank is collected by winding. The weight of a single roll is 4t to 4.5t.

[0143] Regularly sample and analyze the corresponding performance indicators to obtain qualified coils.

[0144] Step S14: Packaging of copper wire blanks

[0145] The qualified yarn rolls are subjected to protective treatment by compaction, bundling, and film packaging.

[0146] Step S15: Drawing copper wire blanks

[0147] The copper wire blanks are drawn into φ1.75mm and φ1.6mm copper wire blanks using a large wire drawing machine for use in multi-head wire drawing machines.

[0148] Example 2

[0149] The difference from Example 1 is as follows: In step S6, the oxygen content is controlled to be 180–380 ppm; in step S7, the mold cavity temperature for casting is maintained at 95–105°C; the copper molten casting temperature is maintained between 1110–1115°C; the cooling water temperature is controlled at 36–42°C; and the spray concentration is controlled at 0.6%–1.8% emulsion. In step S10, the coolant is a mixture of isopropanol and deionized water, and the concentration of isopropanol in the mixture is controlled within the range of 0.8%–1.2%.

[0150] Example 3

[0151] The difference from Example 1 is that the oxygen content in step S6 is controlled to be 250-350 ppm.

[0152] Comparative Example 1

[0153] The difference from Example 1 is that: only cathode copper with a purity of 99.99% is used in step S1; in step S2, the copper material is only stacked to the middle layer in the furnace; and steps S3-4 and S6 are not performed. After the material is stacked, it is directly heated to 1200°C until copper liquid flows out; all other parameters not detailed are operated according to the parameters disclosed in GB / T3952-2016 (copper wire rod for electrical use).

[0154] Performance testing:

[0155] The copper wire blanks obtained in Example 1 and Comparative Example 1 were tested using existing methods, which will not be described in detail here. The results are as follows:

[0156] 1. Random sampling was conducted on the single batch of copper wire blanks obtained in Example 1 and Comparative Example 1. A total of 10m copper wire blanks were tested, with each sample having a length of 1m. The proportion of copper wire blanks with inclusions in the sample length obtained in Example 1 was 2%; the proportion of copper wire blanks with inclusions in the sample length obtained in Comparative Example 1 was 5%.

[0157] The proportion of sample lengths with cracks in Example 1 was 1%; the proportion of sample lengths with cracks in Comparative Example 1 was 4%.

[0158] The proportion of copper wire blanks with porosity in Example 1 was 3%; the proportion of copper wire blanks with porosity in Comparative Example 1 was 4%.

[0159] As can be seen from the results above, the proportion of each type of defect has decreased significantly.

[0160] 2. Wire breakage rate during copper wire drawing in a multi-head wire drawing machine

[0161] The copper wire blanks obtained from randomly sampled Examples 1 and Comparative Example 1 were fed into a multi-head wire drawing machine to test the wire breakage rate.

[0162] The breaking rate of the copper wire blank obtained in Example 1 was 10%; the breaking rate of the copper wire blank obtained in Comparative Example 1 was 20%. The method provided in this application can effectively reduce the breaking rate of the obtained copper wire blank.

[0163] 3. The copper wire blank obtained in Example 1 showed no cracks in a 15×15 torsion test. The copper wire blank obtained in Comparative Example 1 developed a 30mm long crack in a 15×15 torsion test. The method provided in this application can significantly reduce the cracks in the obtained copper wire blank and improve its torsion resistance.

[0164] 4. The copper wire blanks obtained in Example 1 and Comparative Example 1 were all made into rods with a length of 200 mm. The rods were subjected to torsional force testing after rotating forward 25 times and then reversed until breakage. The sample obtained in Example 1 had a torsion count of 28 rotations; the sample obtained in Comparative Example 1 had a torsion count of 8 rotations.

[0165] 5. The oxygen content of the copper wire blanks obtained from randomly sampled Examples 1 and 1 was tested. The oxygen content of the copper wire blanks obtained in Example 1 fluctuated between 200 and 380 ppm. The oxygen content of the copper wire blanks obtained in Comparative Example 1 fluctuated between 80 and 1500 ppm. The fluctuation range was significantly reduced.

[0166] 6. The elongation of the copper wire blanks obtained from randomly sampled Examples 1 and 1 was tested. The elongation of the copper wire blanks obtained from Example 1 was 35%, while the elongation of the copper wire blanks obtained from Example 1 was 43%. The elongation of the obtained copper wire blanks was significantly improved.

[0167] 7. Detection of copper powder content in rod samples of copper wire blanks obtained from Examples 1 and 1 (random sampling) at a gauge length of 250 mm. The copper powder content of the copper wire blanks obtained from Comparative Example 1 was 10 mg; the copper powder content of the copper wire blanks obtained from Example 1 was 3.5 mg.

[0168] 8. The copper wire blanks obtained in Example 1 and Comparative Example 1 were drawn into wires using a multi-head wire drawing machine with 24 heads and 25 dies. When each copper wire blank was drawn into a wire with a diameter of 0.15 mm, the copper wire blank obtained in Example 1 broke only 2 times per 12 tons of wire drawn; the copper wire blank obtained in Comparative Example 1 broke 18 times. The method provided in this application can effectively improve the tensile strength of the obtained copper wire blanks, significantly reduce the breakage rate, and the obtained copper wire blanks can better meet the production needs of multi-head wire drawing machines.

[0169] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing copper wire blanks for a multi-head wire drawing machine, characterized in that, Includes the following steps: Step S1: Using cathode copper material with a purity of 99.99% as raw material, the chemical element content of impurities in the raw material is as follows: Sb < 0.0004%, As < 0.0005%, Pb < 0.0005%, S < 0.0015%, Fe < 0.0010%, total impurities < 0.0065%, and oxygen content < 0.040%. Step S2: The raw materials are stacked from the bottom of the vertical furnace to the charging port inside the vertical furnace; Step S3: Preheat the temperature of the copper liquid flow section in the vertical furnace system to 1110℃ before production; Step S4: Ignite the flames of the burners in each layer of the vertical furnace. When the temperature of the raw material in the furnace reaches above 1083℃, the solid copper material melts into liquid copper material. Adjust the firepower of each layer of the vertical furnace. After the copper material at the bottom of the vertical furnace melts and flows out of the furnace, the upper layer of copper material loses its support due to the melting of the lower layer of copper material. The upper layer of copper material moves downward under its own gravity. After the material level at the charging port of the vertical furnace drops, the copper material is added back into the vertical furnace through the charging mechanism. The copper material in the furnace is then heated by the burners in each layer, so that it is preheated, heated, melted and flows out from top to bottom in sequence, so that the copper liquid flow at the outlet of the vertical furnace is kept relatively constant, and copper liquid containing slag is obtained. Step S5: After the copper liquid containing slag enters the slag tank, the slag it contains floats on the copper liquid. The slag is removed by using a slag removal tool to obtain the slag-removed copper liquid. Step S6: Set the CO ratio of the vertical shaft furnace to 0.4%–0.7%, the CO ratio of the lower chute to 0.2%–0.5%, the CO ratio of the slag bin to 0.2%–0.5%, the CO ratio of the holding furnace to 0.4%–0.5%, the CO ratio of the lower chute to 0.5%–1.5%, and the CO ratio of the tundish to 0.4%–0.7%, so that carbon monoxide reacts with copper oxide and cuprous oxide, and the oxygen content of the slag-removed copper liquid is controlled at 120–400 ppm to obtain copper liquid for continuous casting. Step S7: Before continuous casting, maintain the temperature of the casting mold between 95 and 105°C to ensure that the surface of the casting wheel and steel strip of the casting mold is uniformly coated with carbon. Each cooling nozzle is set in the center of the casting wheel and steel strip of the casting mold and flows continuously and smoothly. The flow rate of the cooling nozzles in Zone 1 is arranged from one side to the other in the order of small to large. The temperature of the copper liquid used for continuous casting is maintained between 1110 and 1115°C. The copper liquid flow rate in continuous casting is: 380-460 LPM in Zone 1, 480-580 LPM in Zones 2 and 3, and the copper liquid flow rate in Zone 3 is adjusted according to the temperature of the casting exiting the casting machine. The temperature of the casting is controlled between 890 and 910°C, and the temperature of the cooling water is controlled between 36 and 42°C to obtain the pre-rolled part. Step S8: Remove burrs and defects from the edges and corners of the pre-rolled part to obtain a cleaned pre-rolled part; Step S9: The impurity-removed pre-rolled part is continuously rolled, and the infeed temperature is controlled within the range of 820 to 840℃. The temperature of the copper wire billet obtained after rolling is within the range of 590 to 610℃. Step S10: Spray the obtained copper wire blank with a cooling mixture. The cooling mixture is prepared by mixing isopropanol or ethanol with deionized water. The concentration of isopropanol or ethanol in the cooling mixture is controlled within the range of 0.8% to 1.2%. The temperature of the copper wire blank after reduction and cooling is controlled between 50 and 65°C. Step S11: Dry the obtained copper wire blank until its surface moisture content is below 5%, thus obtaining a dried copper wire blank; Step S12: Spray atomized wax liquid onto the dry copper wire blank, with the wax liquid concentration controlled between 5% and 8%, to form a wax liquid film on the surface of the dry copper wire blank to obtain the product copper wire blank; In step S9, 11 continuous rolling mills are used to roll φ8mm copper wire rods. The continuous rolling mills are arranged in sequence, and the deformation parameters of each continuous rolling mill are as follows: The copper wire blank processed by the first rolling mill has a width of 68.02 mm, a height of 72.5 mm, and a cross-sectional area of ​​3801 mm². 2 ; The copper wire blank processed by the second rolling mill has a width of 84.00 mm, a height of 35.0 mm, and a cross-sectional area of ​​2239 mm². 2 ; The copper wire blank processed by the third rolling mill has a width of 45.90 mm, a height of 41.3 mm, and a cross-sectional area of ​​1322 mm². 2 ; After processing by the fourth rolling mill, the copper wire billet has a width of 57.30 mm, a height of 21.6 mm, and a cross-sectional area of ​​805 mm². 2 ; After processing by the fifth rolling mill, the copper wire billet has a width of 27.23 mm, a height of 25.8 mm, and a cross-sectional area of ​​506 mm². 2 ; The copper wire rod processed by the sixth rolling mill has a width of 35.57 mm, a height of 13.0 mm, and a cross-sectional area of ​​309 mm². 2 ; After processing by the seventh rolling mill, the copper wire billet has a width of 16.95 mm, a height of 16.3 mm, and a cross-sectional area of ​​199 mm². 2 ; The copper wire rod processed by the eighth rolling mill has a width of 24.25 mm, a height of 8.2 mm, and a cross-sectional area of ​​131 mm². 2 ; After processing by the ninth rolling mill, the copper wire billet has a width of 11.78 mm, a height of 11.7 mm, and a cross-sectional area of ​​93.5 mm². 2 ; After processing by the tenth rolling mill, the copper wire billet has a width of 15.04 mm, a height of 6.6 mm, and a cross-sectional area of ​​69.7 mm². 2 ; After processing by the eleventh rolling mill, the copper wire billet has a width of 8.28 mm, a height of 8.0 mm, and a cross-sectional area of ​​50.27 mm². 2 .

2. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, Raw materials include: Waste with a copper content of 99.99%.

3. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, In step S6, the oxygen content in the copper solution used for slag removal is 250–350 ppm.

4. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, In step S6, the oxygen content in the copper solution used for slag removal is 180–380 ppm.

5. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, The temperature of the cooling water used in step S7 is controlled between 36 and 42°C.

6. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, In step S12, wax nozzles are symmetrically arranged in pairs on both sides of the dried copper wire blank.

7. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, In step S9, during the rolling process, an emulsion with a concentration controlled at 0.6% to 1.8% is continuously sprayed onto the surface of the rolls.

8. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, The emulsion concentration is 0.9% to 1.5%.

9. The method for producing copper wire blanks for a multi-head wire drawing machine according to claim 1, characterized in that, It also includes: Step S13: The size of the obtained copper wire blank is φ0.3mm, φ1.75mm or φ1.6mm, and the copper wire blank is drawn into a multi-head wire with a diameter of less than or equal to 0.1mm by a multi-head wire drawing machine.

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