Short process preparation method of high-purity oxygen-free copper flat wire
By using a method of zoned heating and synergistic deoxidation with a covering agent, combined with hot continuous casting and cold rolling processes, the problems of high oxygen content and poor surface quality of oxygen-free copper flat wire were solved, and the preparation of high-purity oxygen-free copper flat wire was achieved, meeting the high voltage and high energy efficiency requirements of new energy vehicles.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA WEAPON SCI ACADEMY NINGBO BRANCH
- Filing Date
- 2026-02-26
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies for preparing oxygen-free copper flat wires suffer from problems such as high oxygen content, poor surface quality, and numerous internal defects, making it difficult to meet the requirements of high-efficiency drive motors for new energy vehicles.
The method employs zoned heating and synergistic deoxidation with covering agents, combined with hot continuous casting and multi-pass cold rolling processes. The first and second covering agents are used for diffusion deoxidation and heat preservation under non-vacuum conditions. The deoxidation process is accelerated by mixed gas, and casting defects are removed by hot continuous casting. Finally, cold rolling and annealing are performed.
This technology achieves copper flat wires with an oxygen content of less than 5 ppm, a purity of more than 99.99%, high conductivity, and a smooth, defect-free surface. It simplifies the process, improves production efficiency, and meets the high voltage and high energy efficiency requirements of new energy vehicles.
Smart Images
Figure CN122279245A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of copper wire preparation technology, specifically to a short-process preparation method for high-purity oxygen-free copper flat wire. Background Technology
[0002] With the booming development of the new energy vehicle industry, drive motors are constantly being upgraded towards higher voltage, higher energy efficiency, higher reliability, and miniaturization. Compared with round wire motors, flat wire motors have advantages such as higher energy density, better heat dissipation, lower cost, lower noise, and lighter weight, which are more in line with the development trend of high-efficiency drive motors for new energy vehicles. Currently, the main technical routes for preparing oxygen-free copper flat wires are: dip coating forming-wire drawing, semi-continuous casting-hot extrusion-wire drawing, and upward continuous casting-continuous extrusion-wire drawing.
[0003] Copper flat wires prepared by dip coating-drawing have low oxygen content but a high amount of copper powder on the surface, and the process is complex, difficult to control, and costly. Copper flat wires prepared by semi-continuous casting-hot extrusion-drawing have less copper powder on the surface but high oxygen content, and the process is lengthy. Copper flat wires prepared by upward continuous casting-continuous extrusion-drawing have low oxygen content and less copper powder on the surface, but the upward continuous casting copper rod has obvious casting defects such as porosity and looseness, which harm subsequent processing; segregation easily occurs at the pitch lines on the surface of the upward continuous casting copper rod, leading to locally high oxygen content; unavoidable surface defects such as bubbles, peeling, and oxidation exist during continuous extrusion and drawing, which cannot meet the surface quality requirements of future high-efficiency drive motors for copper flat wires.
[0004] Therefore, improvements are needed to the existing copper flat wires. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a short-process preparation method for high-purity oxygen-free copper flat wire with high purity, low oxygen content, good surface quality and few internal defects, in light of the above-mentioned technical status.
[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a short-process preparation method for high-purity oxygen-free copper flat wire, characterized by including the following steps:
[0007] S1. Smelting: The cathode copper raw material is added to the partitioned heating smelting furnace and heated to obtain copper liquid. The copper liquid is covered with a first covering agent. At the same time, mixed gas is introduced into the bottom of the partitioned heating smelting furnace for deoxidation and impurity removal to obtain copper liquid. The first covering agent is calcined charcoal.
[0008] S2. Heat preservation: The copper liquid is transferred to a heat preservation furnace for heat preservation and covered with a second covering agent. At the same time, a mixed gas is introduced into the bottom of the heat preservation furnace for deoxidation and impurity removal. The second covering agent includes 45-55% calcined charcoal and 45-55% high-purity graphite particles by mass.
[0009] S3. Casting: The hot continuous casting method is used to continuously cast and pull the copper liquid after heat preservation to obtain the billet;
[0010] S4. Cold rolling: The billet is rolled in multiple passes at room temperature to obtain a cold-rolled billet.
[0011] S5. Finish rolling: Cold-rolled billets are finished to obtain copper flat wires;
[0012] S6. Annealing: Stress-relieving annealing is performed on the copper flat wire obtained by precision rolling.
[0013] S7. Cleaning and slitting: After cleaning, the annealed copper flat wire is slitted to obtain the required high-purity oxygen-free copper flat wire.
[0014] Preferably, in step S1, the zonal heating means that the sidewalls and bottom of the smelting furnace can be heated independently; the sidewall heating temperature is 1140~1170℃, and the bottom heating temperature is 1180~1220℃.
[0015] Preferably, in step S1, the thickness of the first covering agent is 160-200 mm, and the calcined charcoal comprises 55-65% by mass of amorphous carbon and 35-45% by mass of layered carbon. Amorphous carbon is highly reactive and easily combines with oxygen in the molten copper to achieve deoxidation, while layered carbon is not easily oxidized and can act as a covering to isolate air. If the covering agent layer is too thin, the deoxidation and heat preservation effects will be insufficient. If the covering agent layer is too thick, it will cause severe carbonization of the molten copper and hinder the escape of bottom-blown gas. Therefore, the thickness of the first covering agent is 160-200 mm.
[0016] Preferably, the mixed gas in steps S1 and S2 consists of 15-20% CO and 80-85% Ar by volume; the pressure of the mixed gas is 0.3-0.6 MPa, and the flow rate is 0.1-10 L / min. This mixed gas effectively reduces Cu2O with CO without causing excessive CO to react with water vapor and produce H2, thus avoiding waste and ensuring safety.
[0017] Preferably, the thickness of the second covering agent in step S2 is 150-200 mm. If the covering agent layer is too thin, the deoxidation and heat preservation effects will be insufficient. If the covering agent layer is too thick, it will cause severe carbonization of the copper liquid and will not be conducive to the escape of bottom-blown gas. Therefore, the thickness of the second covering agent is 150-200 mm.
[0018] Preferably, in step S3, the mold heating temperature is 1100~1110℃, the continuous casting speed is 50~150mm / min, and cooling is carried out during continuous casting and billet pulling, with a cooling water volume of 20~50L / h and a cooling distance of 25~50mm from the mold outlet.
[0019] Preferably, the thickness of the billet obtained in step S3 is 10~80mm and the width of the billet is 10~500mm.
[0020] Preferably, the reduction rate per rolling pass in step S4 is 15% to 70%, and the number of rolling passes is 2 to 10.
[0021] Preferably, the reduction rate per pass of the finishing rolling in step S5 is 2% to 15%, and the number of rolling passes is 2 to 5.
[0022] Preferably, in step S6, the annealing temperature is 150~250℃, the annealing time is 15~30min, and the annealing atmosphere is N2 protection.
[0023] Compared with the prior art, the advantages of the present invention are as follows: under non-vacuum conditions, two different high-efficiency deoxidizing agents, namely a first covering agent and a second covering agent, are used to achieve diffusion deoxidation and covering heat preservation. The mixed gas is fed into the bottom in a coordinated manner, and the density of the melt at the bottom is lower than that at the top through zoned heating, so that it rolls upward to accelerate diffusion deoxidation. In the hot continuous casting process, the directional solidification of the melt is used to further remove impurities, so as to achieve the high-purity oxygen-free copper flat wire with an oxygen content of ≤5ppm, copper purity of ≥99.99%, and conductivity of ≥101%IACS, which meets the requirements of the development trend of high voltage, high energy efficiency and high reliability of drive motors for winding conductors.
[0024] By using hot continuous casting technology to pull copper molten metal into billets, a billet with a bright and smooth surface and no casting defects such as shrinkage cavities and porosity is obtained. Furthermore, the number of grain boundaries inside the billet is greatly reduced, which significantly reduces the deformation resistance during cold working and eliminates the need for intermediate annealing, thereby improving production efficiency.
[0025] The preparation process only involves cold rolling deformation of the billet, which not only simplifies the process flow, but also avoids defects such as bubbles and oxide inclusions on the surface of the copper material during extrusion processing, as well as defects such as copper powder, peeling, and oil stains on the surface caused by high-temperature friction during wire drawing, thus ensuring the surface quality of the copper flat wire. Attached Figure Description
[0026] Figure 1 This is a flowchart illustrating an embodiment;
[0027] Figure 2 The image shows a physical sample of the oxygen-free copper alloy prepared for this example. Detailed Implementation
[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0029] Example 1
[0030] like Figure 1As shown, a short-process method for preparing high-purity oxygen-free copper flat wire includes the following steps:
[0031] Pretreatment: The granules, copper beads, and copper nodules on the cathode copper raw material are removed and cleaned, then placed in a heating furnace and preheated at 170℃ for 3 minutes to dry. Prepare calcined charcoal with a mass fraction of 60% amorphous carbon and 40% layered carbon as the first covering agent, and calcined charcoal with a mass fraction of 50% calcined charcoal and 50% high-purity graphite particles as the second covering agent.
[0032] S1. Melting: The dried cathode copper raw material is added to the melting furnace. The crucible sidewalls and bottom are heated simultaneously to melt the raw material, resulting in molten copper. After the melt temperature reaches 1140℃ and is held for 10 minutes, the bottom is independently heated to raise the local temperature to 1190℃. A first covering agent is used to cover the molten copper, with a covering layer thickness of 180mm. Simultaneously, 15% CO and 85% high-purity Ar (by volume) are blown into the furnace from the bottom at a pressure of 0.4 MPa and a flow rate of 8 L / min. The purity of the high-purity Ar is ≥5N.
[0033] S2. Insulation: The molten copper is transferred to an insulation furnace for insulation at a temperature of 1140℃. A second covering agent is used, with a covering layer thickness of 180mm. Simultaneously, 15% CO and 85% high-purity Ar by volume are blown into the furnace from the bottom at a pressure of 0.4 MPa and a flow rate of 8 L / min.
[0034] S3. Casting: The molten copper in the holding furnace is continuously cast into billets using the hot-mold continuous casting method. Cooling water is circulated during the casting process. The mold heating temperature is 1100℃, the continuous casting speed is 100mm / min, the cooling water flow rate is 40L / h, and the cooling distance is 30mm from the mold outlet. The billet thickness is 20mm and the width is 200mm.
[0035] S4. Cold rolling: The billet is rolled at room temperature using a cold rolling mill. The reduction rate is 50% for the first pass, 50% for the second pass, 40% for the third pass, and 33% for the fourth pass.
[0036] S5. Finishing: The billet is finished using a reversible hydraulic cold rolling mill. The reduction rate is 15% for the first pass, 10% for the second pass, and 2% for the third pass.
[0037] S6. Annealing: Stress-relief annealing is performed on the fine-rolled copper flat wire at a temperature of 180℃ for 25 minutes under N2 protection.
[0038] S7. Cleaning and Slitting: The surface of the copper flat wire is cleaned, and then it is slitted according to the usage requirements using a slitting device. This yields 1.5mm thick wires. Figure 2The oxygen-free copper flat wire shown has a copper purity of 99.998%, an oxygen content of 3ppm, a conductivity of 101.7% IACS, and a smooth and flat surface.
[0039] Example 2
[0040] A short-process method for preparing high-purity oxygen-free copper flat wire includes the following steps:
[0041] Pretreatment: The granules, copper beads, and copper nodules on the cathode copper raw material are removed and cleaned, then placed in a heating furnace and preheated at 170℃ for 3 minutes to dry. A first covering agent is prepared by mixing 60% by mass of amorphous carbon and 40% by mass of calcined charcoal containing layered carbon, and a second covering agent is prepared by mixing 50% by mass of calcined charcoal and 50% by mass of high-purity graphite particles.
[0042] S1. Melting: The dried cathode copper raw material is added to the melting furnace. The crucible sidewalls and bottom are heated simultaneously to melt the raw material, resulting in molten copper. After the melt temperature reaches 1150℃ and is held for 8 minutes, the bottom is independently heated to raise the local temperature to 1190℃. A first covering agent is used to cover the molten copper, with a covering layer thickness of 190mm. At the same time, 15% CO and 85% high-purity Ar (by volume) are blown into the furnace from the bottom at a pressure of 0.3 MPa and a flow rate of 7 L / min. The purity of the high-purity Ar is ≥5N.
[0043] S2. Insulation: The molten copper is transferred to an insulation furnace for insulation at a temperature of 1125℃. A second covering agent is used, with a covering layer thickness of 170mm. Simultaneously, 15% CO and 85% high-purity Ar by volume are blown into the furnace from the bottom at a pressure of 0.3MPa and a flow rate of 7L / min.
[0044] S3. Casting: The molten copper in the holding furnace is continuously cast into billets using the hot-mold continuous casting method. Cooling water is circulated during the casting process. The mold heating temperature is 1105℃, the continuous casting speed is 100mm / min, the cooling water flow rate is 30L / h, and the cooling distance is 30mm from the mold outlet. The billet thickness is 20mm and the width is 200mm.
[0045] S4. Cold rolling: The billet is rolled at room temperature using a cold rolling mill. The reduction rate is 50% for the first pass, 40% for the second pass, 30% for the third pass, 25% for the fourth pass, and 20% for the fifth pass.
[0046] S5. Finishing: The billet is finished using a reversible hydraulic cold rolling mill. The reduction rate is 8% for the first pass, 8% for the second pass, and 6% for the third pass.
[0047] S6. Annealing: Stress-relief annealing is performed on the fine-rolled copper flat wire at a temperature of 170℃ for 28 minutes under N2 protection.
[0048] S7. Cleaning and Slitting: The surface of the copper flat wire is cleaned, and then slitting equipment is used to slit it according to the usage requirements. 2mm thick oxygen-free copper flat wire is obtained, with a copper purity of 99.996%, an oxygen content of 4ppm, a conductivity of 101.6% IACS, and a smooth and flat surface.
[0049] Example 3
[0050] A short-process method for preparing high-purity oxygen-free copper flat wire includes the following steps:
[0051] Pretreatment: The granules, copper beads, and copper nodules on the cathode copper raw material are removed and cleaned, then placed in a heating furnace and preheated at 160℃ for 4 minutes to dry. A first covering agent is prepared by mixing 60% by mass of amorphous carbon and 40% by mass of calcined charcoal containing layered carbon, and a second covering agent is prepared by mixing 50% by mass of calcined charcoal and 50% by mass of high-purity graphite particles.
[0052] S1. Melting: The dried cathode copper raw material is added to the melting furnace. The crucible sidewalls and bottom are heated simultaneously to melt the raw material, resulting in molten copper. After the melt temperature reaches 1160℃ and is held for 8 minutes, the bottom is independently heated to raise the local temperature to 1200℃. A first covering agent is used to cover the molten copper, with a covering layer thickness of 190mm. Simultaneously, 15% CO and 85% high-purity Ar (by volume) are blown into the furnace from the bottom at a pressure of 0.4 MPa and a flow rate of 7 L / min. The purity of the high-purity Ar is ≥5N.
[0053] S2. Insulation: The molten copper is transferred to an insulation furnace for insulation at a temperature of 1130℃. A second covering agent is used, with a covering layer thickness of 190mm. Simultaneously, 15% CO and 85% high-purity Ar by volume are blown into the furnace from the bottom at a pressure of 0.4MPa and a flow rate of 7L / min.
[0054] S3. Casting: The molten copper in the holding furnace is continuously cast into billets using the hot-mold continuous casting method. Cooling water is circulated during the casting process. The mold heating temperature is 1105℃, the continuous casting speed is 80mm / min, the cooling water flow rate is 35L / h, and the cooling distance is 30mm from the mold outlet. The billet thickness is 20mm and the width is 200mm.
[0055] S4. Cold rolling: The billet is rolled at room temperature using a cold rolling mill. The reduction rate is 60% for the first pass, 50% for the second pass, 30% for the third pass, 20% for the fourth pass, and 20% for the fifth pass.
[0056] S5. Finishing Rolling: The billet is finished using a reversible hydraulic cold rolling mill. The reduction rate is 15% for the first pass, 10% for the second pass, 8% for the third pass, and 5% for the fourth pass.
[0057] S6. Annealing: Stress-relief annealing is performed on the fine-rolled copper flat wire at a temperature of 160℃ for 29 minutes under N2 protection.
[0058] S7. Cleaning and Slitting: The surface of the copper flat wire is cleaned, and then slitting equipment is used to slit it according to the usage requirements. A 1.2mm thick oxygen-free copper flat wire is obtained, with a copper purity of 99.997%, an oxygen content of 4ppm, a conductivity of 101.2% IACS, and a smooth and flat surface.
[0059] Example 4
[0060] A short-process method for preparing high-purity oxygen-free copper flat wire includes the following steps:
[0061] Pretreatment: The granules, copper beads, and copper nodules on the cathode copper raw material are removed and cleaned, then placed in a heating furnace and preheated at 160℃ for 4 minutes to dry. A first covering agent is prepared by mixing 60% by mass of amorphous carbon and 40% by mass of calcined charcoal containing layered carbon, and a second covering agent is prepared by mixing 50% by mass of calcined charcoal and 50% by mass of high-purity graphite particles.
[0062] S1. Melting: The dried cathode copper raw material is added to the melting furnace. The crucible sidewalls and bottom are heated simultaneously to melt the raw material, resulting in molten copper. After the melt temperature reaches 1155℃ and is held for 8 minutes, the bottom is independently heated to raise the local temperature to 1195℃. A first covering agent is used to cover the molten copper, with a covering layer thickness of 200mm. Simultaneously, 15% CO and 85% high-purity Ar (by volume) are blown into the furnace from the bottom at a pressure of 0.4 MPa and a flow rate of 8 L / min. The purity of the high-purity Ar is ≥5N.
[0063] S2. Insulation: The molten copper is transferred to an insulation furnace for insulation at a temperature of 1120℃. A second covering agent is used, with a covering layer thickness of 180mm. Simultaneously, 15% CO and 85% high-purity Ar by volume are blown into the furnace from the bottom at a pressure of 0.4 MPa and a flow rate of 8 L / min.
[0064] S3. Casting: The molten copper in the holding furnace is continuously cast into billets using the hot-mold continuous casting method. Cooling water is circulated during the casting process. The mold heating temperature is 1105℃, the continuous casting speed is 110mm / min, the cooling water flow rate is 43L / h, and the cooling distance is 30mm from the mold outlet. The billet thickness is 20mm and the width is 200mm.
[0065] S4. Cold rolling: The billet is rolled at room temperature using a cold rolling mill. The reduction rate is 50% for the first pass, 50% for the second pass, 40% for the third pass, and 30% for the fourth pass.
[0066] S5. Finishing Rolling: The billet is finished using a reversible hydraulic cold rolling mill. The reduction rate is 15% for the first pass, 10% for the second pass, 5% for the third pass, and 2% for the fourth pass.
[0067] S6. Annealing: Stress-relief annealing is performed on the fine-rolled copper flat wire at a temperature of 220℃ for 20 minutes under N2 protection.
[0068] S7. Cleaning and Slitting: The surface of the copper flat wire is cleaned, and then slitting equipment is used to slit it according to the usage requirements; 1.5mm thick oxygen-free copper flat wire is obtained, with a copper purity of 99.996%, an oxygen content of 3ppm, a conductivity of 101.5%IACS, and a smooth and flat surface.
[0069] Comparative Example 1
[0070] The difference between this comparative example and Example 1 is that bottom heating was omitted. The resulting flat copper wire has a purity of 99.985%, an oxygen content of 12 ppm, and a conductivity of 100.2% IACS. The oxygen content in this comparative example is much higher than that in the example, while the purity and conductivity are lower.
[0071] Comparative Example 2
[0072] The difference between this comparative example and Example 2 is that the mold was not heated, cold casting was used, the billet had a large number of casting defects, and cracks appeared during the fourth cold rolling pass.
[0073] Comparative Example 3
[0074] The difference between this comparative example and Example 3 is that after hot continuous casting, cold rolling was not performed, but wire drawing was used, resulting in copper powder on the surface of the copper flat wire and poor surface quality.
Claims
1. A short-process method for preparing high-purity oxygen-free copper flat wire, characterized in that: Includes the following steps: S1. Smelting: The cathode copper raw material is added to the partitioned heating smelting furnace and heated to obtain copper liquid. The copper liquid is covered with a first covering agent. At the same time, mixed gas is introduced into the bottom of the partitioned heating smelting furnace for deoxidation and impurity removal. The first covering agent is calcined charcoal. S2. Heat preservation: The copper liquid is transferred to a heat preservation furnace for heat preservation and covered with a second covering agent. At the same time, a mixed gas is introduced into the bottom of the heat preservation furnace for deoxidation and impurity removal. The second covering agent includes 45-55% calcined charcoal and 45-55% high-purity graphite particles by mass. S3. Casting: The hot continuous casting method is used to continuously cast and pull the copper liquid after heat preservation to obtain the billet; S4. Cold rolling: The billet is rolled in multiple passes at room temperature to obtain a cold-rolled billet. S5. Finish rolling: Cold-rolled billets are finished to obtain copper flat wires; S6. Annealing: Stress-relieving annealing is performed on the copper flat wire obtained by precision rolling. S7. Cleaning and slitting: After cleaning, the annealed copper flat wire is slitted to obtain the required high-purity oxygen-free copper flat wire.
2. The short-process preparation method for high-purity oxygen-free copper flat wire according to claim 1, characterized in that: In step S1, the zonal heating means that the sidewalls and bottom of the smelting furnace can be heated independently; the sidewall heating temperature is 1140~1170℃, and the bottom heating temperature is 1180~1220℃.
3. The short-process preparation method for high-purity oxygen-free copper flat wire according to claim 1, characterized in that: In step S1, the thickness of the first covering agent is 160-200 mm, and the calcined charcoal includes 55-65% amorphous carbon and 35-45% layered carbon.
4. The short-process preparation method for high-purity oxygen-free copper flat wire according to claim 1, characterized in that: In steps S1 and S2, the mixed gas consists of 15-20% CO and 80-85% Ar by volume; the pressure of the mixed gas is 0.3-0.6 MPa, and the flow rate of the mixed gas is 0.1-10 L / min.
5. The short-process preparation method for high-purity oxygen-free copper flat wire according to claim 1, characterized in that: The thickness of the second covering agent in step S2 is 150-200 mm.
6. The short-process preparation method for high-purity oxygen-free copper flat wire according to any one of claims 1-5, characterized in that: In step S3, the mold heating temperature is 1100~1110℃, the continuous casting speed is 50~150mm / min, and cooling is carried out during continuous casting and billet pulling, with a cooling water volume of 20~50L / h and a cooling distance of 25~50mm from the mold outlet.
7. The short-process preparation method for high-purity oxygen-free copper flat wire according to any one of claims 1-5, characterized in that: The thickness of the billet obtained in step S3 is 10~80mm and the width of the billet is 10~500mm.
8. The short-process preparation method for high-purity oxygen-free copper flat wire according to any one of claims 1-5, characterized in that: In step S4, the reduction rate per rolling pass is 15% to 70%, and the number of rolling passes is 2 to 10.
9. The short-process preparation method for high-purity oxygen-free copper flat wire according to any one of claims 1-5, characterized in that: In step S5, the reduction rate per pass of the finishing rolling is 2% to 15%, and the number of rolling passes is 2 to 5.
10. The short-process preparation method for high-purity oxygen-free copper flat wire according to any one of claims 1-5, characterized in that: In step S6, the annealing temperature is 150~250℃, the annealing time is 15~30min, and the annealing atmosphere is N2 protection.