Oxygen-free copper wire coil grain refinement method

Abstract

The invention discloses a grain refinement method for an oxygen-free copper wire coil. The grain refinement method comprises the following steps: (1) heating an oxygen-free copper cast ingot to 680-720 DEG C within 40 minutes, and then feeding the oxygen-free copper cast ingot into a reverse extruder to be extruded into a wire coil; (2) water-cooling the wire coil extruded in the step (1) to be less than 100 DEG C within 5 minutes to obtain a cooled wire coil; and (3) oxide on the surface of the wire coil cooled in the step (2) is cleaned with acid liquor, and an oxygen-free copper wire coil finished product with the diameter being 15 + / -1 mm and the average grain size being smaller than 80 microns is obtained. Firstly, a low-temperature rapid heating method is adopted, growth of oxygen-free copper cast ingot crystal grains is restrained, and then the oxygen-free copper cast ingot is reversely extruded into a wire coil through a reverse extruding machine. In the extrusion process, the grain growth of the wire coil is inhibited by controlling the extrusion temperature and improving the cooling strength and the cooling speed of the wire coil, and the obtained oxygen-free copper wire coil is small in average grain size and meets the requirements of a new energy market.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, and in particular to a method for refining grains of an oxygen-free copper wire coil. Background Art

[0002] Oxygen-free copper is extremely pure (purity ≥ 99.95%) and has excellent electrical and thermal conductivity. It is widely used in electronics, electrical, communications, aerospace and other fields. With the rapid development of the new energy market, the demand for oxygen-free copper wire coils with the grade of TU0 is increasing. When the normal production volume of the wire coils cannot meet the sudden increase in business demand, the instability of the expedited production process will lead to more wire coil quality problems.

[0003] Downstream customers in the new energy market require that the diameter of oxygen-free copper wire coils is 15±1mm, and the average grain size is required to be less than 80um. However, the TU0 wire coils currently produced by conventional processes have a larger average grain size of about 110-130um. The larger grain size causes downstream customers to have "orange peel" problems after stretching the wire coils. The surface quality does not meet the requirements, and the product qualification rate is only 52%, which cannot meet the performance requirements of end customers. Ultimately, a large number of TU0 wire coils are scrapped and recycled, which increases production costs, extends delivery deadlines, and disrupts the production plans of downstream customers. Summary of the invention

[0004] The present invention provides a method for refining grains of an oxygen-free copper wire coil, the purpose of which is to produce an oxygen-free copper wire coil with a smaller average grain size and meeting the requirements of the new energy market by improving the extrusion process.

[0005] To achieve its purpose, the present invention adopts the following technical solution: A method for refining grains of an oxygen-free copper wire coil, wherein the diameter of the oxygen-free copper wire coil is 15±1 mm, and the average grain size is less than 80 um. The method for refining grains comprises the following steps: (1) The oxygen-free copper ingot is heated to 680-720°C within 40 minutes and then fed into a reverse extruder to be extruded into a wire coil; (2) cooling the wire coil extruded in step (1) to less than 100° C. within 5 minutes to obtain a cooled wire coil; (3) Cleaning the oxide on the surface of the wire coil after cooling in step (2) with an acid solution to obtain a finished oxygen-free copper wire coil with a diameter of 15±1 mm and an average grain size of less than 80 um.

[0006] Furthermore, the oxygen-free copper ingot in step (1) is a TU0 oxygen-free copper ingot with a diameter of φ260±1 mm and a length of 1000±5 mm.

[0007] Furthermore, the oxygen-free copper ingot of step (1) is heated by a medium frequency induction furnace.

[0008] Furthermore, a 35MN reverse extruder is used during extrusion in step (1).

[0009] Furthermore, the extrusion die used in step (1) is a double-hole extrusion die composed of H13 and metal ceramic.

[0010] Furthermore, the extrusion die used in step (1) is lubricated with asphalt.

[0011] Furthermore, during the water cooling in step (2), the cooling water inlet temperature is less than 30°C, and the cooling water is dynamically circulated.

[0012] Furthermore, the acid solution used for cleaning in step (3) is 16-18% H2SO4, and the pickling time is 30-60 minutes.

[0013] The beneficial effects of the present invention are as follows: The method for refining the grains of oxygen-free copper wire coils provided by the present invention first adopts a low-temperature rapid heating method to suppress the growth of the grains of the oxygen-free copper ingot, and then uses a reverse extruder to reversely extrude the oxygen-free copper ingot into a wire coil. During the extrusion process, the growth of the wire coil grains is suppressed by controlling the extrusion temperature and improving the cooling strength and cooling speed of the wire coil, thereby solving the problem of the large average grain size of the TU0 oxygen-free copper extruded wire coil, and producing a TU0 oxygen-free copper wire coil with a small average grain size that meets the requirements of the new energy market, with a high yield rate and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a physical picture of the oxygen-free copper wire coil product in Example 1 of the present invention; Figure 2 This is a physical picture of the oxygen-free copper wire coil product in Example 2 of the present invention; Figure 3 This is a physical picture of the oxygen-free copper wire coil product in Example 3 of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with embodiments: In the following embodiments of the present invention, the extruder is a 35MN reverse extruder provided by the purchaser PRESEZZI, the extrusion die used for extrusion is a H13 and metal ceramic combined double-hole extrusion die, and the extrusion die is lubricated with asphalt.

[0016] Example 1 A method for refining grains of an oxygen-free copper wire coil comprises the following steps: (1) Using the low-temperature rapid heating method, a TU0 oxygen-free copper ingot with a diameter of φ259 mm and a length of 998 mm was sent into a medium-frequency induction furnace for heating for 38 minutes. When the temperature of the TU0 oxygen-free copper ingot was measured to be 680°C, it was sent into an extruder for extrusion into a wire coil; (2) feeding the wire coil extruded in step (1) into a dynamic circulating water tank with an inlet temperature of 25° C. for water cooling, and cooling the wire coil to 50° C. within 4 minutes to obtain a cooled wire coil; (3) The oxide on the surface of the coil after cooling in step (2) was pickled with 16% H2SO4. After pickling for 40 minutes, the following was obtained: Figure 1 The wire coil shown is a finished product of TU0 oxygen-free copper wire coil with a wire coil diameter of 15mm and an average grain size of 75um.

[0017] Example 2 A method for refining grains of an oxygen-free copper wire coil comprises the following steps: (1) Using the low-temperature rapid heating method, a TU0 oxygen-free copper ingot with a diameter of φ260 mm and a length of 1001 mm was sent into a medium-frequency induction furnace for heating for 39 minutes. When the temperature of the TU0 oxygen-free copper ingot was measured to be 700°C, it was sent into an extruder and extruded into a wire coil; (2) sending the wire coil extruded in step (1) into a dynamic circulating water tank with an inlet water temperature of 28° C. for water cooling, and cooling the wire coil to 67° C. within 4 minutes to obtain a cooled wire coil; (3) After the oxide on the surface of the coil is cooled in step (2), the surface is pickled with 18% H2SO4 for 30 minutes to obtain the following: Figure 2 The wire coil shown is a finished product of TU0 oxygen-free copper wire coil with a wire coil diameter of 15 mm and an average grain size of 70 um.

[0018] Example 3 A method for refining grains of an oxygen-free copper wire coil comprises the following steps: (1) Using the low-temperature rapid heating method, a TU0 oxygen-free copper ingot with a diameter of φ261 mm and a length of 1005 mm was sent into a medium-frequency induction furnace for heating for 39 minutes. When the temperature of the TU0 oxygen-free copper ingot was measured to be 720°C, it was sent into an extruder and extruded into a wire coil; (2) sending the wire coil extruded in step (1) into a dynamic circulating water tank with an inlet water temperature of 20° C. for water cooling, and cooling the wire coil to 35° C. within 4 minutes to obtain a cooled wire coil; (3) The oxide on the surface of the coil after cooling in step (2) was pickled with 16% H2SO4. After pickling for 58 minutes, the following was obtained: Figure 3 The wire coil shown is a finished product of TU0 oxygen-free copper wire coil with a wire coil diameter of 16 mm and an average grain size of 70 um.

Claims

1. A method for grain refinement of oxygen-free copper wire coil, characterized in that: The grain refining method comprises the following steps: (1) The oxygen-free copper ingot is heated to 680-720°C within 40 minutes and then fed into a reverse extruder to be extruded into a wire coil; (2) cooling the wire coil extruded in step (1) to less than 100° C. within 5 minutes to obtain a cooled wire coil; (3) Cleaning the oxide on the surface of the wire coil after cooling in step (2) with an acid solution to obtain a finished oxygen-free copper wire coil with a diameter of 15±1 mm and an average grain size of less than 80 um.

2. The method for grain refinement of oxygen-free copper wire coil according to claim 1, characterized in that: The oxygen-free copper ingot in step (1) is a TU0 oxygen-free copper ingot with a diameter of φ260±1 mm and a length of 1000±5 mm.

3. A method for grain refinement of oxygen-free copper wire coil according to claim 2, characterized in that: The oxygen-free copper ingot of step (1) is heated by a medium frequency induction furnace.

4. The method for grain refinement of oxygen-free copper wire coil according to claim 3, characterized in that: In step (1), a 35MN reverse extruder is used for extrusion.

5. The method for grain refinement of oxygen-free copper wire coil according to claim 4, characterized in that: The extrusion die used in step (1) is a H13 and metal-ceramic combined double-hole extrusion die.

6. A method for grain refinement of oxygen-free copper wire coil according to claim 5, characterized in that: The extrusion die used in step (1) extrusion is lubricated with asphalt.

7. A method for grain refinement of oxygen-free copper wire coil according to claim 6, characterized in that: During water cooling in step (2), the cooling water inlet temperature is less than 30°C, and the cooling water is dynamically circulated.

8. The method for grain refinement of oxygen-free copper wire coil according to claim 7, characterized in that: The acid solution used for cleaning in step (3) is 16-18% H2SO4, and the pickling time is 30-60 minutes.

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