Ultrafine copper wire and method for producing the same

Abstract

The application discloses a kind of ultra-fine copper wire and its production method, belong to copper wire production technical field;The production method of ultra-fine copper wire provided by the application includes the following steps: (1) continuous casting and rolling copper pole: after electrolytic copper plate is melted, slag is removed and purified, copper liquid is obtained, then the copper liquid is continuously cast, and the casting blank is obtained, then the casting blank is continuously rolled, acid-free cleaning and waxing, and the copper pole is obtained;(2) continuous drawing and on-line annealing: the copper pole is drawn continuously through multiple passes, first large-diameter drawing, then medium-diameter drawing, on-line continuous annealing while medium-diameter drawing, then small-diameter drawing, and small-diameter copper wire is obtained;(3) micro-drawing and annealing: the small-diameter copper wire is micro-drawn to an average diameter of 0.03-0.05 mm and then annealed to obtain ultra-fine copper wire.The ultra-fine copper wire obtained by the production method provided by the application has a large weight when it breaks for the first time and a large elongation.

Description

Technical Field

[0001] This invention belongs to the field of copper wire production technology, and particularly relates to an ultrafine copper wire and its production method. Background Technology

[0002] With the rapid development of the information age, ultra-fine copper wires are widely used in various precision electrical equipment and electronic products, such as micro motors, high-frequency ultra-fine coaxial wires connecting screens and main units in mobile communication equipment, and fine wires for biochemical and medical applications.

[0003] Currently, the production of ultra-fine copper wire is prone to breakage during the drawing process, severely impacting production efficiency. This is mainly due to the inherent defects introduced into the production process. Existing patents have few reports on controlling these defects. For example, patent document CN108624763A discloses a continuous casting and rolling process for low-oxygen copper rods, but it lacks methods for controlling impurities and defects during this process. Patent document CN104624707A discloses an ultra-fine copper wire production process involving upward drawing of oxygen-free copper rods—drawing—annealing—drawing; however, this process results in numerous defects such as porosity and shrinkage cavities within the upward-drawn copper rods, easily causing breakage during subsequent ultra-fine wire drawing. Furthermore, the upward drawing rate of the copper rods is only 2-3 m / min, resulting in low production efficiency. The patent document number CN102886390A discloses a process for producing ultra-fine copper wires that involves drawing an oxygen-free copper rod upwards, extruding, drawing, annealing, and drawing again. Although the added extrusion process reduces internal void defects to some extent, cold deformation may introduce new defects, leading to wire breakage during subsequent ultra-fine wire drawing. Moreover, the added process complicates the entire production process, and the prepared copper wires do not undergo final processing, resulting in a significantly lower elongation rate. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ultra-fine copper wire with high production efficiency, low breakage rate, and high elongation, as well as a method for producing the same.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for producing ultrafine copper wires, the method comprising the following steps:

[0006] (1) Continuous casting and rolling of copper rods: After melting electrolytic copper plates, slag is removed and purified to obtain copper liquid. Then, the copper liquid is continuously cast to obtain a billet. The billet is then continuously rolled, acid-free cleaned and waxed to obtain a copper rod.

[0007] (2) Continuous drawing and online annealing: The copper rod is continuously drawn through multiple passes. During the drawing process, it is first drawn with a large pull, then a medium pull, and simultaneously annealed online. Then it is drawn with a small pull to obtain a small-draw copper wire.

[0008] (3) Micro-drawing and annealing: After micro-drawing the small copper wire to an average diameter of 0.03-0.05mm, it is annealed to obtain ultra-fine copper wire.

[0009] The method for producing ultrafine copper wires provided by this invention produces ultrafine copper wires with low breakage rate and high elongation, and the production process is simple and efficient. Specifically, firstly, this invention cleans and removes slag after melting electrolytic copper plates. This slag removal process effectively removes oxide impurities, detached furnace charge, and mixed copper slag from the molten copper, effectively reducing the impurity content in the molten copper and contributing to improved elongation of the ultrafine copper wires. Secondly, this invention continuously casts and rolls the molten copper, effectively reducing internal defects and lowering the breakage rate. Thirdly, the continuous rolling followed by acid-free cleaning and waxing effectively isolates the copper rod from the air, reducing surface oxidation and thus lowering the breakage rate. Fourthly, this invention selects online continuous annealing during intermediate drawing, which helps restore the plastic deformation properties of copper, reducing copper damage and lowering the breakage rate.

[0010] In a preferred embodiment of the production method of the present invention, in step (1), the oxygen content of the copper rod is 0.017-0.023%.

[0011] The present invention has found that the range of oxygen content in the copper rod affects the elongation and breakage rate of the prepared copper wire. When the oxygen content in the copper rod is further selected to be 0.017-0.023%, the elongation of the obtained ultrafine copper wire is higher and the breakage rate is lower.

[0012] In a preferred embodiment of the production method of the present invention, the casting temperature in step (1) is 1115-1125℃.

[0013] The present invention has found that the temperature during the casting process affects the state of the billet structure. When the casting temperature is further selected to be 1115-1125℃, the resulting billet structure is finer and more uniform, which is beneficial to improving the elongation of ultrafine copper wires, reducing the wire breakage rate during the production process, and improving production efficiency.

[0014] Preferably, in step (1), before continuously rolling the billet, the step of cooling the billet is also included, and the temperature of the cooled billet is 780-850℃.

[0015] In a preferred embodiment of the production method of the present invention, in step (2), the drawing process first draws the material to an average diameter of 2.95-3.05 mm, then draws it to an average diameter of 1.10-1.15 mm, and then draws it to an average diameter of 0.08-0.16 mm.

[0016] Preferably, in step (2), during the drawing process, the average diameter is first drawn to a large size of 3 mm, then drawn to a medium size of 1.13 mm, and then drawn to a small size of 0.08-0.16 mm.

[0017] In a preferred embodiment of the production method of the present invention, in step (2), an emulsion is used for cooling and lubrication during continuous drawing. During large drawing, the emulsion concentration is 10-12%, the temperature is 33-37℃, and the pH value is 7.5-8.5; during medium drawing, the emulsion concentration is 6-8%, the temperature is 33-37℃, and the pH value is 7.5-8.5; and during small drawing, the emulsion concentration is 4-6%, the temperature is 33-37℃, and the pH value is 7.5-8.5.

[0018] Preferably, in step (2), an emulsion is used for cooling and lubrication during continuous drawing. During large drawing, the emulsion concentration is 10-12%, the temperature is 35°C, and the pH value is 8; during medium drawing, the emulsion concentration is 6-8%, the temperature is 35°C, and the pH value is 8; and during small drawing, the emulsion concentration is 4-6%, the temperature is 35°C, and the pH value is 8.

[0019] It should be noted that the present invention does not particularly limit the emulsion, and any emulsion conventionally used in the art can be used. For example, the emulsion may be a mixture of crude oil and water.

[0020] In one embodiment, the linear speed of the large pull is 900-1200 m / min, and the linear speed of the small pull is 1500-2000 m / min. This invention does not impose special requirements on the linear speeds of the large and small pulls; the objectives of this invention can be achieved within the ranges given herein.

[0021] In a preferred embodiment of the production method of the present invention, in step (2), the voltage of the online continuous annealing is 20-25V and the speed is 400-450m / min.

[0022] This invention has found that the voltage and speed of online continuous annealing both affect the quality of copper wire. When the voltage and speed of online continuous annealing are further selected within the range given in this invention, the elongation of the obtained ultrafine copper wire is even lower.

[0023] In a preferred embodiment of the production method of the present invention, in step (3), an emulsion is used for cooling and lubrication during micro-pulling, with an emulsion concentration of 0.5-2%, a temperature of 20-30℃, and a pH value of 7.5-8.5.

[0024] In a preferred embodiment of the production method of the present invention, in step (3), the linear speed during micro-pulling is 1000-1900m / min.

[0025] In a preferred embodiment of the production method of the present invention, in step (3), the annealing temperature is 350-400℃ and the annealing speed is 250-300m / min.

[0026] This invention has found that annealing after micro-drawing can better improve the elongation of ultrafine copper wires. In particular, when the annealing temperature is further selected to be 350-400℃ and the speed is 250-300m / min, the overall effect of the obtained ultrafine copper wires is even better.

[0027] In a preferred embodiment of the production method of the present invention, in step (1), the average diameter of the copper rod is 7.8-8.2 mm.

[0028] Preferably, in step (1), the average diameter of the copper rod is 8 mm.

[0029] In a preferred embodiment of the production method of the present invention, in step (1), the purity of the electrolytic copper plate is ≥99.99%.

[0030] The requirements for selecting electrolytic copper plates in this invention are that the surface is relatively bright and free of obvious rust, the surface of the copper plate is basically free of copper beads, and the purity of the copper plate is ≥99.99%. Selecting electrolytic copper plates that meet the above requirements can more effectively ensure the quality of copper wire and improve the elongation of ultra-fine copper wire.

[0031] Preferably, the acid-free cleaning is performed using an alcohol solution with a pH range of 8-9.

[0032] It should be noted that there are no particular limitations on the wax used in the application; any wax conventionally available in the art can be used. For example, the wax includes paraffin wax.

[0033] Preferably, in step (1), the coiling rate of the copper rod is 850-950 m / min.

[0034] The continuous casting and rolling of low-oxygen copper rods using the present invention results in a higher coiling rate, which is beneficial for improving production efficiency.

[0035] In a second aspect, the present invention provides an ultrafine copper wire, which is prepared by the production method of the present invention.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention, by selecting a specific production process for ultrafine copper wire, can effectively reduce impurities in the copper wire and improve its plastic deformation ability, thereby resulting in ultrafine copper wire with high elongation, low breakage rate during production, and high production efficiency, which is beneficial for practical production applications. Specifically, when using the production method of this invention, the weight at the first breakage is above 5.1 kg, and the elongation of the obtained ultrafine copper wire is above 10%. Detailed Implementation

[0038] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0039] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in the field; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch.

[0040] Example 1

[0041] This invention provides an ultrafine copper wire, the production method of which includes the following steps:

[0042] (1) Continuous casting and rolling of copper rods: Electrolytic copper plates with a purity of 99.99% and no copper lumps or rust on the surface are added to a vertical furnace for melting. The oxygen content in the vertical furnace is controlled. After melting, the copper is filtered through a slag removal box and then flows into a holding furnace and a tundish. The temperature of the copper liquid in the tundish is 1120℃. Then, the casting billet is continuously cast at the crystallizing wheel at a casting rate of 25.6 tons / hour. After the billet is cooled to 800℃, it is rolled in multiple stands. After rolling to 8mm, the surface is cleaned without acid and coated with wax. Then, it is coiled and wound in a coiler to obtain copper rods. The oxygen content of the copper rods is measured to be 0.0205%.

[0043] (2) Continuous drawing and online annealing: The copper rod is continuously drawn in multiple passes. During the drawing process, an emulsion is used for cooling and lubrication. First, it is drawn to an average diameter of 3.0 mm at a maximum drawing speed of 1000 m / min, with an emulsion concentration of 11%, a temperature of 35°C, and a pH of 8. Then, it is drawn to an average diameter of 1.13 mm at a maximum drawing speed of 7%, a temperature of 35°C, and a pH of 8. During the maximum drawing, online annealing is performed at a pressure of 23 V and a speed of 420 m / min. Next, it is drawn to an average diameter of 0.12 mm at a minimum drawing speed of 1800 m / min, with an emulsion concentration of 5%, a temperature of 35°C, and a pH of 8. The resulting small-drawn copper wire is obtained.

[0044] (3) Micro-drawing and annealing: The small copper wire was micro-drawn to an average diameter of 0.04 mm. The concentration of the micro-drawing emulsion was 1%, the temperature was 25℃, the pH value was 8, and the wire speed was 1300 m / min. Then it was annealed at a temperature of 400℃ and a speed of 300 m / min to obtain ultra-fine copper wire.

[0045] Example 2

[0046] This invention provides an ultrafine copper wire, the production method of which includes the following steps:

[0047] (1) Continuous casting and rolling of copper rods: Electrolytic copper plates with a purity of 99.99% and no copper lumps or rust on the surface are added to a vertical furnace for melting. The oxygen content in the vertical furnace is controlled. After melting, the copper is filtered through a slag removal box and then flows into a holding furnace and a tundish. The temperature of the copper liquid in the tundish is 1115℃. Then, the casting billet is continuously cast at the crystallizing wheel at a casting rate of 25.6 tons / hour. After the billet is cooled to 750℃, it is rolled in multiple stands. After rolling to 8mm, the surface is cleaned without acid and coated with wax. Then, it is coiled and wound up in a coiler to obtain copper rods. The oxygen content of the copper rods is 0.0201%.

[0048] (2) Continuous drawing and online annealing: The copper rod is continuously drawn in multiple passes. During the drawing process, an emulsion is used for cooling and lubrication. First, it is drawn to an average diameter of 3.0 mm at a maximum drawing speed of 1000 m / min, with an emulsion concentration of 12%, a temperature of 35°C, and a pH of 8. Then, it is drawn to an average diameter of 1.13 mm at a medium drawing speed of 8%, with an emulsion concentration of 8%, a temperature of 35°C, and a pH of 8. During the medium drawing, online annealing is performed at a pressure of 23V and a speed of 420 m / min. Next, it is drawn to an average diameter of 0.08 mm at a minimum drawing speed of 1800 m / min, with an emulsion concentration of 4%, a temperature of 35°C, and a pH of 8. The resulting small-drawn copper wire is obtained.

[0049] (3) Micro-drawing and annealing: The small copper wire is micro-drawn to an average diameter of 0.03 mm. The concentration of the micro-drawing emulsion is 1%, the temperature is 30℃, the pH value is 8, and the wire speed is 1050 m / min. Then it is annealed at a temperature of 350℃ and a speed of 250 m / min to obtain ultra-fine copper wire.

[0050] Example 3

[0051] This invention provides an ultrafine copper wire, the production method of which includes the following steps:

[0052] (1) Continuous casting and rolling of copper rods: Electrolytic copper plates with a purity of 99.99% and no copper lumps or rust on the surface are added to a vertical furnace for melting. The oxygen content in the vertical furnace is controlled. After melting, the copper is filtered through a slag removal box and then flows into a holding furnace and a tundish. The temperature of the copper liquid in the tundish is 1125℃. Then, the casting billet is continuously cast at the crystallizing wheel at a casting rate of 25.6 tons / hour. After the billet is cooled to 850℃, it is rolled in multiple stands. After rolling to 8mm, the surface is cleaned without acid and coated with wax. Then, it is coiled and wound in a coiler to obtain copper rods. The oxygen content of the copper rods is 0.0211%.

[0053] (2) Continuous drawing and online annealing: The copper rod is continuously drawn in multiple passes. During the drawing process, an emulsion is used for cooling and lubrication. First, it is drawn to an average diameter of 3.0 mm at a maximum drawing speed of 1000 m / min, with an emulsion concentration of 10%, a temperature of 33℃, and a pH of 8. Then, it is drawn to an average diameter of 1.13 mm at a minimum drawing speed of 6%, a temperature of 37℃, and a pH of 8. During the minimum drawing, online annealing is performed at a pressure of 22V and a speed of 400 m / min. Then, it is drawn to an average diameter of 0.16 mm at a minimum drawing speed of 1800 m / min, with an emulsion concentration of 6%, a temperature of 35℃, and a pH of 8. The resulting small-drawn copper wire is obtained.

[0054] (3) Micro-drawing and annealing: The small copper wire was micro-drawn to an average diameter of 0.05 mm. The concentration of the micro-drawing emulsion was 0.5%, the temperature was 20℃, the pH value was 8, and the wire speed was 1850 m / min. Then it was annealed at a temperature of 350℃ and a speed of 250 m / min to obtain ultra-fine copper wire.

[0055] Example 4

[0056] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that the casting temperature in step (1) is 1095°C.

[0057] Example 5

[0058] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (1), the casting temperature is 1130°C.

[0059] Example 6

[0060] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (2), the voltage of the online continuous annealing is 18V.

[0061] Example 7

[0062] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (2), the voltage of the online continuous annealing is 28V.

[0063] Example 8

[0064] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (2), the online continuous annealing speed is 380 m / min.

[0065] Example 9

[0066] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (2), the online continuous annealing speed is 480 m / min.

[0067] Example 10

[0068] This invention provides an ultra-fine copper wire. The only difference between the production method of the ultra-fine copper wire and that of Example 1 is that in step (3), the wire speed of micro-drawing is 2000m / min.

[0069] Example 11

[0070] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that the annealing temperature in step (3) is 300°C.

[0071] Example 12

[0072] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that the annealing temperature in step (3) is 450°C.

[0073] Example 13

[0074] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (3), the annealing speed is 200 m / min.

[0075] Example 14

[0076] This invention provides an ultrafine copper wire. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (3), the annealing speed is 350 m / min.

[0077] Comparative Example 1

[0078] The present invention provides an ultrafine copper wire in a comparative example. The only difference between the production method of the ultrafine copper wire and that of Example 1 is that in step (2), the wire is drawn and continuously annealed online at the same time.

[0079] Comparative Example 2

[0080] The present invention provides an ultra-fine copper wire in a comparative example. The only difference between the production method of the ultra-fine copper wire and that of Example 1 is that in step (1), the molten copper is not cleaned by slag removal and flows into the holding furnace and intermediate ladle.

[0081] Example of effect

[0082] The effectiveness examples of this invention verify the performance of the ultrafine copper wires prepared in Examples 1-14 and Comparative Examples 1-2, including the following parts:

[0083] 1. Weight at the time of the first wire breakage: The weight at the time of the first wire breakage automatically recorded by the micro-drawing machine;

[0084] 2. Elongation: Measured using a small mechanical testing machine, it is the percentage of the displacement of the copper wire before tensile fracture to the initial gauge length.

[0085] The results are shown in Table 1.

[0086] Table 1

[0087] weight / kg Elongation / % weight / kg Elongation / % Example 1 14.1 17 Example 10 8.5 17 Example 2 7.5 15 Example 11 13.5 12 Example 3 17.8 20 Example 12 13.7 10 Example 4 5.1 10 Example 13 13.2 12 Example 5 5.6 11 Example 14 13.6 11 Example 6 5.7 12 Comparative Example 1 3.8 8 Example 7 6.1 11 Comparative Example 2 2.1 7 Example 8 5.7 12 Example 9 6.3 11

[0088] As can be seen from Table 1, the ultrafine copper wire prepared by the technical solution provided by the present invention has excellent elongation and low breakage rate. The weight of the first breakage is large during the preparation process; the weight of the first breakage is more than 5.1 kg, and the elongation is more than 10%.

[0089] As can be seen from Examples 1 and 4-14, the parameters in the production method provided by the present invention affect the performance of the ultrafine copper wire. When the parameters are further selected within the preferred range of the present invention, the overall performance of the obtained product is better. Specifically, the weight of the first wire break is more than 7.5 kg and the elongation is more than 15%.

[0090] As can be seen from Example 1 and Comparative Example 1, when online continuous annealing is performed during the large drawing phase instead of the intermediate drawing phase, the resulting ultrafine copper wire cannot achieve the effect of the present invention. As can be seen from Example 1 and Comparative Example 2, when slag removal is not performed after melting, the resulting ultrafine copper wire also cannot achieve the purpose of the present invention.

[0091] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for producing ultrafine copper wire, characterized in that, The production method includes the following steps: (1) Continuous casting and rolling of copper rods: After melting electrolytic copper plates, slag is removed and purified to obtain copper liquid. The copper liquid is then continuously cast to obtain a billet. The billet is then continuously rolled, acid-free cleaned and waxed to obtain a copper rod. (2) Continuous drawing and online annealing: The copper rod is continuously drawn through multiple passes. During the drawing process, it is first drawn with a large pull, then with a medium pull, and simultaneously with the medium pull, it is continuously annealed online, followed by a small pull; thus, a small-draw copper wire is obtained. (3) Micro-drawing and annealing: After micro-drawing the small copper wire to an average diameter of 0.03-0.05 mm, annealing is performed to obtain ultra-fine copper wire; In step (1), the casting temperature is 1115-1125℃; In step (1), the oxygen content of the copper rod is 0.017-0.023%; In step (2), the voltage for online continuous annealing is 20-25 V, and the speed is 400-450 m / min; In step (3), the annealing temperature is 350-400℃ and the annealing speed is 250-300m / min; In step (2), during the drawing process, the material is first drawn to an average diameter of 2.95-3.05 mm, then drawn to an average diameter of 1.10-1.15 mm, and then drawn to an average diameter of 0.08-0.16 mm.

2. The production method according to claim 1, characterized in that, In step (2), an emulsion is used for cooling and lubrication during continuous drawing. During large drawing, the emulsion concentration is 10-12%, the temperature is 33-37℃, and the pH value is 7.5-8.

5. During medium drawing, the emulsion concentration is 6-8%, the temperature is 33-37℃, and the pH value is 7.5-8.

5. During small drawing, the emulsion concentration is 4-6%, the temperature is 33-37℃, and the pH value is 7.5-8.

5.

3. The production method according to claim 1, characterized in that, In step (3), an emulsion is used for cooling and lubrication during micro-pulling. The emulsion concentration is 0.5-2%, the temperature is 20-30℃, and the pH value is 7.5-8.

5. And / or, the linear speed during micro-extraction is 1000-1900 m / min.

4. The production method according to claim 1, characterized in that, In step (1), the average diameter of the copper rod is 7.8-8.2 mm.

5. An ultrafine copper wire, characterized in that, The ultrafine copper wire is prepared by the production method described in any one of claims 1-4.