Ultrafine copper wire and production method thereof

Abstract

The invention discloses an ultra-fine copper wire and a production method thereof, and belongs to the technical field of copper wire production. The production method of the ultra-fine copper wire comprises the following steps: (1) continuously casting and rolling a copper rod, namely melting an electrolytic copper plate, deslagging and purifying to obtain a copper solution, continuously casting the copper solution to obtain a casting blank, and continuously rolling, acid-free cleaning and waxing the casting blank to obtain the copper rod; (2) continuous drawing and on-line annealing: the copper rod is subjected to multi-pass continuous drawing, in the drawing process, large drawing is carried out firstly, then medium drawing is carried out, on-line continuous annealing is carried out while medium drawing is carried out, and then small drawing is carried out, so that a small-drawn copper wire is obtained; and (3) micro-drawing and annealing are conducted, specifically, the small-drawn copper wire is subjected to micro-drawing till the average diameter is 0.03-0.05 mm, then annealing is conducted, and the ultra-fine copper wire is obtained. The ultra-fine copper wire obtained by adopting the production method provided by the invention is large in weight and large in elongation rate when being broken for the first time.

Description

Technical Field

[0001] The invention belongs to the technical field of copper wire production, and in particular relates to an ultra-fine copper wire and a production method thereof. Background Art

[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 the screen and the host in mobile communication equipment, and fine biochemical and medical wires.

[0003] At present, the problem of wire breaking is easy to occur during the drawing of ultra-fine copper wires in production, which seriously affects the production efficiency. This is mainly related to the defects that are easily introduced in its production process. There are few reports on the control research on reducing the defects introduced in the production process in the existing patents. For example, patent document number CN108624763A discloses a continuous casting and rolling process for low-oxygen copper rods, but there is no control method for impurity defects in the continuous casting and rolling process. Patent document number CN104624707A discloses a production process for ultra-fine copper wires of upper oxygen-free copper rod-drawing-annealing-drawing, but the copper rods drawn by this process have many defects such as looseness and shrinkage holes, which are easy to cause wire breaking during the subsequent ultra-fine wire drawing, and the rate of the upper copper rod is 2-3m / min, and the production efficiency is low. The patent document number CN102886390A discloses a production process for ultrafine copper wire, which is upper oxygen-free copper rod-extrusion-drawing-annealing-drawing. Although the added extrusion process reduces internal hole defects to a certain extent, cold deformation may introduce new defects, resulting in subsequent ultrafine wire breakage. Moreover, the added process makes the entire production process complicated, and the prepared copper wire has not undergone final treatment, and the elongation is obviously low. Summary of the invention

[0004] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide an ultra-fine copper wire with high production efficiency, low wire breakage rate and high elongation and a production method thereof.

[0005] To achieve the above object, in a first aspect of the present invention, the present invention provides a method for producing an ultrafine copper wire, the production method comprising the following steps:

[0006] (1) Continuous casting and rolling of copper rods: the electrolytic copper plate is melted, slag removed and purified to obtain molten copper, which is then continuously cast to obtain ingots, which are then continuously rolled, acid-free cleaned and waxed to obtain copper rods;

[0007] (2) Continuous drawing and online annealing: The copper rod is continuously drawn in multiple passes, first in large drawing, then in medium drawing, and in the process of medium drawing, continuous online annealing is performed, and then in small drawing, so as to obtain small-drawn copper wire;

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

[0009] The ultra-fine copper wire production method provided by the present invention has low wire breakage rate and high elongation, and the production process is simple and efficient. Specifically, in the first aspect, the present invention removes slag and purifies the electrolytic copper plate after melting, and can effectively remove oxide impurities, detached furnace materials, mixed materials and other copper slag in the copper liquid during the slag removal process, which can effectively reduce the impurity components in the copper liquid and help to improve the elongation of the ultra-fine copper wire; in the second aspect, the present invention continuously casts and continuously rolls the copper liquid, which can effectively reduce internal defects and reduce the wire breakage rate; in the third aspect, the present invention can effectively isolate the copper rod from the air by acid-free cleaning and waxing after continuous rolling, reduce surface oxidation, and thus reduce the wire breakage rate; in the fourth aspect, the present invention chooses to perform online continuous annealing while pulling, which can be beneficial to restore the plastic processing deformation performance of copper, reduce copper damage, and reduce the wire breakage rate.

[0010] As a preferred embodiment of the production method of the present invention, in the 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 wire 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 obtained ultra-fine copper wire has a higher elongation and a lower wire breakage rate.

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

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

[0014] Preferably, in the step (1), the step of cooling the ingot is further included before the ingot is continuously rolled, and the temperature of the ingot after cooling is 780-850°C.

[0015] As a preferred embodiment of the production method of the present invention, in the step (2), during the drawing process, the steel is firstly 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.

[0016] Preferably, in the step (2), during the drawing process, the steel is firstly drawn to an average diameter of 3 mm, then drawn to an average diameter of 1.13 mm, and then drawn to an average diameter of 0.08-0.16 mm.

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

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

[0019] It should be noted that the present invention has no particular limitation on the emulsion, and any emulsion commonly used in the art can be used. For example, the emulsion can be made of a mixture of drawing crude oil and water.

[0020] In one embodiment, the line speed of the large pull is 900-1200 m / min, and the line speed of the small pull is 1500-2000 m / min. The present invention has no special requirements on the line speeds of the large pull and the small pull, and the purpose of the present invention can be achieved within the range given by the present invention.

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

[0022] The present invention has found that the voltage and speed of online continuous annealing will affect the quality of the copper wire. When the voltage and speed of online continuous annealing are further selected to be within the range given by the present invention, the elongation of the obtained ultra-fine copper wire is lower.

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

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

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

[0026] The present invention has found that annealing after micro-drawing can better improve the elongation of ultra-fine copper wire, especially when the annealing temperature is further selected to be 350-400°C and the speed is 250-300m / min, the comprehensive effect of the obtained ultra-fine copper wire is better.

[0027] As a preferred embodiment of the production method of the present invention, in the 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] As a preferred embodiment of the production method of the present invention, in the step (1), the purity of the electrolytic copper plate is ≥99.99%.

[0030] The requirements for selecting the electrolytic copper plate of the present invention are that the surface is brighter and has no obvious rust, there is basically no copper beans on the surface of the copper plate, and the purity of the copper plate is ≥99.99%; selecting the electrolytic copper plate that meets the above requirements can more effectively ensure the quality of the copper wire and improve the elongation of the 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 the wax used in the wax coating is not particularly limited, and any wax commonly used in the art can be used. Exemplarily, the wax includes paraffin wax.

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

[0034] The curling rate of the continuously cast and rolled low-oxygen copper rod of the present invention is relatively high, which is beneficial to improving production efficiency.

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

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention can effectively reduce impurities in the copper wire and improve the plastic deformation ability of the copper wire by selecting a specific production process of the ultra-fine copper wire, so that the prepared ultra-fine copper wire has a high elongation, a low wire breakage rate during the preparation process, and high production efficiency, which is conducive to actual production applications. Specifically, when the production method of the present invention is used, the weight of the first wire breakage is above 5.1 kg, and the elongation of the obtained ultra-fine copper wire is above 10%. DETAILED DESCRIPTION

[0038] In order to better illustrate the purpose, technical solutions 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 the present invention are all conventional reagents, methods and equipment in the art; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch of raw materials.

[0040] Example 1

[0041] An embodiment of the present invention provides an ultra-fine copper wire, and a production method of the ultra-fine copper wire comprises the following steps:

[0042] (1) Continuous casting and rolling of copper rod: electrolytic copper plates with a purity of 99.99% and no copper beans or rust on the surface are added to a vertical furnace for melting, and the oxygen content in the vertical furnace is controlled. After melting, the copper is filtered and deslagging in 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° C., and then continuous casting of ingots is carried out at a crystallization wheel at a casting rate of 25.6 tons / hour. The ingots are cooled to 800° C. and then continuously rolled on multiple stands. After being rolled to 8 mm copper rods, the surfaces are cleaned without acid, waxed, and then coiled and wound on 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 subjected to multiple continuous drawing, and emulsion is used for cooling and lubrication during drawing. First, it is drawn to an average diameter of 3.0 mm, the drawing speed is 1000 m / min, the emulsion concentration is 11%, the temperature is 35°C, and the pH value is 8; then it is drawn to an average diameter of 1.13 mm, the emulsion concentration is 7%, the temperature is 35°C, and the pH value is 8; while drawing, online annealing is performed, the annealing pressure is 23V, and the annealing speed is 420 m / min; then it is drawn to an average diameter of 0.12 mm, the drawing speed is 1800 m / min, the emulsion concentration is 5%, the temperature is 35°C, and the pH value is 8; and a small-drawn copper wire is obtained;

[0044] (3) Micro-drawing and annealing: The micro-drawn copper wire is micro-drawn to an average diameter of 0.04 mm, the micro-drawing emulsion concentration is 1%, the temperature is 25°C, the pH value is 8, the line speed is 1300 m / min, and then annealed at an annealing temperature of 400°C and a speed of 300 m / min; an ultra-fine copper wire is obtained.

[0045] Example 2

[0046] An embodiment of the present invention provides an ultra-fine copper wire, and a production method of the ultra-fine copper wire comprises the following steps:

[0047] (1) Continuous casting and rolling of copper rod: electrolytic copper plates with a purity of 99.99% and no copper beans or rust on the surface are added to a vertical furnace for melting, and the oxygen content in the vertical furnace is controlled. After melting, the copper is filtered and deslagging in 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° C., and then continuous casting of ingots is carried out at a crystallization wheel at a casting rate of 25.6 tons / hour. The ingots are cooled to 750° C. and then continuously rolled on multiple stands. After being rolled to 8 mm copper rods, the surfaces are cleaned without acid, waxed, and then coiled and wound on 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 subjected to multiple continuous drawing, and emulsion is used for cooling and lubrication during drawing. First, it is drawn to an average diameter of 3.0 mm, the drawing speed is 1000 m / min, the emulsion concentration is 12%, the temperature is 35°C, and the pH value is 8; then it is drawn to an average diameter of 1.13 mm, the emulsion concentration is 8%, the temperature is 35°C, and the pH value is 8; while drawing, online annealing is performed, the annealing pressure is 23V, and the annealing speed is 420 m / min; then it is drawn to an average diameter of 0.08 mm, the drawing speed is 1800 m / min, the emulsion concentration is 4%, the temperature is 35°C, and the pH value is 8; and a small-drawn copper wire is obtained;

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

[0050] Example 3

[0051] An embodiment of the present invention provides an ultra-fine copper wire, and a production method of the ultra-fine copper wire comprises the following steps:

[0052] (1) Continuous casting and rolling of copper rods: electrolytic copper plates with a purity of 99.99% and no copper beans or rust on the surface are added to a vertical furnace for melting, and the oxygen content in the vertical furnace is controlled. After melting, the copper is filtered and deslagging in 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° C., and then continuous casting of ingots is carried out at a crystallization wheel at a casting rate of 25.6 tons / hour. The ingots are cooled to 850° C. and then continuously rolled on multiple stands. After being rolled to 8 mm copper rods, the surfaces are cleaned without acid, waxed, and then coiled and wound on 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 subjected to multiple continuous drawing, and emulsion is used for cooling and lubrication during drawing. First, it is drawn to an average diameter of 3.0 mm, the drawing speed is 1000 m / min, the emulsion concentration is 10%, the temperature is 33°C, and the pH value is 8; then it is drawn to an average diameter of 1.13 mm, the emulsion concentration is 6%, the temperature is 37°C, and the pH value is 8; while drawing, online annealing is performed, the annealing pressure is 22V, and the annealing speed is 400 m / min; then it is drawn to an average diameter of 0.16 mm, the drawing speed is 1800 m / min, the emulsion concentration is 6%, the temperature is 35°C, and the pH value is 8; and a small-drawn copper wire is obtained;

[0054] (3) Micro-drawing and annealing: The micro-drawn copper wire is micro-drawn to an average diameter of 0.05 mm, the micro-drawing emulsion concentration is 0.5%, the temperature is 20°C, the pH value is 8, the line speed is 1850 m / min, and then annealed at an annealing temperature of 350°C and a speed of 250 m / min; an ultra-fine copper wire is obtained.

[0055] Example 4

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

[0057] Example 5

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

[0059] Example 6

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

[0061] Example 7

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

[0063] Example 8

[0064] The embodiment of the present 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 speed of online continuous annealing is 380 m / min.

[0065] Example 9

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

[0067] Example 10

[0068] The embodiment of the present 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 the micro-drawing is 2000 m / min.

[0069] Embodiment 11

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

[0071] Example 12

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

[0073] Example 13

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

[0075] Embodiment 14

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

[0077] Comparative Example 1

[0078] The comparative example of the present 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), continuous annealing is performed online while drawing.

[0079] Comparative Example 2

[0080] The comparative example of the present 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 molten copper flows into the holding furnace and the tundish without slag removal and purification after melting.

[0081] Effect example

[0082] The effect examples of the present 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 first wire break: The weight at the first wire break automatically recorded by the micro-drawing machine;

[0084] 2. Elongation: obtained by testing with a small mechanical testing machine, which is the percentage of the displacement of the copper wire before it breaks and the initial gauge length;

[0085] The obtained 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 Embodiment 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 Embodiment 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] It can be seen from Table 1 that the ultrafine copper wire prepared by the technical solution provided by the present invention has excellent elongation and low wire breakage rate. The weight of the first wire breakage in the preparation process is large; the weight of the first wire breakage is above 5.1 kg, and the elongation is above 10%;

[0089] It can be seen from Examples 1 and 4-14 that the parameters in the production method provided by the present invention affect the performance of the ultra-fine copper wire. When the parameters are further selected within the preferred range of the present invention, the comprehensive performance of the obtained product is better; specifically, the first wire breaking weight is above 7.5 kg, and the elongation is above 15%;

[0090] It can be seen from Example 1 and Comparative Example 1 that when online continuous annealing is not performed during medium drawing but online continuous annealing is performed during large drawing, the obtained ultra-fine copper wire cannot achieve the effect of the present invention; it can be seen from Example 1 and Comparative Example 2 that when slag removal is not performed after melting, the obtained ultra-fine copper wire cannot achieve the purpose of the present invention.

[0091] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for producing ultrafine copper wire, characterized in that: The production method comprises the following steps: (1) Continuous casting and rolling of copper rods: the electrolytic copper plate is melted, slag removed and purified to obtain molten copper, which is then continuously cast to obtain ingots, which are then continuously rolled, acid-free cleaned and waxed to obtain copper rods; (2) Continuous drawing and online annealing: The copper rod is continuously drawn in multiple passes, first in large drawing, then in medium drawing, and in the process of medium drawing, continuous online annealing is performed, and then in small drawing, so as to obtain small-drawn copper wire; (3) Micro-drawing and annealing: The small-drawn copper wire is micro-drawn to an average diameter of 0.03-0.05 mm and then annealed to obtain an ultra-fine copper wire.

2. The production method according to claim 1, characterized in that In the step (1), the oxygen content of the copper rod is 0.017-0.023%.

3. The production method according to claim 1, characterized in that In the step (1), the casting temperature is 1115-1125°C.

4. The production method according to claim 1, characterized in that In the step (2), during the drawing process, the steel sheet is firstly 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.

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

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

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

5.

6. The production method according to claim 1, characterized in that: In the step (2), the voltage of the online continuous annealing is 20-25V and the speed is 400-450m / min.

7. The production method according to claim 1, characterized in that: In the step (3), an emulsion is used for cooling and lubrication during micro-pulling, and the emulsion concentration is 0.5-2%, the temperature is 20-30° C., and the pH value is 7.5-8.5; And / or, the line speed during micro-drawing is 1000-1900 m / min.

8. The production method according to claim 1, characterized in that: In the step (3), the annealing temperature is 350-400° C. and the annealing speed is 250-300 m / min.

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

10. An ultrafine copper wire, characterized in that: The ultrafine copper wire is prepared by the production method according to any one of claims 1 to 9.