A process control method for improving electrical performance of soft copper stranded wire, soft copper stranded wire and cable

Abstract

The present invention discloses a process control method for improving the electrical performance of soft copper stranded wire, soft copper stranded wire and cable, and belongs to the technical field of wire and cable manufacturing. The method comprises the following steps: drawing an oxygen-free copper rod to obtain a copper monofilament; wherein the elongation at break of the copper monofilament is controlled at 30%-35%; a plurality of copper monofilaments are stranded to obtain a plurality of groups of strands; a plurality of groups of strands are re-twisted to obtain a soft copper stranded wire; wherein the twisting pitch-diameter ratio of the inner layer of the soft copper stranded wire in two adjacent layers of soft copper stranded wire is greater than the twisting pitch-diameter ratio of the outer layer of the soft copper stranded wire; the re-twisting pitch-diameter ratio of the strands of the soft copper stranded wire ranges from 50 times to 12 times from the inside to the outside; and the inner hole size of the stranding mold during the re-twisting process is 90%-97% of the nominal twisting outer diameter value. The method can effectively improve the electrical performance of the soft copper stranded wire, improve the production efficiency of the soft copper stranded wire products, and reduce production costs.

Description

Technical Field

[0001] The invention belongs to the technical field of wire and cable manufacturing, and specifically relates to a process control method for improving the electrical performance of soft copper stranded wire, a soft copper stranded wire and a cable. Background Art

[0002] According to the technical requirements for soft copper stranded wire and tinned soft copper stranded wire products specified in the standards GB / T12970.2-2009 "Electrical soft copper stranded wire Part 2 soft copper stranded wire" and GB / T3956-2008 "Conductors of cables", the existing process flow is basically as follows: first, an oxygen-free copper rod with a diameter of φ8.0mm is used for wire drawing on a wire drawing device to draw a finer copper monofilament (diameter not exceeding φ1.0mm) as required by the process or standard, and then multiple copper monofilaments are twisted together for the first time according to a certain twisting pitch diameter ratio. Common strands are made of 7-45 copper monofilaments. Finally, the twisted multiple strands are twisted together for a second time according to a certain twisting pitch diameter ratio, which is also called re-twisting, to complete the twisting of the soft copper stranded wire product.

[0003] According to the technical requirements of the standard GB / T3953-2024 "Electrical Round Copper Wire", the existing monofilament elongation at break only needs to meet the technical requirements of the standard ≥25% to meet the standard, but the elongation at break requirement range is too wide. If only the elongation at break of ≥25% is met, it is easy to affect the electrical performance and softness of the finished soft copper stranded wire after multiple production processes. At the same time, in the existing soft copper stranded wire stranding process, the outer layer's multiple twisting pitch-diameter ratio is usually greater than the inner layer. The excessively large twisting pitch-diameter ratio of each layer will lead to insufficient stranding tightness of the stranded wire, loose stranding as a whole, reduced contact surface between the internal copper monofilaments, and increased contact wire resistance; while the too small twisting pitch-diameter ratio will also result in a small contact surface between the copper monofilaments inside the stranded wire, and the unnecessary electrical performance loss of the copper monofilaments will be aggravated due to the increased bending deformation of the copper monofilaments, which will ultimately lead to the failure to control the material cost of the copper stranded wire while also reducing the electrical performance of the copper stranded wire.

[0004] Although the existing production process in the cable processing industry focuses on improving the electrical properties of copper stranded wire, there is a lack of in-depth research on the stranding process of copper stranded wire. This leads to the disadvantages of high material cost, unsatisfactory electrical properties of the final product and low production efficiency. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a process control method, soft copper stranded wire and cable for improving the electrical performance of soft copper stranded wire, thereby improving the electrical performance of soft copper stranded wire, improving the production efficiency of soft copper stranded wire products and reducing production costs.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a process control method for improving the electrical performance of soft copper stranded wire, comprising the following steps: The oxygen-free copper rod is subjected to wire drawing to obtain copper monofilaments; wherein the elongation at break of the copper monofilaments is controlled at 30%-35%, which can effectively ensure that the copper monofilaments still have good electrical properties after going through multiple processes to become finished products; A plurality of copper monofilaments are twisted into strands to obtain a plurality of strands; A plurality of groups of strands are re-twisted to obtain soft copper stranded wires; wherein, the twisting pitch diameter ratio of the inner layer of soft copper stranded wires in two adjacent layers of soft copper stranded wires is greater than the twisting pitch diameter ratio of the outer layer of soft copper stranded wires; the re-twisting pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 times to 12 times from the inside to the outside; the inner hole size of the twisting die during the re-twisting process is 90%-97% of the nominal twisting outer diameter value (according to the size of the twisting diameter during the re-twisting process, the die size ratio fluctuates in this range, and the larger the twisting diameter, the lower the percentage). If the die size ratio is too large, it is easy to cause the stranded wire to be insufficiently tight, and if it is too small, it will cause quality problems such as jumpers and broken wires on the surface of the stranded wire.

[0007] In one embodiment, the strand pitch diameter ratio of the strands during the stranding process is 13 to 15 times. The strand pitch diameter ratio should not be too small or too large. If it is too small, it will waste material costs and aggravate the cold deformation of the copper monofilament, resulting in unnecessary electrical performance loss; if it is too large, it will easily cause poor quality problems such as jumpers or looseness on the surface of the stranded wire in the next re-twisting process.

[0008] In one embodiment, during the re-twisting process, the re-twisting pitch ratio of each layer of the soft copper stranded wire gradually decreases from the inner layer to the outer layer.

[0009] In one embodiment, a three-stage online annealing treatment technology is simultaneously used during the wire drawing process, and the annealing temperature is increased by increasing the voltage to produce a copper single wire with a breaking elongation controlled at 30%-35%.

[0010] In one embodiment, the diameter of the copper monofilament is less than 1.0 mm.

[0011] In one embodiment, the number of copper monofilaments constituting the strand is usually 7-45, and the 7-45 copper monofilaments are twisted according to a certain twisting pitch ratio (13 times-15 times).

[0012] The present invention also provides a soft copper stranded wire produced by the process control method for improving the electrical properties of the soft copper stranded wire mentioned above, comprising a strand, wherein the strand comprises a plurality of twisted copper monofilaments, a plurality of groups of the strands are distributed circumferentially around the central axis of the soft copper stranded wire from the inner layer to the outer layer and are re-twisted layer by layer in sequence, the twisted pitch diameter ratio of the copper monofilaments in the strand is 13 times to 15 times, the re-twisted pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 times to 12 times from the inside to the outside, and the re-twisted pitch diameter ratio of each layer decreases successively from the inner layer to the outer layer.

[0013] In one embodiment, the elongation at break of the copper monofilament is controlled at 30%-35%.

[0014] The present invention also provides a cable, comprising the above-mentioned soft copper stranded wire, wherein the outside of the soft copper stranded wire is sequentially wrapped with an insulating layer, a non-metallic wrapping layer, a shielding layer, an armor layer and a sheath layer.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a process control method for improving the electrical performance of soft copper stranded wire. The method optimizes the electrical performance of soft copper stranded wire, improves production efficiency and reduces production costs by controlling the elongation at break of copper monofilaments, the stranding pitch ratio of stranded wires, the change of the stranding pitch ratio during the re-twisting process and the ratio of the inner hole size of the stranding mold. First, the elongation at break of the copper monofilaments is controlled within the range of 30%-35%, which not only avoids the problem of increased resistivity due to cold deformation of the copper monofilaments in the multi-process twisting process caused by too small elongation at break, and the problem of affecting the softness of the copper stranded wire products, but also prevents the problem of excessive elongation at break, excessive softening of the monofilaments, and easy change of the monofilament diameter during the multi-process twisting process of the copper monofilaments, which affects the electrical performance of the finished copper stranded wire products. Secondly, in the re-twisting process, the stranding pitch ratio is gradually reduced from the inside to the outside, and the innermost layer stranding pitch ratio is up to 50 times. This design effectively increases the contact surface between the copper monofilaments, reduces the contact resistance, and thus improves the DC resistance performance of the soft copper stranded wire. At the same time, it can solve the speed limitation of production equipment and greatly improve production efficiency. In addition, the closer to the outermost layer, the smaller the twisting pitch-diameter ratio is. The outermost pitch-diameter ratio is up to 12 times, which can effectively solve the problem of insufficient tightness of soft copper stranded wire. Furthermore, the design of large twisting pitch-diameter ratio improves production efficiency and can effectively reduce material costs (the larger the twisting pitch-diameter ratio, the lower the amount of stranded wire or copper monofilament material used per unit length of the twisted soft copper stranded wire product). Finally, by using a twisting die with a size ratio of 90%-97% based on the nominal twisted outer diameter value, the outer diameter of the soft copper stranded wire is reduced, the twisting tightness is further improved, the contact surface between the copper monofilaments is increased, the contact resistance is reduced, and the DC resistance performance is improved.

[0016] Furthermore, during the stranding process, the strand pitch diameter ratio is controlled at 13-15 times to prevent the strands from becoming loose and affecting the surface quality of the strands during re-twisting, such as wire skipping and wire breakage, thereby improving the overall product quality.

[0017] Furthermore, by optimizing the mold ratio to reduce the outer diameter of the soft copper stranded wire, the material cost of all subsequent processes can be effectively reduced, such as the use of metal or plastic materials such as insulation extrusion, non-metallic tape wrapping, metal armor, metal shielding, and sheath extrusion. This cost reduction is achieved by optimizing the stranding tightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a typical cross-sectional structure of a soft copper stranded wire product in the prior art. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] DC resistance is a physical quantity that measures the conductivity of a material. It reflects the material's ability to hinder the movement of electrons or current under a potential difference, per unit length and per unit cross-sectional area. For soft copper stranded wire, its DC resistance refers to the DC resistance value of the stranded wire under a unit length (usually 1 meter) and per unit cross-sectional area (usually 1 square millimeter) at 20°C. This performance parameter ensures the good conductivity of soft copper stranded wire in electrical equipment and electronic appliances or component wiring.

[0022] DC resistance is an important indicator to measure the conductivity of stranded wire. In the wiring of electrical equipment and electronic appliances or components, it is necessary to ensure that the conductivity of the stranded wire is good to ensure the normal transmission of current. In the process of power transmission and distribution, if the resistance of the stranded wire is too large, it will generate too much heat, which may cause the stranded wire to burn or cause fire and other safety accidents. Therefore, it is necessary to strictly control the DC resistance of the stranded wire to ensure its safe use.

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings: Taking TJR1-95 as an example, the typical cross-sectional structure of the existing soft copper stranded wire product is shown in Figure 1. Figure 1 As shown, its structure is 37×7 / 0.68.

[0024] The present invention provides a process control method for improving the electrical performance of soft copper stranded wire, and the specific process control method comprises the following steps: The oxygen-free copper rod is subjected to wire drawing to obtain copper monofilaments; wherein the elongation at break of the copper monofilaments is controlled at 30%-35%, which can effectively ensure that the copper monofilaments still have good electrical properties after going through multiple processes to become finished products; A plurality of copper monofilaments are twisted into strands to obtain a plurality of strands; A plurality of groups of strands are re-twisted to obtain soft copper stranded wires; wherein, the twisting pitch diameter ratio of the inner layer of soft copper stranded wires in two adjacent layers of soft copper stranded wires is greater than the twisting pitch diameter ratio of the outer layer of soft copper stranded wires; the re-twisting pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 times to 12 times from the inside to the outside; the inner hole size of the twisting die during the re-twisting process is 90%-97% of the nominal twisting outer diameter value (according to the size of the twisting diameter during the re-twisting process, the die size ratio fluctuates in this range, and the larger the twisting diameter, the lower the percentage). If the die size ratio is too large, it is easy to cause the stranded wire to be insufficiently tight, and if it is too small, it will cause quality problems such as jumpers and broken wires on the surface of the stranded wire.

[0025] The above process control method improves the elongation at break performance. During the monofilament drawing process, the monofilament wire diameter should be drawn according to the standard or process requirements. Online annealing is required during the monofilament drawing process, so that the elongation at break of the copper monofilament not only meets the technical requirements of the standard ≥25%. Combined with the production status of the equipment, the elongation at break is controlled at 30%≤L≤35%. When the elongation at break is too small, the monofilament resistivity increases due to multiple cold deformations during stranding and re-twisting due to factors such as guide wheels, tension, and torsion, which affects the DC resistance performance of the finished product; and when the elongation at break is too large, the monofilament wire diameter changes easily due to excessive softening during stranding and re-twisting, which also affects the DC resistance performance of the finished stranded wire.

[0026] Furthermore, during the stranding process, the strand pitch diameter ratio is controlled at 13-15 times to prevent the strands from becoming loose and affecting the surface quality of the strands during re-twisting, such as wire skipping, wire breakage and other quality problems.

[0027] In addition, during the re-twisting process, due to the different specifications of the soft copper stranded wire, the single-filament combination structure ranges from 2 to 5 layers. However, due to the influence of the stranding pitch-diameter ratio on the DC resistance, after the test, the stranding pitch-diameter ratio should be changed from large to small from the inside to the outside. The stranding pitch-diameter ratio ranges from 50 times to 12 times. The stranding pitch-diameter ratio of the two adjacent layers should be greater for the inner layer than for the outer layer. The design of this larger stranding pitch-diameter ratio of the inner layer can improve certain production efficiency, and at the same time can effectively increase the contact surface between the single wires, which is helpful to improve the DC resistance performance of the soft copper stranded wire. At the same time, the larger pitch-diameter ratio design can effectively reduce the material consumption and save production costs.

[0028] Furthermore, during the re-twisting process, due to the different specifications of the soft copper stranded wire, the single-filament combination structure ranges from 2 to 5 layers. According to the process design calculation, there is a nominal stranding outer diameter. Generally, a stranding die with the same inner hole size is configured according to this calculated value. However, the traditional configuration method of the inner hole size of the stranding die cannot meet the requirements of the present invention for the stranding tightness and the reduction of the outer diameter size. Therefore, the present invention adjusts the ratio of the inner hole size of the stranding die, that is, the stranding die is twisted at a size ratio of 90% to 97% on the basis of the nominal stranding outer diameter value. This ratio method has two functions. The first is to reduce the outer diameter size of the soft copper stranded wire so that it is not easy to loosen during circulation and use, and because of the reduction of its outer diameter size, the material cost of all subsequent processes (such as insulation extrusion, non-metallic strip wrapping, metal armor, metal shielding, sheath extrusion, etc.) is reduced; the second is to improve the stranding tightness of the soft copper stranded wire, and at the same time, it can increase the contact surface between the single wires in the soft copper stranded wire, reduce the contact resistance between the single wires, and thus improve the DC resistance performance of the soft copper stranded wire.

[0029] The overall production process of the product from wire drawing to stranding remains unchanged compared to the original process. The production equipment mainly involves wire drawing annealing equipment, wire bundling equipment, and wire stranding equipment. The diameter of the single wire in the above process control method is less than 1.0mm, and the number of single wires in the strand is usually 7-45.

[0030] The present invention also provides a soft copper stranded wire produced by the process control method for improving the electrical properties of the soft copper stranded wire mentioned above, the soft copper stranded wire comprising a strand, the strand comprising a plurality of twisted copper monofilaments, the plurality of strands being distributed circumferentially around the central axis of the soft copper stranded wire from the inner layer to the outer layer and being re-twisted layer by layer, the twisted pitch diameter ratio of the copper monofilaments in the strand is 13 to 15 times, the re-twisted pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 to 12 times from the inside to the outside, and the re-twisted pitch diameter ratio of each layer decreases from the inner layer to the outer layer; the elongation at break of the copper monofilaments is controlled at 30% to 35%.

[0031] The present invention also provides a cable comprising the above-mentioned soft copper stranded wire, wherein the outside of the soft copper stranded wire is sequentially wrapped with an insulating layer, a non-metallic wrapping layer, a shielding layer, an armor layer and a sheath layer.

[0032] In a specific embodiment 1, a process control method for improving the electrical performance of soft copper stranded wire is provided, and a test comparison is carried out using the model specification TJR1-95 as an example, as follows: S1: φ8.0 oxygen-free copper rod material is used on the wire drawing equipment for multiple wire drawing and online annealing to produce copper monofilament with a breaking elongation of 30%-35%; S2: Use the wire bundling equipment to perform a stranding operation according to the process or product structure requirements in the standard to produce multiple strands. During the stranding process, the strand pitch-diameter ratio is controlled at 13-15 times; S3: Use stranding equipment to perform secondary re-twisting according to the process or product structure requirements in the standard to produce soft copper stranded wire, the inner layer re-twisting pitch diameter ratio of the soft copper stranded wire is 50 times, the second outer layer re-twisting pitch diameter ratio is 18 times, and the outermost layer re-twisting pitch diameter ratio is 12 times. Among them, the inner hole size of the stranding die during the re-twisting process corresponds to 97%, 94%, and 90% of the nominal stranding outer diameter value of the inner and outer layers.

[0033] In a comparative example 1, a process control method for improving the electrical performance of soft copper stranded wire is provided, which is as follows: S1: φ8.0 oxygen-free copper rod material is used on the wire drawing equipment for multiple wire drawing and online annealing to produce copper monofilament with a breaking elongation of 25%-27%; S2: Use the wire bundling equipment to perform a stranding operation according to the product structure requirements in the standard to produce multiple strands. During the stranding process, the strand pitch ratio is controlled to be 13-15 times; S3: Use stranding equipment to perform secondary re-twisting according to the product structure requirements in the standard to produce soft copper stranded wire. The inner layer re-twisting pitch diameter ratio of the soft copper stranded wire is 50 times, the second outer layer re-twisting pitch diameter ratio is 18, and the outermost layer re-twisting pitch diameter ratio is 12 times. Among them, the inner hole size of the stranding die during the re-twisting process corresponds to 97%, 94%, and 90% of the nominal stranding outer diameter values ​​of the inner and outer layers.

[0034] In a comparative embodiment 2, a process control method for improving the electrical performance of soft copper stranded wire is provided, which is as follows: S1: φ8.0 oxygen-free copper rod material is used on the wire drawing equipment for multiple wire drawing and online annealing to produce copper monofilament with a breaking elongation of 30%-35%; S2: Use the wire bundling equipment to perform a stranding operation according to the product structure requirements in the standard to produce multiple strands. During the stranding process, control the stranding pitch diameter ratio to 20-25 times (adjust the test within the standard technical requirements); S3: Use stranding equipment to perform secondary re-twisting according to the product structure requirements in the standard to produce soft copper stranded wire. The inner layer re-twisting pitch diameter ratio of the soft copper stranded wire is 50 times, the second outer layer re-twisting pitch diameter ratio is 18, and the outermost layer re-twisting pitch diameter ratio is 12 times. Among them, the inner hole size of the stranding die during the re-twisting process corresponds to 97%, 94%, and 90% of the nominal stranding outer diameter values ​​of the inner and outer layers.

[0035] In a comparative embodiment 3, a process control method for improving the electrical performance of soft copper stranded wire is provided, which is as follows: S1: φ8.0 oxygen-free copper rod material is used on the wire drawing equipment for multiple wire drawing and online annealing to produce copper monofilament with a breaking elongation of 30%-35%; S2: Use the wire bundling equipment to perform a stranding operation according to the product structure requirements in the standard to produce multiple strands. During the stranding process, the strand pitch ratio is controlled to be 13-15 times; S3: Use stranding equipment to perform secondary re-twisting according to the product structure requirements in the standard to produce soft copper stranded wire. The inner layer re-twisting pitch diameter ratio of the soft copper stranded wire is 50 times, the second outer layer re-twisting pitch diameter ratio is 18, and the outermost layer re-twisting pitch diameter ratio is 12 times. Among them, the inner hole size of the stranding die during the re-twisting process corresponds to 100%, 100%, and 100% of the nominal stranding outer diameter values ​​of the inner and outer layers.

[0036] In a comparative example 4, a process control method for improving the electrical performance of soft copper stranded wire is provided, as follows: S1: φ8.0 oxygen-free copper rod material is used on the wire drawing equipment for multiple wire drawing and online annealing to produce copper monofilament with a breaking elongation of 30%-35%; S2: Use the wire bundling equipment to perform a stranding operation according to the product structure requirements in the standard to produce multiple strands. During the stranding process, the strand pitch ratio is controlled to be 13-15 times; S3: The stranding equipment is used to perform secondary re-twisting according to the product structure requirements in the standard to produce soft copper stranded wire. The re-twisting pitch diameter ratio of the inner layer of the soft copper stranded wire is 20 times, the re-twisting pitch diameter ratio of the second outer layer is 16, and the re-twisting pitch diameter ratio of the outermost layer is 13 times. Among them, the inner hole size of the stranding die during the re-twisting process corresponds to 97%, 94%, and 90% of the nominal stranding outer diameter values ​​of the inner and outer layers.

[0037] Resistance test The above-mentioned Example 1 and Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were respectively tested for the influence of the elongation at break of the single wire on the electrical properties of the product, the influence of the strand twisting pitch diameter ratio on the surface quality of the re-twisting, the influence of the re-twisting mold ratio on the electrical properties of the product, and the influence of the re-twisting pitch diameter ratio on the production efficiency and the electrical properties of the product. The specific test process is as follows: The DC resistance test is based on Ohm's law, which states that resistance (R) is equal to the ratio of voltage (U) to current (I) (R=U / I). By using a professional resistance measuring instrument, the DC resistance of a conductor can be calculated after applying voltage to both ends of the conductor.

[0038] The specific test method of DC resistance test is as follows: Prepare the specimen: Prepare conductor samples that meet the requirements, usually 1.5-2.0 meters. Make sure the sample surface is clean, free of attachments, oil stains and oxide layers. If necessary, use alcohol or dilute hydrochloric acid to clean it.

[0039] Install the specimen: Straighten the processed sample and install it into the conductor resistance fixture. Make sure the sample is neither loose nor tight in the fixture to ensure the accuracy of the measurement.

[0040] Connect your device: Correctly connect the two current terminals and two potential terminals of the conductor fixture to the wiring terminals of the DC resistance tester.

[0041] Set the test parameters: According to the resistance value range of the sample, select the appropriate test range and magnification. Perform mechanical and electrical zeroing to ensure that the pointer or display of the tester is at zero.

[0042] Start testing: Start the tester and begin measuring the DC resistance of the sample. Record the resistance value displayed by the tester and make multiple measurements as needed to obtain the average value.

[0043] Data processing: Convert the measured resistance value to the standard resistance value at 20℃ for comparison with the national standard.

[0044] End of test: Turn off the tester and unload the sample to be tested.

[0045] The unit weight test method is as follows: Sampling: Length 1.5-2.0 m; Test method: First, straighten the sample and use the same length measuring tool (tape measure, ruler, etc.) to measure its exact length, accurate to millimeters; then place the sample on the same weight measuring instrument (which has been reset to zero in advance) and weigh it, accurate to grams; finally, convert the units and calculate the unit weight.

[0046] The data of Example 1 and Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are shown in the following table:

[0047] Through the comparison of the above test data, it can be seen that the process control method provided by the present invention can effectively improve the electrical performance of soft copper stranded wire, reduce the product diameter, reduce material costs, and improve product production efficiency.

[0048] The present invention is formulated for soft copper stranded wire products. According to the process control method, the DC resistance of soft copper stranded wire products can be effectively reduced and the surface quality unqualified rate can be reduced, and the problems of high material cost and low production efficiency can be solved. According to production statistics, after the process is adjusted, the production speed is increased by more than 10%, and the copper material cost is reduced by 1%-2%. If calculated based on the annual output value of a company producing 1000t of this type of conductor, the annual copper material savings are about 8 million yuan.

[0049] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A process control method for improving the electrical performance of soft copper stranded wire, characterized in that: The following steps are involved: The oxygen-free copper rod is subjected to wire drawing to obtain a copper monofilament; wherein the elongation at break of the copper monofilament is controlled at 30%-35%; A plurality of copper monofilaments are twisted into strands to obtain a plurality of strands; A plurality of groups of strands are re-twisted to obtain soft copper stranded wires; wherein, the twisting pitch diameter ratio of the inner layer of soft copper stranded wires in two adjacent layers of soft copper stranded wires is greater than the twisting pitch diameter ratio of the outer layer of soft copper stranded wires; the re-twisting pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 times to 12 times from the inside to the outside; and the inner hole size of the twisting die during the re-twisting process is 90% to 97% of the nominal twisting outer diameter value.

2. The process control method for improving the electrical performance of soft copper stranded wire according to claim 1, characterized in that: During the strand twisting process, the strand pitch diameter ratio is 13 to 15 times.

3. The process control method for improving the electrical performance of soft copper stranded wire according to claim 1, characterized in that: During the re-twisting process, the re-twisting pitch diameter ratio of each layer of the soft copper stranded wire gradually decreases from the inner layer to the outer layer.

4. The process control method for improving the electrical performance of soft copper stranded wire according to claim 1, characterized in that: A three-stage online annealing process is also used during the wire drawing process to produce a copper single wire with a breaking elongation controlled at 30%-35%.

5. The process control method for improving the electrical performance of soft copper stranded wire according to claim 1, characterized in that: The diameter of the copper monofilament is less than 1.0 mm.

6. The process control method for improving the electrical performance of soft copper stranded wire according to claim 1, characterized in that: The strands are formed by twisting 7 to 45 copper monofilaments.

7. A soft copper stranded wire produced by the process control method for improving the electrical properties of soft copper stranded wire according to any one of claims 1 to 6, characterized in that: The invention comprises a stranded wire, wherein the stranded wire comprises a plurality of twisted copper monofilaments, wherein the plurality of groups of the stranded wires are circumferentially distributed around the central axis of the soft copper stranded wire from the inner layer to the outer layer and are twisted layer by layer in sequence, wherein the twisted pitch diameter ratio of the copper monofilaments in the stranded wire is 13 to 15 times, and the twisted pitch diameter ratio of the strands of the soft copper stranded wire ranges from 50 to 12 times from the inner layer to the outer layer, and the twisted pitch diameter ratio of each layer decreases in sequence from the inner layer to the outer layer.

8. The soft copper stranded wire according to claim 7, characterized in that: The elongation at break of the copper monofilament is controlled at 30%-35%.

9. A cable, characterized in that: The cable comprises the soft copper stranded wire as claimed in any one of claims 7 to 8.

10. The cable according to claim 9, characterized in that The exterior of the soft copper stranded wire is sequentially wrapped with an insulating layer, a non-metallic wrapping layer, a shielding layer, an armor layer and a sheath layer.

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