Preparation process of energy-saving aluminum alloy cable

Abstract

The invention relates to a preparation process of an energy-saving aluminum alloy cable, and belongs to the technical field of cables. According to the method, an aluminum ingot with the purity larger than 99.85 wt% is used for smelting a high-conductivity aluminum alloy rod, Si, Fe, B and trace Cr, Mn, V and Ti in a specific proportion are added, and the aluminum rod is obtained through continuous casting and continuous rolling after refining; the cable is prepared by the following steps of: performing wire drawing to form monofilaments, twisting the monofilaments into a compressed conductor with a section of 230-250mm, wrapping a semi-conductive belt, synchronously extruding a conductor shielding layer, an XLPE insulating layer and an insulation shielding layer, coating a soft copper belt, and extruding a PVC outer protective layer. The process obviously reduces the direct-current resistance of the cable, and improves the conductivity and the energy-saving property.

Description

Technical Field

[0001] The invention belongs to the technical field of cables and relates to a preparation process of an energy-saving aluminum alloy cable. Background Art

[0002] Energy-saving aluminum alloy cables, due to their lightweight, high conductivity, corrosion resistance, and environmentally friendly properties, have become a key alternative to traditional copper cables. Aluminum alloy cables not only offer low density and superior corrosion resistance, but also significantly reduce material and transportation costs while meeting power transmission requirements. Furthermore, aluminum alloy materials have a high recycling rate, aligning with the principles of sustainable development and environmental protection. With the widespread use of renewable energy and increasing electricity demand, the requirements for transmission lines are becoming increasingly stringent, and the application prospects of energy-saving aluminum alloy cables are promising.

[0003] As transmission capacity increases, the current carried by cables also increases. The cable's inherent resistance can lead to significant transmission losses, hindering the efficient transmission of power. To meet the demands of modern industrial and civilian power systems, reducing transmission losses has become a key research and development focus. Traditional aluminum-core cables, while advantageous in weight and cost, suffer from higher line losses due to aluminum's lower conductivity than copper. Therefore, continuous technical improvements in the conductivity of aluminum alloy cables are needed to reduce losses during power transmission and thereby improve overall energy efficiency.

[0004] While traditional aluminum alloy cables offer advantages over copper cables in terms of cost and weight, their lower conductivity leads to higher line losses. Some technologies attempt to compensate for this conductivity deficiency by increasing the conductor's cross-sectional area, but this often results in increased cable weight, negating the lightweight advantage. Furthermore, improper impurity control and improper alloy composition during production can further reduce the cable's conductivity. Therefore, improving the purity of aluminum alloy materials and optimizing the alloy composition ratio, combined with more advanced manufacturing processes, is expected to reduce resistivity while maintaining the cable's mechanical properties and durability, thereby achieving more energy-efficient and efficient power transmission. Summary of the Invention

[0005] The object of the present invention is to provide a preparation process for an energy-saving aluminum alloy cable, which does not increase the cable cross-section and achieves higher transmission capacity and lower line loss.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A preparation process for an energy-saving aluminum alloy cable comprises the following steps: (1) A high-conductivity aluminum alloy rod is prepared by melting an aluminum ingot with a purity of ≥99.85wt%, adding the following alloy components: Si 0.025-0.035wt%, Fe 0.05-0.12wt%, B 0.03-0.05wt%, Cr, Mn, V and Ti ≤ 0.02wt%, and controlling the remaining impurity elements to ≤ 0.015wt%, with the balance being Al. After melting, 0.15-0.20wt% of a refining agent is added for refining, and after standing, the aluminum rod is prepared by continuous casting and rolling process; (2) drawing the aluminum rod obtained in step (1) into a monofilament with a diameter of 2.8-2.9 mm; (3) 37 strands of the monofilaments prepared in step (2) are twisted into a conductor; (4) wrapping the conductor obtained in step (3) around a semi-conductive tape, and then simultaneously forming a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the surface of the semi-conductive tape through a three-layer co-extrusion process; (5) wrapping a soft copper tape around the surface of the insulating shielding layer obtained in step (4); (6) The polyvinyl chloride sheath material is coated on the surface of the soft copper strip obtained in step (5) through an extrusion process to form an outer protective layer.

[0007] In this application, low impurity control can reduce the scattering effect of impurity atoms on electrons, making the resistivity close to that of pure aluminum; adding 0.03-0.05wt% B to form high-melting-point TiB2 and VB2 compounds with impurities Ti and V, eliminating grain boundary segregation and improving grain boundary conductivity; the refining temperature of 755-765℃ is higher than the inflection point of the aluminum melt viscosity, ensuring that the refining agent is fully decomposed and adsorbs H2 and Al2O3 inclusions; the tundish temperature of 710-730℃ inhibits the coarsening of the AlB2 phase.

[0008] As a preferred technical solution of the present invention, the refining temperature is 755-765° C.; and the standing time is 30-50 minutes.

[0009] As a preferred technical solution of the present invention, the continuous casting and rolling process is controlled as follows: tundish temperature 710-730°C, rolling entry temperature 550-570°C, rolling temperature 350-400°C, and exit temperature 300-350°C.

[0010] As a preferred technical solution of the present invention, the single-filament resistivity in step (2) is ≤0.027586 Ω·mm² / m.

[0011] As a preferred technical solution of the present invention, the conductor cross-section in step (3) is 230-250 mm², and the compression coefficient is ≥0.90.

[0012] As a preferred technical solution of the present invention, the thickness of the semi-conductive tape in step (4) is 0.1-0.15 mm; and the overlapping wrapping rate is 15% to 20%.

[0013] As a preferred technical solution of the present invention, the thickness of the conductor shielding layer in step (4) is 0.7-0.9 mm; the thickness of the XLPE insulation layer is 4.05-4.6 mm; the thickness of the insulation shielding layer is 0.7-0.9 mm; and the eccentricity of any cross section after the three layers are co-extruded is ≤15%.

[0014] As a preferred technical solution of the present invention, the thickness of the soft copper strip in step (5) is 0.1-0.14 mm; and the overlap rate between the copper strips is 10-20%.

[0015] As a preferred technical solution of the present invention, the thickness of the outer protective layer in step (6) is 1.68-2.2 mm. Furthermore, the energy-saving aluminum alloy cable prepared by the preparation process has a DC resistance of ≤0.1184Ω / km at 20°C.

[0016] Beneficial effects of the present invention: (1) The present invention precisely controls the composition of the aluminum alloy and adds 0.03%-0.05% of the B element to inhibit the growth of the aluminum rod grains, reduce the scattering centers in the conductive channel, optimize the ratio of Si and Fe, and thus improve the conductivity; the total amount of Cr, Mn, V, and Ti is controlled to not exceed 0.02%, avoiding the segregation of transition elements at the grain boundaries and resulting in a decrease in conductivity; and the conductivity of the single wire is improved.

[0017] (2) Through the synergistic effect of the alloy components Si, Fe, B and the rolling process, the tensile strength and elongation of the aluminum rod are improved to meet the bending and installation requirements of the cable; the three-layer co-extruded insulation system is combined with the semi-conductive tape wrapping to ensure uniform distribution of the electric field and reduce the risk of breakdown; the soft copper tape shielding layer enhances electromagnetic compatibility and grounding safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0019] Figure 1 Schematic diagram of the structure of an energy-saving aluminum alloy power cable. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0021] The refining agent involved in the following examples and comparative examples was purchased from Xuzhou Tiancheng Aluminum Co., Ltd. with the product number TC-LJ1.

[0022] Example 1 Please refer to Figure 1 The preparation process of the energy-saving aluminum alloy cable in this embodiment includes the following steps: (1) A high-conductivity aluminum alloy rod was prepared by melting an aluminum ingot with a purity of 99.86wt%, and the alloy components were added: Si 0.025%wt, Fe 0.05%wt, B 0.03%wt, Cr, Mn, V and Ti 0.02wt%. The remaining impurity elements were controlled to 0.015wt%, and the balance was Al. After melting, 0.17wt% of refining agent was added for refining. After standing, the aluminum rod was prepared by continuous casting and rolling process. (2) drawing the aluminum rod obtained in step (1) into a single wire with a diameter of 2.85 mm; (3) 37 strands of the monofilaments prepared in step (2) are twisted into a conductor; (4) wrapping the conductor obtained in step (3) around a semi-conductive tape, and then simultaneously forming a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the surface of the semi-conductive tape through a three-layer co-extrusion process; (5) wrapping a soft copper tape around the surface of the insulating shielding layer obtained in step (4); (6) The polyvinyl chloride sheath material is coated on the surface of the soft copper strip obtained in step (5) through an extrusion process to form an outer protective layer.

[0023] The refining temperature is 760° C. and the standing time is 40 minutes.

[0024] The continuous casting and rolling process is controlled as follows: tundish temperature 720°C, rolling entry temperature 560°C, rolling temperature 375°C, and rolling exit temperature 325°C.

[0025] The conductor cross-section in step (3) is 240 mm² and the compression coefficient is 0.90.

[0026] As a preferred technical solution of the present invention, the thickness of the semi-conductive tape in step (4) is 0.12 mm; and the overlapping wrapping rate is 18%.

[0027] In step (4), the conductor shielding layer has a thickness of 0.8 mm; the XLPE insulation layer has a thickness of 4.3 mm; the insulation shielding layer has a thickness of 0.8 mm; and after the three layers are co-extruded, the eccentricity of any cross section is ≤15%.

[0028] The thickness of the soft copper strip in step (5) is 0.12 mm; the overlap rate between the copper strips is 15%.

[0029] The thickness of the outer protective layer in step (6) is 1.68 mm.

[0030] Example 2 Please refer to Figure 1 The preparation process of the energy-saving aluminum alloy cable in this embodiment includes the following steps: (1) A high-conductivity aluminum alloy rod was prepared by melting an aluminum ingot with a purity of 99.85wt%, and the alloy components were added: Si 0.03wt%, Fe 0.07wt%, B 0.03wt%, Cr, Mn, V and Ti 0.015wt%. The remaining impurity elements were controlled to 0.005wt%, and the balance was Al. After melting, 0.15wt% of refining agent was added for refining. After standing, the aluminum rod was prepared by continuous casting and rolling process. (2) drawing the aluminum rod obtained in step (1) into a single wire with a diameter of 2.8 mm; (3) 37 strands of the monofilaments prepared in step (2) are twisted into a conductor; (4) wrapping the conductor obtained in step (3) around a semi-conductive tape, and then simultaneously forming a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the surface of the semi-conductive tape through a three-layer co-extrusion process; (5) wrapping a soft copper tape around the surface of the insulating shielding layer obtained in step (4); (6) The polyvinyl chloride sheath material is coated on the surface of the soft copper strip obtained in step (5) through an extrusion process to form an outer protective layer.

[0031] The refining temperature is 755° C. and the standing time is 30 minutes.

[0032] The continuous casting and rolling process is controlled as follows: tundish temperature is 710°C, rolling temperature is 550°C, rolling temperature is 350°C, and rolling exit temperature is 300°C.

[0033] The conductor cross-section in step (3) is 230 mm² and the compression coefficient is 0.93.

[0034] In step (4), the thickness of the semi-conductive tape is 0.1 mm; and the overlapping wrapping rate is 15%.

[0035] In step (4), the conductor shielding layer has a thickness of 0.7 mm; the XLPE insulation layer has a thickness of 4.05 mm; the insulation shielding layer has a thickness of 0.7 mm; and after the three layers are co-extruded, the eccentricity of any cross section is ≤15%.

[0036] The thickness of the soft copper strip in step (5) is 0.1 mm; the overlap ratio between the copper strips is 10.

[0037] The thickness of the outer protective layer in step (6) is 1.68 mm. Example 3 Please refer to Figure 1 The preparation process of the energy-saving aluminum alloy cable in this embodiment includes the following steps: (1) A high-conductivity aluminum alloy rod was prepared by melting an aluminum ingot with a purity of 99.88wt%, and the alloy components were added: Si 0.03wt%, Fe 0.05wt%, B 0.03wt%, Cr, Mn, V and Ti 0.005wt%. The remaining impurity elements were controlled to 0.005wt%, and the balance was Al. After melting, 0.20wt% of refining agent was added for refining. After standing, the aluminum rod was prepared by continuous casting and rolling process. (2) drawing the aluminum rod obtained in step (1) into a monofilament with a diameter of 2.85 mm; (3) 37 strands of the monofilaments prepared in step (2) are twisted into a conductor; (4) wrapping the conductor obtained in step (3) around a semi-conductive tape, and then simultaneously forming a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the surface of the semi-conductive tape through a three-layer co-extrusion process; (5) wrapping a soft copper tape around the surface of the insulating shielding layer obtained in step (4); (6) The polyvinyl chloride sheath material is coated on the surface of the soft copper strip obtained in step (5) through an extrusion process to form an outer protective layer.

[0038] The refining temperature is 765° C. and the standing time is 50 min.

[0039] The continuous casting and rolling process is controlled as follows: tundish temperature is 720°C, rolling temperature is 560°C, rolling temperature is 380°C, and rolling exit temperature is 320°C.

[0040] The conductor cross-section in step (3) is 240 mm² and the compression coefficient is 0.92.

[0041] The thickness of the semi-conductive tape in step (4) is 0.12 mm; and the overlapping wrapping rate is 17%.

[0042] In step (4), the conductor shielding layer has a thickness of 0.8 mm; the XLPE insulation layer has a thickness of 4.28 mm; the insulation shielding layer has a thickness of 0.8 mm; and after the three layers are co-extruded, the eccentricity of any cross section is ≤15%.

[0043] The thickness of the soft copper strip in step (5) is 0.12 mm; the overlap rate between the copper strips is 15%.

[0044] The thickness of the outer protective layer in step (6) is 2 mm.

[0045] Comparative Example 1 On the basis of Example 3, B was not added, the Fe content was changed to 0.08%wt%, and the rest remained the same as Example 1.

[0046] Comparative Example 2 On the basis of Example 3, the refining temperature was changed to 740°C, the tundish temperature was changed to 690°C, the rolling temperature was changed to 420°C, and the rest was consistent with Example 3.

[0047] Comparative Example 3 On the basis of Example 3, the semi-conductive tape wrapping is omitted, and the rest remains the same as Example 3.

[0048] Comparative Example 4 On the basis of Example 3, step (2) is changed to drawing the aluminum rod into a single wire with a diameter of 2.96 mm; step (3) is changed to using 36 single wires to twist into a conductor, and the rest is consistent with Example 3.

[0049] Performance testing: Single-filament resistivity: tested according to GB / T 3048.2-2007 standard at 20°C; Cable DC resistance: According to IEC 60228:2004, the DC resistance of the cables of Example and Comparative Example with a length of 1 km was tested at 20°C. Tensile strength: The tensile strength of the examples and comparative examples was tested at a tensile rate of 5 mm / min according to GB / T 228.1-2010.

[0050] The test results show that the resistivity of the single wire obtained in the embodiment is less than 0.0275Ω·mm 2 / m, the cable DC resistance is less than 0.1178Ω / km, and the tensile strength is above 152MPa; from Comparative Example 1, it can be seen that the addition of element B (0.03-0.05wt%) reduces the resistivity; from Comparative Example 2, it can be seen that precise control of process temperature ensures mechanical properties; in Comparative Example 3, the omission of the semi-conductive tape leads to electric field distortion on the conductor surface and a local discharge of 23.4pC; in Comparative Example 4 (2.96mm, 36 pieces), only the single wire diameter is increased while the microstructure control is ignored, which leads to an increase in resistivity, and the reduction in cross-sectional area causes serious deterioration of resistance.

[0051] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for preparing an energy-saving aluminum alloy cable, characterized by: The following steps are involved: (1) A high-conductivity aluminum alloy rod is prepared by melting an aluminum ingot with a purity of ≥99.85wt%, adding the following alloy components: Si 0.025-0.035wt%, Fe 0.05-0.12wt%, B 0.03-0.05wt%, Cr, Mn, V and Ti ≤ 0.02wt%, and controlling the remaining impurity elements to ≤ 0.015wt%, with the balance being Al. After melting, 0.15-0.20wt% of a refining agent is added for refining, and after standing, the aluminum rod is prepared by continuous casting and rolling process; (2) drawing the aluminum rod obtained in step (1) into a monofilament; (3) twisting a plurality of monofilaments obtained in step (2) into a conductor; (4) wrapping the conductor obtained in step (3) around the semi-conductive tape, and then forming a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the surface of the semi-conductive tape from the inside to the outside in sequence through a three-layer co-extrusion process; (5) wrapping a soft copper tape around the surface of the insulating shielding layer obtained in step (4); (6) The polyvinyl chloride sheath material is coated on the surface of the soft copper strip obtained in step (5) through an extrusion process to form an outer protective layer.

2. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: The refining temperature is 755-765° C.; and the standing time is 30-50 minutes.

3. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: The continuous casting and rolling process is specifically as follows: tundish temperature 710-730°C, rolling entry temperature 550-570°C, rolling temperature 350-400°C, and exit temperature 300-350°C.

4. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: In step (2), the diameter of the monofilament is 2.8-2.9 mm, and the resistivity of the monofilament is ≤0.027586 Ω·mm² / m.

5. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: The conductor cross-section in step (3) is 230-250 mm², and the compression coefficient is ≥0.

90.

6. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: In step (4), the thickness of the semi-conductive tape is 0.1-0.15 mm; and the overlapping wrapping rate is 15% to 20%.

7. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: In step (4), the conductor shielding layer has a thickness of 0.7-0.9 mm; the XLPE insulation layer has a thickness of 4.05-4.6 mm; the insulation shielding layer has a thickness of 0.7-0.9 mm; and after the three layers are co-extruded, the eccentricity of any cross section is ≤15%.

8. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: The thickness of the soft copper strip in step (5) is 0.1-0.14 mm; and the overlap rate between the copper strips is 10-20%.

9. The process for preparing an energy-saving aluminum alloy cable according to claim 1, characterized in that: The thickness of the outer protective layer in step (6) is 1.68-2.2 mm.

10. A process for preparing the energy-saving aluminum alloy cable according to any one of claims 1 to 9, characterized in that: The DC resistance of the prepared cable at 20° C. is ≤0.1184Ω / km.

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