A 16 type circular compressed aluminum alloy wire and a method for manufacturing the same

Abstract

The application provides a 16 type circular compression high-conductivity high-strength aluminum alloy cable and a preparation method thereof. The conductor adopts an Al-Fe-Cu-Mg-Si-La multi-element micro-alloying system, and a full-process preparation process of two-stage step annealing, 6+10 layered pre-twisted concentric stranding, multi-pass staged circular compression, closed-loop tension constant-speed take-up. Through the synergistic effect of solid solution strengthening, grain refinement and grain boundary purification of multi-element alloy elements, the strength and conductivity of the aluminum alloy conductor are improved in both directions. At the same time, through the precise control of the full-process process, the conductor has high density, high roundness, high size consistency and excellent fatigue resistance. While effectively reducing the weight of the cable, the comprehensive mechanical properties, electrical properties and environmental tolerance performance are significantly improved, which is suitable for the complex service conditions of automobile low-voltage wires. It has the advantages of controllable preparation process, strong mass production adaptability and easy popularization and implementation.

Description

Technical Field

[0001] This application belongs to the field of cable manufacturing technology, specifically relating to a type 16 circular compressed aluminum alloy cable and its preparation method. Background Technology

[0002] In existing technologies, automotive low-voltage cables, as core components of the vehicle's electrical system, undertake crucial functions in power transmission and signal interaction. Their performance directly determines the safety, stability, and layout flexibility of the entire vehicle's electrical system. With the rapid development of the new energy and intelligent connected vehicle industry, the number of on-board electronic and electrical devices has increased significantly, and the space for wiring inside vehicles is becoming increasingly limited. The industry has placed stringent requirements on automotive wires for lightweighting, thin-walled construction, small specifications, and high reliability. Under the premise of meeting the same tensile strength and conductivity, the outer diameter, weight, and long-term service stability of cables have become core factors restricting the achievement of lightweight vehicle design and energy conservation and emission reduction goals.

[0003] In existing technologies, pure copper conductor automotive cables are the most widely used mainstream solution in the automotive wiring field due to their excellent conductivity and stable machinability. However, pure copper has a high density of 8.96 g / cm³. Under the condition of meeting the same current carrying capacity requirements, pure copper conductor automotive cables have inherent defects such as large outer diameter and excessive weight per meter. This not only occupies a large amount of limited laying space in the vehicle, making it unsuitable for the narrow space wiring layout requirements of intelligent vehicles, but also significantly increases the overall vehicle weight, directly affecting the driving range of new energy vehicles and the fuel economy of fuel vehicles, failing to meet the energy-saving and emission-reduction requirements of intelligent and lightweight automotive development. At the same time, copper resources are scarce and raw material prices fluctuate greatly, which is also not conducive to the long-term stable control of vehicle manufacturing costs. Conventional aluminum alloy conductor automotive cables, with their inherent lightweight advantage of aluminum (density only about 30% of copper), have become a major alternative to pure copper cables. Al-Fe binary aluminum alloy cables are currently the mainstream alternative in the industry, offering significant advantages in weight reduction and meeting the basic transmission requirements of automotive wiring. The 16-strand stranded structure commonly used in automotive wiring is also widely applied. However, these conventional aluminum alloy cables still have several insurmountable drawbacks: First, conventional Al-Fe binary aluminum alloy cables suffer from an inherent industry contradiction between strength and conductivity. Increasing the alloy element content to improve tensile strength leads to a significant decrease in conductivity, while maintaining conductivity fails to meet the mechanical performance requirements under stranding, compression, terminal crimping, and long-term bending conditions, easily resulting in wire breakage, deformation, and fatigue failure, making them unsuitable for the complex service conditions of automotive vibration and frequent bending. Second, for the 16-strand stranded structure, conventional aluminum alloy cables often use a simple concentric stranding + single-pass compression manufacturing process. The obtained Type 16 conductor has problems such as low roundness, large gap between single wires, easy misalignment between layers, poor dimensional consistency, and large outer diameter tolerance. It not only fails to meet the design requirements of thin-walled and small-size, but also leads to uneven insulation extrusion thickness and large fluctuations in conductor DC resistance, which directly affects the electrical performance stability and insulation protection reliability of the cable. Thirdly, the terminal crimping pull-out force of conventional aluminum alloy cables is insufficient, and the thermal aging, oil resistance, and high and low temperature cycle resistance are poor. When used for a long time in the harsh environment of high temperature and oil in the car engine compartment, problems such as poor contact and insulation cracking failure are likely to occur, posing serious electrical safety hazards to the whole vehicle.

[0004] Therefore, in order to comprehensively improve the lightweight level, mechanical properties, conductivity, dimensional consistency and reliability of automotive cables in complex environments, and to solve the industry pain points of existing pure copper cables, such as large weight, large laying space occupation, and failure to meet energy conservation and emission reduction requirements, as well as conventional 16-type aluminum alloy cables, such as unbalanced strong conductivity, poor processing adaptability and insufficient long-term service stability, it is now urgent to make targeted improvements to adapt to the development trend of intelligent and lightweight vehicles and improve the safety, stability and energy conservation and emission reduction effects of the whole vehicle electrical system. Summary of the Invention

[0005] This application aims to address the technical problems in the prior art, such as the large outer diameter and high weight per meter of pure copper conductor automotive cables, which occupy limited installation space in the vehicle and significantly increase the overall vehicle weight, failing to meet the energy-saving and emission-reduction requirements of intelligent and lightweight vehicles, and the large fluctuations in copper raw material prices and the difficulty in cost control; the industry bottleneck of the imbalance between strength and conductivity in conventional 16-type Al-Fe binary aluminum alloy cables, the poor conductor roundness and dimensional consistency of conductors produced by ordinary stranding and compression processes, insufficient terminal crimping pull-out force and environmental resistance, and the susceptibility to fatigue failure and electrical safety hazards. Therefore, this application proposes a 16-type circular compressed aluminum alloy cable and its preparation method.

[0006] This application adopts the following solution: a type 16 circular compressed aluminum alloy cable, including a wire core and a sheath layer covering the outer periphery of the wire core. The wire core includes an inner conductor group and an outer conductor group wound around the outer periphery of the inner conductor group. The material of the wire core is aluminum alloy A. The inner conductor group is formed by twisting six first conductor single wires together, and the outer conductor group is formed by twisting ten second conductor single wires together.

[0007] In some feasible embodiments, the aluminum alloy A, by mass percentage, consists of the following components: 0.60–0.90% iron, 0.15–0.30% copper, 0.05–0.15% magnesium, 0.03–0.08% silicon, 0.02–0.06% lanthanum, balance aluminum, and unavoidable impurities, with the content of a single impurity element ≤0.05 wt% and the total impurity content ≤0.15 wt%.

[0008] In some feasible embodiments, the aluminum alloy A, by mass percentage, comprises the following components: 0.70–0.80% iron, 0.20–0.28% copper, 0.06–0.12% magnesium, 0.04–0.06% silicon, 0.03–0.05% lanthanum, balance aluminum, and unavoidable impurities, wherein the content of a single impurity element is ≤0.05 wt%, and the total impurity content is ≤0.15 wt%.

[0009] In some feasible embodiments, the aluminum alloy A is composed of the following components by mass percentage: 0.77% iron, 0.22% copper, 0.10% magnesium, 0.05% silicon, 0.04% lanthanum, balance aluminum, and unavoidable impurities, with the content of a single impurity element ≤0.05wt% and the total impurity content ≤0.15wt%.

[0010] In some feasible embodiments, the method for preparing the aluminum alloy A includes the following steps:

[0011] Step 101. Add aluminum source, iron source, copper source, magnesium source, silicon source and lanthanum source to medium frequency melting furnace in sequence according to the preset alloy ratio, and melt at 730℃~760℃ under argon protective atmosphere for 30min~45min. After the melt obtained by melting is degassed by rotary degassing, slag removed from the furnace bottom, and Al-Ti-B grain refiner added online for grain refinement treatment, aluminum alloy rod billet with a diameter of 8.0mm is obtained by continuous casting and rolling process.

[0012] Step 102. The aluminum alloy rod blank obtained in step 101 is subjected to a multi-pass continuous drawing process, with a total drawing deformation of ≥99%, a drawing speed controlled at 12m / s~18m / s, and a deformation per pass controlled at 10%~15%, finally drawing an aluminum alloy monowire with a diameter of 0.2mm and a tolerance of ±0.003mm.

[0013] The aluminum alloy monofilament obtained in step 102 is placed in a pit-type annealing furnace. Under the protective atmosphere of argon, the temperature is first raised to 260°C at a rate of 80°C / h and held for 2 hours to eliminate the internal stress of processing. Then, the temperature is raised to 380°C at a rate of 50°C / h and held for 3 hours to adjust the grain size. Finally, the furnace is cooled to room temperature to obtain the finished aluminum alloy annealed monofilament.

[0014] In some feasible embodiments, the material of the sheath layer is selected from any one of polyvinyl chloride, polyethylene, cross-linked polyethylene, polyamide, ethylene propylene rubber, chloroprene rubber, silicone rubber, nitrile rubber, and polyurethane elastomer.

[0015] To address the technical problems raised in this application, this application also provides a method for preparing a type 16 circular compressed aluminum alloy cable, comprising the following steps:

[0016] Step 201. Using a 6+10 layered concentric stranding process, first take 6 aluminum alloy annealed finished monofilaments and strand them at a stranding speed of 2000 rpm and a stranding pitch of 14 mm to form the inner core wire; then take 10 aluminum alloy annealed finished monofilaments and strand them concentrically on the outside of the inner core wire at a stranding speed of 1500 rpm and a stranding pitch of 25 mm. During the stranding process, the pre-twist angle of the monofilaments is controlled at 3° to 5° to obtain a conductor blank with no gaps between layers and no warping of the monofilaments.

[0017] Step 202. Multi-pass graded circular compression: The conductor blank obtained in step 201 is sequentially compressed through a three-pass cemented carbide compression die. The die diameter of the first pass is 0.98 mm and the single-pass compression rate is 4.0%. The die diameter of the second pass is 0.95 mm and the single-pass compression rate is 5.95%. The die diameter of the third pass is 0.93 mm and the single-pass compression rate is 3.80%. The total compression rate is 13.14%. Neutral wire drawing lubricant is continuously injected into the die during the compression process to obtain a compressed conductor with a roundness of ≥98% and an outer diameter tolerance of ±0.02 mm.

[0018] Step 203. Connect the compressed conductor obtained in step 202 to the closed-loop tension control system. Control the take-up tension between 8N and 12N, set the wire pitch to 1.6mm, and synchronize the take-up speed with the stranding and compression speed to ensure that the conductor straightness deviation is ≤0.5mm / m. Finally, a type 16 circular compressed high-conductivity and high-strength aluminum alloy cable is obtained.

[0019] Compared with the prior art, this application has the following beneficial effects:

[0020] This application provides a type 16 circular compressed high-conductivity and high-strength aluminum alloy cable and its preparation method. The conductor adopts an Al-Fe-Cu-Mg-Si-La multi-element micro-alloying system, combined with a two-stage stepped annealing, 6+10 layered pre-twisted concentric stranding, multi-pass graded circular compression, and closed-loop tension constant speed winding process. Through the synergistic effect of solid solution strengthening, grain refinement, and grain boundary purification of multi-element alloying elements, the strength and conductivity of the aluminum alloy conductor are improved in both directions. At the same time, through precise control of the entire process, the conductor achieves high density, high roundness, high dimensional consistency, and excellent fatigue resistance. This solution effectively addresses the industry pain points of existing technologies, such as the large outer diameter and high weight of pure copper automotive wire conductors, which do not meet the requirements for lightweighting, energy conservation, and emission reduction, as well as the imbalance between strength and conductivity, short bending fatigue life, and poor processing adaptability of conventional Al-Fe binary aluminum alloy conductors. While achieving weight reduction, it significantly improves the comprehensive mechanical properties, electrical properties, and environmental resistance, and can adapt to the complex service conditions of automotive low-voltage wires. It has the advantages of controllable manufacturing process, strong mass production adaptability, and easy promotion and implementation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of a type 16 circular compressed aluminum alloy cable according to this application. Detailed Implementation

[0022] Combination Figure 1 Examples 1-3 and Comparative Examples 1-4 further illustrate the technical solutions proposed in this application.

[0023] Specifically, this application provides a type 16 circular compressed aluminum alloy cable, which includes a wire core 1 and a sheath layer 2 covering the outer periphery of the wire core 1. The wire core 1 includes an inner conductor group 10 and an outer conductor group 11 wound around the outer periphery of the inner conductor group 10. The wire core 1 is made of aluminum alloy A. The inner conductor group 10 is formed by twisting six first conductor single wires 100 together, and the outer conductor group 11 is formed by twisting ten second conductor single wires 110 together. Example 1

[0024] (1) The preparation method of aluminum alloy A includes the following steps:

[0025] Step 101. According to the composition table shown in Table 1, add aluminum source, iron source, copper source, magnesium source, silicon source and lanthanum source to the medium frequency melting furnace in sequence, and melt at 730℃ under argon protective atmosphere for 30 minutes. After the melt obtained by melting is degassed by rotary degassing, slag removed from the furnace bottom, and Al-Ti-B grain refiner added online for grain refinement treatment, aluminum alloy rod billet with a diameter of 8.0 mm is obtained by continuous casting and rolling process.

[0026] Step 102. The aluminum alloy rod blank obtained in Step 101 is subjected to a multi-pass continuous drawing process, with a total drawing deformation of ≥99%, a drawing speed controlled at 12m / s, and a deformation per pass controlled at 10%, and finally an aluminum alloy monofilament with a diameter of 0.2mm and a tolerance of ±0.003mm is obtained.

[0027] The aluminum alloy monofilament obtained in step 102 is placed in a pit-type annealing furnace. Under the protective atmosphere of argon, the temperature is first raised to 260°C at a rate of 80°C / h and held for 2 hours to eliminate the internal stress of processing. Then, the temperature is raised to 380°C at a rate of 50°C / h and held for 3 hours to adjust the grain size. Finally, the furnace is cooled to room temperature to obtain the finished aluminum alloy annealed monofilament.

[0028] (2) A method for preparing a type 16 circular compressed aluminum alloy cable, comprising the following steps:

[0029] Step 201. Using a 6+10 layered concentric stranding process, first take 6 aluminum alloy annealed finished monofilaments and strand them at a stranding speed of 2000 rpm and a stranding pitch of 14 mm to form the inner core wire; then take 10 aluminum alloy annealed finished monofilaments and strand them concentrically on the outside of the inner core wire at a stranding speed of 1500 rpm and a stranding pitch of 25 mm. During the stranding process, the pre-twist angle of the monofilaments is controlled at 3° to obtain a conductor blank with no gaps between layers and no warping of the monofilaments.

[0030] Step 202. Multi-pass graded circular compression: The conductor blank obtained in step 201 is sequentially compressed through a three-pass cemented carbide compression die. The die diameter of the first pass is 0.98 mm and the single-pass compression rate is 4.0%. The die diameter of the second pass is 0.95 mm and the single-pass compression rate is 5.95%. The die diameter of the third pass is 0.93 mm and the single-pass compression rate is 3.80%. The total compression rate is 13.14%. Neutral wire drawing lubricant is continuously injected into the die during the compression process to obtain a compressed conductor with a roundness of ≥98% and an outer diameter tolerance of ±0.02 mm.

[0031] Step 203. Connect the compressed conductor obtained in step 202 to the closed-loop tension control system. Control the take-up tension at 8N, set the wire pitch to 1.6mm, and synchronize the take-up speed with the stranding compression speed to ensure that the conductor straightness deviation is ≤0.5mm / m. Finally, a type 16 circular compressed high conductivity high strength aluminum alloy cable is obtained. Example 2

[0032] (1) The preparation method of aluminum alloy A includes the following steps:

[0033] Step 101. According to the composition table shown in Table 1, aluminum source, iron source, copper source, magnesium source, silicon source and lanthanum source are added to the medium frequency melting furnace in sequence and melted at 740℃ under argon protective atmosphere for 40 minutes. The melt obtained is subjected to rotary degassing, furnace bottom slag removal and online addition of Al-Ti-B grain refiner for grain refinement treatment. Then, aluminum alloy rod billets with a diameter of 8.0 mm are obtained by continuous casting and rolling process.

[0034] Step 102. The aluminum alloy rod blank obtained in step 101 is subjected to a multi-pass continuous drawing process, with a total drawing deformation of ≥99%, a drawing speed controlled at 15m / s, and a deformation per pass controlled at 12%, and finally an aluminum alloy monofilament with a diameter of 0.2mm and a tolerance of ±0.003mm is obtained.

[0035] The aluminum alloy monofilament obtained in step 102 is placed in a pit-type annealing furnace. Under the protective atmosphere of argon, the temperature is first raised to 260°C at a rate of 80°C / h and held for 2 hours to eliminate the internal stress of processing. Then, the temperature is raised to 380°C at a rate of 50°C / h and held for 3 hours to adjust the grain size. Finally, the furnace is cooled to room temperature to obtain the finished aluminum alloy annealed monofilament.

[0036] (2) A method for preparing a type 16 circular compressed aluminum alloy cable, comprising the following steps:

[0037] Step 201. Using a 6+10 layered concentric stranding process, first take 6 aluminum alloy annealed finished monofilaments and strand them at a stranding speed of 2000 rpm and a stranding pitch of 14 mm to form the inner core wire; then take 10 aluminum alloy annealed finished monofilaments and strand them concentrically on the outside of the inner core wire at a stranding speed of 1500 rpm and a stranding pitch of 25 mm. During the stranding process, the pre-twist angle of the monofilaments is controlled at 4° to obtain a conductor blank with no gaps between layers and no warping of the monofilaments.

[0038] Step 202. Multi-pass graded circular compression: The conductor blank obtained in step 201 is sequentially compressed through a three-pass cemented carbide compression die. The die diameter of the first pass is 0.98 mm and the single-pass compression rate is 4.0%. The die diameter of the second pass is 0.95 mm and the single-pass compression rate is 5.95%. The die diameter of the third pass is 0.93 mm and the single-pass compression rate is 3.80%. The total compression rate is 13.14%. Neutral wire drawing lubricant is continuously injected into the die during the compression process to obtain a compressed conductor with a roundness of ≥98% and an outer diameter tolerance of ±0.02 mm.

[0039] Step 203. Connect the compressed conductor obtained in step 202 to the closed-loop tension control system. Control the take-up tension at 10N, set the wire pitch to 1.6mm, and synchronize the take-up speed with the stranding compression speed to ensure that the conductor straightness deviation is ≤0.5mm / m. Finally, a type 16 circular compressed high conductivity high strength aluminum alloy cable is obtained. Example 3

[0040] (1) The preparation method of aluminum alloy A includes the following steps:

[0041] Step 101. According to the composition table shown in Table 1, aluminum source, iron source, copper source, magnesium source, silicon source and lanthanum source are added to the medium frequency melting furnace in sequence and melted at 760℃ under argon protective atmosphere for 45 minutes. The melt obtained is subjected to rotary degassing, furnace bottom slag removal and online addition of Al-Ti-B grain refiner for grain refinement treatment. Then, aluminum alloy rod billets with a diameter of 8.0 mm are obtained by continuous casting and rolling process.

[0042] Step 102. The aluminum alloy rod blank obtained in step 101 is subjected to a multi-pass continuous drawing process, with a total drawing deformation of ≥99%, a drawing speed controlled at 18m / s, and a deformation per pass controlled at 15%, and finally an aluminum alloy monofilament with a diameter of 0.2mm and a tolerance of ±0.003mm is obtained.

[0043] The aluminum alloy monofilament obtained in step 102 is placed in a pit-type annealing furnace. Under the protective atmosphere of argon, the temperature is first raised to 260°C at a rate of 80°C / h and held for 2 hours to eliminate the internal stress of processing. Then, the temperature is raised to 380°C at a rate of 50°C / h and held for 3 hours to adjust the grain size. Finally, the furnace is cooled to room temperature to obtain the finished aluminum alloy annealed monofilament.

[0044] (2) A method for preparing a type 16 circular compressed aluminum alloy cable, comprising the following steps:

[0045] Step 201. Using a 6+10 layered concentric stranding process, first take 6 aluminum alloy annealed finished monofilaments and strand them at a stranding speed of 2000 rpm and a stranding pitch of 14 mm to form the inner core wire; then take 10 aluminum alloy annealed finished monofilaments and strand them concentrically on the outside of the inner core wire at a stranding speed of 1500 rpm and a stranding pitch of 25 mm. During the stranding process, the pre-twist angle of the monofilaments is controlled at 5° to obtain a conductor blank with no gaps between layers and no warping of the monofilaments.

[0046] Step 202. Multi-pass graded circular compression: The conductor blank obtained in step 201 is sequentially compressed through a three-pass cemented carbide compression die. The die diameter of the first pass is 0.98 mm and the single-pass compression rate is 4.0%. The die diameter of the second pass is 0.95 mm and the single-pass compression rate is 5.95%. The die diameter of the third pass is 0.93 mm and the single-pass compression rate is 3.80%. The total compression rate is 13.14%. Neutral wire drawing lubricant is continuously injected into the die during the compression process to obtain a compressed conductor with a roundness of ≥98% and an outer diameter tolerance of ±0.02 mm.

[0047] Step 203. Connect the compressed conductor obtained in step 202 to the closed-loop tension control system. Control the take-up tension at 12N, set the wire pitch to 1.6mm, and synchronize the take-up speed with the stranding compression speed to ensure that the conductor straightness deviation is ≤0.5mm / m. Finally, a type 16 circular compressed high-conductivity high-strength aluminum alloy cable is obtained.

[0048] Comparative Example 1

[0049] The alloy composition system of aluminum alloy A was modified so that only iron and aluminum elements were retained, while the other components and all process parameters remained completely unchanged. The specific elemental composition of aluminum alloy in Comparative Example 1 is shown in Table 1.

[0050] Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 1 is that a pure copper system is used instead of aluminum alloy A, while the processes of the other components remain unchanged. The specific elemental composition of the pure copper system in Comparative Example 2 is shown in Table 1.

[0052] Comparative Example 3

[0053] The difference between Comparative Example 3 and Example 1 is that the alloy composition system and all process parameters are completely consistent with Example 1. The only difference is that the 6+10 layered pre-twisted concentric stranding process is replaced with the industry-standard 16-wire one-time concentric stranding process. The specific process is as follows: 16 aluminum alloy annealed finished wires are simultaneously fed into the stranding machine and the whole concentric stranding is completed in one go. The stranding speed is uniformly set to 1800 rpm and the stranding pitch is uniformly set to 22 mm. No wire pre-twisting is set during the stranding process, and all other parameters remain unchanged.

[0054] Comparative Example 4

[0055] The difference between Comparative Example 4 and Example 1 is that the alloy composition system and all process parameters are completely consistent with Example 1. The only difference is that the three-pass graded circular compression process is replaced with a single-pass one-time compression process. Specifically, only one cemented carbide compression mold with a bore diameter of 0.93 mm is used to complete the compression molding with a total compression ratio of 13.14% in one pass. The lubricant parameters and compression speed during the compression process are completely consistent with Example 1, and all other parameters remain unchanged.

[0056] Table 1. Conductor alloy composition table for Examples 1-3

[0057]

[0058] The conductor monofilaments prepared from the corresponding conductor alloys in Examples 1-3 and Comparative Examples 1-4 were prepared in steps 101-103 and tested according to the test standards in Table 2 below. The test results are shown in Table 2 below.

[0059] Table 2 Test Results of Conductor Monofilament Finished Products

[0060]

[0061] The circular compressed conductor products prepared from the corresponding conductor alloys in Examples 1-3 and Comparative Examples 1-4 were prepared in steps 201-202 and tested according to the test standards in Table 3 below. The test results are shown in Table 3 below.

[0062] Table 3 Test Results of Circular Compressed Conductors

[0063]

[0064]

[0065] Continued from Table 3

[0066]

[0067]

[0068] The corresponding automotive low-voltage cables prepared from the corresponding conductor alloys in Examples 1-3 and Comparative Examples 1-4 were tested according to the test standards listed in Table 4. Note: All cable samples uniformly adopted XLPE insulation with a temperature resistance of 105℃, nominal insulation thickness of 0.4mm, and rated voltage of 60V DC, conforming to GB / T 25085-2010 "Road Vehicle Low-Voltage Cables" standard. The test results are shown in Table 4 below.

[0069] Table 4 Test Results of Finished Automotive Low-Voltage Cables

[0070]

[0071] Table 4 (continued)

[0072]

[0073]

[0074] As shown in Tables 1-4, in Examples 1-3, the Al-Fe-Cu-Mg-Si-La multi-element microalloying system is used as the core matrix material for the 16 / circular compressed aluminum alloy conductor. Combined with a precise full-process preparation process including two-stage stepped annealing, 6+10 layered pre-twisted concentric stranding, multi-pass graded circular compression, and closed-loop tension constant speed winding, a synergistic modification effect of solid solution strengthening, grain refinement, and grain boundary purification can be introduced into the aluminum alloy matrix. At the same time, the high density, high roundness, and low stress uniform distribution of the conductor structure are achieved through full-process process control. From the two dimensions of material source and preparation process, the inherent contradictions in the industry, such as the trade-off between strength and conductivity of Al-Fe aluminum alloys used in automotive wiring harnesses, poor dimensional consistency after stranding and compression, and insufficient bending fatigue life, are broken.

[0075] Specifically, in the multi-element microalloying system, Fe, as the core strengthening element, can form a dispersed Al-Fe intermetallic compound with Al, improving the tensile strength and thermal stability of the alloy matrix; Cu and Mg, as solid solution strengthening elements, can dissolve in the Al matrix to form lattice distortion, hindering dislocation movement and further improving the alloy strength, while also forming a synergistic effect with other elements to avoid excessive loss of conductivity; Si can refine the as-cast grains of the alloy, reduce ingot defects, and improve the drawing and forming performance of the alloy; La, a rare earth element, can purify the alloy grain boundaries, eliminate impurities and brittle phases at the grain boundaries, reduce lattice distortion, and simultaneously optimize conductivity while improving the alloy strength. Examples 1-3, through gradient design of component content, specifically within the ranges of 0.60%-0.90%Fe, 0.15%-0.30%Cu, 0.05%-0.15%Mg, 0.03%-0.08%Si, and 0.02%-0.06%La, all achieved a bidirectional improvement in strength and conductivity. In the corresponding test data, the tensile strength of the single filament in Examples 1-3 all reached above 152MPa, and the conductivity all reached above 60.40%, far exceeding the binary aluminum alloy system of Comparative Example 1.

[0076] More specifically, in the manufacturing process, the two-stage stepped annealing process can eliminate the internal stress of the single filament after drawing and control the grain size step by step, improving plasticity while ensuring the strength of the single filament, and providing excellent processing performance for subsequent stranding and compression; the layered pre-twisted concentric stranding process, through the design of differentiated stranding speed and stranding pitch of the inner and outer layers, combined with the control of the single filament pre-twisting angle of 3°-5°, can achieve tight stranding of 16 single filaments in a 6+10 structure, eliminating interlayer gaps and single filament warping. In the corresponding test data, the interfilament gap rate of Examples 1-3 is controlled within 0.90%, which is far lower than the conventional stranding process of Comparative Example 3; the multi-pass graded circular compression process, through the mold design of 3-pass gradient compression rate, can gradually achieve the densification compression of the conductor, avoiding single-pass compression. The problems of conductor springback, single-wire breakage, and insufficient roundness caused by compression are addressed. In the test data of Examples 1-3, the conductor roundness all reached over 98.00%, which is far higher than the single-pass compression process of Comparative Example 4. With the constant tension winding of the closed-loop tension control system, the straightness and dimensional consistency of the conductor can be guaranteed, and the high-precision control of the conductor outer diameter tolerance ≤ ±0.02mm can be achieved. At the same time, the bending fatigue life and subsequent processing adaptability of the conductor are greatly improved. In the test data of Examples 1-3, the bending fatigue life all reached over 2450 cycles, which far exceeded the conventional process system of Comparative Examples 1, 3, and 4, and was also better than the 2200 cycles of pure copper Comparative Example 2. The overall application performance of the cable, such as wear resistance, thermal aging performance, and terminal crimping pull-out force, is significantly improved.

[0077] In Comparative Example 1, Cu, Mg, Si, and La alloying modifiers were removed, and only the Al-Fe binary alloy system was retained. The remaining components and processes remained completely unchanged from Example 1. On the one hand, the absence of Cu and Mg solid solution strengthening elements in the binary alloy system prevents the use of lattice distortion to hinder dislocation movement and thus improve the tensile strength of the alloy matrix. Furthermore, the lack of Si grain refiners and La rare-earth grain boundary purifying elements prevents the refinement of as-cast grains and the elimination of grain boundary impurities and brittle phases. Consequently, the strength and conductivity of the alloy matrix cannot be synergistically improved. Correspondingly, the room temperature tensile strength of the monofilament decreased from 168 MPa in Example 1 to 125 MPa, the conductivity decreased from 61.50% to 59.30%, and the DC resistivity at 20°C increased from 28.1 nΩ·m to 29.5 nΩ·m. On the other hand, the plasticity and fatigue resistance of the binary alloy system decrease. Uneven stress distribution within the conductor after stranding and compression leads to stress concentration during bending, causing the bending fatigue life to plummet from 2600 cycles in Example 1 to 1450 cycles. Ultimately, the overall application performance of the cable, including wear resistance and terminal crimping pull-out force, significantly declines.

[0078] In Comparative Example 2, a pure copper T2 system was used to replace the Al-Fe-Cu-Mg-Si-La multi-element aluminum alloy system of this patent, while the remaining processes remained completely unchanged from Example 1. On the one hand, the density of pure copper is much greater than that of aluminum alloy, causing the conductor weight per meter to increase significantly from 1.48 g / m in Example 1 to 4.45 g / m. This fails to achieve the core design goals of lightweighting and energy conservation in automotive wiring harnesses, and completely fails to address the technical defects of the background technology where the conductor weight of pure copper automotive wiring harnesses is too heavy and does not meet the requirements for lightweighting. On the other hand, although pure copper conductors have higher conductivity, under the same process conditions, their long-term bending fatigue performance cannot match that of the optimized aluminum alloy system of this patent. At the same time, the cost of pure copper raw materials is much higher than that of aluminum alloys, making it unsuitable for the cost control requirements of large-scale mass production of automotive wiring harnesses.

[0079] In Comparative Example 3, the alloy composition system was completely identical to that of Example 1, except that the layered pre-twisted concentric stranding process was replaced with the industry-standard one-time concentric stranding process, while the other components and processes remained unchanged. On the one hand, the conventional concentric stranding process did not set the pre-twisting angle of the single filaments and the layered differentiated stranding parameters. After stranding, the interlayer gaps were large and prone to warping. In the corresponding test data, the inter-filament gap ratio increased from 0.80% in Example 1 to 4.20%, the conductor roundness decreased from 98.50% to 93.00%, and the outer diameter tolerance increased from ±0.015mm to ±0.050mm. On the other hand, the internal stress distribution of the conductor was uneven after stranding, and stress concentration was prone to occur during bending, resulting in a decrease in bending fatigue life from 2600 cycles in Example 1 to 1800 cycles. At the same time, the poor conductor size consistency led to uneven insulation extrusion thickness. Ultimately, the overall performance of the cable, such as insulation resistance, wear resistance, and terminal crimping pull-out force, all showed significant deterioration.

[0080] In Comparative Example 4, the alloy composition system and stranding process were completely identical to those in Example 1, except that the three-pass graded circular compression process was replaced with a single-pass one-time compression process, while the other components and processes remained unchanged. On the one hand, single-pass high compression molding easily leads to conductor springback, single-wire misalignment, and loose internal structure. Correspondingly, the inter-wire gap ratio in the test data increased from 0.80% in Example 1 to 3.80%, the conductor roundness decreased from 98.50% to 94.00%, and the outer diameter tolerance increased from ±0.015mm to ±0.045mm. On the other hand, single-pass compression leads to excessive residual stress inside the conductor, which easily causes wire breakage failure during bending. The bending fatigue life decreased from 2600 cycles in Example 1 to 1750 cycles. Ultimately, the dimensional stability and long-term service reliability of the cable both decreased significantly.

[0081] This application provides a type 16 circular compressed high-conductivity and high-strength aluminum alloy cable and its preparation method. The conductor adopts an Al-Fe-Cu-Mg-Si-La multi-element micro-alloying system, combined with a two-stage stepped annealing, 6+10 layered pre-twisted concentric stranding, multi-pass graded circular compression, and closed-loop tension constant speed winding process. Through the synergistic effect of solid solution strengthening, grain refinement, and grain boundary purification of multi-element alloying elements, the strength and conductivity of the aluminum alloy conductor are improved in both directions. At the same time, through precise control of the entire process, the conductor achieves high density, high roundness, high dimensional consistency, and excellent fatigue resistance. This solution effectively addresses the industry pain points of existing technologies, such as the large outer diameter and high weight per meter of pure copper automotive wire conductors, which do not meet the requirements for lightweighting, energy conservation, and emission reduction, as well as the imbalance between strength and conductivity, short bending fatigue life, and poor processing adaptability of conventional Al-Fe binary aluminum alloy conductors. While achieving weight reduction, it significantly improves the comprehensive mechanical properties, electrical properties, and environmental resistance, making it fully adaptable to the complex service conditions of automotive low-voltage wires. It has the advantages of controllable manufacturing process, strong mass production adaptability, and ease of promotion and implementation.

[0082] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A type 16 circular compressed aluminum alloy cable, characterized in that, It includes a wire core (1) and a sheath layer (2) covering the outer periphery of the wire core (1). The wire core (1) includes an inner conductor group (10) and an outer conductor group (11) wound around the outer periphery of the inner conductor group (10). The wire core (1) is made of aluminum alloy A. The inner conductor group (10) is formed by twisting six first conductor monofilaments (100) together. The outer conductor group (11) is formed by twisting ten second conductor monofilaments (110) together.

2. The 16-type circular compressed aluminum alloy cable according to claim 1, characterized in that, The aluminum alloy A, by mass percentage, is composed of the following components: iron 0.60-0.90, copper 0.15-0.30, magnesium 0.05-0.15, silicon 0.03-0.08, lanthanum 0.02-0.06, balance aluminum, and unavoidable impurities, with the content of a single impurity element ≤0.05wt% and the total impurity content ≤0.15wt%.

3. The 16-type circular compressed aluminum alloy cable according to claim 1, characterized in that, The aluminum alloy A, by mass percentage, is composed of the following components: iron 0.70-0.80, copper 0.20-0.28, magnesium 0.06-0.12, silicon 0.04-0.06, lanthanum 0.03-0.05, balance aluminum, and unavoidable impurities, with the content of a single impurity element ≤0.05wt% and the total impurity content ≤0.15wt%.

4. A type 16 circular compressed aluminum alloy cable according to claim 1, characterized in that, The aluminum alloy A, by mass percentage, is composed of the following components: 0.77% iron, 0.22% copper, 0.10% magnesium, 0.05% silicon, 0.04% lanthanum, balance aluminum, and unavoidable impurities, with the content of a single impurity element ≤0.05wt% and the total impurity content ≤0.15wt%.

5. A type 16 circular compressed aluminum alloy cable according to claim 1, characterized in that, The preparation method of the aluminum alloy A includes the following steps: Step 101. Add aluminum source, iron source, copper source, magnesium source, silicon source and lanthanum source to medium frequency melting furnace in sequence according to the preset alloy ratio, and melt at 730℃~760℃ under argon protective atmosphere for 30min~45min. After the melt obtained by melting is degassed by rotary degassing, slag removed from the furnace bottom, and Al-Ti-B grain refiner added online for grain refinement treatment, aluminum alloy rod billet with a diameter of 8.0mm is obtained by continuous casting and rolling process. Step 102. The aluminum alloy rod blank obtained in step 101 is subjected to a multi-pass continuous drawing process, with a total drawing deformation of ≥99%, a drawing speed controlled at 12m / s~18m / s, and a deformation per pass controlled at 10%~15%, finally drawing an aluminum alloy monowire with a diameter of 0.2mm and a tolerance of ±0.003mm. The aluminum alloy monofilament obtained in step 102 is placed in a pit-type annealing furnace. Under the protective atmosphere of argon, the temperature is first raised to 260°C at a rate of 80°C / h and held for 2 hours to eliminate the internal stress of processing. Then, the temperature is raised to 380°C at a rate of 50°C / h and held for 3 hours to adjust the grain size. Finally, the furnace is cooled to room temperature to obtain the finished aluminum alloy annealed monofilament.

6. A type 16 circular compressed aluminum alloy cable according to claim 1, characterized in that, The material of the sheath layer (2) is selected from any one of polyvinyl chloride, polyethylene, cross-linked polyethylene, polyamide, ethylene propylene rubber, chloroprene rubber, silicone rubber, nitrile rubber, and polyurethane elastomer.

7. A method for preparing a type 16 circular compressed aluminum alloy cable according to any one of claims 1-6, characterized in that, Includes the following steps: Step 201. Using a 6+10 layered concentric stranding process, first take 6 aluminum alloy annealed finished monofilaments and strand them at a stranding speed of 2000 rpm and a stranding pitch of 14 mm to form the inner core wire; then take 10 aluminum alloy annealed finished monofilaments and strand them concentrically on the outside of the inner core wire at a stranding speed of 1500 rpm and a stranding pitch of 25 mm to obtain a conductor blank with no gaps between layers and no warping of the monofilaments; Step 202. Multi-pass graded circular compression: The conductor blank obtained in step 201 is sequentially compressed through a three-pass cemented carbide compression die. The first pass has a die aperture of 0.98 mm and a single-pass compression rate of 4.0%; the second pass has a die aperture of 0.95 mm and a single-pass compression rate of 5.95%; and the third pass has a die aperture of 0.93 mm and a single-pass compression rate of 3.80%, with a total compression rate of 13.14%. During the compression process, neutral wire drawing lubricant is continuously injected into the die to obtain a compressed conductor. Step 203. Connect the compressed conductor obtained in step 202 to the servo closed-loop tension control system. Control the take-up tension between 8N and 12N, and set the wire pitch to 1.6mm. Use a synchronous encoder to achieve synchronous matching between the take-up speed and the stranding compression speed to ensure that the conductor straightness deviation is ≤0.5mm / m.

8. The method for preparing a type 16 circular compressed aluminum alloy cable according to claim 7, characterized in that, In step 201, the pre-twist angle of the monofilament is controlled between 3° and 5° during the twisting process.

9. The method for preparing a type 16 circular compressed aluminum alloy cable according to claim 7, characterized in that, In step 202, the roundness of the compressed conductor is ≥98% and the outer diameter tolerance is ±0.02mm.

10. The method for preparing a type 16 circular compressed aluminum alloy cable according to claim 7, characterized in that, In step 203, the winding tension is controlled between 8N and 12N.

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