Preparation method of aluminum alloy low-voltage cable for bending-resistant unmanned aerial vehicle charging pile

Abstract

This invention discloses a method for preparing a bend-resistant aluminum alloy low-voltage cable for drone charging stations, comprising the following steps: S1, preparing composite conductor monofilaments; S2, preparing insulation layer masterbatch; S3, preparing sheath layer masterbatch; S4, cable composite and final molding. This invention prepares the core conductor using precision metallurgical processes, employing a high-toughness aluminum-magnesium-silicon-copper alloy as the inner core and a high-conductivity aluminum-magnesium-silicon-scandium-zirconium alloy as the outer conductor layer, with nano-alumina dispersion reinforcing the interface between the two. The three layers are metallurgically bonded through hot isostatic pressing, and through temperature-controlled drawing and multi-stage aging treatment, a composite conductor monofilament with high toughness, high conductivity, and fatigue resistance is obtained. This solves the problem of micro-cracks and increased resistance caused by repeated bending of the conductor, giving the cable excellent bending life and stable electrical and mechanical properties, making it suitable for the high-frequency bending scenarios of drone automatic charging.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, specifically to a method for manufacturing a bend-resistant aluminum alloy low-voltage cable for drone charging stations. Background Technology

[0002] Bending-resistant aluminum alloy low-voltage cables for drone charging stations are primarily used in mobile charging scenarios such as automated drone charging stations. These scenarios require cables to maintain stable electrical performance and mechanical reliability during frequent plugging, unplugging, and bending. Aluminum alloy cables, with their lightweight, low cost, and excellent conductivity, are an ideal replacement for traditional copper cables, especially suitable for drone charging infrastructure that requires reduced overall weight and lower deployment costs.

[0003] In existing technologies, aluminum alloy cables typically use AA8030 series aluminum alloy materials as conductors, and their mechanical properties are improved through special compaction processes and annealing treatments. For charging pile applications, various improved designs have emerged, such as wrapping the conductor with semi-conductive nylon tape to improve heat dissipation efficiency, or using composite materials such as chlorinated polyethylene and epoxy resin to construct the outer sheath to enhance waterproofing and mechanical properties. Furthermore, some technologies aim to improve the cable's toughness and flexural strength by adding rare earth elements, iron, boron, etc., to the aluminum matrix and subjecting it to high-temperature heat treatment.

[0004] However, existing aluminum alloy cable technology still struggles to completely resolve reliability issues in applications like drone charging stations that require extremely high frequency and small-radius bending. When cables are repeatedly bent, the conductor is prone to micro-cracks or even breakage due to fatigue stress. Simultaneously, the adhesion between the insulation layer and the conductor may be insufficient, leading to insulation bulging or peeling at the bends. This structural damage caused by frequent bending significantly increases contact resistance, triggers localized overheating, and ultimately affects charging safety and cable lifespan, posing a significant challenge to current technology. Summary of the Invention

[0005] The existing technology has the following problems: existing cables cannot solve the problem of insufficient operational reliability caused by conductor fatigue fracture and insulation stripping failure in high-frequency and small-radius bending scenarios of drone charging piles. In order to address the above technical problems, the present invention provides a method for preparing a bending-resistant aluminum alloy low-voltage cable for drone charging piles.

[0006] The technical solution of this invention is: a method for preparing a bend-resistant aluminum alloy low-voltage cable for drone charging stations, comprising the following steps: S1. Preparation of composite structure conductor single wire: S1-1. By mass percentage, 0.8-1.5% magnesium, 0.2-0.6% copper, 0.1-0.3% silicon, and the balance aluminum are melted and cast into round bars to obtain an alloy inner core; 0.4-0.9% magnesium, 0.08-0.15% scandium, 0.10-0.20% zirconium, and the balance aluminum are melted and cast to obtain a tube blank; S1-2. Disperse γ-alumina powder with an average particle size of 50-100nm in a binder solution to form a slurry, coat it on the outer surface of the alloy core, dry it and assemble it into the tube blank, and hot isostatically press it at 480-520℃ and 100-150MPa argon atmosphere for 1-2 hours to form a composite ingot. S1-3. The composite ingot is first subjected to 3-5 passes of hot drawing, followed by 4-10 passes of cold drawing. Each pass is annealed in a hydrogen-containing protective atmosphere at 300-350℃. Finally, it is drawn to a conductor wire diameter of 0.8-1.5 mm. Then, it undergoes two-stage aging treatment to obtain a composite structure conductor wire. The hydrogen-containing atmosphere is an argon-hydrogen mixed atmosphere with hydrogen accounting for 5-10% of the volume and the balance being argon. S2. Preparation of insulating layer masterbatch: Polyolefin elastomer, maleic anhydride-grafted polyolefin, hydrogenated styrene elastomer, surface-modified nano silica and antioxidant are melt-blended; the blend is melt-conveyed through a twin-screw extruder at 155-170℃, and 0.5-1.0% of peroxide crosslinking agent by weight of the material is injected into the rear section of the barrel. The in-situ dynamic crosslinking reaction is completed by the shearing and mixing action generated by the screw combination, and the insulating layer masterbatch is obtained by underwater pelletizing. S3. Preparation of sheath layer masterbatch: Thermoplastic polyurethane, polyether ester elastomer, chopped PBO fiber, carbon nanotube and ultraviolet light stabilizer are melt-blended and granulated to obtain inner sheath masterbatch; chlorinated polyethylene, nitrile rubber, aluminum hydroxide, chopped aramid fiber and silicone masterbatch are melt-blended and granulated to obtain outer sheath masterbatch. S4. Cable Composite and Final Molding: After stranding 7-19 composite conductor filaments into a cable core, insulation masterbatch is extruded over the cable core to obtain an insulated core. Then, an adhesive layer is coated on the surface of the insulated core, and the inner and outer sheaths are simultaneously wrapped through a coaxial double-layer co-extrusion rotary die to form a gradient outer sheath. Finally, after cooling and winding, an aluminum alloy low-voltage cable is obtained.

[0007] Explanation: This method innovatively applies hot isostatic pressing composite, nano-interface strengthening, and multi-stage aging treatment processes derived from high-performance structural materials to cable conductor manufacturing, resolving the inherent contradiction of balancing toughness and conductivity in aluminum alloy conductors. Then, it combines the in-situ dynamic cross-linking process of the insulation layer with the rotary die fiber-oriented co-extrusion process of the outer sheath, simultaneously overcoming the fatigue resistance problem of polymer sheaths under repeated bending from both material modification and structural design perspectives. This forms a completely new technical path for the preparation of specialized cables, producing a significant synergistic effect and achieving improved bending resistance.

[0008] Further, the adhesive solution in S1-2 is an ethanol solution containing 3-5% polyvinyl butyral by mass, the slurry has a solid content of 10-20% by mass, and the coating thickness is 100-200μm; in the two-stage aging treatment in S1-3: the temperature of the first stage is 100-120℃, and the holding time is 10-15 h; the temperature of the second stage is 150-170℃, and the holding time is 5-10 h.

[0009] Explanation: By setting the PVB concentration in the binder solution to 3-5%, the solid content of the slurry to 10-20%, and the coating thickness to 100-200μm, a suitable thickness, uniformly dispersed nanoparticles, and firmly bonded interfacial reinforcement layer can be constructed between the alloy core and the outer conductor layer. This effectively transfers stress, inhibits crack propagation, and maintains good electrical continuity. A two-stage aging process of 100-120℃ / 10-15h followed by 150-170℃ / 5-10h guides the stepwise and uniform precipitation of the reinforcing phase in the alloy, enabling the composite conductor to achieve high strength while maintaining excellent toughness and fatigue resistance, thus meeting the extreme requirements of frequent bending on the comprehensive mechanical properties of the conductor material.

[0010] Further, by weight, the raw material ratio of the insulating layer masterbatch in S2 is: 100 parts of polyolefin elastomer, 20-30 parts of maleic anhydride-grafted polyolefin, 5-10 parts of hydrogenated styrene elastomer, 8-15 parts of surface-modified nano silica, and 0.3-0.8 parts of antioxidant.

[0011] Description: Using 100 parts of polyolefin elastomer (POE) as the matrix, 20-30 parts of maleic anhydride-grafted polyolefin (POE-g-MAH) as a compatibilizer, 5-10 parts of hydrogenated styrene-based elastomer (SEBS) for further toughening, and 8-15 parts of surface-modified nano-silica for reinforcement, the maleic anhydride-grafted polyolefin significantly improves the interfacial compatibility between the nanofiller and the matrix, as well as between the SEBS phase and the POE phase, synergistically enhancing the toughness of the blend. The addition of modified nano-silica, while improving strength, modulus, and heat resistance, does not excessively impair the material's flexibility due to its good dispersibility, providing an ideal matrix for subsequent in-situ dynamic crosslinking.

[0012] Further, the preparation method of the surface-modified nano-silica in S2 is as follows: by weight, 1-3 parts of silane coupling agent KH-570 and 0.5-1.5 parts of titanate coupling agent NDZ-201 are dissolved together in 100 parts of ethanol to prepare a mixed coupling agent solution; nano-silica is added to the mixed coupling agent solution at a weight ratio of 1:5-15, and ultrasonically dispersed at 70-80℃ for 1-2 hours; then the treated mixture is filtered and separated, and the obtained solid material is dried and ground to obtain the surface-modified nano-silica.

[0013] Explanation: A treatment solution was prepared by combining silane coupling agent KH-570 and titanate coupling agent NDZ-201, dissolved in ethanol. Utilizing their synergistic effect, a more efficient and complete organic coating of nano-silica surfaces was achieved. Ultrasonic treatment at 70-80℃ for 1-2 hours with a solid-liquid ratio of 1:5-15 ensured sufficient wetting and dispersion of the nanoparticles in the liquid phase, as well as sufficient reaction and grafting of the coupling agent on the surface. This method significantly improves the dispersion stability and interfacial bonding of nano-silica in polyolefin matrices, which is a prerequisite for its reinforcing and toughening effects.

[0014] Further, by weight, the raw material ratio of the inner sheath layer masterbatch in S3 is: 100 parts thermoplastic polyurethane, 15-25 parts polyether ester elastomer, 3-6 parts short-cut PBO fibers with a length of 2-4 mm, 2-4 parts carbon nanotubes, and 0.3-0.8 parts ultraviolet light stabilizer.

[0015] Description: Using 100 parts thermoplastic polyurethane (TPU) as the matrix, 15-25 parts polyether ester elastomer are added to improve low-temperature flexibility. 3-6 parts short-cut PBO fibers (2-4 mm) and 2-4 parts carbon nanotubes constitute a micro-nano reinforcement system. PBO fibers provide extremely high modulus and strength, while carbon nanotubes effectively transfer stress, inhibit microcracks, and improve the material's abrasion resistance and electrical / thermal conductivity uniformity. The addition of 0.3-0.8 parts UV stabilizer ensures the material's long-term stability in outdoor environments. This formulation gives the inner sheath layer high toughness, high modulus, abrasion resistance, and excellent fatigue resistance.

[0016] Furthermore, the short-cut PBO fibers described in S3 are subjected to oxygen low-temperature plasma treatment before blending, with a treatment power of 300-400W, a temperature of 20-60℃, and a time of 1-3 min.

[0017] Note: Treating PBO fibers with 300-400W oxygen plasma at a low temperature of 20-60℃ for 1-3 minutes can introduce oxygen-containing polar groups (such as -COOH, -OH) onto the fiber surface without damaging the fiber's inherent strength, resulting in a micro-coarsening effect. This significantly enhances the interfacial wettability and chemical bonding between the PBO fibers and the TPU / polyether ester matrix, thereby greatly improving the stress transfer efficiency between the fiber and the matrix and fully utilizing the reinforcing potential of the PBO fibers. This is crucial for preventing the sheath layer from failing due to fiber-matrix debonding during bending.

[0018] Further, by weight, the raw material ratio of the outer sheath layer masterbatch in S3 is: 100 parts of chlorinated polyethylene, 10-20 parts of nitrile rubber, 20-35 parts of aluminum hydroxide, 5-10 parts of short-cut aramid fibers with a length of 3-6 mm, and 1-3 parts of silicone masterbatch.

[0019] Description: Using 100 parts of chlorinated polyethylene (CPE) as the matrix, 10-20 parts of nitrile rubber (NBR) are introduced to improve flexibility and oil resistance, 20-35 parts of aluminum hydroxide are used as an environmentally friendly flame retardant, and 1-3 parts of silicone masterbatch are added to improve processability. This formulation system allows the outer sheath layer to maintain good flame retardancy and processability through aluminum hydroxide, while obtaining excellent cut resistance, tear resistance and abrasion resistance through the reinforcement of 5-10 parts of aramid fiber. It also forms a gradient transition in function and modulus with the inner sheath layer, and together they bear external mechanical stress.

[0020] Further, the cable composite and final forming method in S4 is as follows: 7-19 composite conductor monofilaments are concentrically twisted around a filler rope with a twist pitch ratio of 10-14 to obtain a conductor core; the insulation masterbatch is extruded around the conductor core at 150-185°C to form an insulated core; an adhesive layer is coated on the surface of the insulated core with a thickness of 0.01-0.03 mm; the inner sheath masterbatch and outer sheath masterbatch obtained in S3 are melt-plasticized separately through two independent extruders; the two extruders are connected together in a coaxial double-layer co-extrusion gyroscope. A rotating die head extrudes melt from the inner sheath masterbatch through the inner flow channel to form the inner sheath layer, and extrudes melt from the outer sheath masterbatch through the outer flow channel to form the outer sheath layer; the extruded thickness of the inner sheath layer is 0.3-0.8 mm, and the extruded thickness of the outer sheath layer is 0.8-1.5 mm; the insulated wire core coated with adhesive is passed through the central hole of the die head; while the insulated wire core is pulled forward, the melt temperature of the inner sheath layer is controlled at 185-195℃, the melt temperature of the outer sheath layer is controlled at 165-175℃, and the die head temperature is controlled at 175-185℃, and the double-layer die head is driven to rotate around its axis at a speed of 20-50 rpm; In this process, the inner sheath melt first coats the surface of the insulated core, and then the outer sheath melt coats the outside of the inner sheath. The two melts cool and solidify simultaneously, and due to the rotation of the die, the short-cut fibers (PBO fibers and aramid fibers) form a specific spatial orientation in the melt, ultimately forming a double-layer gradient outer sheath with a fiber-reinforced structure around the cable, thus obtaining the cable blank. The cable blank is then subjected to two-stage cooling and shaping through a 90-100℃ warm water bath and a 20-30℃ cooling water bath, and finally wound up to obtain the finished cable.

[0021] Description: The cable core employs a stranded structure with 7-19 conductor filaments and a pitch ratio of 10-14, ensuring both flexibility and structural stability. The insulation layer is extruded at 150-185℃, ensuring excellent molding and adhesion. A key innovation lies in the use of coaxial double-layer co-extrusion rotary die technology. With precise melt temperature control and a die speed of 20-50 rpm, the reinforcing fibers PBO and aramid in the inner and outer sheaths form a specific spatially oriented interwoven structure along the cable's axial and circumferential directions at the melt solidification front. This structure mimics the reinforcement method of biocomposite materials, enabling the sheath layer to uniformly bear multi-directional bending stress, significantly improving fatigue resistance. Subsequent two-stage cooling with 90-100℃ warm water and 20-30℃ cold water effectively reduces internal stress, prevents defects caused by excessively rapid crystallization, and stabilizes the sheath's dimensions and performance.

[0022] Further, the adhesive in S4 is a mixed solution of hydrogenated petroleum resin and polyisobutylene dissolved in an organic solvent, wherein the mass ratio of hydrogenated petroleum resin to polyisobutylene is 1-9:1, and the organic solvent is selected from aromatic hydrocarbon, alkane or cycloalkane solvents; the mass concentration of the mixed solution is 10-50%; the coating thickness is 0.01-0.03 mm; the filler rope is made of thermoplastic polyurethane (TPU) or ethylene propylene diene monomer (EPDM) rubber with a Shore A hardness of 70-90.

[0023] Description: The adhesive is prepared by dissolving hydrogenated petroleum resin and polyisobutylene in aromatic / alkanes / cycloalkanes to form a 10-50% concentration solution. The hydrogenated petroleum resin provides high initial tack and heat resistance, while the polyisobutylene imparts lasting flexibility and cohesive strength. The ratio of the two can be adjusted to meet different bonding requirements. A dry film thickness of 0.01-0.03 mm is sufficient to form an effective adhesive layer without affecting cable flexibility. The center filler cord is made of TPU or EPDM with a Shore A hardness of 70-90. This hardness range provides sufficient support during stranding to maintain the roundness of the cable core, while also possessing good elasticity to absorb some compressive stress during bending, preventing excessive deformation of the conductor filaments.

[0024] Furthermore, in S4, after the cable blank undergoes two-stage cooling and shaping, the cooled and shaped cable blank is subjected to electron beam irradiation crosslinking treatment using an industrial electron accelerator. The irradiation energy is controlled at 1.0-1.5 MeV, the beam current intensity is controlled at 5-15 mA, and the production line traction speed is controlled at 20-60 m / min. By adjusting the line speed, the cumulative irradiation dose of the cable blank is stabilized at 30-50 kGy. After irradiation, the gel content of the insulation layer and sheath layer of the cable blank is 70-85%.

[0025] Explanation: After cooling and shaping, the cable blank is irradiated with an electron beam. By controlling the electron beam energy, beam current intensity, and production traction speed, the cumulative absorbed dose is precisely controlled within 30-50 kGy. This dose range is optimized; too low a dose results in insufficient cross-linking and limited performance improvement, while too high a dose may lead to polymer degradation. Irradiation causes cross-linking of polymer molecules in the insulation and sheath layers, forming a three-dimensional network structure. Stable control of the gel content after cross-linking at 70-85% indicates that the material has achieved a suitable cross-linking density. This brings significant benefits: greatly improving the material's heat distortion temperature, mechanical strength, resistance to environmental stress cracking, and dimensional stability, enabling the cable to withstand harsher operating temperatures and environments, and achieving a longer service life. Furthermore, treatment at room temperature does not affect the cable's already formed structure.

[0026] The beneficial effects of this invention are: This invention utilizes precision metallurgical processes to prepare the core conductor. A high-toughness aluminum-magnesium-silicon-copper alloy is used as the inner core, and a high-conductivity aluminum-magnesium-silicon-scandium-zirconium alloy is used as the outer conductor layer. Nano-alumina is introduced between the two to strengthen the interface. Metallurgical bonding of the three layers is achieved through hot isostatic pressing, followed by temperature-controlled drawing and multi-stage aging treatment, resulting in a composite conductor monofilament with high toughness, high conductivity, and excellent fatigue resistance. This fundamentally solves the problem of increased resistance due to microcracks formed during repeated bending. Secondly, for the insulation layer, a polyolefin elastomer is used as the matrix, with specifically modified nano-silica added. A crosslinking agent is simultaneously injected during twin-screw extrusion to achieve in-situ dynamic crosslinking, thereby obtaining a crosslinked insulation masterbatch with extremely high flexibility and tear resistance. To ensure the insulation layer can bend synchronously with the conductor without breaking, an innovative double-layer fiber-reinforced gradient structure is designed for the outer sheath: the inner layer is based on thermoplastic polyurethane, composite with chopped PBO fibers and carbon nanotubes; the outer layer is based on chlorinated polyethylene, composite with chopped aramid fibers and flame retardants. A coaxial double-layer co-extrusion rotary die technology is employed, rotating the die while extruding and coating, causing the reinforcing fibers in the inner and outer layers to interweave axially and circumferentially along the cable axis, forming a three-dimensional reinforcement network. This gives the sheath excellent radial compressive strength, circumferential torsional strength, and overall fatigue resistance. During the cable forming stage, the composite conductor is stranded, a flexible insulation layer is extruded, and a special adhesive is applied. Then, the composite conductor is introduced into the aforementioned rotary co-extrusion process to simultaneously form the gradient outer sheath, which is then cooled and shaped using an optimized temperature control design.

[0027] Through the synergistic effect of each step, the cable produced by this method exhibits an extremely long service life, stable low resistance characteristics, reliable insulation performance, and excellent environmental adaptability, even under extremely frequent small-radius bending conditions, fully meeting the stringent requirements of automated drone charging stations for power supply cables. Attached Figure Description

[0028] Figure 1 This is a bar chart comparing the bending fatigue life performance of samples from Examples 1-17 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0029] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0030] Example 1: A method for preparing a bend-resistant aluminum alloy low-voltage cable for drone charging stations includes the following steps: S1. Preparation of composite structure conductor single wire: S1-1. By mass percentage, 1.1% magnesium, 0.4% copper, 0.2% silicon and the balance aluminum are melted and cast into round bars to obtain an alloy core; 0.6% magnesium, 0.1% scandium, 0.15% zirconium and the balance aluminum are melted and cast to obtain a tube blank. S1-2. γ-alumina powder with an average particle size of 70-80 nm is dispersed in a binder solution to form a slurry, which is then coated onto the outer surface of the alloy inner core. After drying, it is assembled into the tube blank and hot isostatically laminated at 500℃ and 125 MPa argon atmosphere for 1.5 h to form a composite ingot. The binder solution is an ethanol solution containing 4% polyvinyl butyral by mass, the slurry has a solid content of 15% by mass, and the coating thickness is 170 μm. S1-3. The composite ingot has a diameter of 10 mm. It is first hot-drawn at 400℃, then drawn in four passes to a diameter of 4 mm, with annealing at 320℃ in a hydrogen-containing atmosphere for 10 min between each pass. It is then cooled to room temperature and cold-drawn in five passes to a target diameter of 1.0 mm, with annealing at 320℃ in a hydrogen-containing atmosphere for 10 min between each pass to relieve stress. The resulting monofilament is then subjected to a two-stage aging treatment to obtain a composite structure conductor monofilament. In the two-stage aging treatment: the first stage temperature is 110℃, and the holding time is 12.5 h; the second stage temperature is 160℃, and the holding time is 8 h. The hydrogen-containing atmosphere is an argon-hydrogen mixture with a hydrogen volume percentage of 8% and the remainder being argon. S2. Preparation of insulating layer masterbatch: By weight, 100 parts of polyolefin elastomer, 25 parts of maleic anhydride-grafted polyolefin, 8 parts of hydrogenated styrene elastomer, 10 parts of surface-modified nano-silica, and 0.5 parts of antioxidant are melt-blended. The blend is then melt-conveyed through a twin-screw extruder at 160°C. A peroxide crosslinking agent, accounting for 0.8% of the total material weight, is injected into the rear section of the barrel. The in-situ dynamic crosslinking reaction is completed using the shearing and mixing action generated by the screw assembly. The resulting material is then pelletized underwater to obtain the insulating layer masterbatch. The preparation method of the surface-modified nano-silica is as follows: By weight, 2 parts of... Silane coupling agent KH-570 and 1 part titanate coupling agent NDZ-201 were dissolved in 100 parts ethanol to prepare a mixed coupling agent solution. Nano-silica was added to the mixed coupling agent solution at a weight ratio of 1:10 and ultrasonically dispersed at 75°C for 1.5 hours. The treated mixture was then filtered and separated, and the resulting solid material was dried and ground to obtain the surface-modified nano-silica. The antioxidant was a mixture of commercially available antioxidant 1010 and antioxidant 168 at a mass ratio of 1:1, and the peroxide crosslinking agent was dicumyl peroxide (DCP). S3. Preparation of sheath layer masterbatch: Based on the weight percentages, 100 parts by weight of thermoplastic polyurethane, 20 parts by weight of polyether ester elastomer, 4 parts by weight of short-cut PBO fibers with a length of 2.5-3.5 mm, 3 parts by weight of carbon nanotubes, and 0.5 parts by weight of UV stabilizer are melt-blended and granulated to obtain the inner sheath layer masterbatch. Based on the weight percentages, 100 parts by weight of chlorinated polyethylene, 15 parts by weight of nitrile rubber, 30 parts by weight of aluminum hydroxide, 8 parts by weight of short-cut aramid fiber with a length of 4-5 mm and 2 parts by weight of silicone masterbatch are melt-blended and granulated to obtain the outer sheath layer masterbatch. S4. Cable Composite and Final Molding: Twelve composite conductor monofilaments are concentrically twisted around a filler rope with a twisting pitch ratio of 12 to obtain a conductor core. The insulation masterbatch is extruded over the conductor core at 165°C to form an insulated core. An adhesive layer with a thickness of 0.02 mm is coated onto the surface of the insulated core. The inner sheath masterbatch and outer sheath masterbatch obtained in S3 are melt-plasticized separately through two independent extruders. The two extruders are connected to a coaxial double-layer co-extrusion rotary die, with the inner laminar flow... The inner sheath layer is formed by extruding melt from the inner sheath masterbatch, and the outer sheath layer is formed by extruding melt from the outer sheath masterbatch. The inner sheath layer has an extrusion thickness of 0.5 mm, and the outer sheath layer has an extrusion thickness of 1.0 mm. The insulated wire core coated with adhesive is passed through the central hole of the die head. While the insulated wire core is pulled forward, the inner sheath layer melt temperature is controlled at 190°C, the outer sheath layer melt temperature at 170°C, and the die head temperature at 180°C. The double-layer die head is driven to rotate around its axis at a speed of 35 rpm. In this process, the inner sheath melt first coats the surface of the insulated core, and then the outer sheath melt coats the outside of the inner sheath. The two melts cool and solidify simultaneously. Due to the rotation of the die, the chopped fibers (PBO fibers and aramid fibers) form a specific spatial orientation in the melt, ultimately forming a double-layer gradient outer sheath with a fiber-reinforced structure around the cable, resulting in a cable blank. The cable blank is then subjected to two-stage cooling and shaping through a 95°C warm water bath and a 25°C cooling water bath, and finally wound up to obtain the finished cable. The adhesive is a mixed solution of hydrogenated petroleum resin and polyisobutylene dissolved in an organic solvent, wherein the mass ratio of hydrogenated petroleum resin to polyisobutylene is 4.5:1, and the organic solvent is selected from aromatic solvents; the mass concentration of the mixed solution is 30%; the coating thickness is 0.02 mm; the filler rope is made of thermoplastic polyurethane (TPU) with a Shore A hardness of 80.

[0031] Example 2: This example is basically the same as Example 1, except that the short-cut PBO fibers in S3 are treated with oxygen low-temperature plasma before blending. The treatment power is 350W, the temperature is 40℃, and the time is 2 min.

[0032] Example 3: This example is basically the same as Example 1, except that the short-cut PBO fibers in S3 are treated with oxygen low-temperature plasma before blending. The treatment power is 300W, the temperature is 20℃, and the time is 1 min.

[0033] Example 4: This example is basically the same as Example 1, except that the short-cut PBO fibers in S3 are treated with oxygen low-temperature plasma before blending. The treatment power is 400W, the temperature is 60℃, and the time is 3 min.

[0034] Example 5: This example is basically the same as Example 1, except that in S4, after the cable blank is cooled and shaped in two stages, it is further subjected to electron beam irradiation crosslinking treatment. An industrial electron accelerator is used, the irradiation energy is controlled at 1.2 MeV, the beam current intensity is controlled at 10 mA, and the production line traction speed is controlled at 40 m / min. By adjusting the line speed, the cumulative irradiation dose of the cable blank is stabilized at 40 kGy. After irradiation, the gel content of the insulation layer and sheath layer of the cable blank is 80%.

[0035] Example 6: This example is basically the same as Example 1, except that in S4, after the cable blank is cooled and shaped in two stages, it is further subjected to electron beam irradiation crosslinking treatment. An industrial electron accelerator is used, the irradiation energy is controlled at 1.0 MeV, the beam current intensity is controlled at 5 mA, and the production line traction speed is controlled at 20 m / min. By adjusting the line speed, the cumulative irradiation dose of the cable blank is stabilized at 30 kGy. After irradiation, the gel content of the insulation layer and sheath layer of the cable blank is 70%.

[0036] Example 7: This example is basically the same as Example 1, except that in S4, after the cable blank is cooled and shaped in two stages, it is further subjected to electron beam irradiation crosslinking treatment. An industrial electron accelerator is used, the irradiation energy is controlled at 1.5 MeV, the beam current intensity is controlled at 15 mA, and the production line traction speed is controlled at 60 m / min. By adjusting the line speed, the cumulative irradiation dose of the cable blank is stabilized at 50 kGy. After irradiation, the gel content of the insulation layer and sheath layer of the cable blank is 85%.

[0037] Example 8: This example is basically the same as Example 1, except that it includes the following steps: S1. Preparation of composite structure conductor single wire: S1-1. By mass percentage, aluminum ingots containing 0.8% magnesium, 0.2% copper, and 0.1% silicon are melted and cast into round bars to obtain an alloy core; aluminum ingots containing 0.4% magnesium, 0.08% scandium, and 0.10% zirconium are melted and cast to obtain a tube blank. S1-2. γ-alumina powder with an average particle size of 50-60 nm is dispersed in a binder solution to form a slurry, which is then coated onto the outer surface of the alloy inner core. After drying, it is assembled into the tube blank and hot isostatically laminated at 480℃ and 100MPa argon atmosphere for 1 h to form a composite ingot. The binder solution is an ethanol solution containing 3% polyvinyl butyral by mass, the slurry has a solid content of 10% by mass, and the coating thickness is 100 μm. S1-3. The composite ingot has a diameter of 8 mm. It is first hot-drawn at 380℃, and then drawn in 3 passes to a diameter of 3 mm. Between each pass, it is annealed in a hydrogen-containing atmosphere at 300℃ for 8 min. Then, it is cooled to room temperature and cold-drawn in 4 passes to a target diameter of 0.8 mm. Between each pass, it is also annealed in a hydrogen-containing atmosphere at 300℃ for 8 min to relieve stress. Then, the obtained monofilament is subjected to a two-stage aging treatment to obtain a composite structure conductor monofilament. In the two-stage aging treatment: the temperature of the first stage is 100℃ and the holding time is 10 h; the temperature of the second stage is 150℃ and the holding time is 5 h. S2. Preparation of insulating layer masterbatch: By weight, 100 parts of polyolefin elastomer, 20 parts of maleic anhydride-grafted polyolefin, 5 parts of hydrogenated styrene elastomer, 8 parts of surface-modified nano-silica, and 0.3 parts of antioxidant are melt-blended. The blend is then melt-conveyed through a twin-screw extruder at 155°C. A peroxide crosslinking agent, accounting for 0.5% of the total material weight, is injected into the rear section of the barrel. The in-situ dynamic crosslinking reaction is completed using the shearing and mixing action generated by the screw assembly. The resulting material is then pelletized underwater to obtain the insulating layer masterbatch. The preparation method of surface-modified nano-silica is as follows: 1 part by weight of silane coupling agent KH-570 and 0.5 parts by weight of titanate coupling agent NDZ-201 are dissolved in 100 parts by weight of ethanol to prepare a mixed coupling agent solution; nano-silica is added to the mixed coupling agent solution at a weight ratio of 1:5, and ultrasonically dispersed at 70°C for 1 hour; the treated mixture is then filtered and separated, and the resulting solid material is dried and ground to obtain the surface-modified nano-silica; S3. Preparation of sheath layer masterbatch: Based on the weight percentages, 100 parts by weight of thermoplastic polyurethane, 15 parts by weight of polyether ester elastomer, 3 parts by weight of short-cut PBO fibers with a length of 2-3 mm, 2 parts by weight of carbon nanotubes and 0.3 parts by weight of UV stabilizer are melt-blended and granulated to obtain the inner sheath layer masterbatch. Based on the weight percentages, 100 parts by weight of chlorinated polyethylene, 10 parts by weight of nitrile rubber, 20 parts by weight of aluminum hydroxide, 5 parts by weight of short-cut aramid fiber with a length of 3-4 mm and 1 part by weight of silicone masterbatch are melt-blended and granulated to obtain the outer sheath layer masterbatch. S4. Cable Composite and Final Molding: Seven composite conductor monofilaments are concentrically twisted around a filler rope with a twist pitch ratio of 10 to obtain a conductor core. The insulation masterbatch is extruded over the conductor core at 150°C to form an insulated core. An adhesive layer with a thickness of 0.01 mm is coated onto the surface of the insulated core. The inner sheath masterbatch and outer sheath masterbatch obtained in S3 are melt-plasticized separately through two independent extruders. The two extruders are connected to a coaxial double-layer co-extrusion rotary die, with the inner laminar flow... The inner sheath layer is formed by extruding melt from the inner sheath masterbatch, and the outer sheath layer is formed by extruding melt from the outer sheath masterbatch. The inner sheath layer has an extrusion thickness of 0.3 mm, and the outer sheath layer has an extrusion thickness of 0.8 mm. The insulated wire core coated with adhesive is passed through the central hole of the die head. While the insulated wire core is pulled forward, the inner sheath layer melt temperature is controlled at 185°C, the outer sheath layer melt temperature at 165°C, and the die head temperature at 175°C. The double-layer die head is driven to rotate around its axis at a speed of 20 rpm. In this process, the inner sheath melt first coats the surface of the insulated core, and then the outer sheath melt coats the outside of the inner sheath. The two melts cool and solidify simultaneously. Due to the rotation of the die, the chopped fibers (PBO fibers and aramid fibers) form a specific spatial orientation in the melt, ultimately forming a double-layer gradient outer sheath with a fiber-reinforced structure around the cable, resulting in a cable blank. The cable blank is then subjected to two stages of cooling and shaping, passing through a 90°C warm water bath and a 20°C cooling water bath, and finally wound up to obtain the finished cable. The adhesive is a mixed solution of hydrogenated petroleum resin and polyisobutylene dissolved in an organic solvent, wherein the mass ratio of hydrogenated petroleum resin to polyisobutylene is 1:1, and the organic solvent is selected from alkane solvents; the mass concentration of the mixed solution is 10%; the coating thickness is 0.01 mm; the filler rope is made of ethylene propylene diene monomer (EPDM) rubber with a Shore A hardness of 70.

[0038] Example 9: This example is basically the same as Example 1, except that it includes the following steps: S1. Preparation of composite structure conductor single wire: S1-1. By mass percentage, 1.5% magnesium, 0.6% copper, 0.3% silicon and the balance aluminum are melted and cast into round bars to obtain an alloy core; 0.9% magnesium, 0.15% scandium, 0.20% zirconium and the balance aluminum are melted and cast to obtain a tube blank. S1-2. γ-alumina powder with an average particle size of 90-100 nm is dispersed in a binder solution to form a slurry, which is then coated onto the outer surface of the alloy inner core. After drying, it is assembled into the tube blank and hot isostatically laminated at 520℃ and 150 MPa argon atmosphere for 2 h to form a composite ingot. The binder solution is an ethanol solution containing 5% polyvinyl butyral by mass, the slurry has a solid content of 20% by mass, and the coating thickness is 200 μm. S1-3. The composite ingot has a diameter of 12 mm. It is first hot-drawn at 450℃, and then drawn to a diameter of 4 mm in 5 passes, with annealing in a hydrogen-containing atmosphere at 350℃ for 12 min between each pass. Then it is cooled to room temperature and cold-drawn, and then drawn to a target diameter of 1.0 mm in 10 passes, with annealing in a hydrogen-containing atmosphere at 350℃ for 12 min between each pass to relieve stress. Then the obtained monofilament is subjected to a two-stage aging treatment to obtain a composite structure conductor monofilament. In the two-stage aging treatment: the temperature of the first stage is 120℃ and the holding time is 15 h, and the temperature of the second stage is 170℃ and the holding time is 10 h. S2. Preparation of insulating layer masterbatch: By weight, 100 parts of polyolefin elastomer, 30 parts of maleic anhydride-grafted polyolefin, 10 parts of hydrogenated styrene elastomer, 15 parts of surface-modified nano-silica, and 0.8 parts of antioxidant are melt-blended. The blend is then melt-conveyed through a twin-screw extruder at 170°C. A peroxide crosslinking agent, accounting for 1.0% of the total material weight, is injected into the rear section of the barrel. The in-situ dynamic crosslinking reaction is completed using the shearing and mixing action generated by the screw assembly. The resulting material is then pelletized underwater to obtain the insulating layer masterbatch. The preparation method of the surface-modified nano-silica is as follows: 3 parts by weight of silane coupling agent KH-570 and 1.5 parts by weight of titanate coupling agent NDZ-201 are dissolved in 100 parts by weight of ethanol to prepare a mixed coupling agent solution; nano-silica is added to the mixed coupling agent solution at a weight ratio of 1:15, and ultrasonically dispersed at 80°C for 2 hours; the treated mixture is then filtered and separated, and the resulting solid material is dried and ground to obtain the surface-modified nano-silica. S3. Preparation of sheath layer masterbatch: Based on the weight percentage, 100 parts by weight of thermoplastic polyurethane, 25 parts by weight of polyether ester elastomer, 6 parts by weight of short-cut PBO fibers with a length of 3-4 mm, 4 parts by weight of carbon nanotubes and 0.8 parts by weight of UV stabilizer are melt-blended and granulated to obtain the inner sheath layer masterbatch. Based on the weight percentages, 100 parts by weight of chlorinated polyethylene, 20 parts by weight of nitrile rubber, 35 parts by weight of aluminum hydroxide, 10 parts by weight of short-cut aramid fiber with a length of 5-6 mm and 3 parts by weight of silicone masterbatch are melt-blended and granulated to obtain the outer sheath layer masterbatch. S4. Cable Composite and Final Molding: Nineteen composite conductor monofilaments are concentrically twisted around a filler rope with a twist pitch ratio of 14 to obtain a conductor core. The insulation masterbatch is extruded over the conductor core at 185°C to form an insulated core. An adhesive layer with a thickness of 0.03 mm is coated onto the surface of the insulated core. The inner sheath masterbatch and outer sheath masterbatch obtained in S3 are melt-plasticized separately through two independent extruders. The two extruders are connected to a coaxial double-layer co-extrusion rotary die, with the inner laminar flow... The inner sheath layer is formed by extruding melt from the inner sheath masterbatch, and the outer sheath layer is formed by extruding melt from the outer sheath masterbatch. The inner sheath layer has an extrusion thickness of 0.8 mm, and the outer sheath layer has an extrusion thickness of 1.5 mm. The insulated wire core coated with adhesive is passed through the central hole of the die head. While the insulated wire core is pulled forward, the inner sheath layer melt temperature is controlled at 195°C, the outer sheath layer melt temperature at 175°C, and the die head temperature at 185°C. The double-layer die head is driven to rotate around its axis at a speed of 50 rpm. In this process, the inner sheath melt first coats the surface of the insulated core, and then the outer sheath melt coats the outside of the inner sheath. The two melts cool and solidify simultaneously. Due to the rotation of the die head, the chopped fibers (PBO fibers and aramid fibers) form a specific spatial orientation in the melt, ultimately forming a double-layer gradient outer sheath with a fiber-reinforced structure around the cable, resulting in a cable blank. The cable blank is then subjected to two stages of cooling and shaping, passing through a 100°C warm water bath and a 30°C cooling water bath, and finally wound up to obtain the finished cable. The adhesive is a mixed solution of hydrogenated petroleum resin and polyisobutylene dissolved in an organic solvent, wherein the mass ratio of hydrogenated petroleum resin to polyisobutylene is 9:1, and the organic solvent is selected from cycloalkane solvents; the mass concentration of the mixed solution is 50%; the coating thickness is 0.03 mm; the filler rope is made of thermoplastic polyurethane (TPU) with a Shore A hardness of 90.

[0039] Example 10: This example is basically the same as Example 1, except that the adhesive solution in S1-2 is an ethanol solution containing 3% polyvinyl butyral by mass, the slurry has a solid content of 10% by mass, and the coating thickness is 100μm; in the two-stage aging treatment in S1-3: the temperature of the first stage is 100℃ and the holding time is 10 h, and the temperature of the second stage is 150℃ and the holding time is 5 h.

[0040] Example 11: This example is basically the same as Example 1, except that the adhesive solution in S1-2 is an ethanol solution containing 5% polyvinyl butyral by mass, the slurry has a solid content of 20% by mass, and the coating thickness is 200μm; in the two-stage aging treatment in S1-3: the temperature of the first stage is 120℃ and the holding time is 15 h, and the temperature of the second stage is 170℃ and the holding time is 10 h.

[0041] Example 12: This example is basically the same as Example 1, except that, by weight, the raw material ratio of the insulating layer masterbatch in S2 is: 100 parts of polyolefin elastomer, 20 parts of maleic anhydride grafted polyolefin, 5 parts of hydrogenated styrene elastomer, 8 parts of surface-modified nano silica, and 0.3 parts of antioxidant.

[0042] Example 13: This example is basically the same as Example 1, except that, by weight, the raw material ratio of the insulating layer masterbatch in S2 is: 100 parts of polyolefin elastomer, 30 parts of maleic anhydride grafted polyolefin, 10 parts of hydrogenated styrene elastomer, 15 parts of surface-modified nano silica, and 0.8 parts of antioxidant.

[0043] Example 14: This example is basically the same as Example 1, except that the preparation method of the surface-modified nano silica in S2 is as follows: by weight, 1 part of silane coupling agent KH-570 and 0.5 parts of titanate coupling agent NDZ-201 are dissolved together in 100 parts of ethanol to prepare a mixed coupling agent solution; nano silica is added to the mixed coupling agent solution at a weight ratio of 1:5, and ultrasonically dispersed at 70°C for 1 hour; then the treated mixture is filtered and separated, and the obtained solid material is dried and ground to obtain the surface-modified nano silica.

[0044] Example 15: This example is basically the same as Example 1, except that the preparation method of the surface-modified nano silica in S2 is as follows: by weight, 3 parts of silane coupling agent KH-570 and 1.5 parts of titanate coupling agent NDZ-201 are dissolved together in 100 parts of ethanol to prepare a mixed coupling agent solution; nano silica is added to the mixed coupling agent solution at a weight ratio of 1:15, and ultrasonically dispersed at 80°C for 2 hours; then the treated mixture is filtered and separated, and the obtained solid material is dried and ground to obtain the surface-modified nano silica.

[0045] Example 16: This example is basically the same as Example 1, except that, by weight, the raw material ratio of the inner sheath layer masterbatch in S3 is as follows: 100 parts by weight of thermoplastic polyurethane, 15 parts by weight of polyether ester elastomer, 3 parts by weight of short-cut PBO fibers with a length of 2-3 mm, 2 parts by weight of carbon nanotubes, and 0.3 parts by weight of UV stabilizer are melt-blended and granulated; by weight, the raw material ratio of the outer sheath layer masterbatch in S3 is as follows: 100 parts by weight of chlorinated polyethylene, 10 parts by weight of nitrile rubber, 20 parts by weight of aluminum hydroxide, 5 parts by weight of short-cut aramid fibers with a length of 3-4 mm, and 1 part by weight of silicone masterbatch are melt-blended and granulated.

[0046] Example 17: This example is basically the same as Example 1, except that, by weight, the raw material ratio of the inner sheath layer masterbatch in S3 is as follows: 100 parts by weight of thermoplastic polyurethane, 25 parts by weight of polyether ester elastomer, 6 parts by weight of short-cut PBO fibers with a length of 3-4 mm, 4 parts by weight of carbon nanotubes, and 0.8 parts by weight of UV stabilizer are melt-blended and granulated; by weight, the raw material ratio of the outer sheath layer masterbatch in S3 is as follows: 100 parts by weight of chlorinated polyethylene, 20 parts by weight of nitrile rubber, 35 parts by weight of aluminum hydroxide, 10 parts by weight of short-cut aramid fibers with a length of 5-6 mm, and 3 parts by weight of silicone masterbatch are melt-blended and granulated.

[0047] Comparative Example 1: The manufacturing method of AA8030 series aluminum alloy low-voltage cable for drone charging piles, which is commonly used in the industry, is adopted. The specific steps are as follows: 1.0 mm conductor monofilaments are obtained by drawing AA8030 aluminum alloy rods. 12 monofilaments are concentrically twisted around TPU filler rope with a pitch ratio of 12 to obtain the conductor core. Commercially available general-purpose ethylene propylene rubber insulation material is extruded at 165℃ to form an insulated wire core. Commercially available general-purpose chlorinated polyethylene sheathing material is used to extrude a sheath on the outside of the insulated wire core through a conventional single-layer extrusion process. After cooling and shaping in 95℃ warm water, the cable is wound up to obtain the finished cable.

[0048] Comparative Example 2: This comparative example is basically the same as Example 1, except that the preparation step of the composite structure conductor single wire of S1 is cancelled. Instead, the alloy core of S1-1 in Example 1 is directly used to obtain a single structure aluminum alloy conductor single wire of Φ1.0mm through melting and drawing. The remaining process steps and parameters are completely consistent with Example 1.

[0049] Comparative Example 3: This comparative example is basically the same as Example 1, except that the adhesive coating step on the surface of the insulated wire core in S4 is cancelled, and the coaxial double-layer co-extrusion rotary die process is not performed. Instead, a conventional two-step extrusion sheath is used. First, a single screw extruder is used to extrude the inner sheath layer on the outside of the insulated wire core. After cooling, the outer sheath layer is extruded. The extrusion die does not rotate. The remaining process steps and parameters are completely consistent with Example 1.

[0050] To investigate the cable performance of the above embodiments and control examples, the main materials were determined according to the experimental formula and samples were obtained for testing. The bending fatigue life was tested using a cable reciprocating bending tester with a bending radius of 5 times the outer diameter of the finished cable, a bending angle of ±90°, and a bending frequency of 30 times / min. The test was stopped when the conductor core broke or the insulation broke down, and the number of bends was recorded.

[0051] The peel force of the insulation layer interface was tested using a universal tensile testing machine, referring to the peel force test method specified in GB / T 2951.21-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers". The peel angle was 180°, the tensile speed was 50 mm / min, the sample width was 25 mm, and the average peel force was recorded.

[0052] The change rate of conductor resistance after bending was determined according to GB / T3048.4-2007 standard. The initial DC resistance at 20℃ and the DC resistance at 20℃ after 500,000 bends were tested respectively. The change rate of resistance was calculated as (resistance after bending - initial resistance) / initial resistance × 100%.

[0053] The insulation breakdown strength retention rate after bending was determined according to GB / T1408.1-2016 standard. The initial insulation breakdown strength and the insulation breakdown strength after 500,000 bends were tested separately. The retention rate was calculated as: (Bending breakdown strength / Initial breakdown strength) × 100%. The results are as follows: Figure 1 As shown in Table 1. The specific investigation is as follows: Table 1 Performance test table of cable samples from Examples 1-17 and Comparative Examples 1-3

[0054] 1. To explore the impact of changes in core structure and molding process on the operational reliability and bending resistance of cables: The aluminum alloy low-voltage cable for drone charging stations prepared by this invention exhibits significantly superior core performance in all embodiments compared to the prior art control example 1, as shown in Table 1. Figure 1As shown in Table 1, the composite conductor monofilament is the core foundation determining the cable's resistance to bending fatigue. Comparative Example 2 only eliminated the composite conductor design; the rest of the process was completely identical to Example 1. As shown in Table 1, its bending fatigue life decreased by 45.5% compared to Example 1, and the conductor resistance change rate after bending increased by approximately 213.6%. Comparative Example 3 eliminated the double-layer rotary co-extruded sheath and interface adhesive design. As shown in Table 1, its insulation layer interface peel force decreased by 65.7% compared to Example 1, and the insulation breakdown strength retention rate after bending decreased by 13.1%. This demonstrates that the synergistic effect of the composite conductor, interface adhesive design, and double-layer fiber-reinforced sheath is key to solving the core problems of conductor fatigue fracture and insulation peel failure; all three are indispensable.

[0055] 2. To investigate the impact of changes in the plasma treatment process for chopped PBO fibers on the bending fatigue resistance of cables: Low-temperature oxygen plasma treatment of chopped PBO fibers can effectively improve the overall performance of cables, as shown in Table 1. The sample treated with the parameters in Example 2 showed the best performance, while the sample treated with the parameters in Example 3 showed a relatively smaller performance improvement. The sample treated with the parameters in Example 4 showed a slight decrease in performance compared to Example 2. This is because moderate plasma treatment can introduce active groups and nanoscale rough structures on the fiber surface, enhancing the interfacial bonding between the fiber and the matrix. However, excessively high treatment power or prolonged treatment time can damage the fiber structure, thus weakening the reinforcing effect. The optimal treatment parameters of 350W, 40℃, and 2min demonstrate that this process maximizes the reinforcing effect of PBO fibers and improves the sheath's bending fatigue life.

[0056] 3. Investigate the impact of changes in the electron beam irradiation crosslinking process on the interface stability and insulation performance of cables: Electron beam irradiation crosslinking can significantly optimize the interfacial bonding stability and insulation protection performance of cables. As shown in Table 1, the sample in Example 5 using the intermediate irradiation parameters exhibits the best performance, the sample in Example 6 using the left-hand side parameters shows limited performance improvement, and the sample in Example 7 using the right-hand side parameters shows a slight decrease in performance compared to Example 5. This is because an irradiation dose of 30-50 kGy can stably control the gel content of the insulation and sheath layers within the optimal range of 70-85%. Insufficient dose leads to insufficient crosslinking degree, resulting in insufficient aging resistance and stress cracking resistance of the material. Excessive dose causes the material to become over-crosslinked and brittle, which in turn reduces bending resistance. This process completes crosslinking at room temperature without damaging the metallographic structure of the composite conductor, and can also stimulate the formation of chemical bonds by interfacial active groups, perfectly meeting the performance requirements of drone charging pile cables.

[0057] 4. Explore the impact of changes in the core process formulation parameter range on the overall performance and industrial adaptability of cables: The range settings for all process parameters in this invention are both reasonable and practical, as shown in Table 1. Figure 1 As shown, Example 1 exhibits significantly better overall performance than the other examples. Example 8, with its smaller formulation and process parameters, shows the worst performance. Example 9 performs slightly better than the sample at the left end but still worse than the sample in Example 1. This demonstrates that the parameter range defined in this invention represents the optimal controllable range for performance, achieving a perfect balance between conductivity, bending fatigue resistance, interfacial bonding, and weather resistance. As shown in Table 1, the core performance of all examples shows a stable improvement over existing technologies, with the conductor resistance change rate after bending controlled within 3.1%. This addresses the issue of insufficient operational reliability in high-frequency, small-radius bending scenarios for drone charging stations, demonstrating excellent industrial application value.

Claims

1. A method for preparing an aluminum alloy low-voltage cable for a bend-resistant unmanned aerial vehicle charging pile, characterized in that, Includes the following steps: S1. Preparation of composite structure conductor single wire: S1-1. By mass percentage, 0.8-1.5% magnesium, 0.2-0.6% copper, 0.1-0.3% silicon, and the balance aluminum are melted and cast into round bars to obtain an alloy inner core; 0.4-0.9% magnesium, 0.08-0.15% scandium, 0.10-0.20% zirconium, and the balance aluminum are melted and cast to obtain a tube blank; S1-2. Disperse γ-alumina powder with an average particle size of 50-100nm in a binder solution to form a slurry, coat it on the outer surface of the alloy core, dry it and assemble it into the tube blank, and hot isostatically press it at 480-520℃ and 100-150MPa argon atmosphere for 1-2 hours to form a composite ingot. S1-3. The composite ingot is first subjected to 3-5 passes of hot drawing, and then to 4-10 passes of cold drawing. Each pass is annealed in a hydrogen-containing protective atmosphere at 300-350℃. Finally, it is drawn to a conductor wire diameter of 0.8-1.5 mm. Then, it is subjected to two-stage aging treatment to obtain a composite structure conductor wire. S2. Preparation of insulating layer masterbatch: Polyolefin elastomer, maleic anhydride-grafted polyolefin, hydrogenated styrene elastomer, surface-modified nano silica and antioxidant are melt-blended; the blend is melt-conveyed through a twin-screw extruder at 155-170℃, and 0.5-1.0% of peroxide crosslinking agent by weight of the material is injected into the rear section of the barrel, and the insulating layer masterbatch is obtained by underwater pelletizing. S3. Preparation of sheath layer masterbatch: Thermoplastic polyurethane, polyether ester elastomer, chopped PBO fiber, carbon nanotube and ultraviolet light stabilizer are melt-blended and granulated to obtain inner sheath masterbatch; chlorinated polyethylene, nitrile rubber, aluminum hydroxide, chopped aramid fiber and silicone masterbatch are melt-blended and granulated to obtain outer sheath masterbatch. S4. Cable Composite and Final Molding: After stranding 7-19 composite conductor filaments into a cable core, insulation masterbatch is extruded over the cable core to obtain an insulated core. Then, an adhesive layer is coated on the surface of the insulated core, and the inner and outer sheaths are simultaneously wrapped through a coaxial double-layer co-extrusion rotary die to form a gradient outer sheath. Finally, after cooling and winding, an aluminum alloy low-voltage cable is obtained.

2. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 1, characterized in that, The adhesive solution mentioned in S1-2 is an ethanol solution containing 3-5% polyvinyl butyral by mass, the slurry has a solid content of 10-20% by mass, and the coating thickness is 100-200μm; in the two-stage aging treatment mentioned in S1-3: the temperature of the first stage is 100-120℃, and the holding time is 10-15 h; the temperature of the second stage is 150-170℃, and the holding time is 5-10 h.

3. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 1, characterized in that, By weight, the raw material ratio of the insulating layer masterbatch in S2 is as follows: 100 parts polyolefin elastomer, 20-30 parts maleic anhydride grafted polyolefin, 5-10 parts hydrogenated styrene elastomer, 8-15 parts surface-modified nano silica, and 0.3-0.8 parts antioxidant.

4. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 3, characterized in that, The preparation method of the surface-modified nano silica described in S2 is as follows: 1-3 parts by weight of silane coupling agent KH-570 and 0.5-1.5 parts by weight of titanate coupling agent NDZ-201 are dissolved together in 100 parts by weight to prepare a mixed coupling agent solution; nano silica is added to the mixed coupling agent solution at a weight ratio of 1:5-15, and ultrasonically dispersed at 70-80°C for 1-2 hours; the treated mixture is then filtered and separated, and the resulting solid material is dried and ground to obtain the surface-modified nano silica.

5. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 1, characterized in that, By weight, the raw material ratio of the inner sheath layer masterbatch in S3 is: 100 parts thermoplastic polyurethane, 15-25 parts polyether ester elastomer, 3-6 parts short-cut PBO fibers with a length of 2-4 mm, 2-4 parts carbon nanotubes, and 0.3-0.8 parts ultraviolet light stabilizer.

6. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 5, characterized in that, The short-cut PBO fibers described in S3 are treated with oxygen low-temperature plasma before blending, with a treatment power of 300-400W, a temperature of 20-60℃, and a time of 1-3 min.

7. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 1, characterized in that, By weight, the raw material ratio of the outer sheath layer masterbatch in S3 is: 100 parts chlorinated polyethylene, 10-20 parts nitrile rubber, 20-35 parts aluminum hydroxide, 5-10 parts short-cut aramid fibers with a length of 3-6 mm, and 1-3 parts silicone masterbatch.

8. The method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 1, characterized in that, The cable composite and final forming method in S4 is as follows: 7-19 composite conductor monofilaments are concentrically twisted around a filler rope with a twisting pitch ratio of 10-14 to obtain the conductor core; the insulation masterbatch is extruded around the conductor core at 150-185℃ to form an insulated core; an adhesive layer is coated on the surface of the insulated core; the inner sheath masterbatch and outer sheath masterbatch obtained in S3 are melted and plasticized separately through two independent extruders; the two extruders are connected to a coaxial double-layer co-extrusion rotary die, and the inner flow channel is extruded. The inner sheath layer is formed by extruding the melt from the inner sheath masterbatch, and the outer sheath layer is formed by extruding the melt from the outer sheath masterbatch through the outer flow channel. The extruded thickness of the inner sheath layer is 0.3-0.8 mm, and the extruded thickness of the outer sheath layer is 0.8-1.5 mm. The insulated core coated with adhesive is passed through the central hole of the die. While the insulated core is pulled forward, the temperature of the inner sheath melt is controlled at 185-195℃, the temperature of the outer sheath melt is controlled at 165-175℃, and the temperature of the die is controlled at 175-185℃. The double-layer die is driven to rotate around its axis at a speed of 20-50 rpm to obtain the cable blank. The cable blank is then subjected to two-stage cooling and shaping through a 90-100℃ warm water bath and a 20-30℃ cooling water bath. Finally, it is wound up to obtain the finished cable.

9. A method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 8, characterized in that, The adhesive described in S4 is a mixed solution of hydrogenated petroleum resin and polyisobutylene dissolved in an organic solvent, wherein the mass ratio of hydrogenated petroleum resin to polyisobutylene is 1-9:1, and the organic solvent is selected from aromatic hydrocarbon, alkane, or cycloalkane solvents; the mass concentration of the mixed solution is 10-50%; the coating thickness is 0.01-0.03 mm; and the filler rope is made of thermoplastic polyurethane or EPDM rubber with a Shore A hardness of 70-90.

10. A method for preparing a bend-resistant aluminum alloy low-voltage cable for a drone charging station according to claim 8, characterized in that, In S4, after the cable blank undergoes two-stage cooling and shaping, it also includes electron beam irradiation crosslinking treatment. This is carried out using an industrial electron accelerator, with the irradiation energy controlled at 1.0-1.5 MeV, the beam current intensity controlled at 5-15 mA, and the production line traction speed controlled at 20-60 m / min. By adjusting the line speed, the cumulative irradiation dose of the cable blank is stabilized at 30-50 kGy.

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