High strength cable and process for making same

Abstract

The application discloses a high-strength cable and a manufacturing process thereof, and relates to the technical field of cable manufacturing. The high-strength cable comprises, from inside to outside, a central force-bearing member, an inner conductive layer, an insulating layer, an outer conductive layer and a sheath layer. The core of the application is that the inner conductive layer is formed by asymmetric gradient twisting of a plurality of special-shaped conductors, the insulating layer is a composite nano-particle / polyether ether ketone composite layer, and the sheath layer is embedded with an axial elastic memory alloy wire. The application offsets the reverse torque of the inner and outer conductive layers, compensates the axial stress of the sheath layer through the self-healing mechanism of the insulating layer at high temperature, and improves the tensile strength and the repeated bending life to a new height while ensuring high conductivity.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, specifically to a high-strength cable and its manufacturing process. Background Technology

[0002] As a fundamental supporting industry of the national economy, cables are widely used in power transmission, signal communication, and various mobile equipment. With the development of robots, tethered drones, deep-sea exploration, and military equipment, cables need to withstand complex loads such as tension, bending, torsion, and impact during use, which places extremely high demands on their tensile strength, torsional fatigue resistance, and internal structural compactness.

[0003] In existing technologies, to improve cable strength, reinforcing cores or braided armor layers are typically incorporated into the cable, or reinforcing structures such as aramid fiber braided layers and tensile cotton ropes are used. At the materials level, existing technologies enhance the mechanical strength and corrosion resistance of the sheath layer by adding fillers such as nano-silica and glass fiber to the sheath layer, utilizing the hybrid cross-linking network between the additives and the matrix resin. Other technologies use carbon fiber-loaded hydrotalcite to reinforce fluororubber, producing high-strength overhead cable outer sheaths. Furthermore, cross-linked polyethylene materials can achieve a synergistic improvement in tensile strength and breakdown strength through the addition of nano-filler masterbatches.

[0004] However, existing high-strength cables still have the following technical defects: (1) Single material reinforcement method: Existing technologies mostly modify materials only for a single functional layer (such as the sheath layer), lacking a full gradient material system design from the central reinforcing core to the outer sheath. The mechanical properties of each layer of materials are poorly matched, resulting in low stress transfer efficiency.

[0005] (2) The contradiction between strength and flexibility is prominent: increasing strength by adding rigid fillers often comes at the cost of material flexibility. Although the strength of polyisobutylene materials can be improved by grafting with cage-type polysilsesquioxane, it is still difficult to meet the requirements of high strength and excellent flexibility at the same time.

[0006] (3) Insufficient phase dispersion and interfacial bonding: Nanofillers tend to agglomerate in the polymer matrix, and traditional coupling agent treatments are difficult to achieve the desired in-situ reinforcement effect. The interfacial bonding strength between carbon fiber and rubber matrix directly affects the overall mechanical properties of the composite material.

[0007] (4) Lack of self-sensing and self-repairing functions: The damage accumulated in the cable during long-term use cannot be detected and repaired in time, resulting in a high risk of sudden failure. Summary of the Invention

[0008] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a high-strength cable and its manufacturing process.

[0009] The technical solution of the present invention is as follows: A high-strength cable, comprising, from the inside out: The central load-bearing component is a carbon fiber composite mandrel or high-strength steel strand. The inner conductive layer is stranded to the outside of the central load-bearing component and is formed by stranding a first type of irregularly shaped conductor using a variable pitch and variable compression ratio. A composite insulating layer is wrapped around the outer surface of the inner conductive layer. It is made by extruding polyether ether ketone resin and composite nanoparticles after melt blending. Then, an alternating electric field is immediately applied to the PEEK melt, which is still in a viscous flow state, through inner and outer electrodes to obtain the composite insulating layer. A thermally conductive interface layer is formed on the outer surface of the insulating layer by a mold. The outer conductive layer is stranded outside the composite insulating layer and is formed by stranding a second type of irregularly shaped conductor in the opposite direction to the inner conductive layer, with the stranding pitch increasing in an arithmetic sequence. The sheath layer is extruded outside the outer conductive layer, and multiple TiNi shape memory alloy wires are uniformly embedded in its interior along the axial direction.

[0010] Preferably, the composite nanoparticles account for 5%-15% of the total mass of the composite insulating layer; The preparation method of the composite nanoparticles is as follows: Nano-BaTiO3 powder is added to deionized water and dispersed thoroughly by ultrasonic or mechanical stirring to form a stable suspension; Under continuous stirring, aluminum salt solution was slowly added dropwise to the suspension, and the pH value of the system was precisely controlled at 8-9 with ammonia water; then centrifuged and repeatedly washed with deionized water and ethanol to remove unreacted ions; finally dried to obtain BaTiO3@Al2O3 core-shell nanoparticles. It was obtained by treating the surface of core-shell nanoparticles with γ-aminopropyltriethoxysilane coupling agent.

[0011] Preferably, the aluminum salt is aluminum sulfate or aluminum isopropoxide with a concentration of 0.5-3 mol / L.

[0012] Preferably, the frequency of the applied alternating electric field is 5-15 kHz.

[0013] Preferably, the insulating layer contains a thermo-reversible crosslinking agent. When the temperature of the insulating layer reaches 120℃-180℃, the thermo-reversible crosslinking agent undergoes a de-crosslinking-re-crosslinking reaction, repairing microcracks and localized breakdown channels inside the insulating layer.

[0014] Preferably, the thermo-induced reversible crosslinking agent is a furan-maleimide adduct based on the Diels-Alder reaction, with a mass fraction of 2%-8% of the total mass of the insulation layer.

[0015] This invention also discloses a manufacturing process for a high-strength cable, comprising the following steps: S1: Prepare the central load-bearing component; Fiber-reinforced resin matrix composites are pultruded into rods, and annular positioning grooves are machined on the surface of the rods by turning or molding, followed by surface roughening treatment. S2: Fabrication of the inner conductive layer; S2-1: Aluminum alloy or copper alloy billets are continuously extruded or drawn to form irregularly shaped conductors with protrusions and recesses. S2-2: A layered stranding process is adopted, in which multiple irregularly shaped conductors are stranded around the central load-bearing member in the first direction of rotation. The stranding pitch of each layer changes in a gradient along the radial direction. During stranding, a tension that decreases layer by layer is applied: the tension of the innermost layer is 80-120N, and the tension of the outermost layer is 30-60N. S3: Prepare the insulating layer; S3-1: After surface treatment with silane coupling agent, core-shell nanoparticles are mixed evenly with polyether ether ketone resin and thermo-induced reversible crosslinking agent in a high-speed mixer. S3-2: The mixture is melt-blended and granulated using a twin-screw extruder at an extrusion temperature of 340℃-380℃; S3-3: An extrusion process is used to coat the outer periphery of the inner conductive layer with insulating material. The thickness of the insulating layer is 1.0-3.0 mm, and a thermally conductive interface layer is formed on the outer surface of the insulating layer using a mold. S4: Fabrication of the outer conductive layer; Multiple irregularly shaped conductors are twisted around the outer circumference of the insulating layer in the second direction of rotation. The twisting pitch is determined by calculating the torque balance equation based on the torque response of the inner conductive layer. The tension applied during twisting is 70%-90% of the tension of the corresponding layer of the inner conductive layer. S5: Prepare the sheath layer; S5-1: After shape-setting heat treatment, the shape memory alloy wire is pre-stretched with a pre-stretch strain of 1%-5%. S5-2: Using a co-extrusion process, the pre-stretched shape memory alloy wire and the polymer matrix are co-extruded and coated on the outer periphery of the outer conductive layer, so that the shape memory alloy wire is embedded in the sheath layer in a wavy or spiral shape along the cable axis. S5-3: After extrusion, keep the cable under tension to cool and shape it, so that the sheath layer remains under the axial compressive prestress applied by the memory alloy wire after solidification; S6: Post-processing; The cable products undergo continuous vulcanization crosslinking or irradiation crosslinking treatment, followed by segmented cooling and winding.

[0016] The beneficial effects of this invention are: (1) This invention achieves zero torque response over a wide strain range by reverse twisting of the inner and outer conductive layers and accurately calculating the twisting pitch of the outer conductive layer based on the torque balance equation, so that the torque generated by the inner and outer conductive layers during axial tension cancels each other out. Unlike the simple reverse twisting of adjacent layers in the prior art, this invention achieves internal structural damage caused by torsional stress during cable tension through quantitative torque matching design, effectively solving the problem of internal structural damage caused by torsional stress during cable tension and significantly extending the torsional fatigue life of the cable. At the same time, the inner conductive layer adopts an asymmetric gradient twisting design, with the pitch of each layer changing radially and the twisting tension decreasing layer by layer, so that the stress transmission of each conductor tends to be synchronized, avoiding the layer-by-layer failure problem caused by the inner layer bearing the load first and the outer layer bearing the load later in the traditional twisting structure.

[0017] (2) This invention introduces a thermo-reversible crosslinking agent (furan-maleimide adduct) into the composite insulation layer. Utilizing the reversible nature of the Diels-Alder reaction, the insulation layer can actively repair internal microcracks and localized breakdown channels under high-temperature conditions. When the cable experiences a localized temperature rise of 120°C to 180°C due to overload or external heat sources, the crosslinking network undergoes a dynamic exchange of de-crosslinking and re-crosslinking, and the crack interface rebonds. This self-healing mechanism, synergistically with the excellent thermal stability of the PEEK matrix itself, significantly improves the long-term reliability and lifespan of the insulation layer under high-temperature conditions.

[0018] (3) In this invention, axially pre-stretched shape memory alloy wires are embedded in the sheath layer to apply initial axial compressive prestress to the sheath layer. When the cable is subjected to axial tension, the shape memory alloy wires generate elastic restoring force to compensate for the axial stress of the sheath layer, effectively delaying the fatigue accumulation damage of the sheath layer. More importantly, this invention sets a gradient structure thermally conductive interface layer in the insulation layer, which forms a synergistic effect with the shape memory alloy wires, enabling the heat generated by the insulation layer to be efficiently transferred to the shape memory alloy wires, triggering their thermally induced phase change recovery effect (Ni-Ti alloys generate superelasticity above the phase change temperature), further enhancing the stress compensation effect, and realizing the cross-layer functional coupling of thermal protection of the insulation layer and mechanical compensation of the sheath layer.

[0019] (4) This invention utilizes a triple mechanism of torque cancellation between the inner and outer conductive layers, high-temperature self-healing of the insulation layer, and axial stress compensation of the sheath layer to enable the cable to have adaptive adjustment capability under combined load conditions (simultaneously subjected to tensile, bending, torsional, and thermal loads), and its overall performance is significantly better than the simple superposition of each mechanism. From the conductive layer to the insulation layer and then to the sheath layer, a complete functional closed loop of "stress release-thermal damage repair-stress compensation" is formed, realizing the functional leap of the cable from passive load bearing to active response.

[0020] A thermally conductive interface layer is provided between the shape memory alloy wire and the insulating layer. The thermal conductivity of the thermally conductive interface layer is ≥2W / (m·K), which is used to transfer the heat generated by the insulating layer to the shape memory alloy wire and trigger the phase change recovery effect of the shape memory alloy wire. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the radial cross-sectional structure of the high-strength cable of the present invention.

[0022] 1-Central load-bearing component, 2-Inner conductive layer, 3-Composite insulating layer, 4-Outer conductive layer, 5-Sheath layer. Detailed Implementation

[0023] In a first aspect, the present invention provides a high-strength cable, comprising, from the inside out: a central load-bearing member 1, an inner conductive layer 2, a composite insulation layer 3, an outer conductive layer 4, and a sheath layer 5.

[0024] The central load-bearing component is a fiber-reinforced resin-based composite rod, and its surface is provided with annular positioning grooves at intervals along the axial direction to constrain the twisting position of the inner conductive layer.

[0025] The inner conductive layer is formed by stranding multiple irregularly shaped conductors around the central load-bearing member in an asymmetric gradient stranding manner. Each irregularly shaped conductor has mutually cooperating protrusions and recesses, with the protrusions and recesses of adjacent irregularly shaped conductors tightly fitted together. The stranding pitch of the inner conductive layer varies radially in a gradient (increasing): the inner layer pitch is 6-10 times the cable's outer diameter, and the outer layer pitch is 10-14 times the cable's outer diameter. The stranding direction of the inner conductive layer is the first helical direction.

[0026] The pitch of each layer satisfies the following relationship: P i = P 0 ·(1- k · i ),in P 0 The innermost pitch, i The layer number is the sequence number (increasing from the inside out). k The gradient coefficient ranges from 0.02 to 0.05. The stranding direction of the inner conductive layer is the first helical direction. A progressively decreasing tension is applied during stranding of each conductor layer: the tension of the innermost layer is 80-120N, and the tension of the outermost layer is 30-60N, to control the initial stress state of each conductor layer.

[0027] The insulating layer is a composite layer composed of a polyether ether ketone matrix and composite nanoparticles uniformly dispersed therein. A thermo-induced reversible crosslinking agent is dispersed within the insulating layer. When the temperature of the insulating layer reaches 120℃-180℃, the thermo-induced reversible crosslinking agent undergoes a de-crosslinking-re-crosslinking reaction, repairing microcracks and localized breakdown channels within the insulating layer.

[0028] The outer conductive layer is formed by twisting multiple irregularly shaped conductors around the outer periphery of the insulation layer. The twisting direction of the outer conductive layer is a second helix, which is opposite to the first helix. The twisting pitch of the outer conductive layer is determined by calculation based on the torque response of the inner conductive layer, so that the reverse torque generated by the outer conductive layer and the positive torque generated by the inner conductive layer are substantially canceled out when the cable is stretched axially. The irregularly shaped conductors of the outer conductive layer and the inner conductive layer have different cross-sectional shapes; the cross-sectional area of ​​the irregularly shaped conductors of the outer conductive layer is smaller than that of the irregularly shaped conductors of the inner conductive layer, and the cross-sectional shape is fan-shaped or Z-shaped to adapt to the curvature of the outer periphery of the insulation layer.

[0029] The sheath layer is composed of a polymer matrix and axially elastic shape memory alloy wires embedded therein. The shape memory alloy wires extend along the cable axis and are arranged in a wavy or spiral shape. During cable manufacturing, the shape memory alloy wires undergo pre-stretching treatment to apply initial axial compressive prestress to the sheath layer. When the cable is subjected to axial tension, the shape memory alloy wires generate elastic restoring force to compensate for the axial stress in the sheath layer. A thermally conductive interface layer is provided between the shape memory alloy wires and the insulation layer. The thermal conductivity of the thermally conductive interface layer is ≥2 W / (m·K), which is used to transfer the heat generated by the insulation layer to the shape memory alloy wires, triggering the phase change recovery effect of the shape memory alloy wires.

[0030] Furthermore, the stranding pitch of the outer conductive layer P out Determined based on the following torque balance equation: T in + T out =0; where T in and T out The torques generated by the inner and outer conductive layers under unit axial strain are respectively calculated using the stranding pitch, stranding angle, and cross-sectional modulus of the irregular conductor.

[0031] Furthermore, the thermo-induced reversible crosslinking agent is a furan-maleimide adduct based on the Diels-Alder reaction, with a mass fraction of 2%-8% of the total mass of the insulation layer.

[0032] Furthermore, the thermally conductive interface layer is composed of thermally conductive silicone grease or thermally conductive elastomer, with a thickness of 0.1-0.5 mm, and the shape memory alloy wire is made of Ni-Ti type shape memory alloy, with a phase transition temperature of 60℃-100℃ and a wire diameter of 0.2-1.0 mm.

[0033] Furthermore, the pre-tension strain of the memory alloy wire is 1%-5%, so that the sheath layer can withstand an axial compressive prestress of 0.5-2 MPa under no external load.

[0034] Secondly, the present invention provides a manufacturing process for the above-mentioned high-strength cable, comprising the following steps: S1: Prepare the central load-bearing component; Fiber-reinforced resin matrix composites are pultruded into rods, and annular positioning grooves are machined on the surface of the rods by turning or molding, followed by surface roughening treatment.

[0035] S2: Fabrication of the inner conductive layer; S2-1: An aluminum alloy or copper alloy billet is continuously extruded or drawn to form an irregularly shaped conductor with protrusions and recesses.

[0036] S2-2: A layered stranding process is adopted, in which multiple irregularly shaped conductors are stranded around the central load-bearing member in the first direction of rotation. The stranding pitch of each layer changes in a gradient along the radial direction. During stranding, a tension that decreases layer by layer is applied: the tension of the innermost layer is 80-120N, and the tension of the outermost layer is 30-60N.

[0037] S3: Prepare the insulating layer; S3-1: Mix the composite nanoparticles with polyetheretherketone resin and thermotropic reversible crosslinking agent in a high-speed mixer until homogeneous.

[0038] The preparation method of the composite nanoparticles is as follows: Nano-BaTiO3 powder is added to deionized water and dispersed thoroughly by ultrasonic or mechanical stirring to form a stable suspension; Under continuous stirring, aluminum salt solution was slowly added dropwise to the suspension, and the pH value of the system was precisely controlled at 8-9 with ammonia water; then centrifuged and repeatedly washed with deionized water and ethanol to remove unreacted ions; finally dried to obtain BaTiO3@Al2O3 core-shell nanoparticles. It was obtained by treating the surface of core-shell nanoparticles with γ-aminopropyltriethoxysilane coupling agent.

[0039] S3-2: The mixture is melt-blended and granulated using a twin-screw extruder at an extrusion temperature of 340℃-380℃.

[0040] S3-3: Using an extrusion process, the insulating layer material is coated on the outer periphery of the inner conductive layer. The thickness of the insulating layer is 1.0-3.0mm. Then, an alternating electric field is immediately applied to the PEEK melt, which is still in a viscous flow state, through the inner and outer electrodes to obtain a composite insulating layer. A thermally conductive interface layer is formed on the outer surface of the insulating layer through a mold.

[0041] S4: Fabrication of the outer conductive layer; Multiple irregularly shaped conductors are twisted around the outer periphery of the insulating layer in the second direction of rotation. The twisting pitch is determined by the torque balance equation based on the torque response of the inner conductive layer. The tension applied during twisting is 70% to 90% of the tension of the corresponding inner conductive layer.

[0042] S5: Prepare the sheath layer; S5-1: After the shape memory alloy wire undergoes heat treatment for shaping, it is subjected to pre-stretching treatment with a pre-stretching strain of 1%~5%.

[0043] S5-2: The pre-stretched shape memory alloy wire and the polymer matrix are co-extruded and coated on the outer periphery of the outer conductive layer using a co-extrusion process, so that the shape memory alloy wire is embedded in the sheath layer in a wavy or spiral shape along the cable axis.

[0044] S5-3: After extrusion, keep the cable under tension to cool and shape it, so that the sheath layer remains under the axial compressive prestress applied by the memory alloy wire after curing.

[0045] S6: Post-processing; The cable products undergo continuous vulcanization crosslinking or irradiation crosslinking treatment, followed by segmented cooling and winding.

[0046] Furthermore, in step S2-2, the stranding angle of each layer of irregularly shaped conductors is controlled according to the following relationship: tan αi = π D i / P i ,in αi Let be the twisting angle of the i-th layer. Di Let be the diameter of the nodal circle of the i-th layer, so that the axial strain response of each conductor layer tends to be consistent.

[0047] Furthermore, in step S4, the method for determining the stranding pitch of the outer conductive layer is as follows: a sample of the inner conductive layer is prepared, and its torque response curve is measured on a universal testing machine when it is stretched axially to a strain of 0.5%-2%; based on the measured torque response, the optimal stranding pitch of the outer conductive layer is determined by iterative calculation so that the torques of the inner and outer conductive layers cancel each other out within the target strain range.

[0048] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0049] Example 1 S1: Prepare the central load-bearing component; Fiber-reinforced resin matrix composite material is pultruded into rods with a diameter of 8 mm. Annular positioning grooves are machined on the surface of the rods by turning, with a groove depth of 0.5 mm, a groove width of 2 mm, and a spacing of 20 mm between adjacent grooves. Surface roughening treatment is then performed (sandblasting, roughness Ra≥3.2μm).

[0050] S2: Fabrication of the inner conductive layer; S2-1: Oxygen-free copper rods are continuously extruded to form a trapezoidal conductor with protrusions and recesses. The inner conductive layer consists of 4 layers, with the following number of conductors in each layer: 6 in layer 1, 11 in layer 2, 16 in layer 3, and 21 in layer 4, for a total cross-section of 400 mm².

[0051] S2-2: A layered stranding process is adopted, in which multiple irregularly shaped conductors are stranded around the central load-bearing component in a leftward direction. The stranding pitch of each layer is set as follows: Layer 1 pitch is 240mm (12 times the cable outer diameter), Layer 2 pitch is 224mm, Layer 3 pitch is 208mm, and Layer 4 pitch is 192mm (approximately 9.6 times the cable outer diameter), with a gradient coefficient k≈0.033. The stranding tension is set as follows: Layer 1 100N, Layer 2 80N, Layer 3 55N, and Layer 4 35N. During stranding, a guide wheel frame with a pre-torsion angle of 45° is set between each layer's distribution plate and the stranding die to counteract the angular deviation caused by the rotation of the stranding cage and prevent the formation of step defects.

[0052] S3: Prepare the insulating layer; S3-1: The preparation method of the composite nanoparticles is as follows: Nano-BaTiO3 powder is added to deionized water and dispersed thoroughly by ultrasonic or mechanical stirring to form a stable suspension; Under continuous stirring, an aluminum salt solution (1.5 mol / L aluminum sulfate solution) was slowly added dropwise to the suspension, and the pH value of the system was precisely controlled at 8-9 with ammonia water; then centrifuged and repeatedly washed with deionized water and ethanol to remove unreacted ions; finally dried to obtain BaTiO3@Al2O3 core-shell nanoparticles. The nanoparticles were treated with γ-aminopropyltriethoxysilane coupling agent. The amount of coupling agent was 2% of the mass of the core-shell nanoparticles. The nanoparticles were refluxed in ethanol solution at 80°C for 2 hours, dried and ground, and then mixed with PEEK resin (Victrex® 150XF, average particle size 25 μm) and furan-maleimide adduct DA crosslinking agent at a mass ratio of 94:4:2 in a high-speed mixer until homogeneous.

[0053] S3-2: The mixture is melt-blended and granulated using a twin-screw extruder. The extrusion temperature is 340℃ (feed section) → 360℃ (melting section) → 375℃ (die head), and the screw speed is 200 rpm.

[0054] S3-3: An extrusion process is used to coat the outer periphery of the inner conductive layer with insulating material. The insulating layer thickness is 2.0 mm, the extrusion temperature is 370℃, and the extrusion rate is 0.5 m / min. An annular thermally conductive groove is formed on the outer surface of the insulating layer using a die with annular protrusions. The groove depth is 0.3 mm, the width is 0.5 mm, and the pitch is 5 mm. Immediately afterwards, an alternating electric field is applied to the still viscous PEEK melt through inner and outer electrodes. The frequency of the applied alternating electric field is 5-15 kHz, thus obtaining a composite insulating layer. S4: Fabrication of the outer conductive layer; Multiple irregularly shaped conductors (with a fan-shaped cross-section, the cross-sectional area being 70% of that of a single conductor in the inner conductive layer) are twisted around the outer circumference of the insulation layer in a right-hand direction. The twist pitch is determined as follows: An inner conductive layer sample is prepared, and its torque response curve is measured on a universal testing machine when stretched axially to a strain of 0.5%-1.5%. Based on the measured torque response, the optimal outer conductive layer pitch is calculated to be 175 mm, ensuring that the torques of the inner and outer conductive layers cancel each other out within the target strain range. The twist tension is 80% of the tension of the corresponding inner conductive layer.

[0055] S5: Prepare the sheath layer; S5-1: Ni-Ti memory alloy wire (0.3 mm diameter, phase transformation temperature 65 ℃) is subjected to shaping heat treatment (500 ℃ × 30 min, rapid cooling) and then pre-stretched with a pre-stretch strain of 3%.

[0056] S5-2: Inject thermally conductive silicone grease (thermal conductivity 3.5W / (m·K), thickness 20μm) into the annular thermally conductive groove on the outer surface of the insulating layer, and then coat it with a thermally conductive silicone rubber encapsulation layer (thickness 0.2mm, alumina filler mass ratio 75%, thermal conductivity 2.5W / (m·K)) through a co-extrusion process.

[0057] S5-3: A co-extrusion process is used to co-extrude pre-stretched shape memory alloy wires and thermoplastic polyurethane (TPU) matrix onto the outer periphery of the thermally conductive interface layer, so that the shape memory alloy wires are spirally embedded in the sheath layer along the cable axis with a spiral pitch of 10mm. After extrusion, the cable is kept under 30N tension for cooling and shaping.

[0058] S6: Post-processing; The cable products are subjected to continuous vulcanization and crosslinking treatment at 180℃ for 8 hours, then cooled to room temperature in sections and wound up.

[0059] Example 2 The difference from Example 1 is that in this example, the central load-bearing component is a steel core, the twisting pitch gradient coefficient of each layer of the inner conductive layer is k=0.02, the mass fraction of DA crosslinking agent is 6%, the mass fraction of composite nanoparticles is 8%, and the thermally conductive interface layer is filled with boron nitride-filled thermally conductive polyurethane elastomer (filler mass ratio 80%, thermal conductivity 3.0W / (m·K)). The remaining process parameters are the same as in Example 1.

[0060] Comparative Example 1 The difference from the example is that the composite nanoparticles used are alumina obtained by treatment with γ-aminopropyltriethoxysilane coupling agent, and the other process parameters are the same as in Example 1.

[0061] Performance test data: Based on relevant standards, the cable obtained in Example 1 was subjected to performance tests, and the results are as follows: Table 1. Performance test results of samples from Example 1 and Comparative Example 1

[0062] Test results analysis: The tensile strength of the composite insulation layer reached 118 MPa. After heat treatment at 120℃, the breakdown field strength recovery rate reached 82%, proving that the high-temperature self-healing function of the DA reversible crosslinking agent was effectively utilized. The overall tensile strength of the cable reached 285 MPa; the bending fatigue life reached 58,000 cycles (6D bending radius); and the torsional fatigue life reached 12,500 cycles (±90° / m torsion). All of the above performances are superior to those of Comparative Example 1, proving that the technical characteristics of this embodiment have a synergistic effect.

[0063] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A high-strength cable, characterized in that, From the inside out, it includes: The central load-bearing component (1) is a carbon fiber composite core rod or a high-strength steel strand; The inner conductive layer (2) is twisted to the outside of the central load-bearing member and is formed by twisting a first type of irregular conductor in a variable pitch and variable compression ratio manner. The composite insulating layer (3) is wrapped around the outside of the inner conductive layer. It is made by extruding polyether ether ketone resin and composite nanoparticles after melt blending. Then, an alternating electric field is applied to the PEEK melt, which is still in a viscous flow state, through the inner and outer electrodes to obtain the composite insulating layer. A thermally conductive interface layer is formed on the outer surface of the insulating layer by a mold. The outer conductive layer (4) is stranded outside the composite insulating layer and is formed by stranding a second type of irregularly shaped conductor in the opposite direction to the inner conductive layer and in a manner in which the stranding pitch increases in an arithmetic sequence. The sheath layer (5) is extruded outside the outer conductive layer, and multiple TiNi shape memory alloy wires are uniformly embedded in its interior along the axial direction.

2. The high-strength cable according to claim 1, characterized in that, The composite nanoparticles account for 5%-15% of the total mass of the composite insulating layer; The preparation method of the composite nanoparticles is as follows: Nano-BaTiO3 powder is added to deionized water and dispersed thoroughly by ultrasonic or mechanical stirring to form a stable suspension; Under continuous stirring, aluminum salt solution was slowly added dropwise to the suspension, and the pH value of the system was precisely controlled at 8-9 with ammonia water; then centrifuged and repeatedly washed with deionized water and ethanol to remove unreacted ions; finally dried to obtain BaTiO3@Al2O3 core-shell nanoparticles. It was obtained by treating the surface of core-shell nanoparticles with γ-aminopropyltriethoxysilane coupling agent.

3. A high-strength cable according to claim 2, characterized in that, The aluminum salt is aluminum sulfate or aluminum isopropoxide with a concentration of 0.5-3 mol / L.

4. A high-strength cable according to claim 1, characterized in that, The frequency of the applied alternating electric field is 5-15 kHz.

5. A high-strength cable according to claim 1, characterized in that, The insulating layer contains a thermo-induced reversible crosslinking agent.

6. A high-strength cable according to claim 5, characterized in that, The thermo-induced reversible crosslinking agent is a furan-maleimide adduct, with a mass fraction of 2%-8% of the total mass of the insulation layer.

7. A manufacturing process for a high-strength cable, characterized in that, Includes the following steps: S1: Prepare the central load-bearing component; Fiber-reinforced resin matrix composites are pultruded into rods, and annular positioning grooves are machined on the surface of the rods by turning or molding, followed by surface roughening treatment. S2: Fabrication of the inner conductive layer; S2-1: Aluminum alloy or copper alloy billets are continuously extruded or drawn to form irregularly shaped conductors with protrusions and recesses. S2-2: A layered stranding process is adopted, in which multiple irregularly shaped conductors are stranded around the central load-bearing member in the first direction of rotation. The stranding pitch of each layer changes in a gradient along the radial direction. During stranding, a tension that decreases layer by layer is applied: the tension of the innermost layer is 80-120N, and the tension of the outermost layer is 30-60N. S3: Prepare the insulating layer; S3-1: Core-shell nanoparticles are surface-treated with silane coupling agent and then mixed evenly with polyether ether ketone resin and thermo-induced reversible crosslinking agent in a high-speed mixer. S3-2: The mixture is melt-blended and granulated using a twin-screw extruder at an extrusion temperature of 340℃-380℃; S3-3: An extrusion process is used to coat the outer periphery of the inner conductive layer with insulating material. The thickness of the insulating layer is 1.0-3.0 mm, and a thermally conductive interface layer is formed on the outer surface of the insulating layer using a mold. S4: Fabrication of the outer conductive layer; Multiple irregularly shaped conductors are twisted around the outer circumference of the insulating layer in the second direction of rotation. The twisting pitch is determined by calculating the torque balance equation based on the torque response of the inner conductive layer. The tension applied during twisting is 70%-90% of the tension of the corresponding layer of the inner conductive layer. S5: Prepare the sheath layer; S5-1: After shape-setting heat treatment, the shape memory alloy wire is pre-stretched with a pre-stretch strain of 1%-5%. S5-2: Using a co-extrusion process, the pre-stretched shape memory alloy wire and the polymer matrix are co-extruded and coated on the outer periphery of the outer conductive layer, so that the shape memory alloy wire is embedded in the sheath layer in a wavy or spiral shape along the cable axis. S5-3: After extrusion, keep the cable under tension to cool and shape it, so that the sheath layer remains under the axial compressive prestress applied by the memory alloy wire after solidification; S6: Post-processing; The cable products undergo continuous vulcanization crosslinking or irradiation crosslinking treatment, followed by segmented cooling and winding.

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