Super-tough wear-resistant aluminum alloy power cable and preparation process thereof

Abstract

The invention discloses preparation of a super-tough wear-resistant aluminum alloy power cable, and belongs to the technical field of medium-voltage and high-voltage power cables. The cable comprises a molded wire aluminum alloy conductor, a cable semi-conductive conductor shielding layer, an insulating layer, a semi-conductive insulating shielding layer and a metal shielding layer are nested outside the molded wire aluminum alloy conductor to form a main body part of the cable, an environment-friendly flame-retardant filling layer is further filled in the middle of the cable, a halogen-free low-smoke flame-retardant wrapping tape is arranged outside the cable, and a halogen-free low-smoke flame-retardant isolation sleeve is further arranged outside the wrapping tape; the toughness of an aluminum alloy conductor is optimized through a gradient annealing process, a tough PE and POE composite sheath material and a halogen-free flame-retardant synergistic formula are adopted, a multi-layer composite structure is designed, and the problems that an existing aluminum alloy cable is insufficient in toughness, a sheath is prone to cracking and electromagnetic loss is high are solved; the comprehensive performance of the cable is obviously better than that of similar copper cables and common aluminum alloy cables, and the cable is suitable for new energy power generation and power transmission scenes under complex working conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of medium and high voltage power cables, and in particular relates to a super-tough and wear-resistant aluminum alloy power cable. Background Art

[0002] At present, the structure of a general cable mainly includes a conductor, an insulating layer, a shielding layer and a protective layer; a Chinese invention patent with the authorization announcement number CN222106292U discloses a "new type of wear-resistant and corrosion-resistant aluminum alloy cable with reliable connection", which is firmly connected and applied in the field of aluminum alloy cables, including an insulating sleeve with a shielding layer fixed inside the insulating sleeve, and two support frames are sleeved on the surface of the insulating sleeve, and a plurality of rolling balls are arranged on the surface to avoid friction damage to the corrosion-resistant coating; the support frame is connected and fixed by setting fixing bolts to increase stability, and a support frame on the surface of the aluminum alloy cable can be reused after the cable is installed and the next cable is installed, which greatly improves the recycling rate; although the invention improves stability and recycling rate, the cable of the invention has limited performance in terms of corrosion resistance, strength, bending resistance, tensile strength, etc.

[0003] In order to solve the performance problems of cable corrosion resistance, strength, bending resistance, tensile strength, etc., the invention patent with authorization announcement number CN222071592U discloses a "corrosion-resistant aluminum alloy core low-voltage power cable", which includes a cable core, which is provided with conductor shielding, cross-linked polyethylene insulation, insulation shielding and metal shielding from the inside to the outside, the number of cable cores is 3-6, and a central metal reinforcement core is provided in the middle position, and a polytetrafluoroethylene wrapping tape is provided on the outside, which is filled with corrosion-resistant sealant; although the corrosion resistance, strength, bending resistance, tensile strength and other performances of the invention have been greatly improved, the toughness of the conductor is still insufficient, and environmental stress cracking is prone to occur during long-term use, and high electromagnetic loss leads to performance imbalance.

[0004] In summary, existing cables have the following disadvantages: 1) The aluminum alloy cable conductor has insufficient toughness. Due to its work hardening, it is brittle. The temperature and time of the traditional annealing process are single and it is difficult to control the balance between tensile strength and elongation at break. It is easy to crack after dynamic bending. 2) The sheath is prone to cracking. The polyethylene sheath material has high crystallinity and large internal stress, and the risk of cracking increases significantly, especially under low temperature or repeated bending conditions; 3) The electromagnetic loss is high, and the ordinary metal shielding layer generates eddy current loss due to electromagnetic induction, which reduces the transmission efficiency. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art and propose an ultra-tough and wear-resistant aluminum alloy power cable, which can solve the problems of insufficient toughness of the existing aluminum alloy cable conductor, easy cracking of the sheath and high electromagnetic loss.

[0006] To achieve the above-mentioned purpose, the present invention proposes an ultra-tough and wear-resistant aluminum alloy power cable, comprising a plurality of main bodies, an environmentally friendly flame-retardant filling layer and a protective sheath, wherein the main bodies are, from the inside to the outside, respectively, a profile aluminum alloy conductor, a semi-conductive conductor shielding layer, an insulating layer, a semi-conductive insulating shielding layer, and a metal shielding layer; the middle of the plurality of main bodies is filled with an environmentally friendly flame-retardant filling layer, and the cable main bodies and the environmentally friendly flame-retardant filling layer are combined together to form a cable core; a protective sheath is arranged on the outside of the cable core, and the protective sheath is, from the inside to the outside, respectively, a halogen-free low-smoke flame-retardant tape, a halogen-free low-smoke flame-retardant isolation sheath, a metal armor protective layer, and a halogen-free low-smoke flame-retardant outer sheath.

[0007] Preferably, the cable is modified by rare earth microalloying, and lanthanum La element is added to the aluminum alloy to form LaAl3 dispersed phase, which inhibits dislocation slip and improves flexibility.

[0008] Preferably, the cable adopts a low-temperature two-stage extrusion process to reduce the crystallinity of the material, eliminate internal stress, and extend the environmental stress cracking time to 500 hours.

[0009] Preferably, the cable has a multi-layer composite structure design, in which the conductor shielding layer is optimized and the semi-conductive shielding layer is made of graphene and ethylene-vinyl acetate copolymer composite material to improve interface smoothness and reduce the risk of local discharge.

[0010] Preferably, the environmentally friendly flame-retardant filling system uses ceramic silicone rubber as the filling rope, which works synergistically with the wrapping layer to achieve a flame-retardant grade of A.

[0011] Beneficial effects of the present invention: 1) Performance improvement: Due to the use of a composite sheath including PE and POE, a blend of linear low-density polyethylene and polyolefin elastomer, in which nano-silicon dioxide is added as a toughening agent, the sheath's elongation at break is greatly improved, the sheath's resistance to environmental stress cracking is improved by 10 times, and there is no cracking under low-temperature impact; 2) High efficiency and energy saving: The metal armor adopts a non-magnetic stainless steel belt spiral wrapping structure, which reduces the eddy current loss caused by the magnetic armor design, improves the transmission efficiency, and the cable weight is lighter than the copper cable, reducing the installation cost; 3) Improved environmental protection and safety: Due to the use of halogen-free flame retardant synergistic formula, environmentally friendly, low-smoke, halogen-free flame retardant materials such as ceramic fibers are selected to ensure the integrity and flame retardant properties of the cable. No toxic gas is released during combustion, and ultraviolet absorbers and antioxidants are added to improve the weather resistance and service life of the outer sheath. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the present invention; In the figure: A-type wire aluminum alloy conductor; B-semi-conductive conductor shielding layer; C-insulating layer; D-semi-conductive insulating shielding layer; E-metal shielding layer; F-environmentally friendly flame retardant filling layer; G-halogen-free low-smoke flame retardant tape; H-halogen-free low-smoke flame retardant isolation sleeve; I-metal armor protective layer; J-halogen-free low-smoke flame retardant outer sheath. DETAILED DESCRIPTION

[0013] Embodiment 1: See also Figure 1 The present invention is an ultra-tough and wear-resistant aluminum alloy power cable, comprising at least three main bodies, an environmentally friendly flame-retardant filling layer F and a protective sleeve, wherein the main bodies are, from the inside to the outside, respectively, a profile aluminum alloy conductor A, a semi-conductive conductor shielding layer B, an insulating layer C, a semi-conductive insulating shielding layer D, and a metal shielding layer E; the middle of at least three main bodies is filled with an environmentally friendly flame-retardant filling layer F, and the cable main body and the environmentally friendly flame-retardant filling layer F together constitute a cable core; a protective sleeve is arranged on the outside of the cable core, and the protective sleeve is, from the inside to the outside, respectively, a halogen-free low-smoke flame-retardant tape G, a halogen-free low-smoke flame-retardant isolation sleeve H, a metal armor protective layer I, and a halogen-free low-smoke flame-retardant outer sheath J.

[0014] Preparation of conductor and shielding layer: The aluminum alloy conductor of the profiled wire adopts a gradient annealing process, with a pre-annealing temperature of 350 degrees for 30 minutes, medium temperature softening at 400 degrees for 2 hours, nitrogen cooling to room temperature, and tensile strength controlled at 110MPa; the conductor is wrapped with a semi-conductive conductor shielding layer with a thickness of 1mm, and the material is a composite of graphene and ethylene-vinyl acetate copolymer; the insulating layer is cross-linked polyethylene with a thickness of 10.5mm, surrounded by a semi-conductive insulating shielding layer, and the structure is the same as the conductor shielding layer.

[0015] Metal shielding and filling: The metal shielding layer is made of copper tape with a thickness of 0.1mm, a width of 50mm, and an overlap rate of 30%. The three cable bodies are filled with an environmentally friendly flame-retardant filling layer made of ceramic silicone rubber with a diameter of 2mm. It works synergistically with the halogen-free, low-smoke flame-retardant tape to make the cable flame retardant grade reach Class A. The halogen-free, low-smoke flame-retardant tape is a polyester fiber tape with a thickness of 0.25mm.

[0016] Sheath and armor: The halogen-free low-smoke flame-retardant isolation sleeve is made of EVA with a thickness of 2.0mm; the metal armor protective layer is a galvanized steel belt with a thickness of 0.8mm, a width of 60mm, and spiral wrapping; the halogen-free low-smoke flame-retardant outer sheath is a PE and POE composite material with nano-silicon dioxide added, with a thickness of 4.4mm, and is formed by a low-temperature two-stage extrusion process to reduce crystallinity and eliminate internal stress. The environmental stress cracking time is up to 500 hours.

[0017] In this embodiment, after testing, the conductor's elongation at break is increased to 30%, the tensile strength is 120 MPa, and the bending life is equivalent to that of copper cable; the sheath has no cracks under low-temperature impact of -40°C, the oxygen index is 38%, and the smoke density test has a light transmittance of 80%, meeting environmental protection and flame retardant requirements; the bonding strength between the filling layer and the sheath interface is 3.5 N / mm, avoiding the risk of delamination.

[0018] A preparation process of an ultra-tough and wear-resistant aluminum alloy power cable comprises the following steps: a) Conductor processing: Use aluminum alloy conductor A, twist the aluminum alloy wires to form a multi-stranded conductor. During the twisting process, ensure the tightness and flexibility of the conductor. The cross-sectional area of ​​the conductor is designed according to the current carrying capacity requirements of the cable; b) Preparation of shielding layer and insulating layer: Extruding a semi-conductive conductor shielding layer B outside the aluminum alloy conductor A, using a special semi-conductive material, evenly extruding it on the conductor surface through an extruder to ensure close fit between the shielding layer and the conductor, and controlling the thickness within a specific range; c) Preparation of insulating layer and semi-conductive insulating shielding layer: Extruding insulating layer C and semi-conductive insulating shielding layer D outside semi-conductive conductor shielding layer B, controlling the thickness and uniformity of the insulating layer and shielding layer; d) Preparation of metal shielding layer: Wrap the metal shielding layer E around the semi-conductive insulating shielding layer D, using metal wire or metal tape for wrapping, and ensure the flatness and tightness of the metal wire or metal tape during wrapping; e) Cable core assembly and filling: Arrange multiple main cables processed in the above steps into a cable, and fill them with an environmentally friendly flame-retardant filling layer F; f) Preparation of protective sheath: wrap the cable core with halogen-free low-smoke flame-retardant tape G, extrude halogen-free low-smoke flame-retardant isolation sheath H, wrap the metal armor protective layer I, and extrude halogen-free low-smoke flame-retardant outer sheath J in sequence.

[0019] Embodiment 2: In this experiment, the conductor and shielding layer were prepared as follows: the aluminum alloy conductor of the profiled wire was subjected to a gradient annealing process, with a pre-annealing temperature of 360 degrees for 40 minutes, medium temperature softening at 410 degrees for 2.5 hours, and nitrogen cooling to room temperature. The tensile strength was controlled at 115 MPa; the conductor was wrapped with a semi-conductive conductor shielding layer with a thickness of 1.2 mm, and the material was a composite of graphene and ethylene-vinyl acetate copolymer; the insulating layer was cross-linked polyethylene with a thickness of 10.5 mm, surrounded by a semi-conductive insulating shielding layer with the same structure as the conductor shielding layer.

[0020] Metal shielding and filling: The metal shielding layer is made of copper tape with a thickness of 0.12mm, a width of 45mm, and an overlap rate of 35% for wrapping; the four cable bodies are filled with an environmentally friendly flame retardant filling layer made of ceramic silicone rubber with a diameter of 2.5mm, which works synergistically with the halogen-free, low-smoke flame retardant tape to make the cable flame retardant grade reach Class A. The halogen-free, low-smoke flame retardant tape is a polyester fiber tape with a thickness of 0.25mm.

[0021] Sheath and armor: The halogen-free low-smoke flame-retardant isolation sleeve is made of EVA with a thickness of 1.2mm; the metal armor protective layer is a galvanized steel strip with a thickness of 0.8mm, a width of 60mm, and spiral wrapping; the halogen-free low-smoke flame-retardant outer sheath is a PE and POE composite material with 2 parts of nano-silicon dioxide added, a thickness of 4.5mm, and is formed using a low-temperature two-stage extrusion process to reduce crystallinity, eliminate internal stress, and the environmental stress cracking time is up to 500 hours.

[0022] In this embodiment, after testing, the conductor's elongation at break is increased to 32%, the tensile strength is 125 MPa, and the bending life is equivalent to that of copper cable; the sheath has no cracks under low-temperature impact of -40 degrees, the oxygen index is 39%, and the smoke density test has a light transmittance of 77%, meeting environmental protection and flame retardant requirements; the bonding strength between the filling layer and the sheath interface is 3.6 N / mm, avoiding the risk of delamination.

[0023] Embodiment 3: Preparation of conductor and shielding layer: The aluminum alloy conductor of the profiled wire adopts a gradient annealing process, with a pre-annealing temperature of 340 degrees for 20 minutes, medium temperature softening at 390 degrees for 1.5 hours, and nitrogen cooling to room temperature. The tensile strength is controlled at 105MPa; the conductor is wrapped with a semi-conductive conductor shielding layer with a thickness of 0.8mm, and the material is a composite of graphene and ethylene-vinyl acetate copolymer; the insulating layer is cross-linked polyethylene with a thickness of 10.5mm, surrounded by a semi-conductive insulating shielding layer, and the structure is the same as the conductor shielding layer.

[0024] Metal shielding and filling: The metal shielding layer is made of copper tape with a thickness of 0.11mm, a width of 40mm, and an overlap rate of 25% for wrapping; the three cable bodies are filled with an environmentally friendly flame retardant filling layer made of ceramic silicone rubber with a diameter of 1.5mm, which works synergistically with the halogen-free, low-smoke flame retardant tape to make the cable flame retardant grade reach Class A. The halogen-free, low-smoke flame retardant tape is a polyester fiber tape with a thickness of 0.25mm.

[0025] Sheath and armor: The halogen-free low-smoke flame-retardant isolation sleeve is made of EVA with a thickness of 1.8mm; the metal armor protective layer is a galvanized steel strip with a thickness of 0.8mm, a width of 65mm, and spiral wrapping; the halogen-free low-smoke flame-retardant outer sheath is a PE and POE composite material with 2 parts of nano-silicon dioxide added, a thickness of 4.6mm, and is formed using a low-temperature two-stage extrusion process to reduce crystallinity and eliminate internal stress. The environmental stress cracking time is up to 500 hours.

[0026] In this embodiment, after testing, the conductor's elongation at break is increased to 28%, the tensile strength is 115 MPa, and the bending life is equivalent to that of copper cable; the sheath has no cracks under low-temperature impact of -40 degrees, the oxygen index is 36%, and the smoke density test has a light transmittance of 75%, meeting environmental protection and flame retardant requirements; the bonding strength between the filling layer and the sheath interface is 3.2 N / mm, avoiding the risk of delamination.

[0027] Working principle: 1) Power transmission and conductor function: The core component of the cable, the aluminum alloy conductor, is made of multiple aluminum alloy wires twisted together and is responsible for efficient current conduction. The gradient annealing process is used to make the conductor strong and tough at the same time, reducing the power loss during the transmission process and ensuring stable power transmission. 2) Electric field balance and insulation protection: The conductor is wrapped with a semi-conductive conductor shielding layer, an insulating layer, and a semi-conductive insulating shielding layer in sequence; the semi-conductive shielding layer can eliminate the roughness of the conductor surface, balance the electric field distribution, and prevent the electric field concentration from causing aging and breakdown of the insulation layer; the insulation layer uses insulating materials such as cross-linked polyethylene to effectively isolate the conductor from the outside world and ensure safe transmission of electrical energy; 3) Electromagnetic shielding and interference protection: The metal shielding layer surrounds the insulating shielding layer and is made of good conductor materials such as copper tape. A continuous and tight metal layer is formed through a wrapping process. It can shield the electromagnetic field generated by the conductor, prevent electromagnetic interference leakage from affecting peripheral equipment and communication systems, and resist external electromagnetic interference to ensure stable and reliable power transmission. 4) Flame retardant and environmental protection: The environmentally friendly flame retardant filling layer is filled between multiple cable bodies, with ceramic silicone rubber as the filling rope. When exposed to high temperature, it will be ceramicized to form a solid ceramic shell, blocking oxygen and heat, and inhibiting the spread of fire; the halogen-free low-smoke flame retardant outer sheath uses halogen-free flame retardant materials such as magnesium hydroxide and aluminum hydroxide. When burning, it produces low smoke and no toxic gas, ensuring personnel safety and reducing fire losses; 5) Improved mechanical protection and durability: The metal armor protective layer is spirally wrapped with stainless steel tape to provide strong mechanical protection for the cable, resist damage such as external pressure and stretching, and at the same time have anti-corrosion properties to ensure long-term and stable operation of the cable in harsh environments.

[0028] All parts work together to ensure that the cable operates efficiently, stably and safely in power transmission, and can adapt to a variety of complex environments and high-demand power transmission scenarios.

[0029] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. A super-tough and wear-resistant aluminum alloy power cable, characterized in that: The cable comprises at least three main bodies, an environmentally friendly flame-retardant filling layer (F) and a protective sleeve, wherein the main bodies are, from the inside to the outside, respectively, a profiled aluminum alloy conductor (A), a semi-conductive conductor shielding layer (B), an insulating layer (C), a semi-conductive insulating shielding layer (D), and a metal shielding layer (E); the environmentally friendly flame-retardant filling layer (F) is filled in the middle of at least three main bodies, and the cable main body and the environmentally friendly flame-retardant filling layer (F) together constitute a cable core; a protective sleeve is arranged on the outside of the cable core, and the protective sleeve is, from the inside to the outside, respectively, a halogen-free low-smoke flame-retardant tape (G), a halogen-free low-smoke flame-retardant isolation sleeve (H), a metal armor protective layer (I) and a halogen-free low-smoke flame-retardant outer sheath (J).

2. The super-tough and wear-resistant aluminum alloy power cable according to claim 1, characterized in that: The semiconductive conductor shielding layer (B) is made of a graphene and ethylene-vinyl acetate copolymer composite material.

3. The super-tough and wear-resistant aluminum alloy power cable according to claim 1, characterized in that: The environmentally friendly flame-retardant filling layer (F) is made of ceramic silicone rubber.

4. The super-tough and wear-resistant aluminum alloy power cable according to claim 1, characterized in that: The metal armor protection layer (I) adopts a stainless steel belt spirally wrapped structure, and the stainless steel belt is wrapped on the cable core in a spiral form.

5. A super-tough and wear-resistant aluminum alloy power cable according to any one of claims 1 to 4, characterized in that: The thickness ratio of the insulating layer (C) to the semi-conductive conductor shielding layer (B) is 3 to 5:1, and the thickness ratio of the environmentally friendly flame-retardant filling layer (F) to the cable body is 1:1 to 3.

6. A process for preparing an ultra-tough and wear-resistant aluminum alloy power cable, characterized in that: The following steps are involved: a) Conductor processing: Use aluminum alloy conductor (A) and twist the aluminum alloy wires to form a multi-stranded conductor. During the twisting process, ensure the tightness and flexibility of the conductor. The cross-sectional area of ​​the conductor is designed according to the current carrying capacity requirements of the cable; b) Preparation of shielding layer and insulating layer: Extruding a semi-conductive conductor shielding layer (B) outside the aluminum alloy conductor (A) uses a special semi-conductive material and extruding it evenly on the conductor surface through an extruder to ensure that the shielding layer fits tightly with the conductor and the thickness is controlled within a specific range; c) Preparation of insulating layer and semi-conductive insulating shielding layer: Extruding an insulating layer (C) and a semi-conductive insulating shielding layer (D) outside the semi-conductive conductor shielding layer (B), and controlling the thickness and uniformity of the insulating layer and the shielding layer; d) Preparation of metal shielding layer: Wrap the metal shielding layer (E) outside the semi-conductive insulating shielding layer (D) with metal wire or metal tape, and ensure the flatness and tightness of the metal wire or metal tape during wrapping; e) Cable core assembly and filling: Arrange multiple main cables processed in the above steps into a cable, and fill them with an environmentally friendly flame-retardant filling layer (F); f) Preparation of protective sheath: wrap the cable core with halogen-free low-smoke flame-retardant tape (G), extrude halogen-free low-smoke flame-retardant isolation sheath (H), wrap with metal armor protective layer (I), and extrude halogen-free low-smoke flame-retardant outer sheath (J).

7. The process for preparing a super-tough and wear-resistant aluminum alloy power cable according to claim 6, characterized in that: The profiled aluminum alloy conductor (A) is subjected to a gradient annealing process, wherein the profiled aluminum alloy conductor (A) is subjected to pre-annealing at 200 degrees for 240 minutes, medium-temperature softening at 320 minutes for 660 minutes, and cooling and shaping under nitrogen protection at 150 degrees for 120 minutes, and lanthanum La is added to the aluminum alloy to form a LaAl3 dispersed phase.

8. The process for preparing a super-tough and wear-resistant aluminum alloy power cable according to claim 6, characterized in that: The environmentally friendly flame-retardant filling layer (F) is filled between a plurality of cable bodies, with ceramic silicone rubber as the filling rope.

9. The process for preparing a super-tough and wear-resistant aluminum alloy power cable according to claim 6, characterized in that: During the extrusion process of the halogen-free, low-smoke, flame-retardant outer sheath (J), UV absorbers and antioxidants are added.

10. A process for preparing a super-tough and wear-resistant aluminum alloy power cable according to any one of claims 6 to 9, characterized in that: The halogen-free, low-smoke, flame-retardant outer sheath (H) is a composite sheath of PE and POE, which is blended with linear low-density polyethylene and polyolefin elastomer, with nano-silicon dioxide added as a toughening agent, and adopts a low-temperature two-stage extrusion process.

Images