High-voltage cable and manufacturing method

Abstract

The invention relates to the field of high-voltage cable manufacturing, and provides a high-voltage cable and a manufacturing method thereof, and the manufacturing method comprises the steps: twisting a plurality of monofilaments, and wrapping the monofilaments with enameled wires to form fan-shaped conductor strand blocks; a plurality of fan-shaped conductor strand blocks are twisted to form a split conductor, and a semi-conductive water-blocking strapping layer is arranged on the outer side of the split conductor; a conductor shielding layer, a cross-linked polyethylene insulating layer and an insulating shielding layer are sequentially wrapped on the periphery of the semi-conductive water-blocking strapping layer; the outer side of the insulation shielding layer is wrapped with a semi-conductive buffer waterproof layer; a corrugated aluminum sleeve is arranged on the outer side of the semi-conductive buffer waterproof layer, and online cooling is carried out; the end of the finished corrugated aluminum sleeve is coated with a water-blocking filling layer; the outer sides of the corrugated aluminum sleeve and the water-blocking filling layer are coated with an anti-corrosion layer and a plastic protection layer to form a high-voltage cable semi-finished product; a drawing head is arranged at one end of the high-voltage cable semi-finished product. The product quality and the production efficiency are improved, manpower and material resources are saved, the use environment is expanded, and the safety of construction, installation and operation is improved.

Description

Technical Field

[0001] The present invention relates to the field of high-voltage cable manufacturing, and in particular to a high-voltage cable and a manufacturing method thereof. Background Art

[0002] With the rapid development of power grid transmission in recent years, the demand for high-voltage cables has also increased. In order to ensure the construction quality and efficiency of high-voltage cable products, it is necessary to continuously improve the cable structure and production process to facilitate the stable operation of the power grid and convenient construction, improve construction efficiency, and enhance cable transmission safety and service life.

[0003] When transmitting AC current, cable conductors are subject to skin effect and proximity effect, which reduces the effective cross-sectional area of ​​the conductor and increases the AC resistance, resulting in conductor loss and heat generation, and reduces the transmission capacity. This phenomenon increases with the increase of the conductor cross-section.

[0004] In the existing technology, direct welding is often used to repair cold welds and leaking welds in the production process of corrugated aluminum sheaths. However, the above repair method may cause potential quality problems such as burning and carbonization of the wrapping tape when the corrugated aluminum sheath is in close contact with the semi-conductive buffer layer, thereby causing failure of the buffer tape at the repaired location. In severe cases, the resistance may be abnormally high, resulting in cable burning, causing irreversible quality problems in actual cable operation. Summary of the Invention

[0005] The present invention provides a high-voltage cable and a manufacturing method thereof, which are used to solve the defects in the prior art of corrugated aluminum sheaths, such as burning and carbonization of the inner semi-conductive buffer layer and damage to the cross-linked core when repairing the cold solder joints and leaked solder joints during the production process, thereby causing the cable to break down during operation.

[0006] The present invention provides a method for manufacturing a high-voltage cable, comprising the steps of: S1. Twisting multiple monofilaments, pressing them into a fan-shaped die, and wrapping them with enameled wire on the outside to form a fan-shaped conductor strand block; S2. Twisting n sector-shaped conductor strands into a shape to form a split conductor, and providing a semi-conductive water-binding layer on the outer side of the split conductor; S3, wrapping the conductor shielding layer, the cross-linked polyethylene insulation layer, and the insulation shielding layer in sequence around the outer periphery of the semi-conductive resistance water bundling layer; S4, the outer side of the insulating shielding layer is wrapped with a semi-conductive buffer water-blocking layer; S5. Complete the corrugated aluminum sleeve on the outside of the semi-conductive buffer water-blocking layer and cool it online; S6. Coating a water-blocking filling layer on both ends of the completed corrugated aluminum sleeve; S7. An anti-corrosion layer and a plastic sheath are coated on the outer sides of the corrugated aluminum sheath and the water-blocking filling layer to form an outer sheath, thereby forming a semi-finished high-voltage cable; S8. Set a traction head at one end of the semi-finished high-voltage cable.

[0007] According to a method for manufacturing a high-voltage cable provided by the present invention, between step S7 and step S8, the method further includes: S7', connect the high-voltage cable semi-finished product and the traction head through the aluminum tube.

[0008] According to a high-voltage cable manufacturing method provided by the present invention, in step S1, the outermost monofilament of each sector-shaped conductor strand block is an enameled wire, and the enameled wire is arranged on the outermost layer of each sector-shaped conductor strand block and is twisted and pressed together with the inner layer bare copper wire.

[0009] According to a high-voltage cable manufacturing method provided by the present invention, in step S2, n sector-shaped conductor strands are twisted and formed with the center line of the circular strand at a set pre-twisted pitch through a strand cabling machine. During the twisting and cabling process, the twisting and cabling pitch is set to 2100mm-2300mm. After twisting and cabling, they are pressed and formed by multiple molds, and the distance between each mold is not greater than 0.5. The semi-conductive tape is wrapped around the wrapping machine using a seam process to fix it, completing the preparation of the split conductor, where n≥3.

[0010] According to a high-voltage cable manufacturing method provided by the present invention, in step S3, an extruder is used to simultaneously extrude a conductor shielding layer, a cross-linked polyethylene insulation layer and an insulation shielding layer outside a prepared split conductor, the moisture content of the cross-linked polyethylene material is ≤30ppm, and the extruded material is filtered before extrusion, the extrusion temperature of the conductor shielding layer and the insulation shielding layer is 90°C to 110°C from the fuselage to the die head, the melting temperature of the conductor shielding layer and the insulation shielding layer is 100°C to 110°C, the extrusion temperature of the cross-linked polyethylene insulation layer is 100°C to 115°C from the fuselage to the die head, the melting temperature of the cross-linked polyethylene insulation layer is 120°C to 130°C, and the temperature difference of the three-layer co-extruded melt is less than 1°C when it converges at the die mouth, and the pressure is greater than 100MPa.

[0011] According to a high-voltage cable manufacturing method provided by the present invention, in step S4, a seam-butting or overlapping wrapping process is adopted; in step S6, the water-blocking filling layer is coated in the range of 0m-2m at both ends of the corrugated aluminum sheath.

[0012] According to a high-voltage cable manufacturing method provided by the present invention, in step S5, a corrugated aluminum sheath production equipment is used to longitudinally wrap a layer of aluminum tape around the prepared semi-conductive buffer and water-blocking layer. During the longitudinal wrapping process, the aluminum tape is gradually wrapped into a cylindrical shape using 4-6 forming horn molds, and then the weld seal of the wrapped seams is completed by welding. When welding the seams of the aluminum tape, a pressure roller is added to the sizing die to roll the seams of the aluminum tape to ensure that the weld seams of the aluminum tapes are tightly and horizontally connected to avoid the problem of uneven weld seams. The welding current is controlled between 220A and 230A. During welding, a cooling section is provided within a range of 20mm-50mm from the position where the corrugated aluminum sleeve needs to be repaired.

[0013] According to a high-voltage cable manufacturing method provided by the present invention, in step S7, when the anti-corrosion layer is coated on the outside of the water-blocking filling layer, the anti-corrosion layer is made of asphalt, and the residence time in the asphalt tank does not exceed 20 seconds. The asphalt is applied by spraying, and the middle section without a water-blocking filling layer is coated with asphalt by immersion.

[0014] According to a method for manufacturing a high-voltage cable provided by the present invention, in step S7', the method includes: According to the size of the traction head, peel off the outer sheath of one end of the high-voltage cable semi-finished product, leaving the aluminum sheath of the cable body; The inner surface of one end of the aluminum tube equipped with the corrugated spiral section is evenly coated with sealant, and is then rotated and sleeved on the aluminum sleeve of the cable body in the direction of the cable spiral; Put the traction head onto the conductor and crimp it. The other end of the traction head is overlapped and welded to one end of the aluminum tube. Install the lifting ring on the traction head and tighten the locking screw. Apply fastening glue on the threads of the lifting ring and the locking screw. After the traction head cools down, apply water-blocking glue on the weld, wrap water-blocking tape around the welding point between the aluminum tube and the traction head, and the peeling point between the aluminum sheath of the cable body and the outer sheath, put on the heat shrink tube and heat it so that the heat shrink tube wraps and covers the traction head, and the overlapping length of the heat shrink tube and the aluminum sheath of the cable body is 100mm-200mm.

[0015] The present invention also provides a high-voltage cable, including a high-voltage cable manufactured by any of the above manufacturing methods.

[0016] The high-voltage cable and manufacturing method provided by the present invention are achieved by twisting multiple single filaments, pressing them into shape through a fan-shaped mold, and wrapping them with enameled wire on the outside. While effectively suppressing eddy current losses, the use of insulating paper is eliminated, the production efficiency of the strands is greatly improved, and the quality risk problem of broken insulating paper strips and disconnected strips during the production process is avoided.

[0017] The corrugated aluminum sheath is completed on the outside of the semi-conductive buffer water-blocking layer and cooled online, which solves the problem of burning and carbonizing the inner semi-conductive buffer layer and damaging the cross-linked wire core when repairing the cold solder joints and leaking solder joints during the production process of the corrugated aluminum sheath, which in turn leads to cable breakdown during cable operation.

[0018] A water-blocking filling layer is coated on the two ends of the completed corrugated aluminum sheath within a range of 0m-2m, which solves the construction problem that when the traditional asphalt coating method cannot prevent the cable from being immersed in water, water penetrates into the cable along the gap between the corrugated aluminum sheath and the outer sheath. This reduces cable waste, saves manpower and material resources, improves the safety of cable construction and installation, and expands the construction environment of high-voltage cables.

[0019] By connecting the high-voltage cable semi-finished product and the traction head through an aluminum tube, a high-quality connection between the corrugated aluminum sleeve and the traction head is achieved, the traction tension is improved, and quality problems such as excessive gaps in some areas, insufficient welding strength, cold welding, and excessive welding when welding the traction head and the corrugated aluminum sleeve are avoided. At the same time, welding time is saved and the overall production time of the traction head is shortened.

[0020] Therefore, the high-voltage cable and manufacturing method provided by the present invention improve product quality and production efficiency, save manpower and material resources, expand the use environment, improve the safety of construction, installation and operation, improve the production and manufacturing process of the high-voltage cable, and effectively ensure the realization of the high-voltage cable function. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a schematic flow chart of the high-voltage cable manufacturing method provided by the present invention.

[0023] Figure 2 It is a structural schematic diagram of the high-voltage cable provided by the present invention.

[0024] Figure 3 It is a schematic diagram of the installation structure of the traction head in the high-voltage cable provided by the present invention.

[0025] Figure 4 It is a structural schematic diagram of the welding auxiliary device in the high-voltage cable provided by the present invention.

[0026] Reference numerals: 100. Center line; 1. Split conductors; 2. Semiconducting water-blocking bundling layer; 3. Conductor shielding layer, cross-linked polyethylene insulation layer and insulation shielding layer; 4. Semiconducting buffer water-blocking layer; 5. Corrugated aluminum sheath; 6. Water-blocking filling layer; 7. Anti-corrosion layer; 8. Plastic sheath; 9. Traction head; 10. Aluminum tube; 11. Cable body aluminum sheath; 12. Conductor; 13. Heat shrink tubing; 14. High-temperature wrapping tape; 15. Thermometer; 16. Cooling thermal conductive silicone tube; 17. Cooling water supply system. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] The following combination Figure 1 and Figure 2 The method for manufacturing a high-voltage cable of the present invention comprises the following steps: S1. Twist multiple single wires together, press them into shape through a fan-shaped die, and wrap them with enameled wire on the outside to form a fan-shaped conductor strand block.

[0029] S2. Twisting n sector-shaped conductor strands into a shape to form a split conductor 1, and providing a semi-conductive water-repellent bundling layer 2 on the outer side of the split conductor 1, where n≥3.

[0030] In the above step S2, the sector-shaped conductor strand block may be divided into four, five (may include a circular center line) or six (may include a circular center line), and then the conductor strand block is twisted and formed by a strand block cabling machine to form a segmented conductor 1.

[0031] In order to complete the above step S2, a design method for a split conductor is provided, which is as follows: According to the standard GB / T 3956, confirm the DC resistance of the design nominal cross section at 20°C, here 1600mm 2 Take the fifth segmentation as an example, 1600mm 2 The DC resistance of copper conductor at 20℃ is required to be no more than 0.0113Ω / km.

[0032] The first step is based on the formula: (1) Where k1 is the adjustment coefficient for metal resistance increment; k2 is the stranding coefficient for stranded conductors; k3 is the stranding coefficient for stranded cables; k1, k2, and k3 can be taken as 1.02 to 1.06 based on experience; ρ is the resistivity of copper conductor at 20°C, which is 0.017241Ω·mm 2 / m; R is the DC resistance of the copper conductor at 20℃, which is 0.0113Ω / km.

[0033] Substituting the above parameters into formula (1), we can get the actual cross-sectional area S of the conductor to be 1619.14 mm 2 ; The second step is to design and calculate the actual cross-sectional area S of a single fan-shaped strand. A and center line S B Assume that the actual area of ​​the center line S B 100mm 2 , then the actual area S of a single sector block is: (2) Calculation can be obtained S A 302.83mm 2 .

[0034] The third step is to design the diameter D of the split conductor and the centerline diameter D' of the circular compressed conductor. Where η is the filling factor, which is 0.88~0.91, and α is the cabling coefficient, which is 1.02~1.06.

[0035] Through calculation, it can be concluded that the conductor diameter D is designed to be 48.1mm; the centerline diameter D' of the circular compressed conductor is designed to be 11.9mm The fourth step is to design the conductor single wire diameter d: the number of single wires in a single fan-shaped strand and the number of center lines of the circular compressed conductor are designed using the n+6 structure, still based on 1600mm 2 For example, the monofilament structure design of a single fan-shaped strand block is 1+6+12+18+24; the center line structure of a circular compressed strand block is 1+6+12.

[0036] Diameter of single wire of fan-shaped strand d a and the diameter d of the monofilament at the center line of the circular strand b Calculation: The elongation δ is 9%~12% According to the above design formula, the design value of the single wire diameter da of the fan-shaped strand block is 2.64 mm, and the single wire diameter d of the center line of the circular strand block is 2.64 mm. bThe design value is 2.72mm; in order to unify the single wire specifications, the single wire diameter is designed to be the same as d, which is d a d b The average value of is as follows: Where: N is the design number of sector strands (5 for a five-segment strand). n1 is the number of individual strands in a sector strand, and n2 is the number of individual strands along the centerline of a circular strand. Calculation shows that the conductor's single-filament diameter, d, is 2.64 mm. The enameled wire's single-filament size should be appropriately enlarged based on actual calculations to meet the conductor resistance specification.

[0037] Through the above design method, the corresponding split conductor structure parameters can be obtained.

[0038] The semi-conductive water-resistant bundling layer 2 is composed of a composite of polyester fabric, a semi-conductive adhesive, and a high-speed expanding water-absorbing resin. The polyester fabric is required to have a breaking strength of 260 N / cm or more and an elongation at break of not less than 35%. The semi-conductive adhesive does not exceed 10% of the total content, and the high-speed expanding water-absorbing resin does not exceed 20% of the total content, and is evenly attached to the polyester fabric.

[0039] S3. Wrap the conductor shielding layer, the cross-linked polyethylene insulation layer and the insulation shielding layer 3 in sequence around the outer periphery of the semi-conductive resistance water-binding layer 2.

[0040] In step S3, three extruders are used to simultaneously extrude the conductor shielding layer, the cross-linked polyethylene insulation layer, and the insulation shielding layer outside the prepared multifunctional split conductor. The moisture content of the cross-linked polyethylene material is ≤30ppm to avoid the increase of cross-linking by-products. Each extruder head uses a seven-layer filter screen of 20 mesh / 60 mesh / 120 mesh / 300 mesh / 80 mesh / 40 mesh / 20 mesh to filter the extruded material. S4, the outer side of the insulating shielding layer is wrapped with a semi-conductive buffer water-blocking layer 4.

[0041] The semiconductive buffer water-blocking layer 4 is composed of a composite of nonwoven fabric, semiconductive material, and superabsorbent material. The melt index of the nonwoven fabric is 4-6 g / 10 min. The conductive carbon black in the semiconductive material has a DBP absorption value of ≥100 ml / 100 g. The carbon black is subjected to plasma surface activation treatment (power 6 kW, Ar gas protection environment). The superabsorbent material is required to have an expansion ratio of ≥400% (72 hours). The interface bonding of each layer is strengthened. An acrylic film is pre-applied to the surface of the semiconductive buffer water-blocking layer and electron beam irradiation (dose rate 10 kGy / s) induces a grafting reaction. The peel strength is ≥10 N / mm. The semiconductive buffer water-blocking layer 4 can be a single layer or multiple layers. Its breaking strength is not less than 40 N / cm, its elongation at break is not less than 15%, its pH is controlled at 7-8, its surface resistance is ≤400 Ω, and its volume resistivity is ≤2×104 Ω·cm. The semiconductive material content is not less than 30%, and the superabsorbent material content is not less than 20%.

[0042] S5. Complete the corrugated aluminum sleeve 5 on the outer side of the semi-conductive buffer water-blocking layer and cool it online.

[0043] In the above steps, the problem of the inner semi-conductive buffer layer being burned and carbonized and the cross-linked core being damaged during the production of the corrugated aluminum sleeve 5 and the cable being broken down during operation is solved.

[0044] Among them, the corrugated aluminum sleeve 5 is made of aluminum strip welded and corrugated. The chemical composition of the aluminum strip is Si≤0.25%, Fe≤0.35%, Cu≤0.05%, Mn≤0.03%, Mg≤0.03%, Zn≤0.05%, V≤0.05%, Ti≤0.03%, other (single impurity)≤0.03%, Al≥99.6%, the thickness of the aluminum strip is 1.5mm~3.5mm, the tensile strength is 70MPa~100MPa, and the elongation is ≥20%.

[0045] S6. A water-blocking filling layer 6 is coated on the two ends of the completed corrugated aluminum sleeve 5 within a range of 0 m to 2 m.

[0046] The water-blocking filling layer 6 is an insulating-grade water-blocking adhesive or tape, which provides a water-blocking function between the corrugated aluminum sheath and the outer sheath. The main components of the water-blocking adhesive are organic silica gel and water-blocking particles, with the organic silica gel comprising no less than 70% of the total content and the water-blocking particles no less than 20% of the total content, and the remaining proportion no more than 10%. The moisture content is no more than 1%. The insulating water-blocking tape is composed of a composite of flat non-woven fabric, glue, and highly absorbent material, wherein the highly absorbent material and glue are mixed and attached to the non-woven fabric to form the insulating water-blocking tape. The insulating-grade water-blocking adhesive or tape is placed on the surface of the corrugated aluminum sheath at both ends of the high-voltage cable for a certain length, and has excellent water-blocking properties.

[0047] When the water-blocking filling layer 6 is made of water-blocking glue, the water-blocking glue is coated and then heated, dried, and solidified on the surface of the corrugated aluminum sleeve 5 , with a thickness controlled to be 1 mm to 2 mm.

[0048] S7. An anti-corrosion layer 7 and a plastic sheath 8 are coated on the outside of the corrugated aluminum sheath 5 and the water-blocking filling layer 6 to form an outer sheath, thereby forming a semi-finished high-voltage cable.

[0049] Among them, the anti-corrosion layer 7 is a special asphalt for cables, which requires its needle penetration (25℃, 5s, 100g) ≥35 1 / 10mm, adhesion rate (0℃) ≥95%, solubility (trichloroethylene) ≥99.0%, flash point (open) ≥260℃, and softening point 85℃~100℃. The cable asphalt is mainly a high-performance special asphalt formed by mixing montmorillonite and asphalt matrix, which has enhanced isolation effect and asphalt bonding properties. Montmorillonite and asphalt modifier are stirred in 100℃ water at a ratio of 7:3 for 7h~8h, and then molten asphalt with a temperature of 190℃~220℃ is directly added. At the same time, 10 parts of epoxy resin, 2 parts of antioxidant, and 15 parts of calcium stearate are added and stirred for 6h~10h to obtain special asphalt for cables.

[0050] The plastic sheath 8 is composed of polyvinyl chloride resin, plasticizer, calcium zinc composite stabilizer, lubricant, filler, impact modifier, flame retardant and other processing aids, among which, the polyvinyl chloride resin is 100 parts, the plasticizer is 30 to 60 parts of dioctyl phthalate, the stabilizer is 7 to 11 parts, the lubricant is 2 to 3 parts of calcium stearate and paraffin composite, the filler is 90 to 122 parts of nano calcined kaolin, the impact modifier is 10 to 25 parts of methyl methacrylate-butadiene-styrene copolymer, and the flame retardant is 30 to 45 parts of antimony trioxide and aluminum hydroxide.

[0051] Among them, the plastic sheath 8 can adopt a special semi-rigid PVC sheath, which effectively shortens the bulging caused by insufficient hardness of the sheath material during argon arc welding inflation, thereby ensuring the product quality of the high-voltage cable.

[0052] S8. Set a traction head 9 at one end of the high-voltage cable semi-finished product.

[0053] like Figure 3 As shown, in some feasible embodiments of the present invention, between step S7 and step S8, the following is further included: S7 ′, connecting the high-voltage cable semi-finished product and the traction head 9 through the aluminum tube 10 .

[0054] In some feasible embodiments of the present invention, in step S1, the outermost monofilament of each sector-shaped conductor strand block is an enameled wire, and the enameled wire is arranged at the outermost layer of each sector-shaped conductor strand block and is twisted and pressed together with the inner bare copper wire.

[0055] In some feasible embodiments of the present invention, in step S2, n sector-shaped conductor strands are twisted and formed with the center line of the circular strand at a set pre-twisted pitch through a strand cabling machine. During the twisting and cabling process, the twisting and cabling pitch is set to 2100mm-2300mm. After twisting and cabling, they are pressed and formed by multiple molds, and the distance between each mold is not more than 0.5. They are then fixed by wrapping with a semi-conductive tape using a seam-seaming process using a wrapping machine to complete the preparation of the split conductor 1.

[0056] In the above steps, a large horizontal cabling machine can be used, and the horizontal cabling machine has at least six pay-off frames. The center lines of the sector-shaped conductor strand blocks and the circular strand blocks are placed on the corresponding pay-off frames respectively to achieve cabling of multiple sector-shaped strand blocks.

[0057] In some feasible embodiments of the present invention, in step S3, an extruder is used to simultaneously extrude the conductor shielding layer, the cross-linked polyethylene insulation layer and the insulation shielding layer 3 outside the prepared divided conductor, the moisture content of the cross-linked polyethylene material is ≤30ppm, and the extruded material is filtered before extrusion, the extrusion temperature of the conductor shielding layer and the insulation shielding layer is 90℃~110℃ from the fuselage to the head, the melting temperature of the conductor shielding layer and the insulation shielding layer is 100℃~110℃, the extrusion temperature of the cross-linked polyethylene insulation layer is 100℃~115℃ from the body to the head, the melting temperature of the cross-linked polyethylene insulation layer is 120℃~130℃, and the temperature difference of the three-layer co-extruded melt is <1℃ when it converges at the die, and the pressure is >100MPa.

[0058] The above steps promote the mutual diffusion of molecular chains. After the three-layer co-extrusion of the conductor shield, XLPE insulation, and insulation shield is completed, it directly enters a sealed multi-section pipeline. The first section of the pipeline uses a nitrogen forced cooling device to quickly cool the extruded conductor shield, XLPE insulation, and insulation shield layers and solidify them on the multifunctional split conductor. The forced cooling temperature is controlled at 60°C to 80°C to prevent sagging and the resulting extruded layer from failing. Then, under the protection of 12 Bar to 15 Bar nitrogen pressure and the action of 180°C to 350°C high temperature, where the nitrogen purity is ≥99.999% and the oxygen content is less than 20ppm, to prevent oxidative embrittlement. The XLPE insulation layer completes the chemical cross-linking process and is then cooled and formed using nitrogen or water, completing the preparation of the three-layer co-extrusion of the conductor shield, XLPE insulation, and insulation shield.

[0059] In some feasible embodiments of the present invention, in step S4, a wrapping machine is used to sequentially wrap the semi-conductive buffer water-blocking layer around the prepared conductor shielding + cross-linked polyethylene insulation + insulation shielding three-layer co-extrusion layer, and a butt-seam or overlapping wrapping process can be used.

[0060] In some feasible embodiments of the present invention, in step S5, a corrugated aluminum sheath production device is used to longitudinally wrap a layer of corrugated aluminum sheath, i.e., an aluminum strip, around the prepared semi-conductive buffer and water-blocking layer. During the longitudinal wrapping process, the aluminum strip is gradually wrapped into a cylindrical shape using 4-6 forming horn molds, and then the weld seal of the wrapped seams is completed by welding. When welding the seams of the aluminum strips, a pressure roller is added to the sizing die to roll the seams of the aluminum strips to ensure that the weld seams of the aluminum strips are tightly and horizontally butted, avoiding the problem of uneven weld seams. The welding current is controlled between 220A and 230A. In the above steps, spiral corrugation is performed on the surface of the aluminum sleeve by a linked corrugating machine, the corrugation pitch is controlled between 40 mm and 50 mm, and the corrugation depth is controlled between 5 mm and 10 mm. Here, requirement 1 is that the distance between the forming trumpet-shaped dies is between 100 mm and 300 mm. The distance between each forming trumpet-shaped die is based on the end close to the sizing die, and the spacing is set in a ratio of 1:1:2:2. The corresponding forming trumpet-shaped die sizes are: the first die is based on the outer diameter of the semi-conductive buffer water-blocking layer plus (5 mm to 10 mm), the second die is based on the outer diameter of the semi-conductive buffer water-blocking layer plus (20 mm to 50 mm), the third die is based on the outer diameter of the semi-conductive buffer water-blocking layer plus (50 mm to 100 mm), the fourth die is based on the outer diameter of the semi-conductive buffer water-blocking layer plus (100 mm to 150 mm), and the last two dies are based on the outer diameter of the semi-conductive buffer water-blocking layer plus (150 mm to 180 mm).

[0061] like Figure 4 As shown, in order to better solve the problem of repairing cold welds and leaking welds during the welding process, a welding auxiliary cooling device is proposed, which includes a cooling water supply system 17, a cooling thermal conductive silicone tube 16, a thermometer 15 and a high-temperature wrapping tape 14. The cooling water supply system 17 is connected to the cooling thermal conductive silicone tube 16 to form a cooling circuit; the cooling thermal conductive silicone tube 16 is wrapped around both sides of the welding point at a distance of 1 cm to 2 cm; a thermometer 15 is provided under the cooling thermal conductive silicone tube 16 for temperature monitoring; an insulating high-temperature wrapping tape 14 is provided under the thermometer 15; the high-temperature wrapping tape 14 is provided on the surface of the corrugated aluminum sleeve 5 for high-temperature protection.

[0062] During the repair welding, a cooling section is set within a range of 20mm-50mm from the position where the corrugated aluminum sleeve 5 needs to be repaired through the welding auxiliary cooling device. First, a wrapping method is adopted to wrap one or more layers of high-temperature wrapping tape at a distance of 1cm~2cm at both ends of the welding point. The thickness of the wrapping tape is between 0.2m~0.5mm, and then 1~2 layers of cooling heat-conducting silicone tube 16 are wrapped on the wrapping tape. The cooling heat-conducting silicone tube 16 is made of silicone base material + graphene and ceramic heat-conducting particles. It has a tubular structure and is connected to cooling circulating water at both ends. The cooling circulating water is treated by a chiller to ensure that the cooling water ripple is within 0℃~10℃. When welding, an argon arc welding machine is used and special welding materials are selected. Zinc-aluminum alloy wire, zinc content is 0.25%~0.35%, welding current is set at 190A~220A, spot welding is adopted, each spot welding time is 3s~5s, and welding is completed in a "three long, one short, one rest" cycle. "Three long, one short, one rest" means continuous spot welding for 3 times and then continuous short spot welding for 1 time, the continuous short spot welding time is 5s-8s, and then the welding is paused for 30s-40s. After the display value of thermometer 15 is lower than the room temperature, the "three long, one short, one rest" operation is repeated until the welding work is completed.

[0063] After the production of the corrugated aluminum sleeve 5 is completed, one of the ends is sealed with a lead seal, and the other end is sealed with a metal sealing sleeve with a lead seal and an air nozzle. The cable is then inflated with a special inflation tool. The gas is nitrogen with a purity of not less than 99.999%, the air pressure is not less than 0.5MPa, the inflation time is not less than 2h, the pressure holding time is 12h~16h, and the air pressure deviation during this period is ±0.15MPa. The welding sealing of the corrugated aluminum sleeve 5 is tested.

[0064] In some feasible embodiments of the present invention, in step S7, when the anti-corrosion layer 7 is applied to the outside of the water-blocking filling layer 6, the anti-corrosion layer 7 is made of asphalt, and the residence time in the asphalt tank does not exceed 20 seconds. The asphalt is applied by spraying, and the middle section without a water-blocking filling layer is coated with asphalt by immersion. The extrusion temperature is set according to different materials, ranging from 120°C to 180°C from the fuselage to the head. The appropriate temperature is selected according to the material. After the plastic sheath is extruded, it directly enters the first section of the cooling water tank. The temperature of the first section is controlled at 20°C to 25°C. After the initial fixation and forming in the first section of the water tank, it enters the second section of the water tank. The temperature of the second section is controlled below 20°C. After secondary cooling, it enters the multi-drive retractable integrated storage disk to complete the preparation of the plastic sheath.

[0065] In addition, the preparation of the aluminum tube 10 is completed during the preparation process of the corrugated aluminum sleeve 5. The welded aluminum tube is produced in the manner of step S5 to produce a 15 cm to 20 cm long aluminum tube. The outer diameter of the aluminum tube is 2 mm to 3 mm greater than the outer diameter of the corrugated aluminum sleeve produced in step 5. The corrugation depth and pitch are the same as those in step 5. One-third of the length of one end of the aluminum tube is a flat aluminum sleeve, and the remaining two-thirds of the length of the other end is a corrugated aluminum sleeve. The preparation of the aluminum sleeve connecting device is completed, and its tensile strength is not less than 1.2 times the tensile strength of the cable.

[0066] In some feasible embodiments of the present invention, step S7' includes: Step 1: According to the size of the traction head 9, peel off the outer sheath at one end of the high-voltage cable semi-finished product. The stripping length is the traction head + (100-200) mm. Then clean the remaining asphalt and water-blocking glue, and the remaining cable body aluminum sheath 11.

[0067] Step 2: The inner surface of the end of the aluminum tube 10 equipped with the corrugated spiral section is evenly coated with sealant, and then rotated and sleeved on the aluminum sleeve 11 of the cable body in the direction of the cable spiral; Step 3: Put the traction head 9 onto the conductor 12 and crimp it. The other end of the traction head 9 overlaps and welds with one end of the aluminum tube 10.

[0068] The conductor 12 is used to connect the pulling head 9 and the split conductor 1 .

[0069] Step 4: Use a welding machine to weld the overlapping end of the traction head 9 and the aluminum tube 10 flat aluminum sleeve to complete the welding of the traction head 9 and the aluminum tube 10; at the other end, use the same welding method to weld the spiral end completed in the second step to the cable body aluminum sleeve 11 together, and control the welding current between 150A-200A.

[0070] Step 5: Install the lifting ring on the traction head 9 and tighten the locking screw. Apply fastening glue on the threads of the lifting ring and the locking screw.

[0071] Step 6: After the traction head 9 has cooled, apply water-blocking adhesive to the welds. Wrap water-blocking tape around the welds between the aluminum tube 10 and the traction head 9, and the separation between the cable body aluminum sheath 11 and the outer sheath. Apply heat shrink tubing 13 and heat until the tubing wraps around and covers the traction head 9, with the overlap between the tubing and the cable body aluminum sheath 11 being 100mm-200mm. One or more heat shrink tubing 13s can be used.

[0072] In summary, the manufacturing method of the high-voltage cable provided by the embodiment of the present invention is that the outermost layer of each fan-shaped conductor strand block is designed to be an environmentally friendly enameled wire, which is tightly pressed with the inner layer monofilament to form the required strand block. Multiple fan-shaped conductor strand blocks are used to complete the production of segmented conductors during cabling, thereby reducing the influence of the skin effect of large-section conductors; the risk of the corrugated aluminum sheath 5 damaging the internal structure by repair welding is solved through reasonable structural design and auxiliary rapid cooling device; by adding a water-blocking filling layer 6 within a certain length at both ends of the cable, the problem of water seepage between the aluminum sheath and the outer sheath due to damage to the end sheath is prevented; the outer sheath adopts a special semi-rigid polyvinyl chloride to increase the hardness of PVC, thereby solving the problem of bulging of the sheath due to insufficient hardness of PVC when the cable is inflated; the finished product also realizes the effective connection between the traction head 9 and the corrugated aluminum sheath 5 through a special connecting aluminum tube, thereby improving the production efficiency and the pulling force of the traction head. Through the above design of high-voltage cables, the production and construction quality and efficiency of high-voltage cables can be effectively improved, the use environment of high-voltage cables can be expanded, the production and manufacturing process of high-voltage cables can be improved, and the realization of the functions of high-voltage cables can be effectively guaranteed.

[0073] The high-voltage cable provided by the present invention is described below. The high-voltage cable described below and the manufacturing method of the high-voltage cable described above can be referred to each other.

[0074] The second aspect of the present invention provides a high-voltage cable, which comprises, from the inside to the outside, a center line 100, a multifunctional segmented conductor 1, a semi-conductive water-blocking bundling layer 2, a three-layer co-extruded layer 3 of conductor shielding + cross-linked polyethylene insulation + insulation shielding, a semi-conductive buffer water-blocking layer 4, a corrugated aluminum sheath 5, a water-blocking filling layer 6, an anti-corrosion layer 7, and a plastic sheath 8; a traction head 9, an aluminum tube 10, and a heat shrink tube 13 are provided at one end of the high-voltage cable. A semiconductive water-blocking binding layer 2 is provided outside the multifunctional segmented conductor 1, a three-layer co-extruded layer 3 of conductor shielding + cross-linked polyethylene insulation + insulation shielding is provided outside the semiconductive water-blocking binding layer 2, a semiconductive buffer water-blocking layer 4 is provided outside the three-layer co-extruded layer 3 of conductor shielding + cross-linked polyethylene insulation + insulation shielding, a corrugated aluminum sleeve 5 is provided outside the semiconductive buffer water-blocking layer 4, a water-blocking filling layer 6 is provided outside the corrugated aluminum sleeve 5, an anti-corrosion layer 7 and a plastic sheath 8 are provided outside the water-blocking filling layer 6, a traction head 9 is provided at one end of the high-voltage cable, the interior of the traction head 9 is connected and fixed to the multifunctional segmented conductor 1, an outer end of the traction head 9 is welded and fixed to the flat end of the aluminum tube 10, a spiral end of the aluminum tube 10 is connected to the corrugated aluminum sleeve 5 of the high-voltage cable end and is fixed by welding, and a heat shrink tube 13 is provided outside the traction head 9, the aluminum tube 10 and the corrugated aluminum sleeve 5 as a secondary protective layer.

[0075] The high-voltage cable provided by the present invention can achieve effective isolation of large-section divided conductor blocks of the high-voltage cable, solve the quality risk of unstable insulation of corrugated paper, and the corrugated aluminum sheath welding under rapid cooling more effectively protects the cross-linked wire core and the buffer layer from damage. The water-blocking glue filling layer between the corrugated aluminum sheath and the sheath at the cable end can effectively prevent the end from being damaged and water ingress; the use of semi-rigid PVC plastic sheath 8 can avoid bulging caused by insufficient hardness of the sheath material during argon arc welding inflation. At the same time, the use of special welding connecting pipes for high-voltage cable ends also improves the welding quality, enhances the construction tensile strength, and improves the production efficiency of the traction head.

[0076] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0077] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or modes and features of different embodiments or modes described in this specification without contradiction.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for manufacturing a high voltage cable, characterized in that: include: S1. Twisting multiple monofilaments, pressing them into a fan-shaped die, and wrapping them with enameled wire on the outside to form a fan-shaped conductor strand block; S2, twisting n sector-shaped conductor strands into a shape to form a split conductor (1), and providing a semi-conductive water-binding layer (2) on the outer side of the split conductor (1); S3, wrapping the conductor shielding layer, the cross-linked polyethylene insulation layer and the insulation shielding layer (3) in sequence around the outer periphery of the semi-conductive resistance water-binding layer (2); S4, a semi-conductive buffer water-blocking layer (4) wrapped around the outer side of the insulating shielding layer; S5, completing the corrugated aluminum sleeve (5) on the outer side of the semi-conductive buffer water-blocking layer and cooling it online; S6. Coating a water-blocking filling layer (6) on both ends of the completed corrugated aluminum sleeve (5); S7, coating the outer sides of the corrugated aluminum sheath (5) and the water-blocking filling layer (6) with an anti-corrosion layer (7) and a plastic sheath (8) to form an outer sheath, thereby forming a semi-finished high-voltage cable; S8. A traction head (9) is provided at one end of the semi-finished high-voltage cable.

2. The method for manufacturing a high-voltage cable according to claim 1, wherein: Between step S7 and step S8, the method further includes: S7', connect the high-voltage cable semi-finished product and the traction head (9) through the aluminum tube (10).

3. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S1 , the outermost layer of the monofilament of each sector-shaped conductor strand block is made of enameled wire, and the enameled wire is arranged at the outermost layer of each sector-shaped conductor strand block and is twisted and pressed together with the inner layer bare copper wire.

4. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S2, n sector-shaped conductor strands are twisted and formed with the center line of the circular strands at a set pre-twisted pitch through a strand cabling machine. During the twisting and cabling process, the twisting and cabling pitch is set to 2100mm-2300mm. After being twisted and cabled, they are pressed and formed by multiple molds, with the distance between each mold being no more than 0.

5. The semi-conductive tape is then wrapped and fixed by a wrapping machine using a seam process to complete the preparation of the split conductor (1), wherein n≥3.

5. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S3, an extruder is used to simultaneously extrude the conductor shielding layer, the cross-linked polyethylene insulation layer and the insulation shielding layer (3) outside the prepared split conductor. The moisture content of the cross-linked polyethylene material is ≤30ppm, and the extruded material is filtered before extrusion. The extrusion temperature of the conductor shielding layer and the insulation shielding layer is 90℃~110℃ from the machine body to the machine head, and the melting temperature of the conductor shielding layer and the insulation shielding layer is 100℃~110℃. The extrusion temperature of the cross-linked polyethylene insulation layer is 100℃~115℃ from the machine body to the machine head, and the melting temperature of the cross-linked polyethylene insulation layer is 120℃~130℃. When the three-layer co-extruded melt converges at the die, the temperature difference is less than 1℃ and the pressure is greater than 100MPa.

6. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S4, a seam-butting or overlapping wrapping process is adopted; in step S6, the water-blocking filling layer (6) is coated in a range of 0m-2m at both ends of the corrugated aluminum sleeve (5).

7. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S5, a corrugated aluminum sleeve production device is used to longitudinally wrap a layer of aluminum strip around the prepared semi-conductive buffer water-blocking layer (4). During the longitudinal wrapping process, the aluminum strip is gradually wrapped into a cylindrical shape using 4-6 forming horn molds, and then the welding seal of the wrapped seam is completed by welding. When welding the seams of the aluminum strips, a pressure roller is added to the sizing die to roll the seams of the aluminum strips to ensure that the welds of the aluminum strips are tightly and horizontally butted, avoiding the problem of uneven welds. The welding current is controlled between 220A and 230A. During welding, a cooling section is provided within a range of 20 mm to 50 mm from the position where the corrugated aluminum sleeve (5) needs to be repaired.

8. The method for manufacturing a high-voltage cable according to claim 1, wherein: In step S7, when the anti-corrosion layer (7) is coated on the outside of the water-blocking filling layer (6), the anti-corrosion layer (7) is made of asphalt, and the residence time in the asphalt tank does not exceed 20 seconds. The asphalt is applied by spraying, and the middle section without the water-blocking filling layer (6) is coated with asphalt by immersion.

9. The method for manufacturing a high-voltage cable according to claim 2, wherein: In step S7', it includes: According to the size of the traction head (9), the outer sheath of one end of the high-voltage cable semi-finished product is stripped off, and the aluminum sheath (11) of the cable body remains; The inner surface of one end of the aluminum tube (10) equipped with the corrugated spiral section is evenly coated with sealant, and the aluminum tube (10) is rotated and sleeved on the cable body aluminum sleeve (11) in the direction of the cable spiral; The traction head (9) is put on the conductor (12) and crimped, and the other end of the traction head (9) is overlapped and welded with one end of the aluminum tube (10); Install the lifting ring on the traction head (9), tighten the locking screw, and apply fastening glue on the threads of the lifting ring and the locking screw; After the traction head (9) cools down, apply water-blocking glue on the weld, wrap water-blocking tape around the welding point between the aluminum tube (10) and the traction head (9) and the peeling point between the cable body aluminum sleeve (11) and the outer sheath, and put on the heat shrink tube (13) and heat it so that the heat shrink tube (13) wraps around and covers the traction head (9), and the overlapping length between the heat shrink tube (13) and the cable body aluminum sleeve (11) is 100 mm to 200 mm.

10. A high voltage cable, characterized in that: The high-voltage cable is manufactured using the high-voltage cable manufacturing method according to any one of claims 1 to 9.

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