Manufacturing method of light cross interconnection grounding coaxial cable and cable

Abstract

The invention discloses a manufacturing method of a light cross interconnection grounding coaxial cable. The cable structurally comprises an inner conductor, an inner insulating layer, an outer conductor and an outer insulating layer, the structure of the inner conductor is formed by sequentially and tightly pressing multiple layers of conductors from inside to outside of a central circular copper monofilament; the cross section of the central circular copper monofilament is circular; the cross sections of the other layers of conductors are annular, and each layer of conductor is formed by twisting special-shaped copper monofilaments with fan-ring-shaped cross sections; for the conductor on the same layer, the sector ring of the section of the monofilament is a part of the annular section of the conductor. The structure of the outer conductor is formed by sequentially compressing a plurality of layers of conductors from inside to outside; the cross section of each layer of conductor is annular, and each layer of conductor is formed by twisting special-shaped copper monofilaments with sector-ring-shaped cross sections; for the conductor on the same layer, the sector ring of the monofilament cross section is a part of the annular cross section of the conductor. The manufacturing method of the cable comprises the following steps: 1) manufacturing the inner conductor; 2) wrapping an inner insulating layer outside the inner conductor; 3) manufacturing an outer conductor outside the insulated wire core; and 4) manufacturing an outer insulating layer.

Description

Technical Field

[0001] The invention belongs to the technical field of cable manufacturing, and in particular relates to a manufacturing method of a light cross-interconnected grounded coaxial cable and a cable. Background Art

[0002] In 110kV and 220kV high-voltage power systems, induced voltage will be generated on the cable metal sheath or shielding layer when the cable line is operating normally or when the power frequency is short-circuited. In order to limit these overvoltages, the cable metal sheath often adopts single-point grounding, mid-point grounding, two-end grounding, cross-connection and other grounding methods. According to the "Technical Regulations for the Design of Urban Power Cable Lines", 10kV medium-voltage cross-linked polyethylene insulated power cables are usually selected as grounding protection.

[0003] Different from the coaxial cable used for signal transmission, the inner and outer conductors of the cross-connected grounded coaxial cable in the high-voltage power system are used to transmit electrical energy, such as:

[0004] The "A coaxial cable for cross-interconnection and grounding of ultra-high voltage cable lines" with publication number CN102254615A has a structure including an inner conductor located in the center, an inner conductor insulation layer extruded outside the inner conductor, an outer conductor sparsely wound outside the inner conductor insulation layer, and an outer conductor insulation layer extruded outside the outer conductor; the "High-voltage cable cross-interconnection and grounding connection coaxial cable" with publication number CN210925586U has a structure including an inner conductor, an inner semi-conductive shielding layer, an outer semi-conductive shielding layer, a buffer layer, an outer conductor group, a non-woven fabric winding layer and an outer sheath arranged in sequence from the inside to the outside, the outer conductor group including a plurality of outer conductors coaxial with the inner conductor and arranged in a ring; a plurality of outer conductors are arranged in a ring and a plurality of ring-shaped outer conductors are coaxially arranged with the inner conductor; etc.

[0005] The earliest starting point of the research on these cables was to merge the original two grounding wires into one, which reduced the possibility of misconnection, and the volume was reduced after the merger, which was simple, easy to manage and transport, and cost-saving. It was based on the function of the coaxial cable itself. There are also shielding layers added to the structure of the coaxial cable, such as the inner and outer semi-conductive shielding layers in the CN210925586U scheme, and the insulating screen layer and metal shielding layer that have recently appeared in the. These structural designs make the suspension potential too high, which is easy to cause the outer sheath to break down.

[0006] Moreover, during the use of existing coaxial cables, the sheaths are cross-connected and grounded during the laying and installation of cable lines. Hidden errors in certain contacts are prone to occur during the cross-connection wiring, resulting in incomplete transposition and difficulty in timely detection and correction, which increases the circulating current in the sheath. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention discloses a method for manufacturing a light cross-interconnected grounded coaxial cable and the cable.

[0008] A light cross-interconnect grounded coaxial cable comprises an inner conductor, an inner insulating layer, an outer conductor and an outer insulating layer extruded outside the outer conductor;

[0009] The inner conductor is composed of twisted copper monofilaments; an insulating material is wrapped around the inner conductor to form an inner insulating layer; an outer conductor with the same cross-section as the inner conductor is coaxially wound around the inner insulating layer; the outer conductor is composed of twisted copper monofilaments with special cross-sections; an insulating material is wrapped around the outer conductor to form an outer insulating layer;

[0010] The structure of the inner conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside outside the central circular copper monofilament; the cross section of the central circular copper monofilament is circular; the cross sections of the other layers of conductors are annular, and each layer of conductors is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the annular cross section of the conductor;

[0011] The structure of the outer conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside; the cross section of each layer of conductor is annular, and each layer of conductor is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the ring cross section of the conductor;

[0012] In the inner and outer conductors, the twisting directions of adjacent layers are opposite, and the twisting direction of the outermost layer is S direction.

[0013] Furthermore, there is a non-metallic tape wrapping layer between the inner insulating layer and the outer conductor; there is also a non-metallic tape wrapping layer between the outer conductor and the outer insulating layer.

[0014] The cross-sectional shapes of the shaped copper monofilaments constituting the conductors of the same layer are the same.

[0015] Compared with the conductors made of round monofilaments (through compact twisting and other process structures) by traditional processes, the surface smoothness of the conductors made by this method using special-shaped monofilaments with a specific structure is greatly improved without substantially increasing or changing the production equipment and production process. In production practice, it is found that even if there are slight defects on the surface of the special-shaped conductor structure, it does not affect the overall electrical performance requirements of the cable.

[0016] Compared with CN102254615A, the inner and outer conductor structures of this case are both made of twisted shaped single wires. The conductor surface is smooth, round, and has no protrusions, which reduces the discharge phenomenon at the tip of the conductor surface and homogenizes the electric field distribution. The conductor is compactly pressed into shape, the structure is stable, the conductor resistivity is reduced, and the conductive performance is improved.

[0017] Compared with CN210925586U, in addition to the above conductor structure, the shielding layer is also omitted. Thanks to the fact that the inner and outer conductor structures are made of special-shaped conductors pressed tightly, the inner insulating layer is flat and smooth, making the electric field more balanced, the insulating shielding layer structure can be omitted, and the floating potential can be avoided from being too high.

[0018] When the cable is used, the cross-connected grounded coaxial cable of the present invention is used to connect the protection box and the transposition box of the sheath insulation protection device of the 110kV-220kV cross-linked cable line. The inner conductor and its concentric outer conductor exist in a single cable at the same time, and the two are isolated from each other by the insulating layer. When used, the metal sheath and outer sheath of the same-phase high-voltage cable are respectively connected to avoid the invisible error of connecting the wrong phase, thereby ensuring the success of the cross-connection.

[0019] The manufacturing method of the above cable comprises the steps of:

[0020] 1) Manufacture inner conductor for spare use;

[0021] 2) wrapping the inner conductor obtained in step 1) with an inner insulating layer to obtain an insulated wire core;

[0022] 3) In step 2), an outer conductor structure wrapped around an insulated wire core is prepared, the steps comprising:

[0023] 3.1) Manufacturing non-metallic wrapping layer;

[0024] 3.2) manufacturing an outer conductor layer;

[0025] 3.3) Manufacturing non-metallic wrapping layer;

[0026] 4) wrapping the outer insulating layer outside the outer conductor layer prepared in step 3);

[0027] Specifically:

[0028] In the step 1):

[0029] 1.1) Make round copper monofilament for standby use:

[0030] Take a copper rod with a diameter of Φ8mm and draw it into a copper single wire with a diameter of Φ2.8~3.41mm. The tolerance of the copper single wire is required to be ±0.01mm, the elongation of the copper single wire is ≥35%, and the resistivity of the copper single wire does not exceed 0.017241Ω·mm 2 / m;

[0031] 1.2) Making inner and outer shaped copper monofilaments

[0032] Take a copper rod with a diameter of Φ8mm and draw special-shaped copper monofilaments with different fan-shaped cross-sections through a fan-shaped wire drawing die according to the specifications. The center angle of the special-shaped monofilament corresponding to each layer of fan ring is calculated according to the number of special-shaped monofilaments designed;

[0033] 1.3) Twisting of special-shaped single-filament conductors

[0034] The copper monofilaments are twisted in layers using a twisting machine.

[0035] For example, according to the arrangement of 1+6+10+14 (from the inner layer to the outer layer, there are 1, 6, 10 and 14 monofilaments in turn), divided into four layers and pressed three times, each layer is pressed and distributed in turn: 6 reels, 10 reels and 14 reels; for small-sized cable conductors, it can also be arranged in a 1+6 or 1+6+12 structure. The monofilament twist direction is set from the inside to the outside according to S, Z, S, the second outer layer monofilament twist direction is Z, and the outermost layer monofilament twist direction is S; the outermost layer monofilament twist pitch ratio does not exceed 15 times (s and z represent the twist direction of the stranded wire, s represents left direction, z represents right direction, left direction is counterclockwise, right direction is clockwise);

[0036] The requirements for the inner conductor are: the DC resistance of the conductor at 20°C meets the requirements of GB / T3956 standard; the outer diameter of the conductor is controlled to be 12.8-23.3 mm.

[0037] In the step 2):

[0038] The insulated wire core is made of high-electrical thermoplastic elastomer insulation material, and the insulation color can be natural color.

[0039] The extrusion process parameters are set as follows:

[0040] The inner insulation layer is extruded by a Φ90 extruder. Along the direction from feed to discharge, the temperatures of the 1st to 6th temperature zones of the extruder are 175±5℃, 180±5℃, 185±5℃, 185±5℃, 190±5℃ and 195±5℃ respectively, and the screw speed of the extruder is 20.0 rpm.

[0041] An extrusion die is used, and the die size is selected according to the outer diameter D1 of the conductor. The die core is generally d1 = D1 + (2-3) mm, and the die sleeve is generally d2 = d1 + (2 + K) × nominal thickness of the insulation layer. K is generally 1.2, which is calculated by the design of the average electric field strength that the cable insulation is subjected to. The average thickness of the inner insulation layer is not less than the nominal thickness.

[0042] The average speed of the production line is 15-18m / min;

[0043] The internal insulation extrusion process must pass the power frequency spark withstand voltage test, the test voltage is: 25kV.

[0044] In the step 3):

[0045] 3.1) Manufacturing of non-metallic wrapping layer

[0046] In order to ensure the stable contact performance of the outer conductor and reduce the risk of tip discharge, a non-metallic wrapping layer is used outside the wire core. For example, a layer of 0.12×60 semi-conductive nylon tape is overlapped and wrapped, and the minimum overlap rate is not less than 20%.

[0047] 3.2) Manufacturing the outer conductor layer

[0048] The specifications of the outer conductor are consistent with those of the inner conductor. A copper rod with a diameter of Φ8mm is used to draw special-shaped copper monofilaments with different fan ring cross-sections through a fan-shaped wire drawing die according to the specifications. The center angle of the special-shaped monofilaments corresponding to each layer of fan ring is calculated based on the number of special-shaped monofilaments designed. The cross-section of the outer conductor after twisting is equivalent to the conductor cross-section, and the DC resistance of the conductor at 20°C meets the requirements of GB / T3956 standard;

[0049] 3.3) Manufacturing of non-metallic wrapping layer

[0050] A non-metallic wrapping layer is used outside the outer conductor layer, for example, a layer of 0.12×60 semi-conductive nylon tape is wrapped over and over again, with a minimum overlap rate of not less than 20%, so that the outer conductor layer is not easy to loosen and the risk of tip discharge is reduced.

[0051] In the step 4):

[0052] The finished cable is made of high-electricity thermoplastic elastomer insulation material, and CABOT carbon black is added to the material at a ratio of 1-2%. The outer insulation color is black. The nominal thickness of the outer insulation layer is generally equal to that of the inner insulation, and the average thickness of the outer insulation is not less than the nominal thickness.

[0053] The extrusion process parameters are set as follows:

[0054] The outer insulation layer is extruded by a Φ120 extruder. Along the direction from feed to discharge, the temperatures of the 1st to 8th temperature zones of the extruder are 165±5℃, 170±5℃, 175±5℃, 180±5℃, 185±5℃, 190±5℃, 190±5℃ and 195±5℃, respectively. The screw speed of the extruder is 25.0 rpm.

[0055] An extrusion die is used, and the die size is selected based on the outer diameter D2 of the previous process. The die core is generally d3 = D2 + (2-3) mm, and the die sleeve is generally d4 = d3 + (2 + K) × nominal insulation thickness, where K is generally 1.2.

[0056] The average speed of the production line is 12-15 m / min;

[0057] The external insulation extrusion process must pass the power frequency spark withstand voltage test, the test voltage is: 25kV.

[0058] Although the existing silane cross-linked insulating material (such as the model YJG-3 product of Anhui Bost New Materials Co., Ltd.) can meet the functions and most performances of the cable, the cost is high and some performances cannot be met. Therefore, in order to meet the requirements of cable usage scenarios and reduce material costs while meeting the various performance requirements of the cable, the present invention also proposes a special high-electricity thermoplastic elastomer insulating material, and its formula system is shown in Table 1:

[0059] Table 1 Insulation material consists of the following raw materials in parts by weight

[0060] Serial number Material Name Mass parts / parts 1 SEBS 30～50 2 Polypropylene 20～40 3 White oil 8～20 4 Antioxidants 0.5～1.5 5 Lubricants 0.8～1.5 6 Silicone Masterbatch 3～5

[0061] In this material, polypropylene and the elastomer material SEBS (Styrene Ethylene Butylene Styrene, a linear triblock copolymer composed of polystyrene as the terminal segment and ethylene-butene copolymer obtained by hydrogenating polybutadiene as the middle elastic block) have good electrical properties. SEBS improves the extrusion processing performance of the material by oil filling. Polypropylene has excellent electrical properties at room temperature and high temperature conditions, and its dielectric loss and dielectric constant are both low. In addition, the above materials have good compatibility. After blending, extrusion and granulation, the material has excellent comprehensive performance.

[0062] The formula in Table 1 is suitable for the inner insulation layer. Compared with the inner insulation layer, the outer insulation layer has higher requirements in terms of wear resistance and other properties. Therefore, 1-2% of CABOT carbon black is added to the total mass of the raw materials of the inner insulation layer based on Table 1 as the formula of the insulation material used for the outer insulation layer.

[0063] In order to improve the performance of the cable and avoid the phenomenon of insufficient performance or redundant performance caused by directly using the existing cable insulation materials with similar functions, the present invention designs a new cable material and formulates a processing technology in combination with the cable structure characteristics.

[0064] The cable manufactured by the manufacturing method meets the various performance requirements of the light cross-interconnected grounded coaxial cable and also meets the requirements of mechanical properties, insulation properties, etc. under the use conditions. The method realizes the manufacturing of light cross-interconnected grounded coaxial cables with high quality, low cost and high performance.

[0065] The beneficial effects of the present invention are:

[0066] 1. When in use, one end of the cross-connected grounded coaxial cable can be connected to the metal sheath of the high-voltage power cable, and the other end can be connected to the grounding protection device. The overvoltage at the metal sheath end of the high-voltage power cable can be introduced into the grounding protection device, thereby effectively protecting the normal operation of the high-voltage power cable. The connection method of the inner and outer conductors is reasonable and convenient, and the use is reliable. It is used for the cross-connected wiring of high-voltage cables, which can effectively reduce the induced potential of the metal sheath.

[0067] 2. When a ground fault occurs in a cable line, the short-circuit current can flow back to the neutral point of the system, playing a shunting role. The return current offsets the impact of the magnetic field formed by most of the fault current on the adjacent communication and signal cables, and also has a certain shielding effect.

[0068] 3. The inner and outer conductors adopt a special-shaped single-filament twisted structure, and a specific preparation method is used to ensure the smooth surface of the conductor from both the structural and processing aspects, so that the electric field distribution on the conductor surface is more uniform. Avoid burrs from causing tip discharge and improve product performance. At the same time, the structure is simplified, and the conductor shielding layer structure is omitted on the basis of the special-shaped single-filament twisted structure, further reducing the cost of the cable, which is more than 5% lower than the cost of traditional coaxial cables.

[0069] If the conductor surface is smooth, the discharge at the tip of the conductor can generally be detected through a partial discharge test. If the conductor surface is uneven and has obvious protrusions, a concentrated cable area will be formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 Schematic diagram of the cable structure of this embodiment;

[0071] Figure 2 Schematic diagram of the structure inside the conductor of the cable of this embodiment;

[0072] Figure 2-1 This is a schematic diagram of the cross section of the outermost layer (14 single wires) of the inner conductor's shaped copper single wire. Figure 2-2 This is a schematic cross-sectional view of the sub-outer layer (10 single wires) of the inner conductor's shaped copper single wire. Figure 2-3 This is a schematic cross-sectional view of the shaped copper wires of the inner conductor's secondary inner layer (6 wires). Figure 2-4 This is a cross-sectional diagram of a circular copper monofilament in the center. The length unit is mm and the area unit is mm. 2 ;

[0073] Figure 3 Schematic diagram of the outer conductor structure of the cable in this embodiment;

[0074] Figure 3-1 This is a schematic diagram of the cross section of the outermost layer (30 single wires) of the outer conductor's shaped copper single wire. Figure 3-2 This is a cross-sectional diagram of the outer conductor's sub-outer layer (24 single wires) of shaped copper single wires. The length unit in the figure is mm and the area unit is mm. 2 ;

[0075] Figure 1 In: 1. Inner conductor, 2. Inner insulation layer, 3. Non-metallic tape wrapping layer (inner), 4. Outer conductor layer, 5. Non-metallic tape wrapping layer (outer), 6. Outer insulation layer. DETAILED DESCRIPTION

[0076] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0077] refer to Figure 1 to Figure 3 , a lightweight cross-interconnect grounded coaxial cable, comprising an inner conductor 1, an inner insulating layer 2, an outer conductor 4 and an outer insulating layer 6 extruded outside the outer conductor;

[0078] The inner conductor is composed of twisted copper monofilaments; an insulating material is wrapped around the inner conductor to form an inner insulating layer; an outer conductor with the same cross-section as the inner conductor is coaxially wound around the inner insulating layer; the outer conductor is composed of twisted copper monofilaments with special cross-sections; an insulating material is wrapped around the outer conductor to form an outer insulating layer;

[0079] The structure of the inner conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside outside the central circular copper monofilament; the cross section of the central circular copper monofilament is circular; the cross sections of the other layers of conductors are annular, and each layer of conductors is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the annular cross section of the conductor;

[0080] The structure of the outer conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside; the cross section of each layer of conductor is annular, and each layer of conductor is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the ring cross section of the conductor;

[0081] In the inner and outer conductors, the twisting directions of adjacent layers are opposite, and the twisting direction of the outermost layer is S direction.

[0082] There is a non-metallic tape wrapping layer (inner) 3 between the inner insulating layer and the outer conductor; there is also a non-metallic tape wrapping layer (outer) 5 between the outer conductor and the outer insulating layer.

[0083] The cross-sectional shapes of the shaped copper monofilaments constituting the conductors of the same layer are the same.

[0084] The method for manufacturing the lightweight cross-connected grounded coaxial cable comprises the following steps:

[0085] 1) Manufacturing inner conductor;

[0086] 2) wrapping the inner conductor obtained in step 1) with an inner insulating layer to obtain an insulated wire core;

[0087] 3) manufacturing an outer conductor outside the insulated wire core obtained in step 2), the steps comprising:

[0088] 3.1) Manufacturing non-metallic wrapping layer;

[0089] 3.2) manufacturing an outer conductor layer;

[0090] 3.3) Manufacturing non-metallic wrapping layer;

[0091] 4) Manufacturing the outer insulation layer;

[0092] The step 1) comprises:

[0093] 1.1) Making round copper monofilament:

[0094] Take the copper rod and draw it into a round copper monofilament of the required diameter. The tolerance requirement of the copper monofilament is ±0.01mm; the elongation of the copper monofilament is ≥35%, and the resistivity of the copper monofilament does not exceed 0.017241Ω·mm 2 / m;

[0095] 1.2) Making special-shaped copper monofilament:

[0096] Take the copper rod and draw the required fan-shaped copper monofilament with the required fan-shaped cross-section through the fan-shaped wire drawing die; for the same layer of shaped copper monofilaments, the central angle of the fan ring is calculated according to the number of shaped copper monofilaments; wire drawing must ensure that the corrugated arc angles of the shaped copper monofilaments in each layer are consistent;

[0097] 1.3) Shaped copper monofilament twisted:

[0098] The special-shaped copper monofilaments used in each layer are twisted in layers using a twisting machine. Each layer is pressed tightly after being twisted to ensure that there is no gap between the monofilaments after twisting, so that the conductor surface is smooth, the conductor resistivity is small after being pressed, and the conductivity is good;

[0099] The twist direction of the outermost layer of shaped copper monofilaments is S direction; the pitch diameter ratio of the outermost layer of monofilaments does not exceed 15 times;

[0100] The requirements for the inner conductor obtained through steps 1.1) to 1.3) are as follows: the DC resistance of the conductor at 20°C meets the requirements of GB / T3956 standard; the outer diameter of the inner conductor is controlled within the range of 12.8 to 23.3 mm;

[0101] In the step 2), a high-electricity thermoplastic elastomer insulation material is extruded outside the inner conductor to obtain an inner insulating layer, thereby obtaining an insulated wire core;

[0102] In the step 3):

[0103] Step 3.1) wrapping a layer of semi-conductive nylon tape around the insulated wire core to obtain a non-metallic wrapping layer, with a minimum overlap rate of not less than 20%;

[0104] Step 3.2) Take the copper rod and draw the required fan-shaped copper single wire with the required fan-shaped cross-section through the fan-shaped wire drawing die; for the shaped copper single wires in the same layer, the central angle of the fan ring is calculated according to the number of the shaped copper single wires;

[0105] The special-shaped copper monofilaments used in each layer are twisted in layers using a twisting machine, and each layer is pressed tightly after being twisted;

[0106] The twist direction of the outermost layer of shaped copper monofilaments is S direction; the pitch diameter ratio of the outermost layer of monofilaments does not exceed 15 times; the cross section of the outer conductor after twisting is the same as the conductor cross section, and the DC resistance of the conductor at 20℃ meets the requirements of GB / T3956 standard;

[0107] Step 3.3) wrapping a layer of semi-conductive nylon tape around the outer conductor to obtain a non-metallic wrapping layer, with a minimum overlap rate of not less than 20%;

[0108] In the step 4), a high-electricity thermoplastic elastomer insulation material is extruded outside the non-metallic wrapping layer outside the outer conductor to obtain an outer insulation layer, thereby obtaining a finished cable.

[0109] The formula system of the high-electrical thermoplastic elastomer insulating material used in step 2) is as follows: 30-50 parts of SEBS, 20-40 parts of polypropylene, 8-20 parts of white oil, 0.5-1.5 parts of antioxidant, 0.8-1.5 parts of lubricant, and 3-5 parts of silicone masterbatch according to the weight ratio;

[0110] The outer insulating material used in step 4) is obtained by adding CABOT carbon black (iodine absorption value is 29 mg / g) to the inner insulating material formula used in step 2), and the added mass is 1-2% of the total mass of the inner insulating material.

[0111] In this example, the formula system of step 2) is: SEBS 40 parts, polypropylene 30 parts, white oil 14 parts, antioxidant 1 part, lubricant 1.2 parts, silicone masterbatch 4 parts. The antioxidants are antioxidant 1010 and antioxidant 168, 0.5 parts each (products of Saint-LeCoultre), and the lubricant is polyethylene wax (9010W type product of Qingdao Sino New Materials). Step 4) The mass of CABOT carbon black added is 1.5% of the total mass of the inner insulation material.

[0112] During the trial production process, the different proportions of styrene-ethylene-butylene-styrene block copolymer SEBS and polypropylene PP have an impact on the performance of the insulation material. As the proportion of SEBS increases, the insulation material has better high temperature resistance and weathering test results, and also has better tensile properties and softness. The specific amount of other auxiliary raw materials in the insulation material and its impact on the final performance can be expected. For example, the amount of white oil affects the softness and colorability of the insulation material, the amount of antioxidant affects the aging test data of the insulation material, and the amount of silicone masterbatch affects the processing performance during the preparation process.

[0113] In step 1.2) of this example, the specification of the inner / outer conductor is 240mm 2 , please refer to the structure of the inner conductor Figure 2 The outer diameter of the inner conductor is controlled at 17.3±0.1mm.

[0114] In step 2), the extrusion process parameters of the inner insulation layer are set as follows:

[0115] A Φ90 extruder is used. Along the direction from feed to discharge, the temperatures of the 1st to 6th temperature zones of the extruder are 175±5°C, 180±5°C, 185±5°C, 185±5°C, 190±5°C and 195±5°C, respectively. The screw speed of the extruder is 20.0 rpm.

[0116] An extrusion die is used, and the die size is selected according to the outer diameter D1 of the inner conductor. The core diameter d1 = D1 + (2-3) mm, the sleeve diameter d2 = d1 + (2 + K) × the nominal thickness of the inner insulation layer, and K is 1.2; in this example, the nominal thickness of the inner insulation layer is 4.0 mm, and the thickness of the thinnest part of the inner insulation layer is 3.6 mm.

[0117] The average speed of the production line is 15-18m / min;

[0118] The inner insulation layer must pass the power frequency spark withstand voltage test during the extrusion process, the test voltage is: 25kV.

[0119] In this example, the core diameter is 19.5 mm, the sleeve diameter is 32.3 mm, and the average production line speed is 16 m / min.

[0120] In step 4), the extrusion process parameters of the outer insulation layer are set as follows:

[0121] A Φ120 extruder is used. Along the direction from feed to discharge, the temperatures of the 1st to 8th temperature zones of the extruder are 165±5°C, 170±5°C, 175±5°C, 180±5°C, 185±5°C, 190±5°C, 190±5°C and 195±5°C, respectively. The screw speed of the extruder is 25.0 rpm.

[0122] An extrusion die is used, and the die size is selected according to the outer diameter D2 of the previous process. The core diameter d3 = D2 + (2-3) mm, the sleeve diameter d4 = d3 + (2 + K) × the nominal thickness of the outer insulation layer, and K is 1.2; in this example, the nominal thickness of the outer insulation layer is 4.0 mm, and the thickness of the thinnest part of the outer insulation layer is 3.6 mm.

[0123] The average speed of the production line is 12-15 m / min;

[0124] The external insulation extrusion process must pass the power frequency spark withstand voltage test, the test voltage is: 25kV.

[0125] In this example, an extrusion die is used, the core diameter is 45.2 mm, the sleeve diameter is 58.0 mm, and the average production line speed is 12 m / min.

[0126] In step 1.1), a copper rod with a diameter of Φ8 mm is drawn into a circular copper monofilament with a diameter of Φ2.8 to 3.41 mm;

[0127] In step 1.2), a copper rod with a diameter of Φ8 mm is drawn into a special-shaped copper monofilament;

[0128] In step 1.3), the copper monofilaments are twisted in layers by a stranding machine, and arranged in 1+6+10+14, that is, from the inner layer to the outer layer, there are 1, 6, 10 and 14 monofilaments, respectively, divided into four layers and pressed three times; each layer is pressed and distributed in turn: 6-reel reel, 10-reel reel and 14-reel reel;

[0129] Figure 2-1 This is a schematic diagram of the cross section of the outermost layer (14 single wires) of the inner conductor's shaped copper single wire. Figure 2-2 This is a schematic cross-sectional view of the sub-outer layer (10 single wires) of the inner conductor's shaped copper single wire. Figure 2-3 This is a schematic cross-sectional view of the shaped copper wires of the inner conductor's secondary inner layer (6 wires). Figure 2-4 It is a schematic cross-sectional view of the circular copper monofilament in the center.

[0130] The twist direction of each layer of special-shaped copper single wire is set as S, Z, S from inside to outside. The twist direction of the second outer layer of single wire is Z direction, and the twist direction of the outermost layer of single wire is S direction.

[0131] The nominal thickness of the inner insulating layer in step 2) is 4.0 mm, the average thickness of the inner insulating layer is not less than the nominal thickness, and the thickness of the thinnest part of the inner insulating layer is not less than 3.8 mm;

[0132] The specifications of the semi-conductive nylon tape in steps 3.1) and 3.3) are 0.12 mm thick and 60 mm wide;

[0133] The drawing method of the shaped copper monofilament in step 3.2) is the same as that in step 1.2), and the twisting requirements of each layer of conductor are the same as those in step 1.3); wherein, the wire drawing must ensure that the corrugated arc angles of each layer of the shaped copper monofilament are consistent; when twisting in layers, each layer is pressed once after being twisted to ensure that there are no gaps between the monofilaments after twisting, so that the surface of the conductor is smooth, and the conductor resistivity is small after being pressed, and the conductive performance is good;

[0134] The nominal thickness of the outer insulation layer in step 4) is 4.0 mm, the average thickness of the outer insulation layer is not less than the nominal thickness, and the thickness of the thinnest insulation is not less than 3.8 mm.

[0135] According to the above method, the cable was trial-produced and sampled for multiple tests. The test results of the cable are shown below. Among them, the excellent rate of the product reached more than 98%.

[0136] Results: The main parameters of the cable in this example include (Tests 6 to 9 are performed by making samples of inner and outer insulation materials according to the corresponding standards):

[0137]

[0138] The conductors manufactured by this method have achieved or exceeded the standard requirements in the "conductor long-term operating temperature" and "short-circuit thermal stability current test" that reflect the performance of the conductor. After eliminating the conductor shielding structure, the conductor surface is made smooth by the design of the special-shaped conductor structure, which reduces the discharge amount in the "partial discharge test" and the results are far better than the standard requirements.

[0139] The cables manufactured by this method have far better results than the standard requirements in the "impact voltage test" which reflects the insulation performance of the cables.

[0140] In tests 6 to 9, which reflect the performance of the insulating material in this method, the results are far better than the standard requirements.

Claims

1. A lightweight cross-connected grounded coaxial cable, characterized in that It includes an inner conductor, an inner insulating layer, an outer conductor and an outer insulating layer extruded outside the outer conductor; The inner conductor is composed of twisted copper monofilaments; an insulating material is wrapped around the inner conductor to form an inner insulating layer; an outer conductor with the same cross-section as the inner conductor is coaxially wound around the inner insulating layer; the outer conductor is composed of twisted copper monofilaments with special cross-sections; an insulating material is wrapped around the outer conductor to form an outer insulating layer; The structure of the inner conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside outside the central circular copper monofilament; the cross section of the central circular copper monofilament is circular; the cross sections of the other layers of conductors are annular, and each layer of conductors is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the annular cross section of the conductor; The structure of the outer conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside; the cross section of each layer of conductor is annular, and each layer of conductor is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the ring cross section of the conductor; In the inner and outer conductors, the twisting directions of adjacent layers are opposite, and the twisting direction of the outermost layer is S direction.

2. The lightweight cross-connected grounded coaxial cable according to claim 1, characterized in that There is a non-metallic tape wrapping layer between the inner insulating layer and the outer conductor; there is also a non-metallic tape wrapping layer between the outer conductor and the outer insulating layer.

3. The lightweight cross-connected grounded coaxial cable according to claim 1, characterized in that The cross-sectional shapes of the shaped copper monofilaments constituting the conductors of the same layer are the same.

4. A method for manufacturing a lightweight cross-connected grounded coaxial cable, characterized in that The structure of the cable includes an inner conductor, an inner insulating layer, an outer conductor and an outer insulating layer extruded outside the outer conductor; The inner conductor is composed of twisted copper monofilaments; an insulating material is wrapped around the inner conductor to form an inner insulating layer; an outer conductor with the same cross-section as the inner conductor is coaxially wound around the inner insulating layer; the outer conductor is composed of twisted copper monofilaments with special cross-sections; an insulating material is wrapped around the outer conductor to form an outer insulating layer; The structure of the inner conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside outside the central circular copper monofilament; the cross section of the central circular copper monofilament is circular; the cross sections of the other layers of conductors are annular, and each layer of conductors is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the annular cross section of the conductor; The structure of the outer conductor is as follows: it is composed of multiple layers of conductors pressed in sequence from the inside to the outside; the cross section of each layer of conductor is annular, and each layer of conductor is respectively composed of twisted copper monofilaments with fan-shaped cross sections; for the conductors of the same layer, the fan-shaped cross section of the monofilament is a part of the ring cross section of the conductor; In the inner and outer conductors, the twisting directions of adjacent layers are opposite, and the twisting direction of the outermost layer is S direction; The cross-sectional shapes of the shaped copper monofilaments constituting the conductors of the same layer are the same; The manufacturing method of the cable comprises the steps of: 1) Manufacturing inner conductor; 2) wrapping the inner conductor obtained in step 1) with an inner insulating layer to obtain an insulated wire core; 3) manufacturing an outer conductor outside the insulated wire core obtained in step 2), the steps comprising: 3.1) Manufacturing non-metallic wrapping layer; 3.2) manufacturing an outer conductor layer; 3.3) Manufacturing non-metallic wrapping layer; 4) Manufacturing the outer insulation layer; The step 1) comprises: 1.1) Making round copper monofilament: Take the copper rod and draw it into a round copper monofilament of the required diameter. The tolerance requirement of the copper monofilament is ±0.01mm; the elongation of the copper monofilament is ≥35%, and the resistivity of the copper monofilament does not exceed 0.017241Ω·mm 2 / m; 1.2) Making special-shaped copper monofilament: Take the copper rod and draw the required fan-shaped copper monofilament with the required fan-shaped cross-section through the fan-shaped wire drawing die; for the same layer of shaped copper monofilaments, the central angle of the fan ring is calculated according to the number of shaped copper monofilaments; wire drawing must ensure that the corrugated arc angles of the shaped copper monofilaments in each layer are consistent; 1.3) Shaped copper monofilament twisted: The special-shaped copper monofilaments used in each layer are twisted in layers using a twisting machine, and each layer is pressed tightly after being twisted; The twist direction of the outermost layer of shaped copper monofilaments is S direction; the pitch diameter ratio of the outermost layer of monofilaments does not exceed 15 times; The requirements for the inner conductor obtained through steps 1.1) to 1.3) are as follows: the DC resistance of the conductor at 20°C meets the requirements of GB / T3956 standard; the outer diameter of the inner conductor is controlled within the range of 12.8 to 23.3 mm; In the step 2), a high-electricity thermoplastic elastomer insulation material is extruded outside the inner conductor to obtain an inner insulating layer, thereby obtaining an insulated wire core; In the step 3): Step 3.1) wrapping a layer of semi-conductive nylon tape around the insulated wire core to obtain a non-metallic wrapping layer, with a minimum overlap rate of not less than 20%; Step 3.2) Take a copper rod and draw a shaped copper monofilament of the required fan ring cross section through a fan-shaped wire drawing die; for the shaped copper monofilaments of the same layer, the central angle of the fan ring is calculated according to the number of shaped copper monofilaments; the wire drawing must ensure that the corrugated arc angles of the shaped copper monofilaments of each layer are consistent; the shaped copper monofilaments used in each layer are layered and twisted by a twisting machine, and each layer is pressed once after twisting to ensure that there is no gap between the monofilaments after twisting, so that the conductor surface is smooth, the conductor resistivity is small after pressing, and the conductive performance is good; The twist direction of the outermost layer of shaped copper monofilaments is S direction; the pitch diameter ratio of the outermost layer of monofilaments does not exceed 15 times; the cross section of the outer conductor after twisting is the same as the conductor cross section, and the DC resistance of the conductor at 20℃ meets the requirements of GB / T3956 standard; Step 3.3) wrapping a layer of semi-conductive nylon tape around the outer conductor to obtain a non-metallic wrapping layer, with a minimum overlap rate of not less than 20%; In the step 4), a high-electricity thermoplastic elastomer insulation material is extruded outside the non-metallic wrapping layer outside the outer conductor to obtain an outer insulation layer, thereby obtaining a finished cable.

5. The method for manufacturing a lightweight cross-connected grounded coaxial cable according to claim 4, characterized in that In step 2), the extrusion process parameters of the inner insulation layer are set as follows: A Φ90 extruder is used. Along the direction from feed to discharge, the temperatures of the 1st to 6th temperature zones of the extruder are 175±5°C, 180±5°C, 185±5°C, 185±5°C, 190±5°C and 195±5°C, respectively. The screw speed of the extruder is 20.0 rpm. An extrusion die is used, and the die size is selected according to the outer diameter D1 of the inner conductor, the core diameter d1 = D1 + (2-3) mm, the sleeve diameter d2 = d1 + (2 + K) × the nominal thickness of the inner insulation layer, K is 1.2; the average thickness of the inner insulation layer is calculated by the design of the average electric field strength to which the cable insulation is subjected, and is not less than the nominal thickness; The average speed of the production line is 15-18m / min; The inner insulation layer must pass the power frequency spark withstand voltage test during the extrusion process, the test voltage is: 25kV.

6. The method for manufacturing a lightweight cross-connected grounded coaxial cable according to claim 4, characterized in that In step 4), the extrusion process parameters of the outer insulation layer are set as follows: A Φ120 extruder is used. Along the direction from feed to discharge, the temperatures of the 1st to 8th temperature zones of the extruder are 165±5°C, 170±5°C, 175±5°C, 180±5°C, 185±5°C, 190±5°C, 190±5°C and 195±5°C, respectively. The screw speed of the extruder is 25.0 rpm. An extrusion die is used, and the die size is selected according to the outer diameter D2 of the previous process, the core diameter d3 = D2 + (2-3) mm, the die sleeve diameter d4 = d3 + (2 + K) × the nominal thickness of the outer insulation layer, and K is 1.2; The nominal thickness of the outer insulation layer is equal to the nominal thickness of the inner insulation layer, and the average thickness of the outer insulation layer is not less than the nominal thickness; The average speed of the production line is 12-15 m / min; The external insulation extrusion process must pass the power frequency spark withstand voltage test, the test voltage is: 25kV.

7. The method for manufacturing a lightweight cross-connected grounded coaxial cable according to claim 4, characterized in that In step 1.1), a copper rod with a diameter of Φ8 mm is drawn into a circular copper monofilament with a diameter of Φ2.8 to 3.41 mm; In step 1.2), a copper rod with a diameter of Φ8 mm is drawn into a special-shaped copper monofilament; In step 1.3), the copper monofilaments are twisted in layers by a stranding machine, and arranged in 1+6+10+14, that is, from the inner layer to the outer layer, there are 1, 6, 10 and 14 monofilaments, respectively, divided into four layers and pressed three times; each layer is pressed and distributed in turn: 6-reel reel, 10-reel reel and 14-reel reel; The twist direction of each layer of special-shaped copper single wire is set as S, Z, S from inside to outside. The twist direction of the second outer layer of single wire is Z direction, and the twist direction of the outermost layer of single wire is S direction. The nominal thickness of the inner insulating layer in step 2) is 4.0 mm, the average thickness of the inner insulating layer is not less than the nominal thickness, and the thickness of the thinnest part of the inner insulating layer is not less than 3.6 mm; The specifications of the semi-conductive nylon tape in steps 3.1) and 3.3) are 0.12 mm thick and 60 mm wide; The method for drawing the shaped copper monofilament in step 3.2) is the same as that in step 1.2), and the requirements for twisting the conductors of each layer are the same as those in step 1.3); The nominal thickness of the outer insulation layer in step 4) is 4.0 mm, the average thickness of the outer insulation layer is not less than the nominal thickness, and the thickness of the thinnest insulation is not less than 3.6 mm.

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