Heat-resistant and moisture-proof radio frequency coaxial cable and production process

Abstract

The present invention relates to the technical field of coaxial radio frequency cables, and in particular to a heat-resistant and moisture-proof radio frequency coaxial cable and a production process, comprising an inner conductor, an inner skin layer, a foamed insulation layer, an outer skin layer, an outer conductor, a heat insulation layer and a sheath arranged in sequence from the inside to the outside, the outer conductor adopts an annular corrugated outer conductor with an annular groove, the heat insulation layer comprises a talcum powder layer and a heat insulation belt, the talcum powder layer is adhered to the surface of the outer conductor, and the heat insulation belt is wound on the talcum powder layer. By adhering talcum powder on the surface of the outer conductor to form a talcum powder layer, heat and water vapor are isolated from being transmitted to the foamed insulation layer through the sheath, thereby optimizing the attenuation performance index of the coaxial radio frequency cable, and the heat insulation belt can further improve the heat insulation performance, and the heat insulation belt can wrap the talcum powder to reduce the possibility of the talcum powder falling, and at the same time, because the outer conductor adopts an annular corrugated outer conductor with an annular groove, a heat insulation area is formed between the annular groove and the heat insulation belt, further improving the heat insulation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of coaxial radio frequency cables, and in particular to a heat-resistant and moisture-proof radio frequency coaxial cable and a production process. Background Art

[0002] RF cables are mainly used as connecting lines between equipment and antennas. The main performance indicators of coaxial cables are voltage standing wave ratio, attenuation constant, and impedance.

[0003] Since RF coaxial cables are used in special places such as indoors and outdoors, the sheath is made of black low-smoke halogen-free flame-retardant polyolefin or black polyethylene. Black easily absorbs ultraviolet rays, causing the internal temperature of the RF cable to rise, causing the attenuation of the cable to deteriorate.

[0004] The attenuation constant of RF coaxial cable is mainly conductor attenuation + dielectric attenuation, where conductor attenuation is divided into inner conductor attenuation and outer conductor attenuation. Conductor attenuation mainly depends on the resistance of the material used, and dielectric attenuation is mainly determined by the dielectric constant and foaming degree of the foaming material.

[0005] The attenuation performance is closely related to the dielectric constant of the material. Water is a polar molecule. If the foaming layer absorbs moisture, it will cause the cable to generate heat when transmitting electricity. This heat is caused by power loss in the cable, and this loss will increase the attenuation of the cable. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in order to solve the technical problems in the prior art, the present invention provides a heat-resistant and moisture-proof radio frequency coaxial cable and a production process.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a heat-resistant and moisture-proof radio frequency coaxial cable, including an inner conductor, an inner skin layer, a foamed insulation layer, an outer skin layer, an outer conductor, a thermal insulation layer and a sheath arranged in sequence from the inside to the outside, the outer conductor adopts an annular corrugated outer conductor with an annular groove, the thermal insulation layer includes a talcum powder layer and an insulating belt, the talcum powder layer is adhered to the surface of the outer conductor, and the insulating belt is wound on the talcum powder layer.

[0008] The heat-resistant and moisture-proof radio frequency coaxial cable of the present invention forms a talcum powder layer by adhering talcum powder on the surface of the outer conductor, thereby isolating the path of heat and water vapor being transmitted to the foamed insulating layer through the sheath, thereby optimizing the attenuation performance index of the coaxial radio frequency cable, and the thermal insulation belt can further improve the thermal insulation performance. At the same time, the thermal insulation belt can wrap the talcum powder to reduce the possibility of the talcum powder falling. At the same time, since the outer conductor adopts an annular wrinkled outer conductor with an annular groove, a thermal insulation area is formed between the annular groove and the thermal insulation belt, further improving the thermal insulation effect.

[0009] Furthermore, the thermal insulation belt is made of ABS plastic.

[0010] A production process, based on the above-mentioned heat-resistant and moisture-proof radio frequency coaxial cable, comprises the following steps:

[0011] S1. Production of the inner conductor: The copper strip is subjected to a forming process to form a round tube shape with the tube seam facing upward and closely connected, and then welded to form a closed and smooth copper tube inner conductor;

[0012] S2, extruding the inner skin layer: the inner skin layer is coated on the outer surface of the inner conductor in S1, and the inner skin layer is uniformly extruded and coated on the outer surface of the inner conductor after drawing and cleaning. When the inner skin layer is extruded and coated on the outer surface of the inner conductor, a vacuum treatment is also performed to make the inner skin layer closely contact with the inner conductor. After the inner skin layer is extruded and coated on the outer surface of the inner conductor, the inner conductor extruded with the inner skin layer is cooled;

[0013] S3, extrusion packing the foamed insulation layer and the outer skin layer: the foamed insulation layer and the outer skin layer are coated on the outer surface of the inner skin layer of S2, the foamed insulation layer is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and gas, the polyethylene includes high-density polyethylene and low-density polyethylene, the weight percentage of the high-density polyethylene, the low-density polyethylene and the nucleating agent is 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent respectively, the foaming degree is 65-75%, and the insulation outer diameter is 42.7±0.40mm;

[0014] S4, the outer conductor manufacturing: cleaning the surface of the copper strip of the outer conductor, fine-cutting the cleaned copper strip of the outer conductor to make the width of the copper strip of the outer conductor uniform, forming the finely cut copper strip of the outer conductor, forming the copper strip of the outer conductor into a round tube with the tube seam upward and closely connected, and then welding to form a closed and smooth copper tube outer conductor, calibrating the copper tube outer conductor, placing the inner conductor with the foamed insulation layer and the outer skin layer extruded in S3 into the calibrated copper tube outer conductor, and corrugating the outer surface of the copper tube outer conductor, rolling the outer surface of the copper tube outer conductor into an annular corrugated outer conductor with an annular groove;

[0015] S5, the preparation of the heat insulation layer: passing the outer conductor of S4 through the powder adding device to form a talcum powder layer on the surface of the outer conductor, and then winding an insulation belt on the talcum powder layer;

[0016] S6. Extruding the sheath: the sheath material is linear low-density polyethylene or low-smoke halogen-free flame-retardant polyolefin, which is dried and melted, and the molten polyethylene sheath material or low-smoke halogen-free flame-retardant polyolefin sheath material is extruded and coated on the outer surface of the outer conductor in step five. When the sheath is extruded and coated on the outer surface of the outer conductor, a vacuum treatment is also performed. The sheath is in close contact with the outer surface of the outer conductor, and is completed. It is then cooled in a hot water tank at a temperature of 35°C, and then cooled in a cold water tank at room temperature to form the sheath.

[0017] Furthermore, in step S4, when the outer conductor is rolled, lubricating liquid is added to the surface of the outer conductor to cool the outer conductor, and the lubricating oil on the surface of the outer conductor is used to adhere to the talcum powder after entering the powder adding device.

[0018] Furthermore, the powder adding device comprises a shell, a powder heating mechanism and a powder circulation mechanism, a powder adding area and a powder scraping area are provided in the shell, and the outer conductor passes through the powder adding area and the powder scraping area in sequence;

[0019] The powder adding area is provided with a stirring component to stir the talcum powder, and the powder scraping area is provided with a powder scraping component to scrape off excess talcum powder on the surface of the conductor.

[0020] Furthermore, the powder circulation mechanism includes a solid conveying pump and a conveying pipe. A collecting hopper is provided at the bottom of the shell. The powder adding area and the powder scraping area are both connected to the collecting hopper. The bottom of the collecting hopper is connected to the solid conveying pump. The output end of the solid conveying pump is connected to the conveying pipe. A cover plate is provided on the top of the shell. The end of the conveying pipe away from the solid conveying pump is connected to the cover plate.

[0021] Furthermore, the powder heating mechanism comprises a heating coil, and the heating coil is arranged in the side wall of the shell.

[0022] Furthermore, the powder scraper assembly includes a powder scraper ring and a scraper piece, the outer conductor passes through the powder scraper ring, and there are multiple scraper pieces along the circumferential array of the powder scraper ring. The scraper piece includes a scraper barrel and a scraper ball, the scraper barrel is connected to the powder scraper ring, the scraper ball is arranged in the scraper barrel, and the scraper ball is partially located outside the scraper barrel. The opening of the scraper barrel is bent inward to limit the scraper ball, and the scraper ball is used to contact the surface of the outer conductor. A first compression spring is provided in the scraper barrel, one end of the first compression spring abuts against the scraper ball, and the other end abuts against an end of the scraper barrel away from the scraper ball.

[0023] Furthermore, the scraper member also includes a fixed cylinder, which is fixedly connected to the powder scraper ring. The scraper cylinder is inserted into the fixed cylinder, and a second compression spring is provided in the fixed cylinder. One end of the second compression spring abuts against the scraper cylinder, and the other end abuts against an end of the fixed cylinder away from the scraper cylinder.

[0024] Furthermore, a first rotating member is provided on the shell, an output end of the first rotating member is connected to a first gear, the powder scraping ring is rotatably connected to the shell, a second gear is provided on the powder scraping ring, and the first gear is meshed with the second gear.

[0025] The beneficial effects of the present invention are:

[0026] By adhering talcum powder on the surface of the outer conductor to form a talcum powder layer, the path of heat and water vapor being transmitted to the foamed insulation layer through the sheath is isolated, thereby optimizing the attenuation performance index of the coaxial RF cable, and the thermal insulation belt can further improve the thermal insulation performance. At the same time, the thermal insulation belt can wrap the talcum powder to reduce the possibility of talcum powder falling. At the same time, since the outer conductor adopts an annular wrinkled outer conductor with an annular groove, a thermal insulation area is formed between the annular groove and the thermal insulation belt, further improving the thermal insulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0028] Figure 1 The invention is a schematic structural diagram of a heat-resistant and moisture-proof radio frequency coaxial cable.

[0029] Figure 2 The present invention is a schematic diagram of a process for producing a heat-resistant and moisture-proof radio frequency coaxial cable.

[0030] Figure 3 It is a schematic diagram of the structure of powder adding in the present invention.

[0031] Figure 4 It is a schematic structural diagram of the powder adding area and the powder scraping area in the present invention.

[0032] Figure 5 It is a structural schematic diagram of the scraper member in the present invention.

[0033] In the figure: 1. inner conductor; 11. inner skin layer; 12. foamed insulation layer; 13. outer skin layer; 14. outer conductor; 15. thermal insulation layer; 16. sheath; 2. shell; 21. powder adding area; 22. powder scraping area; 23. cover plate; 3. powder circulation mechanism; 31. solid conveying pump; 32. conveying pipe; 4. scraping assembly; 41. powder scraping ring; 42. scraping member; 421. fixed cylinder; 422. scraping cylinder; 423. second compression spring; 424. scraping ball; 425. first compression spring; 43. first rotating member; 431. first gear; 432. second gear; 5. stirring assembly; 51. second rotating member; 52. propeller. DETAILED DESCRIPTION

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The invention discloses a heat-resistant and moisture-proof radio frequency coaxial cable and a production process.

[0037] Reference Figure 1A heat-resistant and moisture-proof radio frequency coaxial cable comprises an inner conductor 1, an inner skin layer 11, a foamed insulating layer 12, an outer skin layer 13, an outer conductor 14, a heat-insulating layer 15 and a sheath 16 which are arranged in sequence from the inside to the outside. The outer conductor 14 adopts an annular corrugated outer conductor 14 with an annular groove. The heat-insulating layer 15 comprises a talcum powder layer and a heat-insulating belt. The talcum powder layer is adhered to the surface of the outer conductor 14, and the heat-insulating belt is wound on the talcum powder layer. By adhering talcum powder on the surface of the outer conductor 14 to form a talcum powder layer, the path of heat and water vapor passing through the sheath 16 to the foamed insulating layer 12 is isolated, thereby realizing the optimization of the attenuation performance index of the coaxial radio frequency cable, and the heat-insulating belt can further improve the heat-insulating performance. At the same time, the heat-insulating belt can wrap the talcum powder to reduce the possibility of the talcum powder falling. At the same time, since the outer conductor 14 adopts an annular corrugated outer conductor 14 with an annular groove, a heat-insulating area is formed between the annular groove and the heat-insulating belt, further improving the heat-insulating effect.

[0038] It should be noted that the heat insulating belt can be made of ABS plastic. Talc powder is a magnesium silicate mineral talc family talc, the main component of which is hydrated magnesium silicate, which is crushed, treated with hydrochloric acid, washed with water and dried.

[0039] In addition, the foamed insulation layer 12 is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and a gas, wherein the polyethylene includes high-density polyethylene and low-density polyethylene, and the weight percentages of high-density polyethylene, low-density polyethylene and a nucleating agent are 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent, respectively, and the foaming degree is 60-70%. The gas is a mixture of CO2 and C4F8, or a mixture of N2 and C4F8, and the fully closed pore foaming degree is 65-75%.

[0040] A production process, based on the above heat-resistant and moisture-proof radio frequency coaxial cable, referring to Figure 2 , including the following steps:

[0041] S1. Production of inner conductor 1: The copper strip is subjected to a forming process to form a round tube shape with the tube seam facing upward and closely connected, and then welded to form a closed and smooth copper tube inner conductor 1;

[0042] S2, extruding an inner cortex layer 11: the inner cortex layer 11 is coated on the outer surface of the inner conductor 1 of S1, and the inner cortex layer 11 is uniformly extruded and coated on the outer surface of the inner conductor 1 after drawing and cleaning. When the inner cortex layer 11 is extruded and coated on the outer surface of the inner conductor 1, a vacuum treatment is also performed to make the inner cortex layer 11 in close contact with the inner conductor 1. After the inner cortex layer 11 is extruded and coated on the outer surface of the inner conductor 1, the inner conductor 1 extruded with the inner cortex layer 11 is cooled;

[0043] S3, extruded foamed insulation layer 12 and outer skin layer 13: The inner skin layer 11 of S2 is coated with a foamed insulation layer 12 and an outer skin layer 13, the foamed insulation layer 12 is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and a gas, the polyethylene includes high-density polyethylene and low-density polyethylene, the weight percentages of high-density polyethylene, low-density polyethylene and nucleating agent are 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent respectively, the foaming degree is 65-75%, and the insulation outer diameter is 42.7±0.40mm;

[0044] S4, outer conductor 14 production: the copper strip of the outer conductor 14 is cleaned on the surface, the cleaned copper strip of the outer conductor 14 is finely cut to make the width of the copper strip of the outer conductor 14 uniform, the finely cut copper strip of the outer conductor 14 is molded, the copper strip of the molded outer conductor 14 is formed into a rounded tube with the tube seam facing upward and closely connected, and then welded to form a closed and smooth copper tube outer conductor 14, the copper tube outer conductor 14 is rounded, the inner conductor 1 with the extruded foam insulation layer 12 and the outer skin layer 13 in S3 is placed in the copper tube outer conductor 14 after rounding, and the outer surface of the copper tube outer conductor 14 is corrugated to roll the outer surface of the copper tube outer conductor 14 into an annular corrugated outer conductor 14 with annular grooves. When the outer conductor 14 is rolled, lubricating liquid is added to the surface of the outer conductor 14 to cool the outer conductor 14, and the lubricating oil on the surface of the outer conductor 14 is used to adhere to the talcum powder after entering the powder adding device.

[0045] S5, making the heat insulation layer 15: passing the outer conductor 14 of S4 through the powder adding device to form a talcum powder layer on the surface of the outer conductor 14, and then winding an insulation belt on the talcum powder layer;

[0046] S6, extruded sheath 16: the material of sheath 16 is linear low density polyethylene or low smoke halogen-free flame retardant polyolefin, the linear low density polyethylene or low smoke halogen-free flame retardant polyolefin is dried and melted, the melted polyethylene sheath 16 material or low smoke halogen-free flame retardant polyolefin sheath 16 material is extruded and coated on the outer surface of the outer conductor 14 in step five, and the sheath 16 is also vacuumed when it is extruded and coated on the outer surface of the outer conductor 14. The sheath 16 is made after it is in close contact with the outer surface of the outer conductor 14, and then cooled in a hot water tank with a temperature of 35°C, and then cooled in a cold water tank with room temperature to make the sheath 16.

[0047] Specifically, refer to Figures 3 to 5 The powder adding device includes a shell 2, a powder heating mechanism and a powder circulation mechanism 3. A powder adding area 21 and a powder scraping area 22 are provided in the shell 2. The outer conductor 14 passes through the powder adding area 21 and the powder scraping area 22 in sequence. A stirring component 5 is provided in the powder adding area 21 to stir the talcum powder, and a powder scraping component is provided in the powder scraping area 22 to scrape off excess talcum powder on the surface of the outer conductor 14.

[0048] More specifically, the powder circulation mechanism 3 includes a solid delivery pump 31 and a delivery pipe 32. The bottom of the shell 2 is fixedly connected with a gathering hopper. The powder adding area 21 and the powder scraping area 22 are both connected to the gathering hopper so that the talcum powder can be gathered in the gathering hopper. The bottom of the gathering hopper is connected to the solid delivery pump 31, and the output end of the solid delivery pump 31 is connected to the delivery pipe 32. A cover plate 23 is provided on the top of the shell 2. The end of the delivery pipe 32 away from the solid delivery pump is connected to the cover plate 23, thereby realizing the circulation of talcum powder, and cooperating with the stirring component 5 and the powder heating mechanism to obtain dry and uniform talcum powder, so as to better adhere to the surface of the outer conductor 14.

[0049] The powder heating mechanism includes a heating coil, which is arranged in the side wall of the housing 2 to heat the talcum powder. The stirring assembly 5 includes a second rotating member 51 and a propeller 52. The second rotating member 51 is fixed outside the housing 2. The output end of the second rotating member 51 extends into the housing 2 and is fixedly connected to the propeller 52, thereby facilitating the stirring of the talcum powder to obtain talcum powder with uniform particles. The propeller 52 is located below the outer conductor 14, and the outer conductor 14 passes through the middle of the talcum powder in the housing 2 and absorbs a layer of talcum powder through the lubricating oil.

[0050] The powder scraping assembly includes a powder scraping ring 41 and a scraping piece 42. The outer conductor 14 passes through the powder scraping ring 41. There are multiple scraping pieces 42 along the circumferential array of the powder scraping ring 41. The scraping piece 42 includes a fixed cylinder 421, a scraping cylinder 422 and a scraping ball 424. The fixed cylinder 421 is fixedly connected to the powder scraping ring 41. The scraping cylinder 422 is inserted into the fixed cylinder 421. A second compression spring 423 is provided in the fixed cylinder 421. One end of the second compression spring 423 abuts against the scraping cylinder 422, and the other end abuts against an end of the fixed cylinder 421 away from the scraping cylinder 422. The scraper ball 424 is arranged in the scraper barrel 422, and part of the scraper ball 424 is located outside the scraper barrel 422. The opening of the scraper barrel 422 is bent inward to limit the scraper ball 424. The scraper ball 424 is used to contact the surface of the outer conductor 14. A first compression spring 425 is arranged in the scraper barrel 422, and one end of the first compression spring 425 abuts against the scraper ball 424, and the other end abuts against one end of the scraper barrel 422 away from the scraper ball 424. The pressure of the first compression spring 425 is greater than the pressure of the second compression spring 423, so that when working, the second compression spring 423 will be compressed first.

[0051] When the outer conductor 14 passes through the scraper ring 41, the scraper balls 424 of the plurality of scraper members 42 abut against the surface of the outer conductor 14 to scrape off the talcum powder on the surface of the outer conductor 14. A plurality of scraper members are provided along the conveying direction of the outer conductor 14, and the scraper members 42 of the plurality of scraper members are staggered so as to better cover the surface of the outer conductor 14 and scrape off the excess talcum powder on the surface of the outer conductor 14.

[0052] The housing 2 is fixedly connected with a first rotating member 43, and the output end of the first rotating member 43 is coaxially fixedly connected with a plurality of first gears 431. The powder scraping ring 41 is rotatably connected with the housing 2, and each powder scraping ring 41 is coaxially fixedly connected with a second gear 432. The plurality of first gears 431 correspond to the plurality of second gears 432 one by one and mesh with each other. The first rotating member 43 drives the powder scraping ring 41 to rotate, so that the scraping ball 424 synchronously moves in a circumferential direction on the surface of the outer conductor 14. Both the first rotating member 43 and the second rotating member 51 can adopt stepper motors.

[0053] Working principle: By adhering talcum powder on the surface of the outer conductor 14 to form a talcum powder layer, the path of heat and water vapor being transmitted to the foamed insulation layer 12 through the sheath 16 is isolated, thereby optimizing the attenuation performance index of the coaxial RF cable, and the thermal insulation belt can further improve the thermal insulation performance. At the same time, the thermal insulation belt can wrap the talcum powder to reduce the possibility of talcum powder falling. At the same time, since the outer conductor 14 adopts an annular corrugated outer conductor 14 with an annular groove, a thermal insulation area is formed between the annular groove and the thermal insulation belt, further improving the thermal insulation effect.

[0054] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A production process for a heat-resistant and moisture-proof radio frequency coaxial cable, characterized in that: The heat-resistant and moisture-proof radio frequency coaxial cable comprises an inner conductor (1), an inner skin layer (11), a foamed insulating layer (12), an outer skin layer (13), an outer conductor (14), a heat insulating layer (15) and a sheath (16) which are arranged in sequence from the inside to the outside. The outer conductor (14) is an annular corrugated outer conductor (14) having an annular groove. The heat insulating layer (15) comprises a talcum powder layer and a heat insulating belt. The talcum powder layer is adhered to the surface of the outer conductor (14). The heat insulating belt is wound on the talcum powder layer. A heat insulating area is formed between the annular groove and the heat insulating belt. The production process comprises the following steps: The outer surface of the copper tube outer conductor (14) is corrugated to form an annular corrugated outer conductor (14) having an annular groove, and lubricating oil is added to the surface of the outer conductor (14) during the corrugation process of the outer conductor (14) to cool the outer conductor (14); The outer conductor (14) is then passed through a powder adding device, and the lubricating oil on the surface of the outer conductor (14) adheres to the talcum powder after the outer conductor (14) enters the powder adding device to form a talcum powder layer, and then an insulating belt is wound on the talcum powder layer.

2. A production process according to claim 1, characterized in that: The insulation belt is made of ABS plastic.

3. A production process according to claim 1, characterized in that: The following steps are also included: S1. Manufacturing the inner conductor (1): forming the copper strip into a round tube shape with the seam facing upward and tightly connected, and then welding to form a closed and smooth copper tube inner conductor (1); S2, extruding the inner skin layer (11): the inner skin layer (11) is coated on the outer surface of the inner conductor (1) of S1, and the inner skin layer (11) is uniformly extruded and coated on the outer surface of the inner conductor (1) after drawing and cleaning. When the inner skin layer (11) is extruded and coated on the outer surface of the inner conductor (1), a vacuum treatment is also performed to make the inner skin layer (11) and the inner conductor (1) closely contact each other. After the inner skin layer (11) is extruded and coated on the outer surface of the inner conductor (1), the inner conductor (1) extruded with the inner skin layer (11) is cooled; S3, extruding the foamed insulation layer (12) and the outer skin layer (13): the foamed insulation layer (12) and the outer skin layer (13) are coated on the outer surface of the inner skin layer (11) of S2, the foamed insulation layer (12) is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and gas, the polyethylene includes high-density polyethylene and low-density polyethylene, the weight percentage of the high-density polyethylene, the low-density polyethylene and the nucleating agent is 45% of high-density polyethylene, 51% of low-density polyethylene and 4% of nucleating agent respectively, the foaming degree is 65-75%, and the insulation outer diameter is 42.7±0.40mm; S4, manufacturing the outer conductor (14): cleaning the surface of the copper strip of the outer conductor (14), fine-cutting the cleaned copper strip of the outer conductor (14) to make the width of the copper strip of the outer conductor (14) uniform, molding the finely cut copper strip of the outer conductor (14), forming the copper strip of the outer conductor (14) into a rounded tube with the tube seam facing upward and tightly connected, and then welding to form a closed and smooth copper tube outer conductor (14), calibrating the copper tube outer conductor (14), placing the inner conductor (1) with the foamed insulation layer (12) and the outer skin layer (13) extruded in S3 into the calibrated copper tube outer conductor (14), and corrugating the outer surface of the copper tube outer conductor (14), rolling the outer surface of the copper tube outer conductor (14) into an annular corrugated outer conductor (14) with an annular groove; S5, the thermal insulation layer (15) is prepared by passing the outer conductor (14) of S4 through a powder adding device to form a talcum powder layer on the surface of the outer conductor (14), and then winding an insulation belt on the talcum powder layer; S6. Extruding the sheath (16): the sheath (16) is made of linear low-density polyethylene or low-smoke halogen-free flame-retardant polyolefin. The linear low-density polyethylene or the low-smoke halogen-free flame-retardant polyolefin is dried and melted, and the melted polyethylene sheath (16) material or the low-smoke halogen-free flame-retardant polyolefin sheath (16) material is extruded and coated on the outer surface of the outer conductor (14) in step five. When the sheath (16) is extruded and coated on the outer surface of the outer conductor (14), a vacuum treatment is also performed. After the sheath (16) is in close contact with the outer surface of the outer conductor (14), the sheath (16) is manufactured. Subsequently, the sheath is cooled in a hot water tank at a temperature of 35°C, and then cooled in a cold water tank at room temperature to manufacture the sheath (16).

4. A production process as claimed in claim 3, characterized in that: The powder adding device comprises a shell (2), a powder heating mechanism and a powder circulation mechanism (3); a powder adding area (21) and a powder scraping area (22) are provided in the shell (2); and the outer conductor (14) passes through the powder adding area (21) and the powder scraping area (22) in sequence; The powder adding area (21) is provided with a stirring component (5) for stirring the talcum powder, and the powder scraping area (22) is provided with a powder scraping component for scraping off excess talcum powder on the surface of the external conductor (14).

5. A production process as claimed in claim 4, characterized in that: The powder circulation mechanism (3) comprises a solid delivery pump (31) and a delivery pipe (32); a collecting hopper is provided at the bottom of the shell (2); the powder adding area (21) and the powder scraping area (22) are both connected to the collecting hopper; the bottom of the collecting hopper is connected to the solid delivery pump (31); the output end of the solid delivery pump (31) is connected to the delivery pipe (32); a cover plate (23) is provided at the top of the shell (2); and the end of the delivery pipe (32) away from the solid delivery pump is connected to the cover plate (23).

6. A production process according to claim 5, characterized in that: The powder heating mechanism comprises a heating coil, and the heating coil is arranged in the side wall of the shell (2).

7. A production process according to claim 6, characterized in that: The powder scraping assembly comprises a powder scraping ring (41) and a scraping member (42), the outer conductor (14) passes through the powder scraping ring (41), a plurality of the scraping members (42) are arranged in a circumferential array along the powder scraping ring (41), the scraping member (42) comprises a scraping cylinder (422) and a scraping ball (424), the scraping cylinder (422) is connected to the powder scraping ring (41), the scraping ball (424) is arranged in the scraping cylinder (422), and the scraping ball (424) is arranged in the scraping cylinder (422). 4) is partially located outside the scraper barrel (422), the opening of the scraper barrel (422) is bent inward to limit the scraper ball (424), the scraper ball (424) is used to contact the surface of the outer conductor (14), and a first compression spring (425) is provided in the scraper barrel (422), one end of the first compression spring (425) is in contact with the scraper ball (424), and the other end is in contact with an end of the scraper barrel (422) away from the scraper ball (424).

8. A production process according to claim 7, characterized in that: The scraper member (42) further comprises a fixed cylinder (421), wherein the fixed cylinder (421) is fixedly connected to the powder scraping ring (41), the scraper cylinder (422) is inserted into the fixed cylinder (421), a second compression spring (423) is arranged in the fixed cylinder (421), one end of the second compression spring (423) abuts against the scraper cylinder (422), and the other end abuts against an end of the fixed cylinder (421) away from the scraper cylinder (422).

9. A production process according to claim 7, characterized in that: The housing (2) is provided with a first rotating member (43), the output end of the first rotating member (43) is connected to a first gear (431), the powder scraping ring (41) is rotatably connected to the housing (2), the powder scraping ring (41) is provided with a second gear (432), and the first gear (431) is meshed with the second gear (432).

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