Large-specification thick-wall insulation layer physical foaming radio frequency coaxial cable and manufacturing method thereof

Abstract

The invention relates to the technical field of radio-frequency coaxial cables, in particular to a large-specification thick-wall insulating layer physical foaming radio-frequency coaxial cable and a manufacturing method thereof.The foaming insulating layer is made of crosslinked polyethylene, the melt strength of the crosslinked polyethylene is high, and foam holes formed in the high-temperature foaming process are small in size and have the advantages of being uniform and compact; therefore, a foaming insulating layer which has a large wall thickness and is not easy to generate large bubbles can be formed. And meanwhile, the uniformity of bubbles in the foaming insulating layer is further ensured by utilizing a step-by-step cooling mode. Besides, the foaming insulation layer adopts a vertical production mode, the problems of foaming holes, hole stringing, out-of-round, eccentricity and the like caused by gravity in the horizontal production process of the foaming insulation layer are avoided, meanwhile, due to the vertical production mode, the foaming insulation layer is still kept in a circular ring shape and moves downwards along with traction of the conductor during extrusion, the roundness of the foaming insulation layer is kept, and the production efficiency is improved. And the attenuation performance of the product is further ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency coaxial cables, and in particular to a large-size thick-wall insulation layer physically foamed radio frequency coaxial cable and a manufacturing method thereof. Background Art

[0002] The principle of coaxial cable signal transmission is to use the interaction of electric and magnetic fields between the center conductor and the shield conductor to transmit signals. The insulation layer and shielding layer play a protective and shielding role to ensure the transmission quality of the signal.

[0003] Attenuation performance is one of the important parameters of RF coaxial cable. The lower the attenuation loss of coaxial cable, the better. Smaller transmission loss means less signal attenuation during transmission, which can maintain higher signal quality and reliability. According to the calculation formula of attenuation constant in national standards:

[0004] It can be seen that the attenuation constant determines the actual length of the project. Under the same material conditions, the attenuation performance depends on the amount of gas in the insulation layer. The larger the gas occupancy, the better the attenuation performance of the cable, and vice versa. Due to the limitations of production equipment and technical conditions, when the foaming degree is high or the insulation layer is thick, the insulation layer may collapse due to excessive or uneven pores in the insulation layer. Some manufacturers have proposed a double-layer insulation process, but in actual operation, the first layer of insulation foam is prone to contamination, resulting in uneven pores, which deteriorates the overall electrical performance of the cable. Currently, large-sized RF coaxial cables on the market cannot achieve thicker insulation layers. Summary of the invention

[0005] 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 large-size thick-walled insulating layer physical foamed radio frequency coaxial cable and a manufacturing method thereof. The product of the present invention redesigns the structure and improves the production process, specifically reducing the size of the inner conductor structure, thereby leaving space for the insulating layer. The 800MHz attenuation performance reaches 1.95dB / 100m, which is much better than similar products. Due to its excellent performance, this product has been recognized by domestic and foreign customers, and has been put into mass production, filling the domestic gap.

[0006] The technical solution adopted by the present invention to solve the technical problem is: A method for manufacturing a large-size thick-wall insulation layer physical foaming radio frequency coaxial cable comprises the following steps: Step 1, raw material testing: including testing the copper strip of the inner conductor and the copper strip of the outer conductor; Step 2, manufacturing the inner conductor: the copper strip of the inner conductor detected in step 1 is unrolled through a first unrolling rack, the surface of the copper strip of the inner conductor is cleaned, the cleaned copper strip of the inner conductor is finely cut to make the width of the copper strip of the inner conductor uniform, the finely cut copper strip of the inner conductor is formed, the formed copper strip of the inner conductor 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 inner conductor, the copper tube inner conductor is rounded, and after rounding, the outer surface of the copper tube inner conductor is corrugated, and the outer surface of the copper tube inner conductor is rolled into a spirally corrugated inner conductor with spiral grooves; Step 3, extruding the inner skin layer: the inner skin layer is coated on the outer surface of the inner conductor in step 2, the inner conductor in step 2 is unwound through a pay-off frame, the inner conductor is straightened, the straightened inner conductor is drawn and cleaned, the inner skin layer is heated by low-density polyethylene, the inner skin layer is uniformly extruded and coated on the outer surface of the inner conductor after drawing and cleaning, the inner skin layer is also vacuumed when being extruded and coated on the outer surface of the inner conductor, the inner skin layer is in close contact with the inner conductor, and 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; Step 4, extruding 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 in step 3, 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 percentages of the high-density polyethylene, the low-density polyethylene and the nucleating agent are 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent respectively, the foaming degree is 65-75%, the insulation outer diameter is 42.7±0.40mm, the foamed insulation layer is arranged in the vertical direction during the extrusion process, and after the foamed insulation layer is extruded, it passes through the cooling device in the vertical direction, and the cooling device adopts a step-by-step cooling method, and the high-density polyethylene and the low-density polyethylene are cross-linked polyethylene; Step 5: Production of the outer conductor: the copper strip of the outer conductor detected in the step 1 is unwound by a second unwinding rack, the surface of the copper strip of the outer conductor is cleaned, the cleaned copper strip of the outer conductor is finely cut to make the width of the copper strip of the outer conductor uniform, the finely cut copper strip of the outer conductor is formed, the formed copper strip of the outer conductor is formed into a round tube with the tube seam facing upward and closely connected, and then welded to form a closed and smooth copper tube outer conductor, the copper tube outer conductor is rounded, the inner conductor with the foamed insulation layer and the outer skin layer extruded in step 4 is placed in the copper tube outer conductor after rounding, and the outer surface of the copper tube outer conductor is corrugated to roll the outer surface of the copper tube outer conductor into an annular corrugated outer conductor with an annular groove; Step six: extruding the sheath: the material of the protective sheath is 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, the molten polyethylene sheath material or the low-smoke halogen-free flame-retardant polyolefin sheath material is extruded and coated on the outer surface of the outer conductor in step five, the sheath is also vacuumed when it is extruded and coated on the outer surface of the outer conductor, the sheath is made after it is in close contact with the outer surface of the outer conductor, and then cooled in a hot water tank with a temperature of 35°C, and then cooled in a cold water tank with normal temperature to make the sheath.

[0007] Through the above technical solution, the foamed insulation layer adopts cross-linked polyethylene. The cross-linked polyethylene has high melt strength, and the pores formed during the high-temperature foaming process are small in size and have the characteristics of uniformity and density. Therefore, it can form a foamed insulation layer with a large wall thickness and not easy to produce large bubbles. At the same time, the uniformity of the bubbles in the foamed insulation layer is further guaranteed by the step-by-step cooling method. In addition, the foamed insulation layer adopts a vertical production method to avoid the problems of pores, string holes, loss of roundness, eccentricity, etc. caused by gravity during the horizontal production process of the foamed insulation layer. At the same time, the vertical production method maintains the circular shape of the foamed insulation layer during extrusion and moves downward with the traction of the conductor, thereby maintaining the roundness of the foamed insulation layer, thereby ensuring the attenuation performance of the product.

[0008] Furthermore, in the step 2, embossing is performed by a corrugating blade on a corrugating device, the inner hole diameter of the corrugating blade is 12.90 mm, and it is rolled into a right direction. The welding die is 11.05 mm, and the rounding die is 11.00 mm, and a spirally corrugated inner conductor with a spiral groove is rolled.

[0009] Furthermore, in the step four: high-density polyethylene, low-density polyethylene and nucleating agent are weighed according to a ratio, and heated to a molten state to form a molten insulator, the gas is injected into the molten insulator, and kneaded to form a supersaturated gas-material mixture, the gas-material mixture is extruded and coated on the surface of the inner skin layer to form a foamed insulation layer, and at the same time, the outer skin layer is made of polyethylene material, the polyethylene is heated, and the heated polyethylene is extruded and coated on the foamed insulation layer to form an outer skin layer, which is then cooled by air and then by water for gradient cooling to ensure that the formed insulation layer is crystallized, and finally blown dry.

[0010] Furthermore, the purity of the gas in step 4 is 99.99%, and the gas is a mixture of CO2 and C4F8, or a mixture of N2 and C4F8. The gas is in liquid form before being injected into the molten insulator, and is gasified at high temperature to form a gaseous gas after being injected into the molten insulator.

[0011] A large-size thick-wall insulation layer physical foaming radio frequency coaxial cable is manufactured by the above manufacturing method, comprising an inner conductor, an inner skin layer, a foaming insulation layer, an outer skin layer, an outer conductor and a sheath arranged in sequence from the inside to the outside; the inner conductor is a spirally corrugated inner conductor with spiral grooves on the surface, and the outer conductor is an annularly corrugated outer conductor with annular grooves; the inner surface of the inner skin layer is threaded to fit with the outer surface of the inner conductor; the inner surface of the sheath has an annular protrusion to fit with the outer conductor.

[0012] The present invention discloses a large-size thick-walled insulating layer physically foamed radio frequency coaxial cable. Generally, the larger the cable is, the worse its bending performance is. The inner conductor adopts a spiral wrinkle with spiral grooves on the surface, which can play a role similar to a spring structure. The ductility of the inner conductor is utilized to improve the overall toughness of the cable, thereby greatly improving the bending ability of the product. The annular wrinkle outer conductor with annular grooves can adapt to bending through its annular grooves, thereby further improving the bending ability of the cable product. At the same time, the fitting of the inner skin layer and the sheath layer can provide strong support for the inner conductor and the outer conductor, thereby further ensuring the bending performance of the cable product.

[0013] Furthermore, the width of the copper strip of the inner conductor is smaller than the width of the copper strip of the outer conductor, and the thickness of the copper strip of the inner conductor and the thickness of the copper strip of the outer conductor are both 0.10 mm to 0.35 mm.

[0014] Furthermore, 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 ratio of the high-density polyethylene, the low-density polyethylene and the nucleating agent are 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent respectively, and the foaming degree is 65-75%.

[0015] Furthermore, the thickness of the inner skin layer is 0.03-0.1 mm, and the thickness of the outer skin layer is 0.05-0.1 mm.

[0016] Furthermore, the foamed insulation layer is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and a gas.

[0017] Furthermore, the gas is a mixture of CO2 and C4F8, or a mixture of N2 and C4F8, and the fully closed pore foaming degree is 60-70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 The present invention is a schematic structural diagram of a large-size thick-wall insulation layer physically foamed radio frequency coaxial cable.

[0020] Figure 2 The present invention is a schematic flow chart of a method for manufacturing a large-size thick-wall insulation layer physical foaming radio frequency coaxial cable.

[0021] In the figure: 1. inner conductor; 2. inner skin layer; 3. foam insulation layer; 4. outer skin layer; 5. outer conductor; 6. sheath. DETAILED DESCRIPTION

[0022] 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.

[0023] 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.

[0024] The invention discloses a large-size thick-wall insulation layer physical foaming radio frequency coaxial cable and a manufacturing method thereof.

[0025] Reference Figure 1 A large-size thick-wall insulation layer physical foaming radio frequency coaxial cable includes an inner conductor 1, an inner skin layer 2, a foaming insulation layer 3, an outer skin layer 4, an outer conductor 5 and a sheath 6 which are arranged in sequence from the inside to the outside; the inner conductor 1 is a spirally corrugated inner conductor 1 with spiral grooves on the surface, and the outer conductor 5 is an annularly corrugated outer conductor 5 with annular grooves; the inner surface of the inner skin layer 2 is threaded to fit with the outer surface of the inner conductor 1; the inner surface of the sheath 6 has an annular protrusion to fit with the outer conductor 5.

[0026] The copper tape width of the inner conductor 1 is smaller than that of the outer conductor 5, and the copper tape thickness of the inner conductor 1 and the copper tape thickness of the outer conductor 5 are both 0.10 mm to 0.35 mm. The thickness of the inner skin layer 2 is 0.03 mm to 0.1 mm, and the thickness of the outer skin layer 4 is 0.05 mm to 0.1 mm.

[0027] The foamed insulating layer 3 is an insulating 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, and the foaming degree is 60-70%. The gas is a mixture of CO2 and C4F88, or a mixture of N2 and C4F8, and the fully closed pore foaming degree is 65-75%.

[0028] A manufacturing method, based on the above-mentioned large-size thick-wall insulation layer physical foaming radio frequency coaxial cable, referring to Figure 2 , including the following steps: Step 1: raw material testing: including testing the copper strip of the inner conductor 1 and the copper strip of the outer conductor 5 .

[0029] Step 2, making the inner conductor 1: the copper strip of the inner conductor 1 inspected in step 1 is unrolled through a first unrolling rack, the surface of the copper strip of the inner conductor 1 is cleaned, the cleaned copper strip of the inner conductor 1 is fine-cut to make the width of the copper strip of the inner conductor 1 uniform, the fine-cut copper strip of the inner conductor 1 is formed, the formed copper strip of the inner conductor 1 forms a rounded tube with the tube seam facing upward and tightly connected, and then is welded to form a closed and smooth copper tube inner conductor 1, the copper tube inner conductor 1 is rounded, and after rounding, the outer surface of the copper tube inner conductor 1 is corrugated, and the outer surface of the copper tube inner conductor 1 is rolled into a spirally corrugated inner conductor 1 with spiral grooves.

[0030] During corrugation, the corrugation is performed by the corrugating blade on the corrugating equipment. The inner hole diameter of the corrugating blade is 12.90 mm, and it is rolled into the right direction. The inner hole size of the welding die is 11.05 mm, and the inner hole size of the rounding die is 11.00 mm, rolling into a spirally corrugated inner conductor 1 with a spiral groove.

[0031] Step 3, extruding the inner cortex 2: the inner conductor 1 in step 2 is coated with the inner cortex 2, the inner conductor 1 in step 2 is unwound on a pay-off frame, the inner conductor 1 is straightened, the straightened inner conductor 1 is drawn and cleaned, the inner cortex 2 is heated by low-density polyethylene, the inner cortex 2 is uniformly extruded and coated on the outer surface of the inner conductor 1 after drawing and cleaning, and the inner cortex 2 is also vacuumed when being extruded and coated on the outer surface of the inner conductor 1, so that the inner cortex 2 is in close contact with the inner conductor 1, and after the inner cortex 2 is extruded and coated on the outer surface of the inner conductor 1, the inner conductor 1 extruded with the inner cortex 2 is cooled; Step 4, extruding a foamed insulation layer 3 and an outer skin layer 4: the inner skin layer 2 in step 3 is coated with a foamed insulation layer 3 and an outer skin layer 4, the foamed insulation layer 3 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 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 60-70%, and the insulation outer diameter is 42.7±0.40mm.

[0032] High-density polyethylene, low-density polyethylene and nucleating agent are weighed according to the proportion and heated to a molten state to form a molten insulator. Gas is injected into the molten insulator and mixed to form a supersaturated gas-material mixture. The purity of the gas is 99.99%. The gas is a mixture of CO2 and C4F8, or a mixture of N2 and C4F8. The gas is in liquid form before being injected into the molten insulator. After being injected into the molten insulator, it is gasified at high temperature to form a gaseous gas. The gas-material mixture is extruded and coated on the surface of the inner skin layer 2 to form a foamed insulation layer 3. At the same time, the outer skin layer 4 is made of polyethylene material. The polyethylene is heated, and the heated polyethylene is extruded and coated on the foamed insulation layer 3 to form the outer skin layer 4. Then, it is cooled by air and then cooled by water for gradient cooling to ensure that the formed insulation layer is crystallized, and finally blown dry.

[0033] Both high-density polyethylene and low-density polyethylene are cross-linked polyethylene, and the cross-linked polyethylene can be a cross-linked foamed polyethylene product produced by China General Nuclear Power Delta (Jiangsu) Plastics Co., Ltd., or the patent number CN112358673A applied by the company can be referred to. The cross-linked polyethylene has high melt strength, and the pore size formed during the high-temperature foaming process is small and has the characteristics of uniform density, so it can form a foamed insulation layer 3 with a large wall thickness and is not easy to generate large bubbles.

[0034] The foamed insulation layer 3 is arranged in the vertical direction during the extrusion process, and after the foamed insulation layer 3 is extruded, it passes through the cooling device in the vertical direction. The cooling device includes a steam zone and a cooling water trough zone. The temperature of the steam zone can be 70 degrees Celsius, and the water temperature in the cooling water trough can be 30 to 45 degrees Celsius. Multiple cooling water troughs can be set, and the temperature is reduced one by one. When the foamed insulation layer 3 passes through the steam zone, cross-linking occurs and begins to solidify. The cooling water trough further improves the curing efficiency. At the same time, through the step-by-step cooling method, the possibility of large bubbles in the foamed insulation layer 3 due to excessive cooling is reduced.

[0035] In addition, since the foamed insulation layer 3 adopts a vertical production method, the problems of foam holes, string holes, out-of-round eccentricity, etc. caused by gravity in the horizontal production process of the foamed insulation layer are avoided. At the same time, the vertical production method further ensures the roundness of the foamed insulation layer 3 because the foamed insulation layer still maintains a circular shape during extrusion and moves downward with the traction of the conductor.

[0036] Step 5: making the outer conductor 5: putting the copper strip of the outer conductor 5 detected in step 1 through the second unwinding rack, cleaning the surface of the copper strip of the outer conductor 5, and fine-cutting the cleaned copper strip of the outer conductor 5 to make the width of the copper strip of the outer conductor 5 uniform. The finely cut copper strip of the outer conductor 5 is formed, and the formed copper strip of the outer conductor 5 is formed into a round tube with the tube seam facing upward and closely connected, and then welded to form a closed and smooth copper tube outer conductor 5, and the copper tube outer conductor 5 is rounded, and the inner conductor 1 extruded with the foamed insulation layer 3 and the outer skin layer 4 in step 4 is placed in the copper tube outer conductor 5 after rounding, and the outer surface of the copper tube outer conductor 5 is corrugated, and the outer surface of the copper tube outer conductor 5 is rolled into an annular corrugated outer conductor 5 with an annular groove; Step six: extruded sheath 6: the material of the protective sheath 6 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 molten polyethylene sheath 6 material or low-smoke halogen-free flame-retardant polyolefin sheath 6 material is extruded and coated on the outer surface of the outer conductor 5 in step five, the sheath 6 is also vacuumed when it is extruded and coated on the outer surface of the outer conductor 5, the sheath 6 is made after it is in close contact with the outer surface of the outer conductor 5, and then cooled in a hot water tank with a temperature of 35°C, and then cooled in a cold water tank with normal temperature to make the sheath 6.

[0037] Table 1 below is the statistical data after the attenuation performance test:

[0038] Table 1 It can be seen from the data that the attenuation performance of the large-size thick-wall insulation layer physical foamed radio frequency coaxial cable of the present application is better than similar products on the market.

[0039] 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 method for manufacturing a large-size thick-wall insulation layer physical foaming radio frequency coaxial cable, characterized in that: The steps include: Step 1: raw material testing: testing the copper strip of the inner conductor (1) and the copper strip of the outer conductor (5); Step 2, manufacturing the inner conductor (1): the copper strip of the inner conductor (1) inspected in step 1 is unrolled through a first unrolling rack, the surface of the copper strip of the inner conductor (1) is cleaned, the cleaned copper strip of the inner conductor (1) is finely cut to make the width of the copper strip of the inner conductor (1) uniform, the finely cut copper strip of the inner conductor (1) is formed, the formed copper strip of the inner conductor (1) is formed into a round tube with the seam facing upward and tightly connected, and then welded to form a closed and smooth copper tube inner conductor (1), the copper tube inner conductor (1) is rounded, and after rounding, the outer surface of the copper tube inner conductor (1) is corrugated, and the outer surface of the copper tube inner conductor (1) is rolled into a spiral corrugated inner conductor (1) with spiral grooves; Step 3, extruding an inner cortex (2): the inner conductor (1) of step 2 is coated with an inner cortex (2), the inner conductor (1) of step 2 is unwound through a pay-off frame, the inner conductor (1) is straightened, the straightened inner conductor (1) is drawn and cleaned, the inner cortex (2) is heated using low-density polyethylene, the inner cortex (2) is uniformly extruded and coated on the outer surface of the inner conductor (1) after drawing and cleaning, and the inner cortex (2) is vacuumed when being extruded and coated on the outer surface of the inner conductor (1), so that the inner cortex (2) is in close contact with the inner conductor (1), and after the inner cortex (2) is extruded and coated on the outer surface of the inner conductor (1), the inner conductor (1) extruded with the inner cortex (2) is cooled; Step 4, extruding a foamed insulation layer (3) and an outer skin layer (4): the inner skin layer (2) of step 3 is coated with a foamed insulation layer (3) and an outer skin layer (4), the foamed insulation layer (3) 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 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%, the insulation outer diameter is 42.7±0.40mm, the foamed insulation layer (3) is arranged in the vertical direction during the extrusion process, and after the foamed insulation layer (3) is extruded, it passes through a cooling device in the vertical direction, and the cooling device adopts a step-by-step cooling method, and the high-density polyethylene and the low-density polyethylene are both cross-linked polyethylene; Step 5: making the outer conductor (5): the copper strip of the outer conductor (5) tested in step 1 is unwound by a second unwound rack, the surface of the copper strip of the outer conductor (5) is cleaned, the cleaned copper strip of the outer conductor (5) is finely cut to make the width of the copper strip of the outer conductor (5) uniform, the finely cut copper strip of the outer conductor (5) is molded, the copper strip of the molded outer conductor (5) is formed into a round tube with the tube seam facing upward and tightly connected, and then welded to form a closed and smooth copper tube outer conductor (5), the copper tube outer conductor (5) is rounded, the inner conductor (1) with the extruded foam insulation layer (3) and the outer skin layer (4) in step 4 is placed in the copper tube outer conductor (5) after rounding, and the outer surface of the copper tube outer conductor (5) is corrugated, and the outer surface of the copper tube outer conductor (5) is rolled into an annular corrugated outer conductor (5) with an annular groove; Step 6: Extruding the sheath (6): The sheath (6) is made of 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 molten polyethylene sheath (6) material or low-smoke halogen-free flame-retardant polyolefin sheath (6) material is extruded and coated on the outer surface of the outer conductor (5) in step 5. When the sheath (6) is extruded and coated on the outer surface of the outer conductor (5), a vacuum treatment is also performed. After the sheath (6) is in close contact with the outer surface of the outer conductor (5), the sheath (6) is completed. It is 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 form the sheath (6).

2. The method according to claim 1, characterized in that: In the step 2, corrugation is performed by an embossing blade on a corrugating device, wherein the inner hole diameter of the embossing blade is 12.90 mm and the conductor is rolled to the right. The welding die is 11.05 mm and the rounding die is 11.00 mm, and a spirally corrugated inner conductor (1) with spiral grooves is rolled.

3. The method according to claim 2, characterized in that: In the step 4: high-density polyethylene, low-density polyethylene and a nucleating agent are weighed according to a ratio and heated to a molten state to form a molten insulator, the gas is injected into the molten insulator, and the mixture is kneaded to form a supersaturated gas-material mixture, the gas-material mixture is extruded and coated on the surface of the inner skin layer (2) to form a foamed insulation layer (3), and at the same time, the outer skin layer (4) is made of polyethylene material, the polyethylene is heated, and the heated polyethylene is extruded and coated on the foamed insulation layer (3) to form the outer skin layer (4), and then air-cooled and water-cooled for gradient cooling to ensure that the formed insulation layer is crystallized, and finally blow-dried.

4. The method for manufacturing a large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 3, characterized in that: The purity of the gas in step 4 is 99.99%. The gas is a mixture of CO2 and C4F8, or a mixture of N2 and C4F8. The gas is in liquid form before being injected into the molten insulator, and is gasified at high temperature to form a gaseous gas after being injected into the molten insulator.

5. A large-size thick-walled insulating layer physically foamed radio frequency coaxial cable, manufactured by the manufacturing method of a large-size thick-walled insulating layer physically foamed radio frequency coaxial cable according to any one of claims 1 to 4, characterized in that: It comprises an inner conductor (1), an inner skin layer (2), a foamed insulating layer (3), an outer skin layer (4), an outer conductor (5) and a sheath (6) which are arranged in sequence from the inside to the outside; The inner conductor (1) is a spirally corrugated inner conductor (1) having a spiral groove on its surface, and the outer conductor (5) is an annularly corrugated outer conductor (5) having an annular groove; The inner surface of the inner skin layer (2) is threaded so as to fit with the outer surface of the inner conductor (1); the inner surface of the sheath (6) has an annular protrusion so as to fit with the outer conductor (5).

6. The large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 5 is characterized in that: The width of the copper tape of the inner conductor (1) is smaller than the width of the copper tape of the outer conductor (5), and the thickness of the copper tape of the inner conductor (1) and the thickness of the copper tape of the outer conductor (5) are both 0.10 mm to 0.35 mm.

7. The large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 5 is characterized in that: The foamed insulation layer (3) is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and gas, wherein the polyethylene comprises high-density polyethylene and low-density polyethylene, and the weight percentages of the high-density polyethylene, the low-density polyethylene and the nucleating agent are respectively 45% high-density polyethylene, 51% low-density polyethylene and 4% nucleating agent, and the foaming degree is 65-75%.

8. The large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 5, characterized in that: The thickness of the inner skin layer (2) is 0.03 to 0.1 mm, and the thickness of the outer skin layer (4) is 0.05 to 0.1 mm.

9. The large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 5, characterized in that: The foamed insulation layer (3) is an insulation layer formed by physical foaming of polyethylene, a nucleating agent and a gas.

10. The large-size thick-wall insulation layer physical foaming radio frequency coaxial cable according to claim 5, characterized in that: 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%.

Images