Airtight armor low-loss radio frequency cable and manufacturing method thereof

Abstract

The invention relates to the technical field of cable assemblies, and provides an airtight armor low-loss radio frequency cable and a manufacturing method thereof. The cable comprises a low-loss radio frequency cable body serving as a trunk, and the two ends of the low-loss radio frequency cable body are connected with connectors used for connecting a cable assembly with the outside; the manufacturing method comprises the steps that a low-loss radio frequency cable is adopted as a trunk of the cable assembly, a polyimide insulating layer and a multi-layer microporous film are wrapped outside a wire core in the low-loss radio frequency cable, and the low-loss radio frequency cable is formed through combination; according to the invention, the low-loss radio frequency cable is adopted, and the polyimide insulating material is wrapped outside the cable, so that the power resistance and the average service power of the cable are improved. Meanwhile, the low-loss radio frequency cable reduces standing waves and loss, and ensures stable transmission and reliability. Silicone rubber is coated between the armor corrugated pipe and the connector, and the armor corrugated pipe and the connector are connected through the pressing sleeve, so that the air tightness of the cable assembly and the reliability of the joint are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of cable components, and more specifically, to an airtight armored low-loss radio frequency cable and a manufacturing method thereof. Background Art

[0002] With the rapid development of my country's communications industry, the technical indicators of the supporting electronic components are getting higher and higher. Cable components are not only required to have low standing wave, low loss, good stability, and excellent shielding performance;

[0003] Cable assemblies are an integral structure assembled from cables and their related connectors, joints, plugs, sockets and other components, usually used to transmit electrical signals or electrical energy. The main types include power cable assemblies for transmitting high-current power systems, signal cable assemblies for transmitting data or low-current signals, optical fiber cable assemblies for high-speed data transmission, and high-frequency cable assemblies for radio frequency signal transmission.

[0004] However, for special applications with relatively large working power, long duration, and in the wild, the mechanical strength and airtightness requirements of the cable assembly need to be considered;

[0005] In order to solve the above problems, the present application proposes an airtight armored low-loss radio frequency cable and a manufacturing method thereof. Summary of the invention

[0006] The object of the present invention is to provide an airtight armored low-loss radio frequency cable and a manufacturing method thereof, which ensures airtightness while ensuring the strength of the cable assembly.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] An airtight armored low-loss radio frequency cable comprises a low-loss radio frequency cable as a trunk, both ends of the low-loss radio frequency cable are connected with connectors for connecting a cable assembly to the outside, the outer sleeve of the low-loss radio frequency cable not connected to the connector is provided with an armored bellows for improving wear resistance, both ends of the low-loss radio frequency cable and the armored bellows are welded and fixed to the connector, the outer portion of the armored bellows connected to the connector is provided with a compression sleeve for improving airtightness, the outer portion of the connection between the connector and the armored bellows is also provided with a double-walled tube with glue to cover the compression sleeve to ensure airtightness, the outer portion of the connection between the connector, the armored bellows and the double-walled tube with glue is also provided with a transparent sleeve, and the cable assembly is airtight inside and outside; the outer portion of the wire core in the low-loss radio frequency cable is wrapped with a layer of polyimide insulation.

[0009] In the above technical solution, the cable air seal is not only waterproof and moisture-proof, but also can avoid failures caused by gas leakage or pressure changes inside the cable. Especially in some industrial occasions that require strict control of the atmosphere, air sealing can ensure the stability and safety of the cable system and prevent safety hazards such as electrical fires or short circuits caused by changes in air pressure or atmosphere; in some special environments, such as high-pressure areas such as deep sea and underground, air sealing technology can enhance the pressure resistance of the cable and prevent the cable from being damaged due to excessive external pressure. Air sealing can ensure that the cable will not be invaded by moisture or external gas in a high-pressure environment, protecting the cable from damage; by preventing the invasion of moisture, air and pollutants, air sealing can effectively improve the overall reliability and stability of the cable. In critical infrastructure (such as communications, electricity, petrochemical and other industries), the high reliability of the cable is the key to ensuring the normal operation of the system.

[0010] The armor corrugated tube is extruded with a polyurethane protective sleeve on the outside, with a thickness of 0.5 to 0.55 mm;

[0011] In the above technical solution, for the armored corrugated pipe, coating the outer polyurethane sheath can enhance its compression resistance and bending resistance, thereby extending the service life of the pipe, especially in occasions where it needs to withstand high pressure or harsh environment.

[0012] The armored corrugated tube is provided with a marking sleeve from the side, and the marking sleeve is provided in two pieces and is close to the connector;

[0013] In the above technical solution, by using the indications on the marking sleeve, the staff can quickly locate the direction and distribution position of the cable, especially in a complex power distribution system, which can reduce the time of finding the fault point and improve the maintenance efficiency.

[0014] The identification sleeve is a heat shrink structure and is provided with an identification plate directly above it. The mark on the identification plate on the same side faces the connector on the corresponding side. The distance between the identification sleeve and the connector is between 150-250 mm.

[0015] In the above technical solution, the identification plate in the identification sleeve can also mark key information such as the type, purpose, voltage level, etc. of the cable, so that the staff can quickly identify the characteristics of the cable during operation and maintenance, thereby avoiding misoperation or dangerous contact.

[0016] The polyimide is externally wrapped with several layers of microporous membranes, and the low-loss radio frequency cable is electrically connected to the connector;

[0017] In the above technical solution, the microporous membrane reduces the density of the medium, and the cable toughness and anti-aging performance are better. It also has the advantages of breathable and waterproof, high strength, chemical stability and good electrical insulation.

[0018] The connector, the connection of the armor bellows and the external connection of the connector are all coated with silicone rubber to ensure airtightness;

[0019] In the above technical solution, silicone rubber can not only play the role of connection sealing, but also has excellent insulation, high temperature resistance, weather resistance, flexibility, corrosion resistance and waterproof and moisture-proof properties, and can ensure sealing reliability even in high temperature, harsh environment or special needs.

[0020] The double-walled tube with adhesive is heat-shrunk and attached to the connection between the connector and the armored corrugated tube, and the identification sleeve is heat-shrunk and attached to the outside of the armored corrugated tube. After the transparent sleeve is heat-shrunk, the connector, the armored corrugated tube, the double-walled tube with adhesive, and the identification sleeve are sealed at the same time;

[0021] In the above technical solution, the heat shrink tube is tightly wrapped around the surface of the cable by heat shrinkage, providing the cable with multiple functions such as electrical insulation protection, mechanical protection, waterproof and moisture-proof, UV protection, and chemical corrosion resistance, thereby improving the performance and service life of the cable.

[0022] The purpose of the present invention can also be achieved by the following technical solutions:

[0023] A method for manufacturing an airtight armored low-loss radio frequency cable, the steps are as follows:

[0024] S1. A low-loss RF cable is used as the backbone of the cable assembly. A layer of polyimide insulation layer and a multi-layer microporous film are respectively wrapped around the outer surface of the wire core of the low-loss RF cable to form a low-loss RF cable;

[0025] S2. An armored corrugated tube is sheathed on the outside of the low-loss RF cable, and a polyurethane sheath is pre-extruded on the outside of the armored corrugated tube;

[0026] S3. Insert the identification sleeve, transparent sleeve and double-walled tube with adhesive into both ends of the armored corrugated tube in sequence. The identification plate on the identification sleeve has a logo pointing to the connector;

[0027] S4. Pre-pierce the components of the connector in sequence, and connect the tail of the connector to the end of the armor bellows;

[0028] S5. Weld the conductors, assemble the connectors, and apply silicone rubber to the threads on the connectors to make them tightly connected to the external connectors;

[0029] S6. Use a compression sleeve to press the connection between the connector and the armored bellows, and evenly apply silicone rubber to the connection between the connector and the armored bellows, and then attach the heat shrink tape double-wall tube to the connection between the connector and the armored bellows;

[0030] S7. Carry out an airtight test. If it passes the test, heat shrink the identification sleeve on the outside of the armor bellows. Finally, heat shrink the transparent sleeve on the outside of the connector, armor bellows, double-walled tube with glue, and identification sleeve.

[0031] In the above technical solution, the cable air seal can effectively prevent water and moisture from penetrating into the interior of the cable, especially in high humidity environments or underwater applications. The air seal can effectively prevent dust, sand, chemicals or other pollutants from entering the interior of the cable. This is especially important for cables in complex environments such as industry, mining, and transportation. Since the air seal can prevent the intrusion of water, oxygen and pollutants, it can effectively slow down the aging of the cable and extend the service life of the cable.

[0032] The ends of the low-loss radio frequency cable and the armored corrugated tube are both provided with connectors and are sealed and fixed;

[0033] In the above technical solution, the main purpose of cable gas sealing is to ensure the safety, reliability and adaptability of the cable to various complex environments. Its benefits are that it can effectively improve the performance of the cable during use and avoid the influence of the external environment on the inside of the cable. The specific advantages are waterproof and moisture-proof, prevent the intrusion of pollutants, increase the service life of the cable, prevent corrosion, improve the safety of the cable, enhance the pressure resistance, and avoid gas leakage inside the cable.

[0034] The thickness of the polyurethane sheath outside the armor corrugated tube is between 0.5 and 0.55 mm, and the distance between the marking sleeve and the connector after heat shrinkage is 200 mm;

[0035] In the above technical scheme, the polyurethane sheath has strong mechanical strength and can effectively protect the corrugated pipe from external impact, friction, pulling and other external forces. At the same time, the polyurethane material also has strong wear resistance, high corrosion resistance, good weather resistance, excellent elasticity and impact resistance, waterproof and moisture-proof, light and beautiful, UV resistance, and aging resistance.

[0036] Beneficial effects of the present invention:

[0037] The present invention uses a low-loss radio frequency cable as a connection, and wraps a layer of polyimide insulation material around the outside of the wire core, thereby increasing the cable's withstand power and thus improving the average power usage;

[0038] The low-loss RF cable used can reduce standing waves in the components and reduce losses, while ensuring stable transmission and improving the reliability of cable components.

[0039] Silicone rubber is applied between the armored corrugated tube and the connector and then connected externally through a compression sleeve. Silicone rubber is also applied to the connection between the connector and the outside. At the same time, the double-walled tube with glue and the transparent sleeve ensure the air tightness of the cable assembly, the reliability of the cable assembly and the connection, and the durability is also improved;

[0040] The low-loss RF cable is protected by an armored corrugated tube installed on the outside, which improves its wear resistance and abrasion resistance and has high mechanical strength. Even if the cable has a right-angle bend when it is used in the pipe, it can be used stably and reliably, ensuring that the cable assembly will not cause irreversible damage to the bending point when it is bent. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 It is a structural schematic diagram of the present invention;

[0043] Figure 2 for Figure 1 Schematic diagram of the structure when the transparent sleeve is detached;

[0044] Figure 3 for Figure 1 A schematic diagram of the structure in partial half section from the main view;

[0045] Figure 4 It is a schematic diagram of the structure of a half-section of a low-loss radio frequency cable;

[0046] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0047] In the figure: 1. low-loss RF cable; 101. wire core; 102. polyimide; 103. microporous membrane; 2. connector; 3. armored corrugated tube; 4. compression sleeve; 5. double-walled tube with glue; 6. identification sleeve; 601. identification plate; 7. transparent sleeve. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] like Figure 1 - Figure 4 As shown:

[0050] Example 1

[0051] The present embodiment provides an airtight armored low-loss RF cable, wherein the low-loss RF cable 1 contains a plurality of RF cable cores 101 for high-frequency signal transmission, and the cores 101 of the low-loss RF cable 1 are wrapped with a layer of polyimide 102 insulation layer on the outside. In order to further improve the insulation performance and signal transmission efficiency of the cable, several layers of microporous membrane 103 are also wrapped around the outside of the polyimide insulation layer 102. The microporous membrane 103 plays a role in shielding and isolating external interference signals, effectively improving the anti-interference ability of the cable. The low-loss RF cable 1 has good low-loss characteristics and is suitable for high-frequency signal transmission. The outside of the RF cable uses a reinforced armor bellows 3 to improve its wear resistance and protective performance. The connector 2 is installed at both ends of the low-loss RF cable 1 and is connected to the low-loss RF cable 1 and the armor bellows 3 by welding and fixing, ensuring that the cable can be reliably connected to external equipment;

[0052] In this embodiment, the airtight armored low-loss RF cable adopts a multi-layer protection structure to improve the durability and airtightness of the cable, and is suitable for use in high-frequency and harsh environments. The design of the armored corrugated tube and the polyurethane protective sleeve provides good mechanical protection, while the use of silicone rubber seals, compression sleeves and double-walled tubes with glue effectively prevents gas and moisture from entering the cable, ensuring the long-term stable operation of the cable; in addition, the design of the transparent sleeve and identification sleeve facilitates the identification and detection of the cable during installation and maintenance, improving the convenience of use.

[0053] As an embodiment of the present invention, a polyurethane protective sleeve with a thickness of about 0.5 to 0.55 mm is formed on the outside of the armored corrugated tube 3 by an extrusion process, thereby enhancing the wear resistance and impact resistance of the cable. In addition, an identification sleeve 6 is provided on the outside of the armored corrugated tube. The identification sleeve 6 adopts a heat shrink structure to facilitate the identification and positioning of the cable during installation. The mark on the identification sleeve 6 is located near the connector 2, and the distance from the connector 2 is 150 mm to 250 m;

[0054] As an embodiment of the present invention, in order to ensure the air tightness of the cable assembly, a compression sleeve 4 is provided outside the connection portion between the connector 2 and the armored corrugated tube 3, and the compression sleeve 4 improves the air tightness of the connection portion by tightening. In order to further improve the sealing effect, silicone rubber is applied between the connector 2 and the armored corrugated tube 3 to ensure that the connection is airtight.

[0055] As an embodiment of the present invention, at the connection part between the armor bellows 3 and the compression sleeve 4, a double-walled tube 5 with adhesive is set on the outside. The double-walled tube 5 with adhesive is heat-shrunk and fitted at the connection part between the connector 2 and the armor bellows 3, further improving the sealing effect. The double-walled tube 5 with adhesive and the identification sleeve 6 outside the armor bellows 3 form an integrated structure through the heat shrink process.

[0056] As an embodiment of the present invention, the transparent sleeve 7 covers all connection parts, including the connector 2, the armored corrugated tube 3, the double-walled tube with glue 5 and the identification sleeve 6. The transparent sleeve 7 forms a sealing effect through heat shrinkage technology to ensure that the entire cable assembly is airtight inside and outside, preventing gas or moisture from the external environment from entering the cable, thereby ensuring that the cable can work stably for a long time in harsh environments.

[0057] This embodiment also provides a method for manufacturing an airtight armored low-loss radio frequency cable, the specific steps of which are as follows:

[0058] S1. Preparation of low-loss RF cables:

[0059] A low-loss radio frequency cable 1 is used as the backbone of the cable assembly. In the low-loss radio frequency cable 1, a layer of polyimide 102 insulation layer is wrapped around the core 101, and the outer layer is further wrapped with a multi-layer microporous film 103. This structure ensures low loss and excellent insulation performance of the cable.

[0060] S2. Installation of armor bellows:

[0061] An armored corrugated tube 3 is sheathed on the outside of the low-loss RF cable 1. The armored corrugated tube 3 is made of a metal corrugated tube material and has good mechanical protection performance. A layer of polyurethane sheath (thickness of 0.5-0.55 mm) is pre-extruded on the outside of the armored corrugated tube 3 to provide an additional protective layer and improve the wear resistance and mechanical strength of the cable.

[0062] S3. Design of marking sleeve and transparent sleeve:

[0063] At both ends of the armored corrugated tube 3, the identification sleeve 6, the transparent sleeve 7 and the double-walled tube with adhesive 5 are sequentially inserted. Among them, the identification sleeve 6 is provided with an identification plate 601 for marking the connection direction of the cable to ensure that the direction of the connector 2 can be correctly identified during installation. The identification sleeve 6 is a heat shrink structure, and it is ensured to fit tightly during installation.

[0064] S4. Pre-assembly of connectors:

[0065] Insert the components of the connector 2 in sequence, and connect the tail of the connector 2 to the end of the armored corrugated tube 3. The connector 2 is fixed to the end of the armored corrugated tube 3 by threaded connection to ensure reliable connection between the cable and the external device.

[0066] S5. Welding and assembling connectors:

[0067] The conductors on the connector 2 are welded and the connector 2 is assembled. After welding, silicone rubber is applied to the threads on the connector 2 to ensure sealing and airtightness and avoid signal interference and infiltration of foreign substances.

[0068] S6. Pressing sleeve and sealing treatment:

[0069] At the connection between the connector 2 and the armored corrugated tube 3, the connection is compressed with a compression sleeve 4 to ensure the firmness and airtightness of the connection. Next, silicone rubber is evenly applied to the connection, and then the double-walled tube 5 with adhesive is heat-shrink-fitted to the connection between the connector 2 and the armored corrugated tube 3 to further enhance the sealing effect.

[0070] S7. Airtightness test and final heat shrinkage:

[0071] An airtightness test is performed to ensure that the cable assembly is airtight inside and outside. After the test is qualified, the identification sleeve 6 and the transparent sleeve 7 are heat-shrunk and attached to the outside of the armored corrugated tube 3 to ensure the integrity of the cable assembly. The transparent sleeve 7 wraps the connector 2, the armored corrugated tube 3, the double-wall tube with glue 5 and the identification sleeve 6 to complete the final protection and sealing.

[0072] S8. Finished product inspection:

[0073] Finally, the finished product is inspected to ensure that the performance indicators of the cable meet the design requirements, including electrical performance, mechanical performance and air tightness. Qualified cables can be shipped and put into practical use.

[0074] In this embodiment:

[0075] The air tightness of the cable in the working environment is ensured by silicone rubber coating, the use of compression sleeves and heat shrinkage of double-walled tubes with glue;

[0076] Armored corrugated tube and polyurethane sheath provide good wear resistance and mechanical protection, increasing the service life of the cable;

[0077] The design of the identification sleeve and transparent sleeve facilitates the correct direction identification of the cable during installation and reduces installation errors;

[0078] The use of low-loss RF cables and their special insulation layer design ensures the low-loss performance of the cables in high-frequency signal transmission.

[0079] Through the manufacturing method of the above embodiment, an airtight, wear-resistant and low-loss RF cable can be produced, which is suitable for environments requiring high-performance signal transmission and strict sealing requirements, such as communication equipment, aerospace, military and other fields.

[0080] Example 2

[0081] This embodiment is based on the embodiment 1, and adopts armored corrugated tubes 3 of different specifications and connectors 2 of different sizes. In this case, the external protective material of the cable assembly is similar to that of the previous embodiment, but the specifications of the connector 2 are slightly adjusted to adapt to different signal transmission requirements and external environmental conditions.

[0082] In this embodiment, the identification sleeve 6 uses identifications of different colors to distinguish cable systems of different purposes, and is appropriately improved according to on-site requirements to improve installation efficiency.

[0083] These embodiments demonstrate how to improve cable performance, enhance durability, and ensure air tightness by optimizing the structural design of the cable according to different needs and environmental conditions.

[0084] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "around" and the like indicate orientation or positional relationship, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0085] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-loss radio frequency cable with airtight armor, characterized in that: It includes a low-loss radio frequency cable as a trunk, both ends of the low-loss radio frequency cable are connected with connectors for connecting the cable assembly to the outside, the outer sleeve of the low-loss radio frequency cable not connected to the connector is provided with an armored corrugated tube for improving wear resistance, both ends of the low-loss radio frequency cable and the armored corrugated tube are welded and fixed to the connector, the outer portion of the armored corrugated tube connected to the connector is provided with a compression sleeve for improving air tightness, the outer portion of the connection between the connector and the armored corrugated tube is also provided with a double-walled tube with glue to cover the compression sleeve to ensure air tightness, the outer portion of the connection between the connector, the armored corrugated tube and the double-walled tube with glue is also provided with a transparent sleeve, and the cable assembly is airtight inside and outside; The core of the low-loss radio frequency cable is wrapped with a polyimide insulation layer.

2. The airtight armored low-loss radio frequency cable according to claim 1, characterized in that: The armor corrugated tube is extruded with a polyurethane protective sleeve on the outside, and the thickness is between 0.5 and 0.55 mm.

3. The airtight armored low-loss radio frequency cable according to claim 1, characterized in that: The armor corrugated tube is sleeved with an identification sleeve from the side outside, and the identification sleeves are arranged in two and close to the connector.

4. The airtight armored low-loss radio frequency cable according to claim 3, characterized in that: The identification sleeve is a heat shrink structure and is provided with an identification plate directly on the top. The mark on the identification plate on the same side faces the connector on the corresponding side. The distance between the identification sleeve and the connector is between 150-250mm.

5. The airtight armored low-loss radio frequency cable according to claim 1, characterized in that: The polyimide is externally wrapped with several layers of microporous membranes, and the low-loss radio frequency cable is electrically connected to the connector.

6. The airtight armored low-loss radio frequency cable according to claim 1, characterized in that: The connector, the armor bellows connection and the external connection of the connector are all coated with silicone rubber to ensure airtightness.

7. The airtight armored low-loss radio frequency cable according to claim 3, characterized in that: The double-walled tube with adhesive is heat-shrunk and attached to the connection between the connector and the armored corrugated tube, and the identification sleeve is heat-shrunk and attached to the outside of the armored corrugated tube. After the transparent sleeve is heat-shrunk, the connector, the armored corrugated tube, the double-walled tube with adhesive and the identification sleeve are sealed at the same time.

8. A method for manufacturing an airtight armored low-loss radio frequency cable according to any one of claims 1 to 7, characterized in that: Here are the steps: S1. A low-loss RF cable is used as the backbone of the cable assembly. A layer of polyimide insulation layer and a multi-layer microporous film are respectively wrapped around the outer surface of the wire core of the low-loss RF cable to form a low-loss RF cable; S2. An armored corrugated tube is sheathed on the outside of the low-loss RF cable, and a polyurethane sheath is pre-extruded on the outside of the armored corrugated tube; S3. Insert the identification sleeve, transparent sleeve and double-walled tube with adhesive into both ends of the armored corrugated tube in sequence. The identification plate on the identification sleeve has a logo pointing to the connector; S4. Pre-pierce the components of the connector in sequence, and connect the tail of the connector to the end of the armor bellows; S5. Weld the conductors, assemble the connectors, and apply silicone rubber to the threads on the connectors to make them tightly connected to the external connectors; S6. Use a compression sleeve to press the connection between the connector and the armored bellows, and evenly apply silicone rubber to the connection between the connector and the armored bellows, and then attach the heat shrink tape double-wall tube to the connection between the connector and the armored bellows; S7. Carry out an airtight test. If it passes the test, heat shrink the identification sleeve on the outside of the armor bellows. Finally, heat shrink the transparent sleeve on the outside of the connector, armor bellows, double-walled tube with glue, and identification sleeve.

9. The method for manufacturing an airtight armored low-loss radio frequency cable according to claim 8, characterized in that: The ends of the low-loss radio frequency cable and the armored corrugated tube are both provided with connectors and are sealed and fixed.

10. The method for manufacturing an airtight armored low-loss radio frequency cable according to claim 8, characterized in that: The thickness of the polyurethane sheath outside the armor corrugated tube is between 0.5 and 0.55 mm, and the distance between the marking sleeve and the connector after heat shrinkage is 200 mm.

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