Leaky coaxial cable, interphone system and manufacturing method

Abstract

The invention relates to a leaky coaxial cable, an interphone system and a manufacturing method. The cable comprises an inner conductor; the insulating layer coats the outer surface of the inner conductor; the outer conductor coats the outer surface of the insulating layer; the POM sheath layer wraps the outer surface of the outer conductor, and a plurality of supporting columns extend outwards in the radial direction of the outer surface of the POM sheath layer in an integrated forming mode; the non-woven fabric wrapping layer is wrapped on the outer surfaces formed by the supporting columns, so that an air channel gap is formed between every two adjacent supporting columns; the flame-retardant sheath layer is coated on the outer surface of the non-woven fabric wrapping layer; the booster pump is arranged at one end of the leaky coaxial cable and is used for introducing pressurized gas into the gas circuit gap so as to cool the POM sheath layer; when the leaky coaxial cable is laid on the ground, the minimum gap between the slotted hole on the outer conductor and the ground is not less than 28mm. According to the invention, the signal coverage requirement of the fire-fighting intercom system in actual use can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of leaky coaxial cable, in particular to a leaky coaxial cable, a intercom system and a manufacturing method. BACKGROUND

[0002] Leaky coaxial cable (for short, leaky cable) is a coaxial communication cable with an incompletely closed outer conductor, and part of the signals transmitted or received on the cable can be coupled or radiated into the transmission system composed of the outer conductor and the external environment.

[0003] Referring to Figure 7 , during the underground site rescue process, the firefighters need to use intercoms to maintain normal communication with the internal personnel and the outside world. The intercom system is mainly composed of a signal source (signal source) dedicated to the intercom frequency band, a leaky coaxial cable (signal transmission carrier), a load (excess signal absorption), and an intercom (receiving end, transmitting end). When the firefighters are working on site, they hold an intercom in one hand, and the working range is within 1.5 meters around the leaky coaxial cable. There are firefighters working on both sides of the leaky coaxial cable at the same time. In addition, the leaky coaxial cable is laid on the ground, and the length of the cable is adjusted in time along with the change of the position of the fire fighting operation.

[0004] According to the energy coupling mechanism, the leaky coaxial cable is divided into coupling type and radiation type. Referring to Figure 8 , in the coupling mode leaky coaxial cable, there is a row of slots along the entire length of the cable, and the spacing of the slots is much smaller than the working wavelength. The electromagnetic field diffracts through the slots, exciting the electromagnetic field outside the outer conductor, so that there is current on the outer surface of the outer conductor, and thus electromagnetic radiation exists. Because in this mode the electromagnetic field diffracts through the small holes to excite the electromagnetic field outside the outer conductor. The resonant charge caused by the skin effect only moves along the outer surface of the shield conductor. The working principle of the coupling type leaky coaxial cable is the surface wave effect on the outer conductor.

[0005] Referring to Figure 9 , the radiation type leaky coaxial cable has a slot on the outer conductor with a slot spacing comparable to the wavelength (or half wavelength). The slot structure causes the signals at the slot to produce in-phase superposition. The leaked electromagnetic energy has directionality, so the field strength distribution along the line is less affected by environmental conditions, and the radial decay characteristics of the field are good.

[0006] Because the coupling type leaky cable slot excites "surface electromagnetic wave", the ground as a conductive medium will absorb and reflect electromagnetic waves, resulting in that the surface wave cannot be effectively transmitted and the signal decays quickly.

[0007] And the electromagnetic energy of the radiation type leaky cable has directionality. When the field firemen work, because the left and right sides of the cable need to be operated at the same time, the cable is laid randomly in the process, the slot holes cannot be ensured to be consistent, and thus the intercom signals of the left and right sides of the personnel are unstable.

[0008] Therefore, in order to ensure that the field firemen can obtain stable signals and maintain the normal communication of the internal personnel and the normal communication between the internal and external personnel, a new coupling type leaky cable is urgently needed to be developed for the fire intercom system of the field firemen. SUMMARY

[0009] Therefore, the application provides a leaky coaxial cable, an intercom system and a manufacturing method, which meet the signal coverage requirements of the fire intercom system in actual use.

[0010] To solve the above technical problems, the application provides a leaky coaxial cable, which comprises: an inner conductor; an insulating layer wrapped on the outer surface of the inner conductor; an outer conductor wrapped on the outer surface of the insulating layer, wherein a plurality of slot holes are arranged on the surface of the outer conductor and spaced along the axial direction, and the distance between adjacent slot holes is less than the working wavelength, so that the electromagnetic field is diffracted through the slot holes to form a surface wave on the outer conductor; a POM (polyoxymethylene) sheath layer wrapped on the outer surface of the outer conductor, wherein a plurality of support columns are integrally formed on the outer surface of the POM sheath layer and extend radially outward, each of the support columns extends along the length direction of the outer conductor, and adjacent two support columns are spaced by 45 degrees along the circumferential direction of the POM sheath layer; a non-woven fabric wrapping layer wrapped on the outer surface of each support column to form an air gap between each adjacent two support columns; a flame-retardant sheath layer wrapped on the outer surface of the non-woven fabric wrapping layer; a booster pump arranged at one end of the leaky coaxial cable and used for introducing booster gas into the air gap to cool the POM sheath layer; wherein the radial length of the support column is limited to be not less than 28 mm so that the minimum gap between the slot hole on the outer conductor and the ground when the leaky coaxial cable is laid on the ground.

[0011] In an embodiment of the application, the inner conductor is made of copper-clad aluminum material.

[0012] In an embodiment of the application, the support column is in the shape of a rectangular thin plate, and the end surface in contact with the POM sheath layer is in the shape of a rectangle or an arc.

[0013] In an embodiment of the present application, the radial length of the support column is not less than 28 mm, and the circumferential width is 3 mm±1 mm; the outer diameter of the POM sheath layer is 15.7 mm±0.25 mm.

[0014] In an embodiment of the present application, the outer diameter of the insulating layer is 12.6 mm±0.20 mm.

[0015] In an embodiment of the present application, the outer conductor adopts a ring-shaped corrugated copper pipe, and the slot holes are arranged at the positions of the wave crests; the outer diameter of the outer conductor is 13.9 mm±0.25 mm, and the diameter of the wave trough is 12.9 mm±0.25 mm.

[0016] In an embodiment of the present application, the non-woven fabric is a wrapping tape with a thickness of 0.18 mm±0.01 mm and a width of 35 mm±1 mm, and the wrapping coverage rate is 30%-50%; the outer diameter of the non-woven fabric wrapping layer is 44.3 mm±0.35 mm.

[0017] In an embodiment of the present application, the flame-retardant sheath layer adopts a low-smoke halogen-free flame-retardant sheath material with a density of 1.50 g / cm3; the outer diameter of the flame-retardant sheath layer is 45.1 mm±0.35 mm.

[0018] The present application also provides a speakerphone system comprising the leaky coaxial cable; wherein the two ends of the leaky coaxial cable are respectively provided with a first connector and a second connector, and the first connector and the second connector are respectively connected to a speakerphone signal source and a load through a jumper wire; The side wall of the first connector is provided with a gas injection hole, and a gas injection valve is threadedly connected to the gas injection hole; the gas injection valve is connected to the output end of the booster pump through a pipeline; The side wall of the second connector is threadedly connected with a check valve communicating with the air gap.

[0019] The present application also provides a manufacturing method of the leaky coaxial cable, comprising: S1, inner conductor preparation: providing copper-clad aluminum as the inner conductor; S2, insulating process: mixing high-density foaming material, low-density foaming material and nucleating agent according to a mass ratio of 71:25:4, and simultaneously injecting the mixture of the foaming material and gas formed by the high-purity carbon dioxide micro-foaming, pushing out the die module of the extruder through an extrusion die, forming a cell layer, and cooling and shaping the foam material insulating layer through a hot water tank and a cold water tank; the outer diameter of the insulating layer is 12.6 mm±0.20 mm. S3, copper strip corrugation slotting process: the copper strip with a thickness of 0.18 mm is sequentially subjected to cleaning, edge cutting, longitudinal packaging, forming, welding, and is rolled into a ring-shaped corrugated copper pipe, and a continuous hole is milled at the wave peak position according to a set hole pitch to form an outer conductor, wherein the outer diameter of the outer conductor is 13.9 mm ± 0.25 mm, and the valley diameter is 12.9 mm ± 0.25 mm; S4, POM sheath extrusion process: an extrusion die sleeve is provided, which comprises an extrusion cavity, and the extrusion cavity comprises a hole portion and an extrusion groove extending radially outward every 45° along the circumferential direction of the hole portion; The POM sheath material is extruded through the extrusion die sleeve to form a POM sheath layer on the outer conductor surface, and an integrally formed support column is extruded every 45° along the circumferential direction, the length of the support column is not less than 28 mm, the width is 3 mm ± 1 mm, the outer end surface is rectangular or arc-shaped, and the outer diameter of the sheath layer is 15.7 mm ± 0.25 mm; S5, sheath wrapping process: a concentric wrapping device is used to wrap non-woven fabric with a thickness of 0.18 mm ± 0.01 mm and a width of 35 mm ± 1 mm on the outer surface formed by each support column at a lap rate of 30% to 50% to form a non-woven fabric wrapping layer, and the outer diameter of the non-woven fabric wrapping layer is 44.3 mm ± 0.35 mm; S6, semi-finished product detection process: the semi-finished product formed in step S4 is detected, and after passing the detection, subsequent processes are carried out; S7, flame-retardant sheath layer extrusion process: low-smoke halogen-free flame-retardant sheath material with a density of 1.50 g / cm³ is extruded through a sheath extruder and pushed through a die to the surface of the non-woven fabric wrapping layer, the extrusion temperature is 125°C to 165°C, and a flame-retardant sheath layer with an outer diameter of 45.1 mm ± 0.35 mm is formed; S8, detection and disc forming: after disc forming, the finished product is detected, and after passing the detection, packaging, warehousing and delivery detection are carried out.

[0020] The above technical scheme of the present application has the following advantages compared with the prior art: The leaky coaxial cable, intercom system and manufacturing method of the present application integrally form a support column every 45° in the circumferential direction of the POM sheath layer, so that when the leaky coaxial cable is laid on the ground, the minimum gap between the outer conductor slot and the ground is not less than 28 mm, which can meet the requirement of the margin, effectively reduce the absorption and reflection loss of the surface wave signal by the ground, and directly lay the leaky coaxial cable on the ground without additional overhead.

[0021] The application utilizes the air path gap formed between the support columns, sets a booster pump at one end of the cable, and introduces booster gas into the air path, so as to realize rapid cooling of the POM sheath layer, improve the heat dissipation performance of the cable, and prolong the service life of the cable and maintain the signal transmission quality.

[0022] The POM sheath layer of the application adopts POM material to replace the traditional low-smoke halogen-free flame-retardant sheath material, significantly improves the hardness, wear resistance and impact resistance of the outer sheath, and can adapt to the working conditions such as frequent dragging and bending in the fire scene; the support column and the sheath layer are integrally extruded, reducing the assembly process and improving the overall structural strength and stability.

[0023] The non-woven fabric with a wrapping thickness of 0.18mm and a width of 35mm is wrapped around the outer surface of the support column, and the wrapping coverage rate is 30%-50%, which plays a continuous supporting role in the extrusion molding process of the flame-retardant sheath layer, prevents the local collapse or uneven thickness of the outer sheath due to the gap between the support columns, and improves the geometric consistency and appearance quality of the finished product.

[0024] In each process of the inner conductor foamed insulation layer, the outer conductor corrugated forming and slotting, the sheath layer and the flame-retardant sheath layer extrusion, the material specifications, outer diameter size and process parameters are limited, the outer diameter of the insulation layer is 12.6mm±0.20mm, the outer diameter of the outer conductor is 13.9mm±0.25mm, and the outer diameter of the flame-retardant sheath layer is 45.1mm±0.35mm, which cooperates with multiple detections of semi-finished products and finished products to ensure the dimensional accuracy and performance stability in batch production.

[0025] The first connector and the second connector are respectively arranged at two ends of the leaky coaxial cable, which can be conveniently connected to the intercom signal source, the terminal load and the booster pump system, adapt to the commonly used fire intercom interface, and facilitate rapid deployment and maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to make the content of the application more easily understood, the application will be further described in detail below according to the specific embodiments of the application and in conjunction with the drawings.

[0027] Figure 1 is a schematic view of the cross-sectional structure of the leaky coaxial cable of the application.

[0028] Figure 2 is a schematic view of the longitudinal cross-sectional structure of the leaky coaxial cable of the application.

[0029] Figure 3 is a schematic view of the axial side structure of the POM sheath layer of the application.

[0030] Figure 4 is a schematic view of the intercom system of the application.

[0031] Figure 5It is a structural schematic diagram of the extrusion die sleeve of the present application.

[0032] Figure 6 It is a flow chart of the manufacturing method of the leaky coaxial cable of the present application.

[0033] Figure 7 It is a schematic diagram of the application scene of the leaky cable for the fire intercom system.

[0034] Figure 8 It is a radiation principle diagram of the coupling type leaky cable.

[0035] Figure 9 It is a radiation principle diagram of the radiation type leaky cable.

[0036] Figure 10 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed on the ground.

[0037] Figure 11 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed 28mm away from the ground.

[0038] Figure 12 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed 42mm away from the ground.

[0039] Figure 13 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed 56mm away from the ground.

[0040] Figure 14 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed 80mm away from the ground.

[0041] Figure 15 It is a signal loss diagram obtained by testing when the leaky coaxial cable of the present application is placed 500mm away from the ground.

[0042] Figure 16 It is a picture of the leaky coaxial cable during testing (overhead cushion test).

[0043] Explanation of the reference signs in the specification: 100, leaky coaxial cable; 110, first connector; 111, gas injection hole; 120, second connector; 130, load; 140, intercom; 150, gas injection valve; 160, check valve; 200, extrusion die sleeve; 210, hole part; 220, extrusion groove; 1, inner conductor; 2, insulation layer; 3, outer conductor; 31, slot hole; 4, POM sheath layer; 41, support column; 5, non-woven fabric wrapping layer; 6. Air gap 7. Flame-retardant sheath layer 8. Booster pump; 82. Conduit DETAILED DESCRIPTION

[0044] The present application will be further described below in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand and implement the present application, but the embodiments are not intended to limit the present application.

[0045] In the present application, if the directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solutions of the present application, and is not intended to indicate or imply that the indicated technical features must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0046] In the present application, the meaning of "several" is one or more, the meaning of "multiple" is two or more, and "greater than", "less than", "exceeding" and the like are understood as not including the number; "above", "below", "within" and the like are understood as including the number. In the description of the present application, if "first" and "second" are described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0047] In the present application, unless otherwise explicitly limited, the words "set", "install", "connect" and the like should be broadly understood, for example, they can be directly connected, or indirectly connected through an intermediate medium; can be fixedly connected, or can be detachably connected, or can be integrally formed; can be mechanically connected, or can be electrically connected or capable of communicating with each other; can be the communication or interaction relationship between two elements. The skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solutions.

[0048] Referring to Figures 1 to 3 The leaky coaxial cable 100 of the present embodiment includes: an inner conductor 1; an insulating layer 2 covering the outer surface of the inner conductor 1; an outer conductor 3 covering the outer surface of the insulating layer 2, and a plurality of slot holes 31 are formed along the surface of the outer conductor 3 and spaced along the axial direction, the distance between adjacent slot holes 31 is less than the working wavelength, so that the electromagnetic field is diffracted through the slot holes 31, thereby forming a surface wave on the outer conductor 3; A POM sheath layer 4 is wrapped around the outer surface of the outer conductor 3, wherein a plurality of support columns 41 are integrally formed along the outer surface of the POM sheath layer 4 radially outward, each of the support columns 41 extends along the length direction of the outer conductor 3, and two adjacent support columns 41 are spaced 45° along the circumferential direction of the POM sheath layer 4; A non-woven fabric wrapping layer 5 is wrapped around the outer surface of each of the support columns 41 to form an air path gap 6 between every two adjacent support columns 41; A flame-retardant sheath layer 7 is wrapped around the outer surface of the non-woven fabric wrapping layer 5; A booster pump 8 is arranged at one end of the leaky coaxial cable 100 to introduce pressurized gas into the air path gap 6 to cool the POM sheath layer 4; The radial length of the support column 41 is limited to be not less than 28 mm, so that when the leaky coaxial cable 100 is laid on the ground, the minimum gap between the slot hole 31 on the outer conductor 3 and the ground is not less than 28 mm.

[0049] It should be noted that through on-site debugging, it is found that when the coupling type leaky coaxial cable 100 is kept at a certain height interval from the ground, the received signal of the interphone 140 can be obviously improved; when the height of the leaky cable from the ground reaches 28 mm, the interphone 140 can stably receive signals to meet normal communication needs.

[0050] On-site testing and verification is carried out, and the test conditions are as follows: the leaky cable transmission power is 15 dBm; the test frequency (frequency 1) is 450 MHz; the test distance is 50 m; the judgment standard: generally, the coupling loss is less than 80 db, which is better; the test height from the ground: placed on the ground, 28 mm from the ground, and the overhead section is about 14-28 m, 42 mm from the ground, and the overhead section is about 13-32 m, 56 mm from the ground, and the overhead section is about 7-28 m, 80 mm from the ground, and the overhead section is about 5-37 m, 500 mm from the ground, and the overhead section is about 18-43 m. Referring to Figures 10 to 16 .

[0051] It should be noted that during the leakage cable test, a measurement is taken every 1 mm, and the computer automatically records the corresponding test point number and test value. Taking a 50m length as an example, a total of 5000 test data can be obtained. The so-called 95% coupling loss value refers to the test value corresponding to the 4750th point (i.e. 5000 x 0.95 = 4750) after arranging the 5000 test data in descending order as the 95% coupling loss value of the whole cable. In the specific operation, the host computer system will automatically collect all the test data, and after sorting, automatically select the data point value at the 95% position as the final result. The coupling loss value directly comes from the data collected by the computer and corresponds to the test point one by one. According to the total number of collected points, the corresponding coupling loss value can be quickly determined according to the total number of points x 0.95.

[0052] Referring to Figures 10 to 15 It can be seen that when the leakage cable is placed on the ground, the received signal strength is poor (i.e. the coupling loss is high); when the leakage cable is 28mm away from the ground, the received signal strength has been significantly improved (within 28mm from the ground, it is not much different from when the leakage cable is placed on the ground, so it is not shown, and 28mm can meet the requirement of the gap); as the height from the ground increases, the received signal strength continues to increase; when the height from the ground reaches 500mm, the signal strength tends to be stable and no longer increases significantly. Therefore, the leakage cable can realize stable coverage of the intercom 140 signal when the height from the ground is more than 28mm, meeting the communication requirements of the fire intercom system in complex underground environments.

[0053] Therefore, through the arrangement of the support column 41, the cable can naturally maintain a gap of more than 28mm when laid on the ground, meeting the signal coverage requirements of the fire intercom system in actual use.

[0054] In addition, by introducing a booster pump 8 to introduce pressurized gas into the air path through the air path gap 6 formed between the support columns 41, the POM sheath layer 4 can be quickly cooled, prolonging the service life and maintaining the signal transmission quality.

[0055] Specifically, the inner conductor 1 is made of copper-clad aluminum material.

[0056] Specifically, the support column 41 is in the shape of a rectangular thin plate, and the end face in contact with the POM sheath layer 4 is in the shape of a rectangle or an arc. The radial length of the support column 41 is not less than 28mm, and the circumferential width is 3mm±1mm; the outer diameter of the POM sheath layer 4 is 15.7mm±0.25mm. The radial length of the support column 41 can ensure that the minimum gap between the cable slot hole 31 and the ground is not less than 28mm, avoiding the absorption of surface wave signals by the ground; the width design ensures sufficient support strength under the action of gravity, preventing the cable from collapsing and stabilizing the distance from the ground.

[0057] Referring to Figure 3As shown, the end face of the support column 41 adopts a rectangular or arc-shaped structure, which can increase the contact area with the material of the non-woven fabric wrapping layer 5, so that the non-woven fabric can uniformly and stably cover the outer surface of the support column 41 in the subsequent wrapping process.

[0058] In addition, the outer conductor 3 is coated with a POM (polyoxymethylene) material instead of the original low-smoke halogen-free flame-retardant sheath material to improve the mechanical strength, wear resistance and overall protection performance of the sheath.

[0059] Specifically, the outer diameter of the insulating layer 2 is 12.6 mm±0.20 mm.

[0060] Specifically, the outer conductor 3 adopts a ring-shaped corrugated copper pipe, and the slot hole 31 is arranged at the wave peak position; the outer diameter of the outer conductor 3 is 13.9 mm±0.25 mm, and the valley diameter is 12.9 mm±0.25 mm.

[0061] Specifically, the non-woven fabric is a wrapping tape with a thickness of 0.18 mm±0.01 mm and a width of 35 mm±1 mm, and the wrapping coverage rate is 30%~50%; the outer diameter of the non-woven fabric wrapping layer 5 is 44.3 mm±0.35 mm.

[0062] By coating a layer of non-woven fabric material on the outer surface of each support column 41, the local collapse caused by the gap between the support columns 41 during the extrusion molding of the flame-retardant sheath layer 7 is prevented, thereby ensuring the molding integrity and flatness of the outer sheath.

[0063] Specifically, the flame-retardant sheath layer 7 adopts a low-smoke halogen-free flame-retardant sheath material with a density of 1.50 g / cm³, and the outer diameter of the flame-retardant sheath layer 7 is 45.1 mm±0.35 mm.

[0064] Referring to Figure 4 As shown, the present embodiment also provides a intercom system, comprising the leaky coaxial cable 100; wherein the two ends of the leaky coaxial cable 100 are respectively provided with a first connector 110 and a second connector 120, the first connector 110 and the second connector 120 are respectively connected to the signal source of the intercom 140 and the load 130 through the jumper wires; the side wall of the first connector 110 is provided with a gas injection hole 111 and is threadedly connected with a gas injection valve 150 through the gas injection hole 111, the gas injection valve 150 is connected with the output end of the booster pump 8 through the pipeline 82; the side wall of the second connector 120 is threadedly connected with a check valve 160 which is connected with the air gap 6.

[0065] Specifically, the first connector 110 and the second connector 120 are conveniently connected with the intercom 140 signal source and the load 130, facilitating deployment and maintenance. The gas injection valve 150 and the check valve 160 are both single-leaf swing valves made of stainless steel, which are highly corrosion resistant. The check valve 160 is a one-way flow valve that automatically opens or closes to prevent the backflow of the medium in the pipeline.

[0066] Exemplarily, the gas injection power of the booster pump 8 is set to 3kw, which can meet the requirement of cooling the POM sheath layer 4.

[0067] Referring to Figure 6 It should be noted that when the booster pump 8 is working, the high-pressure gas flows at high speed along the air gap 6, and the injected gas flow is ambient temperature air (or low-temperature gas), which can carry away the heat in the cable and reduce the surface temperature of the POM sheath layer 4.

[0068] The embodiment also provides a manufacturing method of the leaky coaxial cable 100, comprising: S1, preparing the inner conductor 1: providing copper-clad aluminum as the inner conductor 1; S2, an insulation process: mixing high-density foaming material, low-density foaming material, and nucleating agent at a mass ratio of 71:25:4, and simultaneously injecting a mixture of the foaming material and gas formed by micro-foaming of high-purity carbon dioxide, using an extrusion die to push the extruder die module to form a cell layer, and cooling and shaping the cell layer in a hot water tank and a cold water tank to form a foam material insulation layer 2, wherein the outer diameter of the insulation layer 2 is 12.6mm±0.20mm; S3, a copper strip corrugation and slotting process: sequentially cleaning, edge cutting, longitudinal wrapping, forming, and welding a copper strip with a thickness of 0.18mm to mill a hole at a set hole pitch at the wave peak position to form an outer conductor 3, wherein the outer diameter of the outer conductor 3 is 13.9mm±0.25mm, and the valley diameter is 12.9mm±0.25mm; S4, a POM sheath extrusion process: providing an extrusion die set 200, wherein the extrusion die set 200 comprises an extrusion cavity, and the extrusion cavity comprises a hole portion 210 and an extrusion groove 220 extending radially outward at every 45° along the circumferential direction of the hole portion 210; referring to Figure 5 ; The sheath material made of POM is extruded through the extrusion die set 200 to form the POM sheath layer 4 on the surface of the outer conductor 3, and at the same time, an integrally formed support column 41 is extruded at every 45° along the circumferential direction of the POM sheath layer 4, wherein the length of the support column 41 is not less than 28mm, the width is 3mm±1mm, the outer end face is rectangular or arc-shaped, and the outer diameter of the sheath layer is 15.7mm±0.25mm; S5, sheath winding process: using concentric winding equipment, the thickness of 0.18mm±0.01mm, width of 35mm±1mm non-woven fabric with 30%~50% overlap rate winding on the outer surface of each support column 41 formed, forming non-woven fabric winding layer 5, the outer diameter of the non-woven fabric winding layer 5 is 44.3mm±0.35mm; S6, semi-finished product detection process: the semi-finished product formed in step S4 is detected, and after passing the test, the subsequent process is carried out; S7, flame-retardant sheath layer 7 extrusion process: the low smoke halogen-free flame-retardant sheath material with a density of 1.50g / cm³ is extruded through the sheath extruder and pushed to the surface of the non-woven fabric winding layer 5 through the mold, the extrusion temperature is 125℃~165℃, forming a flame-retardant sheath layer 7 with an outer diameter of 45.1mm±0.35mm; S8, detection and disc forming: after disc forming, the finished product is detected, and after passing the test, it is packaged, stored and shipped.

[0069] Through each process of foaming insulation layer 2 in inner conductor 1, outer conductor 3 corrugated forming and slotting, sheath layer and flame-retardant sheath layer 7 extrusion, the material specification, outer diameter size and process parameters are limited, and the semi-finished product and finished product are detected multiple times, to ensure the size accuracy and performance stability in batch production.

[0070] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A leaky coaxial cable, characterized in that: include: inner conductor (1); An insulating layer (2) covering the outer surface of the inner conductor (1); An outer conductor (3) is coated on the outer surface of the insulating layer (2), and slots (31) are provided along the surface of the outer conductor (3) at intervals along the axial direction, and the spacing between adjacent slots (31) is smaller than the operating wavelength, so that the electromagnetic field is diffracted through the slots (31), thereby forming a surface wave on the outer conductor (3); A POM sheath layer (4) is coated on the outer surface of the outer conductor (3), wherein a plurality of support columns (41) are integrally formed and radially extend outward along the outer surface of the POM sheath layer (4), each support column (41) extends along the length direction of the outer conductor (3), and two adjacent support columns (41) are spaced 45 degrees apart along the circumferential direction of the POM sheath layer (4); A non-woven fabric wrapping layer (5) is wrapped around the outer surface formed by each of the support columns (41), so that an air path gap (6) is formed between each two adjacent support columns (41); A flame-retardant sheath layer (7) coated on the outer surface of the non-woven fabric wrapping layer (5); A booster pump (8) is arranged at one end of the leaky coaxial cable and is used to pass pressurized gas into the gas path gap (6) to cool the POM sheath layer (4); The radial length of the support column (41) is limited so that when the leaky coaxial cable is laid on the ground, the minimum gap between the slot (31) on the outer conductor (3) and the ground is not less than 28 mm.

2. A leaky coaxial cable according to claim 1, characterized in that: The inner conductor (1) is made of copper-clad aluminum material.

3. The leaky coaxial cable according to claim 1, wherein: The support column (41) is in the shape of a rectangular thin plate, and the end surface in contact with the POM sheath layer (4) is rectangular or arc-shaped.

4. The leaky coaxial cable according to claim 1, wherein: The radial length of the support column (41) is not less than 28 mm, and the circumferential width is 3 mm ± 1 mm; the outer diameter of the POM sheath layer (4) is 15.7 mm ± 0.25 mm.

5. The leaky coaxial cable according to claim 1, characterized in that: The outer diameter of the insulating layer (2) is 12.6 mm ± 0.20 mm.

6. The leaky coaxial cable according to claim 1, characterized in that: The outer conductor (3) is an annular corrugated copper tube, and the slot (31) is provided at the crest position; the outer diameter of the outer conductor (3) is 13.9 mm ± 0.25 mm, and the trough diameter is 12.9 mm ± 0.25 mm.

7. The leaky coaxial cable according to claim 1, characterized in that: The non-woven fabric is a wrapping tape with a thickness of 0.18 mm ± 0.01 mm and a width of 35 mm ± 1 mm, a wrapping overlap rate of 30% to 50%, and an outer diameter of the non-woven fabric wrapping layer (5) of 44.3 mm ± 0.35 mm.

8. The leaky coaxial cable according to claim 1, characterized in that: The flame retardant sheath layer (7) is made of a low-smoke halogen-free flame retardant sheath material with a density of 1.50 g / cm³, and the outer diameter of the flame retardant sheath layer (7) is 45.1 mm ± 0.35 mm.

9. A walkie-talkie system, characterized in that: The leaky coaxial cable comprises the leaky coaxial cable according to any one of claims 1 to 8; wherein a first connector (110) and a second connector (120) are respectively provided at both ends of the leaky coaxial cable, and the first connector (110) and the second connector (120) are respectively connected to a signal source of a walkie-talkie (140) and a load (130) via jumpers; A gas injection hole (111) is provided on the side wall of the first connector (110), and a gas injection valve (150) is threadedly connected to the gas injection hole (111), and the gas injection valve (150) is connected to the output end of the booster pump (8) through a pipeline (82); The side wall of the second connector (120) is threadedly connected to a check valve (160) that is in communication with the air path gap (6).

10. A method for manufacturing a leaky coaxial cable according to any one of claims 1 to 8, characterized in that: include: S1. Preparation of inner conductor (1): providing copper-clad aluminum as inner conductor (1); S2, insulation process: high-density foaming material, low-density foaming material and nucleating agent are mixed in a mass ratio of 71:25:4, and high-purity carbon dioxide is injected into the mixture of foaming material and gas at the same time, and an extrusion die is used to push the extruder die module to form a cellular layer, which is cooled and shaped in a hot water tank and a cold water tank to form an insulation layer (2) of foam material, wherein the outer diameter of the insulation layer (2) is 12.6 mm ± 0.20 mm; S3, copper strip corrugation and grooving process: a copper strip with a thickness of 0.18 mm is sequentially cleaned, trimmed, longitudinally wrapped, formed, and welded to be rolled into an annular corrugated copper tube, and holes are continuously milled at the crest position according to a set hole pitch to form an outer conductor (3), wherein the outer diameter of the outer conductor (3) is 13.9 mm ± 0.25 mm, and the trough diameter is 12.9 mm ± 0.25 mm; S4, POM sheath extrusion process: providing an extrusion die sleeve (200), the extrusion die sleeve (200) comprising an extrusion cavity, the extrusion cavity comprising a hole portion (210) and extrusion grooves (220) extending radially outward at intervals of 45° along a circumferential direction of the hole portion (210); A POM sheath material is used, and while a POM sheath layer (4) is extruded on the surface of the outer conductor (3) through the extrusion die sleeve (200), an integrally formed support column (41) is extruded every 45° along the circumferential direction thereof, the support column (41) having a length of not less than 28 mm and a width of 3 mm ± 1 mm, an outer end face being rectangular or arc-shaped, and an outer diameter of the sheath layer being 15.7 mm ± 0.25 mm; S5, sheath wrapping process: using concentric wrapping equipment, wrapping a non-woven fabric with a thickness of 0.18 mm ± 0.01 mm and a width of 35 mm ± 1 mm on the outer surface formed by each support column (41) at an overlap rate of 30% to 50% to form a non-woven fabric wrapping layer (5), wherein the outer diameter of the non-woven fabric wrapping layer (5) is 44.3 mm ± 0.35 mm; S6, semi-finished product inspection process: the semi-finished product formed in step S4 is inspected, and the subsequent process is carried out after it passes the inspection; S7, flame retardant sheath layer (7) extrusion process: extrude low smoke halogen-free flame retardant sheath material with a density of 1.50g / cm³ through a sheath extruder, and push it onto the surface of the non-woven fabric wrapping layer (5) through a die, at an extrusion temperature of 125°C to 165°C, to form a flame retardant sheath layer (7) with an outer diameter of 45.1mm±0.35mm; S8. Inspection and packaging: After packaging, the finished products will be inspected. If they are qualified, they will be packaged, put into storage and shipped.

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