Flame-retardant leaky cable and production method

Abstract

Disclosed in the present invention are a flame-retardant leaky cable and a production method. The flame-retardant leaky cable comprises a sheath, an outer conductor, an insulating layer and an inner conductor which are sequentially arranged from outside to inside. A flame-retardant layer is longitudinally arranged between the sheath and the outer conductor or between the outer conductor and the insulating layer; the flame-retardant layer is a mica tape or PTFE; a plurality of radiation slot holes are formed on the outer conductor; the inner conductor is a spiral copper tube or a smooth copper tube; when the flame-retardant layer is longitudinally arranged between the sheath and the outer conductor, and only covers the radiation slot holes. According to the present invention, the flame-retardant layer having a low dielectric constant is longitudinally arranged between the outer conductor and the sheath or between the insulating layer and the outer conductor, so that the flame-retardant grade of the leaky cable is effectively improved, and the flame-retardant requirements of related laying places are met.

Description

Flame-retardant leaky cable and production method Technical Field

[0001] The invention belongs to the technical field of leaky cables, and in particular relates to a flame-retardant leaky cable and a production method thereof. Background Art

[0002] With the continuous development of the communications industry, leaky cables are often used for communication transmission in special environments such as tunnels, mines, and coal mines, where wireless signal transmission is poor or impossible. By providing openings in the outer conductor of the leaky cable to radiate and receive electromagnetic wave signals, it performs the dual functions of signal transmission line and transceiver antenna. Due to the harsh environments in tunnels, mines, and coal mines, the quality and flame retardancy requirements for leaky cables are generally high. However, the current structure of leaky cables does not meet the flame retardancy requirements.

[0003] Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a flame retardant leaky cable and a production method.

[0005] In order to achieve the above-mentioned purpose and the above-mentioned technical effect, the technical solution adopted by the present invention is:

[0006] A flame-retardant leaky cable comprising a sheath, an outer conductor, an insulating layer, and an inner conductor arranged in sequence from the outside to the inside; a flame-retardant layer is longitudinally wrapped between the sheath and the outer conductor or between the outer conductor and the insulating layer, the flame-retardant layer being a mica tape or PTFE; a plurality of radiating slots are provided on the outer conductor; and the inner conductor is a spiral copper tube or a smooth copper tube;

[0007] When the flame retardant layer is longitudinally wrapped between the sheath and the outer conductor, it only covers the radiation slots.

[0008] Furthermore, the radiation slot has a slot length of 10-30 mm and a slot width of 2-4 mm.

[0009] Furthermore, the angle between the radiation slot and the central axis of the leaky cable is 10-30°.

[0010] Furthermore, the radiation slot is in a straight or U shape.

[0011] Furthermore, when the flame retardant layer is longitudinally wrapped between the sheath and the outer conductor, a water-blocking layer is provided between the sheath and the flame retardant layer, and the outside of the water-blocking layer is evenly coated with a rat- and ant-proof ointment layer.

[0012] Furthermore, the thickness of the rat and ant-proof ointment layer is 0.5-3 mm.

[0013] Furthermore, the thickness of the sheath is 1.4±0.2 mm or 1.9±0.2 mm.

[0014] Furthermore, the thickness of the flame retardant layer is 0.13±0.01 mm.

[0015] Furthermore, the thickness of the outer conductor is 0.075 mm-0.09 mm.

[0016] Furthermore, the thickness of the inner conductor is 0.2 mm-0.45 mm.

[0017] A method for producing a flame-retardant leaky cable, the flame-retardant leaky cable comprising a sheath, an outer conductor, an insulating layer, and an inner conductor arranged in sequence from the outside to the inside; a flame-retardant layer longitudinally wrapped between the sheath and the outer conductor, the flame-retardant layer being a mica tape or PTFE; a plurality of radiating slots being provided on the outer conductor, the flame-retardant layer only covering the radiating slots; and the inner conductor being a spiral copper tube or a smooth copper tube; the method comprising the following steps:

[0018] 1) The copper strip with the radiation slots punched is unwound using a tension-free outer conductor active unwinding rack. The unwinding speed is controlled by an induction controller. The unwinding speed is determined by the production speed and is 8-10 m / min. The copper strip with the radiation slots punched is passed through a tape storage box, a guide positioning piece, three sets of forming wheels, and then through an airplane mold to be longitudinally wrapped into a circle, ensuring that the leakage part of the copper strip with the radiation slots punched is subjected to minimal force, ensuring formation, and thus ensuring that the slots are not stressed; the mica tape or PTFE is unwound through a flame retardant layer unwinding rack, then through a tape storage box, a guide positioning piece, three sets of forming wheels, and then through an airplane mold to be longitudinally wrapped around the outer conductor 3. The longitudinal wrapping width is 20-60 mm, and the outer conductor and the flame retardant layer are longitudinally wrapped at the same time;

[0019] 2) The physical foam cable core consisting of an inner conductor and an insulating layer is introduced into the aircraft mold through a cable core active pay-off frame using a constant tension traction force of 70 to 90 N. The cable core is then combined with the initially formed outer conductor with a flame retardant layer, and the outer conductor with the flame retardant layer is wrapped around the outer periphery of the physical foam cable core.

[0020] 3) Subsequently, the semi-finished product obtained in step 2) is sized by passing it through a sizing die; if a water-blocking layer is required, the water-blocking layer is directly wrapped around the flame-retardant layer, and then a layer of rat and ant-proof ointment is applied before proceeding to step 4);

[0021] 4) The semi-finished product obtained in step 3) is fed into an extruder via a guide wheel to be coated with a sheath. The molten polyethylene is extruded from the extruder head by the extruder at a temperature of 200-220° C. After the sheath is formed, the obtained leaky cable is cooled in sections, first by cooling in hot water at 32-36° C., then in a cold water tank at 20-24° C., and finally cooled to room temperature. The cable is then printed with a label and then passed to a main traction machine, where it is pulled onto a take-up reel and taken up on the reel.

[0022] A method for producing a flame-retardant leaky cable, the flame-retardant leaky cable comprising a sheath, an outer conductor, an insulating layer, and an inner conductor arranged in sequence from the outside to the inside, a flame-retardant layer longitudinally wrapped between the outer conductor and the insulating layer, the flame-retardant layer being a mica tape or PTFE, the outer conductor being provided with a plurality of radiating slots, and the inner conductor being a spiral copper tube or a smooth copper tube; the method comprising the following steps:

[0023] 1) The physical foam cable core consisting of the inner conductor and the insulation layer is introduced into the aircraft model through the cable core active pay-off frame using constant tension traction, with a constant tension traction force of 70 to 90N;

[0024] 2) The mica tape or PTFE is unwound through the flame retardant layer pay-off frame, passes through the guide positioning parts, passes through three sets of forming wheels, is introduced into the aircraft mold, and merges with the physical foaming cable core;

[0025] At the same time, the copper strip with the radiation slots punched is unwound by a tension-free outer conductor active unwound rack. The unwound speed is controlled by an induction controller and is determined by the production speed. The unwound speed is 8-10m / min. The copper strip with the radiation slots punched is passed through a tape storage box, a guide positioning piece, and three sets of forming wheels and introduced into the aircraft mold. The outer conductor and the flame retardant layer are longitudinally wrapped at the same time.

[0026] 3) The semi-finished product obtained in step 2) is sized by a sizing die, and is fed into an extruder through a guide wheel to be coated with a sheath. The molten polyethylene is extruded from the extruder head by the extruder, and the extrusion temperature is controlled at 200-220°C. After the sheath is formed, the obtained leaky cable is cooled in sections, first cooled by hot water at 32-36°C, and then cooled in a cold water tank at 20-24°C. The leaky cable is cooled to room temperature, printed with a code, and then sent to the main traction machine, where it is pulled onto the take-up reel and the cable is taken up on the reel.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention discloses a flame-retardant leaky cable and a production method thereof. By longitudinally wrapping a flame-retardant layer with a low dielectric constant between an outer conductor and a sheath or between an insulating layer and an outer conductor, the flame-retardant grade of the leaky cable is effectively improved, thereby meeting the flame-retardant requirements of relevant laying sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of a flame-retardant leaky cable according to embodiment 1 of the present invention;

[0030] FIG2 is a production flow chart of a flame-retardant leaky cable according to Example 1 of the present invention;

[0031] FIG3 is a schematic structural diagram of a flame-retardant leaky cable according to embodiment 2 of the present invention;

[0032] FIG4 is a production flow chart of a flame-retardant leaky cable according to Example 2 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0034] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0035] Example 1

[0036] As shown in Figures 1-2, a flame-retardant leaky cable comprises, arranged in order from outside to inside, a sheath 1, a flame-retardant layer 2, an outer conductor 3, an insulating layer 4, and an inner conductor 5. The sheath 1 is made of polyethylene, the flame-retardant layer 2 is made of low-dielectric-constant mica tape or PTFE, and is longitudinally wrapped between the sheath 1 and the outer conductor 3. The outer conductor 3 is made of corrugated copper tape with multiple radiating slots 31, and the flame-retardant layer 2 is longitudinally wrapped to cover only the radiating slots 31. The insulating layer 4 is a high-density or low-density foam layer, and the inner conductor 5 is a spiral-corrugated copper tube or a smooth copper tube made of copper tape. The flame-retardant leaky cable of Example 1 meets the requirements of the single-cable combustion test of GB / T 18380.12-2008.

[0037] According to the leaky cable model, the thickness of the sheath 1 is generally 1.4±0.2mm or 1.9±0.2mm, the thickness of the flame retardant layer 2 is generally 0.13±0.01mm, the thickness of the outer conductor 3 is generally 0.075mm-0.09mm, the thickness of the inner conductor 5 is generally 0.2mm-0.45mm, and the thickness of the insulating layer 4 is 24.8±0.3mm, 19.4±0.3mm or 11.3±0.3mm, etc.

[0038] The outer conductor 3 is provided with a plurality of radiation slot groups 6. Two adjacent radiation slot groups 6 are symmetrically arranged along the symmetry axis. Each radiation slot group 6 includes a plurality of parallel and spaced radiation slots 31. The two symmetrical radiation slots 31 in the two adjacent radiation slot groups 6 are in an eight-shaped shape. The slot length of the radiation slot 31 is 10-30 mm, the slot width is 2-4 mm, and the angle between the radiation slot 31 and the central axis of the leaky cable is 10-30°.

[0039] In order to better adapt to the harsh environments such as tunnels, mines, and coal mines, the outside of the flame retardant layer 2 can be provided with a water-blocking layer with a thickness of 1-2 mm according to needs, which is wrapped to meet the waterproof performance of the leaky cable. The outside of the water-blocking layer is evenly coated with a 0.5-3 mm thick anti-rat and ant ointment layer to prevent rats and ants. The outside of the water-blocking layer coated with the anti-rat and ant ointment layer is the sheath 1.

[0040] A method for producing a flame-retardant leaky cable comprises the following steps:

[0041] 1) The copper tape with the radiation slots 31 punched is unwound by a tension-free outer conductor active unwinding rack 6, and the unwinding speed is controlled by an induction controller. The unwinding speed is determined by the production speed, and the unwinding speed is generally 8 to 10 m / min. The copper tape with the radiation slots 31 punched is passed through a tape storage box 7, a guide positioning piece 8, three sets of forming wheels 9, and then an airplane mold 10 to be longitudinally wrapped into a circle, ensuring that the leakage part of the copper tape with the radiation slots 31 punched is subjected to minimal force, ensuring forming, and thus ensuring that the slots are not subjected to force; since the outer conductor 3 and the flame retardant layer 2 are longitudinally wrapped at the same time, the flame retardant layer 2 is not longitudinally wrapped after the outer conductor 3 is longitudinally wrapped. Therefore, in this step, the flame retardant layer 2 will be longitudinally wrapped on the outside of the outer conductor 3 at the same time, and the mica tape or PTFE is unwound through the flame retardant layer unwinding rack 11, and then passed through the tape storage box 7, the guide positioning piece 8, the three sets of forming wheels 9, and then passed through the airplane mold 10 to be longitudinally wrapped on the outside of the outer conductor 3, with a longitudinal wrapping width of 20 to 60 mm;

[0042] 2) The physical foam cable core consisting of the inner conductor 5 and the insulating layer 4 is introduced into the aircraft model 10 by the cable core active pay-off frame 12 using a constant tension traction force of 70 to 90 N, and is combined with the initially formed outer conductor 3 with the flame retardant layer 2, and the outer conductor 3 with the flame retardant layer 2 is coated on the periphery of the physical foam cable core;

[0043] 3) Subsequently, the semi-finished product obtained in step 2) is sized by a sizing die 13; if a water-blocking layer is required, the water-blocking layer is directly wrapped around the flame-retardant layer 2, and then a layer of rat and ant-proof ointment is applied before proceeding to step 4);

[0044] 4) The semi-finished product obtained in step 3) is fed into an extruder 14 via a guide wheel for polyethylene coating to form a sheath 1. The molten polyethylene is extruded from the extruder head via the extruder 14 at a temperature of 200-220° C. After the sheath 1 is formed, the obtained leaky cable is cooled in stages, first by cooling it in hot water at 32-36° C., then by cooling it in a cold water tank at 20-24° C., and finally cooled to room temperature. The cable is then printed with a label and then fed to a main traction machine, where it is pulled onto a take-up reel and taken up on the reel.

[0045] Example 2

[0046] As shown in Figures 3-4, a flame-retardant leaky cable comprises, arranged in order from outside to inside, a sheath 1, an outer conductor 3, a flame-retardant layer 2, an insulating layer 4, and an inner conductor 5. The sheath 1 is made of polyethylene, the flame-retardant layer 2 is made of mica tape or PTFE, and is longitudinally wrapped between the outer conductor 3 and the insulating layer 4. The outer conductor 3 is made of corrugated copper tape with multiple radial slots 31, the insulating layer 4 is a high-density or low-density foam layer, and the inner conductor 5 is a spiral copper tube made of copper tape (depending on the leaky cable model, the outer diameter after drawing is 8.0±0.1mm for 50-19, 12.8±0.1mm for 50-32, and 18.0±0.1mm for 50-42) or a smooth copper tube. The flame-retardant leaky cable of Example 1 meets the requirements of the single cable combustion test of GB / T 18380.12-2008.

[0047] According to the leaky cable model, the thickness of the sheath 1 is generally 1.4±0.2mm or 1.9±0.2mm, the thickness of the flame retardant layer 2 is generally 0.13±0.01mm, the thickness of the outer conductor 3 is generally 0.075mm-0.09mm, the thickness of the inner conductor 5 is generally 0.2mm-0.45mm, and the thickness of the insulating layer 4 is 24.8±0.3mm, 19.4±0.3mm or 11.3±0.3mm, etc.

[0048] The outer conductor 3 is provided with a plurality of radiation slot groups 6. Two adjacent radiation slot groups 6 are symmetrically arranged along the symmetry axis. Each radiation slot group 6 includes a plurality of parallel and spaced radiation slots 31. The two symmetrical radiation slots 31 in the two adjacent radiation slot groups 6 are in an eight-shaped shape. The slot length of the radiation slot 31 is 10-30 mm, the slot width is 2-4 mm, and the angle between the radiation slot 31 and the central axis of the leaky cable is 10-30°.

[0049] A method for producing a flame-retardant leaky cable comprises the following steps:

[0050] 1) The physically foamed cable core consisting of the inner conductor 5 and the insulating layer 4 is introduced into the aircraft model 10 by a cable core active pay-off frame 12 using a constant tension traction force of 70 to 90 N;

[0051] 2) The mica tape or PTFE is unwound through the flame retardant layer pay-off frame 11, passes through the guide positioning piece 8, passes through three sets of forming wheels 9, and is introduced into the aircraft mold 10 to merge with the physical foaming cable core;

[0052] At the same time, the copper tape with the radiation slots 31 punched is unwound by a tension-free outer conductor active unwound rack 6. The unwound speed is controlled by an induction controller. The unwound speed is determined by the production speed and is generally 8 to 10 m / min. The copper tape with the radiation slots 31 punched is passed through a tape storage box 7, a guide positioning member 8, and three sets of forming wheels 9 to be introduced into an aircraft mold 10. Since the outer conductor 3 and the flame retardant layer 2 are longitudinally wrapped at the same time, in this step, the flame retardant layer 2 is longitudinally wrapped on the outside of the physical foam cable core (the longitudinal wrapping width is 20-60 mm) and the outer conductor 3 is longitudinally wrapped on the outside of the flame retardant layer 2 in a circular shape.

[0053] 3) The semi-finished product obtained in step 2) is sized by a sizing die 13 and fed into an extruder 14 via a guide wheel to be coated with polyethylene to form a sheath 1. The molten polyethylene is extruded from the extruder head by the extruder 14 at a temperature of 200-220° C. After the sheath 1 is formed, the obtained leaky cable is cooled in sections, first by cooling in hot water at 32-36° C. and then by cooling in a cold water tank at 20-24° C. The leaky cable is cooled to room temperature, printed with a label, and then fed to a main traction machine, where it is pulled onto a take-up reel and taken up on the reel.

[0054] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A flame retardant leaky cable, characterized in that: It includes a sheath, an outer conductor, an insulating layer and an inner conductor arranged in sequence from the outside to the inside, a flame retardant layer is longitudinally wrapped between the sheath and the outer conductor or between the outer conductor and the insulating layer, the flame retardant layer is a mica tape or PTFE, a plurality of radiation slots are arranged on the outer conductor, and the inner conductor is a spiral copper tube or a smooth copper tube; When the flame retardant layer is longitudinally wrapped between the sheath and the outer conductor, it only covers the radiation slots.

2. A flame-retardant leaky cable according to claim 1, characterized in that: The radiation slot has a slot length of 10-30 mm and a slot width of 2-4 mm.

3. A flame-retardant leaky cable according to claim 1 or 2, characterized in that: The angle between the radiation slot and the central axis of the leaky cable is 10-30°.

4. A flame-retardant leaky cable according to claim 1 or 2, characterized in that: The radiation slot is in a straight line or a U shape.

5. The flame-retardant leaky cable according to claim 1, characterized in that: When the flame retardant layer is longitudinally wrapped between the sheath and the outer conductor, a water blocking layer is arranged between the sheath and the flame retardant layer, and the outer portion of the water blocking layer is evenly coated with a rat and ant proof ointment layer.

6. A flame retardant leaky cable according to claim 5, characterized in that: The thickness of the rat and ant proof ointment layer is 0.5-3 mm.

7. The flame-retardant leaky cable according to claim 1, characterized in that: The thickness of the sheath is 1.4±0.2 mm or 1.9±0.2 mm; the thickness of the flame retardant layer is 0.13±0.01 mm.

8. The flame-retardant leaky cable according to claim 1, characterized in that: The thickness of the outer conductor is 0.075 mm-0.09 mm; the thickness of the inner conductor is 0.2 mm-0.45 mm.

9. A method for producing a flame-retardant leaky cable, characterized in that: The flame-retardant leaky cable comprises a sheath, an outer conductor, an insulating layer and an inner conductor arranged in sequence from the outside to the inside, a flame-retardant layer is longitudinally wrapped between the sheath and the outer conductor, the flame-retardant layer is a mica tape or PTFE, a plurality of radiation slots are arranged on the outer conductor, the flame-retardant layer only covers the radiation slots, and the inner conductor is a spiral copper tube or a smooth copper tube; the method comprises the following steps: 1) The copper tape with the radiation slots punched is unwound by a tension-free outer conductor active unwinding rack, and the unwinding speed is controlled by an induction controller. The unwinding speed is determined by the production speed and is 8-10 m / min. The copper tape with the radiation slots punched is passed through a tape storage box, a guide positioning piece, three sets of molding wheels, and then through an airplane mold to be longitudinally wrapped into a circle, ensuring that the leakage part of the copper tape with the radiation slots punched is subjected to the minimum force, ensuring the formation, thereby ensuring that the slots are not subjected to force; the mica tape or PTFE is unwound by a flame retardant layer unwinding rack, and then through a tape storage box, a guide positioning piece, three sets of molding wheels, and then through an airplane mold to be longitudinally wrapped on the outside of the outer conductor 3, the longitudinal wrapping width is 20-60 mm, and the outer conductor and the flame retardant layer are longitudinally wrapped at the same time; 2) The physical foam cable core composed of the inner conductor and the insulation layer is introduced into the aircraft mold by constant tension traction through the cable core active pay-off frame. The constant tension traction force is 70-90N, and it is combined with the initially formed outer conductor with a flame retardant layer, and the outer conductor with a flame retardant layer is coated on the periphery of the physical foam cable core; 3) Subsequently, the semi-finished product obtained in step 2) is sized by a sizing die; if a water-blocking layer is required, the water-blocking layer is directly wrapped around the outside of the flame-retardant layer, and then a rat-ant-proof ointment layer is applied before proceeding to step 4); 4) The semi-finished product obtained in step 3) is sent to an extruder through a guide wheel to be coated with a sheath. The molten polyethylene is extruded from the extruder head through the extruder. The extrusion temperature is controlled at 200-220° C. After the sheath is formed, the obtained leaky cable is cooled in sections, first cooled by hot water at 32-36° C., and then cooled in a cold water tank at 20-24° C. The leaky cable is cooled to room temperature, printed with a code, and then sent to a main traction machine, where it is pulled onto a take-up drum and the cable is taken up on the drum.

10. A method for producing a flame-retardant leaky cable, characterized in that: The flame-retardant leaky cable comprises a sheath, an outer conductor, an insulating layer and an inner conductor arranged in sequence from the outside to the inside, a flame-retardant layer is longitudinally wrapped between the outer conductor and the insulating layer, the flame-retardant layer is a mica tape or PTFE, a plurality of radiation slots are arranged on the outer conductor, and the inner conductor is a spiral copper tube or a smooth copper tube; the method comprises the following steps: 1) The physical foamed cable core consisting of an inner conductor and an insulating layer is introduced into the aircraft model through a cable core active pay-off frame by constant tension traction, and the constant tension traction force is 70-90N; 2) The mica tape or PTFE is unwound through the flame retardant layer pay-off frame, passed through the guide positioning piece, passed through three sets of molding wheels, introduced into the aircraft model, and merged with the physical foaming cable core; At the same time, the copper strip with the radiation slots punched is unwound by a tension-free outer conductor active unwinding rack, and the unwinding speed is controlled by an induction controller. The unwinding speed is determined by the production speed and is 8 to 10 m / min. The copper strip with the radiation slots punched is passed through a tape storage box, a guide positioning piece, and three sets of forming wheels, and is introduced into the aircraft model. The outer conductor and the flame retardant layer are longitudinally wrapped at the same time. 3) The semi-finished product obtained in step 2) is sized by a sizing die, and is sent to an extruder through a guide wheel to be coated with a sheath. The molten polyethylene is extruded from the extruder head by the extruder, and the extrusion temperature is controlled at 200-220° C. After the sheath is formed, the obtained leaky cable is cooled in sections, first cooled by hot water at 32-36° C., and then cooled in a cold water tank at 20-24° C. The leaky cable is cooled to room temperature, printed with a label, and then sent to a main traction machine, where it is pulled onto a take-up drum and the cable is taken up on the drum.

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