Cable with flame-retardant structure

Abstract

The present application relates to a kind of cable with flame-retardant structure, including conductor, insulating layer, filling layer, armoring and sheath;The insulating layer is arranged on the surface of conductor, and multiple conductor circumferential array arrangement;The filling layer is ceramic fiber, and uniformly distributed;The liquid outlet hose of cleaning brush is in contact with armored cable, when armored cable passes through connecting pipe, it can drive cleaning brush to rotate under the action of friction, since liquid outlet hose is blocked when it is in contact with armored cable, that is, it cannot discharge droplet after contact, that is, it cannot continuously clean armored cable in stationary state, therefore, the cleaning brush rotated by friction force can continuously contact armored cable with multiple cleaning brushes, solve the problem that liquid cannot continuously wet armored cable due to pressure effect, and it is not necessary to use external driving device to drive cleaning brush to rotate, only the effect brought by armored cable movement can be used.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a cable with a flame-retardant structure. Background Technology

[0002] Cables are a medium used for long-distance power transmission, and they consist of a sheath, a filling layer, and a conductor.

[0003] Cables have a wide range of uses, and when transmitting power over long distances, they need to be erected in the air via utility poles. However, when cables are erected in the air, if a short circuit occurs at the terminals, it can cause the contact points between the cable and the terminals to become hot and catch fire. Because they are erected in the air, it is not possible to effectively extinguish a fire caused by a cable over a high temperature. In the prior art, the outer sheath of the cable is often made by heating and extruding polyethylene material. Polyethylene is flammable. After generating high temperature and local fire, it will directly ignite the entire cable, which will have a significant impact on high voltage power transmission. Moreover, the replacement cost is high. Therefore, this invention proposes a cable with a flame-retardant structure. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the limitations of the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides a cable with a flame-retardant structure, including a conductor, an insulation layer, a filler layer, an armor, and a sheath; the insulation layer is arranged on the surface of the conductor, and multiple conductors are arranged in a circumferential array; the filler layer is ceramic fiber and is uniformly distributed; the armor is wrapped around the outside of the filler layer and located inside the sheath; the armor is made of steel tape, and the sheath is made of modified polyethylene. The modified polyethylene is produced by mixing an intumescent flame retardant with polyethylene in a certain mass ratio and then heating and extruding.

[0006] In one embodiment of the present invention, the intumescent flame retardant is composed of one or more of borate, polyamide, ammonium polyphosphate, starch, and cyclohexanehexol.

[0007] In one embodiment of the present invention, the preparation of the modified polyethylene includes the following steps: S1: Prepare intumescent flame retardant and polyethylene according to a certain mass ratio, and mix them evenly in a high-speed mixer; S2: The uniformly mixed material is poured into a co-rotating extruder, extruded under certain conditions, and then water-cooled and granulated to obtain modified polyethylene. In S2, the conditions include: the extruder screw speed is controlled at 200 r / min; the temperature is controlled within the range of 155-170℃.

[0008] In one embodiment of the present invention, the modified polyethylene is wrapped around the armor, comprising the following steps: pouring the prepared modified polyethylene into an extruder, heating and extruding it under certain conditions, and attaching it to the surface of the armored cable arranged perpendicularly to the extruder. The extruder end is connected to a contact cylinder via a flange, and an armored cable passes through the center of the contact cylinder.

[0009] In one embodiment of the present invention, the side wall of the contact cylinder is connected to a second connecting portion; and the second connecting portion is connected to the extrusion tube of the extruder; the end of the extrusion tube is provided with a first connecting portion, and the first connecting portion and the second connecting portion are fixedly connected by bolts; an inner cylinder is fixedly connected inside the contact cylinder, and a discharge channel is provided between the inner cylinder and the contact cylinder; the discharge channel is connected to the extrusion tube through the second connecting portion; parallel partitions are provided in the discharge channel, and the partitions are located in the middle of the second connecting portion.

[0010] In one embodiment of the present invention, a connecting pipe is embedded at one end of the contact cylinder; two cleaning brushes are rotatably connected inside the connecting pipe, and a liquid pipe is connected to the top of the cleaning brushes; the top of the liquid pipe passes through the connecting pipe; the cleaning brush is composed of multiple cleaning brushes, and the multiple cleaning brushes are arranged in a circumferential array; the multiple cleaning brushes facing inward contact the surface of the armored cable.

[0011] In one embodiment of the present invention, a closed cover is embedded at the end of the connecting tube away from the contact cylinder, and a connecting cover is fitted at the end of the closed cover away from the connecting tube; a plurality of clamps are movably connected between the connecting cover and the closed cover; a plurality of second sliding grooves are provided on the closed cover, and a plurality of first sliding grooves are correspondingly provided on the connecting cover; the first sliding grooves are configured as arc-shaped structures, and the second sliding grooves are configured as oval structures; the clamps include clamping plates and connecting plates; the bottom of the connecting plate is fixedly connected to the clamping plate, and the top of the connecting plate is slidably connected via an axis within the first and second sliding grooves; a turntable is fixedly connected to the outer end of the connecting cover.

[0012] In one embodiment of the present invention, a protective cover is fixedly connected inside the connecting pipe corresponding to the cleaning brush, and the protective cover has a semi-rugby-shaped structure; the cleaning brush is arranged inside the protective cover.

[0013] In one embodiment of the present invention, a limiting clamp is rotatably connected in the inner cylinder, and multiple limiting clamps are arranged in a circumferential array in the same plane; the limiting clamp is a T-shaped structure and has rounded corners at its ends; a slide rail is provided at one end of the limiting clamp near the side wall of the inner cylinder, and a ball bearing is rotatably connected in the slide rail.

[0014] In one embodiment of the present invention, two sets of limiting clamps are arranged equidistantly along the armored cable, and the two sets of limiting clamps are connected by a connecting arm; the connecting arm is made of elastic material, and the inner diameter of the end of the inner cylinder away from the connecting pipe is smaller than the inner diameter of the end of the inner cylinder close to the connecting pipe.

[0015] The technical solution of the present invention has the following advantages compared with the prior art: This invention also includes a cleaning brush. The liquid outlet hose of the cleaning brush contacts the armored cable. When the armored cable passes through the connecting pipe, the cleaning brush rotates under the action of friction. Since the liquid outlet hose gets blocked when it contacts the armored cable, meaning that no more liquid droplets can be discharged after contact, it is impossible to continuously clean the armored cable in a static state. Therefore, the cleaning brush that rotates by friction can use multiple cleaning brushes to continuously contact the armored cable, solving the problem that the liquid cannot be continuously discharged to wet the armored cable due to pressure. Moreover, there is no need to use an external drive device to drive the cleaning brush to rotate; the effect brought about by the movement of the armored cable is sufficient. This invention incorporates a cleaning brush inside the connecting pipe. To ensure the axis of the armored cable coincides with the axis of the connecting pipe, a closed cover is installed at one end of the connecting pipe. The clamp between the closed cover and the connecting cover can clamp and limit the armored cable, ensuring that the axis of the armored cable passing through the contact cylinder always coincides with the axis of the connecting pipe and the contact cylinder. This allows for cleaning and subsequent uniform adhesion of modified polyethylene. Furthermore, the arrangement of the clamp can limit the armored cable of different sizes, demonstrating strong adaptability. This invention arranges two sets of limiting clamps at equal intervals along the trajectory of the armored cable. Utilizing the connecting arms between the two sets of limiting clamps and the gradually decreasing inner diameter of the inner cylinder, the limiting clamps located away from the connecting pipe end can be moved to the end with the smaller inner diameter of the inner cylinder during the movement of the armored cable. At this time, under the action of the elastic connecting arms, the limiting clamps gradually approach the armored cable and, without affecting its passage, make it coincide with the axis of the connecting pipe, which is beneficial to maintaining the adhesion of the molten modified polyethylene. Attached Figure Description

[0016] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] Figure 1 This is a perspective view of the modified polyethylene and armored cable attachment device in this invention; Figure 2 This is a partial perspective view of the modified polyethylene and armored cable attachment device in this invention; Figure 3 This is a first cross-sectional perspective view of the modified polyethylene and armored cable attachment device in this invention; Figure 4 This is a second cross-sectional perspective view of the modified polyethylene and armored cable attachment device in this invention; Figure 5 This is a perspective view of the connecting pipe in this invention; Figure 6 This is a perspective view of the connecting pipe and the limiting clamp in this invention; Explanation of reference numerals in the accompanying drawings: 1. Extrusion tube; 11. First connecting part; 2. Contact cylinder; 21. Second connecting part; 22. Baffle plate; 23. Discharge channel; 24. Inner cylinder; 3. Connecting pipe; 31. Closing cover; 32. Connecting cover; 321. First chute; 33. Turntable; 34. Liquid pipeline; 35. Cleaning brush; 36. Limiting clamp; 361. Ball bearing; 362. Connecting arm; 37. Clamp; 38. Second chute; 4. Armored cable. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0019] Reference Figures 1-6 As shown, the present invention provides a cable with a flame-retardant structure, including a conductor, an insulation layer, a filler layer, an armor, and a sheath; the insulation layer is arranged on the surface of the conductor, and multiple conductors are arranged in a circumferential array; the filler layer is ceramic fiber and is uniformly distributed; the armor is wrapped around the outside of the filler layer and located inside the sheath; the armor is made of steel tape, and the sheath is made of modified polyethylene. The modified polyethylene is produced by mixing an intumescent flame retardant with polyethylene in a certain mass ratio and then heating and extruding.

[0020] In one embodiment of the present invention, the intumescent flame retardant is composed of one or more of borate, polyamide, ammonium polyphosphate, starch, and cyclohexanehexol.

[0021] In one embodiment of the present invention, the preparation of the modified polyethylene includes the following steps: S1: Prepare intumescent flame retardant and polyethylene according to a certain mass ratio, and mix them evenly in a high-speed mixer; S2: The uniformly mixed material is poured into a co-rotating extruder, extruded under certain conditions, and then water-cooled and granulated to obtain modified polyethylene. In S2, the conditions include: the extruder screw speed is controlled at 200 r / min; the temperature is controlled within the range of 155-170℃.

[0022] Specifically, in this scheme, when preparing modified polyethylene, different mass ratios of intumescent flame retardant and polyethylene are selected, and the five temperatures are controlled at 155℃, 160℃, 165℃, 170℃ and 165℃ respectively to prepare five kinds of modified polyethylene particles. Five types of modified polyethylene granules prepared under controlled temperature conditions were subjected to thermal stability tests to determine the optimal temperature. Specifically, the tests included: Thermogravimetric analysis (TG) was performed at a heating rate of 10℃ / min. The residual mass of modified polyethylene (M1) was subtracted from the residual mass of pure polyethylene (M2) at the same temperature to obtain the residual mass difference A between polyethylene with different intumescent flame retardant contents and pure polyethylene. The difference curve of residual mass difference was plotted according to the temperature value. The thermal stability effect OSE of modified polyethylene relative to pure polyethylene was expressed by calculus. The value of OSE expresses the change in thermal stability of modified polyethylene relative to pure polyethylene in this temperature range. If the value is positive, it indicates that the thermal stability is improved. If the value is negative, it indicates that the thermal stability is reduced. (1) (2); Where Te represents the initial temperature, To represents the final temperature, and dT represents the derivative with respect to T; Test results show that when 20% of intumescent flame retardant is added, the flame retardant performance of modified polyethylene is improved and the combustion rating is enhanced. Actual experiments have confirmed that when cable sheaths made of modified polyethylene are burned, gas is generated in the combustion zone, and the gas continuously bubbles outward from the melt, forming a black carbon layer that coats the surface of the sheath, causing the flame to gradually weaken until it is extinguished.

[0023] like Figure 1 As shown, in this embodiment, the modified polyethylene is wrapped around the armor, which includes the following steps: the prepared modified polyethylene is poured into an extruder, heated and extruded under certain conditions, and attached to the surface of the armored cable 4 arranged perpendicularly to the extruder. The extruder end is connected to a contact cylinder 2 via a flange, and the armored cable 4 passes through the center of the contact cylinder 2. Specifically, the contact cylinder 2 and the extruder are arranged perpendicularly. The extruder heats the modified polyethylene and then extrudes the molten modified polyethylene into the contact cylinder 2. The armored cable 4 passing through the contact cylinder 2 will come into contact with the molten modified polyethylene at the outlet end of the contact cylinder 2 and adhere to the armored cable 4 to form a cable sheath.

[0024] like Figure 2As shown, in this embodiment, in one embodiment of the present invention, the side wall of the contact cylinder 2 is connected to a second connecting part 21; and the second connecting part 21 is connected to the extrusion tube 1 of the extruder; the end of the extrusion tube 1 is provided with a first connecting part 11, and the first connecting part 11 and the second connecting part 21 are fixedly connected by bolts; as described above, the end of the extruder is provided with an extrusion tube 1, which is connected to the contact cylinder 2. Specifically, the end of the extrusion tube 1 is provided with a first connecting part 11, and the side wall of the contact cylinder 2 is provided with a second connecting part 21. The first connecting part 11 and the second connecting part 21 are connected by a flange and bolts. With the help of a sealing gasket, molten modified polyethylene can enter the contact cylinder. The contact cylinder 2 is then attached to the surface of the armored cable 4; an inner cylinder 24 is fixedly connected inside the contact cylinder 2, and a discharge channel 23 is provided between the inner cylinder 24 and the contact cylinder 2; the discharge channel 23 is connected to the extrusion tube 1 via the second connecting part 21; parallel partitions 22 are provided inside the discharge channel 23, and the partitions 22 are located in the middle of the second connecting part 21; specifically, molten modified polyethylene enters the contact cylinder 2 through the second connecting part 21 and is located in the discharge channel 23 between the inner cylinder 24 and the contact cylinder 2, and is evenly distributed in the discharge channel 23 under the action of the partitions 22, so that it can be evenly attached to the upper and lower sides of the armored cable 4 during extrusion.

[0025] like Figures 2-3 As shown, in this embodiment, a connecting pipe 3 is embedded at one end of the contact cylinder 2; two cleaning brushes 35 are rotatably connected inside the connecting pipe 3, and the top of the cleaning brushes 35 is connected to a liquid pipe 34; since the surface of the armored cable 4 must be kept clean when it comes into contact with the modified polyethylene, two cleaning brushes 35 are provided inside the connecting pipe 3 to clean the armored cable 4. When the armored cable 4 moves smoothly in the connecting pipe 3 and the contact cylinder 2, it can drive the cleaning brushes 35 inside the connecting pipe 3 to rotate. Liquid is filled into the cleaning brushes 35 through the liquid pipe 34, which can wash the surface of the armored cable 4, cleaning the dust on its surface. After that, it enters the contact cylinder 2 for a short drying time, then comes into contact with the molten modified polyethylene to form a cable sheath; the top of the liquid pipe 34 passes through the connecting pipe 3; the cleaning brushes 35 are composed of multiple cleaning brushes, and the multiple cleaning brushes are arranged in a circumferential array; the multiple cleaning brushes facing inward contact the surface of the armored cable 4; as shown in the attached figure. Figure 3As shown, the cleaning brush 35 includes multiple cleaning brushes, and the liquid outlet hose of the cleaning brush is in contact with the armored cable 4. When the armored cable 4 passes through the connecting pipe 3, it will drive the cleaning brush 35 to rotate under the action of friction. Since the liquid outlet hose will be blocked when it contacts the armored cable 4, that is, no more liquid droplets can be discharged after contact, and the armored cable 4 cannot be continuously cleaned in a static state. Therefore, the cleaning brush 35, which rotates by friction, can use multiple cleaning brushes to continuously contact the armored cable 4, solving the problem that the liquid cannot be continuously discharged to wet the armored cable 4 due to pressure. Moreover, there is no need to use an external drive device to drive the cleaning brush 35 to rotate; the effect brought about by the movement of the armored cable 4 is sufficient.

[0026] like Figures 4-5 As shown, in this embodiment, a closed cover 31 is embedded at the end of the connecting tube 3 away from the contact cylinder 2, and a connecting cover 32 is fitted at the end of the closed cover 31 away from the connecting tube 3. Multiple clamps 37 are movably connected between the connecting cover 32 and the closed cover 31. Since a cleaning brush 35 is installed inside the connecting tube 3, it is necessary to keep the axis of the armored cable 4 aligned with the axis of the connecting tube 3. Therefore, a closed cover 31 is installed at one end of the connecting tube 3. The clamps 37 between the closed cover 31 and the connecting cover 32 can clamp and limit the armored cable 4, ensuring that the axis of the armored cable 4 passing through the contact cylinder 2 is always aligned with the axes of the connecting tube 3 and the contact cylinder 2. This allows for cleaning and subsequent uniform adhesion of modified polyethylene. Furthermore, the arrangement of the clamps 37 allows for limiting the size of armored cables 4, providing strong adaptability. Multiple second clamps are provided on the closed cover 31. The connecting cover 32 has a sliding groove 38, and a plurality of first sliding grooves 321 are correspondingly provided on the connecting cover 32. The first sliding groove 321 is set with an arc-shaped structure, and the second sliding groove 38 is set with an oval structure. The clamp 37 includes a clamping plate and a connecting plate. The bottom of the connecting plate is fixedly connected to the clamping plate, and the top of the connecting plate is slidably connected to the first sliding groove 321 and the second sliding groove 38 via an axis. The outer end of the connecting cover 32 is fixedly connected to a turntable 33. The turntable 33 drives the connecting cover 32 to rotate, and through the first sliding groove 321 of the connecting cover 32, drives the connecting plate in the second sliding groove 38 to move smoothly. This can limit the radial movement of multiple clamping plates between the connecting cover 32 and the closed cover 31. Under the limiting effect, the multiple clamping plates cooperate with the first sliding groove 321 and the second sliding groove 38 to move synchronously, which can limit the armored cables 4 of different sizes and keep the axis of the armored cable 4 coincide with the axis of the connecting tube 3.

[0027] In one embodiment of the present invention, a protective cover is fixedly connected inside the connecting pipe 3 corresponding to the cleaning brush 35, and the protective cover has a semi-oval-shaped structure; the cleaning brush 35 is arranged inside the protective cover. Since the cleaning brush 35 is mainly used to remove and wash the dust on the armored cable 4, in order to prevent the cleaning brush on the cleaning brush 35 from discharging droplets and causing waste when it does not contact the armored cable 4, a protective cover is set so that the cleaning brush and the protective cover have a squeezing effect, thereby avoiding the cleaning brush that does not contact the armored cable 4 from discharging droplets and causing waste.

[0028] like Figure 6 As shown, in this embodiment, a limiting clamp 36 is rotatably connected in the inner cylinder 24, and multiple limiting clamps 36 are arranged in a circumferential array in the same plane; the limiting clamp 36 has a T-shaped structure and rounded corners at the ends; a slide rail is provided at one end of the limiting clamp 36 near the side wall of the inner cylinder 24, and a ball bearing 361 is rolled inside the slide rail; the armored cable 4, after being cleaned, enters the inner cylinder 24, and its surface contains moisture, which will affect the adhesion of the molten modified polyethylene. Therefore, the armored cable 4 needs to be dried in the inner cylinder 24, and the armored cable 4 needs to be straightened at the same time. The armored cable 4 entering the inner cylinder 24 is supported by a limiting clamp 36. At the same time, an electric heating wire is installed in the side wall of the inner cylinder 24 to heat and dry the armored cable 4 as it moves in the inner cylinder 24, removing the moisture from the surface of the armored cable 4 and maintaining its surface temperature, which is beneficial for the adhesion of the molten modified polyethylene later. The rounded corners arranged at the ends of the limiting clamp 36 can prevent the surface of the armored cable 4 from being scratched when it comes into contact with it. Meanwhile, the ball bearings 361 set at the ends of the limiting clamp 36 facilitate the displacement of the limiting clamp 36 in the inner cylinder 24.

[0029] In one embodiment of the present invention, two sets of limiting clamps 36 are arranged equidistantly along the armored cable 4, and the two sets of limiting clamps 36 are connected by a connecting arm 362. The connecting arm 362 is made of elastic material, and the inner diameter of the inner cylinder 24 at the end away from the connecting pipe 3 is smaller than the inner diameter of the end of the inner cylinder 24 closer to the connecting pipe 3. By arranging two sets of limiting clamps 36 equidistantly along the forward trajectory of the armored cable 4, and utilizing the connecting arm 362 between the two sets of limiting clamps 36, as well as the characteristic of the inner diameter of the inner cylinder 24 gradually decreasing, during the movement of the armored cable 4, the set of limiting clamps 36 at the end away from the connecting pipe 3 can be moved to the end of the inner cylinder 24 with the smaller inner diameter. At this time, under the action of the elastic material connecting arm 362, the set of limiting clamps 36 gradually approaches the armored cable 4, and on the basis of not affecting its passage, it is made to coincide with the axis of the connecting pipe 3, which is beneficial to maintaining the adhesion of the molten modified polyethylene.

[0030] Working principle: Since the outer sheath of cables is usually made by heating and extruding polyethylene material, and polyethylene is flammable, after generating high temperature and local fire, it will directly ignite the entire cable, which will have a significant impact on high-voltage power transmission and the replacement cost will be high. This invention prepares modified polyethylene based on traditional polyethylene material. By mixing in an intumescent flame retardant, the thermal stability and fire resistance of the modified polyethylene material can be improved. Specifically, in the preparation of this flame-retardant cable, the extrusion tube 1 of the extruder and the contact cylinder 2 are arranged perpendicularly and crosswise. The modified polyethylene is heated by the extruder and then the molten modified polyethylene is extruded into the contact cylinder 2. The armored cable 4 passing through the contact cylinder 2 will come into contact with the molten modified polyethylene at the outlet end of the contact cylinder 2 and adhere to the armored cable 4 to form the cable sheath. In this process, since the surface of the armored cable 4 must remain clean when in contact with the modified polyethylene, two cleaning brushes 35 are installed inside the connecting pipe 3 to ensure thorough cleaning. As the armored cable 4 moves smoothly through the connecting pipe 3 and the contact cylinder 2, the cleaning brushes 35 rotate. Liquid is introduced into the cleaning brushes 35 via liquid pipes 34, which washes the surface of the armored cable 4, removing surface dust. After a brief drying process inside the contact cylinder 2, the cable comes into contact with the molten modified polyethylene, forming a cable sheath. The cleaning brushes 35 include multiple cleaning bristles. The liquid outlet hose of the cleaning brush contacts the armored cable 4. When the armored cable 4 passes through the connecting pipe 3, it will drive the cleaning brush 35 to rotate under the action of friction. Since the liquid outlet hose will be blocked when it contacts the armored cable 4, that is, no more liquid droplets can be discharged after contact, and the armored cable 4 cannot be continuously cleaned in a static state. Therefore, the cleaning brush 35, which rotates by friction, can use multiple cleaning brushes to continuously contact the armored cable 4, solving the problem that the liquid cannot be continuously discharged to wet the armored cable 4 due to pressure. Moreover, there is no need to use an external drive device to drive the cleaning brush 35 to rotate; the effect brought about by the movement of the armored cable 4 is sufficient.

[0031] Furthermore, the turntable 33 drives the connecting cover 32 to rotate, and through the first slide groove 321 of the connecting cover 32, the connecting plate in the second slide groove 38 is driven to move smoothly. This restricts the radial movement of multiple clamping plates between the connecting cover 32 and the closing cover 31. Under the restriction, the multiple clamping plates cooperate with the first slide groove 321 and the second slide groove 38 to move synchronously, which limits the armored cables 4 of different sizes and keeps the axis of the armored cables 4 coincident with the axis of the connecting tube 3. It can limit the armored cables 4 of different sizes and has strong adaptability. Finally, the armored cable 4, after cleaning, enters the inner cylinder 24. Its surface contains moisture, which can affect the adhesion of the molten modified polyethylene. Therefore, the armored cable 4 needs to be dried and straightened within the inner cylinder 24. A limiting clamp 36 is used to support the armored cable 4 as it enters the inner cylinder 24. Heating wires are installed inside the side wall of the inner cylinder 24 to heat and dry the armored cable 4 as it moves within the cylinder, removing surface moisture and maintaining its surface temperature, which is beneficial for the subsequent adhesion of the molten modified polyethylene. The rounded corners at the ends of the limiting clamp 36 prevent scratching the surface of the armored cable 4 when it comes into contact with the clamp. Meanwhile, the ball bearings 361 at the end of the limiting clamp 36 facilitate the displacement of the limiting clamp 36 within the inner cylinder 24. Specifically, two sets of limiting clamps 36 are arranged at equal intervals along the forward trajectory of the armored cable 4. Utilizing the connecting arm 362 between the two sets of limiting clamps 36 and the gradually decreasing inner diameter of the inner cylinder 24, the limiting clamp 36 at the end away from the connecting pipe 3 can be moved to the end with the smaller inner diameter in the inner cylinder 24 during the movement of the armored cable 4. At this time, under the action of the elastic connecting arm 362, the limiting clamp 36 gradually approaches the armored cable 4 and, without affecting its passage, makes it coincide with the axis of the connecting pipe 3, which is beneficial for maintaining the adhesion of the molten modified polyethylene.

[0032] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An extruder for preparing cables with flame-retardant structures, characterized in that: The flame-retardant cable includes a conductor, an insulation layer, a filler layer, an armor, and a sheath; the insulation layer is arranged on the surface of the conductor, and multiple conductors are arranged in a circumferential array; the filler layer is ceramic fiber and is evenly distributed; the armor is wrapped around the outside of the filler layer and located inside the sheath; the armor is made of steel tape, and the sheath is made of modified polyethylene. The modified polyethylene is produced by mixing an intumescent flame retardant with polyethylene in a certain mass ratio and then heating and extruding the mixture. The preparation of the modified polyethylene includes the following steps: S1: Prepare intumescent flame retardant and polyethylene according to a certain mass ratio, and mix them evenly in a high-speed mixer; S2: The uniformly mixed material is poured into a co-rotating extruder, extruded under certain conditions, and then water-cooled and granulated to obtain modified polyethylene. In S2, the conditions include: the extruder screw speed is controlled at 200 r / min; the temperature is controlled within the range of 155-170℃. The modified polyethylene is wrapped around the armor, including the following steps: the prepared modified polyethylene is poured into an extruder, heated and extruded under certain conditions, and attached to the surface of the armored cable (4) arranged perpendicularly to the extruder. The extruder end is connected to a contact cylinder (2) via a flange, and the armored cable (4) passes through the center of the contact cylinder (2). The side wall of the contact cylinder (2) is connected to a second connecting part (21); and the second connecting part (21) is connected to the extrusion tube (1) of the extruder; the end of the extrusion tube (1) is provided with a first connecting part (11), and the first connecting part (11) and the second connecting part (21) are fixedly connected by bolts; an inner cylinder (24) is fixedly connected inside the contact cylinder (2), and a discharge channel (23) is provided between the inner cylinder (24) and the contact cylinder (2); the discharge channel (23) is connected to the extrusion tube (1) through the second connecting part (21); parallel partitions (22) are provided inside the discharge channel (23), and the partitions (22) are located in the middle of the second connecting part (21); One end of the contact cylinder (2) is embedded with a connecting pipe (3); two cleaning brushes (35) are rotatably connected inside the connecting pipe (3), and the top of the cleaning brushes (35) is connected to a liquid pipe (34); the top of the liquid pipe (34) passes through the connecting pipe (3); the cleaning brushes (35) are composed of multiple cleaning brushes, and the multiple cleaning brushes are arranged in a circumferential array; the multiple cleaning brushes facing inward are in contact with the surface of the armored cable (4); The cleaning brush (35) includes multiple cleaning brushes, and the liquid outlet hose of the cleaning brush is in contact with the armored cable (4). When the armored cable (4) passes through the connecting pipe (3), it will drive the cleaning brush (35) to rotate under the action of friction. Since the liquid outlet hose will be blocked when it contacts the armored cable (4), it will be unable to discharge liquid droplets after contact, and thus it will be unable to continuously clean the armored cable (4) in a static state.

2. The extruder for preparing cables with flame-retardant structures according to claim 1, characterized in that: The intumescent flame retardant is composed of one or more of the following: borate, polyamide, ammonium polyphosphate, starch, and cyclohexanehexol.

3. The extruder for preparing cables with flame-retardant structures according to claim 1, characterized in that: The end of the connecting tube (3) away from the contact cylinder (2) is embedded with a closed cover (31), and the end of the closed cover (31) away from the connecting tube (3) is fitted with a connecting cover (32); a plurality of clamps (37) are movably connected between the connecting cover (32) and the closed cover (31); a plurality of second sliding grooves (38) are provided on the closed cover (31), and a plurality of first sliding grooves (321) are correspondingly provided on the connecting cover (32); the first sliding groove (321) is set as an arc-shaped structure, and the second sliding groove (38) is set as an oval structure; the clamp (37) includes a clamping plate and a connecting plate; the bottom of the connecting plate is fixedly connected to the clamping plate, and the top of the connecting plate is slidably connected to the first sliding groove (321) and the second sliding groove (38) via an axis; a turntable (33) is fixedly connected to the outer end of the connecting cover (32).

4. An extruder for preparing cables with flame-retardant structures according to claim 1, characterized in that: The connecting pipe (3) has a protective cover fixed inside corresponding to the cleaning brush (35), and the protective cover has a semi-oval-shaped structure; the cleaning brush (35) is arranged inside the protective cover.

5. An extruder for preparing cables with flame-retardant structures according to claim 1, characterized in that: The inner cylinder (24) is rotatably connected to a limiting clamp (36), and multiple limiting clamps (36) are arranged in a circumferential array in the same plane; the limiting clamp (36) is a T-shaped structure and has rounded corners at the ends; the end of the limiting clamp (36) near the side wall of the inner cylinder (24) is provided with a slide rail, and a ball bearing (361) is rotatably connected in the slide rail.

6. An extruder for preparing cables with flame-retardant structures according to claim 5, characterized in that: Two sets of limiting clamps (36) are arranged at equal intervals along the armored cable (4), and the two sets of limiting clamps (36) are connected through a connecting arm (362); the connecting arm (362) is made of elastic material, and the inner diameter of the end of the inner cylinder (24) away from the connecting pipe (3) is smaller than the inner diameter of the end of the inner cylinder (24) close to the connecting pipe (3).

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