A flame-retardant polyethylene sheathed cable and its production equipment

Abstract

The invention provides a flame-retardant polyethylene sheathed cable and production equipment thereof, relating to the technical field of cable production. The cable comprises a conductor cable core, which is wrapped with a flame-retardant polyethylene sheath containing a flame retardant. The flame retardant contains 60 parts of magnesium hydroxide based on 100 parts of a polyethylene matrix. A phase-change heat-conducting cavity is provided in the sheath to accommodate a 20wt% borax aqueous solution. Heat is dissipated by utilizing the phase-change endothermic-exothermic characteristics of desorption and condensation reflux of borax crystallization water. A heat-conducting thin wall in the cavity increases the heat dissipation area and provides a crystallization carrier. The production equipment comprises an extrusion die head, wherein the extrusion die core is spliced ​​by six groups of component die cores, and an injection cavity is provided between the die cores. One end of the extrusion die core is inserted into a heat-conducting cavity forming die, and the thin-wall forming groove thereof is extruded to form a heat-conducting thin wall. The cable improves high-temperature resistance and flame-retardant properties through a phase-change heat management system. The equipment achieves efficient production and ensures synchronization of solution filling and structural forming.

Description

Technical Field

[0001] The present invention relates to the technical field of cable production, in particular to a flame-retardant polyethylene sheathed cable and production equipment thereof. Background Art

[0002] With the acceleration of urbanization and the improvement of industrial automation, the application of cables in high-rise buildings, rail transit, new energy and other fields is becoming more and more intensive, which puts strict requirements on the flame retardant performance and thermal management capabilities of cables.

[0003] Traditional flame-retardant cables mainly rely on the addition of chemical flame retardants such as magnesium hydroxide and intumescent flame retardants to inhibit combustion through mechanisms such as endothermic decomposition and carbonization barrier, but there are the following technical bottlenecks: the heat absorption efficiency of chemical flame retardants at high temperatures gradually decreases with increasing temperature, and they cannot effectively cope with the continuous temperature increase caused by cable overload or external fire sources. The problem of "flame retardant but not heat dissipating" is prone to occur, resulting in heat accumulation and chain fires. At the same time, traditional cables improve thermal conductivity through sheath material modification, but metal fillers are easily oxidized and have poor compatibility with polyethylene, and can only conduct heat through solid-state heat, and cannot achieve phase change latent heat absorption. The heat dissipation effect is limited in local overheating scenarios. Summary of the Invention

[0004] The object of the present invention is to provide a flame-retardant polyethylene sheathed cable and a production device thereof, so as to solve the problem of limited heat dissipation effect of traditional flame-retardant cables in local overheating scenarios proposed in the above background.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is a flame retardant polyethylene sheathed cable and its production equipment, including: a conductor cable core, a flame retardant polyethylene sheath wrapped on the outside of the conductor cable core, a phase change heat conduction cavity is opened in the flame retardant polyethylene sheath, a phase change heat conduction cavity is injected with a phase change heat conduction solution, and the endothermic-exothermic characteristics of the phase change process of desorption and condensation reflux of borax crystal water in the phase change heat conduction solution are utilized to realize efficient heat dissipation and circulation during cable operation, and improve the high temperature resistance of the flame retardant sheath; a production equipment for preparing a flame retardant polyethylene sheathed cable includes an extrusion die head, an extrusion die core is provided in the extrusion die head, the extrusion die core is inserted into the extrusion die head from one end, and the extrusion die core is composed of six groups of split die cores spliced ​​together. The modular design of the split die core facilitates disassembly and maintenance of the equipment and adapts to the rapid replacement of cable core channels of different specifications. Two copper hoops are provided on the outside of the six groups of split cores for fixing. The hoop applies radial pressure to the split mold core through interference fit to ensure that the mold core splicing gap is tight, and at the same time achieves sealing between the extrusion mold core and the extrusion die head to prevent molten polyethylene from penetrating into the injection cavity. An injection cavity for the borax solution to pass through is provided between each two groups of split mold cores. The injection cavity is a transmission channel for the borax solution, and its distribution corresponds one-to-one with the injection port of the thermal conductivity cavity forming mold to ensure that the solution is evenly injected into each phase change thermal conductivity cavity. A cable core channel for the conductor cable core to pass through is provided in the center of the extrusion mold core. The cable core channel plays a positioning role for the conductor cable core to ensure that the cable core is centered in the sheath to avoid uneven heat dissipation caused by eccentricity; six groups of thermal conductivity cavity forming dies are inserted at one end of the extrusion mold core. The thermal conductivity cavity forming mold is a forming mold for the phase change thermal conductivity cavity. Its shape matches the phase change cavity structure of the inner wall of the sheath. An injection port is provided in the thermal conductivity cavity forming mold, and the injection port is connected to the injection cavity, which is the final outlet for the borax solution to be injected into the phase change thermal conductivity cavity.

[0006] Furthermore, a flame retardant is added to the flame retardant polyethylene sheath, and based on 100 parts of polyethylene matrix, 60 parts of magnesium hydroxide, 12.5 parts of ammonium polyphosphate, 5 parts of melamine, 7.5 parts of pentaerythritol and 5 parts of nano-montmorillonite are added.

[0007] Furthermore, the phase-change heat-conducting solution is a 20 wt% borax aqueous solution, to which 1 wt% sodium carboxymethyl cellulose is added as a thickener, and 5 wt% glycerol is added as an anti-evaporation agent.

[0008] Furthermore, dense thin-wall molding grooves are provided on the outer side of one end of the heat-conducting cavity molding die, and a heat-conducting thin wall is provided in the phase-change heat-conducting cavity. The thin-wall molding grooves extrude the molten polyethylene during the extrusion process, and a heat-conducting thin wall is simultaneously formed on the inner wall of the phase-change heat-conducting cavity. No subsequent processing is required, thereby improving production efficiency and ensuring the uniformity of the thin-wall structure.

[0009] Furthermore, an extrusion cavity is located between the extrusion core and the extrusion die head. This cavity serves as a temporary storage and pressurization channel for molten polyethylene, ensuring that the polyethylene uniformly coats the conductor cable core under high pressure. A polyethylene inlet is located on one side of the extrusion cavity, connected to a twin-screw extruder for introducing molten flame-retardant polyethylene raw material. An extrusion port is located at one end of the extrusion die head, serving as the sheath forming outlet. Here, the molten polyethylene is composited with the conductor cable core and, under the constraints of the thermal cavity forming die, forms a sheath structure with a phase-change thermal cavity.

[0010] Furthermore, a quantitative injection valve is provided at one end of the extrusion die head, and the quantitative injection valve is used to accurately control the injection amount of the borax solution to ensure synchronization with the sheath extrusion speed, and to avoid excessive or insufficient solution affecting the performance of the cable. A honeycomb piston cylinder and a circular partition are provided in the quantitative injection valve, and a solution introduction cavity is provided between the honeycomb piston cylinder and the circular partition. The solution introduction cavity temporarily stores the borax solution input from the solution introduction port, and provides a buffer for the liquid absorption process of the driving piston. A solution introduction port is provided on one side of the solution introduction cavity, and the solution introduction port is connected to the borax solution storage tank for continuous replenishment of the solution. A pressurized injection cavity is provided on the right side of the honeycomb piston cylinder, and the pressurized injection cavity performs secondary pressurization on the borax solution to ensure that the solution penetrates and fills the phase change heat conduction cavity when the polyethylene sheath has not yet fully solidified. A dispersed injection port is provided on the right side of the pressurized injection chamber, which is connected to the injection cavity to evenly distribute the pressurized solution to each injection cavity. A cable core passing tube runs through the quantitative injection valve. The cable core passing tube is a guide channel for the conductor cable core. Its inner diameter matches the cable core channel to ensure that the cable core passes through the equipment in a straight line to avoid deviation.

[0011] Furthermore, six groups of drive pistons are provided in the honeycomb piston cylinder. These six groups of drive pistons reciprocate synchronously, achieving quantitative suction and delivery of the solution through volume changes. The multi-piston design can reduce the volume flow fluctuation of a single piston and improve metering accuracy. A piston rod is fixedly connected to one end of the drive piston, and the piston rod passes through a circular partition. A tilting disk rotates in the quantitative injection valve. The tilting disk is the driving mechanism for the piston movement, and its tilt angle determines the piston stroke, thereby controlling the single injection volume. A sliding groove is provided on the tilting disk, and a sliding ball head is fixedly connected to one end of the piston rod. The sliding ball head is slidably connected to the sliding groove. The cooperation between the sliding ball head and the sliding groove converts the rotational motion of the tilting disk into linear reciprocating motion of the piston rod. The structure is compact and the transmission efficiency is high.

[0012] Furthermore, the piston rod is slidably connected to the circular partition through a sealing sleeve, and the sealing sleeve ensures the sealing performance of the piston rod during movement to prevent leakage of the solution.

[0013] Furthermore, a first one-way valve is provided within the drive piston to control the one-way flow of solution into the drive piston. The first one-way valve opens during aspiration and closes during discharge. A second one-way valve is provided at the right opening of the honeycomb piston cylinder to control the one-way flow of solution out of the honeycomb piston cylinder. The second one-way valve opens during discharge and closes during aspiration, working in conjunction with the first one-way valve to achieve directional delivery of solution.

[0014] Furthermore, a first gear is fixedly connected to one side of the swash plate. This first gear meshes with a second gear, which in turn meshes with a third gear. This three-stage gear transmission system reduces the speed of the drive motor and increases its torque, ensuring smooth rotation of the swash plate. The gear ratio also precisely controls the piston's movement frequency to match the sheath extrusion speed. A drive motor is housed within the metered injection valve, providing power for the entire metered injection system. Frequency conversion allows for adjustable injection rates to suit varying production conditions. The output shaft of the drive motor is fixedly connected to the third gear.

[0015] Compared with the existing technology, the beneficial effects of the present invention include: 1. The flame-retardant polyethylene sheathed cable and its production equipment proposed by the present invention, through a multi-stage phase change thermal management mechanism, utilizes the three-stage phase change process of borax decahydrate: initial dehydration at 32.4°C, complete dehydration at 60°C, and water vaporization at 100°C, to achieve gradient heat absorption from the initial stage of local overheating of the cable to the extreme high temperature scenario. The total phase change latent heat reaches 2350kJ / kg, which is significantly improved compared to traditional paraffin-based phase change materials, filling the gap in low-temperature response between 30-100°C. 2. The flame-retardant polyethylene sheathed cable and its production equipment proposed by the present invention, through structure-material collaborative design, utilizes a sheet-shaped heat-conducting thin wall integrally formed by a mold to provide a three-dimensional attachment surface for borax crystals. Combined with the hexagonal array layout of the phase change heat-conducting cavity and the capillary reflux network, the reflux rate of condensed water is increased, forming a "heat absorption-condensation-reflux" closed cycle that does not require external power. 3. The flame-retardant polyethylene sheathed cable and its production equipment proposed in the present invention combine the glassy protective layer generated by dehydrating borax with the magnesium hydroxide and intumescent flame retardant in the sheath through a triple synergistic flame-retardant barrier to reduce the flame spread rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 Schematically shows a cross-sectional structural diagram of a flame-retardant polyethylene sheathed cable proposed according to one embodiment of the present invention; Figure 2 The following schematically shows the appearance and structure of a production device for a flame-retardant polyethylene sheathed cable according to one embodiment of the present invention; Figure 3A schematic cross-sectional view of a production device for a flame-retardant polyethylene sheathed cable according to one embodiment of the present invention is shown; Figure 4 A schematic diagram of the structure of an extrusion die head of a flame-retardant polyethylene sheathed cable production device according to one embodiment of the present invention is shown; Figure 5 A schematic diagram of the structure of an extrusion die core of a flame-retardant polyethylene sheathed cable production device according to one embodiment of the present invention is shown; Figure 6 A schematic diagram of the side view of the structure of an extrusion die core of a flame-retardant polyethylene sheathed cable production equipment proposed in accordance with one embodiment of the present invention is shown; Figure 7 A schematic diagram of the structure of a heat-conducting cavity forming die of a flame-retardant polyethylene sheathed cable production equipment according to one embodiment of the present invention is shown; Figure 8 The schematic diagram of the structure of a quantitative injection valve of a production equipment for flame-retardant polyethylene sheathed cables proposed according to one embodiment of the present invention is shown.

[0017] Numbers in the figure: 1, conductor cable core; 2, flame retardant polyethylene sheath; 3, phase change heat conduction cavity; 4, heat conduction thin wall; 5, extrusion die; 501, extrusion cavity; 502, polyethylene injection port; 503, extrusion port; 6, extrusion core; 601, split core; 602, copper hoop; 603, injection cavity; 604, cable core channel; 7, heat conduction cavity molding die; 701, injection port; 702, thin wall molding groove; 8, quantitative injection valve; 9, honeycomb Piston cylinder; 901, driving piston; 902, piston rod; 903, tilting plate; 904, sliding groove; 905, sliding ball head; 906, first one-way valve; 907, second one-way valve; 10, circular partition; 11, solution inlet chamber; 12, solution inlet port; 13, pressurized injection chamber; 14, dispersion injection port; 15, first gear; 16, second gear; 17, third gear; 18, driving motor; 19, cable core passing tube. DETAILED DESCRIPTION

[0018] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0019] According to the embodiment of the present invention, Figure 1A flame-retardant polyethylene sheathed cable comprises a conductor cable core 1, which is wrapped with a flame-retardant polyethylene sheath 2. The flame-retardant polyethylene sheath 2 contains a flame retardant, which comprises 60 parts of magnesium hydroxide, 12.5 parts of ammonium polyphosphate, 5 parts of melamine, 7.5 parts of pentaerythritol, and 5 parts of nano-montmorillonite, based on 100 parts of polyethylene matrix.

[0020] A phase-change heat-conducting cavity 3 is provided in the flame-retardant polyethylene sheath 2. The phase-change heat-conducting cavity 3 is used to accommodate a phase-change heat-conducting solution. The heat-absorbing and heat-releasing characteristics of the phase-change heat-conducting solution during the desorption and condensation reflux of borax crystal water are utilized to achieve efficient heat dissipation and circulation during cable operation, thereby improving the high-temperature resistance of the flame-retardant sheath. The phase-change heat-conducting solution is a 20wt% borax aqueous solution, with 1wt% sodium carboxymethyl cellulose added as a thickener, and 5wt% glycerol added as an anti-evaporation agent.

[0021] The phase-change heat-conducting cavity 3 is provided with a heat-conducting thin wall 4, which is extruded by the thin-wall forming groove 702. Its densely distributed sheet structure can significantly increase the heat dissipation surface area of ​​the inner wall of the phase-change heat-conducting cavity 3, enhance the heat exchange efficiency between the borax solution and the sheath, and provide an attachment carrier for the crystallization of borax decahydrate. The borax solution in the phase-change heat-conducting cavity 3 crystallizes to form borax decahydrate at low temperature, i.e. , dehydration endothermic reaction at high temperature: The heat from cable operation or external fire source is absorbed by the latent heat of phase change, which suppresses the temperature rise of the sheath and delays combustion. The precipitated water vapor condenses and flows back through the phase change heat conduction cavity 3, forming a continuous thermal management system.

[0022] According to the embodiment of the present invention, Figure 2-Figure 8 Shown. A production device for flame-retardant polyethylene sheathed cables, including an extrusion die 5, an extrusion core 6 is provided in the extrusion die 5, the extrusion core 6 is inserted into the extrusion die 5 from one end, and an extrusion cavity 501 is provided between the extrusion core 6 and the extrusion die 5, the extrusion cavity 501 is a temporary storage and pressurization channel for molten polyethylene, ensuring that the polyethylene uniformly covers the conductor cable core 1 under high pressure. A polyethylene injection port 502 is provided on one side of the extrusion cavity 501, and the polyethylene injection port 502 is connected to a twin-screw extruder for introducing molten flame-retardant polyethylene raw materials. An extrusion port 503 is provided at one end of the extrusion die 5, and the extrusion port 503 is a sheath molding outlet, where the molten polyethylene is compounded with the conductor cable core 1, and a sheath structure with a phase-change heat-conducting cavity 3 is formed under the constraint of the heat-conducting cavity molding die 7.

[0023] The extrusion mold core 6 is composed of six groups of split mold cores 601 spliced ​​together. The modular design of the split mold core 601 facilitates the disassembly and maintenance of the equipment and adapts to the rapid replacement of cable core channels 604 of different specifications. Two copper hoops 602 are set on the outside of the six groups of split mold cores 601 for fixation. The copper hoops 602 exert radial pressure on the split mold core 601 through interference fit to ensure that the mold core splicing gap is tight, and at the same time, the seal between the extrusion mold core 6 and the extrusion die head 5 is achieved to prevent molten polyethylene from penetrating into the injection cavity 603. An injection cavity 603 for the passage of borax solution is provided between each two groups of split mold cores 601. The injection cavity 603 is a transmission channel for the borax solution. Its distribution corresponds one-to-one with the injection port 701 of the thermal cavity forming mold 7 to ensure that the solution is evenly injected into each phase change thermal cavity 3. A cable core channel 604 for the conductor cable core 1 to pass through is opened in the center of the extrusion die core 6. The cable core channel 604 positions the conductor cable core 1 to ensure that the cable core is centered in the sheath and avoid uneven heat dissipation caused by eccentricity.

[0024] Six sets of heat-conducting cavity forming dies 7 are inserted into one end of the extrusion core 6. These form the molds for the phase-change heat-conducting cavity 3, their outer shape matching the phase-change cavity structure of the sheath's inner wall. An injection port 701 is provided within the heat-conducting cavity forming dies 7, which communicate with the injection channel 603 and serve as the final outlet for the borax solution to be injected into the phase-change heat-conducting cavity 3. A dense network of thin-walled forming grooves 702 is defined on the outer side of one end of the heat-conducting cavity forming dies 7. These grooves squeeze the molten polyethylene during the extrusion process, simultaneously forming a thin heat-conducting wall 4 on the inner wall of the phase-change heat-conducting cavity 3. This eliminates the need for subsequent processing, improving production efficiency and ensuring the uniformity of the thin-walled structure.

[0025] A metered injection valve 8 is located at one end of the extrusion die 5. This valve precisely controls the amount of borax solution injected, ensuring synchronization with the sheath extrusion speed and preventing excess or insufficient solution from impacting cable performance. A honeycomb piston barrel 9 and a circular partition 10 are located within the metered injection valve 8. A solution inlet chamber 11 is located between the honeycomb piston barrel 9 and the circular partition 10. This chamber temporarily stores the borax solution introduced through a solution inlet 12, providing a buffer for the liquid aspiration process that drives the piston 901. A solution inlet 12 is located on one side of the solution inlet chamber 11, connected to a borax solution storage tank for continuous replenishment of the solution. A pressurized injection chamber 13 is located to the right of the honeycomb piston barrel 9. This chamber repressurizes the borax solution, ensuring that the solution penetrates and fills the phase change heat transfer chamber 3 before the polyethylene sheath is fully solidified. A dispersion inlet 14 is located to the right of the pressurized injection chamber 13. This dispersion inlet 14 communicates with the injection channels 603, evenly distributing the pressurized solution to each injection channel 603.

[0026] Six groups of drive pistons 901 are installed in the honeycomb piston cylinder 9. The six groups of drive pistons 901 move back and forth synchronously, achieving quantitative suction and push of the solution through volume changes. The multi-piston design can reduce the volume flow fluctuation of a single piston and improve metering accuracy. A piston rod 902 is fixedly connected to one end of the drive piston 901. The piston rod 902 passes through the circular partition 10 and is slidably connected to the circular partition 10 via a sealing sleeve. The sealing sleeve ensures the sealing of the piston rod 902 during movement, preventing solution leakage. A tilting disk 903 rotates inside the quantitative injection valve 8. The tilting disk 903 is the driving mechanism for the piston movement. Its tilting angle determines the piston stroke, thereby controlling the single injection volume. A sliding groove 904 is provided on the tilting disk 903, and a sliding ball head 905 is fixedly connected to one end of the piston rod 902. The sliding ball head 905 is slidably connected to the sliding groove 904. The cooperation between the sliding ball head 905 and the sliding groove 904 converts the rotational motion of the tilting disk 903 into the linear reciprocating motion of the piston rod 902, resulting in a compact structure and high transmission efficiency. A first one-way valve 906 is provided in the driving piston 901. The first one-way valve 906 controls the one-way flow of the solution into the driving piston 901. It opens when absorbing liquid and closes when discharging liquid. A second one-way valve 907 is provided at the opening on the right side of the honeycomb piston cylinder 9. The second one-way valve 907 controls the one-way flow of the solution out of the honeycomb piston cylinder 9. It opens when discharging liquid and closes when absorbing liquid. It cooperates with the first one-way valve 906 to achieve directional delivery of the solution.

[0027] A first gear 15 is fixedly connected to one side of the swash plate 903. This first gear 15 meshes with a second gear 16, which in turn meshes with a third gear 17. This three-stage gear transmission system reduces the speed of the drive motor 18 and increases its torque, ensuring smooth rotation of the swash plate 903. The gear ratio also precisely controls the piston's frequency to match the sheath extrusion speed. The metered injection valve 8 houses a drive motor 18, which powers the entire metered injection system. Frequency conversion allows for adjustable injection rates to suit varying production conditions. The output shaft of the drive motor 18 is fixedly connected to the third gear 17.

[0028] A cable core passage 19 runs through the metered injection valve 8. This passage serves as a guide for the conductor cable core 1. Its inner diameter matches that of the cable core passage 604, ensuring the cable core passes straight through the device and preventing deviation. The cable core passage 19 extends through the first gear 15, the tilting plate 903, the circular partition 10, and the honeycomb piston cylinder 9, and is in communication with the cable core passage 604.

[0029] Working principle: When the flame-retardant polyethylene sheath 2 is extruded, the quantitative injection valve 8 is also working. The driving motor 18 drives the inclined plate 903 to rotate through the gear. With the cooperation of the sliding groove 904 and the sliding ball head 905, the six groups of driving pistons 901 circulate back and forth in the honeycomb piston cylinder 9. By setting the inclination angle of the inclined plate 903 and matching it with the gear speed, the single liquid absorption volume and injection frequency of each group of pistons can be accurately controlled to ensure that the injection volume of the borax solution is completely synchronized with the sheath extrusion speed and the volume of the phase change heat conduction cavity 3, avoiding solution waste or insufficient filling. When the driving piston 901 moves to the left, the first one-way valve 906 opens and the second one-way valve 907 closes, so that the borax solution in the solution introduction chamber 11 will enter the honeycomb piston cylinder 9; as the driving piston 901 starts to move to the right, the first one-way valve 906 closes and the second one-way valve 907 opens, so that the borax solution in the honeycomb piston cylinder 9 will be squeezed into the pressurized injection chamber 13. The cross-sectional area of ​​the pressurized injection chamber 13 is smaller than that of the honeycomb piston cylinder 9. The solution pressure is further increased by the cross-sectional area difference to ensure that the solution can still quickly fill the phase change heat conduction cavity 3 when the viscosity of the polyethylene melt is high, and then enter the extrusion mold core 6 through the dispersed injection port 14, pass through the injection cavity 603 and the injection port 701 in turn, and then enter the newly formed phase change heat conduction cavity 3. At this time, the polyethylene sheath has not yet been completely solidified. After the solution is injected, it can fully contact the heat-conducting thin wall 4 on the inner wall of the sheath, providing conditions for subsequent crystallization and attachment.

[0030] The finished cable is introduced into a cooling tank, where the flame-retardant polyethylene sheath 2 rapidly cools. The borax solution also crystallizes due to the cooling, forming borax decahydrate, which adheres to the thermally conductive thin walls 4. The flaky structure of the thermally conductive thin walls 4 increases the crystallization area, preventing the solution from settling at the bottom of the cavity and ensuring uniform distribution of the phase change material. When exposed to high temperatures, the borax decahydrate gradually loses its water of crystallization, absorbing heat. The precipitated water also evaporates and absorbs heat, turning into water vapor. Each mole of borax decahydrate absorbs approximately 215 kJ of heat, effectively suppressing the sheath temperature from rising to its ignition point. The dehydrated borax flows along the phase change thermal cavity 3 to a lower temperature, where it condenses into liquid water and flows back to the higher temperature through the gaps between the thermally conductive thin walls 4 and between the borax crystals, forming a circulation system. The through-hole structure of the phase change thermal cavity 3 and the gaps between the thin walls provide a flow channel for water vapor, enabling continuous heat transfer through convection circulation. This creates a passive thermal management system of "heat absorption, heat dissipation, and recirculation," significantly improving the cable's flame retardancy and long-term operational reliability.

[0031] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A production equipment for flame retardant polyethylene sheathed cable, characterized in that: The invention comprises an extrusion die head (5), wherein an extrusion die core (6) is provided in the extrusion die head (5), wherein the extrusion die core (6) is inserted into the extrusion die head (5) from one end, wherein the extrusion die core (6) is composed of six groups of split die cores (601) spliced ​​together, wherein two copper hoops (602) are provided on the outside of the six groups of split die cores (601), and an injection cavity (603) for passing a borax solution is provided between each two groups of split die cores (601), and a cable core channel (604) for passing a conductor cable core (1) is provided in the center of the extrusion die core (6); six groups of heat-conducting cavity forming dies (7) are inserted into one end of the extrusion die core (6), wherein an injection port (701) is provided in the heat-conducting cavity forming dies (7), and wherein the injection port (701) is communicated with the injection cavity (603); wherein the heat-conducting cavity forming dies (7) are provided with a plurality of heat-conducting cavity forming dies ... ) is provided with dense thin-walled molding grooves (702) on the outside of one end, and a heat-conducting thin wall (4) is provided in the phase-change heat-conducting cavity (3); the cable comprises a conductor cable core (1), the conductor cable core (1) is wrapped with a flame-retardant polyethylene sheath (2) on the outside, a phase-change heat-conducting cavity (3) is provided in the flame-retardant polyethylene sheath (2), and a phase-change heat-conducting solution is injected into the phase-change heat-conducting cavity (3); the phase-change heat-conducting solution is a 20wt% borax aqueous solution, 1wt% sodium carboxymethyl cellulose is added as a thickener, and 5wt% glycerol is added as an anti-evaporation agent; a flame retardant is added to the flame-retardant polyethylene sheath (2), and 60 parts of magnesium hydroxide, 12.5 parts of ammonium polyphosphate, 5 parts of melamine, 7.5 parts of pentaerythritol and 5 parts of nano-montmorillonite are added to 100 parts of polyethylene matrix.

2. The production equipment for flame-retardant polyethylene sheathed cable according to claim 1, characterized in that: An extrusion cavity (501) is provided between the extrusion die core (6) and the extrusion die head (5), a polyethylene injection port (502) is provided on one side of the extrusion cavity (501), and an extrusion port (503) is provided at one end of the extrusion die head (5).

3. The production equipment for flame-retardant polyethylene sheathed cable according to claim 1, characterized in that: A quantitative injection valve (8) is provided at one end of the extrusion die head (5), a honeycomb piston cylinder (9) and a circular partition (10) are provided in the quantitative injection valve (8), a solution introduction cavity (11) is provided between the honeycomb piston cylinder (9) and the circular partition (10), a solution introduction port (12) is provided on one side of the solution introduction cavity (11), a pressurized injection cavity (13) is provided on the right side of the honeycomb piston cylinder (9), a dispersion injection port (14) is provided on the right side of the pressurized injection cavity (13), the dispersion injection port (14) is communicated with the injection cavity (603), and a cable core passing tube (19) passes through the quantitative injection valve (8).

4. The production equipment for flame-retardant polyethylene sheathed cable according to claim 3, characterized in that: Six groups of driving pistons (901) are provided in the honeycomb piston cylinder (9), one end of the driving piston (901) is fixedly connected to a piston rod (902), and the piston rod (902) passes through the circular partition (10). A tilting disk (903) rotates in the quantitative injection valve (8), and a sliding groove (904) is provided on the tilting disk (903). One end of the piston rod (902) is fixedly connected to a sliding ball head (905), and the sliding ball head (905) is slidably connected to the sliding groove (904).

5. The production equipment for flame-retardant polyethylene sheathed cable according to claim 4, characterized in that: The piston rod (902) is slidably connected to the circular partition (10) via a sealing sleeve.

6. The production equipment for flame-retardant polyethylene sheathed cables according to claim 5, characterized in that: A first one-way valve (906) is provided in the driving piston (901), and a second one-way valve (907) is provided at the right opening of the honeycomb piston cylinder (9).

7. The production equipment for flame-retardant polyethylene sheathed cable according to claim 4, characterized in that: A first gear (15) is fixedly connected to one side of the tilting plate (903), the first gear (15) is meshed with a second gear (16), the second gear (16) is meshed with a third gear (17), a driving motor (18) is provided in the quantitative injection valve (8), and an output shaft of the driving motor (18) is fixedly connected to the third gear (17).

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