Crosslinked polyethylene insulating sheath water-blocking power cable and production equipment

Abstract

The invention discloses a crosslinked polyethylene insulating sheath water-blocking power cable and production equipment. Relates to the technical field of cable production. The cable at least comprises a standard insulation wire core, a composite gradient waterproof layer, a buffer liner layer, a metal shielding layer and a polyethylene sheath layer which are sequentially arranged from inside to outside. The composite gradient waterproof layer is composed of a gradient powder functional layer, a fiber reinforced fusion layer and an outer coating restraint layer which are fused into a whole through hot pressing, components of the powder layer are distributed in a radial gradient mode, and the inner layer is faster in water absorption response. The production equipment is a set of continuous operation system and comprises a wire core pretreatment and powder deposition subsystem, a pre-curing subsystem, a synchronous strip wrapping subsystem and a hot press molding subsystem, and the production equipment is formed by multi-channel precise deposition, waste heat recovery and pre-curing, mechanical linkage hot pressing and subsequent three-layer co-extrusion crosslinking. The high-efficiency and integrated continuous manufacturing of the water-blocking layer and the insulating body is realized, and the problems of easy migration and layering, single performance and low production efficiency of the water-blocking structure in the traditional process are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable production, in particular to a cross-linked polyethylene insulation sheath water-blocking power cable and a production equipment. BACKGROUND

[0002] Water-blocking power cable is the lifeline of power transmission system in harsh environments such as tunnels and subways. The core of its reliability is whether it can effectively prevent water from penetrating along the longitudinal direction of the cable after the outer sheath is damaged. At present, water resistance is mainly achieved by filling water-blocking powder / paste in the conductor twisting gap or wrapping water-blocking tape outside the cable core. However, the water-blocking structure formed by the above methods has inherent defects:

[0003] 1. The water-blocking powder is loosely filled, and the water-blocking tape is only mechanically wrapped. Both of them are physically stacked with the cable insulation body without firm combination. Under heat and mechanical stress, they are prone to migration and separation, not only losing their function, but also forming gaps that may become new water penetration channels and local discharge hazards.

[0004] 2. The existing production equipment can only perform simple filling or wrapping of homogeneous materials, and has no ability to precisely combine multiple functional materials according to a predetermined gradient, resulting in single product performance and inability to intelligently cope with complex water penetration conditions. Moreover, the application of the water-blocking layer (whether filling or wrapping) is usually completed in independent and discrete processes, which has poor coordination with the cable main insulation production line.

[0005] 3. The protection logic does not match the main risks. The most dangerous water penetration path is that after the sheath is damaged, water penetrates horizontally under the metal shielding layer and spreads longitudinally along the surface of the insulation core. The traditional wrapped water-blocking tape is easily penetrated or bypassed due to poor combination, and the protection reliability is insufficient. Therefore, building an active water-blocking layer on the surface of the insulation core, which is firmly combined and has designed performance, is the optimal path to intercept this risk.

[0006] In summary, the fundamental bottleneck of the existing technology is the lack of a special equipment and integrated advanced process that can directly and continuously complete the gradient powder precise deposition, adhesive uniform distribution, and synchronous wrapping of reinforcing fibers and restraint tape on the surface of the cable insulation core, and finally fuse them into a high-performance composite water-blocking layer. This results in the water-blocking structure always being in the primary stage of "loose filling" or "simple wrapping", which cannot meet the harsh requirements of high-reliability application scenarios. SUMMARY

[0007] To achieve the above purpose, the present application is implemented by the following technical scheme: a cross-linked polyethylene insulation sheath water-blocking power cable, the cable at least comprising, from inside to outside: a standard insulation core, a composite gradient water-blocking layer, a buffer pad layer, a metal shielding layer, and a polyethylene sheath layer.

[0008] The standard insulated core is composed of a conductor, a conductor shield layer, a cross-linked polyethylene insulation layer and an insulation shield layer from inside to outside;

[0009] The composite gradient water-blocking layer is coated outside the insulation shield layer of the standard insulated core, and the composite gradient water-blocking layer comprises a gradient powder functional layer, a fiber-reinforced fusion layer and an outer wrapping constraint layer which are fused into one body from inside to outside; wherein the gradient powder functional layer is composed of at least two powders with different water absorption characteristics, and the components thereof are distributed in a gradient along the radial direction, and the water absorption response speed of the inner layer powder is faster than that of the outer layer powder.

[0010] Preferably, the inner layer of the gradient powder functional layer contains superfine water-absorbing resin powder with a particle size D50 of 10-30 μm, and the outer layer contains a mixture of high-multiplying water-absorbing resin powder with a particle size D50 of 50-150 μm and short-cut reinforcing fibers.

[0011] Preferably, the buffer pad layer is a polyester tape layer.

[0012] A production device for a cross-linked polyethylene insulated sheath water-blocking power cable, the device is a set of continuous operation systems integrated in sequence along the production line, comprising:

[0013] A core pretreatment and powder deposition subsystem is used for preheating the standard insulated core and synchronously depositing at least two water-blocking powders with different particle sizes or components on the surface of the standard insulated core according to a set gradient ratio to form a loose powder layer, and spraying an atomized binder uniformly on the loose powder layer;

[0014] A pre-curing subsystem is connected to the core pretreatment and powder deposition subsystem, and makes the loose powder layer and the sprayed atomized binder pre-gelatinize by heating to form a stable embryo with cohesion;

[0015] A tape synchronous wrapping subsystem is connected to the pre-curing subsystem, and is used for synchronously wrapping the fiber-reinforced tape and the outer wrapping constraint tape on the stable embryo in sequence;

[0016] A hot-pressing molding subsystem is connected to the tape synchronous wrapping subsystem, and is used for hot-pressing the wrapped core, and the hot-pressing molding subsystem comprises a pair of heating press rollers which can apply pressure to each other and rotate around their own axes, and the two heating press rollers are symmetrically arranged on both sides of the cable, and their rotating movement is synchronized with the wrapping disc of the tape synchronous wrapping subsystem through a linkage mechanism;

[0017] The working temperature of the heating press rollers is controlled at 100-120 ℃.

[0018] Preferably, the core pretreatment and powder deposition subsystem comprises a preheating mechanism, a multi-channel precision co-deposition unit and an atomized spraying mechanism.

[0019] The preheating mechanism adopts hot air to preheat and dry the standard insulated wire core, and specifically comprises a preheating channel, a heating air supply unit and an air distribution plate, wherein the air distribution plate is in a cylindrical shape and is used to uniformly deliver the air blown by the heating air supply unit to the surface of the standard insulated wire core.

[0020] The multi-channel precision co-deposition unit has at least two independent powder supply channels, each of which comprises a powder bin, a screw feeder, a Venturi gas-solid mixer and an annular slit nozzle, and is used to realize the axial and radial gradient distribution of different powders on the surface of the standard insulated wire core.

[0021] The atomizing spraying mechanism comprises an annular atomizing nozzle, a metering pump and a liquid storage tank, and the metering pump and the liquid storage tank are arranged inside the containing box.

[0022] Preferably, the pre-curing subsystem comprises a pre-curing channel, a second air distribution plate and an air path system, wherein the air path system comprises an air guide pipe and an adjuster; one end of the air guide pipe is in communication with the air outlet side of the preheating channel, and the other end is connected to the air inlet of the pre-curing channel through the adjuster.

[0023] The adjuster is integrated with a temperature and humidity sensor, a fresh air supplement valve and a proportional adjusting valve, which are used to adjust the temperature and flow of the hot air entering the pre-curing channel according to the monitoring data.

[0024] Preferably, the strip synchronous wrapping subsystem comprises two independent wrapping machines, the surface of each wrapping machine is provided with an electrically rotating wrapping disc, and the wrapping disc of each wrapping machine is respectively provided with a fiber reinforced strip and an outer wrapping restraint strip for wrapping, and the two are sequentially and closely wrapped outside the stable embryo body in a spiral manner.

[0025] Preferably, the hot pressing forming subsystem comprises a rack, a rotating disc is rotatably connected to the surface of the rack, two heating pressure rollers are installed on the surface of the rotating disc through screw rod adjusting assemblies, a through hole is arranged at the center of the rack for the cable to pass through, and the heating pressure rollers realize power supply and temperature control signal transmission in the rotating state through the conductive slip ring arranged at the shaft center of the rotating disc.

[0026] Preferably, the linkage mechanism comprises a first gear ring sleeved on the rotating shaft of the wrapping disc and a second gear ring sleeved on the outer surface of the rotating disc, a pinion is engaged on one side of each of the first gear ring and the second gear ring, and the two pinions are connected through a rotating rod.

[0027] Preferably, the inlet of the hot pressing forming subsystem directly connects to the output end of the strip synchronous wrapping subsystem, and the distance between the two is less than 1 meter, so as to ensure that the wrapped wire core directly enters the hot pressing process within the active period of the adhesive.

[0028] Preferably, the device further comprises a central control system for synchronously coordinating the running speed, temperature, pressure and material flow of the core pretreatment and powder deposition subsystem, the pre-solidification subsystem, the tape synchronous wrapping subsystem and the hot-pressing subsystem, to realize closed-loop control of the whole process.

[0029] The application provides a cross-linked polyethylene insulated sheath water-blocking power cable and a production device.

[0030] 1. The application solves the problem of single performance of traditional water-blocking materials and inability to intelligently respond by providing a powder functional layer with radial gradient distribution. This gradient design enables the inner layer of superfine powder to respond quickly and preliminarily block when the water-blocking layer encounters water, and the outer layer of coarse particle powder then provides sustained swelling pressure, thereby realizing phased and intelligent water-blocking response to different water infiltration conditions, significantly improving the adaptability to dynamic water infiltration environments such as tunnels, and overcoming the defects of performance solidification of traditional homogeneous materials.

[0031] 2. The application combines the gradient powder, the fiber reinforced layer and the outer wrapping constraint layer by using a hot-pressing fusion process, and firmly combines them with the surface of the standard insulated core, to construct an integrated structure, thereby fundamentally solving the fatal problem of weak interface bonding between the traditional water-blocking layer such as wrapping tape and the surface of the cable insulated core and easy delamination failure. The process eliminates the physical interface between loose powder and wrapping tape, and forms a dense whole with mechanical interlocking and chemical bonding. This effectively prevents the migration and interlayer separation of water-blocking materials under vibration, bending or thermal stress, so that the water-blocking structure is no longer an additional part of the cable, but an integral part of the cable, greatly improving the long-term operation reliability of the cable.

[0032] 3. The core pretreatment and powder deposition subsystem of the device comprises a multi-channel precision co-deposition unit, which has at least two independent powder supply channels and high-precision quantitative feeding devices. This setting can accurately control the delivery ratio and spatial distribution of different characteristic powders online, thereby directly forming a powder preformed layer with radial gradient variation in composition and function on the surface of the cable insulated core, realizing the "programmability" and "designability" of water-blocking performance, and providing a core technical means for manufacturing high-performance customized water-blocking cables.

[0033] This invention systematically solves the industry pain points of low efficiency, high energy consumption, and poor process coordination inherent in traditional "two-step" discrete processes by constructing a sequentially integrated, uninterrupted, continuous composite water-blocking layer forming system and specifically setting up a thermal energy cascade utilization and wrapping hot-pressing mechanical linkage mechanism. First, the system achieves online integrated forming from loose powder to a dense composite water-blocking layer, integrating multiple discrete processes into a continuous production line, significantly improving production efficiency and consistency, and avoiding the pollution and damage that may result from step-by-step operations. Second, through a unique airflow design, the high-temperature waste heat from the core preheating channel is guided to the pre-curing channel, which only requires medium to low temperatures, achieving cascade utilization of thermal energy and significantly reducing overall energy consumption. Finally, the innovative mechanical linkage mechanism allows the rotation of the wrapping disc to directly drive the hot-pressing forming turntable, ensuring absolute rigid synchronization in time and space between the two key processes of strip wrapping and hot-pressing shaping. This allows the fiber tape and constraint tape to be immediately leveled and fused by heated rollers in optimal bonding condition after coating, completely eliminating adhesive failure or interlayer misalignment caused by process intervals, significantly improving interlayer bonding quality, structural density and product appearance consistency, and ensuring high process stability and repeatability. Attached Figure Description

[0034] Figure 1 This is an overall structural diagram of a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention;

[0035] Figure 2 This is a perspective view of the overall production equipment for a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention.

[0036] Figure 3 This is a top view of a production equipment for a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention.

[0037] Figure 4 This is a diagram showing the internal structure of the preheating channel in a production equipment for a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention.

[0038] Figure 5 This is an external view of the air distribution plate in the production equipment of a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention.

[0039] Figure 6 This is a partial structural diagram of a production equipment for a cross-linked polyethylene insulated and sheathed water-blocking power cable according to the present invention;

[0040] Figure 7 This is a diagram showing the internal structure of the wire core pretreatment and powder deposition subsystem in this invention.

[0041] Figure 8 This is an overall structural diagram of the strip synchronous winding subsystem and the hot pressing forming subsystem in this invention.

[0042] Wherein, 1, standard insulation wire core; 10, composite gradient water-blocking layer; 101, gradient powder functional layer; 102, fiber reinforced fusion layer; 103, outer wrapping restraint layer; 20, buffer pad layer; 30, metal shielding layer; 40, polyethylene sheath layer; 2, wire core pretreatment and powder deposition subsystem; 21, preheating mechanism; 211, preheating channel; 212, heating air supply unit; 213, air distribution plate; 22, multi-channel precision co-deposition unit; 221, powder bin; 222, screw feeder; 223, Venturi gas-solid mixer; 224, annular slit nozzle; 23, atomized spraying mechanism; 231, annular atomized nozzle; 232, containing box; 3, pre-solidification subsystem; 31, pre-solidification channel; 32, air duct; 33, regulator; 4, strip synchronous wrapping subsystem; 41, wrapping machine; 411, wrapping disc; 5, hot press molding subsystem; 51, rack; 52, rotary disc; 53, heating press roller; 54, linkage mechanism; 541, first gear ring; 542, second gear ring; 543, pinion; 544, rotating rod; 55, screw adjustment assembly. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0044] Reference Figures 1-8 :

[0045] Embodiment 1

[0046] The crosslinked polyethylene insulated sheath water-blocking power cable described in the embodiments of the present application is particularly suitable for medium voltage transmission lines with a voltage rating of 6kV to 35kV (such as 6 / 10kV, 8.7 / 15kV, 26 / 35kV grades), and provides high reliability power transmission for high humidity environments such as tunnels and subways.

[0047] As shown in Figure 1 , the cable of the present embodiment comprises, from the inside to the outside, a standard insulation wire core 1, a composite gradient water-blocking layer 10, a buffer pad layer 20, a metal shielding layer 30, and a polyethylene sheath layer 40.

[0048] The standard insulated core 1 is an electrical insulation unit fully meeting the requirements of IEC 60502 standard, which is composed of a conductor, a conductor shielding layer, a cross-linked polyethylene insulation layer and an insulation shielding layer from inside to outside, and is formed by three-layer co-extrusion and cross-linking process: the conductor is a type 2 annealed copper conductor meeting GB / T 3956 standard, which is tightly pressed and twisted to have excellent electrical conductivity and roundness.

[0049] The conductor shielding layer is made of semi-conductive cross-linked polyethylene material, which is co-extruded with the insulation layer to ensure close contact with the conductor and form a smooth interface to uniform the electric field.

[0050] The composite gradient water-blocking layer 10 is the core innovative structure of the application, which is coated outside the insulation shielding layer of the standard insulated core 1 and serves as a key longitudinal waterproof reinforcing layer of the cable. It is fused into a dense whole by one-time hot pressing process from inside to outside and specifically includes: a gradient powder functional layer 101 composed of at least two powders with different water absorption properties, the components of which are distributed in a gradient along the radial direction. In the preferred embodiment, three functional water-absorbing resin powders are used to realize the gradient distribution of continuous transition: the innermost component is mainly superfine sodium polyacrylate powder with a particle size D50 in the range of 10-15 μm. The powder has a large specific surface area and can gel quickly in 3-5 seconds after coming into contact with water, so it has extremely fast water absorption response speed. The middle transition layer component is a mixed zone of the above-mentioned superfine powder and polyacrylamide-acrylate copolymer powder with a particle size D50 of 30-60 μm. The latter has high water absorption rate and moderate response speed.

[0051] The outermost component is a mixture of high-ratio potassium polyacrylate powder with a particle size D50 of 80-120 μm and short-cut aramid fiber with a length of 2-3 mm and a mass ratio of about 8%. This layer mainly provides persistent sealing pressure, and the aramid fiber plays a role in reinforcing and toughening.

[0052] The three powders are sprayed out at a specific angle and airflow through independently controlled channels at the annular slit nozzle, mixed in space in the deposition cavity, and then deposited on the surface of the core, thereby forming a concentration gradient continuous transition layer from the inner layer of superfine powder to the outer layer of coarse particles.

[0053] The fiber-reinforced fusion layer 102 adopts an open-fiber polyester filament non-woven fabric with a grammage of 100 g / m². In the subsequent hot pressing process, the fiber part is partially melted and embedded in the pre-gelatinized gradient powder functional layer 101, forming a three-dimensional network reinforcing structure, which endows the composite layer with excellent tensile strength and crack resistance.

[0054] Outer constraint layer 103: Aluminum-plastic composite tape is used to provide a radial waterproof barrier, mechanical protection and certain electromagnetic shielding effect.

[0055] The composite gradient water-blocking layer 10 is made by on-line and continuous hot-pressing molding on the standard insulated core 1. The hot-pressing molding temperature is controlled at 100-120°C to ensure that the underlying insulation shielding layer is not damaged.

[0056] The buffer pad layer 20 is wrapped outside the composite gradient water-blocking layer 10. In this embodiment, the layer is a polyester tape formed by wrapping. Its role is to follow the cable standard design and provide mechanical buffering between the composite gradient water-blocking layer and the subsequent metal shielding layer to prevent the metal tape from damaging the underlying functional layer.

[0057] The metal shielding layer 30 is wrapped outside the buffer pad layer 20. It is made of tinned copper wire loosely wound or copper tape longitudinally wrapped to provide a reliable grounding path, short-circuit current capacity and complete electromagnetic shielding for the cable, fully meeting the mandatory safety standard requirements of medium-voltage cables.

[0058] The polyethylene sheath layer 40 is extruded on the metal shielding layer 30 as the outermost physical and environmental protection layer of the cable. High-density polyethylene or medium-density polyethylene sheath material is used, which has excellent wear resistance, corrosion resistance and environmental stress cracking resistance.

[0059] Example 2

[0060] The example provides a special production equipment for manufacturing the cable of example 1. As shown in Figures 2-8 The equipment is a continuous operation system integrated in sequence along the production line without human interruption, which can on-line composite powder, binder, fiber tape and outer constraint tape into a dense water-blocking layer on the standard insulated core.

[0061] The core pretreatment and powder deposition subsystem 2 is responsible for providing a clean and activated cable insulation core surface for powder adhesion and precisely constructing a gradient powder layer. Specifically, the preheating mechanism 21 is used to remove moisture from the surface of the core and increase its temperature to increase the powder adsorption force. The standard insulated core 1 first passes through the preheating channel 211. The heating air supply unit 212 generates clean hot air with a temperature of 70-90°C. The hot air is uniformly guided by the air distribution plate 213 to form a low-speed laminar hot air that wraps the core, ensuring that the core surface is uniformly preheated to 40-55°C. In this process, the hot air exchanges heat with the lower temperature core, and its own temperature will decrease, so the exhaust air will also be lower than 70-90°C. The multi-channel precision co-deposition unit 22 has three independent powder supply channels corresponding to the three powders in example 1. As shown in Figure 5As shown, each channel contains a powder bin 221, a screw feeder 222, a venturi gas-solid mixer 223 and an annular slit nozzle 224. The powder bin 221 is a closed container with a drying device. The screw feeder 222 is driven by a servo motor and outputs powder with an accuracy of gram per minute according to the instruction of the central control system. The venturi gas-solid mixer 223 disperses dry powder into a dilute phase gas-solid flow using compressed air. Each annular slit nozzle 224 corresponds to one kind of powder.

[0062] The central control system calculates the target rotation speed N of each servo motor of the screw feeder 222 according to the preset gradient formula, such as the target mass flow ratio of inner layer: middle layer: outer layer powder being 5:3:2 and the real-time linear speed V of the core. The control system performs independent closed-loop PID control on the servo motor of each screw feeder 222 through high-precision encoder feedback to ensure that the actual powder output flow Q is stable at the target value with an error of less than ±1.5%.

[0063] An electrical proportional valve and a flowmeter are arranged at the compressed air inlet of each venturi gas-solid mixer 223. The central control system dynamically adjusts the opening degree of the proportional valve of each channel according to the powder flow Q and the preset gas-solid ratio, such as 2:1, to maintain a stable carrier gas pressure of 0.3-0.6 MPa and flow, ensuring the uniformity and stability of powder delivery and preventing pipe blockage or gushing.

[0064] The three independent annular slit nozzles 224 are arranged in sequence and concentrically along the axis direction of the standard insulation core 1, i.e. the production line direction, and maintain a certain distance. The standard insulation core 1 passes through the center hole of each nozzle in sequence.

[0065] First step: inner layer powder basic deposition. The standard insulation core 1 first passes through the first nozzle corresponding to the innermost superfine powder. The nozzle has a relatively vertical spray angle, which directly and relatively concentrates the superfine powder on the clean surface of the standard insulation core 1 to form an initial layer.

[0066] Second step: middle layer powder superposition and preliminary mixing. The core with the initial layer enters the second nozzle corresponding to the middle layer powder. The nozzle has a slightly inclined spray angle, and its powder flow covers the existing powder layer on one hand, and its airflow disturbs the just-deposited and not completely stable powder in front, causing preliminary physical mixing of the two powders in the interface area.

[0067] Third step: outer layer powder wrapping and final mixing and shaping. The core wire finally passes through a third nozzle corresponding to the outer layer mixed powder. The spray angle of this nozzle is more inclined and the central angle is larger. The powder flow carries the fibers, and is sprayed out with a larger coverage area and kinetic energy. It can further interact with the front powder layer and form a wrapping on the outermost layer. At the same time, the strong airflow of the nozzle helps to "wipe" the surface of the front two layers of powder more evenly, promoting overall mixing and densification.

[0068] The atomizing spraying mechanism 23 sprays the binder immediately after the powder deposition. The annular atomizing nozzle 231 is evenly distributed in the circumferential direction, and the aqueous binder, such as a reactive polyurethane resin more suitable for low-temperature curing, in the liquid storage tank in the containment box 232 is quantitatively conveyed and atomized into a fine mist with a particle size of 10-50 μm by a metering pump, and is uniformly sprayed on the surface of the powder layer, with a spraying amount of about 15%-25% of the mass of the powder.

[0069] The pre-curing subsystem 3 is connected after spraying, and is used to cure the wet powder layer into a processable embryo. Specifically, the system includes a pre-curing channel 31. The heat source is innovative: the waste heat wind with a temperature reduced to 50-65℃ at the outlet of the preheating channel 211 is introduced through the air duct 32. The waste heat wind in this temperature range has a sufficient enthalpy to meet the needs of pre-curing, while absolutely avoiding the risk of overheating the underlying insulated core wire. The regulator 33 adjusts the proportion of hot air through the fresh air supplement valve and the proportional regulating valve according to the feedback of the internal temperature and humidity sensor, so as to accurately control the airflow entering the pre-curing channel 31 within the optimal process window of 45-60℃ and 40%-60% RH. This temperature range can effectively promote the pre-gelation of the binder, and is far below the temperature that may damage the insulated core wire. In this mild hot air environment, the binder undergoes pre-crosslinking to form a stable embryo with cohesion.

[0070] The strip synchronous wrapping subsystem 4 is used to build the reinforcing and restraining structure on the embryo. Specifically, the system includes two wrapping machines 41 arranged in front and back. The wrapping disc 411 of each wrapping machine 41 is driven to rotate by an independent servo motor. The first wrapping disc 411 releases the open-fiber polyester non-woven fabric, i.e. the fiber-reinforced fusion layer 102, and the second wrapping disc 411 releases the composite aluminum plastic tape, i.e. the outer wrapping restraining layer 103, both of which are tightly wrapped on the embryo in a spiral manner with an overlapping rate of about 30%-50%.

[0071] The hot press forming subsystem 5 is used for final shaping and is another core innovation point of the device. Specifically,

[0072] The system comprises a rotatable turntable 52 which is mounted on the frame 51 through bearings. A pair of heating press rollers 53 are symmetrically mounted on the turntable 52, and their radial positions can be accurately adjusted by the screw adjusting assembly 55 to adapt to different cable specifications. The heating press rollers 53 are integrated with electric heating rods and thermocouples inside, and the continuous power supply and temperature control signal transmission in the rotating state are realized through the conductive slip ring installed at the shaft center of the turntable 52, ensuring that the roller surface working temperature is stable at 100-120℃.

[0073] The linkage mechanism 54 is the key mechanical structure to realize synchronous heat pressing. As shown in Figure 8 In detail, the first gear ring 541 is fixed on the rotating shaft of the wrapping disc 411, and the second gear ring 542 is fixed on the outer edge of the turntable 52. The pitch diameter of the first gear ring 541 is designed to be smaller than that of the second gear ring 542. In order to enable the two gear rings to normally engage and transmit power, the diameter of the pinion gear 543 engaged with the first gear ring 541 is designed to be larger than that of the pinion gear 543 engaged with the second gear ring 542. The two pinion gears 543 with different diameters are coaxially fixed and coupled by a rigid rotating rod 544.

[0074] When the wrapping disc 411 is driven to rotate by the motor for wrapping, its rotating force is transmitted to the first pinion gear 543 engaged with the first gear ring 541. Since the two pinion gears 543 are rigidly coupled by the rotating rod 544, the power is synchronously transmitted to the second pinion gear 543, which in turn drives the second gear ring 542 and the entire turntable 52 to rotate.

[0075] Since the diameter of the first gear ring 541 is small, and the diameter of the pinion gear 543a engaged with it is large, the first stage transmission itself is a deceleration link. The power is then transmitted to the smaller diameter pinion gear 543 through the rotating rod 544, which drives the larger diameter second gear ring 542, and the second stage transmission is also a deceleration link. The superposition of two-stage deceleration finally makes the angular velocity of the turntable 52 stable and significantly lower than that of the wrapping disc 411, forming a fixed and optimized overall deceleration ratio.

[0076] Since the wrapping process requires a high rotational speed to ensure the tight wrapping of the tape, while the hot-pressing process requires a relatively slow and stable orbital speed so that the heating press roller 53 has a longer residence time to fully heat and press the cable surface. The design of the two-stage speed reduction makes the orbital linear speed of the hot-pressing roller automatically match the cable advancing speed, avoiding the insufficient heating or short pressure action time caused by excessive speed. At the same time, the speed reduction transmission means torque amplification. This ensures that even if the torque of the wrapping drive motor is limited, after two-stage gear reduction, the torque transmitted to the turntable 52 and the heating press roller 53 is large enough to overcome the resistance in the hot-pressing process, providing stable and uniform pressing force. Compared with the complex electronic synchronization system, this purely mechanical gear linkage structure is simple and reliable, and does not require additional sensors and high-speed control loops to achieve absolute rigidity and no slip between the phase and speed relationship of the wrapping and hot-pressing actions, ensuring the consistency and stability of the process. The wire core wrapped by the wrapping machine enters the pressing area formed by the two heating press rollers 53 within 1 meter. Under the drive of the turntable 52, the heating press roller 53 orbits the cable at this optimized lower speed, while applying a rolling pressure of 0.3-0.5 MPa and heat to the wire core, hot-pressing and fusing the multi-layer material into a dense composite gradient water-blocking layer 10 in one pass.

[0077] The central control system, as the brain of the equipment, its core function is to realize the global synchronization and process closed loop across subsystems. The system collects and processes real-time sensor signals from various places, including temperature sensors in the preheating channel 211, temperature and humidity sensors in the conditioner 33 of the pre-solidification channel 31, thermocouples in each heating press roller 53, and pressure sensors integrated on the screw adjustment assembly 55. Based on these data, the control system dynamically adjusts the power of the heating and air supply unit 212, the opening of each proportional valve, the speed of the adhesive metering pump, and the heater power of the heating press roller 53 through the PID algorithm, to ensure that the key process parameters such as temperature, pressure, flow, and humidity are stable within the set window. The operator can input or call different powder ratios, spraying amounts, temperature curves, etc. on the human-machine interface HMI. The central control system issues corresponding control parameters to each actuator. Key process data and production events are recorded and stored in real time, achieving traceability throughout the process.

[0078] The core working principle of the production equipment in this embodiment is to integrate loose powder, liquid adhesive, and solid tape into a high-performance integral water-blocking layer through a continuous integration, precise control, and mechanical linkage system. The working process and coordination mechanism are as follows:

[0079] The standard insulated wire core 1 first enters the wire core pretreatment and powder deposition subsystem 2. In the preheating mechanism 21, the wire core is uniformly preheated to 40-55℃ to activate the surface and remove moisture. Subsequently, the wire core enters the key multi-channel precision co-deposition unit 22. In this unit, the central control system independently and accurately controls the rotation speed of the three powder channels of the screw feeder 222, the air inlet pressure of the Venturi gas-solid mixer 223, and other collaborative controls according to the preset gradient formula, and the three powders with different characteristics form a specific spatial concentration field in the deposition cavity, thereby depositing a gradient powder layer with continuous composition change from inside to outside on the surface of the wire core. Then, the atomized spraying mechanism 23 uniformly sprays a certain amount of binder on the powder layer. Subsequently, the wire enters the pre-solidification subsystem 3, which utilizes the medium-temperature waste heat from the preheating mechanism 21 with a temperature drop of 50-65℃ to make the binder pre-gel at an environment of 45-60℃, thereby converting the loose powder layer into a stable embryo with certain strength and plasticity. This process realizes one-step conversion of the material from powder to a processable embryo and realizes heat energy recycling.

[0080] The formed stable embryo then enters the strip synchronous wrapping subsystem 4. Two wrapping machines 41 are started in sequence under the speed synchronization of the central control system, and the wrapping discs 411 of the two wrapping machines 41 respectively tightly wrap the opened fiber reinforced strip and the outer wrapping restraint strip on the embryo in a spiral manner, completing the preliminary wrapping of the reinforcing structure and the outer protective layer. Subsequently, the wrapped wire core immediately enters the hot-press forming subsystem 5 for final structure fusion and shaping.

[0081] When the wrapping disc 411 rotates, the power is transmitted through the first tooth ring 541 fixed on the rotating shaft thereof. The power is transmitted to another pinion 543 engaged with the second tooth ring 542 on the outer edge of the rotating disc 52 through the pinion 543 and the rigid rotating rod 544, thereby driving the entire rotating disc 52 to rotate. Since the diameter of the first tooth ring 541 is smaller than that of the second tooth ring 542, this transmission mechanism constitutes a fixed reduction ratio. This makes the angular velocity of the rotating disc 52 and the pair of heating and pressing rollers 53 mounted thereon in revolution lower than the angular velocity of the wrapping disc 411, but accurately matches the forward speed of the cable and the required residence time of the hot-press process. Under the driving of the rotating disc 52, the two heating and pressing rollers 53 revolve around the cable at an optimized speed, and the internal heating temperature of the heating and pressing rollers 53 is kept constant at 100-120℃. At the same time, the heating and pressing rollers 53 are driven to rotate by the servo drive, and the linear speed is synchronized with the forward speed of the cable. The wire core passes between the two pressing rollers while being subjected to radial pressure of 0.3-0.5 MPa and circumferential rolling heating. This process is completed under the absolute synchronization of mechanical linkage, realizing seamless connection of the wrapping and hot-pressing processes in time and space. The heat and pressure make the binder inside completely solidify, and the gradient powder layer, the fiber reinforced layer, and the outer restraint layer are fused and interwoven into a dense, solid, and interface-free whole, i.e., the final composite gradient water-blocking layer 10.

[0082] Throughout the whole process, the central control system implements global monitoring and closed-loop control. It synchronizes the movement speed of all subsystems, and collects process parameters such as temperature, pressure, flow, humidity in real time, dynamically adjusts the heating power, fan speed, valve opening and feeding speed, ensures the continuity, stability of the production process and the high consistency of the process parameters, so as to guarantee the uniformity and reliability of product performance.

[0083] After the composite gradient water-blocking layer 10 is formed online, the core does not need to be wound and taken off, and directly enters the subsequent metal shielding layer and sheath extrusion production line. The subsequent processes include: first, wrapping a buffer lining layer 20 such as a polyester tape and a metal shielding layer 30 such as a copper tape outside the composite gradient water-blocking layer 10, and then the cable enters the sheath extrusion system. A separate extruder uses high-density polyethylene or medium-density polyethylene sheath material to extrude and wrap outside the metal shielding layer 30 to form the outermost polyethylene sheath layer 40. The sheath layer provides mechanical protection, corrosion resistance and moisture barrier.

[0084] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A cross-linked polyethylene insulated and sheathed water-blocking power cable, characterized in that: The cable comprises, from the inside out, at least the following components arranged sequentially: a standard insulated core (1), a composite gradient water-blocking layer (10), a buffer pad layer (20), a metal shielding layer (30), and a polyethylene sheath layer (40). The standard insulated wire core (1) consists of a conductor, a conductor shielding layer, a cross-linked polyethylene insulation layer, and an insulation shielding layer from the inside out; The composite gradient water-blocking layer (10) covers the insulation shielding layer of the standard insulated wire core (1). The composite gradient water-blocking layer (10) includes a gradient powder functional layer (101), a fiber-reinforced fusion layer (102), and an outer covering constraint layer (103) that are fused together from the inside to the outside by hot pressing. The gradient powder functional layer (101) is composed of at least two powders with different water absorption properties, and its components are distributed in a gradient along the radial direction. The water absorption response speed of the inner powder is faster than that of the outer powder.

2. The cable according to claim 1, characterized in that: The inner layer of the gradient powder functional layer (101) contains ultrafine water-absorbing resin powder with a particle size D50 of 10-30 μm, and the outer layer contains powder with a particle size D50 of 10-30 μm. It is a mixture of high-ratio water-absorbing resin powder with a diameter of 50-150μm and short-cut reinforcing fibers; The cushioning pad layer (20) is a polyester tape layer.

3. A production apparatus for manufacturing the cross-linked polyethylene insulated and sheathed water-blocking power cable as described in claim 1, characterized in that: The equipment is a continuous operation system sequentially integrated along the production line, including: The core pretreatment and powder deposition subsystem (2) is used to preheat the standard insulated core (1) and simultaneously deposit at least two different particle sizes or compositions of water-blocking powder on the surface of the standard insulated core (1) in a set gradient ratio to form a loose powder layer, and uniformly spray atomized adhesive onto the loose powder layer. The pre-curing subsystem (3) is connected to the core pretreatment and powder deposition subsystem (2). By heating, the loose powder layer and the sprayed atomized binder are pre-gelled to form a stable preform with cohesive force. The tape synchronous wrapping subsystem (4) is connected after the pre-cured subsystem (3) and is used to synchronously wrap the fiber-reinforced tape and the outer covering constraint tape on the stable preform. The hot pressing forming subsystem (5) is connected after the strip synchronous wrapping subsystem (4) and is used to hot press and shape the wrapped wire core. The hot pressing forming subsystem (5) includes a pair of heating pressure rollers (53) that can apply pressure in opposite directions and rotate around their own axis. The two heating pressure rollers (53) are symmetrically arranged on both sides of the cable. Their rotational motion is synchronized with the wrapping disc (411) of the strip synchronous wrapping subsystem (4) through the linkage mechanism (54). The working temperature of the heated pressure roller (53) is controlled at 100-120℃.

4. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 3, characterized in that: The core pretreatment and powder deposition subsystem (2) includes a preheating mechanism (21), a multi-channel precision co-deposition unit (22), and an atomizing spraying mechanism (23). The preheating mechanism (21) uses hot air to preheat and dry the standard insulated wire core (1), specifically including a preheating channel (211), a heating air supply unit (212) and an air distribution plate (213). The air distribution plate (213) is cylindrical and is used to uniformly transport the air blown out by the heating air supply unit (212) to the surface of the standard insulated wire core (1). The multi-channel precision co-deposition unit (22) has at least two independent powder supply channels, each of which includes a powder bin (221), a spiral metering feeder (222), a Venturi gas-solid mixer (223), and an annular slit nozzle (224) to achieve axial and radial gradient distribution of different powders on the surface of a standard insulated wire core (1). The atomizing spraying mechanism (23) includes an annular atomizing nozzle (231), a metering pump, and a liquid storage tank, wherein the metering pump and the liquid storage tank are disposed inside the housing (232).

5. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 4, characterized in that: The pre-curing subsystem (3) includes a pre-curing channel (31), a second air distribution plate and an air path system. The air path system includes an air duct (32) and a regulator (33). One end of the air duct (32) is connected to the air outlet side of the preheating channel (211), and the other end is connected to the air inlet of the pre-curing channel (31) through the regulator (33). The regulator (33) integrates a temperature and humidity sensor, a fresh air intake valve and a proportional control valve, which are used to adjust the temperature and flow rate of the hot air entering the pre-curing channel (31) according to the monitoring data.

6. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 5, characterized in that: The tape synchronous wrapping subsystem (4) includes two independent wrapping machines (41). The surface of the wrapping machine is provided with an electrically rotating wrapping disc (411). The wrapping discs (411) of the two wrapping machines (41) are respectively provided with fiber reinforcement tape and outer covering constraint tape for wrapping. The two are wrapped tightly around the stable preform body in a spiral manner.

7. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 3, characterized in that: The hot pressing subsystem (5) includes a frame (51), on which a turntable (52) is rotatably connected. Two heating rollers (53) are mounted on the surface of the turntable (52) via a screw adjustment assembly (55). A through hole is provided at the center of the frame (51) for cables to pass through. The heating rollers (53) transmit power and temperature control signals during rotation through a conductive slip ring located at the axis of the turntable (52).

8. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 7, characterized in that: The linkage mechanism (54) includes a first toothed ring (541) sleeved on the rotating shaft of the wrapper (411) and a second toothed ring (542) sleeved on the outer surface of the turntable (52). A pinion (543) is meshed on one side of both the first toothed ring (541) and the second toothed ring (542), and the two pinions (543) are connected by a rotating rod (544).

9. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 6, characterized in that: The inlet of the hot pressing molding subsystem (5) is directly connected to the output end of the strip synchronous wrapping subsystem (4), and the distance between the two is less than 1 meter, so as to ensure that the wrapped wire core can directly enter the hot pressing process within the active period of the adhesive.

10. The production equipment for cross-linked polyethylene insulated and sheathed water-blocking power cables according to claim 3, characterized in that: The equipment also includes a central control system, which is used to synchronously coordinate the operating speed, temperature, pressure and material flow of the core pretreatment and powder deposition subsystem (2), pre-curing subsystem (3), strip synchronous wrapping subsystem (4) and hot pressing subsystem (5) to achieve closed-loop control of the entire process.

Images