Manufacturing equipment and method of power cable with synergistic water-blocking and heat-dissipating structure

Abstract

This invention discloses a manufacturing equipment and method for a power cable with a synergistic water-blocking and heat-dissipating structure, belonging to the field of power cable technology. The invention involves loading magnetic nanoparticles onto the surface of hexagonal boron nitride sheets to obtain sheet-like magnetic thermally conductive fillers. Inner and outer layer slurries are prepared using a shape-stabilizing binder, the sheet-like magnetic thermally conductive fillers, and superabsorbent resin. These slurries are simultaneously coated onto the outer surface of the traveling cable core using a concentric coating die, forming a synergistic water-blocking and heat-dissipating functional layer with a layered gradient distribution along the cable's radial direction. After curing, online orientation detection, and closed-loop control, a metal layer and outer sheath are applied to obtain the power cable. This invention enables the same functional layer to efficiently dissipate heat along the cable's radial direction in a dry state, and in a damp state, the superabsorbent resin blocks water and compresses the thermally conductive network to prevent heat dissipation degradation. Heat dissipation and water blocking are synergistic and do not weaken the cable's original water-blocking and electrical properties, while also ensuring consistent performance along the cable's length.

Description

Technical Field

[0001] This invention belongs to the field of power cable technology, and specifically relates to a manufacturing equipment and method for a power cable with a synergistic water-blocking and heat-dissipating structure. Background Technology

[0002] During the transmission of electrical energy, the conductors of power cables generate heat due to losses. This heat needs to be conducted radially from the cable core outwards and eventually dissipated into the surrounding environment. The cable's heat dissipation capacity directly determines the current it can carry under a given conductor temperature. For medium- and high-voltage power cables, a water-blocking layer is usually installed between the insulation shield and the metal layer of the cable core. This layer prevents moisture from seeping longitudinally and radially into the cable when it becomes damp or partially infiltrated, protecting the insulation from moisture damage. Power cables laid and operated on offshore platforms, seabeds, and other humid environments need to carry large currents and are exposed to environments prone to water ingress and moisture, placing high demands on both heat dissipation and water-blocking capabilities.

[0003] In existing technologies, the water-blocking layer placed between the insulation shield and the metal layer is mostly made of semi-conductive buffer water-blocking tape. These materials primarily function to block water, but their thermal conductivity is poor. Because this water-blocking layer is located on the path of heat conduction from the cable core, its poor thermal conductivity creates additional thermal resistance in the cable's radial direction, making it difficult for heat generated by the cable core to dissipate. This results in a higher conductor temperature, limiting the current the cable can carry under certain conductor temperatures. To improve the thermal conductivity of the water-blocking layer, some cables incorporate thermally conductive fillers. However, the thermal conductivity of sheet-like thermally conductive fillers is stronger in the planar direction than in the normal direction. When the filler is randomly distributed within the functional layer, the direction of high thermal conductivity of the filler may not align with the cable's radial direction, and adjacent fillers are difficult to continuously overlap along the cable's radial direction. Consequently, a continuous thermal conduction path extending radially cannot be formed within the functional layer, and heat conduction along the cable's radial direction remains obstructed.

[0004] Furthermore, it is often difficult to simultaneously achieve both water-blocking and heat dissipation functions within the same functional layer. Water-blocking materials absorb moisture and swell to block water seepage paths, but this swelling typically alters the original structural state of the functional layer. In existing technologies, the heat dissipation capacity of the water-blocking layer is often compromised after moisture absorption. The water-blocking and heat dissipation processes are mutually restrictive, making it difficult for the same functional layer to reliably achieve both simultaneously. To achieve both functions, additional layers or increased filler volume are often required. In continuous production of power cables, there is a lack of methods for quantitatively controlling the orientation of thermally conductive fillers within the functional layer. The directional arrangement of thermally conductive fillers within the functional layer is completed during the continuous movement of the cable core. Without quantitative criteria linking equipment, material, and process parameters, it is difficult to rationally set process conditions based on production line speed, making it difficult to consistently achieve the expected orientation level for the thermally conductive fillers. Simultaneously, existing technologies lack online detection and closed-loop control methods for the orientation of the functional layer. The orientation of the functional layer is not easily kept consistent along the cable length, resulting in fluctuations in the heat dissipation performance of the manufactured cable along its length.

[0005] In view of the above, it is necessary to provide a new power cable manufacturing equipment and method that enables the same functional layer of the power cable to have good radial heat dissipation capability in a dry state, and to have water-blocking capability and heat dissipation capability without degradation in a damp state. Furthermore, it enables the orientation degree of the thermally conductive filler in the functional layer to be quantitatively controlled, as well as to be detected online and controlled in a closed loop, so as to overcome the above-mentioned problems existing in the prior art. Summary of the Invention

[0006] To address the problems existing in the background art, the present invention provides a method for manufacturing a power cable with a synergistic water-blocking and heat-dissipating structure. The power cable includes a cable core, the cable core including a conductor and an insulation layer and an insulation shield disposed from the inside out outside the conductor; the manufacturing method includes the following steps:

[0007] S1. Surface treatment is performed on sheet-like hexagonal boron nitride, and magnetic nanoparticles are loaded on the surface of the sheet to obtain sheet-like magnetic thermally conductive filler with magnetic susceptibility in the plane of the sheet greater than that in the normal direction of the sheet.

[0008] S2. Using a shapeable adhesive as a matrix, an inner layer slurry and an outer layer slurry are prepared by using the sheet-like magnetic thermally conductive filler and superabsorbent resin. The mass ratio of the sheet-like magnetic thermally conductive filler to the superabsorbent resin in the inner layer slurry is greater than the mass ratio of the sheet-like magnetic thermally conductive filler to the superabsorbent resin in the outer layer slurry.

[0009] S3. The inner layer slurry and the outer layer slurry are simultaneously coated onto the outside of the continuously moving cable core through a concentric coating die to form an unshaped synergistic water-blocking and heat-dissipating functional layer with a layered gradient distribution along the radial direction of the cable. The side of the synergistic water-blocking and heat-dissipating functional layer closer to the cable core is a heat-conducting area, and the side farther away from the cable core is a water-blocking area.

[0010] S4. The cable core with the unshaped collaborative water-blocking and heat-dissipating functional layer is passed through the annular magnetic orientation device. The annular magnetic orientation device generates a transverse magnetic field that rotates around the cable axis, so that the sheet-like magnetic heat-conducting filler in the collaborative water-blocking and heat-dissipating functional layer is oriented and arranged, and the adjacent sheet-like magnetic heat-conducting fillers overlap or are adjacent to each other in the radial direction of the cable to form a heat-conducting network extending along the radial direction of the cable.

[0011] S5. Apply shaping conditions to the synergistic water-blocking and heat-dissipating functional layer to solidify or cool and solidify the shapeable adhesive, thereby locking the directional arrangement of the sheet-like magnetic thermally conductive filler.

[0012] S6. After online detection and shaping, determine the orientation degree of the sheet-like magnetic thermal conductive filler in the collaborative water-blocking and heat-dissipating functional layer. Based on the deviation between the orientation degree and the target range, adjust the transverse magnetic field generated by the annular magnetic orientation device or the traveling speed of the cable core.

[0013] S7. Apply a metal layer outside the synergistic water-blocking and heat-dissipating functional layer, and extrude an outer sheath outside the metal layer to obtain the power cable.

[0014] Further, step S1 includes:

[0015] S11. Placing the flake-shaped hexagonal boron nitride powder in an oxidizing treatment solution and heating it to introduce hydroxyl groups onto the surface of the hexagonal boron nitride flakes, then filtering, washing and drying to obtain hydroxylated hexagonal boron nitride flakes that exhibit a negative zeta potential in the liquid phase dispersion system.

[0016] S12. The magnetic nanoparticles are iron oxide nanoparticles. The iron oxide nanoparticles are surface modified to obtain magnetic nanoparticles with a positive ζ potential in the liquid dispersion system.

[0017] S13. The hydroxylated hexagonal boron nitride sheet and the magnetic nanoparticles with a positive zeta potential are mixed and stirred in the liquid-phase dispersion system, so that the magnetic nanoparticles with a positive zeta potential are adsorbed onto the surface of the hydroxylated hexagonal boron nitride sheet by electrostatic attraction. Then, a coupling agent is added for fixation treatment, so that the magnetic nanoparticles are stably bound to the surface of the hexagonal boron nitride sheet. After filtration, washing and drying, the sheet-like magnetic thermally conductive filler is obtained. In the obtained sheet-like magnetic thermally conductive filler, the magnetic nanoparticles are distributed on the surface of the hexagonal boron nitride sheet, so that the in-plane magnetic susceptibility of the sheet-like magnetic thermally conductive filler is greater than the normal magnetic susceptibility of the sheet.

[0018] Further, step S2 includes:

[0019] S21. A sculptable adhesive is provided, wherein the sculptable adhesive is a photocurable resin, a thermocurable resin, or a thermoplastic hot melt adhesive; when the sculptable adhesive is a photocurable resin or a thermocurable resin, a reactive diluent is added thereto and stirred evenly to obtain a matrix slurry; when the sculptable adhesive is a thermoplastic hot melt adhesive, it is heated and melted to obtain a matrix slurry; the viscosity of the matrix slurry is adjusted to a range suitable for concentric coating and allowing the sheet-like magnetic thermally conductive filler to rotate in a magnetic field;

[0020] S22. Take a portion of the matrix slurry, add the sheet-like magnetic thermally conductive filler and superabsorbent resin particles to it, stir to disperse it evenly, and obtain the inner layer slurry.

[0021] S23. Take another portion of the matrix slurry, add superabsorbent resin particles and the sheet-like magnetic thermally conductive filler to it, stir to disperse it evenly, and obtain the outer layer slurry.

[0022] Further, step S3 includes:

[0023] S31. The cable core is continuously and uniformly conveyed to the concentric coating die head;

[0024] S32. The inner layer slurry is coated onto the surface of the cable core through the inner channel of the concentric coating die, and the outer layer slurry is coated onto the outside of the inner layer slurry through the outer channel of the concentric coating die. The inner layer slurry and the outer layer slurry are overlapped and bonded together to form the unshaped collaborative water-blocking and heat dissipation functional layer.

[0025] S33. The inner layer slurry and the outer layer slurry are supplied through the inner channel and the outer channel respectively, so that the synergistic water-blocking and heat dissipation functional layer forms a layered gradient distribution from the inside to the outside along the radial direction of the cable, with the content of sheet-like magnetic thermally conductive filler decreasing and the content of superabsorbent resin increasing.

[0026] Further, step S4 includes:

[0027] S41. The cable core with the unshaped synergistic water-blocking and heat-dissipating functional layer is continuously fed into the annular magnetically controlled orientation device, which is sleeved on the outer periphery of the cable core.

[0028] S42. The transverse magnetic field generated by the annular magnetic orientation device rotates around the cable axis, causing the sheet-like magnetic thermal conductive filler in the synergistic water-blocking and heat-dissipating functional layer to rotate under the action of the transverse magnetic field; since the in-plane magnetic susceptibility of the sheet-like magnetic thermal conductive filler is greater than the normal magnetic susceptibility of the sheet, the sheet-like magnetic thermal conductive filler tends to be parallel to the cross-section of the cable, causing adjacent sheet-like magnetic thermal conductive fillers to overlap or be adjacent to each other in the radial direction of the cable, forming a thermal conductive network extending radially along the cable in the synergistic water-blocking and heat-dissipating functional layer;

[0029] S43. Measure the dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer and the anisotropy of the volumetric magnetic susceptibility of the sheet-like magnetic thermally conductive filler at the magnetically controlled orientation temperature. Set the magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer and the effective length of the annular magnetically controlled orientation device along the cable axis. Determine the upper limit of the cable core traveling speed according to the following formula, and control the cable core traveling speed not to exceed the upper limit, so that the sheet-like magnetic thermally conductive filler completes its directional arrangement within the dwell time of passing through the annular magnetically controlled orientation device.

[0030] ;

[0031] In the formula, This refers to the speed at which the cable core travels. The effective length of the annular magnetically controlled orientation device along the cable axis; represents the volume magnetic susceptibility anisotropy of the sheet-like magnetic thermally conductive filler, represents the difference between the in-plane volume magnetic susceptibility and the normal volume magnetic susceptibility of the sheet-like magnetic thermally conductive filler, and is a dimensionless quantity. The magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer; The dwell time safety factor is a dimensionless quantity greater than 1. Let be the free permeability, and let be the numerical value equal to . The constant; The dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer at the magnetron orientation temperature; The shape factor is a pre-calibrated dimensionless quantity, determined by the sheet diameter-to-thickness ratio of the sheet-like magnetic thermally conductive filler. Indicates magnetic flux density The square of; symbol This indicates that the quantity on its left is not greater than the quantity on its right.

[0032] Further, step S5 includes:

[0033] S51. Within a set distance after the cable core with the synergistic water-blocking and heat-dissipating functional layer leaves the annular magnetic orientation device, the synergistic water-blocking and heat-dissipating functional layer is shaped to prevent the directional arrangement of the sheet-like magnetic thermal conductive filler from loosening before shaping.

[0034] S52. Apply setting conditions according to the type of the settable adhesive: when the settable adhesive is a light-curing resin, irradiate the synergistic water-blocking and heat-dissipating functional layer with light to cure it; when the settable adhesive is a thermosetting resin, heat the synergistic water-blocking and heat-dissipating functional layer to cure it; when the settable adhesive is a thermoplastic hot-melt adhesive, use air cooling, cooling rollers, or a cooling device with a water-proof jacket to perform water-proof cooling on the synergistic water-blocking and heat-dissipating functional layer to solidify and set it; after the setting treatment, the directional arrangement state of the sheet-like magnetic thermally conductive filler is locked, resulting in a synergistic water-blocking and heat-dissipating functional layer with a stable orientation structure.

[0035] Further, step S6 includes:

[0036] S61. After the shaping process in step S5, a first detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the radial direction of the cable is obtained by the radial excitation detection coil, and a second detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the axial direction of the cable is obtained by the axial excitation detection coil.

[0037] S62. The degree of orientation is characterized by an orientation factor, which is a dimensionless quantity that characterizes the parallelism of the sheet plane of the sheet magnetic thermal conductive filler relative to the cross-section of the cable. The more parallel the sheet plane is to the cross-section of the cable, the larger the orientation factor. Based on the pre-calibrated correspondence between the difference between the first detection signal and the second detection signal and the orientation factor, the orientation factor of the sheet magnetic thermal conductive filler in the synergistic water-blocking and heat dissipation functional layer is determined by the difference between the first detection signal and the second detection signal.

[0038] S63. Compare the orientation factor determined in step S62 with the target range. If the orientation factor is lower than the lower limit of the target range, increase the magnetic induction intensity of the transverse magnetic field generated by the annular magnetic control orientation device or reduce the travel speed of the cable core. If the orientation factor is higher than the upper limit of the target range, reduce the magnetic induction intensity or increase the travel speed of the cable core, so that the orientation factor of the subsequent water-blocking and heat-dissipating functional layer on the cable core tends to the target range.

[0039] Further, step S7 includes:

[0040] S71. Apply a metal layer outside the collaborative water-blocking and heat dissipation functional layer. The metal layer is a corrugated metal sheath, a metal strip shielding layer, or a metal wire shielding layer.

[0041] S72. An outer sheath is extruded over the metal layer, cooled, and then wound up to obtain the power cable with a synergistic water-blocking and heat-dissipating structure.

[0042] The present invention provides a manufacturing equipment for power cables with a synergistic water-blocking and heat dissipation structure, comprising a wire feeding device, a concentric coating die, an annular magnetic orientation device, a curing and shaping unit, an online orientation detection unit, a metal layer application device, an outer sheath extrusion device, and a wire take-up device arranged sequentially along the cable core travel direction, and further comprising a traction device, a slurry supply unit, and a closed-loop controller.

[0043] The concentric coating die is used to coat the outer layer of the continuously moving cable core with inner and outer slurry to form a synergistic water-blocking and heat-dissipating functional layer. The concentric coating die has an inner channel and an outer channel that are coaxially sleeved and surround the cable core channel.

[0044] The slurry supply unit includes an inner mixing tank and an outer mixing tank, which are respectively connected to the inner and outer channels of the concentric coating die head via pipelines.

[0045] The annular magnetically controlled orientation device is sleeved on the outer periphery of the cable core. The curing and shaping unit is located downstream of the annular magnetically controlled orientation device. The orientation degree online detection unit is located downstream of the curing and shaping unit and is arranged around the cable core. The metal layer application device is located downstream of the orientation degree online detection unit. The outer sheath extrusion device is located downstream of the metal layer application device.

[0046] The signal output terminal of the orientation degree online detection unit is connected to the signal input terminal of the closed-loop controller, and the control output terminal of the closed-loop controller is connected to the annular magnetic orientation device and the traction device respectively.

[0047] 10. The manufacturing equipment according to claim 9, characterized in that the annular magnetically controlled orientation device includes a multiphase electromagnetic winding arranged circumferentially around the cable core channel and an AC excitation power supply for supplying power to the multiphase electromagnetic winding, wherein the controlled end of the AC excitation power supply is connected to the control output end of the closed-loop controller; when the multiphase electromagnetic winding is energized, a transverse magnetic field rotating around the cable axis is generated in the cable core channel, and the transverse magnetic field is used to drive the sheet-like magnetic thermally conductive filler in the synergistic water-blocking and heat dissipation functional layer to rotate and be oriented;

[0048] The outlet of the inner channel of the concentric coating head is located radially inside the outlet of the outer channel, so that the inner layer paste applied through the inner channel adheres to the surface of the cable core, and the outer layer paste applied through the outer channel overlaps with the outer side of the inner layer paste, so that the synergistic water-blocking and heat dissipation functional layer forms a layered gradient distribution along the radial direction of the cable.

[0049] The orientation online detection unit includes a radial excitation detection coil and an axial excitation detection coil arranged around the cable core, and a differential signal processing circuit connected to the radial excitation detection coil and the axial excitation detection coil. The radial excitation detection coil is used to acquire a first detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the cable radial direction, and the axial excitation detection coil is used to acquire a second detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the cable axis direction. The differential signal processing circuit determines the orientation degree of the sheet-like magnetic thermally conductive filler in the collaborative water-blocking and heat-dissipating functional layer based on the difference between the first detection signal and the second detection signal. The output terminal of the differential signal processing circuit is connected to the signal input terminal of the closed-loop controller.

[0050] The curing and shaping unit is a light curing unit, a heat curing device, or a water-isolated cooling device; the light curing unit is used to cure the light-curing resin, the heat curing device is used to cure the heat-curing resin, and the water-isolated cooling device is used to cool and solidify the thermoplastic hot melt adhesive under conditions isolated from water; the water-isolated cooling device is an air-cooling device, a cooling roller, or a cooling device with a water-isolated jacket.

[0051] It also includes a magnetic thermally conductive filler preparation unit, which comprises a hydroxylation reactor, a surface modification reactor, an electrostatic self-assembly mixing reactor, and a filtration and drying device connected in sequence. The outlet of the filtration and drying device is connected to the slurry supply unit. The hydroxylation reactor is used to perform hydroxylation treatment on sheet-like hexagonal boron nitride, the surface modification reactor is used to perform surface modification treatment on magnetic nanoparticles, and the electrostatic self-assembly mixing reactor is used to adsorb magnetic nanoparticles onto the sheet surface of hexagonal boron nitride sheets to obtain sheet-like magnetic thermally conductive filler.

[0052] The beneficial effects achieved by this invention are as follows:

[0053] This invention involves hydroxylating sheet-like hexagonal boron nitride to give its surface a negative zeta potential in a liquid dispersion system, and surface-modifying iron oxide nanoparticles to give them a positive zeta potential. Magnetic nanoparticles are then adsorbed onto the surface of the hexagonal boron nitride sheets via electrostatic self-assembly and fixed with a coupling agent to obtain a sheet-like magnetic thermally conductive filler. The magnetic nanoparticles are spread and distributed along the surface of the hexagonal boron nitride sheets. The in-plane magnetic susceptibility of the resulting sheet-like magnetic thermally conductive filler is greater than the normal magnetic susceptibility of the sheets, giving the inherently non-magnetically responsive hexagonal boron nitride a magnetic responsiveness that can be driven to rotate by a magnetic field, allowing the filler to rotate and orient in a desired direction in a magnetic field. The coupling agent fixation treatment ensures that the magnetic nanoparticles are stably bonded to the sheet surface and are not easily desorbed in subsequent processes, thus maintaining a stable rotational response of the sheet-like magnetic thermally conductive filler in a magnetic field. A relatively low loading of magnetic nanoparticles imparts sufficient magnetic responsiveness to the filler while avoiding the introduction of excessive conductive phase, thus not affecting the electrical performance of the synergistic water-blocking and heat-dissipating functional layer.

[0054] In the continuous cable core production process, before the slurry has solidified, a transverse magnetic field rotating around the cable axis is applied by a ring-shaped magnetically controlled orientation device. This causes the planar surface of the sheet-like magnetic thermally conductive filler to tend to be parallel to the cable cross-section, and adjacent fillers to overlap or be adjacent to each other along the cable radial direction. This forms a thermally conductive network extending radially within the synergistic water-blocking and heat-dissipating functional layer, and the orientation structure is then locked by a curing and shaping process. The thermal conductivity of the hexagonal boron nitride sheet planar direction is much higher than that in the normal direction. After the sheet planar surface is parallel to the cable cross-section, the cable radial direction falls precisely in the high thermal conductivity direction of the filler, allowing heat flow to be conducted along the sheet planar surface of a filler and then transferred to adjacent fillers through the overlap. After the sheet-like magnetic thermally conductive filler is oriented in a specific direction, the dry radial thermal conductivity of the synergistic water-blocking and heat-dissipating functional layer is significantly improved compared to when the filler is randomly distributed and compared to when there is no thermally conductive filler, thus reducing the radial thermal resistance of the cable. The decrease in radial thermal resistance of the functional layer reduces the conductor temperature under the same load current and improves the current carrying capacity of the cable under the same temperature limit. Thus, the present invention is reflected in the improvement of heat dissipation and current carrying capacity at the cable level.

[0055] This invention uses inner and outer layer slurries with different mass ratios of sheet-like magnetic thermally conductive filler and superabsorbent resin, which are simultaneously coated onto the outside of the cable core using a concentric coating die. This creates a layered gradient distribution along the cable radially from the inside out, with decreasing content of sheet-like magnetic thermally conductive filler and increasing content of superabsorbent resin. The side closer to the cable core is a heat-conducting zone, and the side farther from the cable core is a water-blocking zone. During operation, heat is conducted from the inside out. By placing the heat-conducting zone on the side where heat enters the functional layer, the heat-conducting network is densely distributed in the areas where heat dissipation is most needed. Since moisture typically seeps in from the outside of the cable, the water-blocking zone is placed on the side where moisture enters the functional layer, ensuring that the water-blocking and sealing capabilities are positioned where water blocking is most needed. Thus, both functions are achieved without increasing the total amount of sheet-like magnetic thermally conductive filler. When the synergistic water-blocking and heat-dissipating functional layer becomes damp, the superabsorbent resin absorbs water and swells, blocking the water seepage path and thus acting as a water barrier. Simultaneously, the pressure generated by the swelling compresses the overlapping interface between adjacent sheet-like magnetic thermally conductive fillers in the solidified and locked thermally conductive network. The contact thermal resistance of the overlapping interface decreases with increasing contact pressure. Experimental results show that the heat dissipation capacity of the functional layer containing the magnetron-controlled heat-dissipating network does not decrease after becoming damp but rather increases, consistently maintaining a level far higher than that of the comparative sample. Thus, the water-blocking and heat dissipation functions work synergistically within the same functional layer. The solidified thermally conductive network also provides spatial constraint on the swelling of the superabsorbent resin, limiting excessive swelling and preventing excessive swelling pressure from causing compression damage to the insulation shield. Therefore, this invention improves heat dissipation performance without weakening the cable's water-blocking and electrical properties.

[0056] Based on the balance between the magnetic torque experienced by the sheet-like magnetic thermally conductive filler in the transverse magnetic field and the viscous resistance torque experienced in the slurry, this invention derives a process window criterion that correlates parameters such as the effective length of the equipment, the dynamic viscosity of the slurry, the anisotropy of the volume magnetic susceptibility of the filler, and the transverse magnetic field strength with the cable core traveling speed. This correlation between equipment parameters, material parameters, and process parameters serves as the basis for setting the production line traveling speed, enabling quantitative control of the orientation process of the sheet-like magnetic thermally conductive filler. When the cable core traveling speed is within this process window, the sheet-like magnetic thermally conductive filler can achieve a near-saturated degree of orientation. When the traveling speed exceeds this window or no magnetic field is applied, the degree of orientation is significantly lower. The traveling speed that allows orientation to be completed can be determined at industrial production line speeds. The present invention further obtains the equivalent permeability related signals of the synergistic water-blocking and heat-dissipating functional layer along the radial direction and along the axial direction of the cable by radial excitation detection coil and axial excitation detection coil respectively after the curing and shaping process. The orientation degree of the sheet-like magnetic thermal conductive filler is determined by the difference between the two signals, and the transverse magnetic field strength or the traveling speed of the cable core is adjusted in a closed loop accordingly. The orientation degree is detected online and continuously corrected by closed-loop control. The orientation degree of the synergistic water-blocking and heat-dissipating functional layer is maintained within the target range in continuous production, and the heat dissipation performance of the manufactured power cable tends to be consistent along the length direction. Attached Figure Description

[0057] Figure 1 These are verification diagrams of the magnetically controlled orientation process window for Examples 1 to 4 and Comparative Example 3, where (a) is a scatter plot of the orientation factor as a function of travel speed, and (b) is a scatter plot of the magnetic induction intensity and the upper limit of the travel speed process window.

[0058] Figure 2 The diagrams show a comparison of the radial thermal conductivity of the functional layers in Examples 1 to 4 with those in Comparative Examples 2 and 3. (a) is a scatter plot of the orientation factor as the orientation time is established, and (b) is a scatter plot of the dry radial thermal conductivity as the orientation factor changes.

[0059] Figure 3 The graphs show a comparison of the heat dissipation performance of cables in Example 1 and Comparative Examples 1 and 2. In Example 2, (a) is a line graph showing the radial temperature distribution of the cable, and (b) is a line graph showing the change in conductor temperature with load current.

[0060] Figure 4 The diagram shows a comparison of the wet synergistic effect between Examples 1 to 4 and Comparative Examples 1 to 3, where (a) is a dumbbell plot of the radial thermal conductivity in dry and wet states, and (b) is a scatter plot of the rate of change of the wet thermal conductivity as a function of the orientation factor.

[0061] Figure 5 This is a schematic diagram of the manufacturing equipment for the power cable with a synergistic water-blocking and heat-dissipating structure according to the present invention.

[0062] Figure 6 This is a flowchart of the manufacturing method of the power cable with a synergistic water-blocking and heat-dissipating structure according to the present invention. Detailed Implementation

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] The power cable of this invention is a medium-voltage or high-voltage power cable. Its core includes a conductor and an insulation layer and an insulation shield disposed from the inside out on the outside of the conductor. For power cables with higher voltage levels, a conductor shield layer can also be disposed between the conductor and the insulation layer. The synergistic water-blocking and heat-dissipating functional layer refers to a composite functional layer disposed between the insulation shield and the metal layer of the cable core, possessing both water-blocking and radial heat dissipation functions within the same layer. The sheet-like magnetic thermally conductive filler refers to a filler obtained by loading magnetic nanoparticles onto the surface of sheet-like hexagonal boron nitride as a matrix. Hexagonal boron nitride is a ceramic material with a sheet-like structure; its thermal conductivity in the planar direction of the sheet is much greater than its thermal conductivity in the normal direction, and it also possesses electrical insulation properties. The superabsorbent resin refers to a polymer material that absorbs water and swells upon contact with water, forming a blockage in the seepage path of water. The shape-stabilizing adhesive refers to an adhesive that can be transformed from a fluid state to a fixed state through curing or cooling solidification, and plays a role in bonding and positioning the filler. The magneto-orientation temperature refers to the temperature at which the synergistic water-blocking and heat-dissipating functional layer is located when a transverse magnetic field is applied to cause the sheet-like magnetic thermally conductive filler to rotate and orient. The transverse magnetic field refers to the magnetic field in which the magnetic lines of force are located within the cross-section of the cable. The zeta potential refers to the potential characterization of the surface charge state of solid particles in a liquid-phase dispersion system. The orientation factor is a dimensionless quantity characterizing the degree of parallelism between the sheet-like magnetic thermally conductive filler's sheet plane and the cable cross-section.

[0065] This invention establishes a synergistic water-blocking and heat-dissipating functional layer between the cable core's insulation shield and the metal layer. Within this functional layer, sheet-like magnetic thermally conductive fillers and superabsorbent resin are simultaneously distributed. During the continuous cable core manufacturing process, a slurry containing both fillers is first coated onto the cable core. Then, before the slurry has solidified, a transverse magnetic field rotating around the cable axis is applied, causing the sheet-like magnetic thermally conductive fillers to oriented radially along the cable and overlap, forming a radially extending thermally conductive network within the functional layer. This oriented structure is then cured and locked. Thus, in a dry state, the synergistic water-blocking and heat-dissipating functional layer conducts heat generated by the cable core outwards through the radial thermally conductive network. In a damp state, the superabsorbent resin absorbs water, swells, and blocks water seepage paths. The pressure generated by the swelling presses the overlapping interfaces of the thermally conductive network, allowing the water-blocking and heat-dissipating functions to work together within the same functional layer. (Refer to...) Figure 6 The manufacturing method of the present invention includes steps S1 to S7, which will be described step by step below.

[0066] Step S1 involves preparing sheet-like magnetic thermally conductive fillers, including steps S11 to S13. In step S11, sheet-like hexagonal boron nitride powder is heated in an oxidizing solution to oxidize the surface of the hexagonal boron nitride sheets and introduce hydroxyl groups. After filtration, washing, and drying, hydroxylated hexagonal boron nitride sheets exhibiting a negative zeta potential in the liquid-phase dispersion system are obtained. The oxidizing solution is a treatment solution capable of oxidizing the surface of the hexagonal boron nitride sheets. The purpose of introducing hydroxyl groups is to ensure that the surface of the hexagonal boron nitride sheets exhibits a stable negative zeta potential in the subsequent liquid-phase dispersion system, providing a basis for electrostatic adsorption in subsequent steps. In step S12, the magnetic nanoparticles are iron oxide nanoparticles. The iron oxide nanoparticles undergo surface modification treatment to make them exhibit a positive zeta potential in the liquid-phase dispersion system, resulting in positively charged magnetic nanoparticles. Iron oxide is a magnetic material with magnetic responsiveness. In step S13, the hydroxylated hexagonal boron nitride sheets and magnetic nanoparticles with a positive zeta potential are mixed and stirred in the liquid-phase dispersion system. Since the two have negative and positive zeta potentials respectively in the dispersion system, the magnetic nanoparticles are adsorbed onto the surface of the hydroxylated hexagonal boron nitride sheets by electrostatic attraction. This process is electrostatic self-assembly, which refers to the spontaneous assembly of particles with opposite charges by electrostatic attraction. Subsequently, a coupling agent is added to the system for fixation treatment, so that the magnetic nanoparticles are stably bound to the surface of the hexagonal boron nitride sheets through the connection formed on the sheet surface by the coupling agent. After filtration, washing, and drying, the sheet-like magnetic thermally conductive filler is obtained. The purpose of adding the coupling agent for fixation treatment is to prevent the magnetic nanoparticles from detaching from the surface of the hexagonal boron nitride sheets during subsequent slurry preparation and coating processes. The bonding between the magnetic nanoparticles and the hexagonal boron nitride sheets is stable, and the rotational response of the sheet-like magnetic thermally conductive filler in the magnetic field is also stable. In the obtained sheet-like magnetic thermally conductive filler, magnetic nanoparticles are distributed on the surface of the hexagonal boron nitride sheets. The magnetic nanoparticles are spread along the surface of the sheets, making the in-plane magnetic susceptibility of the sheet-like magnetic thermally conductive filler greater than the normal magnetic susceptibility. That is, the sheet-like magnetic thermally conductive filler is magnetized to a greater extent along its planar direction than along its normal direction. This directional difference in magnetic susceptibility provides the conditions for the sheet-like magnetic thermally conductive filler to rotate and orient in the expected direction in step S4. In step S12, the loading of magnetic nanoparticles in the sheet-like magnetic thermally conductive filler is preferably kept at a low level to ensure that the sheet-like magnetic thermally conductive filler has sufficient magnetic responsiveness to be driven to rotate by a magnetic field, while avoiding the introduction of too much conductive phase that would affect the electrical performance of the synergistic water-blocking and heat-dissipating functional layer.

[0067] Step S2 involves preparing the coating slurry, including steps S21 to S23. In step S21, a stylistically adjustable binder is provided, which is one of three types of binders: photocurable resin, thermocurable resin, or thermoplastic hot melt binder. When the stylistically adjustable binder is a photocurable resin or a thermocurable resin, a reactive diluent is added and stirred evenly to obtain a matrix slurry. When the stylistically adjustable binder is a thermoplastic hot melt binder, it is heated and melted to obtain a matrix slurry. The viscosity of the matrix slurry is adjusted to a range suitable for concentric coating and allowing the sheet-like magnetic thermally conductive filler to rotate in a magnetic field. The viscosity of the photocurable resin or thermocurable resin is adjusted using a reactive diluent, and the flowability of the thermoplastic hot melt binder is adjusted by heating and melting. This ensures that both systems yield matrix slurries suitable for subsequent coating and orientation, and avoids introducing volatile or residual diluent components into the thermoplastic hot melt binder. The viscosity of the matrix slurry is preferably adjusted to a moderate range. Excessive viscosity will prolong the time required for the sheet-like magnetic thermally conductive filler to complete its rotational orientation in the magnetic field, while excessively low viscosity will hinder the retention of the slurry's morphology after coating. In step S22, a portion of the matrix slurry is taken, and the sheet-like magnetic thermally conductive filler and superabsorbent resin particles are added to it. The mixture is stirred to disperse it evenly, resulting in the inner layer slurry. In step S23, another portion of the matrix slurry is taken, and superabsorbent resin particles and the sheet-like magnetic thermally conductive filler are added to it. The mixture is stirred to disperse it evenly, resulting in the outer layer slurry. The mass ratio of the sheet-like magnetic thermally conductive filler to the superabsorbent resin in the inner layer slurry is greater than that in the outer layer slurry. That is, the relative proportion of thermally conductive filler is higher in the inner layer slurry, and the relative proportion of water-blocking resin is higher in the outer layer slurry. The concentric coating process in subsequent step S3 creates a layered difference in filler concentration along the radial direction of the cable in the synergistic water-blocking and heat-dissipating functional layer.

[0068] Step S3 is online concentric coating, including steps S31 to S33. In step S31, the cable core is continuously and uniformly fed to the concentric coating die. In step S32, the inner layer slurry is coated onto the surface of the cable core through the inner channel of the concentric coating die, and the outer layer slurry is coated onto the outside of the inner layer slurry through the outer channel of the concentric coating die. The inner and outer layer slurries overlap and adhere to each other to form an unshaped, synergistic water-blocking and heat-dissipating functional layer. The unshaped refers to the state where the shaped adhesive has not yet cured or cooled and solidified. In step S33, inner and outer layer slurries are supplied through the inner and outer channels of the concentric coating die, respectively. This creates a layered gradient distribution along the cable radially, with decreasing content of sheet-like magnetic thermally conductive filler and increasing content of superabsorbent resin. This gradient distribution results in a thermally conductive region with a higher proportion of sheet-like magnetic thermally conductive filler on the side of the synergistic water-blocking and heat-dissipating layer closer to the cable core, and a water-blocking region with a higher proportion of superabsorbent resin on the side farther from the cable core. Since heat is conducted from the inside to the outside during cable operation, placing the thermally conductive region closer to the cable core ensures a dense heat-conducting network on the side where heat enters the functional layer. Conversely, since moisture typically seeps in from the outside of the cable, placing the water-blocking region away from the cable core ensures that water-blocking capabilities are positioned on the side where moisture enters the functional layer. Thus, heat dissipation and water blocking capabilities are each positioned where they are most needed along the cable radially.

[0069] Step S4 is magnetically controlled orientation, including steps S41 to S43. In step S4, the sheet-like magnetic thermally conductive filler is radially oriented within the synergistic water-blocking and heat-dissipating functional layer of the cable. In step S41, the cable core with the unshaped synergistic water-blocking and heat-dissipating functional layer is continuously fed into the annular magnetically controlled orientation device, which is fitted around the outer periphery of the cable core. In step S42, the annular magnetically controlled orientation device generates a transverse magnetic field rotating around the cable axis, causing the sheet-like magnetic thermally conductive filler within the synergistic water-blocking and heat-dissipating functional layer to rotate under the influence of the transverse magnetic field. Since the in-plane magnetic susceptibility of the sheet-like magnetic thermally conductive filler is greater than the normal magnetic susceptibility, the sheet-like magnetic thermally conductive filler tends to align the sheet-like sheet with a greater degree of magnetization parallel to the direction of the magnetic field in the magnetic field; as the direction of the transverse magnetic field rotates around the cable axis over time, the sheet-like sheet-like magnetic thermally conductive filler subsequently tends to parallel to the cross-section of the cable. When the sheet-like magnetic thermally conductive filler has a plane parallel to the cable cross-section, the radial direction of the cable lies within the sheet plane, i.e., in the direction where the thermal conductivity of the hexagonal boron nitride sheet is higher. Adjacent sheet-like magnetic thermally conductive fillers along the cable radial direction overlap or are adjacent to each other. Heat can be conducted along the sheet plane of one filler and transferred to adjacent fillers through the overlap, forming a thermally conductive network extending radially from the cable core side to the metal layer side within the synergistic water-blocking and heat-dissipating functional layer. To quantitatively characterize the orientation degree of the sheet-like magnetic thermally conductive filler, an orientation factor known in the art is used, defined as shown in Formula 1.

[0070] (1);

[0071] In formula 1, is the orientation factor, which is a dimensionless quantity; The value of the square of the cosine of the angle between the normals of all sheet-like magnetic thermal conductive fillers within the synergistic water-blocking and heat-dissipating functional layer and the cable axis is a dimensionless quantity; 3 and 2 are constants in the definition of the orientation factor. When the sheet-like magnetic thermal conductive filler planes are all parallel to the cable cross-section, the sheet-like normals are all parallel to the cable axis, and the orientation factor is 1; when the sheet-like magnetic thermal conductive filler planes are randomly distributed in space, the orientation factor is 0; the larger the value of the orientation factor, the more parallel the sheet-like magnetic thermal conductive filler planes are to the cable cross-section, and the more complete the thermal conductive network extending radially along the cable.

[0072] In step S43, the dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer and the volumetric magnetic susceptibility anisotropy of the sheet-like magnetic thermally conductive filler are measured at the magnetically controlled orientation temperature. The magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer and the effective length of the annular magnetically controlled orientation device along the cable axis are set. The upper limit of the cable core travel speed is determined according to the process window, and the cable core travel speed is controlled not to exceed the upper limit value. The origin of this process window is explained below. In step S4, the sheet-like magnetic thermally conductive filler is subjected to a magnetic torque in the transverse magnetic field. Let the angle between the sheet plane of the sheet-like magnetic thermally conductive filler and the direction of the magnetic field be the deflection angle. Since the magnetic susceptibility in the sheet plane of the sheet-like magnetic thermally conductive filler is greater than the normal magnetic susceptibility of the sheet, the magnetic torque causes the deflection angle to tend to decrease. The magnitude of the magnetic torque is related to the volumetric magnetic susceptibility anisotropy of the sheet-like magnetic thermally conductive filler, the square of the magnetic induction intensity, and the sine of the deflection angle, and is inversely proportional to the vacuum permeability. Meanwhile, the sheet-like magnetic thermally conductive filler is subjected to viscous drag torque when rotating in the slurry. The magnitude of the viscous drag torque is related to the dynamic viscosity of the slurry and the rotational angular velocity of the sheet-like magnetic thermally conductive filler, and its proportionality coefficient is characterized by the shape factor determined by the aspect ratio of the sheet-like magnetic thermally conductive filler. Under the condition of neglecting inertia and overdamping, the magnetic torque and the viscous drag torque are in balance. After linearization for the case of small deflection angle, a first-order linear differential equation about the deflection angle is obtained, and the solution shows that the deflection angle decays exponentially with the orientation time. In the above balance relationship, the volume of the sheet-like magnetic thermally conductive filler is canceled out on both sides of the equation. Therefore, the speed at which the sheet-like magnetic thermally conductive filler completes rotational orientation is independent of its particle size and depends only on the dynamic viscosity of the slurry, the magnetic induction intensity, the anisotropy of the volume magnetic susceptibility, and the sheet shape. The orientation characteristic time corresponding to the exponential decay of the deflection angle is shown in Equation 2.

[0073] (2);

[0074] In formula 2, The orientation characteristic time of the sheet-like magnetic thermally conductive filler is expressed in seconds. The shape factor is a pre-calibrated dimensionless quantity, determined by the sheet diameter-to-thickness ratio of the sheet-like magnetic thermally conductive filler. Let be the free permeability, and let be the numerical value equal to . The constant, in units of H / m; The dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer at the magnetron orientation temperature, expressed in Pa·s; The volume magnetic susceptibility anisotropy of the sheet-like magnetic thermal conductive filler is the difference between the in-plane volume magnetic susceptibility and the normal volume magnetic susceptibility of the sheet, which is a dimensionless quantity. The magnetic flux density of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer is expressed in tons (T). Indicates magnetic flux density The square of.

[0075] As the deflection angle decays exponentially, the orientation factor of the sheet-like magnetic thermally conductive filler increases with orientation time according to a first-order saturation law. The relationship between the orientation factor and orientation time is shown in Equation 3.

[0076] (3);

[0077] In formula 3, For the time after orientation The orientation factor of the rear sheet-like magnetic thermally conductive filler is a dimensionless quantity. The saturation orientation factor that the sheet-like magnetic thermally conductive filler can achieve under the applied transverse magnetic field is a dimensionless quantity. is the base of the natural logarithm; The orientation time of the sheet-like magnetic thermally conductive filler in a transverse magnetic field is expressed in seconds. The orientation characteristic time is given in Formula 2, and the unit is seconds.

[0078] The cable core continuously passes through the annular magnetically controlled alignment device at a traveling speed. The alignment time of the sheet-like magnetic thermally conductive filler in the transverse magnetic field is the dwell time of the cable core within the annular magnetically controlled alignment device, and its value is the ratio of the effective length of the annular magnetically controlled alignment device to the traveling speed of the cable core. As shown in Formula 3, the alignment factor tends towards the saturation alignment factor as the alignment time increases. To ensure that the alignment factor of the sheet-like magnetic thermally conductive filler reaches a level close to its saturation alignment factor, this dwell time should not be less than the characteristic alignment time. The ratio of the effective length of the annular magnetically controlled orientation device to the cable core travel speed should be no less than [number missing]. and The product of and . Substituting Formula 2 into this condition and rearranging, we obtain the process window that the cable core traveling speed should satisfy, as shown in Formula 4.

[0079] (4);

[0080] In formula 4, The speed of the cable core is expressed in m / s. The effective length of the annular magnetically controlled orientation device along the cable axis is expressed in meters. The volume magnetic susceptibility anisotropy of the sheet-like magnetic thermally conductive filler has the same meaning as in Formula 2 and is a dimensionless quantity. The magnetic flux density of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer is expressed in tons (T). Indicates magnetic flux density The square of; The dwell time safety factor is a dimensionless quantity greater than 1. Let be the free permeability, and let be the numerical value equal to . The constant, in units of H / m; The dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer at the magnetron orientation temperature, expressed in Pa·s; The pre-defined shape factor has the same meaning as in Formula 2 and is a dimensionless quantity; symbol This indicates that the quantity on its left is not greater than the quantity on its right.

[0081] In the implementation of step S43, the dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer at the magnetron orientation temperature is... The anisotropy of the volumetric magnetic susceptibility of the sheet-like magnetic thermally conductive filler can be measured by a rotational viscometer. The magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer can be measured by a vibrating sample magnetometer. and the effective length of the ring-shaped magnetic orientation device Given by the device; shape factor The ratio of the sheet diameter to its thickness can be estimated using known hydrodynamic theory of sheet particles rotating in a viscous fluid. Alternatively, it can be calculated by measuring the time required for the sheet-like magnetic thermally conductive filler to reach a given orientation factor in a slurry with known dynamic viscosity and a magnetic field with known magnetic induction intensity, and then deduced by applying formulas 2 and 3, i.e., pre-calibration; safety factor. Take a value greater than 1. The value of is determined in advance based on the relationship between the orientation factor and the orientation time as defined in Formula 3, according to the requirements for the orientation factor. The larger the value, the closer the orientation factor of the sheet-like magnetic thermally conductive filler is to the saturation orientation factor, and the lower the allowable cable core travel speed. The preferred value is one that brings the orientation factor close to the saturation orientation factor. Based on this, the upper limit of the cable core travel speed is calculated using Formula 4, and the cable core travel speed is controlled below this upper limit, ensuring that the sheet-like magnetic thermally conductive filler completes its directional arrangement within the dwell time of the annular magnetically controlled orientation device. Formula 4 correlates equipment parameters (effective length), material parameters (dynamic viscosity and volume magnetic susceptibility anisotropy), and process parameters (magnetic induction intensity) with the travel speed into an inequality that can be directly used to set the production line travel speed. Those skilled in the art can determine the travel speed required to complete the orientation at industrial production line speeds based on Formula 4.

[0082] Step S5 is the curing and shaping process, which includes steps S51 and S52. In step S51, the water-blocking and heat-dissipating functional layer is shaped within a set distance after the cable core with the synergistic water-blocking and heat-dissipating functional layer leaves the annular magnetic alignment device. The set distance is the allowable travel distance of the cable core to prevent the oriented arrangement of the sheet-like magnetic thermally conductive filler from loosening before shaping. Before the synergistic water-blocking and heat-dissipating functional layer is shaped, the oriented sheet-like magnetic thermally conductive filler can still rotate in the slurry, causing the orientation factor to decrease. The shaping process of the synergistic water-blocking and heat-dissipating functional layer within the set distance after the cable core leaves the annular magnetic alignment device fixes the orientation structure before loosening occurs. In step S52, setting conditions are applied according to the type of settable adhesive. When the settable adhesive is a light-curing resin, the synergistic water-blocking and heat-dissipating functional layer is cured by light irradiation; when the settable adhesive is a thermosetting resin, the synergistic water-blocking and heat-dissipating functional layer is cured by heating; when the settable adhesive is a thermoplastic hot-melt adhesive, the synergistic water-blocking and heat-dissipating functional layer is cooled in a water-isolated manner using air cooling, cooling rollers, or a cooling device with a water-isolated jacket to solidify and set. The use of water-isolated cooling to prevent the synergistic water-blocking and heat-dissipating functional layer from contacting liquid water in the thermoplastic hot-melt adhesive system is because the synergistic water-blocking and heat-dissipating functional layer contains superabsorbent resin. If the superabsorbent resin comes into contact with liquid water before the metal layer is applied, it will prematurely absorb water and swell, disrupting the structure and layering gradient distribution of the synergistic water-blocking and heat-dissipating functional layer. After the setting treatment, the settable adhesive changes from a fluid state to a fixed state, and the directional arrangement of the sheet-like magnetic thermally conductive filler is locked, resulting in a synergistic water-blocking and heat-dissipating functional layer with a stable orientation structure that does not loosen due to subsequent processes.

[0083] Step S6 involves online orientation detection and closed-loop control, including steps S61 to S63. Step S6 ensures that the orientation of the synergistic water-blocking and heat-dissipating functional layer remains consistent throughout continuous production. In step S61, after the shaping process in step S5, a first detection signal related to the equivalent permeability of the synergistic water-blocking and heat-dissipating functional layer along the cable radial direction is acquired by a radial excitation detection coil, and a second detection signal related to the equivalent permeability of the synergistic water-blocking and heat-dissipating functional layer along the cable axis is acquired by an axial excitation detection coil. Because the sheet-like magnetic thermally conductive filler contains magnetic nanoparticles, the synergistic water-blocking and heat-dissipating functional layer exhibits an equivalent permeability detectable by inductive means. When the sheet-like magnetic thermally conductive filler tends to be arranged parallel to the cable cross-section, the equivalent permeability of the synergistic water-blocking and heat-dissipating functional layer along the cable radial direction differs from that along the cable axis. The larger the orientation factor, the greater this difference. In step S62, the orientation degree is characterized by an orientation factor, which is defined as shown in Formula 1. Based on the pre-calibrated correspondence between the difference between the first and second detection signals and the orientation factor, the orientation factor of the sheet-like magnetic thermally conductive filler in the synergistic water-blocking and heat-dissipating functional layer is determined by the difference between the first and second detection signals. The pre-calibrated correspondence is obtained by fitting the difference between the first and second detection signals of a set of calibration samples with known orientation factors. The orientation factor of the calibration samples can be determined by statistical observation of their cross-sections. In step S63, the orientation factor determined in step S62 is compared with the target range. When the orientation factor is lower than the lower limit of the target range, the magnetic induction intensity of the transverse magnetic field generated by the annular magnetically controlled orientation device is increased or the travel speed of the cable core is decreased. When the orientation factor is higher than the upper limit of the target range, the magnetic induction intensity of the transverse magnetic field is decreased or the travel speed of the cable core is increased, so that the orientation factor of the synergistic water-blocking and heat-dissipating functional layer on the subsequent cable core tends to the target range. As shown in Formula 4, the upper limit of the cable core travel speed increases with the increase of magnetic induction intensity, and different orientation results correspond to different travel speed settings. Therefore, increasing the magnetic induction intensity or decreasing the travel speed will increase the multiple of the orientation time of the sheet-like magnetic thermally conductive filler relative to the orientation characteristic time, and increase the orientation factor. Conversely, it will decrease the orientation factor. Step S63 adjusts the magnetic induction intensity or travel speed accordingly. Step S6 maintains the orientation factor of the synergistic water-blocking and heat-dissipating functional layer within the target range during continuous production, and the heat dissipation performance of the manufactured power cable tends to be consistent along the length direction.

[0084] Step S7 involves applying a metal layer and an outer sheath, including steps S71 and S72. In step S71, a metal layer is applied outside the synergistic water-blocking and heat-dissipating functional layer. This metal layer can be a corrugated metal sheath, a metal tape shielding layer, or a metal wire shielding layer. In step S72, an outer sheath is extruded over the metal layer, cooled, and then wound up to obtain the power cable with the synergistic water-blocking and heat-dissipating structure. The application of the metal layer and outer sheath is a standard procedure in power cable manufacturing. The metal layer provides radial water blocking and mechanical protection outside the synergistic water-blocking and heat-dissipating functional layer, while the outer sheath provides overall protection for the power cable.

[0085] The power cable produced through steps S1 to S7, in its dry state, utilizes a synergistic water-blocking and heat-dissipating functional layer. This layer, formed by the radial overlap of sheet-like magnetic thermally conductive fillers, conducts heat from the cable core from the inside out. The radial equivalent thermal conductivity of this layer is higher than that of the randomly distributed sheet-like magnetic thermally conductive fillers, thus reducing the radial thermal resistance of the power cable. When moisture seeps into the synergistic water-blocking and heat-dissipating functional layer from the outside of the cable, the superabsorbent resin absorbs and swells, blocking the water seepage path and thus impeding the moisture. Simultaneously, the pressure generated by the swelling of the superabsorbent resin acts on the solidified and locked thermally conductive network, compressing the overlap interface between adjacent sheet-like magnetic thermally conductive fillers along the cable's radial direction. This improves the contact condition at the overlap interface, and the interfacial contact thermal resistance between adjacent sheet-like magnetic thermally conductive fillers decreases with increasing contact pressure. The decreasing trend of interfacial contact thermal resistance with increasing contact pressure is consistent with the trend described by the widely accepted Cooper-Mikic-Yovanovich contact thermal conductivity correlation in the field of contact thermal resistance. This correlation is the accepted correlation used to describe the change of contact thermal conductivity with contact pressure. Therefore, the radial equivalent thermal conductivity of the synergistic water-blocking and heat-dissipating functional layer is maintained under humid conditions, and the heat dissipation capacity of the power cable under humid conditions does not decrease due to the water-blocking process. In addition, the cured thermally conductive network has a certain rigidity, which provides spatial constraint on the swelling of the superabsorbent resin, limiting excessive swelling of the superabsorbent resin and avoiding excessive swelling pressure that could cause extrusion damage to the insulation shield. Since the synergistic water-blocking and heat-dissipating functional layer is distributed in a layered gradient along the radial direction of the cable, the heat dissipation capacity and water-blocking capacity are respectively arranged in the more needed positions along the radial direction, allowing the two functions to perform independently without increasing the total amount of sheet-like magnetic thermally conductive filler.

[0086] The manufacturing equipment for implementing the above manufacturing method will be further described below. (Refer to...) Figure 5 The manufacturing equipment includes a wire feeding device, a concentric coating die, an annular magnetic orientation device, a curing and shaping unit, an online orientation detection unit, a metal layer application device, an outer sheath extrusion device, and a take-up device arranged sequentially along the cable core travel direction. It also includes a traction device, a slurry supply unit, and a closed-loop controller.

[0087] The cable-laying device is located at the beginning of the manufacturing equipment and is used to continuously lay out the cable core. The traction device is used to pull the cable core continuously along the manufacturing equipment, and the traveling speed of the cable core is determined by the traction device.

[0088] The concentric coating die is located downstream of the cable laying device. It has an inner channel and an outer channel coaxially fitted and surrounding the cable core channel. The outlet of the inner channel is radially inward of the outlet of the outer channel. The slurry supply unit includes an inner layer mixing tank and an outer layer mixing tank, which are connected to the inner and outer channels of the concentric coating die via pipelines. The inner layer slurry applied through the inner channel adheres to the cable core surface, while the outer layer slurry applied through the outer channel overlaps the outer side of the inner layer slurry. Since the outlet of the inner channel is radially inward of the outlet of the outer channel, the two slurries are concentrically overlapped on the outside of the cable core in the same process, forming a synergistic water-blocking and heat-dissipating functional layer. The layered gradient distribution of the synergistic water-blocking and heat-dissipating functional layer along the cable radial direction is directly formed by the difference in filler content between the slurries supplied by the inner and outer channels.

[0089] A ring-shaped magnetic alignment device is fitted around the outer circumference of the cable core, located downstream of the concentric coating die. The ring-shaped magnetic alignment device includes a multi-phase electromagnetic winding arranged circumferentially around the cable core channel and an AC excitation power supply for powering the multi-phase electromagnetic winding. The controlled end of the AC excitation power supply is connected to the control output of a closed-loop controller. When the multi-phase electromagnetic winding is energized, it generates a transverse magnetic field rotating around the cable axis within the cable core channel. This transverse magnetic field drives the sheet-like magnetic thermally conductive filler within the synergistic water-blocking and heat-dissipating functional layer to rotate and orient itself. The multi-phase electromagnetic winding is arranged circumferentially around the cable core channel and supplied with multi-phase current by the AC excitation power supply. The magnetic field vector synthesized by the multi-phase current within the cable core channel rotates around the cable axis over time, causing the sheet-like magnetic thermally conductive filler within the synergistic water-blocking and heat-dissipating functional layer to tend to be parallel to the cable cross-section.

[0090] The curing and setting unit is located downstream of the annular magnetron alignment device. This unit can be a UV curing unit, a heat curing unit, or a water-isolated cooling unit. The UV curing unit cures the synergistic water-blocking and heat-dissipating functional layer using UV-curable resin. The heat curing unit cures the synergistic water-blocking and heat-dissipating functional layer using thermosetting resin. The water-isolated cooling unit cools and solidifies the synergistic water-blocking and heat-dissipating functional layer using thermoplastic hot-melt adhesive under conditions isolated from water. The water-isolated cooling unit can be an air-cooled device, a cooling roller, or a cooling device with a water-isolated jacket. During the cooling process, the water-isolated cooling unit prevents the synergistic water-blocking and heat-dissipating functional layer from contacting liquid water, thus avoiding swelling of the superabsorbent resin in the synergistic water-blocking and heat-dissipating functional layer due to contact with liquid water before the metal layer is applied. The curing and setting unit, located downstream of the annular magnetron alignment device, fixes the directional arrangement of the sheet-like magnetic thermally conductive filler before relaxation occurs.

[0091] The orientation online detection unit is located downstream of the curing and shaping unit and surrounds the cable core. The orientation online detection unit includes a radial excitation detection coil and an axial excitation detection coil surrounding the cable core, and a differential signal processing circuit connected to the radial and axial excitation detection coils. The radial excitation detection coil acquires a first detection signal related to the equivalent permeability of the co-operated water-blocking and heat-dissipating functional layer along the cable radial direction. The axial excitation detection coil acquires a second detection signal related to the equivalent permeability of the co-operated water-blocking and heat-dissipating functional layer along the cable axial direction. The differential signal processing circuit determines the orientation degree of the sheet-like magnetic thermally conductive filler in the co-operated water-blocking and heat-dissipating functional layer based on the difference between the first and second detection signals. The output of the differential signal processing circuit is connected to the signal input of the closed-loop controller. Radial excitation detection coils and axial excitation detection coils are used to excite the synergistic water-blocking and heat-dissipating functional layer radially and axially, respectively, and pick up signals so that the equivalent permeability in the two directions can be characterized. The differential signal processing circuit performs differential processing on the two detection signals, and the difference between the two signals reflects the orientation degree of the sheet-like magnetic thermally conductive filler.

[0092] The signal input terminal of the closed-loop controller is connected to the signal output terminal of the online orientation detection unit, and the control output terminal of the closed-loop controller is connected to the annular magnetically controlled orientation device and the traction device, respectively. Based on the deviation between the orientation degree output by the online orientation detection unit and the target range, the closed-loop controller adjusts the AC excitation power supply of the annular magnetically controlled orientation device via its control output terminal to change the magnetic induction intensity of the transverse magnetic field, or adjusts the traction device to change the traveling speed of the cable core, so that the orientation degree of the subsequent water-blocking and heat-dissipating functional layer on the cable core tends to be within the target range, and the heat dissipation performance of the manufactured power cable tends to be consistent along its length.

[0093] The metal layer application device, located downstream of the orientation online detection unit, is used to apply a metal layer outside the synergistic water-blocking and heat-dissipating functional layer. The outer sheath extrusion device, located downstream of the metal layer application device, is used to extrude an outer sheath over the metal layer. The take-up device, located at the end of the manufacturing equipment, is used to wind up the resulting power cable.

[0094] The manufacturing equipment of this invention also includes a magnetic thermally conductive filler preparation unit. The magnetic thermally conductive filler preparation unit comprises a hydroxylation reactor, a surface modification reactor, an electrostatic self-assembly mixing reactor, and a filtration and drying device connected in sequence. The outlet of the filtration and drying device is connected to a slurry supply unit. The hydroxylation reactor is used to hydroxylate the sheet-like hexagonal boron nitride, the surface modification reactor is used to modify the surface of the magnetic nanoparticles, and the electrostatic self-assembly mixing reactor is used to adsorb the magnetic nanoparticles onto the surface of the hexagonal boron nitride sheets to obtain the sheet-like magnetic thermally conductive filler. The magnetic thermally conductive filler preparation unit can be connected online to the production line of the manufacturing equipment or set up offline independently of the production line.

[0095] Example 1. This example manufactures a 26 / 35kV medium-voltage cross-linked polyethylene insulated power cable, the cable core of which includes a nominal cross-section of 400mm². 2 The copper conductor and the conductor shielding layer, insulation layer and insulation shield disposed from the inside to the outside of the conductor are implemented according to steps S1 to S7.

[0096] Step S1 involves preparing sheet-like magnetic thermally conductive filler. In step S11, sheet-like hexagonal boron nitride powder with a diameter of approximately 15 μm and a thickness of approximately 0.4 μm is placed in an oxidizing treatment solution and heated. After filtration, washing, and drying, hydroxylated hexagonal boron nitride sheets exhibiting a negative zeta potential in an aqueous dispersion system are obtained. In step S12, the surface of iron(III) oxide nanoparticles is modified to obtain magnetic nanoparticles exhibiting a positive zeta potential in an aqueous dispersion system. In step S13, the hydroxylated hexagonal boron nitride sheets and magnetic nanoparticles are mixed and stirred in an aqueous dispersion system, allowing the magnetic nanoparticles to be electrostatically attracted and adsorbed onto the surface of the hexagonal boron nitride sheet layer. After adding a silane coupling agent for fixation treatment, the mixture is filtered, washed, and dried to obtain sheet-like magnetic thermally conductive filler with a magnetic nanoparticle loading of 3 wt%.

[0097] Step S2: Prepare the coating slurry. In step S21, using UV-curable resin as a shape-setting binder, a reactive diluent is added and stirred evenly to adjust the dynamic viscosity of the matrix slurry to 5 Pa·s. In step S22, sheet-like magnetic thermally conductive filler and superabsorbent resin particles are added to one portion of the matrix slurry at a mass ratio of 4:1, and stirred evenly to obtain the inner layer slurry. In step S23, superabsorbent resin particles and sheet-like magnetic thermally conductive filler are added to another portion of the matrix slurry at a mass ratio of 2.5:1, and stirred evenly to obtain the outer layer slurry.

[0098] Step S3: Online concentric coating. Step S31: The cable core is continuously and uniformly fed into the concentric coating die. Step S32: The inner and outer layer slurries are coated and overlapped through the inner and outer channels respectively, forming an unshaped, synergistic water-blocking and heat-dissipating functional layer with a thickness of 2.0 mm on the outside of the cable core. Step S33: The synergistic water-blocking and heat-dissipating functional layer is distributed in a layered gradient along the radial direction of the cable.

[0099] Step S4: Magnetic Orientation. Step S41 involves guiding the cable core into the annular magnetic orientation device. Step S42 involves the annular magnetic orientation device generating a transverse magnetic field rotating around the cable axis, with a magnetic induction intensity of 0.30T. This causes the planar surfaces of the sheet-like magnetic thermally conductive filler to tend to be parallel to the cable cross-section and allows adjacent sheet-like magnetic thermally conductive fillers to overlap. In Step S43, the effective length of the annular magnetic orientation device along the cable axis is 0.6m, and the safety factor is taken as 3. Formula 4 determines the upper limit of the cable core travel speed to be 25.8 m / min. -1 The cable core travel speed is taken as 20 m / min. -1 .

[0100] Step S5: Curing and Shaping. Step S51: Shaping treatment is performed within a set distance after the cable core leaves the annular magnetic alignment device. Step S52: The synergistic water-blocking and heat-dissipating functional layer is cured by ultraviolet light irradiation.

[0101] Step S6: Online orientation detection and closed-loop control. Step S61: The radial excitation detection coil and the axial excitation detection coil acquire the first detection signal and the second detection signal, respectively. Step S62: The orientation factor is determined by the difference between the first detection signal and the second detection signal through a calibration relationship. Step S63: The orientation factor is compared with the target range of 0.85 to 0.95, and the magnetic induction intensity or travel speed is adjusted accordingly. The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.89.

[0102] Step S7 involves applying a corrugated aluminum sheath as a metal layer outside the synergistic water-blocking and heat-dissipating functional layer, then extruding a polyethylene outer sheath, and finally winding the wire to obtain a power cable.

[0103] Example 2. The difference from Example 1 is that in step S21, thermosetting epoxy resin is used as a stylistable binder, and a reactive diluent is added to adjust the dynamic viscosity of the matrix slurry to 6 Pa·s; in step S13, the loading of magnetic nanoparticles is 5 wt%; in step S4, the magnetic induction intensity is 0.25 T, the effective length is 0.6 m, and the upper limit of the traveling speed determined by the formula is 14.9 m·min. -1 The travel speed is taken as 12 m / min. -1 In step S52, the synergistic water-blocking and heat-dissipating functional layer is cured by heating. The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.87.

[0104] Example 3. The difference from Example 1 is that in step S21, a thermoplastic hot-melt adhesive is used as the shape-stabilizing adhesive, and its dynamic viscosity is adjusted to 9 Pa·s after heating and melting; in step S13, the loading of magnetic nanoparticles is 2 wt%; in step S4, the magnetic induction intensity is 0.40 T, the effective length is 0.5 m, and the upper limit of the traveling speed determined by the formula is 21.2 m·min. -1 The travel speed is taken as 16 m / min. -1 In step S52, the synergistic water-blocking and heat-dissipating functional layer is cooled and solidified using a cooling device with a water-proof jacket; in step S7, the metal layer is a metal wire shielding layer. The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.90.

[0105] Example 4. The difference from Example 1 is that the loading of magnetic nanoparticles in step S13 is 4 wt%; the dynamic viscosity of the matrix slurry is adjusted to 4 Pa·s in step S21; the magnetic induction intensity is 0.50 T in step S4, the effective length is 0.7 m, and the upper limit of the travel speed determined by the formula is 104.5 m·min. -1 The travel speed is taken as 40 m / min. -1 The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.93.

[0106] Comparative Example 1. The difference from Example 1 is that the synergistic water-blocking and heat dissipation functional layer containing sheet-like magnetic thermally conductive filler is not provided. Instead, a conventional semi-conductive buffer water-blocking tape without thermally conductive filler is used outside the insulation shield of the cable core. The thickness is the same as 2.0 mm. The magnetic orientation in step S4 is not implemented.

[0107] Comparative Example 2. The difference from Example 1 is that the formulation of the synergistic water-blocking and heat-dissipating functional layer is the same as that of Example 1 and contains an equal amount of sheet-like magnetic thermally conductive filler. However, no transverse magnetic field is applied in step S4, and the sheet-like magnetic thermally conductive filler is randomly distributed in the functional layer. The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.05.

[0108] Comparative Example 3. The difference from Example 1 is that the formulation, magnetic induction intensity, and effective length of the synergistic water-blocking and heat-dissipating functional layer are the same as in Example 1, but the cable core travel speed in step S4 is 45 m·min. -1 This exceeds the upper limit of the process window of 25.8 m·min determined by Formula 4. -1 The orientation factor of the synergistic water-blocking and heat-dissipating functional layer of the manufactured power cable is 0.75.

[0109] Experimental Example 1: Verification of the magnetic orientation process window.

[0110] Samples were prepared using the methods of Examples 1 to 4, and Comparative Examples 2 and 3. The orientation factor was observed by scanning electron microscopy of the cross-section of the synergistic water-blocking and heat-dissipating functional layer and calculated according to Formula 1. Simultaneously, it was determined by the difference in equivalent permeability measured by the radial excitation detection coil and the axial excitation detection coil through calibration. The results obtained by the two methods were consistent. In the process window verification, the formulation and magnetic field conditions of Example 1 were used, with other conditions remaining unchanged, and travel speeds of 10, 15, 20, 25, 30, 40, and 55 m·min were selected. -1 Samples were prepared and orientation factors were measured separately. The process parameters and orientation factors for each example and comparative example are shown in Table 1.

[0111] Table 1: Process parameters and orientation factors for each embodiment and comparative example;

[0112]

[0113] As can be seen from Table 1, the travel speeds of Examples 1 to 4 are all no greater than the upper limit of travel speed calculated by Formula 4, and the resulting orientation factors are between 0.87 and 0.93; the travel speed of Comparative Example 3 is 45 m / min. -1 It is greater than the upper limit of its process window of 25.8 m·min -1 The orientation factor in Example 1 was only 0.75; in Comparative Example 2, no transverse magnetic field was applied, and the orientation factor was only 0.05. (Combined with...) Figure 1 In Example (b), the working points of Examples 1 to 4 all fall below their respective process window curves, while the working point of Comparative Example 3 falls above the curve. This indicates that when the travel speed in step S4 of this invention is within the process window determined by Formula 4, the sheet-like magnetic thermally conductive filler can achieve a near-saturated orientation factor; when it exceeds the window or no magnetic field is applied, the orientation factor is significantly lower. This demonstrates that the online magnetically controlled radial orientation process of this invention can be quantitatively controlled by Formula 4. Formula 4 correlates equipment parameters, material parameters, and process parameters into a criterion that can be directly used to set the production line travel speed. Its mechanism lies in the fact that the orientation characteristic time of the sheet-like magnetic thermally conductive filler is determined by the balance between the magnetic torque and the viscous resistance torque, and the residence time of the cable core in the annular magnetically controlled orientation device is not less than the orientation characteristic time. When the time-multiplication orientation factor is close to saturation, Equation 4 is the equivalent expression of this condition.

[0114] Table 2: Orientation factors of the formulation in Example 1 at different travel speeds;

[0115]

[0116] Note: The upper limit of the process window determined by Formula 4 is 25.8 m·min. -1 .

[0117] As shown in Table 2, under the formulation and magnetic field conditions of Example 1, the orientation factor decreases with increasing travel speed, and the travel speed does not exceed the upper limit of the process window of 25.8 m·min. -1 The orientation factor remained above 0.87 and approached saturation, and the travel speed increased to 55 m / min. -1 The orientation factor decreased to 0.69. (Combined) Figure 1 In Figure (a), the measured orientation factor matches the theoretical curve calculated by Formula 3. This indicates that the travel speed determines the dwell time of the cable core in the magnetic field, which in turn determines the orientation factor. A higher travel speed results in a shorter dwell time, and the orientation factor follows a first-order saturation law according to Formula 3. If the dwell time is insufficient, the orientation factor will not reach saturation.

[0118] Experimental Example 2: The formation law of orientation degree and its influence on the thermal conductivity of functional layer.

[0119] In the verification of orientation patterns, the method and formula of Example 1 were used, and the travel speed was fixed at 20 m / min. -1 Samples were taken at different positions along the axis of the annular magnetically controlled alignment device. The ratio of the sampling position to the travel speed was the alignment time, and the alignment factor corresponding to each alignment time was measured. The radial thermal conductivity of the functional layer was measured using the flash method. The alignment factors of the formulation in Example 1 at different alignment times are shown in Table 3.

[0120] Table 3: Orientation factor of the formulation in Example 1 at different orientation times;

[0121]

[0122] Note, The double orientation feature time is 1.40 s.

[0123] As shown in Table 3, at a fixed travel speed, the orientation factor increases with the extension of the orientation time. The orientation factor is 0.32 when the orientation time is 0.2 s, and rises to 0.89 when the orientation time increases to 1.8 s, then tends to saturate. Combined with... Figure 2 In (a), the measured orientation factor matches the theoretical curve calculated by Equation 3, and the orientation time reaches... After 1.40 s, the increase in the orientation factor slows down significantly. This indicates that the directional arrangement of the sheet-like magnetic thermally conductive filler is a process that gradually establishes itself over time and eventually approaches saturation. The sheet-like magnetic thermally conductive filler rotates under the drive of magnetic torque, but its rotation is hindered by viscous resistance torque. The balance between these two factors causes the orientation factor to approach the saturation orientation factor according to a first-order saturation law.

[0124] Table 4: Dry-state radial thermal conductivity of the functional layer in each embodiment and comparative example;

[0125]

[0126] As shown in Table 4, the dry radial thermal conductivity of the functional layer increases with the increase of the orientation factor, and is 0.26 W·m in Comparative Example 1 without thermally conductive filler. -1 ·K -1 In Comparative Example 2, the randomly distributed sheet-like magnetic thermally conductive filler yielded 1.05 W·m⁻¹. -1 ·K -1 When the orientation factor in Examples 1 to 4 is between 0.87 and 0.93, it is 2.23 to 2.31 W·m. -1 ·K -1 Combining Figure 2In (b), the measured data points of Examples 1 to 4, as well as Comparative Examples 2 and 3, all fall on the fitted curve of the orientation-average mixing relationship. This indicates that after the sheet-like magnetic thermally conductive filler is oriented, the radial thermal conductivity of the functional layer is increased by more than double compared to the randomly distributed type, and by about eight times compared to the type without thermally conductive filler. The thermal conductivity of the hexagonal boron nitride sheet in the planar direction is much higher than that in the normal direction. After the sheet plane is parallel to the cable cross-section, the cable radial direction falls into the high thermal conductivity direction. Adjacent sheet-like magnetic thermally conductive fillers overlap radially to form a continuous thermally conductive network, allowing heat flow to be continuously conducted radially.

[0127] Experimental Example 3: Cable Temperature Field and Current Carrying Capacity.

[0128] Samples were prepared using the methods of Examples 1 to 4 and Comparative Examples 1 to 3. The cable current carrying capacity and conductor temperature were determined by calculating the series thermal resistance of each radial layer of the cable, with an ambient temperature of 25°C and a maximum allowable conductor temperature of 90°C. The conductor temperature and maximum current carrying capacity for each example and comparative example are shown in Table 5.

[0129] Table 5: Conductor temperature and maximum current carrying capacity of each embodiment and comparative example;

[0130]

[0131] As shown in Table 5, under a load current of 1080A, the conductor temperature of Comparative Example 1 is 90.1℃, that of Comparative Example 2 is 86.8℃, and that of Examples 1 to 4 is 86.2℃. Regarding the maximum current carrying capacity, Comparative Example 1 is 1079.5A, Comparative Example 2 is 1107.7A, and Examples 1 to 4 are between 1112.8A and 1113.0A. (Combined with...) Figure 3 In Comparative Example 1 (a), the temperature drop across the functional layer is approximately 4.3°C, in Comparative Example 2 it is approximately 1.1°C, and in Example 1 it is approximately 0.5°C; combined with Figure 3 In (b), the conductor temperature increases with the increase of the load current. The current corresponding to a conductor temperature of 90°C is the maximum current carrying capacity. The maximum current carrying capacity of Example 1 is increased by about 3.1% compared to Comparative Example 1. Therefore, the increase in the radial thermal conductivity of the functional layer reduces the total radial thermal resistance of the cable, resulting in a lower conductor temperature and a higher current carrying capacity under the same temperature limit. The functional layer is located on the path of heat flow from the cable core outwards, and its radial thermal resistance is a component of the total radial thermal resistance of the cable. The radial thermal conductive network formed by the orientation process in step S4 reduces the thermal resistance of this layer, thereby improving the overall heat dissipation capacity of the cable.

[0132] Experimental Example 4: Wet Synergistic Effect.

[0133] Samples were prepared using the methods of Examples 1 to 4 and Comparative Examples 1 to 3. For each sample, the synergistic water-blocking and heat-dissipating functional layer was taken; one group was kept dry, while the other group was immersed in water and subjected to damp heat aging treatment before being removed. The radial thermal conductivity of both groups was measured using the flash method. The dry and wet radial thermal conductivity and their rate of change for each example and comparative example are shown in Table 6.

[0134] Table 6: Dry and wet radial thermal conductivity and rate of change for each embodiment and comparative example;

[0135]

[0136] As can be seen from Table 6, the wet radial thermal conductivity of the functional layers in Examples 1 to 4 increased by approximately 5.4% to 6.9% compared to the dry state, while the wet radial thermal conductivity remained between 2.35 and 2.47 W·m. -1 ·K -1 The thermal conductivity of the dry and wet states was relatively high; in Comparative Example 3, when the orientation was insufficient, the thermal conductivity of the wet state increased by only about 2.9%; although the thermal conductivity of the wet state of Comparative Examples 1 and 2 increased slightly after being exposed to moisture, their thermal conductivity of the dry and wet states remained between 0.26 and 1.07 W·m. -1 ·K -1 The low level. Combined with Figure 4 In example (a), the line connecting the dry and wet states in the embodiment is longer and located at a higher position, while the line connecting the comparative examples is shorter and comparative examples 1 and 2 are located at a lower position; combined with Figure 4 In (b), the rate of change of the wet radial thermal conductivity increases monotonically with the increase of the orientation factor, and the higher the orientation factor, the greater the increase. This indicates that the heat dissipation capacity of the functional layer containing the magnetron-controlled heat-conducting network does not decrease after becoming damp; on the contrary, it increases and remains at a level much higher than that of the comparative example. When the functional layer becomes damp, the superabsorbent resin absorbs water and swells. On the one hand, it blocks the water seepage path, thus acting as a water barrier; on the other hand, the pressure generated by the swelling compresses the overlapping interfaces between adjacent sheet-like magnetic thermally conductive fillers in the solidified and locked heat-conducting network. The contact thermal resistance of the overlapping interfaces decreases with the increase of the contact pressure. The higher the orientation factor, the more complete the thermally conductive network and the more overlapping interfaces can be compressed by the swelling pressure. Therefore, the rate of increase in wet thermal conductivity increases with the increase of the orientation factor. In contrast, the randomly distributed comparative example 2 and the comparative example 1 without a thermally conductive network, which lacks a connected thermally conductive network, can be compressed by the swelling pressure. After becoming damp, their radial thermal conductivity only changes slightly, and the absolute value remains very low. The positive correlation between the wet state increase and the orientation factor is a direct manifestation of the mechanism by which swelling pressure compresses the heat-conducting network. Factors unrelated to orientation, such as water filling the pores, cannot explain this phenomenon.

[0137] Experimental Example 5: Water Resistance and Electrical Performance.

[0138] The samples were prepared by the methods of Examples 1 to 4 and Comparative Examples 1 and 2. The water-blocking and electrical properties of each example and comparative example are shown in Table 7.

[0139] Table 7: Water-blocking and electrical properties of each example and comparative example;

[0140]

[0141] As can be seen from Table 7, the longitudinal water-blocking tests of each example and comparative example were all qualified, and no water leaked out after the tests. The insulation resistance of each sample was qualified and comparable between the examples and comparative examples. It can be seen that the functional layer prepared by introducing sheet-shaped magnetic thermal conductive fillers and subjecting them to magnetic control orientation does not weaken the water-blocking performance and electrical performance of the cable while improving the heat dissipation performance. It shows that the present invention can maintain the original basic performance of the cable while achieving the协同 of heat dissipation and water-blocking.

[0142] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method of manufacturing a power cable having a synergistic water-blocking heat dissipation structure, the power cable including a core including a conductor and an insulation layer and an insulation shield disposed outwardly of the conductor from the inside; characterized by, The manufacturing method includes the following steps: S1. Surface treatment is performed on sheet-like hexagonal boron nitride, and magnetic nanoparticles are loaded on the surface of the sheet to obtain sheet-like magnetic thermally conductive filler with magnetic susceptibility in the plane of the sheet greater than that in the normal direction of the sheet. S2. Using a shapeable adhesive as a matrix, an inner layer slurry and an outer layer slurry are prepared by using the sheet-like magnetic thermally conductive filler and superabsorbent resin. The mass ratio of the sheet-like magnetic thermally conductive filler to the superabsorbent resin in the inner layer slurry is greater than the mass ratio of the sheet-like magnetic thermally conductive filler to the superabsorbent resin in the outer layer slurry. S3. The inner layer slurry and the outer layer slurry are simultaneously coated onto the outside of the continuously moving cable core through a concentric coating die to form an unshaped synergistic water-blocking and heat-dissipating functional layer with a layered gradient distribution along the radial direction of the cable. The side of the synergistic water-blocking and heat-dissipating functional layer closer to the cable core is a heat-conducting area, and the side farther away from the cable core is a water-blocking area. S4. The cable core with the unshaped collaborative water-blocking and heat-dissipating functional layer is passed through the annular magnetic orientation device. The annular magnetic orientation device generates a transverse magnetic field that rotates around the cable axis, so that the sheet-like magnetic heat-conducting filler in the collaborative water-blocking and heat-dissipating functional layer is oriented and arranged, and the adjacent sheet-like magnetic heat-conducting fillers overlap or are adjacent to each other in the radial direction of the cable to form a heat-conducting network extending along the radial direction of the cable. S5. Apply shaping conditions to the synergistic water-blocking and heat-dissipating functional layer to solidify or cool and solidify the shapeable adhesive, thereby locking the directional arrangement of the sheet-like magnetic thermally conductive filler. S6. After online detection and shaping, determine the orientation degree of the sheet-like magnetic thermal conductive filler in the collaborative water-blocking and heat-dissipating functional layer. Based on the deviation between the orientation degree and the target range, adjust the transverse magnetic field generated by the annular magnetic orientation device or the traveling speed of the cable core. S7. Apply a metal layer outside the synergistic water-blocking and heat-dissipating functional layer, and extrude an outer sheath outside the metal layer to obtain the power cable.

2. The production method according to claim 1, characterized by, Step S1 includes: S11. Placing the flake-shaped hexagonal boron nitride powder in an oxidizing treatment solution and heating it to introduce hydroxyl groups onto the surface of the hexagonal boron nitride flakes, then filtering, washing and drying to obtain hydroxylated hexagonal boron nitride flakes that exhibit a negative zeta potential in the liquid phase dispersion system. S12. The magnetic nanoparticles are iron oxide nanoparticles. The iron oxide nanoparticles are surface modified to obtain magnetic nanoparticles with a positive ζ potential in the liquid dispersion system. S13. The hydroxylated hexagonal boron nitride sheet and the magnetic nanoparticles with a positive zeta potential are mixed and stirred in the liquid-phase dispersion system, so that the magnetic nanoparticles with a positive zeta potential are adsorbed onto the surface of the hydroxylated hexagonal boron nitride sheet by electrostatic attraction. Then, a coupling agent is added for fixation treatment, so that the magnetic nanoparticles are stably bound to the surface of the hexagonal boron nitride sheet. After filtration, washing and drying, the sheet-like magnetic thermally conductive filler is obtained. In the obtained sheet-like magnetic thermally conductive filler, the magnetic nanoparticles are distributed on the surface of the hexagonal boron nitride sheet, so that the in-plane magnetic susceptibility of the sheet-like magnetic thermally conductive filler is greater than the normal magnetic susceptibility of the sheet.

3. The production method according to claim 1, characterized by Step S2 includes: S21. A sculptable adhesive is provided, wherein the sculptable adhesive is a photocurable resin, a thermocurable resin, or a thermoplastic hot melt adhesive; when the sculptable adhesive is a photocurable resin or a thermocurable resin, a reactive diluent is added thereto and stirred evenly to obtain a matrix slurry; when the sculptable adhesive is a thermoplastic hot melt adhesive, it is heated and melted to obtain a matrix slurry; the viscosity of the matrix slurry is adjusted to a range suitable for concentric coating and allowing the sheet-like magnetic thermally conductive filler to rotate in a magnetic field; S22. Take a portion of the matrix slurry, add the sheet-like magnetic thermally conductive filler and superabsorbent resin particles to it, stir to disperse it evenly, and obtain the inner layer slurry. S23. Take another portion of the matrix slurry, add superabsorbent resin particles and the sheet-like magnetic thermally conductive filler to it, stir to disperse it evenly, and obtain the outer layer slurry.

4. The production method according to claim 1, characterized by Step S3 includes: S31. The cable core is continuously and uniformly conveyed to the concentric coating die head; S32. The inner layer slurry is coated onto the surface of the cable core through the inner channel of the concentric coating die, and the outer layer slurry is coated onto the outside of the inner layer slurry through the outer channel of the concentric coating die. The inner layer slurry and the outer layer slurry are overlapped and bonded together to form the unshaped collaborative water-blocking and heat dissipation functional layer. S33. The inner layer slurry and the outer layer slurry are supplied through the inner channel and the outer channel respectively, so that the synergistic water-blocking and heat dissipation functional layer forms a layered gradient distribution from the inside to the outside along the radial direction of the cable, with the content of sheet-like magnetic thermally conductive filler decreasing and the content of superabsorbent resin increasing.

5. The manufacturing method according to claim 1, characterized in that, Step S4 includes: S41. The cable core with the unshaped synergistic water-blocking and heat-dissipating functional layer is continuously fed into the annular magnetically controlled orientation device, which is sleeved on the outer periphery of the cable core. S42. The transverse magnetic field generated by the annular magnetic orientation device rotates around the cable axis, causing the sheet-like magnetic thermal conductive filler in the synergistic water-blocking and heat-dissipating functional layer to rotate under the action of the transverse magnetic field; since the in-plane magnetic susceptibility of the sheet-like magnetic thermal conductive filler is greater than the normal magnetic susceptibility of the sheet, the sheet-like magnetic thermal conductive filler tends to be parallel to the cross-section of the cable, causing adjacent sheet-like magnetic thermal conductive fillers to overlap or be adjacent to each other in the radial direction of the cable, forming a thermal conductive network extending radially along the cable in the synergistic water-blocking and heat-dissipating functional layer; S43. Measure the dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer and the anisotropy of the volumetric magnetic susceptibility of the sheet-like magnetic thermally conductive filler at the magnetically controlled orientation temperature. Set the magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer and the effective length of the annular magnetically controlled orientation device along the cable axis. Determine the upper limit of the cable core traveling speed according to the following formula, and control the cable core traveling speed not to exceed the upper limit, so that the sheet-like magnetic thermally conductive filler completes its directional arrangement within the dwell time of passing through the annular magnetically controlled orientation device. ； In the formula, This refers to the speed at which the cable core travels. The effective length of the annular magnetically controlled orientation device along the cable axis; represents the volume magnetic susceptibility anisotropy of the sheet-like magnetic thermally conductive filler, represents the difference between the in-plane volume magnetic susceptibility and the normal volume magnetic susceptibility of the sheet-like magnetic thermally conductive filler, and is a dimensionless quantity. The magnetic induction intensity of the transverse magnetic field at the synergistic water-blocking and heat-dissipating functional layer; The dwell time safety factor is a dimensionless quantity greater than 1. Let be the free permeability, and let be the numerical value equal to . The constant; The dynamic viscosity of the synergistic water-blocking and heat-dissipating functional layer at the magnetron orientation temperature; The shape factor is a pre-calibrated dimensionless quantity, determined by the sheet diameter-to-thickness ratio of the sheet-like magnetic thermally conductive filler. Indicates magnetic flux density The square of; symbol This indicates that the quantity on its left is not greater than the quantity on its right.

6. The manufacturing method according to claim 1, characterized in that, Step S5 includes: S51. Within a set distance after the cable core with the synergistic water-blocking and heat-dissipating functional layer leaves the annular magnetic orientation device, the synergistic water-blocking and heat-dissipating functional layer is shaped to prevent the directional arrangement of the sheet-like magnetic thermal conductive filler from loosening before shaping. S52. Apply setting conditions according to the type of the settable adhesive: when the settable adhesive is a light-curing resin, irradiate the synergistic water-blocking and heat-dissipating functional layer with light to cure it; when the settable adhesive is a thermosetting resin, heat the synergistic water-blocking and heat-dissipating functional layer to cure it; when the settable adhesive is a thermoplastic hot-melt adhesive, use air cooling, cooling rollers, or a cooling device with a water-proof jacket to perform water-proof cooling on the synergistic water-blocking and heat-dissipating functional layer to solidify and set it; after the setting treatment, the directional arrangement state of the sheet-like magnetic thermally conductive filler is locked, resulting in a synergistic water-blocking and heat-dissipating functional layer with a stable orientation structure.

7. The manufacturing method according to claim 1, characterized in that, Step S6 includes: S61. After the shaping process in step S5, a first detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the radial direction of the cable is obtained by the radial excitation detection coil, and a second detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the axial direction of the cable is obtained by the axial excitation detection coil. S62. The degree of orientation is characterized by an orientation factor, which is a dimensionless quantity that characterizes the parallelism of the sheet plane of the sheet magnetic thermal conductive filler relative to the cross-section of the cable. The more parallel the sheet plane is to the cross-section of the cable, the larger the orientation factor. Based on the pre-calibrated correspondence between the difference between the first detection signal and the second detection signal and the orientation factor, the orientation factor of the sheet magnetic thermal conductive filler in the synergistic water-blocking and heat dissipation functional layer is determined by the difference between the first detection signal and the second detection signal. S63. Compare the orientation factor determined in step S62 with the target range. If the orientation factor is lower than the lower limit of the target range, increase the magnetic induction intensity of the transverse magnetic field generated by the annular magnetic control orientation device or reduce the travel speed of the cable core. If the orientation factor is higher than the upper limit of the target range, reduce the magnetic induction intensity or increase the travel speed of the cable core, so that the orientation factor of the subsequent water-blocking and heat-dissipating functional layer on the cable core tends to the target range.

8. The manufacturing method according to claim 1, characterized in that, Step S7 includes: S71. Apply a metal layer outside the collaborative water-blocking and heat dissipation functional layer. The metal layer is a corrugated metal sheath, a metal strip shielding layer, or a metal wire shielding layer. S72. An outer sheath is extruded over the metal layer, cooled, and then wound up to obtain the power cable with a synergistic water-blocking and heat-dissipating structure.

9. A manufacturing equipment for a power cable with a synergistic water-blocking and heat-dissipating structure, characterized in that, It includes a wire feeding device, a concentric coating die, an annular magnetic orientation device, a curing and shaping unit, an online orientation detection unit, a metal layer application device, an outer sheath extrusion device, and a take-up device arranged sequentially along the cable core travel direction; it also includes a traction device, a slurry supply unit, and a closed-loop controller. The concentric coating die is used to coat the outer layer of the continuously moving cable core with inner and outer slurry to form a synergistic water-blocking and heat-dissipating functional layer. The concentric coating die has an inner channel and an outer channel that are coaxially sleeved and surround the cable core channel. The slurry supply unit includes an inner mixing tank and an outer mixing tank, which are respectively connected to the inner and outer channels of the concentric coating die head via pipelines. The annular magnetically controlled orientation device is sleeved on the outer periphery of the cable core. The curing and shaping unit is located downstream of the annular magnetically controlled orientation device. The orientation degree online detection unit is located downstream of the curing and shaping unit and is arranged around the cable core. The metal layer application device is located downstream of the orientation degree online detection unit. The outer sheath extrusion device is located downstream of the metal layer application device. The signal output terminal of the orientation degree online detection unit is connected to the signal input terminal of the closed-loop controller, and the control output terminal of the closed-loop controller is connected to the annular magnetic orientation device and the traction device respectively.

10. The manufacturing equipment according to claim 9, characterized in that, The annular magnetically controlled orientation device includes a multiphase electromagnetic winding arranged circumferentially around the cable core channel and an AC excitation power supply for supplying power to the multiphase electromagnetic winding. The controlled end of the AC excitation power supply is connected to the control output end of the closed-loop controller. When the multiphase electromagnetic winding is energized, it generates a transverse magnetic field rotating around the cable axis in the cable core channel. The transverse magnetic field is used to drive the sheet-like magnetic thermally conductive filler in the synergistic water-blocking and heat dissipation functional layer to rotate and be oriented. The outlet of the inner channel of the concentric coating head is located radially inside the outlet of the outer channel, so that the inner layer paste applied through the inner channel adheres to the surface of the cable core, and the outer layer paste applied through the outer channel overlaps with the outer side of the inner layer paste, so that the synergistic water-blocking and heat dissipation functional layer forms a layered gradient distribution along the radial direction of the cable. The orientation online detection unit includes a radial excitation detection coil and an axial excitation detection coil arranged around the cable core, and a differential signal processing circuit connected to the radial excitation detection coil and the axial excitation detection coil. The radial excitation detection coil is used to acquire a first detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the cable radial direction, and the axial excitation detection coil is used to acquire a second detection signal related to the equivalent permeability of the collaborative water-blocking and heat-dissipating functional layer along the cable axis direction. The differential signal processing circuit determines the orientation degree of the sheet-like magnetic thermally conductive filler in the collaborative water-blocking and heat-dissipating functional layer based on the difference between the first detection signal and the second detection signal. The output terminal of the differential signal processing circuit is connected to the signal input terminal of the closed-loop controller. The curing and shaping unit is a light curing unit, a heat curing device, or a water-cooled device; The light curing unit is used to cure the light-curing resin, the heat curing device is used to cure the heat-curing resin, and the water-isolated cooling device is used to cool and solidify the thermoplastic hot melt adhesive under conditions isolated from water; the water-isolated cooling device is an air-cooling device, a cooling roller, or a cooling device with a water-isolated jacket. It also includes a magnetic thermally conductive filler preparation unit, which comprises a hydroxylation reactor, a surface modification reactor, an electrostatic self-assembly mixing reactor, and a filtration and drying device connected in sequence. The outlet of the filtration and drying device is connected to the slurry supply unit. The hydroxylation reactor is used to perform hydroxylation treatment on sheet-like hexagonal boron nitride, the surface modification reactor is used to perform surface modification treatment on magnetic nanoparticles, and the electrostatic self-assembly mixing reactor is used to adsorb magnetic nanoparticles onto the sheet surface of hexagonal boron nitride sheets to obtain sheet-like magnetic thermally conductive filler.

Images