Photovoltaic cable with continuous crosslinked insulation and its extrusion profiling device

Abstract

The application belongs to the technical field of photovoltaic cable manufacturing, and discloses a photovoltaic cable with a continuously cross-linked insulation layer and an extrusion and shaping device thereof, which comprises a head shell, a liquid supply and shunt assembly and a rigid shaping die seat arranged in the head shell in sequence along the extrusion direction, and a rigid guide die core is coaxially fixed in the head shell. The radial floating sleeve is arranged, and is radially supported and limited by an elastic damping matrix, and the dynamic sealing of the front and rear end faces is realized by using end face sliding sealing elements, so that the extrusion flow channel still remains closed and continuous under the condition of allowing slight radial floating. When the asymmetric radial thrust appears due to the difference in circumferential resistance, the radial floating sleeve can generate corresponding radial bias and change the local flow channel gap, thereby passively balancing the circumferential pressure distribution, reducing the occurrence probability of the eccentricity of the insulation layer and the fluctuation of the circumferential wall thickness, and improving the forming consistency during continuous extrusion.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic cable manufacturing technology, specifically a photovoltaic cable with a continuous cross-linked insulation layer and its extrusion and shaping processing device. Background Technology

[0002] Photovoltaic cables are used for power transmission between photovoltaic modules and combiner boxes or inverters, and operate under conditions of outdoor temperature and humidity, ultraviolet radiation, thermal cycling, and bending traction for extended periods. Currently, the insulation layer of most photovoltaic cables uses polyolefin materials, and the cross-linking reaction and cooling are completed in the cross-linking section after continuous extrusion coating of the conductor to achieve heat resistance and insulation properties.

[0003] During continuous extrusion coating, molten polyolefin materials are sensitive to temperature and shear. The pressure and flow rate are easily uneven in the circumferential direction of the die head flow channel due to factors such as flow splitting deviation, viscosity fluctuation or assembly eccentricity. Existing common fixed die core and die sleeve structures are difficult to adaptively compensate for the above imbalances during operation, which can easily lead to insulation layer eccentricity, circumferential wall thickness fluctuation or outer diameter instability, affecting the consistency of finished products and the stability of continuous production.

[0004] Meanwhile, in the cross-linking section, the cross-linking reaction and cooling process require stable gas and thermal process boundaries; if the inlet gas environment is unstable or the gas inside the insulation layer is not sufficiently discharged, defects may be formed in the insulation layer body or interface, affecting the compactness and long-term reliability. Summary of the Invention

[0005] The purpose of this invention is to provide a photovoltaic cable with a continuous cross-linked insulation layer and an extrusion forming apparatus thereof to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a photovoltaic cable with a continuous cross-linked insulation layer and its extrusion shaping processing device, including a die head housing and a liquid supply and diversion component and a rigid shaping mold seat arranged sequentially inside the die head housing along the extrusion direction;

[0007] A rigid guide mold core is coaxially fixed inside the die head housing. A radial floating sleeve is sleeved between the liquid supply and diversion assembly and the rigid shaping mold base. The inner wall of the radial floating sleeve and the outer wall of the rigid guide mold core form an extrusion channel.

[0008] The radial floating sleeve is fixedly provided with end face sliding seals at its front and rear ends respectively. The radial floating sleeve abuts against the end faces of the liquid supply and diversion assembly and the rigid shaping mold base through the end face sliding seals. An elastic damping matrix is ​​fixed between the outer wall of the radial floating sleeve and the inner wall of the machine head housing.

[0009] Pressure sensing units are arranged in a circumferential array on the head housing, and the detection end of the pressure sensing unit is embedded in the elastic damping matrix.

[0010] The outer circumferential array of the head housing is provided with pneumatic excitation components corresponding to the positions of the pressure sensing units; the outer side of the head housing is also fitted with an air supply control assembly, which is electrically connected to each pressure sensing unit and configured to selectively conduct the air intake path of the corresponding pneumatic excitation component according to the pressure sensing signal.

[0011] The exhaust path of the pneumatic vibration assembly is connected to a bypass buffer pipe, and the output end of the bypass buffer pipe extends and connects to the cable outlet end behind the rigid shaping mold base.

[0012] Preferably, the outer wall of the rigid guide die core has a tapered conical surface, the inner wall of the radial floating sleeve has a tapered flared surface, and the radial cross-sectional area of ​​the extrusion channel decreases along the extrusion direction; the radial floating sleeve is configured to compress the elastic damping matrix on the corresponding side to generate radial offset limiting when subjected to asymmetrical radial thrust inside the fluid.

[0013] Preferably, the inner diameter of the end face sliding seal located at the rear end of the radial floating sleeve is greater than the outlet inner diameter of the radial floating sleeve and less than the inlet inner diameter of the rigid shaping mold base; the diameter difference between the inlet inner diameter of the rigid shaping mold base and the outlet inner diameter of the radial floating sleeve is greater than the maximum radial stroke of the radial floating sleeve compressing the elastic damping matrix.

[0014] Preferably, the gas supply control assembly includes a controller, a distribution collar, an addressing collar, a transition gas chamber, a deflection drive motor, gears, an internal gear ring, and a gas pump, wherein the controller is signal-connected to each pressure sensing unit;

[0015] The distribution collar is fixedly sleeved on the outside of the head housing, the addressing ring is rotatably sleeved on the outside of the distribution collar, and the transition air chamber is opened in the addressing ring and used to connect to an external air source.

[0016] The deflection drive motor is fixedly mounted outside the head housing. The output shaft of the deflection drive motor is fixedly connected to the gear and is driven by the gear meshing with the internal gear ring fixed on the addressing ring. The transition air chamber is provided with an exhaust port. The exhaust port is configured to be coaxially aligned and connected with the air intake of the corresponding pneumatic excitation component through the rotation of the addressing ring. The air pump is mounted on the addressing ring and the air outlet of the air pump faces into the transition air chamber.

[0017] The inner wall of the distribution collar is provided with an annular locking protrusion, and the inner side of the addressing rotating ring is provided with a corresponding annular groove. The distribution collar and the addressing rotating ring are axially limited and rotated through the cooperation of the locking protrusion and the annular groove. A dynamic sealing gasket is embedded on the mating surface of the distribution collar and the addressing rotating ring.

[0018] Preferably, the pneumatic vibration assembly includes a guide cylinder radially fixed to the head housing, a piston slidably fitted inside the guide cylinder, a hammer rod coaxially connected to the bottom of the piston, a fixing ring fixed in the guide cylinder, and a return spring connected between the piston and the fixing ring.

[0019] The elastic damping matrix has a pre-reserved channel for the hammer rod to pass through along the radial direction, and the end of the hammer rod is directly opposite the outer wall side of the radial floating sleeve; the top of the guide cylinder is connected to the distribution ring, and the side wall of the guide cylinder has a breathing pressure relief hole.

[0020] Preferably, a pulse reversing valve is connected between the transition gas chamber and the bypass buffer pipeline;

[0021] The pulse reversing valve includes a hollow valve body and a valve core rotatably embedded in the valve body, the valve core being driven by a reversing drive motor.

[0022] The valve core is radially provided with a through hole penetrating one end of the valve core; the valve core is configured to periodically connect or disconnect the through hole from the inlet and outlet of the valve body as the commutation drive motor rotates.

[0023] Preferably, it also includes a continuous crosslinking component disposed behind the rigid shaping mold base;

[0024] The continuous crosslinking assembly includes a fixed sleeve and a crosslinking tube coaxially inserted therein; the inlet end of the crosslinking tube is fixed to a rigid shaping mold base;

[0025] The output end of the bypass buffer pipeline is connected to a conductive ring, and an assembly ring is fixedly sleeved on the outside of the fixed sleeve. The conductive ring is rotatably sleeved in the assembly ring, and the conductive ring and the assembly ring form a communicating chamber. The bypass buffer pipeline is connected to the communicating chamber through the conductive ring.

[0026] The inner wall of the inlet end of the crosslinking tube is provided with an annular cavity, and a spray ring plate is embedded in the annular cavity. The spray ring plate is provided with air guide holes arranged in a circumferential array. The inner wall of the fixed tube sleeve is provided with an air guide pipe. The annular cavity is connected to the communicating chamber through the air guide pipe.

[0027] Preferably, the commutation drive motor is electrically connected to the controller and is configured with a normally open station with stop and a continuously rotating station;

[0028] In the normally open stop position, the through hole of the gas distribution valve core is kept connected to the inlet and outlet of the valve body, and the airflow passes through the bypass buffer pipe directly to the connecting chamber;

[0029] In the continuous rotating position, the valve core rotates at high speed and periodically cuts off the exhaust to the bypass buffer line to establish a pulse excitation pressure that overcomes the return spring in the transition air chamber and guide cylinder.

[0030] Preferably, at least three baffles are fixed axially between the outer wall of the crosslinking tube and the inner wall of the fixed sleeve to axially isolate the outer annular space of the crosslinking tube into an independent first crosslinking reaction zone and a second cooling zone; the crosslinking tube has an external high-temperature and high-pressure crosslinking gas input groove on the tube wall of the first crosslinking reaction zone, and the outer wall of the fixed sleeve is fixed with an air inlet pipe communicating with the first crosslinking reaction zone.

[0031] A photovoltaic cable with a continuous cross-linked insulation layer includes a conductor, a cross-linked insulation layer covering the outside of the conductor, and an outer sheath disposed outside the cross-linked insulation layer, characterized in that:

[0032] The cross-linked insulating layer is a continuous cross-linked insulating layer based on a polyolefin system, and its preparation raw materials include at least a polyolefin matrix resin, a cross-linking agent, an anti-heat aging agent, and a composite functional component.

[0033] The composite functional component is selected from at least one of surface-modified inorganic mineral fillers, submicron-sized particle fillers, or polymer compatibilizers with polar functional groups.

[0034] The continuous cross-linked insulation layer is formed continuously along the cable axis and exhibits a gradient cross-linking structure with cross-linking density decreasing from the inside to the outside in the radial thickness direction, so as to form a load-bearing area on the side near the conductor and a stress relief area on the side near the outer sheath, and the cross-linking density of the load-bearing area is greater than that of the stress relief area.

[0035] The continuous cross-linked insulation layer is an integrated seamless homogeneous tubular structure formed by adaptive pressure equalization and shaping buffer extrusion process, with equal circumferential wall thickness on the same radial cross section; and the interior of the continuous cross-linked insulation layer and its interface with the conductor are both non-microporous foamed dense phase structures.

[0036] The beneficial effects of this invention are as follows:

[0037] 1. This invention sets a radial floating sleeve between the liquid supply and diversion assembly and the rigid forming die, and uses an elastic damping matrix to radially support and limit it. At the same time, it uses end face sliding seals to achieve dynamic sealing of the front and rear end faces, so that the extrusion channel remains closed and continuous under the condition of allowing a small amount of radial floating. When the difference in circumferential resistance causes asymmetrical radial thrust, the radial floating sleeve can generate a corresponding radial offset and change the local channel gap, thereby passively balancing the circumferential pressure distribution, reducing the probability of insulation layer eccentricity and circumferential wall thickness fluctuation, and improving the molding consistency during continuous extrusion.

[0038] 2. This invention arranges pressure sensing units in a circumferential array on the head housing and embeds their detection ends in an elastic damping matrix, so that the circumferential compressive stress change caused by sleeve offset can be sensed in real time. In conjunction with the addressing and conduction structure of the air supply control assembly, the air source can be selectively conducted to the corresponding pneumatic excitation component according to the orientation, thereby transforming the "circumferential abnormal orientation" into a "locatable and executable" processing object, reducing the frequency of relying on manual experience judgment and shutdown for troubleshooting.

[0039] 3. This invention, by setting up a pneumatic excitation component and using a pulse reversing valve to realize the periodic opening and closing of the air path, forms a pulsed air pressure in the guide cylinder that can drive the piston to reciprocate. The hammer rod performs short-stroke disturbance and knocking on the outer wall of the radial floating sleeve. When local resistance is abnormal or material retention tends to occur, mechanical disturbance can be applied to the corresponding position to promote local flow recovery and pressure return to equilibrium, thereby improving the stability of long-term continuous extrusion process and reducing the cumulative risk of outer diameter fluctuation and wall thickness unevenness.

[0040] 4. This invention uses a bypass buffer pipe to guide the exhaust gas from the pneumatic excitation assembly to the cable outlet and further connect it to the continuous cross-linking assembly. In conjunction with the circumferential array of air guide holes in the conducting ring, connecting chamber, air guide pipe, and injection ring plate, a circumferentially uniform gas-enclosed environment is formed at the inlet section of the cross-linking pipe. This gas environment provides a relatively stable gas pressure boundary for the outer surface of the insulation layer and helps to remove volatile gases released during the cross-linking or extrusion process, thereby reducing the risk of micropore defects in the insulation layer and its interface with the conductor, and improving the density and interface stability of the insulation layer.

[0041] 5. This invention utilizes a partition in the continuous cross-linking assembly to divide the external annular space into a first cross-linking reaction zone and a second cooling zone. A high-temperature, high-pressure cross-linking gas is introduced into the first cross-linking reaction zone, and heat exchange and cooling are implemented in the cooling zone. This allows for continuous connection and controllable thermal history between cross-linking and cooling of the cable. Combined with adaptive pressure equalization and shaping buffer extrusion processes, a continuous cross-linked insulation layer of a polyolefin system formed along the axial direction can be obtained. This layer has a uniform circumferential wall thickness on the same cross-section and forms a gradient structure with gradually decreasing cross-linking density from the inside to the outside in the radial thickness direction. This creates a load-bearing zone near the conductor and a stress-relieving zone near the outer sheath, balancing support and stress release requirements in a single-layer seamless structure and reducing interface uncertainties caused by multi-layer structures. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the present invention;

[0043] Figure 2 This is a cross-sectional view of the present invention;

[0044] Figure 3 This is a cross-sectional view of the air supply control assembly and pneumatic vibration excitation component of the present invention;

[0045] Figure 4 for Figure 3 Enlarged structural diagram at point A;

[0046] Figure 5 for Figure 3 Enlarged structural diagram at point B;

[0047] Figure 6 This is a cross-sectional view of the head housing and radial floating sleeve of the present invention;

[0048] Figure 7 An exploded view of the allocation ring and addressing loop of the present invention;

[0049] Figure 8 This is a cross-sectional view of the continuous cross-linking component of the present invention;

[0050] Figure 9 This is a schematic diagram of the radial cross-section hierarchy of the photovoltaic cable product of the present invention;

[0051] In the diagram: 1. Head housing; 2. Liquid supply diversion assembly; 3. Rigid shaping mold base; 4. Rigid guide mold core; 5. Radial floating sleeve; 6. End face sliding seal; 7. Elastic damping matrix; 8. Pressure sensing unit; 9. Pneumatic vibration assembly; 901. Guide cylinder; 902. Piston; 903. Hammer rod; 904. Return spring; 905. Fixed ring; 10. Air supply control assembly; 1001. Distribution collar; 1002. Addressing rotating ring; 1003. Transition air chamber; 1004. Deflection drive motor; 1005. Gear; 1006. Internal gear ring; 1007. Air pump; 11. Bypass buffer line ; 12. Shrinking conical surface; 13. Gradually narrowing flared surface; 14. Reserved channel; 15. Breathing pressure relief hole; 16. Pulse reversing valve; 1601. Valve body; 1602. Gas distribution valve core; 1603. Reversing drive motor; 1604. Through hole; 17. Continuous cross-linking assembly; 1701. Fixed sleeve; 1702. Cross-linking tube; 18. Conducting ring; 19. Assembly ring; 20. Injection ring plate; 21. Air guide hole; 22. Air guide tube; 23. Partition plate; 24. Air groove; 25. Annular cavity; 26. Conductor; 27. Continuous cross-linking insulation layer; 2701. Bearing area; 2702. Stress relief area; 28. Outer protective layer. Detailed Implementation

[0052] One or more embodiments of the present invention will now be described with reference to the accompanying drawings. To avoid ambiguity in the understanding of terms, "front end" refers to the side near the liquid supply diversion assembly 2, "rear end" refers to the side near the rigid shaping mold base 3 and the cable outlet end; "radial" refers to the direction perpendicular to the extrusion direction, and "circumferential" refers to the direction around the extrusion center axis.

[0053] like Figures 1-9 As shown, the extrusion shaping processing device is generally supported by the die head housing 1. Inside the die head housing 1, the liquid supply and diversion assembly 2 and the rigid shaping die base 3 are arranged sequentially along the extrusion direction. The rigid guide die core 4 is coaxially fixed inside the die head housing 1. After entering from the front end, the conductor 26 passes through the die head housing 1 along the central channel of the rigid guide die core 4 and exits from the rear end of the rigid shaping die base 3.

[0054] A radial floating sleeve 5 is fitted between the liquid supply and diversion assembly 2 and the rigid shaping mold base 3. An annular extrusion channel is formed between the inner wall of the radial floating sleeve 5 and the outer wall of the rigid guide mold core 4. The liquid supply and diversion assembly 2 distributes the molten plastic liquid output from the extruder in a circumferential direction and sends it into the annular extrusion channel, so that the molten plastic liquid forms an annular coating flow in the extrusion direction. Under the constraint of the rigid guide mold core 4 on the position of the conductor 26, it continuously coats the outer surface of the conductor 26 to form an uncrosslinked insulating layer blank.

[0055] The front and rear ends of the radial floating sleeve 5 are respectively fixed with end face sliding seals 6. The end face sliding seals 6 are respectively in contact with the rear end face of the liquid supply and diversion assembly 2 and the front end face of the rigid shaping mold base 3, so as to maintain the end face sealing of the annular extrusion channel at the front and rear ends while allowing the sleeve 5 to float slightly radially. As one embodiment, the end face sliding seal 6 may include a wear-resistant sealing ring and an elastic pre-tightening structure. The material of the wear-resistant sealing ring may be polytetrafluoroethylene, filled polytetrafluoroethylene, or wear-resistant composite material containing graphite; the elastic pre-tightening structure may be a spring ring or a wave spring sheet, used to compensate for the end face gap changes caused by temperature rise, wear, and assembly tolerance, thereby maintaining a stable contact state.

[0056] An elastic damping matrix 7 is provided between the head housing 1 and the radial floating sleeve 5. The outer side of the elastic damping matrix 7 is fixedly connected to the head housing 1, and the inner side abuts or is bonded to the outer wall of the radial floating sleeve 5 to provide radial support, limiting and damping. The elastic damping matrix 7 can be an integral annular elastomer or it can be composed of multiple elastic blocks assembled in circumferential segments. Its material can be silicone rubber, fluororubber or heat-resistant elastomer composite material, and its hardness and thickness can be selected according to the maximum allowable radial stroke of the sleeve 5 and the required damping characteristics.

[0057] To achieve a smoother molding flow, in some embodiments, a contraction cone surface 12 is formed on the outer wall of the rigid guide mold core 4 near the outlet end, and a gradually tapering horn surface 13 is formed on the inner wall of the radial floating sleeve 5, so that the radial cross-sectional area of ​​the annular extrusion channel gradually decreases along the extrusion direction. This tapering structure causes the molten plastic liquid to gradually converge during axial advancement and form a relatively stable annular velocity distribution before entering the rigid shaping mold base 3.

[0058] In some embodiments, the end face sliding seal 6 located at the rear end of the radial floating sleeve 5 is provided with an inner hole, the diameter of which is larger than the outlet inner diameter of the radial floating sleeve 5 and smaller than the inlet inner diameter of the rigid shaping mold base 3. At the same time, the diameter difference between the inlet inner diameter of the rigid shaping mold base 3 and the outlet inner diameter of the radial floating sleeve 5 is greater than the maximum radial stroke of the radial floating sleeve 5 under the action of the elastic damping matrix 7. Thus, when the sleeve 5 experiences the maximum allowable offset, its outlet is still within the envelope of the inlet of the shaping mold base 3, allowing the molten plastic liquid to continuously enter the shaping mold base 3 without causing flow cut-off or obvious step stagnation.

[0059] Pressure sensing units 8 are arranged in a circumferential array around the outer periphery of the head housing 1. The detection end of the pressure sensing unit 8 is embedded in the elastic damping matrix 7. The pressure sensing unit 8 is used to sense the compressive stress changes of the elastic damping matrix 7 in all directions, thereby indirectly reflecting the offset direction and degree of the radial floating sleeve 5. As one embodiment, the pressure sensing unit 8 can be a strain gauge type, piezoresistive type, or piezoelectric sensor. To facilitate circumferential comparison, the number of pressure sensing units 8 can be 6, 8, or 10 and evenly distributed, and arranged circumferentially in correspondence with the pneumatic excitation assembly 9 described later.

[0060] An air supply control assembly 10 is installed on the outside of the head housing 1 and is signal-connected to each pressure sensing unit 8. The air supply control assembly 10 is used to "address" the external air source to the pneumatic excitation assembly 9 in the selected direction in a circumferential manner. As shown in the figure, the air supply control assembly 10 may include a distribution collar 1001 fixed on the outside of the head housing 1, an addressing rotating ring 1002 that can rotate relative to the distribution collar 1001, and a transition air chamber 1003 disposed in the addressing rotating ring 1002. The transition air chamber 1003 is connected to the external air source and has an exhaust port. A deflection drive motor 1004 meshes with an internal gear ring 1006 fixed on the addressing rotating ring 1002 through a gear 1005, driving the addressing rotating ring 1002 to rotate, so that the exhaust port is sequentially aligned and connected with the air intake path of the pneumatic excitation assembly 9 in different directions during the rotation. The distribution collar 1001 and the addressing rotating ring 1002 can be axially limited through the snap-fit ​​and the ring groove, and a dynamic sealing gasket is provided on the mating surface to reduce leakage.

[0061] The air pump 1007 is installed on the addressing ring 1002, and the air outlet of the air pump 1007 faces the transition air chamber 1003. Specifically, the air pump 1007 provides pressurized airflow.

[0062] In actual operation, the addressing ring 1002 only intermittently deflects when an abnormal pressure occurs in a specific location. To ensure the power supply to the air pump 1007, the air pump 1007 is connected to the power source via an externally extended flexible spiral cable (not shown in the figure). Simultaneously, the controller is equipped with anti-entanglement addressing logic: an initial zero position is set, and the maximum unidirectional deflection stroke of the addressing ring 1002 is limited to ±180 degrees (or ±360 degrees); when the required addressing location exceeds the unidirectional stroke, the deflection drive motor 1004 rotates in the opposite direction to the target position. Through this intermittent, limited-angle positioning deflection mode, combined with the elastic extension and retraction of the flexible spiral cable, a stable power supply to the air pump 1007 can be achieved.

[0063] The pneumatic vibration assembly 9 is fixed to the outside of the head housing 1 in a circumferential array. Its structure may include a guide cylinder 901, a piston 902 that slides within the guide cylinder 901, a hammer rod 903 coaxially connected to the bottom of the piston 902, and a return spring 904 connected between the piston 902 and the fixed ring 905. A pre-drilled channel 14 is provided radially on the elastic damping matrix 7 for the hammer rod 903 to pass through. The end of the hammer rod 903 faces the outer wall of the radial floating sleeve 5. When the corresponding position is supplied with air by the air supply control assembly 10, the piston 902 moves inward against the return spring 904 under the action of air pressure and drives the hammer rod 903 to perform one or more short-stroke impacts on the outer wall of the sleeve 5. After the air supply stops or the pressure is released, the return spring 904 pushes the piston 902 and the hammer rod 903 to return to their original positions. A breathing pressure relief hole 15 may be provided on the side wall of the guide cylinder 901 for local pressure relief and air exchange during the piston reciprocating process.

[0064] The exhaust path of the pneumatic vibration assembly 9 is connected to the bypass buffer line 11, and the output end of the bypass buffer line 11 extends to the cable outlet end behind the rigid shaping mold base 3. The bypass buffer line 11 can be used to collect exhaust gas, or it can be used as a gas introduction channel in the subsequent continuous crosslinking section. To facilitate mode switching, a pulse reversing valve 16 can be connected between the transition gas chamber 1003 and the bypass buffer line 11.

[0065] The pulse reversing valve 16 may include a valve body 1601 and a valve core 1602 rotatably disposed within the valve body 1601. The valve core 1602 is driveably connected to a reversing drive motor 1603. A through hole 1604 is provided on the valve core 1602. When the reversing drive motor 1603 drives the valve core 1602 to rotate, the through hole 1604 and the inlet and outlet of the valve body 1601 are alternately aligned and connected or misaligned and disconnected during the rotation cycle. Thus, the reversing drive motor 1603 can be configured with two working positions: one is a normally open position where the through hole 1604 is kept connected to the inlet and outlet of the valve body 1601, thereby maintaining continuous air supply through the bypass buffer line 11; the other is a continuous rotation position where the air supply through the bypass buffer line 11 is periodically cut off, forming a pulse air pressure in the transition air chamber 1003 and the guide cylinder 901 that can drive the piston 902 to reciprocate.

[0066] The commutation drive motor 1603 is fixed to the addressing ring 1002 by a support arm, and works with the valve body 1601 fixed to the addressing ring 1002 to maintain stable following deflection.

[0067] As shown in the figure, the device also includes a continuous crosslinking component 17 located behind the rigid shaping mold base 3; the continuous crosslinking component 17 includes a fixed sleeve 1701 and a crosslinking tube 1702 coaxially inserted in the fixed sleeve 1701. The inlet end of the crosslinking tube 1702 is fixed relative to the outlet end of the rigid shaping mold base 3, so that the shaped cable enters the crosslinking tube 1702 axially for continuous processing.

[0068] The output end of the bypass buffer line 11 can be connected to the continuous crosslinking assembly 17 through the conductive ring 18. The assembly ring 19 can be fixedly sleeved on the outside of the fixed sleeve 1701, and the conductive ring 18 and the assembly ring 19 form a communicating chamber; the conductive ring 18 and the assembly ring 19 can adopt a sealed rotational fit (e.g., a rotary joint or a coaxial sealing surface) to accommodate assembly deviations, thermal expansion differences or relative rotation and maintain the continuity of the gas path.

[0069] Furthermore, to ensure that the bypass buffer line 11 can stably and without interference deflect with the addressing ring 1002, in this embodiment, the bypass buffer line 11 adopts a rigid pipe. The front end of the rigid pipe is fixedly connected to the valve body of the pulse reversing valve 16 and deflects accordingly, while its rear end is fixedly connected to the conducting ring 18. At the same time, outside the head housing 1 and the continuous crosslinking assembly 17, there is a non-interference annular clearance space reserved to meet the maximum deflection stroke (e.g., ±180 degrees) of the rigid pipe.

[0070] During the azimuth deflection of the bypass buffer line 11 driven by the addressing ring 1002, the fixed assembly ring 19 provides reliable radial support for the circumferential sliding of the conduction ring 18. Thus, with the rigid fixation at both ends and the rotational support, the bypass buffer line 11 is ensured to maintain a stable spatial deflection and parking posture during frequent circumferential addressing operations, fundamentally avoiding the risks of pipeline twisting, entanglement and external mechanical interference.

[0071] An annular cavity 25 is provided on the inner wall of the inlet end of the crosslinking tube 1702. A jetting ring plate 20 is embedded in the annular cavity 25, and air guide holes 21 are arranged in a circumferential array on the jetting ring plate 20. An air guide pipe 22 is provided on the inner wall of the fixed sleeve 1701 to connect the connecting chamber and the annular cavity 25. When the bypass buffer line 11 is continuously ventilated in the normally open position, the gas enters the connecting chamber through the conducting ring 18, then enters the annular cavity 25 through the air guide pipe 22, and is sprayed into the crosslinking tube 1702 through the air guide holes 21. A circumferentially uniform gas-enclosed environment is formed in the inlet section of the crosslinking tube 1702 to provide a stable gas pressure boundary for the outer surface of the cable and to remove volatile gases.

[0072] To achieve continuous connection between crosslinking and cooling, in some embodiments, at least three baffles 23 are axially arranged between the outer wall of the crosslinking tube 1702 and the inner wall of the fixed sleeve 1701, dividing the annular space outside the crosslinking tube 1702 into at least a first crosslinking reaction zone and a second cooling zone. The first crosslinking reaction zone can be supplied with high-temperature, high-pressure crosslinking gas through an inlet pipe on the outer wall of the fixed sleeve 1701. A gas groove 24 for introducing the crosslinking gas is provided on the tube wall corresponding to the first crosslinking reaction zone, allowing the crosslinking gas to enter the interior of the crosslinking tube 1702 and contact the outer surface of the cable. The second cooling zone can exchange heat through a cooling jacket or cooling medium channel on the outer wall of the fixed sleeve 1701 to achieve temperature drop and dimensional stability after the cable passes through. Furthermore, the end of the continuous crosslinking assembly 17 has an exhaust area to maintain the dynamic pressure balance inside the crosslinking tube 1702 and stably discharge the gas carrying volatile components.

[0073] Based on the above apparatus, a photovoltaic cable with a continuous cross-linked insulation layer can be obtained. The photovoltaic cable includes a conductor 26, a cross-linked insulation layer covering the outside of the conductor 26, and an outer sheath 28 located outside the cross-linked insulation layer. The cross-linked insulation layer is a continuous cross-linked insulation layer 27, and the raw materials of the continuous cross-linked insulation layer 27 include at least a polyolefin matrix resin, a cross-linking agent, an anti-heat aging agent, and a composite functional component; the composite functional component can be selected from at least one of surface-modified inorganic mineral fillers, submicron-sized particulate fillers, or polymer compatibilizers with polar functional groups.

[0074] In a feasible preparation process, the above raw materials can first be dry-premixed or melt-blended and granulated to obtain extrusion masterbatch; the extruder melts and plasticizes the masterbatch and feeds it into the liquid supply and distribution assembly 2, where the molten plastic liquid continuously coats the conductor 26 in the annular extrusion channel to form an insulation layer preform; the cable then enters the rigid shaping die 3 to complete the outer diameter shaping, and then enters the crosslinking tube 1702 to complete continuous crosslinking and subsequent cooling and shaping. The residence time of the cable in the crosslinking tube 1702 can be determined by the effective length L of the crosslinking tube 1702 and the traction line speed v (t=L / v), and the thermal history required for the crosslinking reaction can be matched accordingly.

[0075] A continuous cross-linked insulation layer 27 is formed continuously along the cable axis. In some embodiments, by coordinating and controlling the thermal and cooling boundaries, the continuous cross-linked insulation layer 27 forms a gradient structure in the radial thickness direction, with the cross-linking density decreasing progressively from the inside to the outside. Furthermore, the photovoltaic cable produced by this device has a unique gradient cross-linking structure. The formation mechanism of this structure is as follows: when the extruded and coated cable enters the cross-linking tube 1702, the area inside that is in close contact with the conductor is affected by the extremely high latent heat of the melt itself, resulting in a very fast cross-linking reaction rate and forming a high-cross-linking-density inner bearing area 2701; while the outer surface of the insulation layer is enveloped and convectively cooled by a relatively low-temperature buffer nitrogen gas curtain introduced by the bypass buffer pipe 11, and its surface temperature is slightly lower than that of the inner layer, resulting in a relatively slow cross-linking reaction rate on the outside, thus naturally forming a relatively low-cross-linking-density outer stress relief area 2702. The thermodynamic temperature gradient facilitated by the gas pressure buffer system endows the cable insulation layer with excellent resistance to mechanical bending and thermal cycling stress release capabilities.

[0076] To ensure uniform circumferential wall thickness at the same cross section, passive pressure equalization and active excitation can be used with the help of the radial floating sleeve 5 supported by the elastic damping matrix 7: when the circumferential pressure is uneven, the sleeve 5 is biased to change the local flow channel gap, and with the orientation addressing and knocking of the pressure sensing unit 8 and the pneumatic excitation component 9, the local abnormal resistance is disturbed and released, and the circumferential pressure is brought back to equilibrium; the molten coating layer then enters the rigid shaping mold 3 and is forcibly sized, thereby forming a tubular structure with uniform circumferential wall thickness on the shaping section.

[0077] To reduce the risk of micropores within the insulation layer and at its interface with conductor 26, a stable external gas pressure can be maintained at the inlet section of the crosslinking pipe 1702 through a circumferentially uniform gas environment provided by the spray ring plate 20, and a continuous pressure boundary can be formed in the first crosslinking reaction zone through crosslinking gas. Simultaneously, the content of volatile components is controlled and necessary venting is performed during the formulation mixing and extrusion plasticizing stages. As a result, the insulation layer appears as a continuous, dense phase under microscopic observation, without the formation of through-holes.

[0078] The working principle and operation process of this invention can be summarized as follows:

[0079] First, conductor 26 passes through the center of rigid guide mold core 4. Molten plastic liquid is distributed by liquid supply and diversion component 2 and enters the annular extrusion channel formed by rigid guide mold core 4 and radial floating sleeve 5 to form a continuous coating on conductor 26.

[0080] Secondly, if circumferential pressure is uneven in the extrusion channel, the radial floating sleeve 5 will be biased in the elastic damping matrix 7 and change the local channel gap. The pressure sensing unit 8 will collect compression stress signals in all directions, and the controller will drive the air supply control assembly 10 to connect the air source addressing to the corresponding pneumatic excitation component 9.

[0081] Then, the reversing drive motor 1603 causes the pulse reversing valve 16 to open and close periodically in the continuous rotation position, forming a pulse air pressure in the guide cylinder 901 to drive the hammer rod 903 to reciprocate and disturb the outer wall of the sleeve 5.

[0082] Next, the wrapped cable enters the rigid shaping mold 3 to complete the sizing and then enters the cross-linking pipe 1702. The cross-linking gas introduced in the first cross-linking reaction zone and the bypass gas introduced in the inlet section together form a stable gas environment. After the cable completes continuous cross-linking in the cross-linking pipe 1702, it enters the second cooling zone to complete the cooling and shaping and is then output.

Claims

1. An extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer, characterized in that, It includes a die head housing (1) and a liquid supply and diversion assembly (2) and a rigid shaping die base (3) arranged sequentially inside the die head housing (1) along the extrusion direction. A rigid guide mold core (4) is coaxially fixed inside the head housing (1). A radial floating sleeve (5) is sleeved between the liquid supply diversion assembly (2) and the rigid shaping mold base (3). The inner wall of the radial floating sleeve (5) and the outer wall of the rigid guide mold core (4) enclose each other to form an extrusion channel. The radial floating sleeve (5) is fixedly provided with end face sliding seals (6) at its front and rear ends respectively. The radial floating sleeve (5) abuts against the end face of the liquid supply diversion assembly (2) and the rigid shaping mold base (3) through the end face sliding seals (6). An elastic damping matrix (7) is fixed between the outer wall of the radial floating sleeve (5) and the inner wall of the machine head housing (1). Pressure sensing units (8) are arranged in a circumferential array on the head housing (1), and the detection end of the pressure sensing unit (8) is embedded in the elastic damping matrix (7). The outer circumferential array of the head housing (1) is provided with pneumatic excitation components (9) corresponding to the positions of the pressure sensing units (8); the outer side of the head housing (1) is also fitted with an air supply control assembly (10), which is electrically connected to each pressure sensing unit (8) and configured to select one to conduct the air intake path of the corresponding pneumatic excitation component (9) according to the pressure sensing signal; The exhaust path of the pneumatic excitation assembly (9) is connected to a bypass buffer pipe (11), and the output end of the bypass buffer pipe (11) extends and connects to the cable outlet end behind the rigid shaping mold base (3).

2. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 1, characterized in that, The outer wall of the rigid guide core (4) has a tapered conical surface (12), the inner wall of the radial floating sleeve (5) has a tapered horn surface (13), and the radial cross-sectional area of ​​the extrusion channel decreases along the extrusion direction; the radial floating sleeve (5) is configured to compress the elastic damping matrix (7) on the corresponding side to generate radial offset limit when subjected to asymmetrical radial thrust inside the fluid.

3. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 1, characterized in that, The inner diameter of the end face sliding seal (6) located at the rear end of the radial floating sleeve (5) is greater than the outlet inner diameter of the radial floating sleeve (5) and less than the inlet inner diameter of the rigid shaping mold base (3); the diameter difference between the inlet inner diameter of the rigid shaping mold base (3) and the outlet inner diameter of the radial floating sleeve (5) is greater than the maximum radial stroke of the radial floating sleeve (5) compressing the elastic damping matrix (7).

4. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 1, characterized in that, The gas supply control assembly (10) includes a controller, a distribution collar (1001), an addressing collar (1002), a transition gas chamber (1003), a deflection drive motor (1004), a gear (1005), an internal gear ring (1006), and a gas pump (1007). The controller is signal-connected to each pressure sensing unit (8). The distribution collar (1001) is fixedly sleeved on the outside of the head housing (1), the addressing ring (1002) is rotatably sleeved on the outside of the distribution collar (1001), and the transition air chamber (1003) is opened in the addressing ring (1002) and used to connect to the external air source; The deflection drive motor (1004) is fixedly installed outside the head housing (1). The output shaft of the deflection drive motor (1004) is fixedly connected to the gear (1005) and is driven by the gear (1005) meshing with the internal gear ring (1006) fixed on the addressing ring (1002). The transition air chamber (1003) is provided with an exhaust port. The exhaust port is configured to be coaxially aligned and connected with the air intake of the corresponding pneumatic excitation component (9) through the rotation of the addressing ring (1002). The air pump (1007) is installed on the addressing ring (1002) and the air outlet of the air pump (1007) faces into the transition air chamber (1003). The inner wall of the distribution collar (1001) is provided with an annular locking protrusion, and the inner side of the addressing rotating ring (1002) is provided with a corresponding annular groove. The distribution collar (1001) and the addressing rotating ring (1002) are axially limited and rotated through the cooperation of the locking protrusion and the annular groove. A dynamic sealing gasket is embedded on the mating surface of the distribution collar (1001) and the addressing rotating ring (1002).

5. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 4, characterized in that, The pneumatic vibration assembly (9) includes a guide cylinder (901) radially fixed to the head housing (1), a piston (902) slidably fitted inside the guide cylinder (901), a hammer rod (903) coaxially connected to the bottom of the piston (902), a retaining ring (905) fixed in the guide cylinder (901), and a return spring (904) connected between the piston (902) and the retaining ring (905). The elastic damping matrix (7) has a pre-reserved channel (14) for the hammer rod (903) to pass through along the radial direction. The end of the hammer rod (903) is directly opposite the outer wall of the radial floating sleeve (5). The top of the guide cylinder (901) is connected to the distribution ring (1001). The side wall of the guide cylinder (901) has a breathing pressure relief hole (15).

6. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 5, characterized in that, A pulse reversing valve (16) is connected between the transition gas chamber (1003) and the bypass buffer line (11). The pulse reversing valve (16) includes a hollow valve body (1601) and a valve core (1602) rotatably embedded in the valve body (1601). The valve core (1602) is connected to a reversing drive motor (1603). The valve core (1602) is radially provided with a through hole (1604) penetrating one end of the valve core (1602); the valve core (1602) is configured to periodically connect or disconnect the through hole (1604) from the inlet and outlet of the valve body (1601) as the commutation drive motor (1603) rotates.

7. The extrusion forming apparatus for photovoltaic cables with a continuous cross-linked insulation layer according to claim 1, characterized in that, It also includes a continuous crosslinking component (17) disposed behind the rigid shaping mold base (3); The continuous crosslinking component (17) includes a fixed sleeve (1701) and a crosslinking tube (1702) coaxially inserted therein; the inlet end of the crosslinking tube (1702) is fixed at the rigid shaping mold base (3); The output end of the bypass buffer pipeline (11) is connected to a conductive ring (18), and an assembly ring (19) is fixedly sleeved on the outside of the fixed sleeve (1701). The conductive ring (18) is sealed and rotated in the assembly ring (19). The conductive ring (18) and the assembly ring (19) form a communicating chamber. The bypass buffer pipeline (11) is connected to the communicating chamber through the conductive ring (18). The inner wall of the inlet end of the crosslinking tube (1702) is provided with an annular cavity (25), and a spray ring plate (20) is embedded in the annular cavity (25). Air guide holes (21) are arranged in a circumferential array on the spray ring plate (20). The inner wall of the fixed tube sleeve (1701) is provided with an air guide pipe (22). The annular cavity (25) is connected to the connecting chamber through the air guide pipe (22).

8. The extrusion forming apparatus for a photovoltaic cable with a continuous cross-linked insulation layer according to claim 6, characterized in that, The commutation drive motor (1603) is electrically connected to the controller and is equipped with a normally open stop position and a continuously rotating position. In the normally open position where the operation is stopped, the through hole (1604) of the gas distribution valve core (1602) is connected to the inlet and outlet of the valve body (1601), and the airflow passes through the bypass buffer pipe (11) directly to the connecting chamber; In the continuous rotating position, the valve core (1602) rotates at high speed and periodically cuts off the exhaust to the bypass buffer line (11) to establish a pulse excitation pressure that overcomes the return spring (904) in the transition air chamber (1003) and the guide cylinder (901).

9. The extrusion forming apparatus for a photovoltaic cable with a continuous cross-linked insulation layer according to claim 7, characterized in that, At least three baffles (23) are fixed axially between the outer wall of the crosslinking tube (1702) and the inner wall of the fixed sleeve (1701) to axially isolate the outer annular space of the crosslinking tube (1702) into an independent first crosslinking reaction zone and a second cooling zone; the crosslinking tube (1702) has an external high-temperature and high-pressure crosslinking gas input groove (24) on the tube wall of the first crosslinking reaction zone, and the outer wall of the fixed sleeve (1701) is fixed with an air inlet pipe that communicates with the first crosslinking reaction zone.

10. A photovoltaic cable having a continuous cross-linked insulation layer, comprising a conductor (26), a cross-linked insulation layer covering the outside of the conductor (26), and an outer sheath (28) disposed outside the cross-linked insulation layer, characterized in that: The cross-linked insulating layer is a continuous cross-linked insulating layer based on a polyolefin system (27), and its raw materials include at least a polyolefin matrix resin, a cross-linking agent, an anti-heat aging agent, and a composite functional component; The composite functional component is selected from at least one of surface-modified inorganic mineral fillers, submicron-sized particle fillers, or polymer compatibilizers with polar functional groups. The continuous cross-linked insulation layer (27) is formed continuously along the cable axis and has a gradient cross-linked structure with the cross-linking density decreasing from the inside to the outside in the radial thickness direction, so as to form a bearing area (2701) on the side near the conductor (26) and a stress relief area (2702) on the side near the outer sheath (28), and the cross-linking density of the bearing area (2701) is greater than the cross-linking density of the stress relief area (2702); The continuous cross-linked insulating layer (27) is an integrated seamless homogeneous tubular structure formed by adaptive pressure equalization and shaping buffer extrusion process, with equal circumferential wall thickness on the same radial cross section; and the interior of the continuous cross-linked insulating layer (27) and its interface with the conductor (26) are both non-porous foamed dense phase structures.

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