Transformer high and low voltage winding insulation structure and processing device thereof

Abstract

The application belongs to the technical field of transformers, and particularly relates to a high-low voltage winding insulation structure of a transformer, which is arranged between a high-voltage winding and a low-voltage winding and comprises coaxially arranged, in sequence, an outer insulation cylinder, an inner insulation cylinder and at least one set of gradient dielectric constant insulation components, the gradient dielectric constant insulation components being arranged on the outer wall of the outer insulation cylinder and / or the inner wall of the inner insulation cylinder; the inner wall of the outer insulation cylinder is provided with a plurality of circumferentially uniformly distributed heat dissipation grooves; the gradient dielectric constant insulation components are adopted, the dielectric constants of the three-layer structure are gradually reduced in the direction of the electric field intensity, and the electric field distribution between the high-voltage winding and the low-voltage winding can be effectively homogenized; the heat dissipation grooves are matched with heat conduction strips with 'S' type through heat dissipation air ducts, and the heat exchange path of the cooling medium is prolonged; the outer and inner insulation cylinders are made of nano-silicon dioxide reinforced PA66 material, have high rigidity and high deformation resistance, the outer wall of the inner insulation cylinder is matched and clamped with the inner wall clamping groove of the outer insulation cylinder, and the coaxiality and the overall rigidity of the insulation structure are ensured.

Description

Technical Field

[0001] This invention belongs to the field of transformer technology, specifically relating to an insulation structure for high and low voltage windings of a transformer, and also to a processing device for the insulation structure of high and low voltage windings of a transformer. Background Technology

[0002] During the operation of a power transformer, the insulation structure between the high-voltage and low-voltage windings is the core component that determines the insulation reliability, service life, and operational safety of the transformer. The transformer winding insulation structure not only needs to meet the insulation performance requirements under long-term rated voltage, but also needs to withstand extreme voltage conditions such as lightning strikes and switching impacts. At the same time, it needs to have sufficient mechanical strength to resist the electrodynamic impact under short-circuit conditions, as well as excellent heat dissipation performance to dissipate the Joule heat generated by the winding operation and delay the thermal aging of the insulation.

[0003] Traditional transformer insulation structures mainly employ methods such as oil-paper composite insulation, solid insulation cylinders, and combinations of support bars and corner rings.

[0004] For example, Chinese patent CN121237534A discloses an "insulation and heat dissipation structure for high and low voltage coils and coils of dry-type transformers", which sets up multiple layers of air channel insulation layers arranged radially and circumferentially with arc-shaped air channels on the insulation body, and extends the creepage distance and improves heat dissipation by staggered arrangement of spaced supports.

[0005] However, the insulation structure of traditional transformer high and low voltage windings is mostly homogeneous or simple layered design. Under extreme voltage impact or long-term thermal stress, local field strength concentration is prone to occur, which can lead to partial discharge. It is difficult to meet the requirements of high insulation strength, excellent mechanical support performance and efficient heat dissipation at the same time.

[0006] To address the aforementioned problems, this invention proposes an insulation structure for high and low voltage windings of a transformer and its processing device. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a transformer high and low voltage winding insulation structure and its processing device, which features high insulation reliability, good heat dissipation performance, and reliable and durable mechanical strength.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a transformer high and low voltage winding insulation structure, disposed between a high voltage winding and a low voltage winding coaxially sleeved on the winding body, comprising an outer insulating cylinder, an inner insulating cylinder, and at least one set of gradient dielectric constant insulation components coaxially and sequentially sleeved on the outer wall of the outer insulating cylinder and / or the inner wall of the inner insulating cylinder; The inner wall of the outer insulating cylinder is provided with a plurality of heat dissipation grooves evenly distributed along the circumference, and the heat dissipation grooves pass through both ends of the outer insulating cylinder along the axial direction. The gradient dielectric constant insulation component includes an outer insulating coating, a middle silicone rubber bushing, and an inner insulating coating arranged in sequence. The dielectric constant of the outer insulating coating, the middle silicone rubber bushing, and the inner insulating coating decreases progressively along the direction of decreasing electric field strength.

[0009] As a preferred embodiment of the present invention, the outer wall of the inner insulating cylinder is uniformly provided with a plurality of axially extending ribs along the circumference, and the inner wall of the outer insulating cylinder is provided with a plurality of slots that are adapted to the ribs.

[0010] As a preferred embodiment of the present invention, the heat dissipation groove is provided with a heat-conducting strip, and an "S"-shaped heat dissipation air channel is formed in the heat-conducting strip, and the heat dissipation air channel passes through both ends of the heat-conducting strip along its axial direction.

[0011] As a preferred embodiment of the present invention, the outer insulating coating is an epoxy resin doped with barium titanate ceramic particles, with a relative permittivity of 15-30; the intermediate silicone rubber bushing is an addition-type methyl vinyl silicone rubber, with a relative permittivity of 6-10; and the inner insulating coating is a nano-silica modified polyimide, with a relative permittivity of 2-4.

[0012] As a preferred embodiment of the present invention, both the outer insulating cylinder and the inner insulating cylinder are reinforced PA66 insulating cylinders doped with nano-silica.

[0013] A processing apparatus for high and low voltage winding insulation structure of transformer, used to process the high and low voltage winding insulation structure of transformer as described in any of the above inventions, includes an extruder body, an extrusion tube, a die body, a hopper, a screw conveying mechanism, a diverter box, and a screw extrusion mechanism; The extrusion tube is disposed at the top of the extruder body; The die body is coaxially and sealed to the discharge end of the extrusion tube by a fixing mechanism. The die body includes a flow guide seat, a flow equalization plate, a forming core rod and an outer die cylinder arranged coaxially in sequence. A flow guide hole is provided at the center of the flow guide seat, and a flow guide cone is fixed on the side of the flow equalization plate facing the flow guide hole. Multiple flow equalization holes are provided on the flow equalization plate and are evenly distributed in the circumferential direction to evenly distribute the molten material in the circumferential direction. One end of the forming core rod is fixed with a threaded rod, and the flow equalization plate is provided with a threaded hole that matches the threaded rod. The outer wall of the forming core rod is provided with a first boss for forming a heat dissipation groove, and a forming flow groove is formed between two adjacent first bosses. A second boss for forming a slot is provided in the forming flow groove. The outer mold cylinder is coaxially sleeved on the outer wall of the forming core rod and fixedly connected to the flow equalization plate. A forming flow channel for forming the outer insulating cylinder is formed between the outer mold cylinder and the forming core rod. The hopper is fixed to the top of the extruder body, and the feed inlet of the screw conveyor is connected to the discharge outlet at the bottom of the hopper; The feed inlet of the diversion box is connected to the end outlet of the screw conveyor mechanism. A diversion cone with a conical cross-section is fixed inside the bottom outlet of the diversion box, and the bottom outlet of the diversion box is connected to the feed inlet of the extrusion tube. The spiral extrusion mechanism is coaxially connected to the end of the extrusion tube furthest from the die body.

[0014] As a preferred embodiment of the present invention, the fixing mechanism includes a positioning screw and a nut; Multiple positioning screws are uniformly fixed circumferentially to the outer wall of the extrusion tube outlet end; The guide seat has a positioning hole for the positioning screw to pass through, and the nut is set on the extended end of the positioning screw by means of thread engagement; Rubber sealing rings are provided between the flow guide seat and the extrusion tube, between the flow equalization plate and the flow guide seat, and between the outer mold cylinder and the flow equalization plate.

[0015] As a preferred embodiment of the present invention, the forming core rod includes a flow equalization section and a forming section that are coaxially and integrally connected; The outer wall of the flow equalization section is provided with multiple Archimedes spiral flow channels that are evenly distributed in the circumference. The inlet end of the Archimedes spiral flow channel is connected to the outlet side of the flow equalization plate, and the outlet end is connected to the forming flow channel. The depth of the Archimedes spiral flow channel increases step by step from the inlet end to the outlet end. The first boss and the second boss are disposed on the outer wall of the forming section.

[0016] As a preferred embodiment of the present invention, the spiral conveying mechanism includes a conveying pipe, a rotating shaft, spiral blades and a first drive motor; The conveying pipe is fixed to the extruder body, the hopper is fixed to the upper side of the conveying pipe, and the bottom outlet of the hopper is connected to the inlet of the conveying pipe. The rotating shaft is coaxially installed inside the conveying pipe, and the spiral blades are fixed to the outer wall of the rotating shaft; The first drive motor is fixed to the extruder body, and the output shaft of the first drive motor is coaxially connected to the rotating shaft.

[0017] As a preferred embodiment of the present invention, the spiral extrusion mechanism includes a spiral shaft, a transmission shaft, a universal joint, a gear, a planetary reducer, and a second drive motor; The two spiral shafts are coaxially installed inside the extrusion tube. The feed end of one of the spiral shafts is connected to the output shaft of the planetary reducer via a drive shaft and a universal joint. The input shaft of the planetary reducer is connected to the output shaft of the second drive motor. The feed end of the other screw shaft is rotatably connected to the extruder body via a drive shaft and a universal joint. Both drive shafts are equipped with gears, and the two gears mesh with each other.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. The graded dielectric constant insulation component is adopted. The dielectric constant of the three-layer structure decreases step by step along the direction of decreasing electric field strength, which can effectively homogenize the electric field distribution between high and low voltage windings, suppress extreme voltage impacts and local field strength concentration under long-term operation, and significantly reduce the risk of partial discharge. 2. The inner wall of the outer insulation cylinder is provided with axially continuous circumferential heat dissipation grooves, which greatly increases the heat dissipation contact area; heat-conducting strips with "S"-shaped through heat dissipation air channels are added inside the heat dissipation grooves to extend the heat exchange path of the cooling medium and enhance the heat exchange effect, which can efficiently dissipate the Joule heat generated by the winding operation. 3. The inner and outer insulating cylinders are made of nano-silica reinforced PA66 material, which has high rigidity and high resistance to deformation. The outer wall ribs of the inner insulating cylinder and the inner wall groove of the outer insulating cylinder are matched and engaged to ensure the coaxiality and overall rigidity of the insulation structure. It can effectively resist the electrodynamic impact under short-circuit conditions, avoid the misalignment and deformation failure of the insulation structure, and ensure the mechanical reliability of long-term operation.

[0019] Other additional advantages and benefits of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the isometric structure of the winding body in this invention; Figure 3 This is a partial cross-sectional view of the insulation structure in this invention; Figure 4 For the present invention Figure 3 Enlarged structural diagram at point A in the diagram; Figure 5 This is a schematic diagram of the cross-sectional structure of the heat-conducting strip in this invention; Figure 6 This is a schematic cross-sectional view of the gradient dielectric constant insulating component in this invention. Figure 7 This is a schematic diagram of the isometric structure of the extruder body in this invention; Figure 8 This is a schematic diagram of the cross-sectional structure of the die body in this invention; Figure 9 For the present invention Figure 8 Enlarged schematic diagram of the fixed mechanism in the diagram; Figure 10 This is a schematic diagram of the isometric structure of the molding core rod in this invention; Figure 11 This is a schematic cross-sectional view of the spiral conveying mechanism in this invention; Figure 12 This is a schematic diagram of the isometric structure of the spiral extrusion mechanism in this invention.

[0021] In the diagram: 1. Winding body; 11. High-voltage winding; 12. Low-voltage winding; 2. Outer insulating cylinder; 21. Heat dissipation groove; 22. Slot; 3. Inner insulating cylinder; 31. Rib; 4. Gradient dielectric constant insulating component; 41. Outer insulating coating; 42. Intermediate silicone rubber bushing; 43. Inner insulating coating; 5. Heat-conducting strip; 51. Heat dissipation duct; 6. Extruder body; 7. Extrusion tube; 8. Die body; 81. Flow guide seat; 811. Flow guide hole; 812. Positioning hole; 82. Flow equalization plate; 821. Flow guide cone; 822. Flow equalization hole; 823. Threaded hole; 83. Forming core rod; 831. Flow equalization section; 8311. Archimedean spiral 832. Forming section; 8321. First boss; 8322. Forming channel; 8323. Second boss; 833. Threaded rod; 84. Outer mold cylinder; 85. Fixing mechanism; 851. Positioning screw; 852. Nut; 86. Rubber sealing ring; 9. Hopper; 10. Screw conveying mechanism; 101. Conveying pipe; 102. Rotating shaft; 103. Spiral blade; 104. First drive motor; 13. Diverter box; 131. Diverter cone; 14. Screw extrusion mechanism; 141. Screw shaft; 142. Transmission shaft; 143. Universal joint; 144. Gear; 145. Planetary reducer; 146. Second drive motor. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0023] Please see Figures 1-6The present invention provides the following technical solution: a transformer high and low voltage winding insulation structure, applied to a 10kV dry-type power transformer, wherein the winding body 1 is a coaxially sleeved cylindrical winding, the high voltage winding 11 is located on the radial outer side, the low voltage winding 12 is located on the radial inner side, the transformer has a rated capacity of 1000kVA and a rated frequency of 50Hz.

[0024] The insulation structure provided by the present invention is disposed between the high-voltage winding 11 and the low-voltage winding 12 coaxially sleeved on the winding body 1. It includes an outer insulating cylinder 2, an inner insulating cylinder 3 and at least one set of gradient dielectric constant insulation components 4 coaxially and sequentially sleeved. The gradient dielectric constant insulation components 4 are disposed on the outer wall of the outer insulating cylinder 2 and / or the inner wall of the inner insulating cylinder 3. It should be noted that the insulation structure disclosed in this embodiment includes two sets of gradient dielectric constant insulation components 4, one set of which is disposed on the outer wall of the outer insulating cylinder 2 (towards the high-voltage winding 11), and the other set is disposed on the inner wall of the inner insulating cylinder 3 (towards the low-voltage winding 12).

[0025] Both the outer insulating cylinder 2 and the inner insulating cylinder 3 are reinforced PA66 insulating cylinders doped with nano-silica, and contain the following components by weight: PA66 resin: 94 parts by weight; surface hydroxylated modified nano silica: 5 parts by weight; antioxidant 1010: 0.3 parts by weight; lubricant calcium stearate: 0.7 parts by weight. The materials are mixed evenly and then granulated by twin-screw extrusion.

[0026] Furthermore, by Figures 1-4 As shown, the outer insulating cylinder 2 has an inner diameter of 220mm, a wall thickness of 8mm, and an axial length of 450mm (matching the axial length of the high-voltage winding 11). The inner wall is provided with 20 heat dissipation grooves 21 evenly distributed circumferentially. The heat dissipation grooves 21 are rectangular through grooves with a width of 6mm and a depth of 3mm, which pass through both ends of the outer insulating cylinder 2 axially. A retaining groove 22 is provided between two adjacent heat dissipation grooves 21. The retaining groove 22 is a rectangular groove with a width of 3mm and a depth of 1.5mm, which passes through axially. The 20 retaining grooves 22 and the 20 heat dissipation grooves 21 are evenly spaced circumferentially.

[0027] The inner insulating cylinder 3 has an outer diameter of 204mm, a wall thickness of 6mm, and an axial length of 450mm, the same as the outer insulating cylinder 2. Twenty axially extending ribs 31 are evenly arranged along the circumference of the outer wall. The ribs 31 are rectangular ribs with a width of 3.2mm, a height of 1.5mm, and an axial length consistent with the inner insulating cylinder 3. The ribs 31 correspond one-to-one with the slots 22 and are interlocked with an interference fit of 0.2mm, so as to achieve coaxial positioning and circumferential and radial limiting of the outer insulating cylinder 2 and the inner insulating cylinder 3.

[0028] As a preferred embodiment, by Figures 1-5As shown, each heat sink 21 is fitted with a heat-conducting strip 5 with an interference fit of 0.15 mm. The heat-conducting strip 5 is made of boron nitride-filled silicone rubber with a filling amount of 50 wt% and a thermal conductivity of 2.5 W / (m・K). Its shape is perfectly matched with the heat sink 21, ensuring a tight fit with the inner wall of the heat sink 21 and reducing contact thermal resistance.

[0029] An "S"-shaped heat dissipation air duct 51 is provided inside the heat conduction strip 5. The heat dissipation air duct 51 has a circular cross-section with a diameter of 2mm. It extends in a continuous "S"-shaped bend along the axial direction of the heat conduction strip 5, passing through both ends of the axial direction of the heat conduction strip 5. The S-shaped bend pitch is 50mm and the bend amplitude is 4mm. Cooling air (generated by a fan, which is a conventional component of dry-type transformers and will not be described in detail in this embodiment) can flow freely from both ends of the heat dissipation air duct 51, extending the heat exchange path and enhancing the convective heat exchange effect.

[0030] As a preferred embodiment, by Figures 1-3 , Figure 6 As shown, the gradient dielectric constant insulating component 4 includes an outer insulating coating 41, a middle silicone rubber bushing 42, and an inner insulating coating 43 arranged in sequence. The dielectric constant of the outer insulating coating 41, the middle silicone rubber bushing 42, and the inner insulating coating 43 decreases stepwise along the direction of decreasing electric field strength.

[0031] External insulating coating 41: Epoxy resin coating doped with barium titanate ceramic particles, with a coating thickness of 0.2 mm; by weight, it contains: 100 parts by weight of bisphenol A type epoxy resin E-51; 35 parts by weight of silane coupling agent KH550 modified nano barium titanate particles (particle size 50-100 nm); 85 parts by weight of curing agent methyltetrahydrophthalic anhydride; 0.8 parts by weight of accelerator DMP-30; and 0.3 parts by weight of defoamer; cured at room temperature for 24 h and then cured at 80℃ for 4 h, with a relative permittivity of 15-30 (relative permittivity of 22 at 1 kHz and 25℃).

[0032] Intermediate silicone rubber bushing 42: addition-cured methyl vinyl silicone rubber bushing, 0.8 mm thick, Shore A45 hardness, tear strength ≥15 kN / m; bonded between the outer insulating coating 41 and the inner insulating coating 43 by room temperature vulcanized silicone rubber, with a relative permittivity of 6-10 (relative permittivity of 8 at 1 kHz and 25 °C).

[0033] Inner insulating coating 43: Nano-silica modified polyimide coating, coating thickness 0.15mm; by weight, it contains: 100 parts by weight of homopolymer polyimide resin; 8 parts by weight of surface-modified nano-silica; 300 parts by weight of solvent N,N-dimethylacetamide; 0.5 parts by weight of leveling agent; cured by stepped temperature increase (80℃ / 1h→150℃ / 1h→220℃ / 2h), with a relative permittivity of 2-4 (the relative permittivity is 3.2 at 1kHz and 25℃).

[0034] The present invention employs a gradient dielectric constant insulation component 4. The dielectric constant of the three-layer structure decreases step by step along the direction of decreasing electric field strength, which can effectively homogenize the electric field distribution between high and low voltage windings, suppress extreme voltage impacts and local field strength concentration under long-term operation, and significantly reduce the risk of partial discharge.

[0035] The inner wall of the outer insulating cylinder 2 is provided with an axially through circumferential heat dissipation groove 21, which greatly increases the heat dissipation contact area; a heat-conducting strip 5 with an "S"-shaped through heat dissipation air duct 51 is installed in the heat dissipation groove 21 to extend the heat exchange path of the cooling medium and enhance the heat exchange effect, which can efficiently dissipate the Joule heat generated by the operation of the winding body 1. Both the outer insulating cylinder 2 and the inner insulating cylinder 3 are made of nano-silica reinforced PA66 material, which has high rigidity and high resistance to deformation. The outer wall rib 31 of the inner insulating cylinder 3 and the inner wall groove 22 of the outer insulating cylinder 2 are matched and engaged, which ensures the coaxiality and overall rigidity of the insulation structure. It can effectively resist the electrodynamic impact under short circuit conditions, avoid the misalignment and deformation failure of the insulation structure, and ensure the mechanical reliability of long-term operation. Example 2

[0036] A processing device for the high and low voltage winding insulation structure of a transformer is provided for processing the high and low voltage winding insulation structure of the transformer described in the above embodiment. It should be noted that, as an example, the processing device in this embodiment is used to process the outer insulation cylinder 2. When processing the inner insulation cylinder 3, only the corresponding die body 8 needs to be replaced. The two sets of die bodies 8 are the same except for the size, the outer wall shape of the forming core rod 83 and the inner wall shape of the outer die cylinder 84. This embodiment will not be described in detail.

[0037] Depend on Figures 7-12 As shown, the processing device for the high and low voltage winding insulation structure of the transformer includes an extruder body 6, an extrusion tube 7, a die body 8, a hopper 9, a screw conveying mechanism 10, a diverter box 13, and a screw extrusion mechanism 14. The extruder body 6 is a horizontal welded frame structure, which is formed by welding Q235 steel plate.

[0038] The screw conveying mechanism 10 includes a conveying pipe 101, a rotating shaft 102, screw blades 103, and a first drive motor 104. The conveying pipe 101 is a seamless steel pipe with an inner diameter of 80 mm, which is horizontally fixed to the upper part of the extruder body 6. The hopper 9 is a 50 L conical hopper, which is fixed to the upper side of the conveying pipe 101 by a flange. The discharge port at the bottom of the hopper 9 is coaxially connected to the feed port of the conveying pipe 101. The rotating shaft 102 is made of 40Cr tempered steel and is coaxially installed inside the conveying pipe 101. Both ends are rotatably supported by bearings with seats. The screw blades 103 have an equidistant and equal-depth structure with a pitch of 60 mm and an outer diameter of 78 mm. They are welded and fixed to the outer wall of the rotating shaft 102. The first drive motor 104 is a 7.5 kW variable frequency speed control motor, which is fixed to the extruder body 6 by bolts. The output shaft is coaxially connected to the rotating shaft 102 by a coupling. The conveying speed can be adjusted by frequency conversion to match the extrusion volume.

[0039] Principle: The first drive motor 104 drives the rotating shaft 102 to rotate through the coupling. The rotating shaft 102 drives the spiral blade 103 fixed on it to rotate coaxially. When the spiral blade 103 rotates, it pushes the material in the conveying pipe 101 to move by the pushing force of the blade.

[0040] The diversion box 13 is made of cast steel and has a conical diversion cavity inside. The feed inlet is sealed to the discharge port at the end of the conveying pipe 101 through a flange. A diversion cone 131 is fixed to the inner side of the discharge port at the bottom of the diversion box 13 by bolts. The diversion cone 131 has a conical cross section with the cone tip facing the feed inlet and a cone angle of 60°. It is used to uniformly guide the horizontally conveyed molten material into the extrusion pipe 7 below.

[0041] The extrusion tube 7 is a seamless 38CrMoAl nitrided steel pipe with an inner diameter of 220mm. It is horizontally installed on the top of the extruder body 6. One end is sealed and connected to the bottom discharge port of the diversion box 13 through a flange, and the other end is the discharge end. A heating device (a standard configuration for extruders) is installed on the outer wall of the extrusion tube 7 along the axial direction.

[0042] The screw extrusion mechanism 14 includes a screw shaft 141, a drive shaft 142, a universal joint 143, a gear 144, a planetary reducer 145, and a second drive motor 146. The two screw shafts 141 are intermeshing conical twin screws made of 38CrMoAl material and are coaxially installed inside the extrusion tube 7. The upper end of one screw shaft 141 is connected to the output shaft of the planetary reducer 145 via the drive shaft 142 and the universal joint 143. The planetary reducer 145 has a transmission ratio of 25:1, and its input shaft is coaxially connected to the second drive motor 146 (18.5kW variable frequency speed control motor). The upper end of the other screw shaft 141 is rotatably connected to the extruder body 6 via the drive shaft 142 and the universal joint 143. Both drive shafts 142 are fixed with gears 144 of the same module and number of teeth by flat keys. The two gears 144 mesh with each other to realize the synchronous and opposite rotation of the two screw shafts 141, ensuring stable material conveying and uniform plasticization.

[0043] Principle: The second drive motor 146 drives the active helical shaft 141 to rotate through the transmission shaft 142, universal joint 143 and planetary reducer 145, and at the same time drives the active gear 144 to rotate. Under the meshing action, the gear 144 drives the driven gear 144 to rotate. The driven gear 144 drives the other helical shaft 141 to rotate synchronously in opposite directions through the transmission shaft 142 and universal joint 143.

[0044] The die body 8 is coaxially and sealed to the discharge end of the extrusion tube 7 by means of a fixing mechanism 85. The die body 8 includes a guide seat 81, a flow equalization plate 82, a forming core rod 83 and an outer die cylinder 84 arranged coaxially in sequence. All parts are made of 40Cr tempered steel.

[0045] Among them, the flow guide seat 81 is a disc-shaped structure with a circular flow guide hole 811 in the center. One end of the flow guide hole 811 is coaxially connected to the inner hole of the extrusion tube 7, and the diameter of the hole is the same as the inner diameter of the extrusion tube 7.

[0046] The flow equalization plate 82 has a disc-shaped structure. A guide cone 821 is welded and fixed to the center of the feed side. The tip of the guide cone 821 faces the feed side and has a cone angle of 90°. It is used to evenly disperse the molten material flowing in from the center to the circumference. The flow equalization plate 82 has 20 flow equalization holes 822 evenly distributed along the circumference. The flow equalization holes 822 are φ8mm axial through holes to realize the circumferential uniform distribution of molten material and eliminate the difference in melt flow rate.

[0047] One end of the forming core rod 83 is coaxially and integrally fixed with a threaded rod 833. The center of the flow equalization plate 82 is provided with a matching threaded hole 823. The forming core rod 83 is coaxially fixed to the flow equalization plate 82 by threaded rotation, and can be quickly replaced according to the specifications of the insulating cylinder.

[0048] The forming core rod 83 includes a flow equalization section 831 and a forming section 832 that are coaxially and integrally connected. The outer wall of the flow equalization section 831 has 20 circumferentially evenly distributed Archimedes spiral flow channels 8311. The inlet end of the Archimedes spiral flow channel 8311 is connected to the flow equalization hole 822 of the flow equalization plate 82, and the outlet end is connected to the forming flow channel 8322 of the forming section 832. The depth of the Archimedes spiral flow channel 8311 increases gradually from the inlet end to the outlet end, with a channel depth of 2mm at the inlet end and 5mm at the outlet end. This achieves smooth deceleration and uniform distribution of the melt, eliminates internal stress, and avoids weld lines and deformation in the product.

[0049] The outer wall of the forming section 832 is provided with 20 circumferentially evenly distributed and axially extended first protrusions 8321 for forming the heat dissipation grooves 21 of the outer insulating cylinder 2. The first protrusions 8321 are 6mm wide and 3mm high. A forming flow groove 8322 is formed between two adjacent first protrusions 8321. A second protrusion 8323 is provided in the forming flow groove 8322 for forming the slots 22 of the outer insulating cylinder 2. The second protrusion 8323 is 3mm wide and 1.5mm high.

[0050] The outer mold cylinder 84 is a cylindrical structure, coaxially sleeved on the outer wall of the forming core rod 83, and fixedly connected to the flow equalization plate 82 by internal hexagonal bolts; an annular forming flow channel is formed between the inner wall of the outer mold cylinder 84 and the outer wall of the forming core rod 83, and the cross-sectional dimensions of the flow channel match the cross-sectional dimensions of the outer insulating cylinder 2, for integral extrusion forming of the outer insulating cylinder 2.

[0051] Depend on Figures 7-9 As shown, the fixing mechanism 85 includes positioning screws 851 and nuts 852: four positioning screws 851 are uniformly welded and fixed to the outer wall of the discharge end of the extrusion tube 7 along the circumference, with their axes parallel to the extrusion tube 7; the outer edge of the guide seat 81 is provided with four positioning holes 812 that correspond one-to-one with the positioning screws 851, the positioning screws 851 pass through the positioning holes 812, and the nuts 852 are screwed into the protruding end of the positioning screws 851 to press and fix the guide seat 81 to the discharge end of the extrusion tube 7.

[0052] The mating surfaces between the flow guide seat 81 and the extrusion tube 7, between the flow equalization plate 82 and the flow guide seat 81, and between the outer mold cylinder 84 and the flow equalization plate 82 are all provided with annular sealing grooves. A rubber sealing ring 86 made of fluororubber is embedded in the groove to ensure the sealing of the mating surfaces and prevent melt leakage.

[0053] The processing device in this embodiment has the following working process: Step 1: Place the PA66 raw material doped with nano-silica in a forced-air drying oven and dry it at 120℃ for 4 hours to remove the moisture from the raw material and avoid defects such as bubbles and silver streaks during the extrusion process; Step 2: Start the heating device of the extruder body 6 to preheat the extrusion tube 7 at 270℃ for 2 hours. The heat is simultaneously transferred to the distribution box 13 and the die body 8 to preheat both. Step 3: Start the first drive motor 104, adjust the speed to 10 rpm, add the dried raw material to the hopper 9, and the raw material is conveyed to the distribution box 13 through the screw conveyor mechanism 10; at the same time, start the second drive motor 146, adjust the speed to 15 rpm, drive the double screw shaft 141 to rotate synchronously in opposite directions, plasticize the molten material and convey it to the die body 8. Step 4: The molten material enters the die through the guide hole 811, is circumferentially dispersed by the guide cone 821, and is evenly distributed through the flow equalization hole 822. It then enters the Archimedes spiral flow channel 8311 to further equalize the pressure and flow rate, and finally enters the forming flow channel to integrally extrude and form the outer insulating cylinder 2 blank with heat dissipation groove 21 and card slot 22.

[0054] Step 5: After subsequent sizing, traction, and cooling, the extruded preform is cut to the set length to obtain the outer insulating cylinder 2 finished product; the inner insulating cylinder 3 can be extruded and formed using the same process by replacing the corresponding specification forming core rod 83 and outer mold cylinder 84. Example 3

[0055] This embodiment is an adaptation solution for small-capacity power transformers, and its difference from Embodiment 1 is as follows: Only one set of gradient dielectric constant insulation component 4 is provided, located only on the outer wall of the outer insulation cylinder 2 (on the high voltage winding 11 side). It is suitable for dry-type transformers with voltage less than 10kV, capacity less than 315kVA, and low field strength on the low voltage winding 12 side, which simplifies the structure and reduces manufacturing costs.

[0056] Simultaneously adjust the gradient dielectric parameters: the outer insulating coating 41 has a relative dielectric constant of 18, the middle silicone rubber bushing 42 has a relative dielectric constant of 7, and the inner insulating coating 43 has a relative dielectric constant of 2.8, maintaining the core design of a gradient decrease in dielectric constant along the electric field direction.

[0057] The remaining structure, material formulation, and dimensional parameters are completely consistent with those of Example 1.

[0058] In this invention, the gradient dielectric constant insulation component 4 adopts a three-layer structure in which the dielectric constant decreases stepwise along the direction of decreasing electric field strength. According to electrostatic field theory, when multiple dielectric layers are connected in series, the electric field strength of each dielectric layer is inversely proportional to the dielectric constant. By setting a high dielectric constant coating (outer insulating coating 41) on the high-voltage side with high field strength and a low dielectric constant coating (inner insulating coating 43) on the low-voltage side with low field strength, the radial electric field distribution can be effectively balanced, the maximum field strength on the high-voltage side can be reduced, local field strength concentration can be suppressed, partial discharge can be avoided, and the breakdown voltage and long-term operational reliability of the insulation structure can be significantly improved.

[0059] The axial heat dissipation grooves 21 on the inner wall of the outer insulating cylinder 2 significantly increase the contact area between the insulating cylinder and the cooling medium; the heat conduction strip 5 quickly dissipates the heat of the insulating cylinder, and its internal "S"-shaped heat dissipation air duct 51 extends the heat exchange path and heat exchange time of the cooling medium, improves heat exchange efficiency, can efficiently dissipate the Joule heat generated by the winding operation, reduce the operating temperature of the insulation structure, delay thermal aging, and extend service life.

[0060] The insulating cylinder is made of nano-silica reinforced PA66 material, which has high rigidity and resistance to deformation. The interlocking structure of the rib 31 and the slot 22 realizes the coaxial positioning and multi-directional limiting of the two cylinders, forming an overall rigid support structure, which can effectively resist the radial electrodynamic impact under short circuit conditions, avoid misalignment, deformation and cracking failure of the insulation structure, and improve the short circuit withstand capability of the transformer.

[0061] The processing device of the present invention adopts a twin-screw extrusion and a special die integrated molding process. The spiral feeding mechanism 10 realizes stable material transportation, the diversion box 13 and the diversion cone 131 realize stable material flow guidance, and the twin-screw extrusion mechanism 14 realizes uniform plasticization and stable extrusion of the material. The special die body 8 realizes uniform circumferential flow of the melt through the guide cone 821 and the flow equalization plate 82. The Archimedes spiral flow channel 8311 of the forming core rod 83 further equalizes the melt pressure and flow rate and eliminates internal stress. Finally, the outer insulating cylinder 2 blank with heat dissipation groove 21 and slot 22 is integrally extruded through the forming flow channel.

[0062] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A transformer high-voltage and low-voltage winding insulation structure, disposed between a high-voltage winding (11) and a low-voltage winding (12) coaxially sleeved on the winding body (1), characterized in that: It includes an outer insulating cylinder (2) and an inner insulating cylinder (3) coaxially and sequentially nested together, and at least one set of gradient dielectric constant insulating components (4), wherein the gradient dielectric constant insulating components (4) are disposed on the outer wall of the outer insulating cylinder (2) and / or the inner wall of the inner insulating cylinder (3); The inner wall of the outer insulating cylinder (2) is provided with a plurality of heat dissipation grooves (21) evenly distributed along the circumference, and the heat dissipation grooves (21) penetrate through both ends of the outer insulating cylinder (2). The gradient dielectric constant insulation component (4) includes an outer insulating coating (41), an intermediate silicone rubber bushing (42), and an inner insulating coating (43) arranged in sequence. The dielectric constants of the outer insulating coating (41), the intermediate silicone rubber bushing (42), and the inner insulating coating (43) decrease gradually along the direction of decreasing electric field strength.

2. The transformer high and low voltage winding insulation structure according to claim 1, characterized in that: The outer wall of the inner insulating cylinder (3) is uniformly provided with multiple axially extending ribs (31) along the circumference, and the inner wall of the outer insulating cylinder (2) is provided with multiple slots (22) that are adapted to the ribs (31).

3. The transformer high and low voltage winding insulation structure according to claim 1, characterized in that: The heat dissipation groove (21) is provided with a heat-conducting strip (5), and an "S"-shaped heat dissipation air duct (51) is opened in the heat-conducting strip (5), and the heat dissipation air duct (51) passes through both ends of the heat-conducting strip (5).

4. The transformer high and low voltage winding insulation structure according to claim 1, characterized in that: The outer insulating coating (41) is an epoxy resin doped with barium titanate ceramic particles, with a relative permittivity of 15-30; the intermediate silicone rubber bushing (42) is an addition-type methyl vinyl silicone rubber, with a relative permittivity of 6-10; and the inner insulating coating (43) is a nano-silica modified polyimide, with a relative permittivity of 2-4.

5. The transformer high and low voltage winding insulation structure according to claim 1, characterized in that: Both the outer insulating cylinder (2) and the inner insulating cylinder (3) are reinforced PA66 insulating cylinders doped with nano-silica.

6. A processing apparatus for the high-voltage and low-voltage winding insulation structure of a transformer, used for processing the high-voltage and low-voltage winding insulation structure of the transformer as described in any one of claims 1-5, characterized in that: It includes an extruder body (6), an extrusion tube (7), a die body (8), a hopper (9), a screw conveying mechanism (10), a diverter box (13), and a screw extrusion mechanism (14). The extrusion tube (7) is disposed on the top of the extruder body (6); The die body (8) is coaxially and sealed to the discharge end of the extrusion tube (7) by means of a fixing mechanism (85). The die body (8) includes a flow guide seat (81), a flow equalization plate (82), a forming core rod (83), and an outer die cylinder (84) arranged coaxially in sequence. A flow guide hole (811) is provided at the center of the flow guide seat (81), and a flow guide cone (821) is fixed on the side of the flow equalization plate (82) facing the flow guide hole (811). A plurality of flow equalization holes (822) are provided on the flow equalization plate (82) evenly distributed in the circumferential direction, which are used to evenly divide the molten material in the circumferential direction. One end of the forming core rod (83) is fixed with a threaded rod (833), and the flow equalization plate (82) is provided with a threaded hole (823) that matches the threaded rod (833). The outer wall of the forming core rod (83) is provided with a first boss (8321) for forming a heat dissipation groove (21), and a forming flow groove (8322) is formed between two adjacent first bosses (8321). A second boss (8323) for forming a slot (22) is provided in the forming flow groove (8322). The outer mold cylinder (84) is coaxially sleeved on the outer wall of the forming core rod (83) and fixedly connected to the flow equalization plate (82). A forming flow channel for forming the outer insulating cylinder (2) is formed between the outer mold cylinder (84) and the forming core rod (83). The hopper (9) is fixed to the top of the extruder body (6), and the feed port of the screw conveyor (10) is connected to the discharge port at the bottom of the hopper (9); The feed inlet of the diversion box (13) is connected to the end outlet of the screw conveyor (10). A diversion cone (131) with a conical cross section is fixed inside the bottom outlet of the diversion box (13), and the bottom outlet of the diversion box (13) is connected to the feed inlet of the extrusion tube (7). The spiral extrusion mechanism (14) is coaxially connected to the end of the extrusion tube (7) away from the die body (8).

7. The processing apparatus for the high and low voltage winding insulation structure of a transformer according to claim 6, characterized in that: The fixing mechanism (85) includes a positioning screw (851) and a nut (852); Multiple positioning screws (851) are uniformly fixed circumferentially to the outer wall of the discharge end of the extrusion tube (7); The guide seat (81) has a positioning hole (812) for the positioning screw (851) to pass through, and the nut (852) is provided on the extended end of the positioning screw (851) by means of thread engagement; Rubber sealing rings (86) are provided between the flow guide seat (81) and the extrusion tube (7), between the flow equalization plate (82) and the flow guide seat (81), and between the outer mold cylinder (84) and the flow equalization plate (82).

8. The processing apparatus for the high and low voltage winding insulation structure of a transformer according to claim 6, characterized in that: The forming core rod (83) includes a flow equalization section (831) and a forming section (832) that are coaxially and integrally connected. The outer wall of the flow equalization section (831) is provided with a number of Archimedes spiral flow channels (8311) evenly distributed in the circumference. The inlet end of the Archimedes spiral flow channel (8311) is connected to the outlet side of the flow equalization plate (82), and the outlet end is connected to the forming flow channel (8322). The depth of the Archimedes spiral flow channel (8311) increases step by step from the inlet end to the outlet end. The first boss (8321) and the second boss (8323) are disposed on the outer wall of the forming section (832).

9. The processing apparatus for the insulation structure of transformer high and low voltage windings according to claim 6, characterized in that: The spiral conveying mechanism (10) includes a conveying pipe (101), a rotating shaft (102), spiral blades (103) and a first drive motor (104). The conveying pipe (101) is fixed on the extruder body (6), the hopper (9) is fixed on the upper side of the conveying pipe (101), and the bottom outlet of the hopper (9) is connected to the inlet of the conveying pipe (101). The rotating shaft (102) is coaxially installed inside the conveying pipe (101), and the spiral blade (103) is fixed to the outer wall of the rotating shaft (102); The first drive motor (104) is fixed on the extruder body (6), and the output shaft of the first drive motor (104) is coaxially connected to the rotating shaft (102).

10. The processing apparatus for the high and low voltage winding insulation structure of a transformer according to claim 6, characterized in that: The spiral extrusion mechanism (14) includes a spiral shaft (141), a transmission shaft (142), a universal joint (143), a gear (144), a planetary reducer (145), and a second drive motor (146). Two spiral shafts (141) are coaxially installed inside the extrusion tube (7). The feed end of one of the spiral shafts (141) is connected to the output shaft of the planetary reducer (145) via a drive shaft (142) and a universal joint (143). The input shaft of the planetary reducer (145) is connected to the output shaft of the second drive motor (146). The feed end of the other spiral shaft (141) is rotatably connected to the extruder body (6) via a drive shaft (142) and a universal joint (143). Both drive shafts (142) are equipped with gears (144), and the two gears (144) mesh with each other.

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