Anti-cracking and anti-explosion combined insulation core
By adopting a combination of pultruded tubes and circumferential fiberglass winding rings as the insulating core, the problems of waste and high cost in the production of hollow composite insulators have been solved, achieving efficient and low-cost manufacturing of high-performance insulators, and significantly improving product quality and performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN CHUZHENG HIGH VOLTAGE INSULATION CO LTD
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-19
AI Technical Summary
The existing hollow composite insulator production process suffers from environmental pollution from waste, low production efficiency, and high costs. Furthermore, existing improvement processes are complex and costly.
The crack-resistant and explosion-proof composite insulation core consists of a pultruded tube and a circumferential fiberglass winding ring. By pushing the pre-made winding ring onto the pultruded tube, the circumferential fiber is used to increase the bending strength and internal pressure resistance. Combined with a silicone rubber sheath, a sliding tight fit is formed, avoiding weak points and simplifying the production process.
It achieves virtually zero-waste production, saves raw materials, electricity and labor costs, reduces costs by 50%, and produces products with superior quality to spiral wound pipes, significantly improved resistance to internal pressure and bending strength, and meets national standards.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of high-voltage substation equipment, and more specifically to a composite insulating core used in the manufacture of hollow composite insulators. Background Technology
[0002] Currently, hollow composite insulators used in high-voltage, ultra-high-voltage, and extra-high-voltage transformers, circuit breakers, capacitors, and other equipment in substations both domestically and internationally are all made of epoxy resin-coated fiberglass spiral wound tubes (commonly known as fiberglass pipes, hereinafter referred to as spiral wound tubes). The production of spiral wound tubes is inefficient, consumes a lot of electricity, is costly, and wasteful. In particular, the waste material from the sawn-off ends and the waste material from the machined outer surface of the semi-finished middle section exceeds 30% of the product weight, and this waste is difficult to recycle. Because crushing this waste is very costly—for example, grinding it into powder costs more than the material itself—very few manufacturers deeply process and utilize the spiral wound tube waste. This problem has long plagued spiral wound tube manufacturers. Some manufacturers have attempted to reduce or eliminate waste by machining grooves on the outside of pultruded tubes, then filling the grooves with fiberglass yarn wet-impregnated with epoxy resin, followed by a second curing process (see patent application number: 201921331271.X), in order to improve the mechanical strength and internal pressure resistance of the pultruded tubes. This patented product has three defects: 1. Grooving the pultruded tube with the same 10mm wall thickness as the original wound tube damages the tube wall and reduces its bending strength. The groove depth is limited by the wall thickness, resulting in limited strength of the circumferential fiberglass winding layer. Increasing the wall thickness to create circumferential grooves requires lathe machining, increasing costs. 2. The pultruded tube wall thickness between the two grooves is relatively large, but the portion above the bottom of the groove is not reinforced by the circumferential epoxy fiberglass winding within the groove. 3. Due to the limited wall thickness of the pultruded tube, achieving the set clamping force for the circumferential winding layer inevitably requires increasing the pultruded tube wall thickness, increasing product costs. 4. After machining the grooves on a lathe, the pultruded tube is then filled with circumferential fiberglass resin and subsequently cured in an oven. This process is complex, time-consuming, labor-intensive, inefficient, and costly. Summary of the Invention
[0003] This invention addresses the environmental pollution caused by the large amount of waste generated during the production of spiral wound tubing. The complex processes of pultruded tubing, grooved winding, epoxy resin, glass fiber filling, and secondary curing significantly increase product costs. Adhering to the principle that the best waste utilization is to generate no waste, this patent provides a crack-resistant and explosion-proof combined insulating core (hereinafter referred to as the combined core) for manufacturing hollow composite insulators. The greatest advantage of this invention is that it generates virtually no waste during product manufacturing. Compared to spiral wound tubing, this patent saves 30% on raw materials, 20% on electricity costs, and 20% on labor, reducing costs by 50%. For products of the same diameter and wall thickness, the quality of this patented combined core is superior to that of spiral wound tubing: its internal pressure resistance is 1.3 times that of spiral wound tubing, its bending strength is 1.7 times that of spiral wound tubing, and its bending deformation is half that of spiral wound tubing. This product has good electrical performance, high mechanical strength, strong internal pressure resistance, and reliable quality, fully complying with the People's Republic of China National Standard GB / T44179--2024, and is a replacement product for traditional spiral wound insulating tubing.
[0004] Compared with the background patent 201921331271.X (hereinafter referred to as the background patent), this invention differs in three essential aspects: 1. The background patent's pultruded tube (referred to as the pultruded tube in this patent) involves slotting the original 10mm wall thickness, which reduces the product's bending strength and does not increase its internal pressure resistance. Furthermore, the slotting depth is limited by the wall thickness; increasing the wall thickness for slotting would result in a different size from the original sleeve, making it difficult to match with other products and increasing costs. On the other hand, increasing the wall thickness can increase bending strength and internal pressure resistance, with better results than slotting, winding, and impregnating epoxy fiberglass, and the process is simpler. Therefore, thickening the tube wall and then slotting and winding epoxy fiberglass is not feasible, and this patent has no practical value. This patent increases the bending strength and internal pressure resistance of pultruded tubes by adding a circumferential glass fiber wound ring (hereinafter referred to as the wound ring). The diameter D and width h of the wound ring are not limited, and the bending strength and internal pressure resistance can be increased to a sufficiently safe level with a large margin. Because the wound ring is embedded in the silicone rubber sheath and the root of the umbrella skirt, increasing the volume of the wound ring reduces the volume of the silicone rubber by the same amount, with almost no increase in cost. The diameter of the pultruded tube is the same as the original wound tube, making it fully compatible with other products. 2. The background patent involves winding epoxy resin-impregnated glass fiber in a groove and then curing it twice. This process is complex, labor-intensive, time-consuming, and energy-intensive, resulting in low production efficiency and high cost. This patent uses a hydraulic cylinder to push the pre-made wound ring from the end of the pultruded tube, which is simple, efficient, and low-cost. 3. The background technology involves slotting the drawn tube, which is basically impossible to implement because the drawn tube has a curvature of 1.5-3 per thousand, and the grooves machined on the lathe are of varying depths, making it impossible to manufacture a finished product. This patent uses a hydraulic cylinder to push the wound ring from the end of the pultruded tube, which is simple, efficient, and low-cost.
[0005] This invention consists of a pultruded tube 1 and a circumferential fiberglass winding ring 2. All the fiberglass in the pultruded tube 1 is axial, while all the fiberglass in the winding ring 2 is circumferential. The fiberglass directions of the two components form a 90-degree right angle, maximizing the advantages of each component: the axially fiber pultruded tube 1 has high tensile strength but poor resistance to internal pressure, while the circumferential fiber winding ring 2 tightens the pultruded tube, increasing its resistance to internal pressure. The inner diameter of the winding ring 2 and the outer diameter of the pultruded tube 1 are in a sliding tight fit. The cross-sectional dimensions of the winding ring depend on the specified gas pressure inside the pultruded tube; the national standard specifies a maximum pressure of 40 MPa for hollow composite insulators. Based on the stress calculation formulas for pressure vessels, cantilever beams, and bending moments, it can be calculated that point A-1 / 2 of the tube length L is most prone to cracking when the internal pressure inside the pultruded tube is increased. Our experiments have confirmed this calculation result. Pultruded tubes of different lengths are fitted with flanges at both ends, and the flanges tighten the pultruded tube, which is equivalent to having two winding rings installed at points A-1 and A-2. Let the distance between the two flange ports be L. Take H values of 20mm, 40mm, 80mm, 160mm, 320mm, 640mm, 1280mm, and 2560mm respectively. During the test, the water pressure inside the pultruded tube was gradually increased to 4MPa. At H values of 20mm, 40mm, 80mm, 160mm, 320mm, and 640mm, the pultruded tube did not burst at a water pressure of 4MPa. When H was 1280mm, the pultruded tube burst at a water pressure of 3.1MPa, and at H was 2560mm, the pultruded tube burst at a water pressure of 2MPa. After installing clamps with a spacing of 320mm, it was placed under an internal pressure of 4.8MPa for 7 days without damage. Both theoretical calculations and actual tests prove that the bending moment force at the midpoint A-1 / 2 of the pultruded tube L is the largest, making it most prone to bursting. By adding a circumferential fiber winding ring 2 at the weak point A-1 / 2, the weak point of the pultruded tube is shifted to points A-1 / 4 and A-3 / 4. If the pultruded tube still cracks, winding rings are added at A-1 / 4 and A-3 / 4, shifting the weak point of the pultruded tube to four points: A-1 / 8, A-3 / 8, A-5 / 8, and A-7 / 8, and so on, until the pultruded tube 1 does not crack when the weak point withstands the specified water pressure. The spacing h and cross-section of the winding ring 2 can be determined based on the above test values. The fabrication and installation method of the winding ring 2 are detailed in Examples 1 and 2 below. Since the winding ring is at a floating potential, the charged parts in the equipment will not generate a discharge voltage sufficient to break down the pultruded tube wall on the clamp; therefore, the winding ring 2 can be made of metal. Attached Figure Description
[0006] Figure 1 A schematic diagram of the structure of this invention. Figure 2 Schematic diagram of a circumferential fiber winding ring. Figure 3 Schematic diagram of a cross-section of a hollow composite insulator made with a composite core. Detailed Implementation
[0007] Example 1: In this example, the winding process is carried out on a steel pipe mold. The distance between the two rings is h = 80 mm, and the cross-section of the winding ring is a × b = 10 mm × 10 mm. The pultruded tube 1 has a diameter of 280 mm, a length of 1300 mm, and a wall thickness of 10 mm. The specific implementation steps are as follows: 1. Use a winding machine to make a circumferential fiber winding ring 2 with an inner diameter of 280 mm and an outer diameter of 300 mm. 2. Cut the pultruded tube to a length of 2400mm, slightly chamfer the outer diameter of both ends with a hand grinder, and place it on a specially designed mounting bracket. 3. Place the winding ring 2 in a 100-degree Celsius oven for 4 hours. From the end of the pultrusion tube, use a hydraulic cylinder to push the winding ring 2 to a position 90mm away from the end. 4. Referring to step 3 above, place the second winding ring into the end. The first and second winding rings are supported by six 80mm support rods that are flexibly connected together. The spacing between the six support rods is 1 / 6 of the circumference of the pultruded tube. Place the heated winding ring into the end of the pultruded tube and use a hydraulic cylinder to push the second winding ring to a position 90mm from the end. Continue in this manner until the entire pultruded tube 1 is filled with winding rings 2 spaced at 80mm intervals, forming a crack-resistant and explosion-proof combined insulating core. 5. After inserting the steel liner into the composite core, place it into the silicone rubber mold to vulcanize the silicone rubber umbrella skirt 3, thus becoming a semi-finished product. 6. Install flanges at both ends of the semi-finished product to complete the entire process and produce a crack-resistant and explosion-proof hollow composite insulator. Example 2: 1. Place the 1340mm long pultruded tube 1 on a rotatable frame similar to a lathe. The frame is equipped with 11 non-woven fiberglass tape positioners that match the 80mm spacing of the winding rings 2. Install the winding rings 2 at 180mm from each end of the pultruded tube. 2. Rotate the pultrusion tube 2, and 11 non-woven fiberglass tapes are simultaneously wound layer by layer at 11 positions set on the pultrusion tube until the winding layer reaches the set thickness of the winding ring 2. 3. Place the pultruded tube 2 with non-woven fiberglass wrapping tape into an oven and heat it to 150 degrees Celsius for 4 hours to cure, thus producing a crack-resistant and explosion-proof combined insulating core. 4. Referring to 4 and 5 in Example 1 above, a crack-resistant and explosion-proof hollow composite insulator is made.
Claims
1. A crack-resistant and explosion-proof combined insulating core, characterized in that... It consists of a pultruded tube 1 and a circumferential glass fiber wound ring 2, with the axial fibers of the pultruded tube 1 and the circumferential fibers of the wound ring 2 forming a 90-degree right angle.
2. The crack-resistant, crack-resistant, and explosion-proof combined insulating core according to claim 1, characterized in that... Before the spiral wound ring 2 is inserted into the pultruded tube 1, it needs to be heated to 70 to 120 degrees Celsius to make the two fit together tightly by utilizing the principle of thermal expansion and contraction.
3. The crack-resistant and explosion-proof combined insulating core according to claim 1, characterized in that... The glass fibers of the pultruded tube 1 are all axial, while the glass fibers of the wound ring 2 are all circumferential.
4. The crack-resistant and explosion-proof combined insulating core according to claim 1, characterized in that... The winding ring 2 is made of glass fiber with epoxy resin that can withstand temperatures above 155 degrees Celsius. After being wound in a steel pipe mold, it is heated, cured, and cut into a pre-formed shape. It is then pushed to the set position from the end of the pultruded tube by a hydraulic cylinder.
5. The crack-resistant and explosion-proof combined insulating core according to claim 1 is characterized in that the winding ring is wrapped with non-woven glass ribbon at a set position outside the pultruded tube and then placed in an oven for high-temperature curing.
6. The crack-resistant and explosion-proof combined insulating core according to claim 1, characterized in that... The winding ring 2 is made of metal.
7. The crack-resistant and explosion-proof combined insulating core according to claim 1, characterized in that... The winding ring 2 is placed at the base of the silicone rubber umbrella skirt and is covered with silicone rubber to prevent it from being exposed to the atmosphere.