Lightweight rod insulator resistant to fatigue and pollution flashover and preparation method thereof

Abstract

This invention discloses a lightweight rod-shaped insulator with fatigue resistance and flashover resistance, and its preparation method, in the field of insulator manufacturing technology. The lightweight rod-shaped insulator includes a composite core rod, a sheath skirt covering the outer periphery of the composite core rod, and fittings pressed to both ends of the composite core rod. The composite core rod is composed of an epoxy resin-based composite material inner core and an outer reinforcing layer woven from basalt fiber-glass fiber strands. The sheath skirt is designed with a modified silicone rubber material formula containing C16-C22 alkyl-grafted polydimethylsiloxane, ternary modified reinforcing filler, and compounded anti-aging agent. This invention has excellent mechanical strength, flashover resistance, overvoltage resistance, and resistance to extreme environments, with significant lightweight effect. It can meet the speed-up requirements of electrified high-speed rail operation at speeds of 450 km / h and above, effectively ensure the safe and stable operation of the contact network, reduce operation and maintenance costs, and has good industrialization and promotion value.

Description

Technical Field

[0001] This invention relates to the field of insulator manufacturing technology, specifically to a lightweight rod-shaped insulator with fatigue resistance and flashover resistance and its preparation method. Background Technology

[0002] Rod insulators are an indispensable core insulation and support component of the electrified high-speed railway catenary system. They mainly play a crucial role in fixing the catenary conductors, isolating live conductors from grounding components, and transmitting mechanical loads. Their performance directly determines the insulation reliability and mechanical stability of the catenary system, which in turn affects the operating speed, safety level, and maintenance costs of electrified high-speed railways. As the speed of high-speed railways gradually increases to 450 km / h or even higher, the operating conditions faced by the catenary system are becoming increasingly stringent, placing higher and more demanding requirements on the performance of rod insulators.

[0003] The rod-shaped insulators used in the overhead contact system of electrified high-speed railways are mainly porcelain insulators and composite insulators. Compared with porcelain insulators, which are heavy and require high labor intensity during installation and replacement, and have high wind resistance at high speeds, which can easily increase the mechanical load on the contact network, composite insulators have a better application prospect. However, in actual application, composite insulators are prone to the following technical defects, which can lead to failure to meet the core requirements of high-speed operation: (1) Insufficient mechanical performance and weak impact and fatigue resistance: The bonding reliability between the core rod and the sheath of the composite insulator is insufficient. Under long-term alternating stress, the interface is prone to peeling and stress corrosion cracking of the core rod, which can lead to mechanical failure of the insulator; (2) Poor electrical insulation performance adaptability and insufficient resistance to flashover and overvoltage: The environmental adaptability of composite insulators is insufficient. Under strong ultraviolet and drastic temperature difference environments, the silicone rubber sheds are prone to powdering and cracking, resulting in loss of hydrophobicity and a significant drop in flashover voltage. In addition, the lightning impulse withstand voltage and power frequency dry and wet withstand voltage of composite insulators are difficult to meet the insulation requirements after speed increase, which can easily cause flashover tripping and affect the continuity of high-speed rail operation.

[0004] Therefore, in response to the technical problems of insufficient mechanical properties and poor electrical insulation adaptability of existing rod insulators during the speed increase of electrified high-speed railways, the development of a lightweight rod insulator that is resistant to fatigue and flashover is crucial to ensuring the safe speed increase of electrified high-speed railways and reducing operation and maintenance costs. This is also a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a lightweight rod-shaped insulator that is fatigue-resistant and pollution-resistant, and a method for its preparation, so as to solve the technical problems mentioned in the background art.

[0006] The present invention achieves the above objectives through the following technical solutions: In a first aspect, the present invention provides a lightweight rod-shaped insulator that is fatigue-resistant and pollution-resistant, comprising a composite core rod, a sheath skirt covering the outer periphery of the composite core rod, and fittings pressed to both ends of the composite core rod, wherein the composite core rod is composed of an epoxy resin-based composite material inner core and an outer reinforcing layer woven from basalt fiber-glass fiber strands. The sheath and skirt are integrally injection molded from modified silicone rubber. The raw materials include, by weight, 100 parts of methyl vinyl silicone rubber, 25-35 parts of hydrogenated nitrile rubber, 15-25 parts of C16-C22 alkyl-grafted polydimethylsiloxane, 46-66 parts of modified reinforcing filler, 1-2 parts of zinc stearate, 2-4 parts of hydroxyl silicone oil, 1-3 parts of anti-aging agent, 0.6-1.2 parts of bis(2,5) vulcanizing agent, and 0.2-0.3 parts of CTP anti-scorching agent.

[0007] As a further optimization of the present invention, the raw materials of the epoxy resin-based composite material core include, by weight, 55-65 parts epoxy resin, 18-25 parts curing agent, 8-15 parts nano-reinforcing components, 0.5-1 parts silane coupling agent, 0.3-0.6 parts organosilicon defoamer, and 0.2-0.4 parts internal release agent. The nano-reinforcing component is a mixture of nano-alumina and nano-silica in a mass ratio of 1-3:1-2.

[0008] As a further optimization of the present invention, in the basalt fiber-glass fiber ply yarn, the mass ratio of basalt fiber to glass fiber is 1-3:2, and the specification of the ply yarn is 300-500 tex; The outer reinforcing layer has a weave density of 18-26 threads / cm, and the weave structure is plain or twill.

[0009] As a further optimization of the present invention, the modified reinforcing filler comprises, by weight, 30-40 parts of fumed silica, 12-18 parts of wet-process modified fiber magnesia, and 4-8 parts of needle-shaped nano zinc oxide.

[0010] As a further optimization of the present invention, the anti-aging agent is a mixture of benzotriazole and hindered phenolic antioxidants at a mass ratio of 1-2:1.

[0011] A second aspect of the present invention provides a method for preparing a lightweight rod-shaped insulator with fatigue resistance and flashover resistance as described in any one of the above claims, comprising the following steps: (1) Preparation of inner core: According to the formula, the nano-reinforcing component and silane coupling agent are stirred at high speed, ultrasonically dispersed and dried, mixed with preheated epoxy resin and curing agent, vacuum degassed, pre-pressed, high temperature and high pressure cured, demolded and heat-preserved to obtain the inner core; (2) Preparation of composite core rod: The outer reinforcing layer woven from basalt fiber-glass fiber strands is subjected to plasma treatment, impregnated with epoxy impregnation adhesive and pre-dried to semi-dry, and then wrapped around the inner core in a circumferential direction. After curing by heating and pressurizing and cooling to demold, an integrated composite core rod is obtained. (3) Preparation of sheath skirt: Methyl vinyl silicone rubber and hydrogenated nitrile rubber are mixed in an intensive manner, and modified reinforcing fillers and additives are added and mixed. After granulation, a special mold and injection molding machine are used to inject and vulcanize the mixture under set temperature and pressure to obtain an integrated insulator semi-finished product. (3) Fitting assembly: Press the fittings onto both ends of the composite core rod, and install the equalizing ring and sealing sleeve to complete the finished product assembly and obtain the lightweight rod-shaped insulator.

[0012] As a further optimization of the present invention, in step (1), the process parameters for the molding of the inner core are as follows: the pre-pressure is 2-4 MPa, the pressure is held for 5-8 min, after the air bubbles are removed, the core is cured at 150-160℃ and 10-12 MPa for 1-1.5 h under constant temperature and pressure, then slowly cooled to 50-60℃ for demolding, and then kept at 110-120℃ for 1-1.2 h to release internal stress.

[0013] As a further optimization of the present invention, the specific steps of step (2) are as follows: after plasma treatment of the outer reinforcing layer, epoxy impregnation adhesive is impregnated, the adhesive content is controlled to be 25±5%, and the inner core is pre-dried at 80-100℃ to a semi-dry state. Then, the inner core is tightly wrapped in a circumferential direction to ensure no wrinkles or gaps. The mold is closed and locked, and the temperature is increased to 140-150℃ at a gradient of 2-4℃ / min. The pressure is increased to 6-8MPa and held for 30-60min. The pressure is released at a uniform speed and the temperature is reduced to room temperature at a gradient of 2-3℃ / min before demolding to form a composite core rod with an integrated structure.

[0014] As a further optimization of the present invention, in step (2), the core process parameters of plasma treatment are: radio frequency of 13.56MHz, radio power of 100-150W, processing time of 60-90s, vacuum degree of 20-50Pa, working gas of O2 / Ar (3:1) and gas flow rate of 15-25sccm.

[0015] As a further optimization of the present invention, in step (3), the injection pressure of injection molding is set to 8-10MPa, the injection speed to 50-55mm / s, the holding pressure to 6-8MPa, and the holding time to 45-60s; the vulcanization temperature is 163±2℃, and the holding vulcanization time is 600±50s.

[0016] The beneficial effects of this invention are as follows: (1) The mandrel of the present invention adopts a composite structure of an epoxy resin-based composite inner core and an outer reinforcing layer woven from basalt fiber-glass fiber strands, which greatly improves the mechanical strength, impact resistance and fatigue resistance of the mandrel; (2) The present invention adopts a modified silicone rubber material formula containing C16-C22 alkyl-grafted polydimethylsiloxane, ternary modified reinforcing filler and compound anti-aging agent, so that the insulator can still stably meet the HC1 level hydrophobicity requirements after corona aging; effectively inhibits surface aging, powdering and hydrophobicity decay caused by corona discharge, and extends the service life of the insulator; in addition, the electrical insulation performance and pollution flashover resistance of the insulator are significantly improved, with lightning impulse withstand voltage >600kV, power frequency wet withstand voltage >200kV, and artificial pollution power frequency flashover voltage >130kV, which can withstand the operating overvoltage and lightning overvoltage of the contact network system after the high-speed rail speed-up, ensuring the insulation safety of the contact network system; finally, the insulator has strong environmental adaptability and a wide applicable temperature range; The rod-shaped insulator proposed in this invention can meet the speed-up requirements of electrified high-speed rail operation at speeds of 450 km / h and above. It has a long service life, significant weight reduction effect, and convenient operation and maintenance. It can effectively solve the technical shortcomings of existing insulators and has good practicality and industrialization promotion value. Detailed Implementation

[0017] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0018] The present invention achieves the following technical solution through at least one embodiment: This invention provides a lightweight rod-shaped insulator with fatigue resistance and flashover resistance. The structure includes a composite core rod, sheath skirts, and end fittings. The specific fabrication and structure are as follows: 1. Preparation of composite mandrel The composite mandrel includes an inner core and an outer reinforcing layer. The inner core is made of epoxy resin-based composite material, and the raw materials are 55-65 parts by weight of epoxy resin, 18-25 parts by weight of curing agent, 8-15 parts by weight of nano-reinforcing component, 0.5-1 parts by weight of silane coupling agent, 0.3-0.6 parts by weight of organosilicon defoamer, and 0.2-0.4 parts by weight of internal release agent. Among them, the nano-reinforcing component is a mixture of nano-alumina and nano-silica in a mass ratio of 1-3:1-2. The outer reinforcing layer is woven from basalt fiber and glass fiber ply yarn. The mass ratio of basalt fiber to glass fiber in the basalt fiber and glass fiber ply yarn is 1-3:2, the weaving density is 18-26 threads / cm, the weaving structure is plain weave or twill weave, and the ply yarn specification is 300-500 tex. The preparation method of the composite mandrel is as follows: First, add the nano-reinforcing component of the formula to the silane coupling agent KH-550 and stir at high speed. Then, ultrasonically disperse for 30 minutes and dry to obtain the modified nano-reinforcing component. Preheat the epoxy resin to 45-50℃, and then mix it with the curing agent and the modified nano-reinforcing component at low speed. Vacuum degassing is performed for 15-20 minutes. Preheat the mold, add the material, close the mold, and pre-press to remove air. The pre-pressing pressure is 2-4MPa, and the pressure is held for 5-8 minutes. After removing the air bubbles, the material is cured at 150-160℃ and 10-12MPa for 1-1.5 hours under constant temperature and pressure. The material is then slowly cooled to 50-60℃ for demolding. The material is then kept at 110-120℃ for 1-1.2 hours to release internal stress and obtain the inner core. After plasma treatment of the outer reinforcing layer, it is impregnated with epoxy resin with the resin content controlled at 25±5%. After pre-baking at 80-100℃ to a semi-dry state, it is tightly wrapped around the inner core in a circumferential direction to ensure no wrinkles or gaps. The mold is closed and locked, and the temperature is increased to 140-150℃ at a gradient of 2-4℃ / min, the pressure is increased to 6-8MPa, the pressure is held for 30-60min, the pressure is released at a uniform rate, and the temperature is decreased to room temperature at a gradient of 2-3℃ / min to demold, forming an integrated composite mandrel. The total length of the prepared composite mandrel is 1200-1300mm and the diameter is 28±0.5mm. The core process parameters for plasma treatment are: radio frequency of 13.56MHz, radio power of 100-150W, processing time of 60-90s, vacuum degree of 20-50Pa, working gas of O2 / Ar (3:1) and gas flow rate of 15-25sccm.

[0019] 2. Preparation of the protective umbrella skirt The sheath and skirt are integrally injection molded using modified silicone rubber material. The modified silicone rubber material formula consists of 100 parts by weight of methyl vinyl silicone rubber, 25-35 parts by weight of hydrogenated nitrile butadiene rubber, 15-25 parts by weight of C16-C22 alkyl-grafted polydimethylsiloxane, 30-40 parts by weight of fumed silica, 12-18 parts by weight of wet-process modified fiber brucite, 4-8 parts by weight of needle-like nano zinc oxide, 1-2 parts by weight of zinc stearate, 2-4 parts by weight of hydroxyl silicone oil, 1-3 parts by weight of anti-aging agent, 0.6-1.2 parts by weight of bis(2,5) vulcanizing agent, and 0.2-0.3 parts by weight of CTP anti-scorching agent. The anti-aging agent is a mixture of benzotriazole and hindered phenolic antioxidant at a mass ratio of 1-2:1. The preparation method of the protective umbrella skirt includes the following steps: (1) Secret refining Add methyl vinyl silicone rubber and hydrogenated nitrile rubber to a closed internal mixer (rotor speed 35 r / min) and air mix for 2 min to fully melt the rubber compound. Add fumed silica, wet-modified fiber magnesia, and needle-shaped nano zinc oxide in two batches, with an interval of 5 min between each batch. Then, add zinc stearate and hydroxyl silicone oil. The mixing parameters are: temperature 120-130℃, atmospheric pressure, and time 30 min. Discharge the rubber into a two-roll mill. (2) Refining The roller temperature of the two-roll mill is controlled at 55±5℃, the front roller speed is 15r / min and the rear roller speed is 20r / min. Wrap the rollers for 4 minutes to ensure that the rubber compound completely covers the roller surface. Add the double 2,5 vulcanizing agent and CTP anti-scorching agent in sequence. Adjust the roller gap to 1.8mm and mix evenly for 4 minutes. Adjust the roller gap to 0.6mm and pass through the mill 4 times to ensure that the additives are completely dispersed and there is no agglomeration. Adjust the roller gap to 2.8mm, and then sheet the rubber compound. Let it stand at room temperature for 18 hours to eliminate internal stress and stabilize the rubber compound. (3) Granulation After standing, the rubber sheet is fed into a rubber granulator and cut into uniform rubber granules with a particle size of 2-3mm. (4) Injection molding A dedicated injection mold with an integrated mandrel is used. The mold has a horizontal parting structure and incorporates a mandrel positioning mechanism and a hot runner system. Before injection, the entire mold is heated, with the cavity temperature controlled at 163±2℃ and the mandrel positioning area temperature at 85±5℃. The temperature is maintained for 20 minutes to ensure uniformity. The cleaned composite mandrel is horizontally placed into the mold positioning mechanism and fixed by V-shaped positioning blocks and elastic ejector pins at both ends to ensure that the composite mandrel is centered and the coaxiality error is no more than 0.2mm. After mold closing, the clamping force is set to 1800kN. The mold design ensures the sheath thickness is 4±0.5mm, and the umbrella skirt has an aerodynamic alternating structure of large and small umbrellas, with the large umbrella diameter being 250-280mm, the small umbrella diameter being 180-200mm, and the umbrella spacing being 80-100mm. A silicone rubber-specific injection molding machine is used, with a screw length-to-diameter ratio (L / D) of 16:1. The barrel is divided into two sections: the hopper section has a temperature of 80-90℃, the front section has a temperature of 142±3℃, and the nozzle temperature is 158±2℃. Rubber granules are fed into the hopper and pre-plasticized by the screw, with the residence time of the granules in the barrel controlled to not exceed 3 minutes. The injection pressure is set to 8-10 MPa, the injection speed to 50-55 mm / s, the holding pressure to 6-8 MPa, and the holding time to 45-60 seconds. The rubber compound is rapidly injected into the outer cavity of the mandrel through a hot runner, with a mold filling time not exceeding 8 seconds. After the filling is completed, the in-mold vulcanization stage begins. The temperature is maintained at 163±2℃ for 600±50s to allow the silicone rubber material to cross-link and cure on the outer periphery of the core rod, forming a sheath skirt. After vulcanization, the mold is cooled for 4 minutes. After the product is shaped, the mold is opened, and the integrated insulator semi-finished product is taken out. The integrated insulator semi-finished product is then kept at 90±5℃ for 3 hours, and then naturally cooled to room temperature.

[0020] 3. Fitting connection and assembly The fittings are made of high-strength aluminum alloy with hot-dip galvanizing treatment. The zinc coating thickness is 85±5μm. Equalizing rings with a diameter of 300-320mm are further installed at both ends of the fittings. A digitally controlled crimping process is used to install the fittings at both ends of the composite core rod. The crimping pressure is 80-100MPa, and the crimping length is 50-60mm. A sealing sleeve made of high-temperature vulcanized silicone rubber is further installed at the connection between the sheath and the fitting, ensuring a tight fit with both the sheath and the fitting, thus completing the overall assembly of the rod-shaped insulator.

[0021] I. Materials and Reagents Epoxy impregnating adhesive, purchased from Zhongde Xinya Building Materials; The internal release agent was purchased from Greenlink (Jining) Chemical Technology. The curing agent was methylcyclohexanediamine (MCHDA), purchased from Shandong Jinshengtai Chemical Co., Ltd. Hydrogenated nitrile butadiene rubber, Mooney viscosity ML 1+4 (100℃) Controlled at 50-65; Methyl vinyl silicone rubber, Mooney viscosity ML 1+4 (125℃) Controlled between 45-70; C16-C22 alkyl-grafted polydimethylsiloxane, with alkyl carbon chains of C16 / C18 / C22, grafting rate ranging from 8-15%, and viscosity range from 300-1500 mPa·s; Fumed silica with a particle size of 20-50 nm and a specific surface area of ​​200-300 m² 2 / g; Wet-process modified fibrous brucite with an aspect ratio of 20-50 is coated with silane coupling agent KH560. The specific steps are as follows: After loosening and removing impurities, the fibrous brucite is heated to 65℃, and a 1.5% silane coupling agent KH560 solution (adjusted to pH 4.5, solvent is anhydrous ethanol / water (9 / 1, v / v)) is slowly added dropwise over a period of 15 min. The mixture is stirred at 800 rpm and reacted at a constant temperature for 60 min. After the reaction is completed, the mixture is naturally cooled to room temperature and centrifuged at 3000 rpm for 10 min to separate the modified fibrous brucite. The mixture is washed with deionized water until the pH of the filtrate is neutral and there is no residue. The filter cake is placed in a forced-air drying oven and dried at 100℃ for 6 h until the moisture content is <1%. After cooling, the mixture is gently broken up and passed through a 200-mesh sieve to obtain wet-process modified fibrous brucite. Needle-shaped nano-zinc oxide, with an aspect ratio of 10-15, a particle size of 30-60 nm, and a purity ≥99.5%; Hydroxyl silicone oil, with a hydroxyl content of 4-6% and a viscosity of 300-500 mPa·s; The 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is used as the 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a purity ≥95%. The CTP anti-scorching agent is cyclohexylthiophthalimide with a purity ≥98%; Unless otherwise specified, all other reagents and materials used are commercially available products.

[0022] II. Methods Unless otherwise specified, the methods used below are conventional methods known to those skilled in the art.

[0023] 1. Preparation of composite mandrel The composite mandrel includes an inner core and an outer reinforcing layer. The inner core is made of epoxy resin-based composite material, and the raw materials are 60 parts by weight of epoxy resin, 22 parts by weight of curing agent, 12 parts by weight of nano-reinforcing component, 0.8 parts by weight of silane coupling agent, 0.5 parts by weight of defoamer and 0.3 parts by weight of internal release agent. The nano-reinforcing component is a mixture of nano-alumina and nano-silica in a mass ratio of 1:2. The outer reinforcing layer is woven from a blend of basalt fiber and glass fiber yarn. The mass ratio of basalt fiber to glass fiber in the blended yarn is 3:2, the weaving density is 20 yarns / cm, the weaving structure is plain weave, and the specification of the blended yarn is 400 tex.

[0024] The preparation method of the composite mandrel is as follows: The nano-reinforcing component of the formula is first added to the silane coupling agent KH-550 and stirred at high speed, then ultrasonically dispersed for 30 minutes and dried to obtain the modified nano-reinforcing component. The epoxy resin is preheated to 45℃, and then mixed with the curing agent and the modified nano-reinforcing component at low speed and homogenized. Vacuum degassing is performed for 15 minutes. The mold is preheated, the material is added, the mold is closed, and pre-pressed to remove air. The pre-pressing pressure is 3MPa and held for 5 minutes. After removing the air bubbles, it is cured at 155℃ and 12MPa for 1.2 hours under constant temperature and pressure. It is then slowly cooled to 60℃ for demolding and kept at 120℃ for 1 hour to release internal stress and obtain the inner core. After plasma treatment of the outer reinforcing layer, it is impregnated with epoxy wetting resin with the resin content controlled at 25%. After pre-baking at 80-100℃ to a semi-dry state, it is tightly wrapped around the inner core in a circumferential direction to ensure no wrinkles or gaps. The mold is closed and locked, and the temperature is increased to 150℃ at a gradient of 2℃ / min, the pressure is increased to 8MPa, and the pressure is held for 45min. The pressure is released at a uniform rate and the temperature is decreased to room temperature at a gradient of 2℃ / min before demolding to form an integrated composite mandrel. The total length of the prepared composite mandrel is 1200mm and the diameter is 28±0.5mm. The core process parameters for plasma treatment are: radio frequency of 13.56MHz, radio power of 120W, processing time of 90s, vacuum degree of 25Pa, working gas of O2 / Ar (3:1) and gas flow rate of 20sccm. The composite mandrel prepared according to the above formula and preparation method is denoted as A-1; A-2: The difference between A-2 and composite mandrel A-1 is that the outer reinforcing layer is omitted; A-3: The difference between A-3 and A-1 composite mandrel is that A-3 is directly impregnated with epoxy resin without plasma treatment. A-4: The difference between A-4 and composite core rod A-1 is that the outer reinforcing layer is woven from a single glass fiber yarn with a weaving density of 20 yarns / cm, a plain weave structure, and a yarn specification of 400 tex.

[0025] According to the testing standard GB / T 19519-2014, the composite mandrels A-1 to A-4 were tested for tensile failure load, flexural failure load and elastic modulus using a universal testing machine. Five replicates were set up, and the average value of the results was taken and summarized in Table 1.

[0026] Table 1 Statistical Table of Results As can be seen from Table 1, the composite mandrel A-1 adopts a composite structure of epoxy resin-based composite material and basalt fiber-glass fiber mixed reinforcement layer. Through the composite enhancement of resin matrix and high-strength basalt fiber-glass fiber, and with the plasma surface modification of the outer reinforcement layer to optimize the interfacial compatibility of the two phases, the fiber reinforcement effect is fully utilized, and the mechanical strength, impact resistance and fatigue resistance of the composite mandrel are greatly improved.

[0027] 2. Preparation of the protective umbrella skirt The sheath and skirt are integrally injection molded using modified silicone rubber material. The formulation of the modified silicone rubber material is shown in Table 2 below: Table 2 Formulation Design of Modified Silicone Rubber Materials Based on the formulation of the modified silicone rubber material given in Table 2, the integrated insulator semi-finished products were prepared by referring to the following preparation methods for the sheath and skirt, and are denoted as YP-1 to YP-10.

[0028] The preparation method of the protective umbrella skirt includes the following steps: (1) Secret refining Methyl vinyl silicone rubber and hydrogenated nitrile rubber were added to a closed internal mixer with a rotor speed of 35 r / min and air-mixed for 2 min to fully melt the rubber compound. Modified reinforcing filler was added in two batches with an interval of 5 min between each batch. Then, zinc stearate and hydroxyl silicone oil were added. The mixing parameters were 130℃ temperature, normal pressure and time of 30 min. The rubber was then discharged into a two-roll mill. (2) Refining The roll temperature of the two-roll mill is controlled at 55±5℃, the front roll speed is 15r / min and the rear roll speed is 20r / min. Wrap the rolls for 4 minutes to ensure that the rubber compound completely covers the roll surface. Add the double 2,5 vulcanizing agent, CTP anti-scorching agent and anti-aging agent in sequence. Adjust the roll gap to 1.8mm and mix evenly for 4 minutes. Adjust the roll gap to 0.6mm and pass through the mill 4 times to ensure that the additives are completely dispersed and do not agglomerate. Adjust the roll gap to 2.8mm, and then sheet the product. Let it stand at room temperature for 18 hours to eliminate internal stress and stabilize the rubber compound. (3) Granulation After standing, the rubber sheet is fed into a rubber granulator and cut into uniform rubber granules with a particle size of 2-3mm. (4) Injection molding A dedicated injection mold with an integrated mandrel is used. The mold has a horizontal parting structure and incorporates a mandrel positioning mechanism and a hot runner system. Before injection, the entire mold is heated, with the cavity temperature controlled at 163±2℃ and the mandrel positioning area temperature at 85±5℃. The temperature is maintained for 20 minutes to ensure uniformity. The cleaned composite mandrel A-1 is horizontally placed into the mold positioning mechanism and fixed by V-shaped positioning blocks and elastic ejector pins at both ends to ensure that the composite mandrel A-1 is centered with a coaxiality error of no more than 0.2mm. After mold closing, the clamping force is set to 1800kN. Through mold design, the thickness of the protective sleeve is 4±0.5mm, the umbrella skirt is an aerodynamic alternating structure of large and small umbrellas, the diameter of the large umbrella is 280mm, the diameter of the small umbrella is 200mm, and the distance between the umbrellas is 100mm; A silicone rubber injection molding machine is used, with a screw length-to-diameter ratio (L / D) of 16:1. The barrel is divided into two sections: the hopper section has a temperature of 80-90℃, the front section has a temperature of 142±3℃, and the nozzle temperature is 158±2℃. Rubber granules are fed into the hopper and pre-plasticized by the screw, with the residence time of the granules in the barrel controlled to not exceed 3 minutes. The injection pressure is set to 10MPa, the injection speed to 50mm / s, the holding pressure to 6MPa, and the holding time to 45s. The rubber compound is rapidly injected into the outer cavity of the mandrel through a hot runner, with a mold filling time not exceeding 8s. After the mold filling is completed, the in-mold vulcanization stage begins. The temperature is maintained at 163±2℃ for 680±50s to allow the silicone rubber material to cross-link and cure on the outer periphery of the core rod, forming a sheath skirt. After vulcanization, the mold is cooled for 4 minutes. Once the product has set, the mold is opened, and the integrated insulator semi-finished product is removed. The integrated insulator semi-finished product is then kept at 90±5℃ for 3 hours, and then naturally cooled to room temperature.

[0029] First, corona aging tests were conducted on the prepared integrated insulator semi-finished products, namely YP-1 to YP-10: After the integrated insulator semi-finished products underwent a 100-hour corona aging test, the hydrophobic contact angle was measured using a contact angle tester, and the initial hydrophobic contact angle of the integrated insulator semi-finished products was also determined. The corona aging test conditions were 100 hours of corona aging test on the samples at 3.5 kV.

[0030] According to GB / T 19519-2014 standard, the integrated insulator semi-finished products obtained, namely YP-1 to YP-10, were subjected to 10 days of axial tension-tension alternating vibration loading. 7 Alternating vibration fatigue test.

[0031] The results are shown in Table 3.

[0032] Table 3. Statistical Analysis of Test Results As shown in Table 3, the initial hydrophobic contact angle of the integrated insulator semi-finished product YP-1 is 112.4°, and it still maintains 105.1° after 100 hours of corona aging, stably meeting the HC1 level hydrophobicity requirement. Other integrated insulator semi-finished products containing grafted siloxanes can stably meet the HC2 level and above hydrophobicity requirements after 100 hours of corona aging. In the vibration fatigue test, the integrated insulator semi-finished product YP-1, after 10 hours... 7 After repeated alternating vibrations, there was no breakage, deformation, or loosening, demonstrating excellent long-term mechanical stability.

[0033] 3. Fitting connection and assembly The integrated insulator semi-finished products obtained above, namely YP-1 to YP-10, are connected and assembled with fittings. The fittings are made of aluminum alloy material and hot-dip galvanized with a zinc layer thickness of 85±5μm. Equalizing rings with a diameter of 300mm are installed at both ends of the fittings. A digitally controlled crimping process is used to install the fittings at both ends of the composite core rod of the integrated insulator semi-finished product. The crimping pressure is 90MPa and the crimping length is 60mm. Furthermore, a sealing sleeve is set at the connection between the sheath and the fitting of the integrated insulator semi-finished product. The sealing sleeve is made of vulcanized silicone rubber and fits tightly with the sheath and fitting. The overall assembly of the rod-shaped insulator is completed to obtain the finished insulator. The fittings, equalizing rings and sealing sleeves can all be obtained through commercial channels.

[0034] According to GB / T 16927.1-2011, the above-obtained insulator products were subjected to lightning impulse dry withstand voltage test and power frequency wet withstand voltage test; according to GB / T 4585-2024, the insulator products were subjected to artificial pollution power frequency flashover voltage test (salt density 0.15 mg / cm³). 2 +Gray density 0.3mg / cm³ 2 The results are shown in Table 4.

[0035] Table 4. Statistical Analysis of Electrical Performance Test Results of Finished Insulators As shown in Table 4, electrical performance tests reveal that the finished insulator YP1 exhibits a lightning impulse dry withstand voltage of 650kV, a power frequency wet withstand voltage of 220kV, and an artificial pollution power frequency flashover voltage of 135kV. Short-chain C16-grafted polydimethylsiloxane effectively optimizes the hydrophobic stability of the interface. The ternary modified reinforcing filler, consisting of fumed silica, wet-process modified fiber magnesia, and needle-like nano zinc oxide, synergistically constructs a dense insulation network. The compounded anti-aging agent significantly delays the aging and degradation of the material. The synergistic effect of these three components gives the finished insulator YP1 excellent hydrophobicity, aging resistance, mechanical stability, and electrical insulation performance.

[0036] Furthermore, the environmental adaptability of the finished insulator YP1 was tested. Within a temperature range of -50℃ to +120℃, its performance showed no significant degradation. After 1000 hours of salt spray testing, the surface showed no corrosion or damage, and the insulation performance remained stable. After 2000 hours of strong ultraviolet radiation testing, the sheds showed no powdering or cracking, and the hydrophobicity level remained at HC1. The finished insulator YP1 was weighed, and the weight of a single piece was 8.0±0.5kg, which is lighter than traditional porcelain insulators. Accelerated aging tests showed that its service life can reach more than 10 years.

[0037] In summary, the rod-shaped insulator proposed in this invention can meet the speed-up requirements of electrified high-speed rails with speeds of 450 km / h and above. It has a long service life, significant lightweight effect, and convenient operation and maintenance. It can effectively solve the technical shortcomings of existing insulators and has good practicality and industrialization promotion value.

[0038] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A lightweight rod-shaped insulator with fatigue resistance and flashover resistance, comprising a composite core rod, a sheath skirt covering the outer periphery of the composite core rod, and fittings pressed onto both ends of the composite core rod, characterized in that, The composite mandrel consists of an epoxy resin-based composite inner core and an outer reinforcing layer woven from basalt fiber-glass fiber strands. The sheath and skirt are integrally injection molded from modified silicone rubber. The raw materials include, by weight, 100 parts of methyl vinyl silicone rubber, 25-35 parts of hydrogenated nitrile rubber, 15-25 parts of C16-C22 alkyl-grafted polydimethylsiloxane, 46-66 parts of modified reinforcing filler, 1-2 parts of zinc stearate, 2-4 parts of hydroxyl silicone oil, 1-3 parts of anti-aging agent, 0.6-1.2 parts of bis(2,5) vulcanizing agent, and 0.2-0.3 parts of CTP anti-scorching agent.

2. The lightweight rod-shaped insulator with fatigue resistance and flashover resistance according to claim 1, characterized in that, The raw materials of the epoxy resin-based composite inner core include, by weight, 55-65 parts epoxy resin, 18-25 parts curing agent, 8-15 parts nano-reinforcing components, 0.5-1 parts silane coupling agent, 0.3-0.6 parts organosilicon defoamer, and 0.2-0.4 parts internal release agent. The nano-reinforcing component is a mixture of nano-alumina and nano-silica in a mass ratio of 1-3:1-2.

3. A lightweight rod-shaped insulator with fatigue resistance and flashover resistance according to claim 1, characterized in that, In the basalt fiber-glass fiber ply yarn, the mass ratio of basalt fiber to glass fiber is 1-3:2, and the ply yarn specification is 300-500 tex; The outer reinforcing layer has a weave density of 18-26 threads / cm, and the weave structure is plain or twill.

4. A lightweight rod-shaped insulator with fatigue resistance and flashover resistance according to claim 1, characterized in that, The modified reinforcing filler comprises, by weight, 30-40 parts of fumed silica, 12-18 parts of wet-process modified fiber magnesia, and 4-8 parts of needle-shaped nano zinc oxide.

5. A lightweight rod-shaped insulator with fatigue resistance and flashover resistance according to claim 1, characterized in that, The anti-aging agent is a mixture of benzotriazole and hindered phenolic antioxidants at a mass ratio of 1-2:

1.

6. A method for preparing a lightweight rod-shaped insulator with fatigue resistance and flashover resistance as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of inner core: According to the formula, the nano-reinforcing component and silane coupling agent are stirred at high speed, ultrasonically dispersed and dried, mixed with preheated epoxy resin and curing agent, vacuum degassed, pre-pressed, high temperature and high pressure cured, demolded and heat-preserved to obtain the inner core; (2) Preparation of composite core rod: The outer reinforcing layer woven from basalt fiber-glass fiber strands is subjected to plasma treatment, impregnated with epoxy impregnation adhesive and pre-dried to semi-dry, and then wrapped around the inner core in a circumferential direction. After curing by heating and pressurizing and cooling to demold, an integrated composite core rod is obtained. (3) Preparation of sheath skirt: Methyl vinyl silicone rubber and hydrogenated nitrile rubber are mixed in an intensive manner, and modified reinforcing fillers and additives are added and mixed. After granulation, a special mold and injection molding machine are used to inject and vulcanize the mixture under set temperature and pressure to obtain an integrated insulator semi-finished product. (3) Fitting assembly: Press the fittings onto both ends of the composite core rod, and install the equalizing ring and sealing sleeve to complete the finished product assembly and obtain the lightweight rod-shaped insulator.

7. The method for preparing a lightweight rod-shaped insulator resistant to fatigue and flashover according to claim 6, characterized in that, In step (1), the process parameters for molding the inner core are as follows: the pre-pressure is 2-4 MPa, the pressure is held for 5-8 minutes, after the air bubbles are removed, the core is cured at 150-160℃ and 10-12 MPa for 1-1.5 hours under constant temperature and pressure, then slowly cooled to 50-60℃ for demolding, and then kept at 110-120℃ for 1-1.2 hours to release internal stress.

8. The method for preparing a lightweight rod-shaped insulator resistant to fatigue and flashover according to claim 6, characterized in that, The specific steps of step (2) are as follows: after plasma treatment of the outer reinforcing layer, epoxy impregnation adhesive is impregnated, the adhesive content is controlled to be 25±5%, and the inner core is pre-dried at 80-100℃ to a semi-dry state. Then, the inner core is tightly wrapped in a circumferential direction to ensure no wrinkles or gaps. The mold is closed and locked, and the temperature is increased to 140-150℃ at a gradient of 2-4℃ / min. The pressure is increased to 6-8MPa and held for 30-60min. The pressure is released at a uniform speed and the temperature is reduced to room temperature at a gradient of 2-3℃ / min before demolding to form a composite core rod with an integrated structure.

9. A method for preparing a lightweight rod-shaped insulator resistant to fatigue and flashover according to claim 6 or 8, characterized in that, In step (2), the core process parameters of plasma treatment are: radio frequency of 13.56MHz, radio power of 100-150W, processing time of 60-90s, vacuum degree of 20-50Pa, working gas of O2 / Ar (3:1) and gas flow rate of 15-25sccm.

10. The method for preparing a lightweight rod-shaped insulator resistant to fatigue and flashover according to claim 6, characterized in that, In step (3), the injection pressure for injection molding is set to 8-10 MPa, the injection speed to 50-55 mm / s, the holding pressure to 6-8 MPa, and the holding time to 45-60 s; the vulcanization temperature is 163±2℃, and the holding vulcanization time is 600±50 s.

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