Core rod for composite insulating crossarm and preparation method therefor

Abstract

The present invention belongs to the technical field of core rods for composite insulating crossarms, and particularly relates to a core rod for a composite insulating crossarm and a preparation method therefor. The core rod for a composite insulating crossarm comprises a polymer resin-hollow microsphere composite core and a fiber-cloth-reinforced polymer-resin-based composite layer, wherein the fiber-cloth-reinforced polymer-resin-based composite layer is laid on the outer surface of the polymer resin-hollow microsphere composite core in a directional manner, and the fiber-cloth-reinforced polymer-resin-based composite layer and the polymer resin-hollow microsphere composite core are integrated into one body by means of vacuum infiltration with a resin and curing; and the polymer resin-hollow microsphere composite core is a composite material core formed by curing the resin and hollow microspheres. Compared with a solid composite core, the core rod for a composite insulating crossarm in the present invention has a relatively low weight. Moreover, the composite core rod prepared by means of a vacuum infiltration process has a dense structure, and exhibits better dye penetration into materials, better water diffusion and a better dielectric strength as compared with a composite core rod formed by means of a pultrusion process.

Description

Composite Insulating Crossarm Core Rod and Its Preparation Method Technical Field

[0001] This invention belongs to the technical field of composite crossarm internal insulation core for overhead transmission lines or substations, specifically relating to composite insulated crossarm core rods and their preparation methods, and particularly to large-size, lightweight, high-insulation composite crossarm cores with voltage levels of 220kV and above and their preparation methods. Background Technology

[0002] Composite insulated crossarms operate outdoors for extended periods, frequently exposed to harsh weather conditions such as sun exposure, rain, wind, sandstorms, high temperatures, and extreme cold. This places high demands on the core insulation of the crossarms, requiring excellent resistance to moisture penetration, high and low temperatures, and high insulation performance. Furthermore, composite insulated crossarms for power lines need to withstand combined loads of tension, compression, bending, and torsion. As voltage levels increase, the structural height of the insulator also increases; therefore, to ensure the mechanical strength and stability of the insulator, the diameter of its core rod must be increased. The core rod diameter of composite insulated crossarms used in ultra-high voltage (UHV) projects is mostly [missing information]. The above-mentioned dimensions significantly increase the weight of the equipment, causing numerous inconveniences for construction and maintenance. At the same time, the "large size" also greatly increases the difficulty of mandrel molding. Currently, large-size cores mainly include single-rod cores, multi-rod cores, and hollow-filled cores. Large-size single-rod and multi-rod cores suffer from drawbacks such as high weight, poor economic efficiency, uneven curing leading to internal thermal stress concentration and cracking, and inconvenience in construction and maintenance due to their weight. While hollow cores can reduce the weight of the equipment, they have disadvantages such as poor sealing reliability, potential for internal moisture infiltration, and a large workload for maintenance. Another option is hollow composite material tubes filled with polyurethane foam; however, due to the poor moisture permeability resistance of polyurethane, internal core moisture absorption has led to internal breakdown accidents in the composite crossarm core. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing composite insulating crossarm core rods, such as increased weight due to their large size, which makes construction and maintenance inconvenient, and poor resistance to moisture and permeability. Therefore, this invention proposes a composite insulating crossarm core rod and its preparation method. The composite insulating crossarm core rod of this invention is integrally formed by vacuum impregnation of a polymer resin and hollow microsphere composite core layer and a fiber cloth-reinforced polymer resin-based composite layer with liquid resin, followed by curing and post-processing. The density of the polymer resin and hollow microsphere composite core layer is 0.3–0.6 g / cm³. 3 This process can effectively reduce the mass of composite mandrels. At the same time, the composite mandrels prepared by the vacuum impregnation process have a dense structure and few defects. Furthermore, the dye penetration, water diffusion, and dielectric strength of the material are all superior to those of composite mandrels formed by pultrusion.

[0004] The first aspect of this invention proposes a composite insulating crossarm core rod, which includes a polymer resin and hollow microsphere composite core and a fiber cloth reinforced polymer resin-based composite layer. The fiber cloth reinforced polymer resin-based composite layer is orientedly laid on the outer surface of the polymer resin and hollow microsphere composite core. The fiber cloth reinforced polymer resin-based composite layer and the polymer resin and hollow microsphere composite core are integrated by resin vacuum impregnation and curing. The polymer resin and hollow microsphere composite core is a composite material core formed by the curing of resin and hollow microspheres.

[0005] Preferably, the density of the polymer resin and hollow microsphere composite core is 0.3–0.6 g / cm³. 3 The density of the fiber-reinforced polymer resin-based composite layer is 2.0–2.2 g / cm³. 3 .

[0006] More preferably, the preparation method of the polymer resin and hollow microsphere composite core is as follows: mixing resin, curing agent, accelerator, toughening agent and hollow microspheres, subjecting the obtained mixed product to degassing treatment, injecting the degassed product into a cylindrical mold for curing, and obtaining the polymer resin and hollow microsphere composite core, wherein, based on the total mass of the resin, curing agent, accelerator, toughening agent and hollow microspheres as 100%, the content of hollow microspheres is 1.5-26%.

[0007] More preferably, the hollow microspheres have a diameter ≤10µm, and the hollow microspheres are micro / nano-scale polymer microspheres and / or glass microspheres; the micro / nano-scale polymer microspheres are polymethyl methacrylate microspheres and / or polyacrylonitrile microspheres; the resin is selected from one or more of epoxy resin, polyurethane resin, vinyl resin, unsaturated resin, phenolic resin, benzoxazine resin and nylon resin.

[0008] More preferably, the fiber-reinforced polymer resin-based composite layer includes a fiber cloth layup with a fiber aspect ratio of 10:1 and a fiber cloth layup with a fiber aspect ratio of 4:1. The method for directionally laying the fiber cloth-reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core is as follows: the fiber cloth layup with a fiber aspect ratio of 10:1 is wound and laid to a predetermined thickness on the outer surface of the polymer resin and hollow microsphere composite core, and the fiber cloth layup with a fiber aspect ratio of 4:1 is wound and laid to a predetermined thickness on the fiber cloth layup with a fiber aspect ratio of 10:1; the fiber cloth used for the fiber cloth layup with a fiber aspect ratio of 10:1 and the fiber cloth layup with a fiber aspect ratio of 4:1 is ECR glass fiber cloth, basalt fiber cloth or polyester fiber cloth.

[0009] More preferably, the fiber-reinforced polymer resin-based composite layer includes a fiber cloth layup with a fiber aspect ratio of 7:3. The method for directionally laying the fiber cloth-reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core is as follows: the fiber cloth layup with a fiber aspect ratio of 7:3 is wound and laid on the outer surface of the polymer resin and hollow microsphere composite core to a predetermined thickness; the fiber cloth used for the fiber cloth layup with a fiber aspect ratio of 7:3 is ECR glass fiber cloth, basalt fiber cloth or polyester fiber cloth.

[0010] A second aspect of this invention provides a method for preparing the composite insulating crossarm core rod described above, the method comprising the following steps:

[0011] A fiber cloth with a fiber aspect ratio of 10:1 is uniformly wrapped around the surface of the polymer resin and hollow microsphere composite core until a preset thickness is reached, thus obtaining the first fiber cloth-wrapped composite core.

[0012] A fiber cloth with a fiber aspect ratio of 4:1 is laid evenly around the surface of the composite core covered by the first fiber cloth until a preset thickness is reached, and then a composite core covered by the second fiber cloth is obtained.

[0013] A polyester fiber cloth of a predetermined thickness is wound around the surface of the composite core covered by the second fiber cloth, and then a polyethylene woven vacuum guide net of a predetermined thickness is wound around the surface of the polyester fiber cloth.

[0014] The resin is vacuum impregnated through the polyethylene woven vacuum guide net to impregnate the composite core covered with polyester fiber cloth and the second fiber cloth. The resin-impregnated polyethylene woven vacuum guide net, polyester fiber cloth and the composite core covered with the second fiber cloth are then cured to obtain a composite insulating crossarm core rod.

[0015] A third aspect of this invention provides a method for preparing the composite insulating crossarm core rod described above, the method comprising the following steps:

[0016] A fiber cloth with a fiber aspect ratio of 7:3 is laid and uniformly wrapped around the surface of the polymer resin and hollow microsphere composite core until the preset thickness is reached, resulting in a composite core covered with a third fiber cloth.

[0017] A polyester fiber cloth of a predetermined thickness is wound around the surface of the composite core covered by the third fiber cloth, and then a polyethylene woven vacuum guide net of a predetermined thickness is wound around the surface of the polyester fiber cloth; resin is vacuum impregnated through the polyethylene woven vacuum guide net to impregnate the composite core covered by the polyester fiber cloth and the third fiber cloth, and the resin-impregnated polyethylene woven vacuum guide net, polyester fiber cloth and third fiber cloth covered composite core are cured to obtain a composite insulating crossarm core rod.

[0018] Preferably, the device used for vacuum impregnation includes a vacuum casting mold, a container filled with liquid resin, a backflow preventer, and a vacuum pump. The container is connected to one end of the vacuum casting mold via a guide pipe, the backflow preventer is connected to the other end of the vacuum casting mold via a first outlet pipe, and the vacuum pump is connected to the backflow preventer via a second outlet pipe. During use, a composite core covered with a second fiber cloth and a third fiber cloth, which are sequentially wound with polyester fiber cloth and polyethylene woven vacuum guide net, is placed in the vacuum casting mold. The vacuum pump is turned on, and the passage composed of the backflow preventer, the vacuum pump, the first outlet pipe, and the second outlet pipe evacuates the vacuum casting mold. The container draws liquid resin into the vacuum casting mold through the guide pipe, and the liquid resin impregnates the composite core covered with the second fiber cloth and the third fiber cloth, which are sequentially wound with polyester fiber cloth and polyethylene woven vacuum guide net.

[0019] Preferably, the viscosity of the resin is 100–800 mPa·s; the curing conditions include: pre-curing at 90–110°C for 1–3 h, then curing at 120–140°C for 2–4 h, and curing at 130–150°C for 0.5–1.5 h.

[0020] The composite insulating crossarm core rod and its preparation method described in this invention have at least the following beneficial effects:

[0021] (1) The composite insulating crossarm core rod of the present invention adopts a two-layer structure, and the internal composite core adopts a material with a density of 0.3-0.6 g / cm³. 3 The polymer hollow microspheres and epoxy resin composite material has a density that is 1 / 6 to 1 / 7 of that of fiberglass, which can effectively reduce the weight of the composite mandrel. Compared with solid rods, it solves the technical problems of large-size composite cores being heavy, difficult to transport and construct. The composite mandrel prepared by vacuum impregnation process has a dense structure and few defects. The dye penetration, water diffusion and dielectric strength of the material are better than those of composite mandrels formed by pultrusion process. Moreover, compared with pultrusion process, it can produce mandrels with larger diameters and is more economical. In addition, the present invention also has technical advantages such as simple structure, convenient operation, low cost and structural safety.

[0022] (2) In this invention, the performance of the composite tube of the outer fiber cloth layer can be designed. By changing the fiber content ratio of the longitudinal and transverse directions of the fiber cloth, the strength of the outer composite material of the fiber cloth reinforced composite core rod can be designed to meet the longitudinal strength and circumferential stiffness of the composite crossarm under different usage conditions. At the same time, composite core rods of different diameters can be designed according to the usage requirements of the composite crossarm. Based on the diameter of the composite core rod and the stress conditions, the diameter of the central lightweight composite core and the thickness of the outer composite material can be designed to ensure that the composite core rod is the lightest and the economy is the best.

[0023] (3) In this invention, the composite core prepared by vacuum impregnation process has superior electrical properties, can pass the 12h dye penetration test, and has better leakage current and electrical breakdown strength than solid composite core rods of the same specification, and also has lower water absorption. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the structure of a fiber cloth layer with a fiber aspect ratio of 10:1 and a composite core of polymer resin and hollow microspheres in one embodiment of the present invention.

[0025] Figure 2 is a schematic diagram of the structure of a composite core covered by a fiber cloth layer with a fiber aspect ratio of 4:1 and a first fiber cloth in one embodiment of the present invention.

[0026] Figure 3 is a schematic diagram of the structure of a composite core covered with a second fiber cloth according to one embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of the structure of a composite core preform according to one embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of the structure of a device used for vacuum impregnation according to one embodiment of the present invention.

[0029] Figure reference numerals: 1. Polymer resin and hollow microsphere composite core; 2. Fiber cloth layup with a fiber aspect ratio of 10:1; 3. Fiber cloth layup with a fiber aspect ratio of 4:1; 4. Composite core covered by the first fiber cloth; 5. Composite core covered by the second fiber cloth; 6. Vacuum injection molding mold; 7. Container; 8. Backflow preventer; 9. Vacuum pump; 10. Guide tube; 11. First outlet tube; 12. Second outlet tube; 13. Composite core preform. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0031] The first aspect of this invention proposes a composite insulating crossarm core rod, which includes a polymer resin and hollow microsphere composite core 1 and a fiber cloth reinforced polymer resin-based composite layer. The fiber cloth reinforced polymer resin-based composite layer is orientedly laid on the outer surface of the polymer resin and hollow microsphere composite core 1. The fiber cloth reinforced polymer resin-based composite layer and the polymer resin and hollow microsphere composite core 1 are integrally formed by resin vacuum impregnation and curing. The polymer resin and hollow microsphere composite core 1 is a composite material core formed by the curing of resin and hollow microspheres.

[0032] In a specific embodiment of the composite insulating crossarm core rod of the present invention, the density of the polymer resin and hollow microsphere composite core 1 is 0.3-0.6 g / cm³. 3 For example, it can be 0.3g / cm 3 0.4g / cm 3 0.5g / cm 3 or 0.6g / cm 3 The density of the fiber-reinforced polymer resin-based composite layer is 2.0–2.2 g / cm³. 3 For example, it can be 2.0 g / cm³. 3 2.1g / cm 3 Or 2.2g / cm 3 In this invention, the core material inside the composite insulating crossarm core rod uses a density of 0.3–0.6 g / cm³. 3 The polymer resin and hollow microsphere composite core 1 has a density that is 1 / 6 to 1 / 7 that of fiberglass material, and a binding density of 2.0 to 2.2 g / cm³. 3 The fiber cloth reinforced polymer resin-based composite layer can effectively reduce the weight of the composite core rod. Compared with solid rods, it solves the technical problems of large-size composite cores being heavy, difficult to transport and construct.

[0033] In a specific embodiment of the composite insulating crossarm core rod of the present invention, the preparation method of the polymer resin and hollow microsphere composite core 1 is as follows: The resin, curing agent, accelerator, toughening agent, and hollow microspheres are mixed uniformly at room temperature. The resulting mixture is degassed at 60–70°C for 30–45 min. The degassed product is injected into a cylindrical mold, and then cured sequentially at 90°C for 1 h, 100°C, and 120°C for 2 h each. After curing, it is naturally cooled to room temperature, and demolded to obtain the polymer resin and hollow microsphere composite core. The hollow microsphere content is 1.5–26% based on the total mass of the resin, curing agent, accelerator, toughening agent, and hollow microspheres as 100%. When the hollow microsphere content is controlled at 1.5–26%, the density of the final polymer resin and hollow microsphere composite core 1 can be 0.3–0.6 g / cm³.3 Within the specified range. In this document, the content of the hollow microspheres can be 1.5%, 5%, 7.5%, 10%, 15%, 20%, or 26%, based on the total mass of the resin, curing agent, accelerator, toughening agent, and hollow microspheres as 100%.

[0034] In this document, the resin may be a thermosetting resin and / or a thermoplastic resin; preferably, the resin is selected from one or more of epoxy resin, polyurethane resin, vinyl resin, unsaturated resin, phenolic resin, benzoxazine resin and nylon resin.

[0035] In this document, the diameter of the hollow microspheres is ≤10 μm, and the hollow microspheres are micro / nano-scale polymer microspheres and / or glass microspheres; the micro / nano-scale polymer microspheres are polymethyl methacrylate microspheres and / or polyacrylonitrile microspheres.

[0036] In this document, the curing agent can be an epoxy curing agent, specifically, the curing agent is hexamethyltetrahydrophthalic anhydride; the accelerator can be an epoxy curing accelerator, specifically, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30); the toughening agent can be an epoxy toughening agent, specifically, the toughening agent can be polypropylene glycol diglycidyl ether and / or linoleic acid dimer diglycidyl ether.

[0037] In one specific embodiment of the composite insulating crossarm core rod of the present invention, the fiber cloth reinforced polymer resin-based composite layer can be two or more fiber cloth lay-ups. Specifically, for example, the fiber cloth reinforced polymer resin-based composite layer includes a fiber cloth lay-up 2 with a fiber aspect ratio of 10:1 and a fiber cloth lay-up 3 with a fiber aspect ratio of 4:1. The method of directionally laying the fiber cloth reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core 1 is as follows: the fiber cloth lay-up 2 with a fiber aspect ratio of 10:1 is wound and laid on the outer surface of the polymer resin and hollow microsphere composite core 1 to a predetermined thickness, and the fiber cloth lay-up 3 with a fiber aspect ratio of 4:1 is wound and laid on the fiber cloth lay-up 2 with a fiber aspect ratio of 10:1 to a predetermined thickness, as shown in Figures 1 and 2.

[0038] In this paper, directional layup refers to the design of the longitudinal and circumferential stiffness of the outer composite material tube by combining different longitudinal and transverse fiber fabrics. The fiber fabric reinforces the anisotropy of the polymer resin-based composite layer. The higher the fiber content in a particular direction, the greater the strength in that direction. Because high longitudinal strength is required, a high longitudinal fiber content is selected. The fiber fabric with a high longitudinal fiber content on the market is the fiber fabric layup 2 with a fiber aspect ratio of 10:1. The purpose of using the fiber fabric layup 3 with a fiber aspect ratio of 4:1 is to increase the circumferential fiber content and improve the circumferential strength of the material. The fiber fabrics used in the fiber fabric layup 2 with a fiber aspect ratio of 10:1 and the fiber fabric layup 3 with a fiber aspect ratio of 4:1 are ECR glass fiber cloth, basalt fiber cloth, or polyester fiber cloth.

[0039] In another specific embodiment of the composite insulating crossarm core rod of the present invention, the longitudinal and transverse fiber layup ratios can be customized. A composite material tube with designed longitudinal and transverse properties can be obtained through a fiber cloth with a layup structure. Specifically, for example, the fiber cloth reinforced polymer resin-based composite layer includes a fiber cloth layup with a fiber aspect ratio of 7:3. The method for directionally laying the fiber cloth reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core 1 is as follows: the fiber cloth layup with a fiber aspect ratio of 7:3 is wound and laid to a predetermined thickness on the outer surface of the polymer resin and hollow microsphere composite core 1, as shown in Figure 4, thereby achieving a balance between the longitudinal strength and circumferential stiffness of the outer composite material tube. The fiber cloth used for the fiber cloth layup with a fiber aspect ratio of 7:3 is ECR glass fiber cloth, basalt fiber cloth, or polyester fiber cloth.

[0040] In this paper, the fiber aspect ratio refers to the ratio of longitudinal fiber content to transverse fiber content; here, longitudinal refers to the axial direction of the polymer resin and hollow microsphere composite core 1, and transverse refers to the circumferential direction of the polymer resin and hollow microsphere composite core 1.

[0041] A second aspect of this invention provides a method for preparing the composite insulating crossarm core rod described above, the method comprising the following steps:

[0042] A fiber cloth layer 2 with a fiber aspect ratio of 10:1 is uniformly wound and wrapped around the surface of the polymer resin and hollow microsphere composite core 1. During the wrapping process, the fiber cloth must be flat and tightly adhered, as shown in Figure 1. After reaching the preset fiber thickness, a composite core 4 covered with the first fiber cloth is obtained. A fiber cloth layer 3 with a fiber aspect ratio of 4:1 is then uniformly wound and wrapped around the surface of the composite core 4 covered with the first fiber cloth. During the wrapping process, the fiber cloth is also kept flat and tightly adhered to the surface of the composite core, as shown in Figure 2. After reaching the preset fiber thickness, a composite core 5 covered with the second fiber cloth is obtained, as shown in Figure 3. A polyester fiber cloth of a predetermined thickness is then wound around the surface of the composite core 5 covered with the second fiber cloth. A polyethylene woven vacuum guide net of a set thickness is wound around the surface to obtain a composite core preform 13, as shown in Figure 4. The polyester fiber cloth is used to ensure the flatness of the fiber cloth forming surface underneath, and at the same time, it isolates the polyethylene woven vacuum guide net from the composite material during the liquid resin curing process. It is embedded in the fiber cloth composite material, which facilitates the separation of the polyester fiber cloth and the polyethylene guide net from the composite material after curing. The composite core preform 13 is impregnated with liquid resin under vacuum conditions. The resin passes through the polyethylene woven vacuum guide net to impregnate the composite core 5 covered by the polyester fiber cloth and the second fiber cloth. The resin-impregnated polyethylene woven vacuum guide net, the composite core 5 covered by the polyester fiber cloth and the second fiber cloth are cured to obtain a composite insulating crossarm core rod.

[0043] A third aspect of this invention provides a method for preparing the composite insulating crossarm core rod described above, the method comprising the following steps:

[0044] A fiber cloth with a fiber aspect ratio of 7:3 is laid and uniformly wrapped around the surface of the polymer resin and hollow microsphere composite core 1. During the wrapping process, the fiber cloth must be flat and tightly adhered. After reaching the preset fiber thickness, a composite core covered with a third fiber cloth is obtained. A polyester fiber cloth of a set thickness is wound around the surface of the composite core covered with the third fiber cloth. Then, a polyethylene woven vacuum guide net of a set thickness is wound around the surface of the polyester fiber cloth. The resin is vacuum impregnated through the polyethylene woven vacuum guide net to impregnate the composite core covered with the polyester fiber cloth and the third fiber cloth. The composite core covered with the third fiber cloth and the impregnated polyethylene woven vacuum guide net are cured to obtain a composite insulating crossarm core rod.

[0045] In a specific embodiment of the preparation method of the composite insulating crossarm core rod of the present invention, the device used for vacuum impregnation is shown in Figure 5. This device includes a vacuum casting mold 6, a container 7 containing liquid resin, a backflow preventer 8, and a vacuum pump 9. One end of the container 7 is connected to the vacuum casting mold 6 via a guide pipe 10. The other end of the backflow preventer 8 is connected to the vacuum casting mold 6 via a first outlet pipe 11. The vacuum pump 9 is connected to the backflow preventer 8 via a second outlet pipe 12. During use, the composite insulating crossarm core rod is wrapped with a second fiber cloth sequentially wound with polyester fiber cloth and a polyethylene woven vacuum guide net. The composite core 5 or the composite core covered with the third fiber cloth is placed in the vacuum injection molding mold 6. The vacuum pump 9 is turned on, and the passage composed of the backflow preventer 8, the vacuum pump 9, the first outlet pipe 11 and the second outlet pipe 12 is used to evacuate the vacuum injection molding mold 6. The container 7 draws liquid resin into the vacuum injection molding mold 6 through the guide pipe 10. The backflow preventer 8 is used to prevent the liquid resin in the vacuum injection molding mold 6 from flowing back. The liquid resin vacuum impregnates the composite core 5 or the composite core covered with the second fiber cloth or the third fiber cloth, which is wrapped with polyester fiber cloth and polyethylene woven vacuum guide net in sequence.

[0046] Specifically, the left end of the guide tube 10 should be located at the bottom of the container 7 containing liquid resin, the right end of the guide tube 10 should be located at the lower left end of the vacuum injection molding mold 6, the left end of the first outlet tube 11 should be located at the upper right end of the vacuum injection molding mold 6, the right end of the first outlet tube 11 should be located at the bottom of the backflow preventer 8, and the left end of the second outlet tube 12 should be located at the top of the backflow preventer 8.

[0047] In a specific embodiment of the preparation method of the composite insulating crossarm core rod of the present invention, the composite core 5 or the composite core covered with a second fiber cloth impregnated with resin and the composite core covered with a third fiber cloth are heated and cured together with a vacuum injection molding mold 6. The curing conditions include: pre-curing at 90-110℃ for 1-3 hours, then curing at 120-140℃ for 2-4 hours, and curing at 130-150℃ for 0.5-1.5 hours respectively; then the outer mold, polyethylene guide net and polyester fiber cloth are removed to obtain a semi-finished composite core rod for the composite crossarm, which is then post-processed on a lathe to obtain the final composite insulating crossarm core rod. In this article, the lathe post-processing refers to machining to the designed external dimensions and wall thickness, while ensuring the surface accuracy and smoothness.

[0048] In this paper, the liquid resin material introduced into container 7 should be a prepared resin adhesive with a room temperature gel time of not less than 3 hours, a viscosity of 100-800 mPa·s, and the resin should be degassed as much as possible before being poured into container 7.

[0049] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0050] Example 1

[0051] This embodiment discloses a 500kV composite insulating crossarm core rod and its preparation method. As shown in Figure 1, a fiber cloth with a fiber aspect ratio of 10:1 is laid on a diameter... A 6m long polymer resin and hollow microsphere composite core 1 are uniformly wound and laid on the outer surface until the thickness of the fiber cloth layer 2 with a fiber aspect ratio of 10:1 reaches 12mm, resulting in a first fiber cloth-covered composite core 4. Then, as shown in Figure 2, a fiber cloth with a fiber aspect ratio of 4:1 is uniformly wound and laid on the outer surface of the first fiber cloth-covered composite core 4 until the thickness of the fiber cloth layer 3 with a fiber aspect ratio of 4:1 reaches 3mm, resulting in a second fiber cloth-covered composite core 5. The structure of the second fiber cloth-covered composite core 5 is shown in Figure 3. A layer of polyester fiber cloth and a polyethylene woven microsphere are uniformly and tightly wound from the inside to the outside on the outer surface of the second fiber cloth-covered composite core 5. The hollow guide net is used to obtain a composite core pre-product 13, as shown in Figure 4. The composite core pre-product 13 is placed into a pre-made vacuum injection molding mold 6, and the prepared epoxy resin containing curing agent and accelerator is injected into the vacuum injection molding mold 6 according to the vacuum impregnation process shown in Figure 5 to fully impregnate the sample. After the fiber cloth is fully impregnated, the resin-impregnated fiber cloth composite core and the vacuum injection molding mold 6 are heated and cured together. First, it is pre-cured at 100℃ for 2 hours, then cured at 130℃ for 3 hours and at 140℃ for 1 hour respectively. After curing, it is naturally cooled to room temperature, and the outer mold, polyethylene guide net and polyester fiber cloth are removed to obtain a composite core rod semi-finished product for composite crossarm. Then, it is machined on a lathe to obtain an outer diameter of Lightweight, high-insulation composite crossarm core rod with a length of 6000mm.

[0052] Compared with the 500kV solid composite core, the lightweight high-insulation composite crossarm core rod prepared by this invention shows significant technical advantages in electrical and basic performance. Its leakage current, insulation breakdown strength, dye penetration, water absorption rate and apparent density are significantly better than those of the traditional solid composite core rod, and it has good economic value. The results are shown in Table 1.

[0053] Table 1. Performance Comparison of 500kV Composite Core and Composite Insulation Crossarm Core Rod of the Same Specification

[0054] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite insulating crossarm core rod, characterized in that, It includes a polymer resin and hollow microsphere composite core (1) and a fiber cloth reinforced polymer resin-based composite layer. The fiber cloth reinforced polymer resin-based composite layer is orientedly laid on the outer surface of the polymer resin and hollow microsphere composite core (1). The fiber cloth reinforced polymer resin-based composite layer and the polymer resin and hollow microsphere composite core (1) are integrated by resin vacuum impregnation and curing. The polymer resin and hollow microsphere composite core (1) is a composite material core formed by curing the resin and hollow microspheres.

2. The composite insulating crossarm core rod according to claim 1, characterized in that, The density of the polymer resin and hollow microsphere composite core (1) is 0.3-0.6 g / cm³. 3 The density of the fiber-reinforced polymer resin-based composite layer is 2.0–2.2 g / cm³. 3 .

3. The composite insulating crossarm core rod according to claim 2, characterized in that, The preparation method of the polymer resin and hollow microsphere composite core (1) is as follows: the resin, curing agent, accelerator, toughening agent and hollow microspheres are mixed, the resulting mixed product is then subjected to degassing treatment, and the degassed product is injected into a cylindrical mold for curing to obtain the polymer resin and hollow microsphere composite core (1). The content of the hollow microspheres is 1.5-26% based on the total mass of the resin, curing agent, accelerator, toughening agent and hollow microspheres as 100%.

4. The composite insulating crossarm core rod according to claim 3, characterized in that, The diameter of the hollow microspheres is ≤10 μm, and the hollow microspheres are micro / nano-scale polymer microspheres and / or glass microspheres; The micro-nano polymer beads are polymethyl methacrylate beads and / or polyacrylonitrile beads. The resin is selected from one or more of epoxy resin, polyurethane resin, vinyl resin, unsaturated resin, phenolic resin, benzoxazine resin and nylon resin.

5. The composite insulating crossarm core rod according to claim 2, characterized in that, The fiber-reinforced polymer resin-based composite layer includes a fiber fabric layup (2) with a fiber aspect ratio of 10:1 and a fiber fabric layup (3) with a fiber aspect ratio of 4:

1. The method for directionally laying the fiber-reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core (1) is as follows: A fiber cloth layer (2) with a fiber aspect ratio of 10:1 is wound and laid to a predetermined thickness on the outer surface of the polymer resin and hollow microsphere composite core (1), and a fiber cloth layer (3) with a fiber aspect ratio of 4:1 is wound and laid to a predetermined thickness on the fiber cloth layer (2) with a fiber aspect ratio of 10:

1. The fiber cloth used in the fiber cloth layup (2) with a fiber aspect ratio of 10:1 and the fiber cloth layup (3) with a fiber aspect ratio of 4:1 is ECR glass fiber cloth, basalt fiber cloth or polyester fiber cloth.

6. The composite insulating crossarm core rod according to claim 2, characterized in that, The fiber-reinforced polymer resin-based composite layer includes a fiber cloth layup with a fiber aspect ratio of 7:

3. The method for directionally laying the fiber-reinforced polymer resin-based composite layer on the outer surface of the polymer resin and hollow microsphere composite core (1) is as follows: A fiber cloth with a fiber aspect ratio of 7:3 is laid on the outer surface of the polymer resin and hollow microsphere composite core (1) to a predetermined thickness. The fiber cloth used in the fiber cloth layup with a fiber aspect ratio of 7:3 is ECR glass fiber cloth, basalt fiber cloth or polyester fiber cloth.

7. A method for preparing the composite insulating crossarm core rod according to claim 5, characterized in that, The method includes the following steps: A fiber cloth layer (2) with a fiber aspect ratio of 10:1 is uniformly wrapped around the surface of the polymer resin and hollow microsphere composite core (1) until a preset thickness is reached, and a composite core (4) covered by the first fiber cloth is obtained. A fiber cloth layer (3) with a fiber aspect ratio of 4:1 is uniformly wrapped around the surface of the composite core (4) covered by the first fiber cloth. After reaching a preset thickness, a composite core (5) covered by the second fiber cloth is obtained. A polyester fiber cloth of a set thickness is wound around the surface of the composite core (5) covered by the second fiber cloth, and then a polyethylene woven vacuum guide net of a set thickness is wound around the surface of the polyester fiber cloth. The resin is vacuum impregnated through the polyethylene woven vacuum guide net to the composite core (5) covered by the polyester fiber cloth and the second fiber cloth. The resin-impregnated polyethylene woven vacuum guide net, the composite core (5) covered by the polyester fiber cloth and the second fiber cloth is then cured to obtain a composite insulating crossarm core rod.

8. A method for preparing the composite insulating crossarm core rod according to claim 6, characterized in that, The method includes the following steps: A fiber cloth with a fiber aspect ratio of 7:3 is laid and uniformly wrapped around the surface of the polymer resin and hollow microsphere composite core (1) until the preset thickness is reached, and a composite core covered with a third fiber cloth is obtained. A polyester fiber cloth of a predetermined thickness is wound around the surface of the composite core covered by the third fiber cloth, and then a polyethylene woven vacuum guide net of a predetermined thickness is wound around the surface of the polyester fiber cloth. The resin is vacuum impregnated through the polyethylene woven vacuum guide net to impregnate the composite core covered with polyester fiber cloth and third fiber cloth. The resin-impregnated polyethylene woven vacuum guide net, polyester fiber cloth and third fiber cloth-covered composite core are then cured to obtain a composite insulating crossarm core rod.

9. The method for preparing the composite insulating crossarm core rod according to claim 7 or 8, characterized in that, The device used for vacuum impregnation includes a vacuum injection molding mold (6), a container (7) containing liquid resin, a backflow preventer (8), and a vacuum pump (9). The container (7) is connected to one end of the vacuum injection molding mold (6) through a guide pipe (10), the backflow preventer (8) is connected to the other end of the vacuum injection molding mold (6) through a first outlet pipe (11), and the vacuum pump (9) is connected to the backflow preventer (8) through a second outlet pipe (12). During use, the composite core (5) wrapped with a second fiber cloth and a third fiber cloth, which are sequentially wound with polyester fiber cloth and polyethylene woven vacuum guide net, is placed in the vacuum injection molding mold (6). The vacuum pump (9) is turned on, and the vacuum injection molding mold (6) is evacuated by the passage composed of the backflow preventer (8), the vacuum pump (9), the first outlet pipe (11) and the second outlet pipe (12). The container (7) draws liquid resin into the vacuum injection molding mold (6) through the guide pipe (10). The liquid resin vacuum impregnates the composite core (5) wrapped with a second fiber cloth and a third fiber cloth, which are sequentially wound with polyester fiber cloth and polyethylene woven vacuum guide net.

10. The method for preparing the composite insulating crossarm core rod according to claim 7 or 8, characterized in that, The viscosity of the resin is 100–800 mPa·s; The curing conditions include: pre-curing at 90–110°C for 1–3 hours, followed by curing at 120–140°C for 2–4 hours and at 130–150°C for 0.5–1.5 hours.

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