Composite insulator epoxy resin core rod surface lossless roughening process

Abstract

The invention relates to the technical field of electrical equipment manufacturing, and particularly discloses a composite insulator epoxy resin core rod surface lossless roughening process. According to the technology, in the thermocuring drawing process of an epoxy resin core rod or after cooling forming, pretreated inorganic powder is splashed or fixed to the surface of the core rod through a bonding layer by means of airflow pressure. The inorganic particles are embedded into or attached to the surface layer of the resin, so that the physical roughness of the core rod is remarkably improved on the premise that the surface structure integrity of the core rod is guaranteed, and microcracks and glass fiber fractures are not generated, and therefore, stable mechanical interlocking anchor points are provided for a subsequently coated silicon rubber sheath, and the interface bonding strength with the silicon rubber sheath is enhanced. According to the technology, the problems of stress concentration and interface defects caused by a traditional mechanical scraping technology are effectively solved, the operation reliability of the composite insulator is improved, and good application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of power equipment manufacturing technology, and more specifically, to a non-destructive roughening process for the surface of epoxy resin core rods of composite insulators. Background Technology

[0002] Composite insulators are crucial insulation devices in power lines and transmission and transformation equipment, and their operational stability directly affects the safety of the power grid. The main components of a composite insulator include a glass fiber reinforced epoxy resin core rod, a silicone rubber sheath and sheds surrounding the core rod, and end fittings for connecting conductors. The silicone rubber sheath, tightly wrapped around the surface of the epoxy resin core rod, is a key structure and material protecting it from environmental corrosion. Currently, epoxy resin core rods are commonly manufactured using a thermosetting drawing process. This process produces an extremely smooth surface on the epoxy resin core rod, making it difficult to form a strong bond with the silicone rubber material and its auxiliary adhesives.

[0003] To improve the adhesion between the silicone rubber sheath and the epoxy resin core rod, existing technologies typically employ mechanical scraping to physically score the smooth surface of the core rod, creating a rough surface to enhance the mechanical interlocking and adhesive strength between the core rod and the silicone rubber. However, this mechanical scraping process has significant drawbacks in practical applications: it disrupts the natural curing structure of the epoxy resin surface, and the irregular holes and cracks created on the epoxy resin core rod surface become stress concentration points for further deterioration. In particular, the scraping process easily damages the reinforcing glass fibers embedded in the epoxy resin. The broken glass fibers create easily breakable and movable floating fibers at the interface between the sheath and the core rod, resulting in air gap defects at the interface. During long-term operation, these interface defects gradually develop and expand under the influence of electric field and mechanical stress, causing interface decay and ultimately leading to mechanical fracture or electrical failure of the composite insulator. Summary of the Invention

[0004] To overcome the aforementioned deficiencies of existing technologies, this invention provides a non-destructive surface roughening process for epoxy resin core rods of composite insulators. This process achieves non-destructive surface roughening by sputtering or adhesive bonding of inorganic powder. This method utilizes powder particles to construct physical anchor points on the core rod surface, forming a mechanically interlocking structure and enhancing bonding strength. It effectively avoids damage to the epoxy resin core rod surface caused by mechanical scratching processes, while simultaneously increasing the surface roughness of the epoxy resin core rod and strengthening the interfacial bonding strength between the epoxy resin core rod and silicone rubber.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A non-destructive roughening process for the surface of epoxy resin core rods of composite insulators includes the following steps:

[0007] Step 1: Perform surface pretreatment on the inorganic powder to improve its surface reactivity;

[0008] Step 2: A surface roughening process is used to fix the pretreated inorganic powder onto the surface of the epoxy resin mandrel to improve the surface roughness of the epoxy resin mandrel.

[0009] Step two includes any one of the following process schemes:

[0010] Option 1: In the process of thermosetting and drawing epoxy resin mandrels, the epoxy resin mandrels that have left the heating pipe and are in a state of not being fully solidified are sent into an airflow sandblasting device. Inorganic powder is sprayed and embedded into the surface of the epoxy resin mandrels by airflow pressure. As the epoxy resin mandrels cool and solidify, the inorganic powder is fixed.

[0011] Option 2: Coat the surface of the cooled and molded epoxy resin mandrel with epoxy resin adhesive to form an adhesive layer, spray inorganic powder onto the adhesive layer, and then fix the inorganic powder with thermosetting epoxy resin adhesive.

[0012] As a further aspect of the present invention, the technical means for surface pretreatment of inorganic powder in step one is one or more of the following: plasma treatment, solid-phase stirring treatment in ozone atmosphere, nitric acid immersion treatment, concentrated sulfuric acid immersion treatment with a concentration greater than 90%, and hydrogen peroxide immersion treatment.

[0013] As a further aspect of the present invention, the inorganic powder is one or a combination of several of the following particles: silicon dioxide particles, wollastonite particles, silicate particles, alumina particles, aluminum nitride particles, and silicon carbide particles.

[0014] As a further aspect of the present invention, the inorganic powder coating density on the surface of the epoxy resin mandrel is from 40 particles per square centimeter to 60,000 particles per square centimeter.

[0015] As a further aspect of the present invention, after step two is completed, the surface of the roughened epoxy resin core rod is coated with silicone rubber adhesive or a special interface modifier for composite insulator core rods.

[0016] As a further aspect of the present invention, the particle size of the inorganic powder is from 1 micrometer to 100 micrometers.

[0017] Compared with the prior art, the beneficial effects of the non-destructive roughening process for the surface of the epoxy resin core rod of the composite insulator of the present invention are as follows:

[0018] This invention fixes inorganic powder particles onto the surface of an epoxy resin mandrel, causing the particles to be uniformly embedded or bonded to the mandrel surface. Compared to the smooth-surfaced mandrels produced by traditional thermosetting drawing processes, these inorganic particles distributed on the surface significantly improve the surface roughness of the mandrel, providing "mechanical interlocking" anchor points for bonding silicone rubber, and effectively enhancing the bond strength between the epoxy resin mandrel and the silicone rubber sheath.

[0019] This invention employs an airflow sandblasting or surface coating followed by sandblasting process to achieve non-destructive roughening of the core rod surface, allowing particles to be fixed to the surface without disrupting the continuity of the resin matrix. Compared to existing methods that use mechanical scraping to create hard scratches on the core rod surface, the epoxy resin core rod surface roughened by this process will not exhibit destructive scratches, loose fibers, or other defects or mechanical damage. This eliminates the potential for micro-cracks at the epoxy resin core rod-silicone rubber sheath interface, improving the operational reliability of composite insulators in complex power environments.

[0020] This invention designs two technical solutions: online sandblasting and offline adhesive-coated sandblasting, which can flexibly adjust the powder fixation method according to the curing state of the mandrel. Unlike the potential process limitations of traditional processing methods, this invention has extremely strong process compatibility. Solution 1 can be seamlessly integrated into the existing thermosetting and drawing process of glass fiber reinforced epoxy resin mandrels, utilizing residual heat to achieve automated online modification; while Solution 2 can be applied to the modification and upgrading of already cooled and formed finished mandrels. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process for non-destructive roughening of the surface of an epoxy resin core rod for a composite insulator according to the present invention.

[0022] Figure 2 This is a process flow diagram for surface roughening in Embodiment 1 of the present invention.

[0023] Figure 3 This is a process flow diagram for surface roughening in Embodiment 2 of the present invention.

[0024] Figure 4 These are partial optical photographs of the samples before and after the surface roughening process in Example 2 of the present invention.

[0025] Figure 5 Ink-marked photographs of the surface roughness of samples before and after the surface roughening process in Embodiment 2 of the present invention.

[0026] Figure 6 This is a sample image of the epoxy resin board-silicone rubber bonding strength test specimen manufactured in Example 3 of the present invention.

[0027] Figure 7This is a graph showing the bonding strength test data of the epoxy resin board-silicone rubber bonded sample in Example 3 of the present invention. Detailed Implementation

[0028] The technical solutions of this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] Firstly, we provide glass fiber reinforced epoxy resin mandrels produced using a traditional thermosetting drawing process. Mandrels produced by this process have a smooth surface and serve as a control example of untreated raw epoxy resin mandrels for subsequent comparative testing with mandrels that have undergone surface roughening treatment. The equipment used in this process includes a yarn frame, impregnation tank, preforming device, thermosetting device, traction machine, and cutting machine. The preparation process is as follows: First, alkali-free glass fiber yarn bundles are installed on the yarn frame. The fiber bundles are gathered by a guide plate and then fully impregnated in an impregnation tank containing epoxy resin. After impregnation, the fiber bundles are initially shaped by a preforming mold and then enter a thermosetting device set at 180 degrees Celsius. Inside the thermosetting device, the epoxy resin undergoes a curing reaction, and the traction machine continuously pulls the pre-cured mandrel from the mold at a speed of 0.5 meters per minute. If necessary, the product can be sent to a curing chamber for further curing and shaping, ultimately forming a glass fiber reinforced epoxy resin mandrel. A typical partial photograph is shown below. Figure 4 As shown in (a) of the diagram.

[0030] Example 1

[0031] This embodiment provides an online sandblasting treatment method, the process diagram of which is shown below. Figure 2 As shown. First, alkali-free glass fiber bundles are fed into the glass fiber inlet. After impregnation, the fiber bundles enter a high-temperature mold (i.e., a thermosetting molding device) for reaction. During the process, the temperature of the high-temperature mold is controlled at 160 degrees Celsius, the speed of the traction machine is maintained at 0.5 meters per minute, and the curing degree of the epoxy resin is maintained between 60% and 80% by adjusting the heating parameters. Subsequently, when the thermoformed mandrel leaves the heating pipe and the surface is not yet completely solidified, it enters an airflow blasting device installed 50 cm after the thermosetting device. Through the combination of airflow and nozzles, alumina powder, which has undergone solid-phase pre-stirring treatment in an ozone atmosphere for 30 minutes, is uniformly sprayed onto the surface of the epoxy resin mandrel; the alumina powder has an average particle size of 100 micrometers. Next, the epoxy resin is completely cured in the curing chamber or the temperature environment of the mandrel itself, and the inorganic powder embedded on the surface of the mandrel is fixed. Finally, the resulting roughened mandrel is continuously pulled out by the traction machine, forming a glass fiber reinforced epoxy resin mandrel with a non-destructive roughened surface.

[0032] Example 2

[0033] This embodiment provides a roughening process for a cooled and molded epoxy resin mandrel, the process diagram of which is shown below. Figure 3 As shown in the image. This process involves coating the surface of a mandrel with a curable adhesive material followed by sandblasting. The specific steps are as follows: First, a cured, smooth-surfaced mandrel with a diameter of 20 mm and a length of 1 meter is loaded into the equipment. Then, the mandrel enters an epoxy coating device, where a 1 mm thick layer of Henkel Loctite E214-HP epoxy resin adhesive is applied to form an adhesive layer. After the adhesive layer has partially cured, the coated mandrel is then sandblasted using an airflow device, spraying silica powder with an average particle size of 30 micrometers that has undergone solid-phase stirring in an ozone atmosphere for 30 minutes. Next, the mandrel enters a heating zone for high-temperature curing of the epoxy adhesive, using hot air at 120 degrees Celsius to permanently fix the silica particles onto the mandrel surface. Finally, a traction machine pulls out the processed mandrel, resulting in a surface-roughened glass fiber reinforced epoxy resin mandrel, as shown in the product photo. Figure 4 As shown in (b) of the diagram.

[0034] To verify the effect of sputtering and fixing silica particles after surface coating, this embodiment of the invention uses an ink marking method for testing. Specifically, a layer of black ink is brushed onto the surface of the epoxy resin mandrel and allowed to stand for 3 minutes. After the excess ink has dried, the mandrel is placed horizontally on a white A4 printing paper on a glass plate, and the markings are recorded. The test results are as follows: Figure 5 As shown, (a) is a photograph of the ink markings on the untreated raw epoxy resin core rod, and (b) is a photograph of the ink markings on the epoxy resin core rod after surface roughening. Because the surface of the untreated raw epoxy resin core rod is smooth, the ink coverage is uniform, leaving large, continuous ink marks on the paper. The core rod treated by the process in Example 2, due to the presence of protruding silica particles on its surface, leaves discontinuous, dotted marks on the paper. This directly demonstrates that the process of this invention successfully roughened the surface of the core rod.

[0035] Example 3

[0036] This embodiment verifies the actual effect of the technology on enhancing interfacial bonding strength through mechanical experiments. An epoxy resin plate was used instead of a mandrel in the experiment. The epoxy resin plate was 100 mm long, 25 mm wide, and 1.6 mm thick. Following the process in Example 2, the experimental group coated the plate surface with a 1 mm thick layer of Henkel Loctite E214-HP epoxy resin adhesive, obtaining several epoxy resin plates with coated surfaces. Then, ozone-pretreated silica powder was sprayed onto the surface of half of the plate samples to create surface-roughened epoxy resin plates. The other half of the plate samples served as a control group, only coated with adhesive without any roughening treatment, and dried at room temperature. 3 grams of silicone rubber compound was placed between two epoxy resin plates and cured for 5 minutes at 170 degrees Celsius and 10 MPa pressure on a plate vulcanizing machine. After holding the pressure and allowing natural cooling, the excess rubber was cut off to obtain the desired product. Figure 6 The experimental samples are shown. Tensile tests were performed on the samples using a universal testing machine (INSTRON 5800) at a speed of 10 mm / min until the epoxy resin board-silicone rubber bonded sample was pulled apart. Typical tensile stress-strain curves for both samples were obtained as follows: Figure 7 As shown in the figure. The results indicate that the pull-out stress of the epoxy resin board-silicone rubber bonded sample after surface roughening treatment reached 4.78 MPa, while the pull-out stress of the untreated original epoxy resin board-silicone rubber bonded sample was only 3.13 MPa, indicating a significant improvement in bond strength.

[0037] In summary, this invention effectively improves the surface roughness of the epoxy resin core rod by fixing pretreated inorganic powder onto the surface, providing mechanical interlocking anchor points for the silicone rubber. This process not only avoids damage to the surface integrity of the core rod caused by mechanical scratching and eliminates the risk of microcracks, but also has strong process compatibility, significantly improving the operational reliability of composite insulators.

[0038] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0039] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator, characterized in that, Includes the following steps: Step 1: Surface pretreatment of inorganic powder; Step 2: The pretreated inorganic powder is fixed onto the surface of the epoxy resin mandrel using a surface roughening process. Step two includes any one of the following process schemes: Option 1: In the epoxy resin mandrel thermosetting drawing process, the epoxy resin mandrel that has left the heating pipe and is in a state of not being fully solidified is sent into an airflow sandblasting device. The inorganic powder is sprayed and embedded into the surface of the epoxy resin mandrel by the airflow pressure. As the epoxy resin mandrel cools and solidifies, the inorganic powder is fixed. Option 2: Coat the surface of the cooled and molded epoxy resin mandrel with epoxy resin adhesive to form an adhesive layer, spray the inorganic powder onto the adhesive layer, and then heat-cure the epoxy resin adhesive to fix the inorganic powder.

2. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1, characterized in that, The technical means for surface pretreatment of inorganic powder in step one are one or more of the following: plasma treatment, solid-phase stirring treatment in ozone atmosphere, nitric acid immersion treatment, concentrated sulfuric acid immersion treatment with a concentration greater than 90%, and hydrogen peroxide immersion treatment.

3. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1 or 2, characterized in that, The inorganic powder is one of the following: silicon dioxide particles, wollastonite particles, silicate particles, alumina particles, aluminum nitride particles, and silicon carbide particles.

4. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1 or 2, characterized in that, The inorganic powder is a combination of several particles selected from silicon dioxide particles, wollastonite particles, silicate particles, alumina particles, aluminum nitride particles, and silicon carbide particles.

5. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1, characterized in that, The inorganic powder coating density on the surface of the epoxy resin mandrel is from 40 particles per square centimeter to 60,000 particles per square centimeter.

6. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1, characterized in that, After step two is completed, the process also includes applying a silicone rubber adhesive to the roughened surface of the epoxy resin mandrel.

7. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 1, characterized in that, After step two is completed, the process also includes applying a special interface modifier for composite insulator core rods to the roughened epoxy resin core rod surface.

8. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 3, characterized in that, The particle size of the inorganic powder is from 1 micrometer to 100 micrometers.

9. The non-destructive roughening process for the surface of an epoxy resin core rod of a composite insulator according to claim 4, characterized in that, The particle size of the inorganic powder is from 1 micrometer to 100 micrometers.

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