A manufacturing method of a pre-coated DC post insulator

Abstract

The application discloses a kind of based on pre-coating DC basin type insulator manufacturing method, including‌Mold is placed in oven, preheating is carried out at preset temperature;Coating is added to feed system;Preheated mold is transferred to coating platform, and the starting position and posture of mechanical arm automatic calibration spray head are ensured that spray head and mold surface distance constant and vertical;Spray head moves along the inner surface of mold according to predetermined trajectory, and spray head is uniformly sprayed to the mold surface with coating, while spraying cooling airflow to the wet coating area just sprayed, so that the coating temperature of the area rapidly reduces;Make the whole inner surface that needs to be coated is uniformly covered with a layer of pre-coating with consistent thickness;‌The mold that has completed pre-coating is rapidly transferred to vacuum pouring box, and vacuumizing program is started, and the main body material of basin type insulator is poured into the mold.The application realizes the industrial application of coating technology in DC insulating parts, and greatly improves the DC insulation performance of insulating parts.

Description

Technical Field

[0001] This invention relates to the field of high-voltage direct current (HVDC) transmission equipment manufacturing technology, and more specifically to a method for manufacturing DC basin insulators based on pre-coating. Background Technology

[0002] In high-voltage direct current (HVDC) transmission systems, basin insulators, as core insulating components in gas-insulated switchgear (GIS), are crucial for long-term operational reliability. Compared to alternating current (AC) electric fields, under DC voltage, charge migration and accumulation are more likely to occur on or inside the basin insulator, forming space charge. This leads to severe distortion of the local electric field, easily triggering partial discharge or surface flashover. Simultaneously, stable leakage current and the resulting Joule heating can also cause localized overheating and aging of the material. To address this challenge, coating the surface of basin insulators with functional coatings (such as coatings with controllable conductivity or nonlinear resistance characteristics) has become a recognized effective technical approach. This aims to provide a controllable discharge channel for surface charges, homogenize the electric field distribution, and improve DC insulation performance.

[0003] Currently, the industry generally adopts a post-coating process, which involves spraying and curing the surface of the insulator after the substrate has been fully formed and cured. Although existing patents (such as CN113171955B, a coating curing device for basin-type insulators, and CN119525061A, a spraying device and method for basin-type insulators) have optimized the spraying and curing equipment, and other patents (such as CN118888230B, a nonlinear material gradient coating method for improving surface flashover of insulators) focus on improving the coating material formulation, these existing technical solutions have not fundamentally solved the two major bottlenecks restricting the industrialization of this technology:

[0004] First, there is the issue of interface bonding. The post-coating process forms a coating on the cured insulator substrate, inevitably creating a physical or chemical interface between the coating and the substrate. This interface is prone to internal stress and microscopic defects due to mismatches in the materials' coefficients of thermal expansion and curing shrinkage, leading to insufficient bonding strength between the coating and the substrate. Under long-term electrical, thermal, and mechanical stress, these interface defects can develop, potentially causing the coating to crack, wrinkle, or even peel off, becoming a potential hazard for insulation failure.

[0005] Secondly, there is the issue of coating uniformity. Basin-type insulators have a complex three-dimensional curved surface structure. During the post-coating process, the coating is prone to flowing or accumulating due to gravity and spraying parameters, resulting in uneven final coating thickness. Uneven thickness directly affects the uniformity and consistency of the coating's electric field modulation function, and is a significant reason for unstable product quality.

[0006] Therefore, a completely new manufacturing method is urgently needed to fundamentally solve the problems of poor bonding between the coating and the substrate and uneven coating thickness, so as to promote the industrial application of surface coating technology in the field of DC basin insulators. Summary of the Invention

[0007] In view of this, the present invention provides a method for manufacturing DC basin insulators based on pre-coating, which solves the problems of insufficient interfacial bonding strength between the coating and the basin insulator substrate due to the step-by-step curing process, long-term instability, and uneven coating thickness caused by paint flow during spraying in the post-coating process.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for manufacturing DC basin-type insulators based on pre-coating includes the following steps: S1. Mold preheating: Place the basin-type insulator forming mold in an oven and preheat it at a preset temperature; S2. Paint loading: Add the prepared paint to the feeding system of the spraying equipment; S3. Mold Positioning and Nozzle Calibration: Transfer the preheated mold to the coating platform in the cleanroom and fix it. Start the spraying system. The robotic arm automatically calibrates the starting position and posture of the nozzle to ensure that the distance between the nozzle and the mold surface is constant and perpendicular. S4. Spraying and Cooling: The robotic arm drives the nozzle to move along the inner surface of the mold according to a predetermined trajectory. The nozzle sprays the paint evenly onto the surface of the mold and simultaneously sprays cooling airflow into the area of ​​the freshly sprayed wet paint, causing the paint temperature in that area to drop rapidly. S5. Complete mold pre-coating: Repeat step S4 until the entire inner surface of the mold that needs to be coated is evenly covered with a pre-coating layer of uniform thickness. S6. Vacuum casting: Quickly transfer the pre-coated mold to the vacuum casting box, start the vacuuming process, and pour the pot insulator main body material into the mold.

[0009] Preferably, in step S1, dust adhering to the mold is removed before the mold enters the oven.

[0010] Preferably, the mold preset time is no less than 8 hours.

[0011] Preferably, in step S2, the coating uses the same epoxy resin material as the main body of the basin insulator.

[0012] Preferably, in step S3, the control system of the spraying system pre-imports the mold structure dimensions, and the robotic arm controls the distance between the nozzle and the mold surface to remain constant based on the pre-imported three-dimensional structure data of the inner surface of the mold, and keeps the spraying direction of the nozzle perpendicular to the tangent direction of the mold surface at the location of the nozzle.

[0013] Preferably, the nozzle has two spray ports, wherein the first spray port is connected to the outlet of the feeding system, and the second spray port is connected to the outlet of the air cooler to achieve simultaneous spraying and cooling.

[0014] Preferably, the first injection port is located at the front end of the nozzle's moving trajectory.

[0015] Preferred options also include: S7. Curing and Demolding: Transfer the cast mold to an oven and cure it at high temperature according to the set curing temperature curve, so that the pre-coating layer and the main material are cured into a structural whole. After curing, allow the mold to cool and demold.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for manufacturing DC basin insulators based on pre-coating, which has the following beneficial effects: 1. Completely solve the interface problem: By using the same epoxy resin material as the main material of the basin insulator to make the coating and achieving synchronous curing of the pre-coating and the main material, the two are chemically cross-linked at the molecular level to form a whole, completely eliminating the physical / chemical interface inherent in the traditional post-coating process. This fundamentally eliminates the risk of failure such as coating peeling and cracking caused by interface defects, and greatly improves the long-term operational reliability of the product.

[0017] 2. Ensure coating uniformity: By combining mold preheating to promote gelation with instant air cooling for thickening, and using vertical constant-distance intelligent spraying equipment, the flow of coating on complex curved surfaces is effectively suppressed, achieving precise and uniform control of coating thickness and ensuring consistent product performance.

[0018] 3. Promoting Industrial Application: This method systematically solves the core obstacles restricting the industrialization of surface coating technology, and provides a stable, reliable and highly repeatable manufacturing solution, laying the technical foundation for the large-scale production of high-performance DC basin insulators. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 Manufacturing flow chart provided for this invention; Figure 2 This is a schematic diagram of the nozzle movement trajectory provided by the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Whether the surface coating of a basin-type insulator is sprayed or adhered by oscillating flow, the coating process is carried out after the basin-type insulator body is formed. This inevitably creates an interface between the coating and the basin-type insulator substrate material. Interface defects and long-term instability are largely unresolved by technical means, a major reason why the industrial manufacturing of coated basin-type insulators cannot be implemented. Furthermore, during the coating process, the paint flow leads to uneven coating thickness, another significant reason why coating technology cannot be industrialized. Therefore, this invention discloses a pre-coated DC basin-type insulator manufacturing method, fundamentally solving the problem of the inability to industrialize coating technology, realizing the industrial application of coating technology in DC insulating components, and significantly improving the DC insulation performance of the insulators.

[0023] A method for manufacturing a DC basin-type insulator based on pre-coating according to an embodiment of the present invention includes the following steps: S1. Mold Preheating: Clean the mold for forming the basin insulator, remove the dust adhering to its surface, place the cleaned mold in an oven, and preheat it at a preset temperature. The preset temperature is set according to the characteristics of the epoxy resin material, and the preset time of the mold is not less than 8 hours.

[0024] S2. Coating Filling: Add the prepared coating to the feeding system of the spraying equipment. The epoxy resin material used in the coating is exactly the same as the epoxy resin material used for casting the main body of the pot insulator in the subsequent steps.

[0025] The spraying equipment includes a robotic arm for driving the spray head to move along a preset trajectory; the spray head, located at the drive end of the robotic arm, has two spray nozzles, wherein the first spray nozzle is connected to the discharge port of the feeding system, and the second spray nozzle is connected to the air outlet of the cooling fan to simultaneously achieve spraying and cooling, and the first spray nozzle is located at the front end of the spray head's moving trajectory; the motion control system is pre-loaded with the mold structure dimensions and is configured to control the robotic arm to maintain a constant distance between the spray head and the surface to be sprayed on the mold during movement, based on the pre-loaded three-dimensional structural data of the inner surface of the mold, and to ensure that the spraying direction of the spray head is always perpendicular to the tangent direction of the mold surface at the location of the spray head.

[0026] S3. Mold Positioning and Nozzle Calibration: Transfer the preheated mold to the coating platform in the cleanroom and fix it. Start the spraying system. The robotic arm automatically calibrates the starting position and posture of the nozzle according to the preset 3D model data of the mold, ensuring that the distance between the nozzle and the mold surface is constant and perpendicular.

[0027] S4. Spraying and Cooling: Start the spraying program. The robotic arm drives the nozzle to move along the inner surface of the mold along a predetermined trajectory. The first spray nozzle in front of the nozzle sprays the paint evenly onto the surface of the high-temperature mold. The moment the paint comes into contact with the high-temperature mold, the resin components react rapidly and begin to gel initially. At the same time, the second spray nozzle sprays cooling airflow at the area of ​​the freshly sprayed wet paint, which rapidly reduces the temperature of the paint in that area, causes the viscosity to rise sharply, and effectively curbs the flow trend.

[0028] S5. Complete mold pre-coating: Repeat step S4 until the entire inner surface of the mold that needs to be coated is uniformly covered with a pre-coating layer of consistent thickness.

[0029] S6. Vacuum casting: Quickly transfer the pre-coated mold to the vacuum casting box, start the vacuuming process, and pour the pot insulator main body material into the mold.

[0030] S7. Curing and Demolding: Transfer the cast mold to an oven and cure it at high temperature according to the set curing temperature curve (heating, holding, cooling). During this process, the pre-coating on the surface of the mold and the epoxy resin in the main material poured inside undergo cross-linking reaction simultaneously, and finally cure into a whole structure. After the curing process is completed, wait for the mold to cool to a suitable temperature and then demold to obtain the finished DC basin insulator with integrated high-performance surface coating.

[0031] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for manufacturing DC basin-type insulators based on pre-coating, characterized in that, Includes the following steps: S1. Mold preheating: Place the basin-type insulator forming mold in an oven and preheat it at a preset temperature; S2. Paint loading: Add the prepared paint to the feeding system of the spraying equipment; S3. Mold Positioning and Nozzle Calibration: Transfer the preheated mold to the coating platform in the cleanroom and fix it. Start the spraying system. The robotic arm automatically calibrates the starting position and posture of the nozzle to ensure that the distance between the nozzle and the mold surface is constant and perpendicular. S4. Spraying and Cooling: The robotic arm drives the nozzle to move along the inner surface of the mold according to a predetermined trajectory. The nozzle sprays the paint evenly onto the surface of the mold and simultaneously sprays cooling airflow into the area of ​​the freshly sprayed wet paint, causing the paint temperature in that area to drop rapidly. S5. Complete mold pre-coating: Repeat step S4 until the entire inner surface of the mold that needs to be coated is evenly covered with a pre-coating layer of uniform thickness. S6. Vacuum casting: Quickly transfer the pre-coated mold to the vacuum casting box, start the vacuuming process, and pour the pot insulator main body material into the mold.

2. The method for manufacturing a DC basin-type insulator based on pre-coating according to claim 1, characterized in that, In step S1, dust adhering to the mold is removed before the mold enters the oven.

3. The method for manufacturing a DC basin-type insulator based on pre-coating according to claim 2, characterized in that, The mold preset time is no less than 8 hours.

4. The method for manufacturing a DC basin-type insulator based on pre-coating according to claim 1, characterized in that, In step S2, the coating uses the same epoxy resin material as the main body of the basin insulator.

5. The method for manufacturing a DC basin-type insulator based on pre-coating according to claim 1, characterized in that, In step S3, the control system of the spraying system pre-imports the mold structure dimensions. Based on the pre-imported three-dimensional structure data of the inner surface of the mold, the robotic arm controls the distance between the nozzle and the mold surface to remain constant, and ensures that the spraying direction of the nozzle is always perpendicular to the tangent direction of the mold surface at the location of the nozzle.

6. The method for manufacturing a DC basin-type insulator based on pre-coating according to claim 1, characterized in that, The nozzle has two spray ports, wherein the first spray port is connected to the outlet of the feeding system and the second spray port is connected to the outlet of the air cooler to achieve spraying and cooling simultaneously.

7. A method for manufacturing a DC basin-type insulator based on pre-coating according to claim 6, characterized in that, The first injection port is located at the front end of the nozzle's moving trajectory.

8. A method for manufacturing a DC basin-type insulator based on pre-coating according to claim 1, characterized in that, Also includes: S7. Curing and Demolding: Transfer the cast mold to an oven and cure it at high temperature according to the set curing temperature curve, so that the pre-coating layer and the main material are cured into a structural whole. After curing, allow the mold to cool and demold.

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