Radian control hot press molding method for arc-shaped plate of insulating ring of generator

Abstract

The invention relates to a radian control hot press molding method for an arc-shaped plate of an insulating ring of a generator. The method comprises the following steps: S1, establishing a digital reference; s2, preparing a mold; s3, blank preparation and die filling; s4, performing real-time data acquisition and cooperative control; and S5, curing and forming. The method has the following advantages that by coordinating the flow choking and guiding functions of the blank and the multi-unit collaborative segmented pressurizing procedure, glue solution overflow is effectively restrained, and the radian forming precision of the arc-shaped plate is improved.

Description

Technical Field

[0001] This invention belongs to the field of advanced manufacturing technology for key components of new energy power generation equipment, specifically relating to a hot pressing forming method for controlling the arc of an arc-shaped insulating ring plate for a generator. Background Technology

[0002] The arc-shaped insulating ring plate of a generator is a crucial insulating component in large-scale power generation equipment. The precision of its curvature directly affects the assembly accuracy and operational reliability of the motor. New energy equipment such as wind power, hydrogen energy, and nuclear power place higher demands on the lightweight, high precision, and long lifespan of insulating components. Currently, this component is typically manufactured using a single pre-impregnated glass fiber cloth laminate structure through hot pressing. The design of a single flow-blocking layer is insufficient, leading to excessive resin flow during hot pressing and a high risk of overflow. Conversely, excessive flow restriction results in uneven interlayer wetting, forming dry spots or voids, severely impacting the product's insulation performance and mechanical strength.

[0003] To address the aforementioned technical challenges, a method has been proposed that involves layering fiberglass boards and epoxy fiberglass mats before hot-pressing. However, due to differences in the coefficients of thermal expansion and resin shrinkage rates between the fiberglass boards and epoxy fiberglass mats, uneven internal stress and deformation can occur between the layers under the thermo-mechanical coupling environment of hot pressing. Traditional molds can only provide overall vertical pressure and cannot compensate for or correct this uneven deformation in real time. This results in large curvature deviations, uneven edge warping, and low product consistency and dimensional accuracy of the formed curved plate. Furthermore, resin overflow is prone to occur during hot pressing, leading to material waste and uneven resin distribution in localized areas, which in turn affects the accurate forming of the curvature and surface quality. Therefore, effectively suppressing resin overflow and achieving precise curvature control during the molding process has become a key technical challenge for improving the manufacturing quality of generator insulation ring curved plates. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a hot pressing method for controlling the curvature of an arc plate for generator insulation rings. By coordinating the flow obstruction and flow guidance functions of the blank and the multi-unit collaborative segmented pressing process, the overflow of adhesive is effectively suppressed and the curvature forming accuracy of the arc plate is improved.

[0005] The objective of this invention is achieved through the following technical solution: a method for hot-pressing and forming an arc-shaped insulating ring plate for generators, comprising the following steps: S1. Establish digital benchmark: Produce a theoretical three-dimensional digital model of the arc plate according to the design requirements of the insulating ring, and set the target value of the arc and the allowable tolerance range; S2. Mold preparation: Positioning a mold that matches the theoretical three-dimensional digital model. The mold includes a main pressure execution unit for hot pressing the arc plate and a radial pressure execution unit for correcting the curvature of the arc plate. It also includes a temperature control system integration unit, a sensor system integration unit, and a central controller. S3. Blank preparation and mold loading: The blank is made of multiple layers of glass fiber board and multiple layers of epoxy glass fiber mat board laid alternately. Glass fiber board is laid as a flow-blocking layer in the outermost layer, the middle layer and the uppermost layer. Epoxy glass fiber mat board is laid between the upper and middle layers and between the lower and middle layers as a flow-guiding and reaction layer. The blank is placed into the mold, the mold is closed and the segmented pressurization program optimized based on finite element hot pressing simulation is set as the initial process parameters. S4. Real-time data acquisition and collaborative control: The hot pressing process is initiated. Through the main pressure execution unit, radial pressure execution unit, sensor system integration unit, and temperature control system integration unit, real-time data is acquired and overall pressure and heat are applied according to the segmented pressurization process. The segmented pressurization process includes the initial compaction stage for initially removing interlayer air and stabilizing the position of the blank, the first preheating and pressurization stage for overall uniform compaction, the low viscosity heat preservation stage for suppressing resin overflow, the gelation and full-pressure shaping stage, and the arc shaping and cooling stage. Each unit coordinates and controls each other to simultaneously suppress resin overflow and control the arc correction during the hot pressing process of the blank. S5. Curing and molding: After the curvature deviation stabilizes within the allowable tolerance range and the preset curing time is reached, the mold is opened and the molded curved plate is taken out after cooling.

[0006] A further improvement of the present invention is that step S4 specifically includes the following steps: S41. Initial Compaction Stage: After the mold closes and reaches 90°C, the main pressure actuator applies an overall pressure of 0.2-0.5 MPa to the billet, while the radial pressure actuator simultaneously applies an initial local pressure of 0.1-0.3 MPa to initially remove interlayer air and stabilize the billet position. The sensor system integration unit collects edge position data of the curved plate at a frequency of not less than 10Hz. The central controller calculates the initial curvature deviation. If the deviation exceeds the set threshold, the radial pressure actuator is activated for fine-tuning, with the adjustment range not exceeding 20% ​​of the initial pressure. S42, First preheating and pressurization stage: The temperature control system integrated unit monitors the mold temperature in real time. During this stage, the mold temperature is controlled at 90-120℃. The main pressure execution unit increases the pressure to 0.8–1.2 MPa, and the radial pressure execution unit simultaneously increases the pressure to the same level to achieve uniform compaction. S43, Low viscosity heat preservation stage: During this stage, the mold temperature is controlled at 120-140℃. The main pressure actuator maintains or slightly reduces the pressure to 0.6–1.0 MPa to suppress resin overflow. The radial pressure actuator independently adjusts the pressure according to the real-time curvature deviation, with an adjustment range of 0.5–1.5 MPa and a response time of no more than 0.5 seconds, ensuring that the curvature deviation is controlled within ±0.1 mm. S44, Gelation and Full Pressure Shaping Stage: The central controller determines the gel point based on the dielectric sensor signal from the integrated sensing unit and triggers the main pressure actuator to rapidly apply a full pressure of 0.5–1.0 MPa; the radial pressure actuator synchronously applies the same full pressure as the main pressure actuator and maintains position lock in the final stage to prevent rebound; S45, Cooling Stage: The main pressure actuator switches to position control mode to maintain the mold closed position constant to compensate for the deformation caused by material cooling and shrinkage; the radial pressure actuator makes fine adjustments according to the curvature change caused by cooling and shrinkage, with the pressure adjustment not exceeding 0.2 MPa, to ensure that the final curvature meets the design requirements.

[0007] A further improvement of the present invention is that the radial pressure actuation unit includes multiple servo electric cylinders and multiple pressure heads. The cylinder body of the servo electric cylinder is fixed in a preset mounting cavity inside the mold body. The drive end of each servo electric cylinder is connected to the pressure head. The multiple pressure heads are distributed along the arc direction of the blank end. There is a composite pressure foot structure between the multiple pressure heads and the blank to ensure the smoothness of the arc.

[0008] A further improvement of the present invention is that the composite pressure foot structure includes a rigid distribution plate, a flexible homogenization layer, and several ball joint connecting rods. The working surface shape of the rigid distribution plate matches the target outline of the arc plate; The flexible homogenization layer is fixedly attached to the working surface of the rigid distribution plate; One end of the ball joint connecting rod is connected to the corresponding pressure head, and the other end is connected to the back of the rigid distribution plate; The radial pressure actuation unit drives the composite pressure foot structure to convert the concentrated thrust of the pressure head into a uniformly distributed surface pressure that acts on the blank, thereby avoiding local indentations and ensuring a smooth curvature.

[0009] A further improvement of the present invention is that: the sensing system integration unit includes Multiple non-contact displacement sensors are evenly distributed along the curvature of the blank inside the mold body to monitor the positional changes of the edge of the arc plate in real time during the forming process. Multiple dielectric sensors are disposed on the end face of the rigid distribution plate in contact with the blank. By measuring the dielectric properties of the resin under an alternating electric field, the gelation and curing state of the resin can be reflected in real time. Multiple temperature sensors are installed inside the mold body to monitor the temperature of the mold cavity in real time. A contact position sensor is mounted on the main pressure actuator unit to measure the displacement of the main pressure actuator unit; Multiple force sensors are integrated between the pressure head and the servo electric cylinder to provide real-time feedback on the radial pressure applied to the billet.

[0010] A further improvement of the present invention is that the number of multiple servo electric cylinders corresponds to the number of multiple non-contact displacement sensors and their positions are related, so that at least one servo electric cylinder is responsible for the curvature compensation adjustment of the area monitored by each non-contact displacement sensor.

[0011] A further improvement of the present invention is that the non-contact displacement sensor is a laser displacement sensor or a spectral confocal sensor, with a sampling frequency of not less than 10 Hz, and the number of such sensors installed is not less than four, and they are evenly distributed along the edge of the arc plate.

[0012] A further improvement of the present invention is that the main pressure execution unit includes a main pressure cylinder and a servo driver that is communicatively connected to a central controller. The central controller sends instructions to the servo driver to control the main pressure cylinder to apply overall pressure according to the segmented pressurization process. The temperature control system integration unit includes a heating subsystem, a cooling subsystem, and a temperature controller. The central controller sends instructions to the heating subsystem and the cooling subsystem according to the target temperature. The temperature controller receives the target temperature instruction from the central controller and feeds back the current temperature, operating status, and fault information to the central controller.

[0013] A further improvement of the present invention is that the preparation of the glass fiber board and the epoxy glass fiber mat board includes, by weight, selecting 100-120 parts of bisphenol A epoxy resin, 50-60 parts of silica powder, 6-10 parts of dicyandiamide and 3-4 parts of accelerator, stirring at 60-80°C for 20-30 minutes, then adding 3-4 parts of fumed silica, and grinding to prepare an adhesive solution; cutting the glass fiber cloth and epoxy glass fiber mat according to the arc size of the arc board and impregnating them with the adhesive solution, and then performing vacuum impregnation and curing treatment to form a rigid board structure.

[0014] A further improvement of the present invention is that the glass fiber board has a single layer thickness of 0.2 mm, and the epoxy glass fiber mat board has a single layer thickness of 0.5 mm.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The blank in this invention employs a structure with multiple layers of glass fiber boards and epoxy glass fiber mats laid alternately, which offers significant advantages in controlling curvature and suppressing adhesive overflow. The glass fiber boards, acting as flow-blocking layers in the outermost and middle layers, effectively limit excessive resin flow during hot pressing, preventing fiber / resin imbalance and localized resin deficiency caused by excessive resin escape, thereby reducing curvature distortion due to uneven resin distribution. The epoxy glass fiber mat, acting as a flow-guiding and reaction layer concentrated in the middle region, ensures uniform resin distribution and full curing through its excellent wettability and reactivity, improving the overall density and shape stability of the material. This structural design, by coordinating the "flow-blocking" and "flow-guiding" functions, effectively suppresses adhesive overflow while ensuring relatively consistent shrinkage behavior of each layer during heat deformation, providing a material basis for high-precision curvature forming.

[0016] 2. Through the coordinated operation of the main pressure actuator, radial pressure actuator, sensor system integration unit, and temperature control system integration unit, combined with the segmented pressurization process, high-precision closed-loop control of the hot pressing process is achieved. Regarding curvature control, the segmented pressurization process applies differentiated pressure according to the material state at different stages: in the initial stage, low pressure is used to remove interlayer air and initially stabilize the blank; in the low-viscosity heat preservation stage, an independently controlled radial pressure unit compensates in real time for curvature deviations caused by differences in material thermal behavior, ensuring that curvature accuracy is always controlled within ±0.1 mm; after gel point identification, full pressure is quickly applied and the position is locked to effectively suppress rebound; in the cooling stage, position control mode compensates for shrinkage deformation, ensuring that the final curvature meets design requirements. Regarding suppressing resin overflow, the system appropriately reduces the main pressure and independently adjusts the radial pressure during the low-viscosity resin stage, avoiding excessive resin extrusion due to excessive pressure, and precisely controlling the curvature to prevent localized resin enrichment and overflow caused by uneven deformation. The control architecture, which combines real-time feedback from multiple sensors with coordinated response from multiple actuators, enables precise decoupling and control of the coupling of multiple parameters, including temperature, pressure, curvature, and curing state, thereby simultaneously improving the accuracy of curvature molding and the stability of resin behavior. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the overall process flow of the present invention.

[0018] Figure 2 This is a schematic diagram of the mold for the present invention.

[0019] Figure 3 This is a schematic diagram of the radial pressure actuator.

[0020] Figure 4 This is a schematic diagram of the billet laying process.

[0021] Figure 5This is a graph showing the changes in pressure and temperature over time during the segmented pressurization process of this invention.

[0022] The numbers in the diagram are: 1-Main pressure actuator, 2-Radial pressure actuator, 3-Temperature control system integration unit, 4-Sensing system integration unit, 5-Central controller, 6-Burnt material; 21-Servo electric cylinder, 22-Pressure head, 23-Composite pressure foot structure, 231-Rigid distribution plate, 232-Flexible homogenization layer, 233-Spherical hinge connecting rod; 41-Non-contact displacement sensor, 42-Dielectric sensor, 43-Temperature sensor, 44-Contact displacement sensor, 45-Force sensor; 61-Glass fiberboard, 62-Epoxy glass fiber mat board. Detailed Implementation

[0023] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the structure or unit referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0025] A method for hot-pressing and controlling the curvature of an arc-shaped insulating ring plate for a generator, referring to... Figure 1 This includes the following steps: S1. Establish digital benchmark: Produce a theoretical three-dimensional digital model of the arc plate according to the design requirements of the insulating ring, and set the target value of the arc and the allowable tolerance range; S2. Mold Preparation: Refer to... Figure 2 The mold is positioned to match the theoretical three-dimensional digital model. The mold includes a main pressure execution unit 1 for hot pressing the arc plate and a radial pressure execution unit 2 for correcting the curvature of the arc plate. It also includes a temperature control system integration unit 3, a sensing system integration unit 4, and a central controller 5. S3. Blank preparation and mold assembly: Refer to... Figure 4 The blank 6 is made of multiple layers of glass fiber board 61 and multiple layers of epoxy glass fiber mat board 62 laid alternately. Glass fiber board 61 is laid in the outermost layer, the middle layer and the uppermost layer as flow-blocking layer. Epoxy glass fiber mat board 62 is laid between the upper layer and the middle layer and between the lower layer and the middle layer as flow-guiding and reaction layer. The blank 6 is placed in the mold, the mold is closed and the segmented pressurization program optimized based on finite element hot pressing simulation is set as the initial process parameters. S4. Real-time data acquisition and collaborative control: The hot pressing process is initiated. Through the main pressure execution unit 1, radial pressure execution unit 2, sensor system integration unit 4, and temperature control system integration unit 3, real-time data is acquired and overall pressure and heat are applied according to the segmented pressurization process. The segmented pressurization process includes the initial compaction stage for initially removing interlayer air and stabilizing the position of the blank, the first preheating and pressurization stage for overall uniform compaction, the low viscosity heat preservation stage for suppressing resin overflow, the gelation and full-pressure shaping stage, and the arc shaping and cooling stage. Each unit coordinates and controls each other to simultaneously suppress resin overflow and control the arc correction during the hot pressing process of the blank. S5. Curing and molding: After the curvature deviation stabilizes within the allowable tolerance range and the preset curing time is reached, the mold is opened and the molded curved plate is taken out after cooling.

[0026] In this invention, the blank employs a structure with multiple layers of glass fiber boards 61 and epoxy glass fiber mat boards 62 laid alternately, which offers significant advantages in controlling curvature and suppressing adhesive overflow. The glass fiber boards 61, acting as flow-blocking layers, are arranged in the outermost and middle layers, effectively limiting excessive resin flow during hot pressing. This avoids fiber / resin imbalance and localized resin deficiency caused by excessive resin escape, thereby reducing curvature distortion caused by uneven resin distribution. The epoxy glass fiber mat boards, acting as flow-guiding and reaction layers concentrated in the middle region, ensure uniform resin distribution and full curing through their excellent wettability and reactivity, improving the overall density and shape stability of the material. This structural design, by coordinating the "flow-blocking" and "flow-guiding" functions, effectively suppresses adhesive overflow while ensuring relatively consistent shrinkage behavior of each layer during heat deformation, providing a material basis for high-precision curvature forming.

[0027] Based on this embodiment, step S4 specifically includes the following steps: S41, Initial Compaction Stage: After the mold closes and reaches 90°C, the main pressure actuator 1 applies an overall pressure of 0.2-0.5 MPa to the billet, while the radial pressure actuator 2 simultaneously applies an initial local pressure of 0.1-0.3 MPa to initially remove interlayer air and stabilize the billet position. The sensor system integration unit 4 collects the edge position data of the curved plate at a frequency of not less than 10 Hz, and the central controller 5 calculates the initial curvature deviation. If the deviation exceeds the set threshold, the radial pressure actuator 2 is activated for fine-tuning, with the adjustment range not exceeding 20% ​​of the initial pressure. S42, First preheating and pressurization stage: Temperature control system integrated unit 3 monitors the temperature inside the mold in real time. During this stage, the temperature inside the mold is controlled at 90-120℃. The main pressure execution unit 1 increases the pressure to 0.8-1.2 MPa, and the radial pressure execution unit 2 simultaneously increases the pressure to the same level to achieve uniform compaction. S43, Low viscosity heat preservation stage: During this stage, the mold temperature is controlled at 120-140℃. The main pressure actuator 1 maintains or slightly reduces the pressure to 0.6–1.0 MPa to suppress resin overflow. The radial pressure actuator 2 independently adjusts the pressure according to the real-time curvature deviation, with an adjustment range of 0.5–1.5 MPa and a response time of no more than 0.5 seconds, ensuring that the curvature deviation is controlled within ±0.1 mm. S44, Gelation and Full Pressure Shaping Stage: The central controller 5 determines the gel point based on the signal from the dielectric sensor 42 in the sensing system integration unit 4, and triggers the main pressure execution unit 1 to quickly apply a full pressure of 0.5–1.0 MPa; the radial pressure execution unit 2 synchronously applies the same full pressure as the main pressure execution unit 1, and maintains position lock in the final stage to prevent rebound; S45, Cooling Stage: The main pressure actuator 1 switches to position control mode to maintain the mold closed position constant to compensate for the deformation caused by material cooling and shrinkage; the radial pressure actuator 2 makes fine adjustments according to the curvature change caused by cooling and shrinkage, with the pressure adjustment amount not exceeding 0.2 MPa, to ensure that the final curvature meets the design requirements.

[0028] Reference Figure 5 The pressure and temperature change curves shown in the segmented pressurization process are analyzed as follows: As the hot pressing process transitions from the initial compaction stage to the first preheating and pressurization stage, the main pressure and radial pressure are increased synchronously and slowly (from 0.2–0.5 MPa to 0.8–1.2 MPa), while the temperature rises from room temperature to 90–120°C. This coordinated increase in pressure and temperature during this stage aims to initially eliminate interlayer air and achieve uniform compaction of the entire billet, establishing the basic material conditions for curvature control. Upon entering the low-viscosity holding stage (120–140°C), the main pressure is slightly reduced to 0.6–1.0 MPa to suppress resin overflow, while the radial pressure is independently controlled between 0.5–1.5 MPa, with a response time not exceeding 0.5 seconds. This stage is a critical window for curvature control: the reduction in main pressure effectively reduces the risk of resin extrusion, while the rapid and independent adjustment of radial pressure compensates in real time for localized deformation caused by differences in material thermal behavior, ensuring that the curvature deviation is always controlled within ±0.1 mm.

[0029] When the system determines that the resin has reached its gel point based on the dielectric sensor signal, it quickly enters the gelation and full-pressure shaping stage. The main pressure and radial pressure are simultaneously applied at a full pressure of 0.5–1.0 MPa and locked in position to effectively suppress springback and achieve stable shaping of the arc. Finally, during the cooling stage, the main pressure switches to position control mode to compensate for material shrinkage, and the radial pressure is fine-tuned (≤0.2 MPa) to ensure that the final arc accuracy meets design requirements.

[0030] As can be seen, this segmented pressurization curve achieves decoupled optimization of "temperature-pressure-curvature-curing state" through multi-parameter synergistic control: the low viscosity stage is the optimal window for curvature control, at which point the main pressure is reduced to suppress overflow, and the radial pressure is independently adjusted to compensate for deformation; the two work together to achieve the ultimate curvature accuracy. The curve clearly shows that, prioritizing curvature accuracy and resin behavior control, the parameter matching during the low viscosity holding stage (temperature 120–140℃, main pressure 0.6–1.0 MPa, radial pressure 0.5–1.5 MPa) is the optimal range for the molding process. Considering the overall molding efficiency and material stability requirements, the hot pressing process should be maintained for at least 10–15 minutes in this stage to ensure sufficient synergy between curvature correction and resin curing.

[0031] Through the coordinated operation of the main pressure actuator 1, radial pressure actuator 2, sensing system integration unit 4, and temperature control system integration unit 3, combined with the segmented pressurization process, high-precision closed-loop control of the hot pressing process is achieved. Regarding curvature control, the segmented pressurization process applies differentiated pressure according to the material state at different stages: in the initial stage, low pressure is used to remove interlayer air and initially stabilize the blank 6; in the low-viscosity heat preservation stage, the independently controlled radial pressure unit 2 compensates in real time for curvature deviations caused by differences in material thermal behavior, ensuring that curvature accuracy is always controlled within ±0.1 mm; after gel point identification, full pressure is quickly applied and the position is locked to effectively suppress rebound; in the cooling stage, position control mode compensates for shrinkage deformation, ensuring that the final curvature meets design requirements. Regarding suppressing resin overflow, the system appropriately reduces the main pressure and independently adjusts the radial pressure during the low-viscosity resin stage, avoiding excessive resin extrusion due to excessive pressure, and precisely controlling the curvature to prevent localized resin enrichment and overflow caused by uneven deformation. The control architecture, which combines real-time feedback from multiple sensors with coordinated response from multiple actuators, enables precise decoupling and control of the coupling of multiple parameters, including temperature, pressure, curvature, and curing state, thereby simultaneously improving the accuracy of curvature molding and the stability of resin behavior.

[0032] Specifically, refer to Figure 3 The radial pressure actuation unit 2 includes multiple servo electric cylinders 21 and multiple pressure heads 22. The cylinder body of the servo electric cylinder 21 is fixed in a preset mounting cavity inside the mold body. The drive end of each servo electric cylinder 21 is connected to the pressure head 22. The multiple pressure heads 22 are distributed along the arc direction of the end of the blank 6. There is a composite pressure foot structure 23 between the multiple pressure heads 22 and the blank 6 to ensure the smoothness of the arc.

[0033] Traditional molds, during hot pressing, can only provide overall pressure in the vertical direction and cannot compensate for curvature deviations caused by differences in material thermal expansion coefficients or uneven resin flow. The radial pressure actuation unit 2, however, uses multiple independently controllable servo electric cylinders 21 to apply precisely controllable radial pressure to specific local areas of the blank 6, thereby correcting its curvature.

[0034] Radial pressure actuator 2, in conjunction with main pressure actuator 1, suppresses resin overflow while precisely controlling the curvature of blank 6. During the low-viscosity heat preservation stage, resin will be squeezed out of blank 6 in large quantities under excessive main pressure, causing overflow. In this stage, by reducing the main pressure, radial pressure actuator 2 independently applies local radial extrusion to blank 6 to correct the shape, thereby achieving high-precision curvature control with extremely low resin overflow risk. During the cooling stage, blank 6 will shrink, causing the curvature to change (usually becoming smaller). At this time, main pressure actuator 1 switches to position control mode to lock the mold height, while radial pressure actuator actively follows up based on sensor feedback and fine-tunes the pressure it applies to counteract the curvature deformation caused by cooling shrinkage, ensuring that the curvature of the final cooled and shaped curved plate remains accurate.

[0035] Since the servo electric steel 21 outputs a concentrated thrust, if it is directly applied to the composite material blank 6 with low hardness, it will inevitably cause indentation, fiber damage or stress concentration. Therefore, in order to solve this technical problem, a composite pressure foot structure 23 is set at the drive end of multiple servo electric steels 21. The composite pressure foot structure 23 includes a rigid distribution plate 231, a flexible homogenization layer 232 and several ball joint connecting rods 233. The working surface shape of the rigid distribution plate 231 matches the target outline of the arc plate, serving as a robust support back plate to laterally diffuse the concentrated force from the pressure head 22. The flexible homogenization layer 232 is fixedly attached to the working surface of the rigid distribution plate 231, which further homogenizes the force transmitted from the rigid distribution plate 231, forming a soft and evenly distributed surface pressure, thereby protecting the surface quality of the billet 6 and ensuring that the pressure is applied smoothly without any hard spots.

[0036] One end of the ball joint 233 is connected to the corresponding pressure head 22, and the other end is connected to the back of the rigid distribution plate 231. This allows for a certain angular deflection between the pressure head and the rigid distribution plate, ensuring that even if there are minor installation errors or unevenness on the blank surface, the force flow can be smoothly transmitted, avoiding the generation of bending moment.

[0037] Specifically, the sensor system integration unit 4 includes Multiple non-contact displacement sensors 41 are evenly distributed along the curvature of the blank 6 inside the mold body to monitor the positional changes of the edge of the arc plate in real time during the molding process. Multiple dielectric sensors 42 are disposed on the end face of the rigid distribution plate 231 that is in contact with the blank 6. By measuring the dielectric properties of the resin under an alternating electric field, the gelation and curing state of the resin can be reflected in real time. Multiple temperature sensors 43 are installed inside the mold body to monitor the temperature of the mold cavity in real time. A contact position sensor 44 is mounted on the main pressure actuator 1 and is used to measure the displacement of the main pressure actuator 1. Multiple force sensors 45 are integrated between the pressure head 22 and the servo electric cylinder 21 to provide real-time feedback on the radial pressure value applied to the billet 6.

[0038] Specifically, the number of multiple servo electric cylinders 21 corresponds to the number of multiple non-contact displacement sensors 41 and their positions are related, so that at least one servo electric cylinder 21 is responsible for the curvature compensation adjustment of the area monitored by each non-contact displacement sensor 41.

[0039] Specifically, the non-contact displacement sensor 41 is a laser displacement sensor or a spectral confocal sensor, with a sampling frequency of not less than 10 Hz, and the number of installed sensors is not less than 4, and they are evenly distributed along the edge of the arc plate.

[0040] Specifically, the main pressure actuator 1 includes a main pressure cylinder and a servo drive that is connected to the central controller. The central controller sends instructions to the servo drive to control the main pressure cylinder to apply overall pressure according to the segmented pressurization process. The temperature control system integration unit 3 includes a heating subsystem, a cooling subsystem, and a temperature controller. The central controller 5 sends instructions to the heating subsystem and the cooling subsystem according to the target temperature. The temperature controller receives the target temperature instruction from the central controller 5 and feeds back the current temperature, operating status, and fault information to the central controller 5.

[0041] Specifically, the preparation of glass fiber board 61 and epoxy glass fiber mat board 62 includes, by weight, selecting 100-120 parts of bisphenol A epoxy resin, 50-60 parts of silica powder, 6-10 parts of dicyandiamide and 3-4 parts of accelerator, stirring at 60-80℃ for 20-30 minutes, then adding 3-4 parts of fumed silica, and grinding to prepare an adhesive solution; cutting glass fiber cloth and epoxy glass fiber mat according to the arc size of the arc board and impregnating them with the adhesive solution, and then performing vacuum impregnation and curing treatment to form a rigid board structure.

[0042] Silica powder, as an inorganic filler, significantly reduces the curing shrinkage rate and coefficient of thermal expansion of the resin system. The use of the same resin system in both the glass fiber board (flow-blocking layer) and the epoxy glass fiber mat board (flow-guiding layer) minimizes the CTE differences between different layups. During hot pressing, the shrinkage behavior of each layer is relatively consistent, greatly reducing internal stress and warping deformation caused by uneven interlayer shrinkage, a prerequisite for achieving high precision and stable curvature. The latent curing system composed of dicyandiamide and an accelerator ensures the resin remains stable at low temperatures (below 90℃) while reacting rapidly at high temperatures, setting a clear processing window. In particular, the addition of silica, as a highly efficient thixotropic agent, gives the adhesive excellent controllable flowability: maintaining high viscosity in a static state to prevent resin pre-loss after layup and before pressurization; and reducing viscosity under pressure shear, facilitating smooth resin flow and thorough fiber wetting.

[0043] Prepreg blanks themselves possess a certain degree of rigidity and shape retention. When they are placed into the mold, they can better resist pressure and effectively transmit the corrective pressure, rather than easily collapsing or shifting uncontrollably like soft fabrics. This provides a reliable force carrier for the precise curvature correction of the radial actuator.

[0044] Specifically, the fiberglass board uses a single-layer thickness of 0.2mm, and the epoxy fiberglass mat board uses a single-layer thickness of 0.5mm.

[0045] The 0.2mm thin-layer glass fiber board 61, made of dense fiber cloth, forms a highly efficient flow barrier through multiple layers, greatly increasing the resistance to resin overflow while reducing the overall thickness to facilitate heat conduction and uniform pressure distribution. The 0.5mm thick-layer epoxy glass fiber mat 62 provides sufficient resin capacity, ensuring full fiber impregnation and allowing the resin to flow uniformly within the layer, avoiding dry spots. The alternating layers of both form a functional gradient structure: the thin flow barrier layer constrains resin flow, while the thick flow guide layer ensures sufficient reaction, together reducing deformation caused by uneven resin distribution from the material source, providing a stable and predictable molding basis for subsequent high-precision curvature control.

[0046] The table below compares the accuracy of arc control with the effect of resin behavior control in this invention:

[0047] In summary, this invention, through four-dimensional collaborative innovation in materials, structure, process, and control, successfully solves the problems of arc precision control and resin overflow suppression in the hot pressing process of generator insulating ring arc plates.

[0048] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for hot-pressing and controlling the curvature of an arc-shaped insulating ring plate for a generator, characterized in that, Includes the following steps: S1. Establish digital benchmark: Produce a theoretical three-dimensional digital model of the arc plate according to the design requirements of the insulating ring, and set the target value of the arc and the allowable tolerance range; S2. Mold preparation: Positioning a mold that matches the theoretical three-dimensional digital model. The mold includes a main pressure execution unit for hot pressing the arc plate and a radial pressure execution unit for correcting the curvature of the arc plate. It also includes a temperature control system integration unit, a sensor system integration unit, and a central controller. S3. Blank preparation and mold loading: The blank is made of multiple layers of glass fiber board and multiple layers of epoxy glass fiber mat board laid alternately. Glass fiber board is laid as a flow-blocking layer in the outermost layer, the middle layer and the uppermost layer. Epoxy glass fiber mat board is laid between the upper and middle layers and between the lower and middle layers as a flow-guiding and reaction layer. The blank is placed into the mold, the mold is closed and the segmented pressurization program optimized based on finite element hot pressing simulation is set as the initial process parameters. S4. Real-time data acquisition and collaborative control: The hot pressing process is initiated. Through the main pressure execution unit, radial pressure execution unit, sensor system integration unit, and temperature control system integration unit, real-time data is acquired and overall pressure and heat are applied according to the segmented pressurization process. The segmented pressurization process includes the initial compaction stage for initially removing interlayer air and stabilizing the position of the blank, the first preheating and pressurization stage for overall uniform compaction, the low viscosity heat preservation stage for suppressing resin overflow, the gelation and full-pressure shaping stage, and the arc shaping and cooling stage. Each unit coordinates and controls each other to simultaneously suppress resin overflow and control the arc correction during the hot pressing process of the blank. S5. Curing and molding: After the curvature deviation stabilizes within the allowable tolerance range and the preset curing time is reached, the mold is opened and the molded curved plate is taken out after cooling.

2. The method for hot pressing and forming of an arc-shaped insulating ring plate for generators according to claim 1, characterized in that: The specific steps of step S4 include: S41. Initial Compaction Stage: After the mold closes and reaches 90°C, the main pressure actuator applies an overall pressure of 0.2-0.5 MPa to the billet, while the radial pressure actuator simultaneously applies an initial local pressure of 0.1-0.3 MPa to initially remove interlayer air and stabilize the billet position. The sensor system integration unit collects edge position data of the curved plate at a frequency of not less than 10Hz. The central controller calculates the initial curvature deviation. If the deviation exceeds the set threshold, the radial pressure actuator is activated for fine-tuning, with the adjustment range not exceeding 20% ​​of the initial pressure. S42, First preheating and pressurization stage: The temperature control system integrated unit monitors the mold temperature in real time. During this stage, the mold temperature is controlled at 90-120℃. The main pressure execution unit increases the pressure to 0.8–1.2 MPa, and the radial pressure execution unit simultaneously increases the pressure to the same level to achieve uniform compaction. S43, Low viscosity heat preservation stage: During this stage, the mold temperature is controlled at 120-140℃, and the main pressure actuator maintains or slightly reduces the pressure to 0.6–1.0 MPa to suppress resin overflow. The radial pressure actuator independently adjusts the pressure based on the real-time curvature deviation, with an adjustment range of 0.5–1.5 MPa and a response time of no more than 0.5 seconds, ensuring that the curvature deviation is controlled within ±0.1 mm. S44, Gelation and Full Pressure Shaping Stage: The central controller determines the gel point based on the dielectric sensor signal from the integrated sensing system unit and triggers the main pressure execution unit to quickly apply a full pressure of 0.5–1.0 MPa; The radial pressure actuator applies the same full pressure as the main pressure actuator synchronously, and maintains a locked position in the final stage to prevent rebound; S45, Cooling Stage: The main pressure actuator switches to position control mode to maintain a constant mold closing position to compensate for deformation caused by material cooling and shrinkage; The radial pressure actuator makes fine adjustments based on the curvature changes caused by cooling contraction, with the pressure adjustment not exceeding 0.2 MPa, to ensure that the final curvature meets the design requirements.

3. The method for hot pressing and forming of an arc-shaped insulating ring plate for generators according to claim 2, characterized in that: The radial pressure actuation unit includes multiple servo electric cylinders and multiple pressure heads. The cylinder body of the servo electric cylinder is fixed in a preset mounting cavity inside the mold body. The drive end of each servo electric cylinder is connected to the pressure head. The multiple pressure heads are distributed along the arc direction of the blank end. There is a composite pressure foot structure between the multiple pressure heads and the blank to ensure the smoothness of the arc.

4. The method for hot pressing and forming of an arc-shaped insulating ring plate for generators according to claim 3, characterized in that: The composite pressure foot structure includes a rigid distribution plate, a flexible homogenization layer, and several ball joint links. The working surface shape of the rigid distribution plate matches the target outline of the arc plate; The flexible homogenization layer is fixedly attached to the working surface of the rigid distribution plate; One end of the ball joint connecting rod is connected to the corresponding pressure head, and the other end is connected to the back of the rigid distribution plate; The radial pressure actuation unit drives the composite pressure foot structure to convert the concentrated thrust of the pressure head into a uniformly distributed surface pressure that acts on the blank, thereby avoiding local indentations and ensuring a smooth curvature.

5. The method for hot-pressing and forming the arcuate shape of a generator insulating ring arc plate according to claim 4, characterized in that: The sensing system integration unit includes Multiple non-contact displacement sensors are evenly distributed along the curvature of the blank inside the mold body to monitor the positional changes of the edge of the arc plate in real time during the forming process. Multiple dielectric sensors are disposed on the end face of the rigid distribution plate in contact with the blank. By measuring the dielectric properties of the resin under an alternating electric field, the gelation and curing state of the resin can be reflected in real time. Multiple temperature sensors are installed inside the mold body to monitor the temperature of the mold cavity in real time. A contact position sensor is mounted on the main pressure actuator unit to measure the displacement of the main pressure actuator unit; Multiple force sensors are integrated between the pressure head and the servo electric cylinder to provide real-time feedback on the radial pressure applied to the billet.

6. The method for hot pressing and forming of an arc-shaped insulating ring plate for generators according to claim 5, characterized in that: The number of servo electric cylinders corresponds to the number of non-contact displacement sensors and their positions are associated, so that at least one servo electric cylinder is responsible for the curvature compensation adjustment of the area monitored by each non-contact displacement sensor.

7. The method for hot-pressing and controlling the arc of an arc-shaped insulating ring plate for a generator according to claim 6, characterized in that: The non-contact displacement sensor is a laser displacement sensor or a spectral confocal sensor, with a sampling frequency of not less than 10 Hz, and the number of sensors installed is not less than 4, and they are evenly distributed along the edge of the arc plate.

8. The method for controlling the curvature of a generator insulation arc plate according to claim 7, characterized in that: The main pressure execution unit includes a main pressure cylinder and a servo driver that is communicatively connected to the central controller. The central controller sends instructions to the servo driver to control the main pressure cylinder to apply overall pressure according to the segmented pressurization process. The temperature control system integration unit includes a heating subsystem, a cooling subsystem, and a temperature controller. The central controller sends instructions to the heating subsystem and the cooling subsystem according to the target temperature. The temperature controller receives the target temperature instruction from the central controller and feeds back the current temperature, operating status, and fault information to the central controller.

9. The method for controlling the curvature of a generator insulation arc plate according to claim 8, characterized in that: The preparation of the glass fiber board and epoxy glass fiber mat board includes, by weight, selecting 100-120 parts of bisphenol A epoxy resin, 50-60 parts of silica powder, 6-10 parts of dicyandiamide and 3-4 parts of accelerator, stirring at 60-80℃ for 20-30 minutes, then adding 3-4 parts of fumed silica, and grinding to prepare a glue solution; cutting the glass fiber cloth and epoxy glass fiber mat according to the arc size of the arc board and impregnating them with the glue solution, and then performing vacuum impregnation and curing treatment to form a rigid board structure.

10. The method for controlling the curvature of a generator insulation arc plate according to claim 9, characterized in that: The fiberglass board has a single-layer thickness of 0.2mm, and the epoxy fiberglass mat has a single-layer thickness of 0.5mm.

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