A method and system for synergistic curing of composite parts

Abstract

The application provides a synergistic curing method and system of a composite material part, and relates to the technical field of composite material curing. The method comprises the following steps: acquiring internal state information of the composite material part in real time, wherein the internal state information comprises at least one of temperature information and dielectric characteristic information; identifying, based on the internal state information, that the composite material part currently stays in a core heating stage or a reaction heat release stage; in the core heating stage, making the output power of a microwave subsystem dominant to rapidly and uniformly heat; and in the reaction heat release stage, making the output power of a hot air subsystem dominant to inhibit temperature rise. According to the application, the dominant heating of the two heat sources of microwaves and hot air is dynamically switched according to the internal state information, synergistic control is realized, the heating uniformity is improved, the risk of temperature out of control in the reaction heat release stage is reduced, and the curing quality and efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of composite material curing technology, and in particular to a method and system for the synergistic curing of composite material parts. Background Technology

[0002] The molding quality of high-performance composite components is highly dependent on temperature and pressure control during the curing process. Although traditional autoclave curing processes can provide a stable environment, they rely on hot air convection heat transfer, which has inherent drawbacks such as slow heating rate, high energy consumption, and uneven heating of complex components.

[0003] Further improvements attempt to physically integrate energy fields such as microwaves and hot air at the equipment level. For example, the vibration-microwave composite curing system disclosed in Chinese invention patent CN118876467A achieves energy field composite at a single workstation by designing a dedicated device combining a microwave resonant cavity and a vibration table. However, this solution has the following shortcomings at the control level: Insufficient state awareness and delayed response: Control decisions mainly rely on feedback from the cavity environment temperature, lacking direct, online monitoring of the true curing state inside the composite material (such as the degree of resin curing reflected by dielectric properties). This results in the system's inability to identify key process nodes such as the "reaction exothermic initiation point" in a timely manner, leading to passive and delayed control actions, difficulty in suppressing temperature overshoot, and impacting product consistency.

[0004] In summary, existing technologies, by integrating multiple physical energy fields at the device level, provide a new hardware platform for efficient curing. However, their control strategies have failed to achieve a matching intelligent upgrade, remaining at a simple program control stage. This prevents the full potential of advanced hardware from being realized. Therefore, this invention proposes a collaborative curing method and system for composite material parts. By real-time monitoring of the internal temperature and / or dielectric properties of the composite material parts, the core heating stage and the exothermic reaction stage are identified, and microwave and hot air power are dynamically coordinated to fundamentally unleash the potential of the equipment and ensure curing quality and process robustness. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art by proposing a collaborative curing method and system for composite material parts.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for co-curing composite material parts, applied in a curing device including a microwave subsystem, a hot air subsystem, and a sensing and monitoring subsystem, includes the following steps: S1. Acquisition of internal state information: Real-time acquisition of internal state information of composite material parts monitored by the sensing and monitoring subsystem. The internal state information includes at least one of the following: temperature information and dielectric property information. S2. Solidification Stage Identification: Based on the internal state information obtained in step S1, a judgment result is generated, which can be any of the following: The current curing stage of the composite material part is the core heating stage; The current curing stage of the composite material part is the exothermic reaction stage; S3, Coordinated Regulation: Based on the judgment result of step S2; During the core heating phase, the output power of the microwave subsystem becomes dominant. During the exothermic reaction phase, the output power of the hot air subsystem becomes dominant.

[0007] Furthermore, in step S2, when the internal state information is temperature information: If the temperature information is lower than the initial curing temperature of the resin matrix in the composite material part, then the current curing stage is determined to be the core heating stage. If the temperature information is greater than or equal to the initial curing temperature, and the heating rate is greater than the preset heating rate threshold, then the current curing stage is determined to be the exothermic reaction stage.

[0008] Furthermore, in step S2, when the temperature information is greater than or equal to the initial curing temperature and the heating rate is less than or equal to the heating rate threshold, the determination result of the core heating stage is maintained.

[0009] Furthermore, the reinforcement in the composite material component is continuous carbon fiber.

[0010] The reinforcement in the composite material part is an insulating fiber with a dielectric loss factor of less than 0.01; Furthermore, in step S2, when the internal state information is dielectric characteristic information, the dielectric characteristic information is the dielectric loss factor: If the dielectric loss factor has not yet reached its peak value during the monitoring process, the current solidification stage is determined to be the core heating stage. If the dielectric loss factor reaches its peak and begins to show a continuous downward trend, then the current curing stage is determined to be the exothermic reaction stage.

[0011] Furthermore, in step S2, when the internal state information includes both temperature information and dielectric property information: Calculate the comprehensive state function value based on temperature and dielectric properties information; If the overall state function value is less than the preset state function threshold, then the current solidification stage is determined to be the core heating stage. If the comprehensive state function value is greater than or equal to the preset state function threshold, then the current solidification stage is determined to be the exothermic reaction stage.

[0012] Furthermore, the comprehensive state function value is calculated using the following formula: ,in, Ф(t) represents the comprehensive state function value at time t; ε(t) represents the dielectric loss factor monitored in real time at time t; ε ref Indicates the preset reference dielectric loss factor; m represents the exponential weight of the dielectric signal; (dT / dt)(t) represents the real-time heating rate at time t; (dT / dt) th This indicates the preset heating rate threshold. n represents the exponential weight of the heating rate.

[0013] Furthermore, in step S3, the output power of the microwave subsystem being dominant means that the output power of the microwave subsystem accounts for more than 60% of the total output power of the microwave subsystem and the hot air subsystem; the output power of the hot air subsystem being dominant means that the output power of the hot air subsystem accounts for more than 60% of the total output power of the microwave subsystem and the hot air subsystem.

[0014] Furthermore, during the core heating phase, step S1 is executed again to continue acquiring internal status information.

[0015] Furthermore, a composite material co-curing system for performing a co-curing method for a composite material part as described above includes: A sealed and pressure-resistant curing chamber; Microwave subsystem and hot air subsystem are installed inside the curing chamber; The sensing and monitoring subsystem is configured to monitor the internal state information of the composite material part placed in the curing chamber in real time. The collaborative control subsystem is communicatively connected to the microwave subsystem, the hot air subsystem, and the sensing and monitoring subsystem, and is configured to perform the collaborative curing method for composite material parts as described above.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. During the core heating stage, the microwave subsystem serves as the primary heat source, utilizing the volumetric heating characteristics of microwaves to directly heat the interior of the composite material part, shortening the heating time and reducing the core-surface temperature difference. During the reaction exothermic stage, the hot air subsystem serves as the primary heat source, providing heat and assisting in heat dissipation through convection heat transfer, suppressing excessively rapid temperature rise caused by the exothermic resin crosslinking reaction, and reducing the risk of temperature runaway. Thus, both heating efficiency and temperature uniformity are achieved within the same process cycle. 2. Based on temperature and / or dielectric property information, the power ratio of the microwave subsystem and the hot air subsystem is dynamically adjusted through curing stage identification to achieve coordinated control. When both temperature and dielectric property information are used simultaneously, a comprehensive state function value can be calculated and compared with a state function threshold to determine the core heating stage and the reaction exothermic stage. 3. This method uses temperature information for stage identification of continuous carbon fiber reinforced composite materials, and uses temperature information, dielectric property information, or a combination of both for stage identification of insulating fiber reinforced composite materials with a dielectric loss factor of less than 0.01, adapting to the microwave heating characteristics of different fiber types and improving process applicability. 4. The identification of the curing stage and the adjustment of the power ratio are based on the real-time monitoring of internal status information, without relying on fixed time programs, reducing deviations caused by material batch differences or process fluctuations, and improving the consistency and automation of the curing process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structural framework of the present invention; Figure 2 This is a flowchart of the temperature-information-based collaborative curing method of the present invention; Figure 3 This is a flowchart of the collaborative curing method based on dielectric property information of the present invention; Figure 4 This is a flowchart of the method for co-curing temperature information and dielectric property information according to the present invention. Figure 5 This is a top view schematic diagram of the curing device of the present invention; In the diagram, 1. Curing chamber, 2. Metal partition, 3. Shielding door, 4. Microwave subsystem, 41. Microwave generator, 42. Microwave feed structure, 43. Microwave field homogenization device, 5. Hot air subsystem, 51. Heater, 52. Circulating fan, 53. Hot air channel, 54. Air inlet, 55. Air return outlet, 6. Sensing and monitoring subsystem, 61. Temperature sensor, 62. Fiber optic demodulator, 63. Dielectric sensor, 64. Power monitoring device, 65. Dielectric property monitoring unit, 7. Cooperative control subsystem, 71. Central controller. Detailed Implementation

[0018] 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.

[0019] Before describing the specific implementation methods, some of the terms used in this invention are explained as follows: The composite material component is a prepreg laminate, preform, or sandwich structure consisting of a reinforcement and a resin matrix; the sandwich structure includes a structure composed of a composite material panel and a core material. The resin matrix is ​​a thermosetting resin, such as epoxy resin, bismaleimide resin, or cyanate ester resin; the reinforcement can be continuous carbon fiber, glass fiber, aramid fiber, or quartz fiber, etc. The initial curing temperature of the resin matrix in the composite material component (the critical temperature that characterizes the start of a significant crosslinking reaction of the resin) can be determined in advance by differential scanning calorimetry.

[0020] The core heating stage refers to the stage where the resin matrix in the composite material part has not yet undergone significant cross-linking reaction; the exothermic reaction stage refers to the stage where the resin matrix undergoes significant cross-linking reaction accompanied by exothermic reaction. The specific determination methods for the two stages (temperature criterion, dielectric loss factor peak criterion, or comprehensive state function criterion) are shown in the following embodiments.

[0021] The dielectric loss factor is the imaginary part of the complex dielectric constant, used to characterize the dielectric loss capability of a material in a microwave field. In this invention, the dielectric loss factor is calculated by the dielectric property monitoring unit 65 based on the output of the dielectric sensor 63 or the power monitoring device 64, and is used for identification during the curing stage.

[0022] Example 1: The composite material part described in this invention is a prepreg laminate or preform composed of a reinforcement and a resin matrix. The resin matrix is ​​a thermosetting resin, such as epoxy resin, bismaleimide resin, or cyanate ester resin; the reinforcement can be continuous carbon fiber, glass fiber, aramid fiber, or quartz fiber, etc. The initial curing temperature of the resin matrix in the composite material part can be determined in advance by differential scanning calorimetry.

[0023] like Figures 1-2 As shown, this embodiment provides a co-curing system for composite material parts. The system includes a curing device and a co-control subsystem 7. The curing device includes: A sealed and pressure-resistant curing chamber 1; Microwave subsystem 4 and hot air subsystem 5 are installed inside curing chamber 1; The sensing and monitoring subsystem 6 is configured to monitor the internal state information of the composite material part placed in the curing chamber 1 in real time; The collaborative control subsystem 7 is communicatively connected to the microwave subsystem 4, the hot air subsystem 5, and the sensing and monitoring subsystem 6, and is configured to perform a collaborative curing method for composite material parts.

[0024] In this embodiment, the curing chamber 1 can adopt existing technology. The curing chamber 1 is a vertical cylindrical pressure vessel made of stainless steel, with loading / unloading ports with shielded doors 3 on both end side walls, and functional module interfaces provided at the top and bottom. The design working pressure is 0-1.0 MPa, and the maximum withstand temperature is 300℃.

[0025] The microwave subsystem 4 includes multiple microwave generators 41, a microwave feed structure 42, and a microwave field homogenization device 43. The microwave generators 41 are arranged outside the curing cavity 1. The microwave feed structure 42 penetrates the wall of the curing cavity 1, with one end connected to the microwave generator 41 and the other end introducing microwave energy into the curing cavity 1.

[0026] The microwave field homogenization device 43 is fixed to the top plate inside the curing cavity 1 and is located at the output end of the microwave feed structure 42. Specifically, the microwave field homogenization device 43 is a rotary microwave stirrer, including a metal blade and a drive motor. The metal blade is located below the top plate inside the curing cavity 1, and the drive motor is located outside the curing cavity 1. The output shaft of the drive motor passes through the wall of the curing cavity 1 and is connected to the metal blade to drive the metal blade to rotate. The control terminal of the drive motor is communicatively connected to the cooperative control subsystem 7 and receives its commands regarding start / stop and speed. The microwave field homogenization device 43 is used to drive the metal blade to rotate, continuously disturbing the electromagnetic boundary conditions inside the cavity, causing the resonant mode to switch dynamically, thereby breaking standing waves and multimode interference, ensuring that microwave energy is uniformly distributed in the three-dimensional space of the composite material part, and avoiding local overheating or underheating.

[0027] The control terminal of the microwave field homogenization device 43 is communicatively connected to the cooperative control subsystem 7, and receives its instructions regarding the working mode (such as start / stop, speed).

[0028] The hot air subsystem 5 provides a uniform and controllable convective thermal environment to the curing chamber 1 and works in conjunction with the microwave subsystem 4 to achieve composite heating of the composite material parts. This system mainly includes: The heater 51, which serves as the heat source for the curing chamber 1, is composed of a high-power electric heating tube array and is used to heat the circulating air to a set temperature.

[0029] The circulating fan 52 is a centrifugal fan that provides the power for forced air circulation, ensuring that hot air flows within the curing chamber 1 to form convective hot air.

[0030] The hot air duct 53 is a piping system connecting the heater 51, the circulating fan 52, and the curing chamber 1. The inner wall is lined with insulation material to reduce heat loss. The hot air duct 53 delivers heated air to the bottom or side air inlet 54 of the curing chamber 1. After forming a uniform flow field in the curing chamber 1, the air returns to the hot air subsystem 5 through the return air inlet 55 for reheating, forming a closed loop.

[0031] A pressure control system, designed to provide a precise pressure environment for the curing process and compatible with existing technologies, includes auxiliary actuators, specifically an external vacuum pump assembly, a pressurizing device, and pressure sensors inside the curing chamber 1. The vacuum pump assembly and pressurizing device are connected to the curing chamber 1 via sealed piping and a control valve assembly. The collaborative control subsystem 7, based on feedback signals from the pressure sensors, programmatically controls the coordinated actions of the vacuum pump assembly, pressurizing device, and control valve assembly, achieving precise pressure control within the range of 0.001-1.0 MPa to achieve process objectives such as eliminating air bubbles, removing volatiles, and ensuring the density of composite material parts. For example, it executes a sequence of instructions such as "evacuate to 0.01 MPa, then pressurize to 0.6 MPa".

[0032] The temperature monitoring unit includes a fiber Bragg grating temperature sensor 61 and a fiber Bragg grating demodulator 62. The fiber Bragg grating temperature sensor 61 is embedded inside the composite material part to sense temperature changes and output an optical signal. The fiber Bragg grating temperature sensor 61 is connected to the fiber Bragg grating demodulator 62 via an optical cable that penetrates the sealed interface of the curing chamber 1. The fiber Bragg grating demodulator 62, based on a preset wavelength-temperature calibration curve, calculates the optical signal output by the fiber Bragg grating temperature sensor 61 to obtain the temperature information inside the composite material part, and transmits this temperature information to the collaborative control subsystem 7. The fiber Bragg grating temperature sensor 61 includes a grating region and leads; the grating region is used to sense temperature, and the leads are used to transmit the optical signal to the fiber Bragg grating demodulator 62.

[0033] The dielectric property monitoring unit 65 includes a dielectric sensor 63 and a power monitoring device 64. The dielectric sensor 63 is directly disposed within the curing chamber 1 or near the composite material part for measurement. Specifically, the dielectric sensor 63 is an interdigitated electrode or a parallel plate electrode. The interdigitated electrode includes a substrate and interdigitated conductive electrodes disposed on the substrate, the interdigitated conductive electrodes being in contact with the resin matrix in the composite material part; the parallel plate electrode includes two opposing conductive plates, with the resin matrix to be measured disposed between the two conductive plates. The dielectric sensor 63 obtains the dielectric loss factor of the resin matrix by measuring the impedance or capacitance change of the interlayer resin medium. The dielectric property monitoring unit 65 calculates the dielectric loss factor based on the signal output by the dielectric sensor 63 and transmits it to the collaborative control subsystem 7.

[0034] The collaborative control subsystem 7 includes a central controller 71, which is an industrial computer or a PLC. The central controller 71 includes a storage unit and a processing unit. The storage unit pre-stores control programs and control threshold parameters, including initial curing temperature, heating rate threshold, and state function threshold. The processing unit is used to load and run the control program and perform the following steps: based on the internal state information obtained by the sensing and monitoring subsystem 6, a judgment result is generated, and according to the judgment result, the output power of the microwave subsystem 4 is made dominant during the core heating stage, and the output power of the hot air subsystem 5 is made dominant during the reaction exothermic stage.

[0035] The input end of the collaborative control subsystem 7 is connected to the sensing and monitoring subsystem 6, and the output end is connected to the control end of the auxiliary execution components of the microwave subsystem 4, the hot air subsystem 5, and the curing chamber 1, forming a closed-loop control system.

[0036] Based on the curing stage identification results, the collaborative control subsystem 7 generates microwave control commands and hot air control commands. The microwave control commands are transmitted to the power control terminal of the microwave generator 41 to adjust the output power of the microwave subsystem 4; the hot air control commands are transmitted to the control terminals of the heater 51 and the circulating fan 52 to adjust the output power of the hot air subsystem 5. The collaborative control subsystem 7 also generates curing chamber management commands, which control the drive mechanism of the shielding door 3 of the curing chamber 1, as well as the control valve group and vacuum pump group of the pressure control system, to manage the sealing status and pressure environment of the curing chamber 1.

[0037] To achieve efficient synergy between microwave energy and convective hot air, a metal partition 2 is installed inside the curing chamber 1 in this embodiment. The metal partition 2 axially divides the curing chamber 1 into an upper microwave action zone and a lower hot air circulation zone. Multiple ventilation holes are provided on the metal partition 2, and each ventilation hole contains a cutoff waveguide structure. The cutoff frequency of the cutoff waveguide structure is higher than the operating frequency of the microwave subsystem 4, allowing hot air to flow vertically through the metal partition 2 while preventing microwave energy from passing through it. As an example, for microwaves operating at 2.45 GHz, the ventilation holes are circular cutoff hole arrays or rectangular cutoff waveguide arrays with a diameter less than one-quarter of the microwave wavelength (approximately 30 mm).

[0038] Above the metal partition 2, a microwave-transmitting stage is provided for placing the composite material part to be cured. The stage is preferably a grid structure made of quartz or ceramic material to ensure that it does not block microwave energy while allowing hot air from below to pass through smoothly.

[0039] During operation, the composite material part is placed on the platform. The convective hot air generated by the hot air subsystem 5 passes through the ventilation holes on the metal partition 2 and continues to penetrate the grid of the platform, forming convective heating that wraps around the workpiece from bottom to top. The microwave energy generated by the microwave subsystem 4 is fed in from above or from the side, penetrating the platform and the air medium surrounding the composite material part to heat the composite material part.

[0040] Thus, the metal partition 2 and the stage together define a collaborative heating working area where microwaves and hot air act separately and do not interfere with each other.

[0041] Example 2, refer to Figure 2 As shown, this embodiment provides a method to identify the core heating stage and the reaction exothermic stage simply by judging the internal temperature of the composite material part, that is, to dynamically adjust the dominant heat source based on the internal temperature information.

[0042] First, the following parameters are preset in the collaborative control subsystem 7: Initial curing temperature; Heating rate threshold: set to 2.0℃ / min.

[0043] The co-curing method includes the following steps: S1. Acquisition of internal status information: Real-time acquisition of internal temperature information of composite material parts monitored by the sensing and monitoring subsystem 6; The temperature values ​​obtained from continuous sampling are processed by moving average, and then the real-time heating rate is calculated using first-order backward difference. The calculation formula is as follows: , in, dT / dt(t) represents the real-time heating rate at time t, with units of ℃ / s, i.e., the rate of change of temperature with time t; T(t) represents the temperature value at time t; T(t−Δt) represents the temperature value at the previous sampling time; Δt represents the sampling time interval of the sensing and monitoring subsystem 6, which is 1 second in this embodiment. When expressed in minutes, it is 1 / 60 of a minute. The calculated heating rate is in °C / min and is compared with the heating rate threshold.

[0044] S2. Curing Stage Identification Step: Based on the temperature information obtained in step S1, a judgment result is generated to determine whether the current curing stage of the composite material part is the core heating stage or the reaction exothermic stage. The collaborative control subsystem 7 makes the determination, and the specific determination logic is as follows: When the temperature information is lower than the initial curing temperature, the current curing stage is determined to be the core heating stage. When the temperature information is greater than or equal to the initial curing temperature and the heating rate is greater than the heating rate threshold, the current curing stage is determined to be the exothermic reaction stage. When the temperature information is greater than or equal to the initial curing temperature, and the heating rate is less than or equal to the heating rate threshold, the determination result of the core heating stage is maintained.

[0045] S3, Coordinated Regulation: Based on the judgment result of step S2, During the core heating phase, the output power of microwave subsystem 4 becomes dominant. During the exothermic reaction phase, the output power of the hot air subsystem 5 becomes dominant.

[0046] Wherein, the output power of microwave subsystem 4 is dominant means that the output power of microwave subsystem 4 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%; the output power of hot air subsystem 5 is dominant means that the output power of hot air subsystem 5 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%.

[0047] During the core heating phase, the collaborative control subsystem 7 repeats step S1 to continuously acquire internal temperature information until it determines that the reaction has entered the exothermic phase.

[0048] Temperature information is obtained by a temperature sensor 61 embedded inside the composite material part. To ensure control accuracy, areas within the composite material part that exhibit high thermal inertia, lag in temperature response, and a tendency for heat accumulation are given special attention. In practical applications, this area typically corresponds to the core material region in composite material parts with a sandwich structure.

[0049] In this embodiment, the temperature sensor 61 is preferably a fiber Bragg grating temperature sensor. Its bare fiber diameter is approximately 125 micrometers, and after being coated with a high-temperature resistant polyimide layer, the diameter is less than 250 micrometers to reduce its impact on the structure of the composite material part. The fiber Bragg grating temperature sensor is unaffected by microwave field interference and is suitable for temperature measurement inside continuous carbon fiber reinforced composite parts.

[0050] When laying composite prepreg, one or more fiber optic temperature sensors are embedded in areas of the composite part where temperature needs to be monitored, such as thick core areas or areas with complex geometries that are prone to heat concentration, according to a preset path.

[0051] The core material region refers to the lightweight core layer (such as honeycomb, foam, or wood core material) located between two high-strength composite material panels in a sandwich structure composite component. Due to its relatively large structural thickness and low thermal conductivity, this core material region exhibits significant thermal behavior hysteresis throughout the curing process. Specifically: During the core heating phase, the temperature rises relatively slowly in this region, which is the bottleneck restricting the overall heating efficiency. During the exothermic reaction stage, the heat generated by the resin curing reaction is difficult to dissipate in time through the low thermal conductivity core material, which easily forms local hot spots and leads to temperature runaway. This is the core risk area for defects such as scorching, decomposition, or interface debonding in composite parts.

[0052] Based on the above analysis, in this embodiment, the temperature sensor 61 is directly embedded inside the core material area or at the interface between the core material and the panel during the installation process.

[0053] In this embodiment, the composite material component is a carbon fiber skin / Nomex honeycomb sandwich structure, wherein the carbon fiber skin is made of carbon fiber / epoxy resin prepreg. During the installation process, the sensing point of the fiber grating temperature sensor is guided and embedded in the honeycomb core cell below the thickest dome region of the carbon fiber skin, and fixed with a high-temperature adhesive film to directly sense the true temperature inside the core material. To avoid strain interference introduced by the curing shrinkage of the high-temperature adhesive film or the deformation of the composite material to the fiber grating, the grating area can be encapsulated in a relaxed non-metallic capillary, fixing only the fiber leads; or a temperature compensation grating can be set so that wavelength drift mainly reflects temperature changes. The selected fiber grating sensor has a small diameter, for example, no more than 250 μm, and its impact on the core material structure and mechanical properties after embedding is negligible.

[0054] By directly monitoring the internal temperature of the core material region, the most representative key data of the entire composite material curing process were obtained. This enables the collaborative control subsystem 7 to implement precise, phased control.

[0055] During the core heating stage, the collaborative control subsystem 7 controls the microwave subsystem 4 as the dominant heat source, ensuring that its output power accounts for more than 60% of the total output power of the microwave subsystem 4 and the hot air subsystem 5, preferably 70% to 90%. Utilizing the volumetric heating characteristics of microwaves, the overall temperature of the composite material part is directly increased, especially the core material region with high thermal inertia, allowing it to be rapidly and uniformly heated from its initial temperature to near the initial curing temperature, thus providing uniform temperature conditions for temperature control in the subsequent exothermic reaction stage.

[0056] When the collaborative control subsystem 7 determines that the reaction has entered the exothermic stage, the control strategy switches to: reducing or shutting down the output power of the microwave subsystem 4, while controlling the hot air subsystem 5 as the dominant heat source, ensuring that its output power accounts for more than 60% of the total output power of the microwave subsystem 4 and the hot air subsystem 5. The hot air subsystem 5 provides heat and assists in heat dissipation through convection heat transfer, suppressing the heating rate within the heating rate threshold and reducing the risk of overheating due to excessively rapid heating.

[0057] Based on this, during the core heating stage, the system's main task focuses on efficient and uniform physical heat transfer, namely: fully utilizing the volumetric heating characteristics of microwaves to rapidly and uniformly heat the entire composite material part—especially the core material region with high thermal inertia—from its initial temperature to the initial curing temperature, thereby laying the necessary temperature foundation for the subsequent precise control of the intense "reaction exothermic stage." The identification of this stage is performed by the collaborative control subsystem 7.

[0058] Once the exothermic reaction phase ends and the composite material part has completed the preset heat preservation, the curing phase is considered complete. The collaborative control subsystem 7 generates a process completion signal, which can trigger an alarm signal or automatically execute subsequent operations such as depressurization, chamber opening, and mold removal.

[0059] Example 3, referring to Figure 3 As shown, this embodiment provides a synergistic curing method that uses dielectric loss factor to identify the core heating stage and the reaction exothermic stage, and dynamically adjusts the dominant heat source by dielectric loss factor. The reinforcement in the composite material part is an insulating fiber with a dielectric loss factor of less than 0.01, such as glass fiber, quartz fiber or aramid fiber.

[0060] First, the following parameters are preset in the collaborative control subsystem 7: Sampling period: set to 1 second; Time window W: Set to 30 seconds; Cumulative decrease threshold η: set to 5% of the peak value.

[0061] The co-curing method includes the following steps: S1. Acquisition of Internal State Information: The internal state information of the composite material part monitored by the sensing and monitoring subsystem 6 is acquired in real time. The internal state information is dielectric property information, and the dielectric property information is dielectric loss factor. In this embodiment, the dielectric property monitoring unit 65 acquires the dielectric loss factor through at least one of the following methods: Method 1: The power monitoring device 64 monitors the incident power and reflected power of the microwave subsystem 4 in real time. The dielectric property monitoring unit 65 calculates the equivalent complex dielectric constant of the composite material part based on the incident power and reflected power, using microwave transmission line theory or cavity perturbation theory, and extracts the imaginary part of the equivalent complex dielectric constant as the dielectric loss factor. This method eliminates the need to add sensors inside the composite material part. Specifically, the dielectric property monitoring unit 65 performs pre-calibration: a standard sample with a known dielectric loss factor is placed in the curing cavity, and the incident power and reflected power are recorded under different conditions to establish a calibration curve or mapping table between the reflection characteristics and the dielectric loss factor; during the curing process, the current dielectric loss factor is derived by back-calculating the incident power and reflected power measured in real time according to the calibration curve or mapping table.

[0062] Method 2: The dielectric sensor 63 is embedded in a predetermined key location inside the composite material part, such as the thickest part or geometric center of the composite material part, areas with concentrated heat or slow curing reaction. The embedding method of the dielectric sensor 63 is the same as described above: when laying the prepreg stack, the probe of the dielectric sensor 63 is placed between predetermined layers, so that the sensitive element is in direct contact with the resin matrix in the composite material part, and the connection end is led to the outside of the mold through a flexible wire to connect with the dielectric property monitoring unit 65.

[0063] The output of the dielectric property monitoring unit 65 is connected to the input of the cooperative control subsystem 7 to transmit the dielectric loss factor to the cooperative control subsystem 7 in real time.

[0064] S2. Curing Stage Identification: Based on the dielectric loss factor obtained in step S1, a judgment result is generated to determine whether the current curing stage of the composite material part is the core heating stage or the reaction exothermic stage.

[0065] The specific judgment logic is as follows: If the dielectric loss factor has not yet reached its peak value during the monitoring process, the current solidification stage is determined to be the core heating stage. If the dielectric loss factor reaches its peak and begins to show a continuous downward trend, then the current curing stage is determined to be the exothermic reaction stage.

[0066] Whether the dielectric loss factor reaches its peak and begins to decline continuously is determined based on a preset continuous decline criterion. This continuous decline criterion is composed of a time window W and a cumulative decline threshold η. The specific determination process is as follows: ① Peak tracking: At each sampling time t, the maximum value of the dielectric loss factor measured at each sampling time between the start of monitoring and the current time t is recorded as the peak value P(t), that is, P(t)=max {ε(τ)|τ∈[0, t]}, where ε(τ) represents the dielectric loss factor monitored in real time at time τ; ② Calculation of relative decrease: Calculate the decrease of the current dielectric loss factor relative to the peak value D(t) = [P(t) - ε(t)] / P(t) × 100%, where ε(t) represents the dielectric loss factor at time t; ③ Continuous decline determination: When D(t) > η at time t, and D > η is satisfied at each sampling time within the continuous time window from time t-W to time t, that is, when the state of the relative peak decline exceeds the threshold is continuously established within the time window W, it is determined that the dielectric loss factor has reached the peak and is in a continuous decline trend, and then it is determined that the composite material part has entered the reaction exothermic stage. ④ Judgment retention: After entering the exothermic reaction stage, the judgment result is maintained until the curing process is completed, and it will not be reset due to fluctuations in the dielectric loss factor.

[0067] In this example, the time window W is set to 30 seconds, and the cumulative decrease threshold η is set to 5% of the peak value. When the dielectric loss factor decreases by more than 5% of the peak value within 30 consecutive seconds, it is determined that the peak value has been reached and the factor has begun to decrease continuously.

[0068] S3. Coordinated Control: Based on the determination result of step S2, during the core heating stage, the output power of microwave subsystem 4 is made dominant; during the reaction exothermic stage, the output power of hot air subsystem 5 is made dominant.

[0069] Wherein, the output power of microwave subsystem 4 is dominant means that the output power of microwave subsystem 4 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%; the output power of hot air subsystem 5 is dominant means that the output power of hot air subsystem 5 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%.

[0070] During the core heating phase, the collaborative control subsystem 7 repeats steps S1 and S2 until it is determined that the reaction has entered the exothermic phase.

[0071] The control strategy is as follows: During the core heating phase, the collaborative control subsystem 7 controls the microwave subsystem 4 as the dominant heat source, ensuring that its output power accounts for more than 60% of the total output power of the microwave subsystem 4 and the hot air subsystem 5. Utilizing the volumetric heating characteristics of microwaves, the insulating fiber-reinforced composite material part is heated as a whole, allowing it to rapidly rise from its initial temperature.

[0072] When the collaborative control subsystem 7 determines that the reaction has entered the exothermic stage, it reduces the output power of the microwave subsystem 4, ensuring that the output power of the hot air subsystem 5 accounts for more than 60% of the total output power of the microwave subsystem 4 and the hot air subsystem 5. The output power of the microwave subsystem 4 can be reduced to zero. The hot air subsystem 5 provides heat and assists in heat dissipation through convection heat transfer, suppressing excessively rapid temperature rise caused by the exothermic reaction of the resin crosslinking.

[0073] Once the composite material part has completed the preset heat preservation time, the curing process is considered complete. The collaborative control subsystem 7 generates a process completion signal, which can trigger an alarm signal or automatically execute subsequent operations such as depressurization, chamber opening, and mold removal.

[0074] This embodiment identifies the exothermic reaction stage by the dielectric loss factor reaching its peak and then continuously decreasing. It can determine the curing stage without relying on temperature information and is applicable to composite material parts with insulating fibers whose reinforcement has a dielectric loss factor of less than 0.01, such as glass fiber / epoxy resin laminates, quartz fiber / epoxy resin laminates, or glass fiber skin / Nomex honeycomb sandwich structures.

[0075] Example 4, refer to Figure 4 As shown, this embodiment illustrates a specific implementation method for identifying the curing stage by fusing temperature information and dielectric loss factor. The comprehensive state function value is compared with a preset state function threshold to identify the core heating stage and the reaction exothermic stage, and the power ratio of the microwave subsystem 4 and the hot air subsystem 5 is dynamically adjusted based on the identification results.

[0076] In this embodiment, the reinforcement of the composite material part is an insulating fiber with a dielectric loss factor of less than 0.01, such as glass fiber, quartz fiber or aramid fiber.

[0077] The composite material parts use glass fiber / epoxy resin prepreg, and the following parameters are preset in the collaborative control subsystem 7: Initial curing temperature T0: 120℃; Reference dielectric loss factor ε ref ; can be taken as the stable value of the dielectric loss factor in the initial stage of curing, such as the average value of the stable period at room temperature, which is set to 0.05 in this embodiment; Temperature rise rate threshold (dT / dt) th In this embodiment, the speed is set to 2.0℃ / min. The exponential weight m of the dielectric signal is set to 1.2 in this embodiment. The exponential weight n of the heating rate is set to 1.0 in this embodiment. State function threshold Ф th In this embodiment, it is set to 1.0; In this embodiment, the reference dielectric loss factor ε ref =0.05 represents the stable value at room temperature. In the initial stage of the core heating phase, moisture and volatiles in the resin matrix are released as the temperature rises, and the dielectric loss factor temporarily decreases due to the decrease in water content. Subsequently, as the temperature continues to rise, ion migration intensifies, and the cross-linking reaction begins, the dielectric loss factor rises again. Therefore, in the subsequent exemplary calculations, the dielectric loss factor monitored at 80°C is 0.03, lower than the reference value of 0.05. This is a reasonable phenomenon of the change in the dielectric properties of the resin matrix with temperature and volatiles during this stage. Those skilled in the art should understand that this change does not affect the logic used to distinguish between the core heating phase and the exothermic reaction phase using the comprehensive state function value. The specific values ​​of the above parameters can be determined through experiments or simulations based on the composite material system used and the target process trajectory.

[0078] For common epoxy resin-based thermosetting composite materials, the state function threshold can range from 0.5 to 2.0. For the glass fiber / epoxy resin prepreg involved in this embodiment, the state function threshold can be selected between 0.5 and 2.0 through differential scanning calorimetry and pre-experimental calibration. In a preferred embodiment, the state function threshold is set to 1.0, and this threshold can be adjusted according to the specific material formulation and process requirements.

[0079] The co-curing method includes the following steps: S1. Obtaining internal status information: The internal state information of the composite material part monitored by the sensing and monitoring subsystem 6 is acquired in real time. The internal state information includes temperature information and dielectric property information, wherein the dielectric property information is the dielectric loss factor.

[0080] Temperature information and dielectric loss factor are collected simultaneously, with a sampling period of 1 second.

[0081] S2, Curing Stage Identification Step: Based on the temperature information and dielectric loss factor obtained in step S1, calculate the comprehensive state function value, compare the comprehensive state function value with the state function threshold, and generate a judgment result; The specific judgment logic is as follows: If the comprehensive state function value is less than the state function threshold Ф th If so, the current solidification stage is determined to be the core heating stage; If the comprehensive state function value is greater than or equal to the state function threshold Ф th If so, the current solidification stage is determined to be the exothermic reaction stage; Furthermore, considering that in the later stages of the exothermic reaction, as the resin crosslinking reaction nears completion, both the dielectric loss factor and the heating rate decrease, and the overall state function value will again fall below the state function threshold, the collaborative control subsystem 7 executes a decision-holding rule: once the exothermic reaction stage is determined, the decision result is maintained, and the output power of the hot air subsystem 5 remains dominant until the curing process is complete, instead of switching back to the core heating stage based on the decrease in the overall state function value. This avoids misjudgment in the later stages of exothermic reaction that could cause the microwave subsystem 4 to regain dominance, preventing the cured area from being overheated again.

[0082] First, based on the temperature information obtained in step S1, the real-time heating rate is calculated. Specifically, the continuously sampled temperature values ​​are processed by moving average, and then the real-time heating rate is calculated using first-order backward difference. The calculation formula is as follows: , in, dT / dt(t) represents the real-time heating rate at time t, with units of ℃ / s, i.e., the rate of change of temperature with time t; T(t) represents the temperature value at time t; T(t−Δt) represents the temperature value at the previous sampling time; Δt represents the sampling time interval of the sensing and monitoring subsystem 6, which is 1 second in this embodiment. When expressed in minutes, it is 1 / 60 of a minute. The calculated heating rate is in °C / min, which is then substituted into the comprehensive state function formula for calculation.

[0083] Next, calculate the comprehensive state function value. The collaborative control subsystem 7 calculates the comprehensive state function value in real time. The calculation frequency is set to be consistent with the sampling frequency interval, i.e., once per second. Based on the dielectric loss factor obtained in step S1 and the real-time heating rate calculated above, combined with the preset reference dielectric loss factor ε, ref Temperature rise rate threshold (dT / dt) th The state function value is calculated iteratively using the following formula, where the exponential weight m of the dielectric signal and the exponential weight n of the heating rate are used: , in, Ф(t) represents the comprehensive state function value at time t; ε(t) represents the dielectric loss factor monitored in real time at time t; ε ref Indicates the preset reference dielectric loss factor; m represents the exponential weight of the dielectric signal; (dT / dt)(t) represents the real-time heating rate at time t; (dT / dt) th This indicates the preset heating rate threshold; n represents the exponential weight of the preset heating rate.

[0084] At 300 seconds after the start of curing, i.e., t=300s, real-time monitoring showed that ε(300) = 0.03. The temperature values ​​of two consecutive samplings are: T(300)=80.00℃, T(299)=79.98℃ The real-time heating rate is calculated based on the first-order backward difference: dT / dt(300)=(80.00-79.98)℃ / 1=0.02℃ / s=1.2℃ / min; Substitute the above data into the comprehensive state function formula:

[0085] Since 0.325 < 1.0, according to the judgment rule, if the comprehensive state function value is less than the state function threshold Ф... th If so, the current solidification stage is determined to be the core heating stage.

[0086] At 600 seconds after the start of curing, i.e., t=600s, real-time monitoring showed that ε(600) = 0.1. The temperature values ​​of two consecutive samplings are: T(600) = 130.00℃, T(599) = 129.95℃. The real-time heating rate is calculated based on the first-order backward difference: dT / dt(600)=(130.00-129.95)℃ / 1=0.05℃ / s=3.0℃ / min; Substitute the above data into the comprehensive state function formula:

[0087] Since 3.446 > 1.0, according to the judgment rule, if the comprehensive state function value is greater than or equal to the state function threshold, then the current solidification stage is determined to be the exothermic reaction stage.

[0088] S3. Coordinated Regulation: Based on the judgment result of step S2, the control strategy is as follows: During the core heating stage, the output power of microwave subsystem 4 is made dominant; during the reaction exothermic stage, the output power of hot air subsystem 5 is made dominant. Wherein, the output power of microwave subsystem 4 is dominant means that the output power of microwave subsystem 4 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%; the output power of hot air subsystem 5 is dominant means that the output power of hot air subsystem 5 accounts for more than 60% of the total output power of microwave subsystem 4 and hot air subsystem 5, preferably 70% to 90%.

[0089] During the core heating stage, the collaborative control subsystem 7 repeatedly executes steps S1 and S2, continuously acquiring temperature information and dielectric loss factor and performing curing stage identification until it is determined that the reaction exothermic stage has been entered.

[0090] During the core heating phase, the collaborative control subsystem 7 controls the microwave subsystem 4 as the primary heat source, utilizing the volumetric heating characteristics of microwaves to heat the insulating fiber-reinforced composite material parts as a whole.

[0091] When the collaborative control subsystem 7 determines that the reaction has entered the exothermic stage, it reduces the output power of the microwave subsystem 4, ensuring that the output power of the hot air subsystem 5 accounts for more than 60% of the total output power of the microwave subsystem 4 and the hot air subsystem 5. The output power of the microwave subsystem 4 can be reduced to zero. The hot air subsystem 5 provides heat and assists in heat dissipation through convection heat transfer, suppressing excessively rapid temperature rise caused by the exothermic reaction of the resin crosslinking.

[0092] Once the composite material part has completed the preset heat preservation time, the curing process is considered complete. The collaborative control subsystem 7 generates a process completion signal, which can trigger an alarm signal or automatically execute subsequent operations such as depressurization, chamber opening, and mold removal.

[0093] As another implementation of this embodiment, the comprehensive state function value can also be calculated using the following weighted sum formula: , in, Ф(t) represents the comprehensive state function value at time t; T(t) represents the temperature value at time t, which is measured by temperature sensor 61; T0 represents the preset initial curing temperature; ε(t) represents the dielectric loss factor monitored in real time at time t; ε peak This indicates the maximum value of the dielectric loss factor ε(t) that has appeared during the real-time monitoring process, which is dynamically updated by the collaborative control subsystem 7 based on the real-time acquired dielectric loss factor ε(t). a and b are weighting coefficients; a>0, b>0.

[0094] This embodiment calculates the comprehensive state function value and compares it with the state function threshold Ф. th The comparison enables the identification of the core heating stage and the exothermic reaction stage. The calculation of the comprehensive state function value is not limited to the two formulas mentioned above. Those skilled in the art can use other mathematical forms to combine temperature information with dielectric property information to obtain a comprehensive state function value that reflects the combined trend of the two and shows an increasing trend in the exothermic reaction stage compared to the core heating stage. All of these can be used for the curing stage identification of this invention.

[0095] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for the synergistic curing of composite material parts, applied in a curing apparatus comprising a microwave subsystem (4), a hot air subsystem (5), and a sensing and monitoring subsystem (6), characterized in that, Includes the following steps: S1. Acquisition of internal state information: Acquire the internal state information of the composite material part monitored by the sensing and monitoring subsystem (6) in real time. The internal state information includes at least one of the following: temperature information and dielectric property information. S2. Solidification Stage Identification: Based on the internal state information obtained in step S1, a determination result is generated, wherein the determination result is any one of the following: The current curing stage of the composite material component is the core heating stage; The current curing stage of the composite material part is the exothermic reaction stage; S3, Coordinated Regulation: Based on the judgment result of step S2; During the core heating phase, the output power of the microwave subsystem (4) is made dominant. During the exothermic reaction phase, the output power of the hot air subsystem (5) is made dominant.

2. The method for co-curing composite material parts according to claim 1, characterized in that, In step S2, when the internal state information is the temperature information: If the temperature information is less than the initial curing temperature of the resin matrix in the composite material part, then the current curing stage is determined to be the core heating stage; If the temperature information is greater than or equal to the initial curing temperature, and the heating rate is greater than the preset heating rate threshold, then the current curing stage is determined to be the exothermic reaction stage.

3. The method for co-curing composite material parts according to claim 2, characterized in that, In step S2, when the temperature information is greater than or equal to the initial curing temperature and the heating rate is less than or equal to the heating rate threshold, the determination result of the core heating stage is maintained.

4. The method for co-curing composite material parts according to claim 3, characterized in that, The reinforcement in the composite material component is continuous carbon fiber.

5. The method for co-curing composite material parts according to claim 1, characterized in that, The reinforcement in the composite material component is an insulating fiber with a dielectric loss factor of less than 0.01; In step S2, when the internal state information is the dielectric characteristic information, the dielectric characteristic information is the dielectric loss factor: If the dielectric loss factor has not yet reached its peak value during the monitoring process, then the current curing stage is determined to be the core heating stage. If the dielectric loss factor reaches its peak and begins to show a continuous downward trend, then the current curing stage is determined to be the exothermic reaction stage.

6. The method for co-curing composite material parts according to claim 5, characterized in that, In step S2, when the internal state information includes both the temperature information and the dielectric property information: Calculate the comprehensive state function value based on the temperature information and the dielectric property information; If the comprehensive state function value is less than the preset state function threshold, then the current solidification stage is determined to be the core heating stage; If the comprehensive state function value is greater than or equal to the preset state function threshold, then the current solidification stage is determined to be the exothermic reaction stage.

7. The method for synergistic curing of composite material parts according to claim 6, characterized in that, The value of the integrated state function is calculated using the following formula: The comprehensive state function value is calculated using the following formula: ,in, Ф(t) represents the comprehensive state function value at time t; ε(t) represents the dielectric loss factor monitored in real time at time t; ε ref Indicates the preset reference dielectric loss factor; m represents the exponential weight of the dielectric signal; (dT / dt)(t) represents the real-time heating rate at time t; (dT / dt) th This indicates the preset heating rate threshold. n represents the exponential weight of the heating rate.

8. The method for co-curing composite material parts according to claim 1, characterized in that, In step S3, the output power of the microwave subsystem (4) is dominant, meaning that the output power of the microwave subsystem (4) accounts for more than 60% of the total output power of the microwave subsystem (4) and the hot air subsystem (5); the output power of the hot air subsystem (5) is dominant, meaning that the output power of the hot air subsystem (5) accounts for more than 60% of the total output power of the microwave subsystem (4) and the hot air subsystem (5).

9. The method for co-curing composite material parts according to claim 1, characterized in that, During the core heating phase, step S1 is executed again to continue acquiring the internal state information.

10. A composite material co-curing system for performing a co-curing method for a composite material part as described in any one of claims 1 to 9, characterized in that, include: A sealed and pressure-bearing curing chamber (1); The microwave subsystem (4) and the hot air subsystem (5) are installed in the curing chamber (1). The sensing and monitoring subsystem (6) is configured to monitor the internal state information of the composite material part placed in the curing chamber (1) in real time; The collaborative control subsystem (7) is communicatively connected to the microwave subsystem (4), the hot air subsystem (5) and the sensing and monitoring subsystem (6), and is configured to perform the collaborative curing method for composite material parts as described in any one of claims 1 to 9.

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