A method for dynamic control of an autoclave

Abstract

The application discloses a kind of autoclave dynamic control methods, the dynamic control method is based on product temperature variation relationship and mould temperature variation relationship, real-time acquisition fluid velocity v, fluid temperature T2And fluid pressure P, and by the product temperature variation relationship formula, mould temperature variation relationship formula, product boundary condition formula and mould boundary condition formula respectively real-time obtained composite product temperature variation curve and mould temperature variation curve;And with initial composite product temperature variation curve and mould temperature variation curve deviate, by autoclave control system adjusts above-mentioned parameter, so that real-time composite product temperature variation curve and mould temperature variation curve meet the process requirement.The advantage of the present application is to expand the conventional autoclave control function, make up the influence of the temperature control lag of prior art and the defect that composite product temperature cannot be predicted, meet the new demand of composite material temperature automatic control.

Description

Technical Field

[0001] This invention relates to the field of high-quality molding technology of carbon fiber composite materials based on autoclaves, and particularly to a dynamic control method for autoclaves, especially a dynamic control method for autoclaves based on the temperature relationship between composite materials and molds. Background Technology

[0002] The selection and setting of the autoclave curing process and the precise automatic control of temperature and pressure are the main factors reflecting the performance of the autoclave equipment. This process mainly includes: pressure rise and fall control, heating stage, heat preservation stage, and cooling stage.

[0003] In conventional autoclaves, a directional circulating airflow heats and pressurizes the composite material products and molds within the vessel, causing them to solidify. A temperature difference exists between the front and rear ends of the composite material products and molds along the airflow direction during the curing process. Excessive temperature difference between the front and rear ends of the composite material during curing can lead to inconsistent performance after curing. Furthermore, process engineers aim for the overall temperature of the composite material to reach the curing temperature point as simultaneously as possible, without any overheating. The composite material itself generates heat during the curing process due to chemical reactions, further increasing the difficulty of temperature control along the length of the autoclave.

[0004] As composite products become larger, the requirements for consistent product performance control become increasingly stringent. Equipment needs to be flexible enough to accommodate additional temperature control methods and devices, and integrated with the main control system.

[0005] Current autoclaves lack mathematical models for heat transfer and pressure control, relying mainly on production experience to set fixed temperature control curves or making adjustments in subsequent stages based on the current temperatures of the composite product and mold. This fails to achieve real-time prediction and dynamic adjustment of temperature and pressure. Therefore, a future demand is for an autoclave capable of predicting temperature changes in composite products during the curing process and automatically adjusting accordingly.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] Existing autoclaves suffer from significant temperature differences between the front and rear ends of composite products during curing, preventing the overall temperature of the composite product from simultaneously reaching the curing temperature. Autoclaves cannot account for temperature changes caused by the heat generated by the chemical reaction during curing, resulting in blind spots in temperature control of the composite product. Temperature control can only be adjusted later, failing to achieve real-time prediction and dynamic automatic adjustment of temperature and pressure.

[0008] To address the aforementioned technical problems, the present invention addresses the issue of how existing technologies adjust the control system by comparing real-time temperature measurements of composite material products with the set temperature requirements of the curing process. However, this approach cannot predict whether the product's temperature change curve will meet the set temperature requirements of the composite material product's curing process. Therefore, a more intelligent and flexible control method is needed, which generates real-time temperature changes of the composite material product during the curing process and performs feedforward temperature control.

[0009] According to one aspect of this disclosure, a dynamic control method for an autoclave is provided, the dynamic control method being based on the relationship between product temperature change and mold temperature change, comprising the following steps:

[0010] Step 1: Establish the product temperature change relationship, the mold temperature change relationship, the product boundary condition formula, and the mold boundary condition formula, and store the above relationships in the autoclave control system;

[0011] The relationship between the product's temperature change and the formula is:

[0012]

[0013] The formula for mold temperature change is:

[0014]

[0015] The formula for the boundary conditions of the product is:

[0016]

[0017] The formula for mold boundary conditions is:

[0018]

[0019] In the various relationships and formulas: the effective diameter d of the autoclave, the fluid density ρ, and the fluid specific heat C p Fluid thermal conductivity λ1, fluid viscosity μ, fiber specific heat C f Specific heat of resin C r Fiber density ρ f Resin density ρ r Thermal conductivity matrix k, mold thermal conductivity λ, carbon fiber content volume fraction V f 1. Heat release Hr per unit weight of resin during curing reaction for each composite material; 2. Parameters describing the chemical kinetics of the resin: the initial coefficient A of the chemical kinetics of the resin, the activation energy ΔE of the chemical kinetics of the resin, and the order constants m and n of the chemical kinetics of the resin; 3. v, T2 and P are input parameters, where v is the fluid velocity, T2 is the fluid temperature and P is the fluid pressure.

[0020] Step 2: According to the curing process requirements, input the initial fluid velocity v, fluid temperature T2 and fluid pressure P into the autoclave control system, and obtain the initial composite material product temperature change curve and the initial mold temperature change curve respectively through the product temperature change relationship, mold temperature change relationship, product boundary condition formula and mold boundary condition formula.

[0021] Step 3: Start the autoclave control system to acquire fluid velocity v, fluid temperature T2, and fluid pressure P in real time. Then, using the aforementioned product temperature change formula, mold temperature change formula, product boundary condition formula, and mold boundary condition formula, obtain the composite material product temperature change curve and mold temperature change curve in real time, respectively. When the real-time composite material product temperature change curve and mold temperature change curve deviate from the initial composite material product temperature change curve and mold temperature change curve, adjust the fluid velocity v, fluid temperature T2, and fluid pressure P through the autoclave control system to ensure that the real-time composite material product temperature change curve and mold temperature change curve meet the process requirements.

[0022] Furthermore, the autoclave control system has a host computer and a programmable logic controller (PLC), and both the host computer and the PLC have embedded or integrated the aforementioned composite material product and mold temperature relationship coupling module; the composite material product and mold temperature relationship module stores the product temperature change relationship formula, the mold temperature change relationship formula, the product boundary condition formula, and the mold boundary condition formula.

[0023] Furthermore, it also includes an execution module that can drive the valve components and heater to regulate the fluid velocity v, fluid temperature T2, and fluid pressure P.

[0024] Furthermore, it also includes a real-time monitoring and analysis module, which is used to compare the real-time temperature change curves of the composite material product and the mold with the initial temperature change curves of the composite material product and the mold, and to obtain the deviation value or deviation range.

[0025] Furthermore, the autoclave control system is used to control the elongated cylindrical autoclave. Even further, the elongated cylindrical autoclave is at least 30m long.

[0026] Furthermore, it also includes a mathematical model calculation module, which can fit the relational expression into a curve and display the curve on the display.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0028] Technical effect

[0029] The advantage of this invention is that it expands the control function of conventional autoclaves. By predicting the temperature change curve of composite material products in real time, a feedforward control program is adopted for the control of the autoclave equipment, which has better temperature control effect, simpler operation, and more flexible curing process settings. It makes up for the influence of temperature control lag and the defect of not being able to predict the temperature of composite material products in the existing technology, and meets the new demand for automatic temperature control of composite materials. Detailed Implementation

[0030] The exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0031] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first,” “second,” and “third” are used only as markers and are not a limitation on the number of objects.

[0032] In related technologies, a dynamic control method for an autoclave is provided. This dynamic control method is based on the relationship between product temperature changes and mold temperature changes, and includes the following steps:

[0033] Step 1: Establish the product temperature change relationship, the mold temperature change relationship, the product boundary condition formula, and the mold boundary condition formula, and store the above relationships in the autoclave control system;

[0034] The relationship between the product's temperature change and the formula is:

[0035]

[0036] The formula for mold temperature change is:

[0037]

[0038] The formula for the boundary conditions of the product is:

[0039]

[0040] The formula for mold boundary conditions is:

[0041]

[0042] In the various relationships and formulas: the effective diameter d of the autoclave, the fluid density ρ, and the fluid specific heat C pFluid thermal conductivity λ1, fluid viscosity μ, fiber specific heat C f Specific heat of resin C r Fiber density ρ f Resin density ρ r Thermal conductivity matrix k, mold thermal conductivity λ, carbon fiber content volume fraction V f 1. Heat release Hr per unit weight of resin during curing reaction for each composite material; 2. Parameters describing the chemical kinetics of the resin: the initial coefficient A of the chemical kinetics of the resin, the activation energy ΔE of the chemical kinetics of the resin, and the order constants m and n of the chemical kinetics of the resin; 3. v, T2 and P are input parameters, where v is the fluid velocity, T2 is the fluid temperature and P is the fluid pressure.

[0043] Step 2: According to the curing process requirements, input the initial fluid velocity v, fluid temperature T2 and fluid pressure P into the autoclave control system, and obtain the initial composite material product temperature change curve and the initial mold temperature change curve respectively through the product temperature change relationship, mold temperature change relationship, product boundary condition formula and mold boundary condition formula.

[0044] Step 3: Start the autoclave control system to acquire fluid velocity v, fluid temperature T2, and fluid pressure P in real time. Then, using the aforementioned product temperature change formula, mold temperature change formula, product boundary condition formula, and mold boundary condition formula, obtain the composite material product temperature change curve and mold temperature change curve in real time, respectively. When the real-time composite material product temperature change curve and mold temperature change curve deviate from the initial composite material product temperature change curve and mold temperature change curve, adjust the fluid velocity v, fluid temperature T2, and fluid pressure P through the autoclave control system to ensure that the real-time composite material product temperature change curve and mold temperature change curve meet the process requirements.

[0045] The autoclave control system includes a host computer and / or a programmable logic controller (PLC). Both the host computer and the PLC embed or integrate a coupling module for the temperature relationship between the composite material product and the mold. This module stores the product temperature change formula, the mold temperature change formula, the product boundary condition formula, and the mold boundary condition formula. The host computer / PLC can set and adjust v (fluid velocity), T2 (fluid temperature), and P (fluid pressure).

[0046] It also includes an execution module, which can regulate the fluid velocity v, fluid temperature T2 and fluid pressure P through valve components and heaters.

[0047] It also includes a real-time monitoring and analysis module, which is used to compare the real-time temperature change curves of the composite material product and the mold with the initial temperature change curves of the composite material product and the mold, and to obtain the deviation value or deviation range.

[0048] The autoclave control system is used to control the elongated cylindrical autoclave. Furthermore, the elongated cylindrical autoclave is at least 30m long.

[0049] It also includes a mathematical model calculation module and a display device, wherein the mathematical model calculation module is capable of fitting the relational expression into a curve and displaying the curve on the display device.

[0050] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A dynamic control method for an autoclave, the dynamic control method being based on the relationship between product temperature change and mold temperature change, characterized in that, Includes the following steps: Step 1: Establish the product temperature change relationship, the mold temperature change relationship, the product boundary condition formula, and the mold boundary condition formula, and store the above relationships in the autoclave control system; The relationship between the product's temperature change and the formula is: The formula for mold temperature change is: The formula for the boundary conditions of the product is: The formula for mold boundary conditions is: In the various relationships and formulas: the effective diameter d of the autoclave, the fluid density ρ, and the fluid specific heat C p Fluid thermal conductivity λ1, fluid viscosity μ, fiber specific heat C f Specific heat of resin C r Fiber density ρ f Resin density ρ r Thermal conductivity matrix k, mold thermal conductivity λ, carbon fiber content volume fraction V f 1. Heat release Hr per unit weight of resin during curing reaction for each composite material; 2. Parameters describing the chemical kinetics of the resin: the initial coefficient A of the chemical kinetics of the resin, the activation energy ΔE of the chemical kinetics of the resin, and the order constants m and n of the chemical kinetics of the resin; 3. v, T2 and P are input parameters, where v is the fluid velocity, T2 is the fluid temperature and P is the fluid pressure. Step 2: According to the curing process requirements, input the initial fluid velocity v, fluid temperature T2 and fluid pressure P into the autoclave control system, and obtain the initial composite material product temperature change curve and the initial mold temperature change curve respectively through the product temperature change relationship, mold temperature change relationship, product boundary condition formula and mold boundary condition formula. Step 3: Start the autoclave control system to acquire fluid velocity v, fluid temperature T2, and fluid pressure P in real time. Then, using the aforementioned product temperature change formula, mold temperature change formula, product boundary condition formula, and mold boundary condition formula, obtain the composite material product temperature change curve and mold temperature change curve in real time, respectively. When the real-time composite material product temperature change curve and mold temperature change curve deviate from the initial composite material product temperature change curve and mold temperature change curve, adjust the fluid velocity v, fluid temperature T2, and fluid pressure P through the autoclave control system to ensure that the real-time composite material product temperature change curve and mold temperature change curve meet the process requirements.

2. The dynamic control method for an autoclave according to claim 1, characterized in that: The autoclave control system has a host computer and a programmable logic controller (PLC). Both the host computer and the PLC have embedded or integrated the composite material product and mold temperature relationship coupling module. The composite material product and mold temperature relationship module stores the product temperature change relationship formula, the mold temperature change relationship formula, the product boundary condition formula, and the mold boundary condition formula.

3. The dynamic control method for an autoclave according to claim 1, characterized in that: It also includes a dynamic correction execution module, which can drive valve components and heaters to adjust fluid velocity v, fluid temperature T2 and fluid pressure P.

4. The dynamic control method for an autoclave according to claim 1, characterized in that: It also includes a real-time monitoring and analysis module, which is used to compare the real-time temperature change curves of the composite material product and the mold with the initial temperature change curves of the composite material product and the mold, and to obtain the deviation value or deviation range.

5. The dynamic control method for an autoclave according to claim 1, characterized in that: The autoclave control system is used to control the long cylindrical autoclave.

6. The dynamic control method for an autoclave according to claim 5, characterized in that: The length of the long cylindrical autoclave is at least 30m.

7. The dynamic control method for an autoclave according to claim 1, characterized in that: It also includes a mathematical model calculation module, which can fit the relational expression into a curve and display the curve on the display.

8. The dynamic control method for an autoclave according to claim 2, characterized in that: The autoclave control system includes a human-machine interface device for initial parameter setting and real-time correction. The human-machine interface device can transmit input parameters to a host computer, a programmable logic controller (PLC), or an execution module.

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