A method and system for controlling the temperature of a towpreg based on changes in the viscosity of the towpreg

Abstract

The present application relates to the technical field of composite material automatic forming equipment design, in particular to a kind of temperature control method and system based on pre-impregnated tow viscosity variation, the control method includes: real-time acquisition laying speed;According to the laying speed collected, the best laying temperature of pre-impregnated material is calculated in real time;Collect real-time laying temperature T, combine the best laying temperature obtained by calculation, calculate temperature error E and temperature error change rate EC, then carry out fuzzy adaptive control to temperature, realize the control adjustment of laying temperature. Through the control method and system, the coordinated control of laying speed and laying temperature process parameters can be realized, which is beneficial to the optimization of process parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material automatic forming equipment design, in particular to a filament winding temperature control method and system based on pre-impregnated tow sticking temperature change. BACKGROUND

[0002] With the wide application of automatic placement forming technology in large aerospace components, in order to meet the high efficiency manufacturing of large composite structures, improving the placement speed is the most direct and effective way. The improvement of the placement speed brings many challenges to the forming process. High-speed placement requires the pre-impregnated filament to obtain a large amount of heat in a short time to realize temperature rise, and the heating device needs to quickly respond to control the heat supply to ensure that the pre-impregnated filament temperature is accurate and placed in the appropriate process window.

[0003] At present, the automatic filament winding equipment in China mainly uses hot air heating. The hot air heating system has large inertia and heat loss, low heat exchange efficiency, weak heating directionality and slow heating response, which is easy to cause adverse effects on other mechanisms of the placement head. Compared with hot air heating, infrared heating has the advantages of fast response speed, high thermal efficiency and low energy consumption, which can meet the requirements of high efficiency and low cost of large composite structure manufacturing. However, the infrared heating system is completely open and is disturbed by many external factors. Moreover, the pre-impregnated filament is in a high-speed running state. After the pre-impregnated filament is heated from the infrared heating area, its temperature changes with its own speed and the influence of the external environment when it reaches the placement point.

[0004] In order to ensure that the composite pre-impregnated filament is always in the appropriate process window for placement forming, the placement temperature of the pre-impregnated filament needs to be accurately controlled during the automatic filament winding forming process. In order to adapt to high-speed automatic placement, new efficient heating and accurate control methods need to be studied to realize the appropriate sticking of the pre-impregnated filament on the mold surface or the surface of the pre-impregnated material that has been placed, so as to ensure the forming quality of the placement layer. SUMMARY

[0005] To solve the above technical problems, the present application provides a filament winding temperature control method and system based on pre-impregnated tow sticking temperature change, which can realize the coordinated control of the placement speed and the filament winding temperature process parameters, and is beneficial to the optimization of the process parameters.

[0006] The present application is realized by adopting the following technical solutions:

[0007] A filament winding temperature control method based on pre-impregnated tow sticking temperature change, comprising the following steps:

[0008] Step S1. Real-time acquisition of placement speed;

[0009] Step S2. According to the laying speed collected in step S1, the optimal fiber placement temperature of the prepreg is calculated in real time:

[0010] F = at 2 + vt + y

[0011] In the formula, F is the adhesion of the prepreg, t is the fiber placement temperature, v is the laying speed, a is the influence factor of the fiber placement temperature, b is the influence factor of the laying speed, and y is the process parameter influence factor; wherein, according to different specifications of the prepreg, a plurality of sets of laying process parameters are set to test, and the corresponding prepreg adhesion F and the process parameter influence factors a, b and y of the prepreg of the specification are measured;

[0012] Step S3. Collecting the real-time fiber placement temperature T, combining the optimal fiber placement temperature in step S2, calculating the temperature error E and the temperature error change rate EC, and then performing fuzzy adaptive control on the temperature to realize the control and adjustment of the fiber placement temperature.

[0013] In the step S3, the fuzzy adaptive control of the temperature is specifically: the calculated temperature error E and the temperature error change rate EC are input into the fuzzy controller, and the three parameters K p , K i and K d of the PID controller are calculated, the PID controller calculates the voltage control amount according to the three parameters, and then adjusts the voltage to change the heating power, so as to realize the adjustment of the temperature.

[0014] A fiber placement temperature control system based on the adhesion temperature change of the prepreg tows, comprising:

[0015] A speed collection unit for collecting the laying speed in real time;

[0016] A data processing unit for calculating the optimal fiber placement temperature of the prepreg in real time according to the specification of the prepreg and the collected laying speed;

[0017] A temperature fuzzy control unit for collecting the fiber placement temperature in real time, and performing fuzzy adaptive control on the temperature according to the optimal fiber placement temperature calculated by the data processing unit, to realize the adjustment of the temperature.

[0018] The temperature fuzzy control unit comprises a measurement transmitter, a fuzzy controller, a PID controller, a heating device and a voltage adjusting module.

[0019] The heating device is an infrared heating lamp; the infrared heating lamp is opposite to the position of the fiber placement surface and is perpendicular to the fiber placement surface.

[0020] The infrared heating lamp is located at the middle position between the tape cutting device of the fiber placement equipment and the laying pressure roller of the fiber placement equipment.

[0021] The infrared heating lamp surface is further provided with a reflective coating, and the outside is further provided with a reflective lampshade.

[0022] The speed acquisition unit comprises an encoder.

[0023] The encoder main shaft is provided with a transition roller, which is closely combined with a laying pressure roller of the filament laying device, and the laying pressure roller rotates to drive the pre-impregnated material to move and drive the encoder main shaft to rotate.

[0024] Compared with the prior art, the beneficial effects of the present application are as follows:

[0025] 1. Based on the viscosity-temperature curve of the pre-impregnated material, when the filament laying temperature changes during the filament laying process, the corresponding bonding force of the pre-impregnated material is also different; and when the laying speed is different, the optimal bonding force required for the pre-impregnated material laying is also different, and the change of the bonding force will affect the final laying quality. In the present application, the viscosity-temperature curve characteristics of the pre-impregnated material used are different, and during the laying process, two variables, the laying speed and the filament laying temperature, are used, and the two variables are coordinated for fuzzy PID control, so that the bonding force of the pre-impregnated material during laying is always within the optimal range, and the filament laying temperature is within the appropriate range. Especially when starting, stopping and changing the laying speed, the filament laying temperature can be quickly responded, the heat supply can be controlled to ensure the pre-impregnated material temperature accurate, and the pre-impregnated material can be properly adhered to the surface, so as to ensure the forming quality of the laid layer.

[0026] Compared with the temperature change rate in the prior art, the temperature error change rate EC is used to control the temperature change in the present application, and the temperature control is more smooth and accurate.

[0027] In the present application, the influence factor beta of the laying speed, the influence factor alpha of the filament laying temperature and the process parameter influence factor gamma are introduced, which can reduce the actual influence of the error as much as possible, so as to realize efficient heating and accurate temperature control.

[0028] 2. In the present application, a mathematical calculation model of the laying process parameters and the pre-impregnated material laying quality is established, that is, F = alpha t 2 + beta vt + gamma, which can greatly reduce the number of process tests and improve work efficiency.

[0029] 3. In the present application, the surface of the infrared heating lamp is further provided with a reflective coating, and the outside is further provided with a reflective lampshade, the effective radiation boundary is distributed along the filament laying surface, and a larger area of pre-impregnated material can be heated.

[0030] 4. In the present application, the infrared heating lamp is located at the middle position between the tape cutting device and the laying pressure roller, which can greatly reduce the influence of temperature hysteresis.

[0031] 5. The encoder is used as the forming rate detection structure in the present application, which can realize high-precision detection of the forming rate. Attached Figure Description

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0033] Figure 1 This is a schematic diagram of the temperature fuzzy control system in this invention;

[0034] Figure 2 This is a schematic diagram of the fiber-laying temperature control system in this invention;

[0035] Figure 3 This is a schematic diagram of the installation structure of the velocity acquisition unit in this invention;

[0036] Marked in the image:

[0037] 1. Speed ​​acquisition unit, 2. Data processing unit, 3. Temperature fuzzy control unit, 4. Heating device, 5. Laying pressure roller, 6. Transition roller. Detailed Implementation

[0038] Example 1

[0039] As a basic embodiment of the present invention, the present invention includes a method for controlling the filament laying temperature based on the viscosity temperature change of the prepreg tow, comprising the following steps:

[0040] Step S1. Real-time acquisition of deployment speed. This embodiment does not limit the equipment or method for acquiring deployment speed, as long as the deployment speed can be acquired.

[0041] Step S2. Based on the layup speed collected in step S1, calculate the optimal fiber placement temperature of the prepreg in real time:

[0042] F=αt 2 +βvt+γ

[0043] In the formula, F represents the adhesion strength of the prepreg, t represents the fiber placement temperature, v represents the placement speed, α represents the influence factor of the fiber placement temperature, β represents the influence factor of the placement speed, and γ represents the influence factor of the process parameters. Specifically, for different specifications of prepreg, multiple sets of placement process parameters were set for testing, and the corresponding prepreg adhesion strength F and the process parameter influence factors α, β, and γ for that specification of prepreg were measured. By setting the process parameter influence factors, the impact of errors was minimized as much as possible.

[0044] Step S3. Collecting real-time laying temperature T. The present embodiment does not limit the device and method for collecting the temperature, as long as the laying temperature can be collected. In combination with the optimal laying temperature in step S2, the temperature error E and the temperature error change rate EC are calculated. The calculation method of the temperature error change rate EC is: EC=dE / dt. Finally, fuzzy adaptive control is performed on the temperature to achieve the control and adjustment of the laying temperature.

[0045] Embodiment 2

[0046] As a preferred embodiment of the present application, the present application comprises a laying temperature control method based on the viscosity-temperature change of a prepreg bundle, comprising the following steps:

[0047] Step S1. Collecting the laying speed in real time.

[0048] Step S2. Calculating the optimal laying temperature of the prepreg in real time according to the laying speed collected in step S1:

[0049] F=αt 2 +βvt+γ

[0050] In the formula, F is the bonding force of the prepreg, t is the laying temperature, v is the laying speed, α is the influence factor of the laying temperature, β is the influence factor of the laying speed, and γ is the process parameter influence factor. According to different specifications of the prepreg, a plurality of sets of laying process parameters are set to perform tests, and the corresponding prepreg bonding force F and the process parameter influence factors α, β and γ of the prepreg of the specification are measured.

[0051] Step S3. Collecting the real-time laying temperature T, calculating the temperature error E and the temperature error change rate EC in combination with the optimal laying temperature in step S2, and performing fuzzy adaptive control on the temperature. Specifically, the temperature error E and the temperature error change rate EC calculated are input into a fuzzy controller to calculate three parameters K p , K i and K d of a PID controller, and the PID controller calculates a voltage control amount according to the three parameters, and then adjusts the voltage to change the heating power, so as to achieve the adjustment of the temperature.

[0052] Embodiment 3

[0053] As another preferred embodiment of the present application, the present application comprises a laying temperature control system based on the viscosity-temperature change of a prepreg bundle, comprising:

[0054] A speed collecting unit 1 for collecting the laying speed in real time. The speed collecting unit 1 can be a speed sensor or an encoder.

[0055] The data processing unit 2 is configured to calculate the optimal fiber placement temperature of the prepreg according to the specification of the prepreg and the collected fiber placement speed. Specifically, a data processing model about the change of the fiber placement temperature and the change of the fiber placement speed can be established, and the optimal fiber placement process parameter relationship of the prepreg can be obtained through the data processing model. In the data processing model, the process parameters of the prepreg, the fiber placement temperature t and the fiber placement speed v are included; the influence factors of the fiber placement temperature α, the influence factors of the fiber placement speed β and the process parameter influence factors γ are included; and the adhesive force F of the prepreg is included. Further, the data processing model can be as follows:

[0056] F = αt 2 + βvt + γ.

[0057] According to different specifications of the prepreg, a plurality of groups of fiber placement process parameters are set for testing, and the corresponding adhesive force of the prepreg is measured, so that the process parameter influence factors of the prepreg of the specification can be obtained. The process parameter influence factors α, β and γ of the prepreg are obtained through the pre-set test, and then the optimal fiber placement process parameters of the prepreg can be reversely calculated according to the optimal adhesive force F of the prepreg and the data processing model, so that the optimal fiber placement temperature of the prepreg can be obtained when the fiber placement speed is determined.

[0058] The temperature fuzzy control unit 3 is configured to collect the fiber placement temperature in real time, and to perform fuzzy adaptive control on the temperature according to the optimal fiber placement temperature calculated by the data processing unit 2, so as to realize the adjustment of the temperature. The temperature fuzzy control unit 3 can include a measurement transmitter, a fuzzy controller, a PID controller, a heating device 4 and a voltage regulating module. Specifically, the measurement transmitter is used to obtain the real-time fiber placement temperature T of the prepreg, and the fiber placement temperature signal is converted into a signal that can be recognized by the controller. Then, the real-time fiber placement temperature is subtracted from the optimal fiber placement temperature to obtain the temperature error E and the temperature error change rate EC = dE / dt. Then, the fuzzy controller and the PID controller are used to coordinate the control, the temperature error and the error change rate are input into the fuzzy controller, and three parameters K p , K i and K d of the PID controller are obtained. The PID controller calculates the voltage control amount according to the obtained parameters, and inputs the voltage control amount into the voltage regulating module. The voltage regulating module changes the output power of the heating device 4, so as to realize the adjustment of the temperature.

[0059] Specifically, the heating device 4 can be fixed on the winding head of the fiber placement device by a mounting bracket, and is perpendicular to the winding surface during the winding process and moves along the tangent direction of the surface, so that the position of the heating device 4 relative to the winding surface remains unchanged. When the speed acquisition unit 1 is an encoder, the encoder is integrated on the winding head of the fiber placement device, and the transition roller 6 fixed on the main shaft of the encoder is tightly attached to the fiber placement pressure roller 5.

[0060] Embodiment 4

[0061] As the best mode of the present application, the present application comprises a fiber placement temperature control system based on the change of the tackiness of the prepreg fiber bundle, referring to the attached drawings of the specification Figure 2 , comprising a speed acquisition unit 1, a data processing unit 2 and a temperature fuzzy control unit 3.

[0062] The speed acquisition unit 1 can adopt a small encoder, referring to the attached drawings of the specification Figure 3 , and the transition roller 6 fixed on the encoder main shaft is closely attached to the placement pressure roller 5 of the fiber placement device by a support. During the molding process, the placement pressure roller 5 rotates to drive the prepreg to move, and the encoder main shaft also rotates. Through the conversion of the corresponding size, the high-precision detection of the molding rate can be realized.

[0063] The data processing unit 2 can establish a data processing model about the change of the fiber placement temperature and the change of the placement speed. The optimal relationship of the placement process parameters of the prepreg can be obtained through the calculation of the data processing model. In the data processing model, the placement process parameters of the prepreg include the fiber placement temperature t and the placement speed v; the influence factors of the fiber placement temperature α, the placement speed β and the process parameter γ; and the bonding force F of the prepreg. The relationship of the placement process parameters in the data processing model is as follows:

[0064] F = αt 2 + βvt + γ.

[0065] According to different specifications of the prepreg, a plurality of placement process parameters are set for testing, and the corresponding bonding force of the prepreg is measured to obtain the process parameter influence factor of the prepreg of the specification. In this embodiment, according to a certain predetermined specification of the prepreg, three groups of placement process parameters are set for testing, i.e. three different fiber placement temperatures t1, t2 , t3 and placement speeds v1, v2, v3, the performance index test of the placement quality of the prepreg is performed, and the corresponding bonding force F1, F2, F3 of the prepreg is measured:

[0066] F1 = αt1 2 + βv1t1 + γ;

[0067] F2 = αt2 2 + βv2t2 + γ;

[0068] F3 = αt3 2 + βv3t3 + γ.

[0069] According to the above three groups of equations, the optimal process parameter influence factors α0, β0 and γ0 of the prepreg of the specification can be obtained; and according to the optimal bonding force Fz of the prepreg of the specification, the following formula can be obtained:

[0070] F z = α0t 2 + β0vt + γ0.

[0071] When the laying speed is determined, the optimal fiber placement temperature of the prepreg is obtained.

[0072] The temperature fuzzy control unit 3 comprises a measurement transmitter, a fuzzy controller, a PID controller, a heating device 4 and a voltage regulating module. The measurement transmitter comprises a temperature sensor and a transmitter, which can obtain the real-time fiber placement temperature T of the prepreg, convert the fiber placement temperature signal into a signal recognizable by the controller, and then obtain the temperature error E and the temperature error change rate EC by subtracting the optimal fiber placement temperature calculated by the data processing unit 2 from the real-time fiber placement temperature. The calculation method of the temperature error change rate EC is: EC = dE / dt. Then, the fuzzy controller and the PID controller are used for coordinated control, the temperature error and the error change rate are input into the fuzzy controller, and the three parameters K p , K i and K d of the PID controller are obtained. The PID controller will calculate the voltage control amount according to the obtained parameters, and input the voltage control amount into the voltage regulating module. The voltage regulating module calculates and outputs an appropriate analog voltage according to the pulse signal output by the PID controller in real time, so as to change the output power of the heating device 4, thereby realizing the adjustment of the temperature.

[0073] The heating device 4 is an infrared heating lamp. The infrared heating lamp is fixed by a mounting bracket in the advancing direction of the laying roller 5 of the fiber placement device, and is located at the middle position between the tape cutting device of the fiber placement device and the laying roller 5 of the fiber placement device. During the fiber placement process, the infrared heating lamp is perpendicular to the surface of the tape, and the position of the infrared heating lamp relative to the surface of the fiber placement is kept unchanged. The surface of the infrared heating lamp is also provided with a reflective coating, and the outside is also provided with a reflector lampshade. The effective radiation boundary is distributed along the surface of the fiber placement, and a larger area of the mold surface can be heated.

[0074] A fiber placement temperature control method based on the viscosity-temperature change of the prepreg tows can be realized by using the above control system, and specifically comprises the following steps:

[0075] Step S1. Real-time acquisition of the laying speed by using the speed acquisition unit 1.

[0076] Step S2. Real-time calculation of the optimal fiber placement temperature of the prepreg by the data processing unit 2 according to the laying speed acquired in step S1:

[0077] F = α0t 2 + β0vt + γ0.

[0078] In the formula, F is the adhesive force of the prepreg, t is the laying temperature, v is the laying speed, a is the laying temperature influence factor, b is the laying speed influence factor, and g is the process parameter influence factor. Since the prepregs used are different, their adhesive temperature curve characteristics are also different, and the adhesive force F of the corresponding specification prepreg and the process parameter influence factors a, b, and g of the specification prepreg are determined in advance through experiments.

[0079] Step S3. Refer to the description of the accompanying drawings Figure 1 , the real-time laying temperature T is collected, the temperature error E and the temperature error change rate EC are calculated in combination with the optimal laying temperature in step S2, and the calculated temperature error E and temperature error change rate EC are input into the fuzzy controller.

[0080] Further, under a large error |E|, a larger K p and a smaller K d are selected, at this time the response speed is rapid, and K i is taken as 0 to achieve the effect of limiting integration and prevent system overshoot. When the error |E| and the error change rate |EC| are moderate, a smaller K p and a smaller K d are selected, and the value of K i is moderate. Under a small error |E|, a larger K p and K i are selected to improve the stability of the system, when the error change rate |EC| is low, K d can take a larger value, and when the error change rate is large, K d takes a smaller value.

[0081] Further, the three parameters K p , K i , and K d of the PID controller are calculated, the PID controller calculates the voltage control amount according to the three parameters obtained, and the voltage control amount is input into the voltage adjustment module, the voltage adjustment module calculates and outputs an appropriate analog voltage to the heating device 4, so as to adjust the power of the heating device 4 and realize temperature adjustment.

[0082] Specifically, the power adjustment of the heating device 4 is realized through the voltage adjustment module, a program describing the relationship between the laying speed and the infrared heating lamp power change is written in the control unit according to the dynamic temperature control equation, an appropriate analog voltage is calculated and output according to the real-time pulse signal input by the encoder, so as to adjust the output power of the heating lamp and realize real-time adjustment of the heating surface temperature.

[0083] As described above, after reading the present application document, other various corresponding transformation schemes made by ordinary skilled in the art without creative mental labor according to the technical scheme and technical concept of the present application all belong to the scope protected by the present application.

Claims

1. A method of controlling the temperature of a filament based on the change in viscosity of a pre-impregnated tow, characterized by: The method comprises the following steps: Step S1. Collecting the laying speed in real time; Step S2. Calculating the optimal fiber placement temperature of the prepreg in real time according to the laying speed collected in step S1: In the formula, F is the adhesion of the prepreg, t is the fiber placement temperature, v is the laying speed, a is the influence factor of the fiber placement temperature, b is the influence factor of the laying speed, and g is the process parameter influence factor; wherein, according to different specifications of the prepreg, a plurality of sets of laying process parameters are set to test the corresponding prepreg adhesion F and the process parameter influence factors a, b and g of the prepreg of the specification; Step S3. Collecting the real-time fiber placement temperature T, combining the optimal fiber placement temperature in step S2, calculating the temperature error E and the temperature error change rate EC, and then performing fuzzy adaptive control on the temperature to realize the control and adjustment of the fiber placement temperature.

2. The method of controlling the temperature of a filament based on the change in viscosity of the filament according to claim 1, wherein: The step S3 is fuzzy self-adaptive control of temperature, specifically: input the calculated temperature error E and temperature error change rate EC into a fuzzy controller, calculate three parameters K p , K i and K d of a PID controller, the PID controller calculates a voltage control amount according to the three parameters, and changes the heating power through voltage adjustment, so as to realize temperature regulation.

3. A yarn-laying temperature control system based on the viscosity temperature variation of pre-impregnated yarn bundles, characterized in that: It comprises: a speed collection unit (1) for collecting the laying speed in real time; a data processing unit (2) for calculating the optimal fiber placement temperature of the prepreg in real time according to the specification of the prepreg and the collected laying speed: In the formula, F is the bonding force of the prepreg, t is the filament winding temperature, v is the laying speed, a is the influence factor of the filament winding temperature, β is the influence factor of the laying speed, and γ is the process parameter influence factor; wherein, according to different specifications of the prepreg, a plurality of groups of laying process parameters are set to perform tests, and the corresponding prepreg bonding force F and the process parameter influence factors a, β and γ of the specification of the prepreg are measured. a temperature fuzzy control unit (3) for collecting the fiber placement temperature in real time and performing fuzzy adaptive control on the temperature according to the optimal fiber placement temperature calculated by the data processing unit (2) to realize the adjustment of the temperature.

4. The system for controlling the temperature of the filament based on the change of the viscosity of the pre-impregnated filament according to claim 3, wherein: The temperature fuzzy control unit (3) comprises a measurement transmitter, a fuzzy controller, a PID controller, a heating device (4) and a pressure regulating module.

5. A system for controlling the temperature of a filament based on changes in the viscosity of the filament according to claim 4, wherein: The heating device (4) is an infrared heating lamp; the infrared heating lamp is opposite to the position of the fiber placement surface and is perpendicular to the fiber placement surface.

6. A system for controlling the temperature of a filament based on changes in the viscosity of the filament according to claim 4, wherein: The infrared heating lamp is located at the middle position between the tape cutting device of the fiber placement equipment and the laying pressure roller (5) of the fiber placement equipment.

7. A system for controlling the temperature of a filament based on changes in the viscosity of the filament according to claim 6, wherein: The surface of the infrared heating lamp is further provided with a reflective coating, and the outside is further provided with a reflective lampshade.

8. A system for controlling the temperature of a filament based on changes in the viscosity of the filament according to claim 4, wherein: The speed collection unit (1) comprises an encoder.

9. A system for controlling the temperature of a filament based on changes in the viscosity of a pre-impregnated tow as recited in claim 8, wherein: The encoder main shaft is provided with a transition roller (6), the transition roller (6) is closely attached to the laying pressure roller (5) of the fiber placement equipment, the laying pressure roller (5) rotates to drive the prepreg to move, and the encoder main shaft rotates.

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