Vacuum infusion cyclic extrusion pressure control device and method based on double-layer linear algorithm

Abstract

The invention discloses a vacuum infusion cyclic extrusion pressure control device and method based on a double-layer linear algorithm, and belongs to the technical field of composite material manufacturing, the device comprises double sets of independent hardware systems, a double-pipeline control system and a pressure control box; the method comprises a pressure control method and a compaction rate control method. The compaction rate control method comprises the steps that in the cyclic extrusion process, the compaction rate is accurately controlled by adjusting the opening proportion of a vacuum electromagnetic valve of a second pipeline of the control device, and a double-layer linear algorithm is adopted; the pressure control method adopts segmented pressure control, comprises high-pressure section control and low-pressure section control, and is controlled by a first pipeline or two pipelines of the control device together. The pressure control precision reaches + / -0.1 kPa, and the compaction rate control precision is within + / -6%; the control precision can be kept within the atmospheric pressure change range of 97.5-102.5 kPa, and the system adapts to different geographical and meteorological conditions; the full-range control from 0.5 kPa to atmospheric pressure and the compaction rate control from 1 kPa / s to 5.5 kPa / s can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material manufacturing, and in particular relates to a vacuum introduction cycle extrusion pressure control device and method based on a double-layer linear algorithm. Background Art

[0002] Vacuum infusion is a composite material manufacturing process widely used in wind power, marine, aviation, and other fields. The process controls vacuum pressure to ensure a uniform flow of resin into a fiber preform. Once the resin solidifies, the resulting composite product is obtained. Therefore, pressure control is a key technology in vacuum infusion.

[0003] In recent years, researchers have developed a cyclic extrusion vacuum infusion process to improve the fiber volume content and mechanical properties of composite products. This process, which repeatedly varies the vacuum pressure before injection, cyclically extrudes the reinforcement material, effectively reducing porosity and increasing the fiber volume fraction. However, this cyclic extrusion process places higher demands on the precision and stability of pressure control.

[0004] In traditional vacuum infusion processes, pressure control relies primarily on manually adjusting vacuum valves and using mechanical vacuum regulators, making it difficult to achieve precise pressure control and stable compaction rate control. Specifically, these issues exist: 1. Traditional pressure control methods have low precision and cannot achieve precise control at the 0.1 kPa level, resulting in unstable quality of composite products. 2. The compaction rate cannot be precisely controlled, making it difficult to maintain a stable compaction rate during the cyclic extrusion process, which affects the fiber volume fraction. 3. The pressure control system has a low level of integration, making it difficult to apply to industrial production. 4. Existing control systems cannot adapt to the impact of atmospheric pressure changes on the compaction rate, and control accuracy fluctuates with changing environmental conditions.

[0005] Existing technologies, such as CN 115056509 A, "A Method for Manufacturing Composite Materials Using a Vacuum Infusion Process," and CN 100548644C, "Controlled Atmospheric Pressure Resin Infusion Method," describe a pressure-controlled vacuum infusion method but fail to elaborate on the integrated design of the pressure control device and the automated control method. Related literature, such as [Wang et al., "An Automated Vacuum Infusion Process for Manufacturing High-Quality Fiber-Reinforced Composites," 2023], describes an automated vacuum infusion workstation but does not provide a specific pressure control solution. Summary of the Invention

[0006] This invention aims to address the technical challenges of achieving high-precision pressure control and adjustable compaction rate control in vacuum infusion processes, specifically addressing the inability of existing control systems to adapt to the impact of atmospheric pressure variations on compaction rate control accuracy. To this end, the present invention provides a vacuum infusion cyclic extrusion pressure control device and method based on a double-layer linear algorithm. This double-layer linear control algorithm achieves adaptive control within the atmospheric pressure range, ensuring precise compaction rate control.

[0007] The technical solution adopted by the present invention is: A vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm includes two independent hardware systems, a dual-pipeline control system and a pressure control box; the two independent hardware systems include a filling barrel system and a resin collector system, the filling barrel system and the resin collector system are respectively controlled by the dual-pipeline control system, and the pressure control box controls the two independent hardware systems and the dual-pipeline control system.

[0008] A vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm, including a pressure control method and a compaction rate control method; The compaction rate control method is as follows: in the cyclic extrusion process, the compaction rate is precisely controlled by adjusting the opening ratio of the vacuum solenoid valve of the second pipeline of the control device, and a double-layer linear algorithm is used; The pressure control method adopts segmented pressure control, including high-pressure segment control and low-pressure segment control, which is controlled by the first pipeline of the control device or controlled by two pipelines together.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved control accuracy: The pressure control accuracy of the present invention reaches ±0.1kPa, and the compaction rate control accuracy is within ±6%; 2. Atmospheric pressure adaptation: The present invention can maintain control accuracy within the atmospheric pressure range of 97.5-102.5kPa and adapt to different geographical and meteorological conditions; 3. Wide range and precise control: The present invention can achieve full range control from 0.5kPa to atmospheric pressure and compaction rate control from 1-5.5kPa / s; 4. Highly integrated system: All control components of the present invention are integrated into a single control box, which is convenient for industrial application; 5. Independent dual-channel control: The glue injection and glue discharge pressures of the present invention are independently controlled, expanding the adjustment range of process parameters; 6. Algorithm innovation: The present invention adopts a double-layer linear control algorithm with low computational complexity and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of the exterior of the pressure control box of the present invention; Figure 2 is a system architecture diagram of the pressure control device of the present invention; Among them: 101, pressure control box front panel; 102, flange socket aviation plug 1; 103, flange socket aviation plug 2; 104, communication serial port; 105, pressure control box rear panel; 106, three-core power cord plug and socket; 107, pressure control box left panel; 108, pneumatic bulkhead connector 3; 109, pneumatic bulkhead connector 1; 110, pressure control box right panel; 111, pneumatic bulkhead connector 2; 112, pneumatic bulkhead connector 4; 201, pressure control box; 202, terminal block group; 203, 24V switching power supply; 204, controller; 205, solid-state relay module; 206, pneumatic three-way connector ;207, vacuum solenoid valve three; 208, vacuum proportional valve two; 209, vacuum solenoid valve four; 210, pneumatic three-way connector four; 211, vacuum pump two; 212, pneumatic three-way connector one; 213, vacuum solenoid valve one; 214, vacuum proportional valve one; 215, vacuum solenoid valve two; 216, pneumatic three-way connector two; 217, vacuum pump one; 218, upper computer; 219, injection barrel; 220, absolute pressure sensor one; 221, feed pipe; 222, injection control valve; 223, mold; 224, vacuum layer; 225, discharge pipe; 226, resin collector; 227, absolute pressure sensor two. DETAILED DESCRIPTION

[0011] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0012] Composites manufacturing related terms: Vacuum Infusion Process: A low-cost composite material preparation process that uses vacuum pressure differential to drive liquid resin to infiltrate reinforcing materials. It is widely used in aviation, navigation, wind power and other fields.

[0013] Cyclic extrusion vacuum infusion: A process in which the reinforcing material or consumable is cyclically extruded by repeatedly changing the vacuum pressure before injection to increase the fiber volume content and reduce the porosity.

[0014] Compaction Pressure: It is defined as the difference between atmospheric pressure and the pressure inside the vacuum bag, that is, P_compaction = P_atmosphere - P_vacuum bag.

[0015] Compaction Rate: The rate of change of compaction pressure per unit time, defined as R = (P_max- P_min) / t_compact, where P_max is the maximum compaction pressure, P_min is the minimum compaction pressure, and t_compact is the compaction duration.

[0016] Double-layer linear control algorithm: This invention's original control method, the first layer is the atmospheric pressure-opening ratio linear regression under each compaction rate, and the second layer is the linear interpolation between different compaction rates.

[0017] Atmospheric pressure adaptive control: a technical method that automatically adjusts the solenoid valve opening ratio according to real-time atmospheric pressure changes to ensure the accuracy of compaction rate control.

[0018] Consumables: Auxiliary materials used in the vacuum infusion process, such as release cloth, guide mesh, vacuum bag, etc.

[0019] Cyclic extrusion: By repeatedly changing the pressure in the vacuum bag, the reinforcement material or consumable is compacted to increase the fiber volume content.

[0020] Injection pressure: the absolute pressure in the injection barrel.

[0021] Glue discharge pressure: the absolute pressure inside the vacuum bag.

[0022] Below atmospheric pressure: The injection pressure or discharge pressure is lower than the local atmospheric pressure.

[0023] Vacuum proportional valve: An automatic regulating valve that outputs the corresponding vacuum pressure according to the input voltage signal. The output pressure is linearly related to the input signal.

[0024] Vacuum solenoid valve: A vacuum valve that controls the switch through electromagnetic force. This invention adopts the normally closed type.

[0025] PID controller: Proportional-Integral-Derivative controller, which achieves precise control through a combination of proportional, integral, and differential control functions.

[0026] Dual-line control: Two independent vacuum lines are used to control different pressure ranges, expanding the control range and improving control accuracy.

[0027] The present invention aims to achieve high-precision pressure control and adjustable compaction rate control.

[0028] The technical problems solved by the present invention specifically include: How to achieve pressure control with 0.1 kPa accuracy? How to achieve adjustable compaction rate control in the range of 1 kPa / s to 5.5 kPa / s; How to achieve independent and precise control of injection and discharge pressure; How to integrate all pressure control components into one control box to achieve system integration and automated control; How to solve the problem of how atmospheric pressure changes affect the accuracy of compaction rate control.

[0029] like Figure 1 、 Figure 2 As shown, the present invention provides a vacuum introduction cycle extrusion pressure control device based on a double-layer linear algorithm, including two sets of independent hardware systems, a dual-pipeline control system and a pressure control box 201; the two sets of independent hardware systems include a filling barrel system and a resin collector system, and the filling barrel system and the resin collector system are respectively controlled by the dual-pipeline control system, and the pressure control box 201 controls the two sets of independent hardware systems and the dual-pipeline control system.

[0030] The filling barrel system includes a 10L stainless steel container filling barrel 219, a vacuum pump 217 (flow rate 4.8m³ / h, final pressure 0.2kPa), and an absolute pressure sensor 220 (accuracy ±0.1kPa). The filling barrel 219 and the vacuum pump 217 are connected by a dual-pipeline control system, and the absolute pressure sensor 220 is installed on the filling barrel 219. Resin trap system: includes a 2L stainless steel container resin trap 226, a vacuum pump 211 (flow rate 4.8m³ / h, final pressure 0.2kPa), and an absolute pressure sensor 227 (accuracy ±0.1kPa). The resin trap 226 and the vacuum pump 211 are connected by a dual-pipeline control system, and the absolute pressure sensor 227 is installed in the resin trap 227. Since the lowest output vacuum pressure of commercially available vacuum proportional valves is usually -80 kPa, while atmospheric pressure is approximately 100 kPa, resin degassing is usually performed at an absolute pressure of 0.5 kPa or below. Therefore, vacuum proportional valves alone cannot meet the process requirements of vacuum infusion. The injection pressure and the discharge pressure are each controlled by two vacuum lines: Dual-line control system, including two independent vacuum lines: The first line is equipped with a vacuum solenoid valve and a vacuum proportional valve to control the pressure range from atmospheric pressure to 79 kPa below atmospheric pressure; The second line is equipped with a vacuum solenoid valve, which works in conjunction with the first line to control the pressure range from 79 kPa below atmospheric pressure to 0.5 kPa absolute pressure; The dual-pipeline control system between the injection barrel 219 and the vacuum pump 217 is: The air pipe of the filling barrel 219 is connected to the pneumatic three-way connector 1 212 in the pressure control box 201 through the pneumatic partition connector 109 on the pressure control box 201, and the first pipeline and the second pipeline are respectively connected between the pneumatic three-way connector 212 and the pneumatic three-way connector 216; the first pipeline is equipped with a vacuum solenoid valve 1 213 and a vacuum proportional valve 1 214, and the second pipeline is equipped with a vacuum solenoid valve 215, and the pneumatic three-way connector 216 is connected to the vacuum pump 1 217 through the pneumatic partition connector 2 111 on the pressure control box 201.

[0031] The dual-pipeline control system between the resin trap 226 and the vacuum pump 211 is: The air pipe of the resin collector 22 is connected to the pneumatic three-way connector 206 in the pressure control box 201 through the pneumatic partition connector 3 108 on the pressure control box 201, and the first pipeline and the second pipeline are respectively connected between the pneumatic three-way connector 206 and the pneumatic three-way connector 210; the first pipeline is equipped with a vacuum solenoid valve 3 207 and a vacuum proportional valve 2 208, and the second pipeline is equipped with a vacuum solenoid valve 4 209, and the pneumatic three-way connector 4 210 is connected to the vacuum pump 2 211 through the pneumatic partition connector 4 112 on the pressure control box 201.

[0032] A vacuum ply 224 is placed on the mold 223 . The vacuum ply 224 is connected to the resin collector 226 via a discharge pipe 225 . The vacuum ply 224 is connected to the injection barrel 219 via a feed pipe 221 . An injection control valve 222 is provided on the feed pipe 221 .

[0033] The pressure control box 201 is provided with a controller 204, a solid-state relay module 205, a 24V switching power supply 203, a standardized interface, two vacuum proportional valves and four vacuum solenoid valves; wherein, The two vacuum proportional valves are vacuum proportional valve 208 and vacuum proportional valve 1 214: the output pressure range is -80kPa to 0kPa, and the accuracy is ±0.5kPa; The four vacuum solenoid valves are vacuum solenoid valve 3 207, vacuum solenoid valve 4 209, vacuum solenoid valve 1 213, and vacuum solenoid valve 2 215: normally closed, with a response time of ≤50ms; Solid-state relay module 205: 4-way module, controls four solenoid valve switches; 24V switching power supply 203: output power 120W, connected to the terminal block 202, controller 204, and solid-state relay module 205; Controller 204: PLC or FPGA controller, with 16 digital outputs and 8 analog outputs; connected to solid-state relay module 205 and two vacuum proportional valves.

[0034] Standardized interfaces: including flange socket aviation plug 1 102, flange socket aviation plug 2 103, communication serial port 104, three-core power cord plug and socket 106, pneumatic bulkhead connector 1 109, pneumatic bulkhead connector 2 111, pneumatic bulkhead connector 3 108, pneumatic bulkhead connector 4 112; wherein, the communication serial port 104 is used to connect the host computer 218 and the controller 204, The flange socket aviation plug 102 is used to connect the absolute pressure sensor 220 and the controller 204. The flange socket aviation plug 2 103 is used to connect the absolute pressure sensor 227 and the controller 204. The three-core power cord plug and socket 106 is connected to the connection terminal set 202 .

[0035] The present invention provides a vacuum introduction cycle extrusion pressure control method based on a double-layer linear algorithm, including a pressure control method and a compaction rate control method; The compaction rate control method is as follows: in the cyclic extrusion process, the compaction rate is precisely controlled by adjusting the opening ratio of the vacuum solenoid valve of the second pipeline of the control device, and a double-layer linear algorithm is used; The pressure control method adopts segmented pressure control, including high-pressure segment control and low-pressure segment control, which is controlled by the first pipeline of the control device or controlled by two pipelines together.

[0036] High pressure section control (atmospheric pressure to 79 kPa below atmospheric pressure), When the pressure setting value is from atmospheric pressure to 79 kPa below atmospheric pressure, the pressure is controlled by the first pipeline of the control device, and the vacuum solenoid valve of the second pipeline is normally closed. The control signal consists of a 0-5V analog signal sent to the vacuum proportional valve, generated by a PID controller with parameters: proportional gain Kc = 0.035, integral time Ti = 0.07, and derivative time Td = 0. The theoretical relationship between output pressure and input signal is: y = (x / 80) × 5, where x is the atmospheric pressure minus the target pressure, and y is the theoretical value of the input control signal. The control signal range is limited to an absolute deviation of 0.1 V from the theoretical value; if it exceeds this range, it is set to 5 V or 0 V.

[0037] A 0 / 5 V analog signal is sent to solid-state relay module 205 to control the opening and closing of the vacuum solenoid valve. When the absolute difference between the measured pressure and the set pressure is greater than 0.5 kPa, the vacuum solenoid valve is normally open; otherwise, it opens for 0.5 seconds per second. Specifically, when the pressure set point is between atmospheric pressure and 1 kPa below atmospheric pressure, the vacuum proportional valve input signal is 0 V, and the vacuum solenoid valve is normally open.

[0038] Low pressure section control (79 kPa to 0.5 kPa below atmospheric pressure): When the pressure setting value is 79 kPa below atmospheric pressure to 0.5 kPa absolute pressure, the pressure is controlled by two pipelines. The control method is: The input signal of the vacuum proportional valve is set to a fixed value: 5 V when the pressure setting value is less than 17 kPa, otherwise it is 4.5 V.

[0039] The opening ratio of the vacuum solenoid valve is determined by the real-time measured pressure: When the measured value exceeds the set value, the solenoid valve in the first line is closed, while the solenoid valve in the second line is periodically opened. If the measured value exceeds the set value by a certain amount (pressure setting value / 0.8, rounded to one decimal place), the solenoid valve in the second line is opened. Otherwise, the opening ratio is y = max(0.05, min(1, (25-x) / 22)), where x is the pressure setting value and y is the opening ratio, rounded to three decimal places. The solenoid valve opens at this ratio every two seconds.

[0040] When the measured value is less than the set value, the solenoid valve of the second pipeline is normally closed, and the solenoid valve of the first pipeline is opened according to y = max(0.05, min(0.5, 0.05 + 0.0225(x-5))). The solenoid valve is opened once every two seconds according to this ratio.

[0041] When the measured value is equal to the set value, the solenoid valve of the first pipeline is closed and the solenoid valve of the second pipeline is opened at a ratio of 0.05.

[0042] For the three solenoid valve opening ratios in these three situations, the ratios are corrected based on the past three pressure measurements: When the measured value is greater than the set value, if the opening ratio is too high (i.e., the pressure measurement is lower than the set value after adjustment), the set value is reduced by 0.01 each time, with a minimum of 0.05. When the measured value is less than the set value, if the opening ratio is too high (i.e., the pressure measurement is higher than the set value after adjustment), the set value is reduced by 0.01 each time, with a minimum of 0.05. When the measured value is equal to the set value, if the opening ratio is too high (i.e., the pressure measurement is lower than the set value after adjustment), the set value is reduced to 0.05 seconds per n seconds, with n gradually increasing. If the opening ratio is too low (i.e., the pressure measurement is higher than the set value after adjustment), the opening ratio is increased by 0.01 each time, with a maximum of 1.

[0043] During the cyclic extrusion process, precise control of the compaction rate is achieved by adjusting the opening ratio of the vacuum solenoid valve in the second pipeline. The compaction rate is defined as the difference between the maximum compaction pressure and the minimum compaction pressure divided by the compaction duration, that is, R = (Pmax−Pmin) / tcompacted. The maximum compaction pressure is 97.6 kPa, and the minimum compaction pressure is 0 kPa. It should be noted that the minimum atmospheric pressure measured in the inventor's location is 98 kPa. To improve the repeatability of the cyclic extrusion, the maximum compaction pressure is set to a fixed value, that is, 0.4 kPa lower than the minimum atmospheric pressure.

[0044] In the following vacuum system, the vacuum valve opening ratio corresponding to different compaction rates at three atmospheric pressures was measured: Piping system specifications: Injection hose: outer diameter 6mm, inner diameter 4mm, polyurethane material Outlet hose: outer diameter 6mm, inner diameter 4mm, polyurethane material Other pneumatic pipes: outer diameter 10mm, inner diameter 6.5mm, polyurethane material All pipe connections use quick-connect connectors to ensure sealing performance Vacuum pump specifications: Flow rate: 4.8 m^3 / h, final pressure: 0.2 kPa.

[0045] Table 1: Comparison of compaction rate and solenoid valve opening ratio under different atmospheric pressures

[0046] The present invention adopts a double-layer linear algorithm to achieve precise control of the compaction rate: the first layer is the atmospheric pressure-opening ratio linear regression under each compaction rate; the second layer is the linear interpolation between different compaction rates.

[0047] First layer: Compaction rate regression line is established. For each standard compaction rate value, the atmospheric pressure-opening ratio regression equation is established: For each compaction rate value in Table 1, a linear regression is performed using the opening ratio data under three atmospheric pressure conditions to establish a control line for that compaction rate: f_i = a_i P_atm + b_i Among them, f_i is the opening ratio under the compaction rate R_i, P_atm is the current atmospheric pressure, and a_i and b_i are regression coefficients.

[0048] Regression parameter table of experimental calibration: Compaction rate (kPa / s) Slope a_i Intercept b_i Correlation coefficient R² Regression equation 1.0 -0.0287 2.956 0.999 f = -0.0287P + 2.956 1.5 -0.0313 3.284 0.999 f = -0.0313P + 3.284 2.0 -0.0373 3.946 0.999 f = -0.0373P + 3.946 2.5 -0.0467 4.955 0.999 f = -0.0467P + 4.955 3.0 -0.0600 6.360 0.999 f = -0.0600P + 6.360 3.5 -0.0760 8.033 0.999 f = -0.0760P + 8.033 4.0 -0.0960 10.087 0.999 f = -0.0960P + 10.087 4.5 -0.1200 12.587 0.999 f = -0.1200P + 12.587 5.0 -0.1473 15.395 0.999 f = -0.1473P + 15.395 5.5 -0.1780 18.552 0.999 f = -0.1780P + 18.552 Table 2: Regression parameters under various compaction rates

[0049] Second layer: target compaction rate interpolation algorithm For any target compaction rate R_target (1.0-5.5 kPa / s), perform the following steps: Step 1: Determine the adjacent compaction rate and find the adjacent compaction rate value that satisfies Rlower ≤ Rtarget ≤ Rupper; Step 2: Calculate the interpolation weight w = (R_target - R_lower) / (R_upper - R_lower); Step 3: Regression parameter interpolation a_target = a_lower + w × (a_upper - a_lower)b_target = b_lower + w× (b_upper - b_lower); Step 4: Calculate the turn-on ratio f_final = a_target × P_atm + b_target; Step 5: Safety constraint f_final = max(0.05, min(1.0, f_final)); Control algorithm example: Take the atmospheric pressure of 98.5 kPa and the target compaction rate of 3.2 kPa / s as an example: Determine adjacent compaction rates: Rlower = 3.0 kPa / s, Rupper = 3.5 kPa / s Calculate the interpolation weight: w = (3.2-3.0) / (3.5-3.0) = 0.4 Regression parameter interpolation: a3.2 = -0.0600 + 0.4×(-0.0760-(-0.0600)) = -0.0664 b3.2 = 6.360 + 0.4×(8.033-6.360) = 7.029 Calculate the final open ratio: ffinal = -0.0664×98.5 + 7.029 = 0.489 Safety check: 0.05 ≤ 0.489 ≤ 1.0 √ Specific implementation: only includes the cycle of extrusion and injection of consumables In a specific embodiment of the present invention, the pressure control device is used to perform a cyclic extrusion experiment on a layer containing only consumables to study the compaction behavior of the consumables under cyclic pressure and provide data support for optimizing the vacuum infusion process.

[0050] Experimental setup: Lamination configuration: A release sheet (120 mm × 300 mm), a flow mesh (100 mm × 300 mm), and a vacuum bag are placed in that order on a transparent tempered glass mold (900 mm × 800 mm × 5 mm). Butyl tape is used to seal the edges to ensure an airtight system.

[0051] Pressure Control Device: The pressure control device of this invention includes two independent hardware systems, one for controlling the pressure in the injection barrel and the other for the resin trap. The control box is equipped with a controller, vacuum proportional valve, vacuum solenoid valve, etc.

[0052] Cyclic extrusion parameters: Maximum compaction pressure is 97.6 kPa (absolute pressure is approximately 2.4 kPa, assuming atmospheric pressure is 100 kPa), minimum compaction pressure is 0 kPa (atmospheric pressure), and compaction rate range is 1 kPa / s to 5.5 kPa / s.

[0053] Data acquisition: An absolute pressure sensor (resolution 0.1 kPa) was used to record the injection and discharge pressures.

[0054] Experimental steps: 1. Lamination Stage: Clean the glass mold, apply the release cloth, guide mesh, and vacuum bag, and connect the feed and discharge pipes. Seal the system with sealing tape, set the discharge pressure to 0.5 kPa, and check for airtightness.

[0055] 2. Pre-extrusion stage: adjust the dispensing pressure to atmospheric pressure and maintain it for 1 minute.

[0056] 3. Cyclic compaction phase: 15 compaction cycles are performed, each cycle includes: Compaction stage: The discharge pressure is reduced from atmospheric pressure to 97.6 kPa compaction pressure at a specified rate (2 kPa / s or 4 kPa / s).

[0057] Compaction hold phase: maintain 97.6 kPa compaction pressure for 60 seconds.

[0058] Relaxation phase: Return the pressure to atmospheric pressure.

[0059] Relaxation hold phase: Maintain atmospheric pressure for 30 seconds.

[0060] 4. Post-processing stage: After completing 15 cycles, the glue outlet pressure was reduced to 0.5 kPa and degassing was carried out for 30 minutes.

[0061] 5. Glue injection: Pour silicone oil into the injection barrel and degas at 0.5 kPa for 5 minutes. Then, adjust the barrel pressure to 50 kPa and open the injection control valve to inject the glue. After the silicone oil has soaked the filament, close the injection control valve.

[0062] Experimental results: The experimental results show that the compaction rate and pressure control effects are good. In the two groups of experiments, the compaction rate of the 2 kPa / s group is 2.00 ± 0.02 kPa / s, The compaction rate of the 4 kPa / s group was 4.00 ± 0.04 kPa / s. During the pressure hold phase, the actual pressure was stabilized at the set pressure value with an accuracy of ±0.2 kPa.

[0063] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm, characterized by: It comprises two sets of independent hardware systems, a dual-pipeline control system and a pressure control box (201); the two sets of independent hardware systems comprise a material injection barrel system and a resin trap system, the material injection barrel system and the resin trap system are respectively controlled by the dual-pipeline control system, and the pressure control box (201) controls the two sets of independent hardware systems and the dual-pipeline control system.

2. The vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm according to claim 1, characterized in that: The injection barrel system comprises an injection barrel (219), a vacuum pump (217), and an absolute pressure sensor (220); the injection barrel (219) and the vacuum pump (217) are connected by a dual-pipeline control system, and the absolute pressure sensor (220) is installed on the injection barrel (219).

3. The vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm according to claim 2, characterized in that: The resin collector system includes a second stainless steel container (226), a second vacuum pump (211), and a second absolute pressure sensor (227); the second stainless steel container (226) and the second vacuum pump (211) are connected by a dual-pipeline control system, and the second absolute pressure sensor (227) is installed in the second stainless steel container (227).

4. The vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm according to claim 1, characterized in that: The dual-pipeline control system includes two independent vacuum lines: The first pipeline is equipped with a vacuum solenoid valve and a vacuum proportional valve to control the pressure range from atmospheric pressure to 79kPa below atmospheric pressure; The second line is equipped with a vacuum solenoid valve that works in conjunction with the first line to control the pressure range from 79 kPa below atmospheric pressure to 0.5 kPa absolute pressure.

5. A control method for a vacuum induction cycle extrusion pressure control device based on a double-layer linear algorithm according to any one of claims 1 to 4, characterized in that: Including pressure control method and compaction rate control method; The compaction rate control method is as follows: in the cyclic extrusion process, the compaction rate is precisely controlled by adjusting the opening ratio of the vacuum solenoid valve of the second pipeline of the control device, and a double-layer linear algorithm is used; The pressure control method adopts segmented pressure control, including high-pressure segment control and low-pressure segment control, which is controlled by the first pipeline of the control device or controlled by two pipelines together.

6. The vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm according to claim 5, characterized in that: The high voltage section control: When the pressure setting value is from atmospheric pressure to 79 kPa below atmospheric pressure, the pressure is controlled by the first pipeline of the control device, and the vacuum solenoid valve of the second pipeline is normally closed. The vacuum proportional valve is controlled by PID: proportional gain Kc=0.035, integral time Ti=0.07, derivative time Td=0; Control signal: y = (x / 80) × 5V, where x is the atmospheric pressure minus the target pressure, and y is the theoretical value of the input control signal; Vacuum solenoid valve switch control: always open when pressure deviation > 0.5kPa, otherwise open for 0.5 seconds per second.

7. The vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm according to claim 5, characterized in that: The low pressure section control: When the pressure setting value is 79 kPa below atmospheric pressure to 0.5 kPa absolute pressure, the pressure is controlled by two pipelines. Vacuum proportional valve set value control: input 5V when pressure <17kPa, otherwise 4.5V; Double solenoid valve coordinated control: the opening ratio is determined according to the direction and size of the pressure deviation; Dynamic correction algorithm: Optimize the opening ratio based on historical measurement values.

8. The vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm according to claim 7, characterized in that: In the dual solenoid valve coordinated control, the opening ratio of the vacuum solenoid valve is determined by the real-time measured pressure: When the measured value is greater than the set value, the solenoid valve of the first pipeline is normally closed, and the solenoid valve of the second pipeline is periodically opened. If the measured value is higher than the set value by a certain value, the solenoid valve of the second pipeline is normally open; otherwise, the opening ratio is y = max(0.05, min(1,(25-x) / 22)), where x is the pressure set value and y is the opening ratio. The solenoid valve opens once every two seconds according to this ratio. When the measured value is less than the set value, the solenoid valve of the second pipeline is normally closed, and the solenoid valve of the first pipeline is opened according to y = max(0.05,min(0.5, 0.05 + 0.0225(x-5))). The solenoid valve opens once every two seconds according to this ratio; When the measured value is equal to the set value, the solenoid valve of the first pipeline is closed and the solenoid valve of the second pipeline is opened at a ratio of 0.05; For the three solenoid valve opening ratios in these three cases, the ratios are corrected based on the past three pressure measurement values: when the measurement value is greater than the set value, if the opening ratio is too high, that is, the pressure measurement value is lower than the set value after adjustment, then the set value is reduced by 0.01 each time, with a minimum value of 0.05; when the measurement value is less than the set value, if the opening ratio is too high, that is, the pressure measurement value is higher than the set value after adjustment, then the set value is reduced by 0.01 each time, with a minimum value of 0.

05. 0.01, the minimum value is 0.

05. When the measured value is equal to the set value, if the opening ratio is too high, that is, the pressure measurement value is lower than the set value after adjustment, then reduce the set value and adjust it to open for 0.05 seconds every n seconds, and gradually increase n; if the opening ratio is too low, that is, the pressure measurement value is higher than the set value after adjustment, then increase the opening ratio, each time by 0.01, and the maximum value is 1.

9. The vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm according to claim 5, characterized in that: The two-layer linear algorithm includes First layer: Compaction rate regression line is established. For each standard compaction rate value, the atmospheric pressure-opening ratio regression equation is established: f_i = a_i × P_atm + b_i Among them, f_i is the opening ratio under the compaction rate R_i, P_atm is the current atmospheric pressure, a_i and b_i are regression coefficients; Second layer: target compaction rate interpolation algorithm.

10. The vacuum induction cycle extrusion pressure control method based on a double-layer linear algorithm according to claim 9, characterized in that: In the second layer, for any target compaction rate, the following steps are performed: Step 1: Determine the adjacent compaction rate and find the adjacent compaction rate value that satisfies Rlower ≤ Rtarget ≤ Rupper; Step 2: Calculate the interpolation weight w = (R_target - R_lower) / (R_upper - R_lower); Step 3: Regression parameter interpolation a_target = a_lower + w × (a_upper - a_lower)b_target = b_lower + w ×(b_upper - b_lower); Step 4: Calculate the turn-on ratio f_final = a_target × P_atm + b_target; Step 5: Safety constraint f_final = max(0.05, min(1.0, f_final)).

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