A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill and its method

Abstract

This invention discloses a dual closed-loop control system and method for rubber mixing pressure in a rubber mixing mill, relating to the field of automation control technology. The system sets a target pressure, monitors the feedback value of the external pressure closed loop, acquires the external pressure closed loop feedback value, calculates a first input value based on the target pressure and the external pressure closed loop feedback value, obtains a first output value based on the deviation between the first input value and a preset first input value threshold, uses the first output result as the input value of the internal pressure closed loop, collects the detected value of the pump inlet pressure, calculates a second input value based on the first output result and the detected pump inlet pressure, adjusts the control pressure of the pump inlet based on the deviation between the second input value and a preset second input value threshold, and controls the speed of the servo motor through a servo controller to stabilize the pump inlet side pressure.

Description

Technical Field

[0001] This invention relates to the field of automation control technology, specifically to a dual closed-loop control system and method for rubber mixing pressure in a rubber mixing mill. Background Technology

[0002] Rubber mixing mills are mainly used in the rubber and plastics industry for mixing various raw rubber materials and compounding agents, with closed-type rubber mixing mills being the most common type of mixing equipment. In the entire rubber mixing process, the top-bolt pressing and bottom-pressure mixing process is a crucial step, as the quality of the mixing directly affects the quality of the finished product.

[0003] During the internal mixing process, controlling the pressure accuracy of the top plug is crucial, directly affecting the quality of the extruded rubber. Existing methods for achieving constant pressure control generally employ a servo valve with single-pressure closed-loop control. However, this method suffers from significant pressure fluctuations during operation, making it difficult to meet the pressure control requirements for high-quality rubber mixing. Furthermore, servo valves are prone to malfunctions such as high oil temperature and valve core blockage, leading to slow control response and high equipment maintenance costs. Summary of the Invention

[0004] The purpose of this invention is to provide a solution to the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a dual closed-loop control method for rubber mixing pressure in a rubber mixing mill, the method comprising:

[0006] Step S1: Set the target pressure, monitor the feedback value of the external pressure closed loop, obtain the external pressure closed loop feedback value, and calculate the first input value based on the target pressure and the external pressure closed loop feedback value;

[0007] Step S2: Based on the deviation between the first input value and the preset first input value threshold, obtain the first output value, and perform amplitude limiting on the first output value to obtain the first output result;

[0008] Step S3: Use the first output result as the input value of the internal pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure;

[0009] Step S4: Based on the deviation between the second input value and the preset second input value threshold, obtain the second output value, and perform amplitude limiting on the second output value to obtain the second output result;

[0010] Step S5: Based on the second output result, adjust the control pressure at the pump inlet and control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

[0011] Furthermore, step S1 includes:

[0012] Step S1-1: Set the target pressure value P at the pump inlet. set ;

[0013] Step S1-2: The pressure feedback on the load side of the hydraulic pipeline is denoted as the external pressure closed-loop feedback. The values ​​of k external pressure closed-loop feedbacks are continuously collected to form an external pressure closed-loop feedback sequence, where T is the sampling time interval.

[0014] Step S1-3: Denote the i-th external pressure closed-loop feedback value in the external pressure closed-loop feedback sequence as P. loud,i Obtain the target pressure value P set Calculate the i-th first input value e 1,i The first input value e 1,i The calculation formula is e 1,i =P set -P loud,i ;

[0015] Step S1-4: Collect all the first input values ​​and save them in the form of a queue to obtain the sequence of first input values.

[0016] Furthermore, step S2 includes:

[0017] Step S2-1: Obtain the i-th, (i+1)-th, and (i+2)-th first input values ​​from the first input value sequence, and denot them as e. 1,i e1,i +1 and e 1,i+2 Obtain the upper limit threshold e of the first input value. 1Max and lower limit threshold e 1Min The preset first input value threshold includes e 1Max and e 1Min ;

[0018] Step S2-2: Obtain the upper limit threshold e of the first input value 1Max and lower limit threshold e 1Min , when e 1,i Condition e is met 1Min ≤e 1,i ≤e 1Max When the time comes, calculate the first output value out1, where the formula for out1 is out1 = P set +M, where M represents the pressure compensation value;

[0019] Step S2-3: When e 1,i Condition e is met 1,i <e 1Min , or e 1,i >e 1Max At that time, retrieve the historical result 'out' of the first output value from the previous loop.1,h And calculate the first output value out1. The formula for calculating out1 is out1 = out 1,h +K×(K p1 ×(e 1,i+2 -e 1,i+1 )+K i1 ×e 1,i+2 +K d1 ×(e 1,i+2 -2×e 1,i+1 +e 1,i ))+M, where K represents the pressure conversion factor, K p1 K i1 and K d1 These are the outer loop proportional coefficient, outer loop integral coefficient, and outer loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 1,h At that time, out 1,h =P set ;

[0020] Step S2-4: Set the first output value (out) as the upper limit. 1Max And the first output value output lower limit out 1Min When out1 > out 1Max At that time, the output value of out1 is out. 1Max When out1 < out 1Min At that time, the output value of out1 is out. 1Min When the condition is met, out 1Min ≤out1≤out 1Max When the output value of out1 is calculated in step S2-2 or step S2-3, the output value of out1 is recorded as the first output result out. 1,result .

[0021] The weighted algorithm in this application is an improvement on the PID algorithm, which is adapted to the implementation of dual closed-loop control of rubber mixing pressure of rubber mixing mill by PLC programming in actual production process;

[0022] The theoretical formula for the PID algorithm is:

[0023]

[0024] In the formula K p T is the proportionality coefficient. i Let T be the integration time constant. d Let e(t) be the differential time constant, e(t) be the error function, and u(t) be the output function.

[0025] As shown in the formula above, this is a continuous expression for PID control, but it cannot be implemented through PLC program code and requires discretization. If the sampling time interval of the PLC control is T, then at a certain moment:

[0026] Deviation e(k);

[0027] The integral is e(k) + e(k-1) + e(k-2) + ... + e(0);

[0028] The differential is (e(k) - e(k-1)) / T;

[0029] thereby The simplified formula is:

[0030]

[0031] Set the scaling factor K p Integral coefficient K i =K p ×T / T i Differential coefficient K d =K p ×T d / T; Substituting the set coefficients into the formula, the formula can be formed in the following form:

[0032]

[0033] Δu(k)=u(k)-u(k-1);

[0034]

[0035] Δu(k)=K p (e(k)-e(k-1))+K i e(k)+K d (e(k)-2×e(k-1)+e(k-2)),

[0036] The final output is: u(k) = u(k-1) + Δu(k);

[0037] By discretizing the PID algorithm formula, the final incremental PID formula is obtained.

[0038] The increment calculated by the formula is only related to the deviation values ​​of the three most recent times. The output is the control increment, which does not require accumulated error. The computational load is relatively small, so the real-time performance is relatively good. Since there is no need to accumulate error, integral runaway will not occur, avoiding system overshoot or oscillation.

[0039] Furthermore, step S3 includes:

[0040] Step S3-1: Obtain the first output result (out) 1,result ;

[0041] Step S3-2: The pressure feedback at the pump outlet is recorded as the internal pressure closed-loop feedback. The detection values ​​of r pump outlet pressure feedbacks are continuously collected to form the internal pressure closed-loop feedback sequence, where T is the sampling time interval.

[0042] Step S3-3: Record the detected value of the j-th pump inlet pressure in the internal pressure closed-loop feedback sequence as P. pump,j out 1,result Calculate the j-th second input value e 2,j The second input value e 2,j The calculation formula is e 2,j =out 1,result -P pump,j ;

[0043] Step S3-4: Collect all the second input values ​​and save them in the form of a queue to obtain the second input value sequence.

[0044] Furthermore, step S4 includes:

[0045] Step S4-1: Obtain the j-th, j+1-th, and j+2-th second input values ​​from the second input value sequence, respectively, and denote them as e. 2,j e 2,j+1 and e 2,j+2 Set the second input value threshold, including e 2Ma x and e 2Min ;

[0046] Step S4-2: Obtain the upper threshold e of the second input value 2Max and lower limit threshold e 2Min , when e 2,j Condition e is met 2Min ≤e 2,j ≤e 2Max When the time comes, calculate the second output value out2. The formula for calculating out2 is out2 = out 1,result ;

[0047] Step S4-3: When e 2,j Condition e is met 2,j <e 2Min , or e 2,j >e 2Max At that time, retrieve the historical result (out) of the second output value from the previous loop. 2,h And calculate the second output value out2. The formula for out2 is out2 = out 2,h +(K p2 ×(e 2,j+2 -e 2,j+1)+K i2 ×e 2,j+2 +K d2 ×(e 2,j+2 -2×e 2,j+1 +e 2,j ), where K p2 K i2 and K d2 These are the inner loop proportional coefficient, inner loop integral coefficient, and inner loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 2,h At that time, out 2,h =out 1,result ;

[0048] Step S4-4: Set the upper limit of the second output value (out) 2Max Second output value output lower limit out 2Min When out2 > out 2Max At that time, the output value of out2 is out 2Max When out2 < out 2Min At that time, the output value of out2 is out 2Min When the condition is met, out 2Min ≤out2≤out 2Max At this time, the output value of out2 is the calculation result of out2 in step S4-2 or step S4-3, and the output value of out2 is recorded as the second output result out. 2,result .

[0049] To better implement the above method, a dual closed-loop control system for rubber mixing pressure in a rubber mixing mill is also proposed.

[0050] The system includes: an outer loop input value management module, a first output value calculation module, an inner loop input value management module, a second output value calculation module, and an adjustment and control module;

[0051] The outer loop input value management module is used to manage the target pressure, monitor the feedback value of the outer pressure closed loop, obtain the feedback value of the outer pressure closed loop, and calculate the first input value based on the target pressure and the feedback value of the outer pressure closed loop.

[0052] The first output value calculation module is used to obtain a first output value based on the deviation between the first input value and a preset first input value threshold, and to perform amplitude limiting processing on the first output value to obtain a first output result.

[0053] The inner loop input value management module is used to take the first output result as the input value of the inner pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure.

[0054] The second output value calculation module is used to obtain a second output value based on the deviation between the second input value and a preset second input value threshold, and to perform amplitude limiting on the second output value to obtain a second output result.

[0055] The adjustment and control module is used to adjust the control pressure at the pump inlet according to the second output result, and to control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

[0056] Furthermore, the outer loop input value management module includes: a target pressure management unit, an outer loop feedback sampling unit, and a first input value management unit;

[0057] The target pressure management unit is used to manage the target pressure value at the pump inlet. The outer loop feedback sampling unit is used to continuously collect several values ​​of the external pressure closed loop feedback to form an external pressure closed loop feedback sequence. The first input value management unit is used to obtain the external pressure closed loop feedback value and the target pressure value, calculate the first input value, and collect the first input values ​​to obtain the first input value sequence.

[0058] Furthermore, the first output value calculation module includes: a first input limiting unit, a first input judgment unit, a pressure compensation unit, a first output value calculation unit, and a first output limiting unit;

[0059] The first input limiting unit is used to manage the first input value threshold. The first input judgment unit is used to compare the first input value with the first input value threshold and determine the calculation method of the first output value. The pressure compensation unit is used to perform pressure compensation on the first input value that meets the conditions. The first output value calculation unit is used to obtain the first output value through weighted calculation when the first input value meets the conditions. The first output limiting unit obtains the first output value, performs output limiting on the first output value, and calculates the first output result.

[0060] Furthermore, the inner loop input value management module includes: a first output result acquisition unit, an inner loop feedback sampling unit, and a second input value management unit;

[0061] The first output result acquisition unit is used to acquire the first output result. The inner loop feedback sampling unit is used to continuously collect the values ​​of several inner pressure closed loop feedbacks to form an outer pressure closed loop feedback sequence. The second input value management unit is used to acquire the inner pressure closed loop feedback value and the first output result, calculate the second input value, and collect the second input value to obtain the second input value sequence.

[0062] Furthermore, the second output value calculation module includes: a second input limiting unit, a second input judgment unit, a second output value assignment unit, a second output value calculation unit, and a second output limiting unit;

[0063] The second input limiting unit is used to manage the second input value threshold. The second input judgment unit is used to compare the second input value with the second input value threshold and determine the calculation method of the second output value. The second output value assignment unit is used to assign a value to the second input value that meets the conditions. The second output value calculation unit is used to obtain the second output value through weighted calculation when the second input value meets the conditions. The second output limiting unit obtains the first output value, performs output limiting on the first output value, and calculates the first output result.

[0064] Compared with the prior art, the beneficial effects of the present invention are:

[0065] 1. This invention adopts an automated servo control system. Compared with the traditional coordinated control of quantitative pumps and servo valves, the motor pump group does not need to be constantly running. The servo motor drives the pump to output pressure and flow as required, resulting in significant energy saving.

[0066] 2. Traditional servo valve control systems have low anti-interference capabilities, lag in pressure and flow regulation during the mixing process, and rely on valve regulation, resulting in low control accuracy and high valve failure rate. This invention uses a dual PID closed-loop control algorithm with high anti-interference capabilities, which can improve the stability of the pressure control system.

[0067] 3. This invention employs an automated feedback method, flexibly adjusting pressure control parameters through real-time pressure monitoring. In traditional rubber mixing methods, the internal mixing pressure parameters are fixed, making it difficult to adapt to the needs of different rubber compound formulations. This invention uses an adaptive pressure adjustment strategy, supporting different internal mixing pressures for different rubber compounds, offering high flexibility.

[0068] 4. This invention controls the pump's pressure and flow rate to achieve stable load pressure. Compared with traditional control systems, it reduces the use of valves in the hydraulic process and also reduces problems such as heat generation and wear of hydraulic valves during use. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the structure of a dual closed-loop control system for rubber mixing pressure in a rubber mixing mill according to the present invention.

[0070] Figure 2 This is a schematic flowchart of a dual closed-loop control method for rubber mixing pressure in a rubber mixing mill according to the present invention.

[0071] Figure 3 This is a schematic diagram of an embodiment of a dual closed-loop control method for rubber mixing pressure in a rubber mixing mill according to the present invention. Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Example: Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a technical solution: a dual closed-loop control system for rubber mixing pressure in a rubber mixing mill and its method.

[0074] The methods include:

[0075] Step S1: Set the target pressure, monitor the feedback value of the external pressure closed loop, obtain the external pressure closed loop feedback value, and calculate the first input value based on the target pressure and the external pressure closed loop feedback value;

[0076] Step S1 includes:

[0077] Step S1-1: Set the target pressure value P at the pump inlet. set ;

[0078] Step S1-2: The pressure feedback on the load side of the hydraulic pipeline is denoted as the external pressure closed-loop feedback. The values ​​of k external pressure closed-loop feedbacks are continuously collected to form an external pressure closed-loop feedback sequence, where T is the sampling time interval.

[0079] Step S1-3: Denote the i-th external pressure closed-loop feedback value in the external pressure closed-loop feedback sequence as P. loud,i Obtain the target pressure value P set Calculate the i-th first input value e 1,i The first input value e 1,i The calculation formula is e 1,i =P set -P loud,i ;

[0080] Step S1-4: Collect all the first input values ​​and save them in the form of a queue to obtain the sequence of first input values.

[0081] Step S2: Based on the deviation between the calculated first input value and the preset first input value threshold, obtain the first output value, and perform amplitude limiting on the first output value to obtain the first output result;

[0082] Step S2 includes:

[0083] Step S2-1: Obtain the i-th, (i+1)-th, and (i+2)-th first input values ​​from the first input value sequence, and denote them as e.1,i e1,i +1 and e 1,i+2 Obtain the upper limit threshold e of the first input value. 1Max and lower limit threshold e 1Min The preset first input value threshold includes e 1Max and e 1Min ;

[0084] Step S2-2: Obtain the upper limit threshold e of the first input value 1Max and lower limit threshold e 1Min , when e 1,i Condition e is met 1Min ≤e 1,i ≤e 1Max When the time comes, calculate the first output value out1, where the formula for out1 is out1 = P set +M, where M represents the pressure compensation value;

[0085] Step S2-3: When e 1,i Condition e is met 1,i <e 1Min , or e 1,i >e 1Max At that time, retrieve the historical result 'out' of the first output value from the previous loop. 1,h And calculate the first output value out1. The formula for calculating out1 is out1 = out 1,h +K×(K p1 ×(e 1,i+2 -e 1,i+1 )+K i1 ×e 1,i+2 +K d1 ×(e 1,i+2 -2×e 1,i+1 +e 1,i ))+M, where K represents the pressure conversion factor, K p1 K i1 and K d1 These are the outer loop proportional coefficient, outer loop integral coefficient, and outer loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 1,h At that time, out 1,h =P set ;

[0086] Step S2-4: Set the first output value (out) as the upper limit. 1Max And the first output value output lower limit out 1Min When out1 > out 1Max At that time, the output value of out1 is out. 1Max When out1 < out 1Min At that time, the output value of out1 is out.1Min When the condition is met, out 1Min ≤out1≤out 1Max When the output value of out1 is calculated in step S2-2 or step S2-3, the output value of out1 is recorded as the first output result out. 1,result .

[0087] Step S3: Use the first output result as the input value of the internal pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure;

[0088] Step S3 includes:

[0089] Step S3-1: Obtain the first output result (out) 1,result ;

[0090] Step S3-2: The pressure feedback at the pump outlet is recorded as the internal pressure closed-loop feedback. The detection values ​​of r pump outlet pressure feedbacks are continuously collected to form the internal pressure closed-loop feedback sequence, where T is the sampling time interval.

[0091] Step S3-3: Record the detected value of the j-th pump inlet pressure in the internal pressure closed-loop feedback sequence as P. pump,j out 1,result Calculate the j-th second input value e 2,j The second input value e 2,j The calculation formula is e 2,j =out 1,result -P pump,j ;

[0092] Step S3-4: Collect all the second input values ​​and save them in the form of a queue to obtain the second input value sequence.

[0093] Step S4: Based on the deviation between the calculated second input value and the preset second input value threshold, obtain the second output value, and perform amplitude limiting on the second output value to obtain the second output result;

[0094] Step S4 includes:

[0095] Step S4-1: Obtain the j-th, j+1-th, and j+2-th second input values ​​from the second input value sequence, respectively, and denote them as e. 2,j e 2,j+1 and e 2,j+2 Set the second input value threshold, including e 2Ma x and e 2Min ;

[0096] Step S4-2: Obtain the upper threshold e of the second input value 2Max and lower limit threshold e2Min , when e 2,j Condition e is met 2Min ≤e 2,j ≤e 2Max When the time comes, calculate the second output value out2. The formula for calculating out2 is out2 = out 1,result ;

[0097] Step S4-3: When e 2,j Condition e is met 2,j <e 2Min , or e 2,j >e 2Max At that time, retrieve the historical result (out) of the second output value from the previous loop. 2,h And calculate the second output value out2. The formula for out2 is out2 = out 2,h +(K p2 ×(e 2,j+2 -e 2,j+1 )+K i2 ×e 2,j+2 +K d2 ×(e 2,j+2 -2×e 2,j+1 +e 2,j ), where K p2 K i2 and K d2 These are the inner loop proportional coefficient, inner loop integral coefficient, and inner loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 2,h At that time, out 2,h =out 1,result ;

[0098] Step S4-4: Set the upper limit of the second output value (out) 2Max Second output value output lower limit out 2Min When out2 > out 2Max At that time, the output value of out2 is out 2Max When out2 < out 2Min At that time, the output value of out2 is out 2Min When the condition is met, out 2Min ≤out2≤out 2Max At this time, the output value of out2 is the calculation result of out2 in step S4-2 or step S4-3, and the output value of out2 is recorded as the second output result out. 2,result .

[0099] Step S5: Based on the second output result, adjust the control pressure at the pump inlet and control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

[0100] Step S5 includes: the final control pressure at the pump inlet is out. 2,result The servo motor speed is controlled by a servo controller to stabilize the pump inlet pressure at the outlet. 2,result The pressure is then delivered to the load side via hydraulic lines to form load pressure, thereby controlling the pressure stability of the entire system.

[0101] The following is a complete embodiment illustrating the operation of the present invention:

[0102] In such Figure 3 In the embodiment, the outer loop control closed loop is defined as: target pressure → calculation 1 → PID1 → calculation 2 → PID2 → pump outlet pressure → load pressure → load pressure detection feedback → calculation 1.

[0103] Calculation 2 → PID2 → Pump outlet pressure → Pump outlet pressure detection feedback → Calculation 2 is the inner loop control closed loop;

[0104] The outer loop control closed loop and the inner loop control closed loop constitute a dual closed-loop control system.

[0105] P pump This indicates the pump outlet pressure detected by the pump inlet pressure sensor;

[0106] P load : Load-side pressure detected by a pressure sensor on the load side;

[0107] Calculation 1 represents e1 = P set -P load Calculate 2 to represent e2 = out1 - P pump ;

[0108] P2 represents the load pressure generated when the hydraulic lines deliver the hydraulic pressure to the load side.

[0109] The disturbance process includes: the reverse force on the double-top bolt pressing block due to the rotation of the rotor in the confined space during the mixing process, and the pressure loss in the hydraulic pipeline.

[0110] Set P set =200, initial pressure at pump inlet 0, initial pressure detected on load side P load =0,K p1 =2,K i1 =0.4,K d1 =0, M=0, the calculation process in the example ignores the value of M, K p2 =1,K i2 =0.2,K d2 =0.03, the system enters its first sampling period starting from time t.

[0111] Within the first sampling period;

[0112] Outer loop closed-loop calculation:

[0113] e1(t-2)=P set -P load =0-0=0;

[0114] e1(t-1)=P set -P load =0-0=0;

[0115] e1(t)=P set -P load =200-0=200;

[0116] Δu(t)=K p1 ×(e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2×e1(t-1)+e1(t-2))+M;

[0117] Δu(t)=K p1 ×(200)+K i1 ×(200)+K d1 ×(200)+M;

[0118] Δu(t) = 480;

[0119] Converting PID calculation values ​​to pressure units:

[0120] out1=200+(480 / 1000×200)=296;

[0121] Inner ring calculation:

[0122] The pressure at the pump inlet is controlled by setting the pressure control motor to the servo driver via out2. Due to the high control precision of the servo controller, the actual detected pump inlet pressure value is approximately equal to the out1 value. In the calculation process of this embodiment, P... pump =out2=out1;

[0123] Therefore, e2 equals 0; within the error range of e2(t), the values ​​of e2(t), e2(t-1), and e2(t-2) are all 0 at time t;

[0124] out2 = out1 = 296;

[0125] P pump =296;

[0126] P load =296.

[0127] Similarly, in the second sampling period:

[0128] e1(t-2)=P set -P load =0-0=0;

[0129] e1(t-1)=P set -P load =200-0=200;

[0130] e1(t)=P set -P load =200-480=-96;

[0131] PID1 = K p1 ×(e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2×e1(t-1)+e1(t-2))+M;

[0132] PID1 = K p1 ×(-296)+K i1 ×(-96)+K d1 ×(-496)+M;

[0133] PID1 = -630.4;

[0134] Converting PID calculation values ​​to pressure units:

[0135] out1=296+(-630.4 / 1000×200)=169.92;

[0136] out2 = out1 = 169.92;

[0137] P pump =169.92;

[0138] P load =169.92.

[0139] Similarly, in the third sampling period:

[0140] e1(t-2)=Ps et -P load =200-0=200;

[0141] e1(t-1)=Ps et -P load =200-480=-96;

[0142] e1(t)=Ps et -P load =200-169.92=30.08;

[0143] PID1 = Kp1 ×(e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2×e1(t-1)+e1(t-2))+M;

[0144] PID1 = K p1 ×(126.08)+K i1 ×(30.08)+K d1 ×(422.08)+M

[0145] PID1 = 264.192;

[0146] out1=169.92+(264.192 / 1000×200)=222.7584;

[0147] out2 = out1 = 222.7584;

[0148] P pump =222.7584;

[0149] P load =222.7584.

[0150] Similarly, in the fourth sampling period:

[0151] e1(t-2)=P set -P load =200-480=-96;

[0152] e1(t-1)=P set -P load =200-169.92=30.08;

[0153] e1(t)=P set -P load =200-222.7584=-22.7584;

[0154] PID1 = K p1 ×(e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2×e1(t-1)+e1×(t-2))+M;

[0155] PID1 = K p1 ×(-52.8384)+K i1 ×(-22.7584)+K d1 ×(-178.9184)+M;

[0156] PID1 = -114.7802;

[0157] out1=222.7584+(-114.7802 / 1000×200)=199.8024;

[0158] out2 = out1 = 199.8024;

[0159] P pump =199.8024;

[0160] P load =199.8024.

[0161] Similarly, in the fifth sampling period:

[0162] e1(t-2)=P set -P load =200-169.92=30.08;

[0163] e1(t-1)=P set -P load =200-222.7584=-22.7584;

[0164] e1(t)=P set -P load =200-199.8024=0.1976;

[0165] PID1 = K p1 (e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2×e1(t-1)+e1×(t-2))+M;

[0166] PID1 = K p1 ×(22.956)+K i1 ×(0.1976)+K d1 (75.7944)+M;

[0167] PID1 = 45.995;

[0168] out1=199.8024+(45.995 / 1000×200)=209.0014;

[0169] out2 = out1 = 209.0014;

[0170] P pump =209.0014;

[0171] P load＝ 209.0014.

[0172] Similarly, in the sixth sampling period:

[0173] e1(t-2)=P set -P load =200-222.7584=-22.7584;

[0174] e1(t-1)=P set -P load =200-199.8024=0.1976;

[0175] e1(t)=P set -P load =200 - 209.0014 = -9.0014;

[0176] PID1 = K p1 ×(e1(t)-e1(t-1))+K i1 ×e1(t)+K d1 ×(e1(t)-2e1(t-1)+e1(t-2))+M;

[0177] PID1 = Kp1 × (-9.199) + K i1 ×(-9.0014)+K d1 ×(-32.155)+M;

[0178] PID1 = -21.9985;

[0179] out1=209.0014+(-21.9985 / 1000×200)=204.6017;

[0180] out2 = out1 = 204.6017;

[0181] P pump =204.6017;

[0182] P load =204.6017.

[0183] Through the above embodiments, P load After oscillating in the first two cycles, the pressure reached its peak at the fifth sampling point P. load The pressure can then be achieved within ±5% of the set pressure deviation. Throughout the process, the PID controller continuously adjusts the settings, and the deviation value (e) decreases until the set pressure is reached.

[0184] The system includes:

[0185] The system comprises an outer loop input value management module, a first output value calculation module, an inner loop input value management module, a second output value calculation module, and an adjustment and control module.

[0186] The outer loop input value management module includes: a target pressure management unit, an outer loop feedback sampling unit, and a first input value management unit;

[0187] The target pressure management unit is used to manage the target pressure value at the pump inlet. The outer loop feedback sampling unit is used to continuously collect several values ​​of the external pressure closed loop feedback to form an external pressure closed loop feedback sequence. The first input value management unit is used to obtain the external pressure closed loop feedback value and the target pressure value, calculate the first input value, and collect the first input values ​​to obtain the first input value sequence.

[0188] The outer loop input value management module is used to manage the target pressure, monitor the feedback value of the outer pressure closed loop, obtain the feedback value of the outer pressure closed loop, and calculate the first input value based on the target pressure and the feedback value of the outer pressure closed loop.

[0189] The first output value calculation module includes: a first input limiting unit, a first input judgment unit, a pressure compensation unit, a first output value calculation unit, and a first output limiting unit;

[0190] The first input limiting unit is used to manage the first input value threshold. The first input judgment unit is used to compare the first input value with the first input value threshold and determine the calculation method of the first output value. The pressure compensation unit is used to perform pressure compensation on the first input value that meets the conditions. The first output value calculation unit is used to obtain the first output value through weighted calculation when the first input value meets the conditions. The first output limiting unit obtains the first output value, performs output limiting on the first output value, and calculates the first output result.

[0191] The first output value calculation module is used to obtain the first output value based on the deviation between the first input value and the preset first input value threshold, and to perform amplitude limiting processing on the first output value to obtain the first output result.

[0192] The inner loop input value management module is used to take the first output result as the input value of the inner pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure.

[0193] The inner loop input value management module includes: a first output result acquisition unit, an inner loop feedback sampling unit, and a second input value management unit.

[0194] The first output result acquisition unit is used to acquire the first output result. The inner loop feedback sampling unit is used to continuously collect the values ​​of several inner pressure closed loop feedbacks to form an outer pressure closed loop feedback sequence. The second input value management unit is used to acquire the inner pressure closed loop feedback value and the first output result, calculate the second input value, and collect the second input value to obtain the second input value sequence.

[0195] The second output value calculation module is used to obtain the second output value based on the deviation between the calculated second input value and the preset second input value threshold, and to perform amplitude limiting processing on the second output value to obtain the second output result.

[0196] The second output value calculation module includes: a second input limiting unit, a second input judgment unit, a second output value assignment unit, a second output value calculation unit, and a second output limiting unit. The second input limiting unit manages the second input value threshold. The second input judgment unit compares the second input value with the second input value threshold to determine the calculation method of the second output value. The second output value assignment unit assigns values ​​to second input values ​​that meet the conditions. The second output value calculation unit calculates the second output value by weighted calculation when the second input value meets the conditions. The second output limiting unit obtains the first output value, limits the output of the first output value, and calculates the first output result.

[0197] The adjustment and control module is used to adjust the control pressure at the pump inlet based on the second output result, and to control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

[0198] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for dual closed-loop control of rubber mixing pressure in a rubber mixing mill, characterized in that: The methods include: Step S1: Set the target pressure, monitor the feedback value of the external pressure closed loop, obtain the external pressure closed loop feedback value, and calculate the first input value based on the target pressure and the external pressure closed loop feedback value; Step S2: Based on the deviation between the first input value and the preset first input value threshold, obtain the first output value, and perform amplitude limiting on the first output value to obtain the first output result; Step S3: Use the first output result as the input value of the internal pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure; Step S4: Based on the deviation between the second input value and the preset second input value threshold, obtain the second output value, and perform amplitude limiting on the second output value to obtain the second output result; Step S5: Based on the second output result, adjust the control pressure at the pump inlet and control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

2. The method for dual closed-loop control of rubber mixing pressure in a rubber mixing mill according to claim 1, characterized in that: Step S1 includes: Step S1-1: Set the target pressure value P at the pump inlet. set ; Step S1-2: The pressure feedback on the load side of the hydraulic pipeline is denoted as the external pressure closed-loop feedback. The values ​​of k external pressure closed-loop feedbacks are continuously collected to form an external pressure closed-loop feedback sequence, where T is the sampling time interval. Step S1-3: Denote the i-th external pressure closed-loop feedback value in the external pressure closed-loop feedback sequence as P. loud,i Obtain the target pressure value P set Calculate the i-th first input value e 1,i The first input value e 1,i The calculation formula is e 1,i =P set -P loud,i ; Step S1-4: Collect all the first input values ​​and save them in the form of a queue to obtain the sequence of first input values.

3. The method for dual closed-loop control of rubber mixing pressure in a rubber mixing mill according to claim 2, characterized in that: Step S2 includes: Step S2-1: Obtain the i-th, (i+1)-th, and (i+2)-th first input values ​​from the first input value sequence, and denot them as e. 1,i , e1,i+1 and e 1,i+2 Obtain the upper limit threshold e of the first input value. 1Max and lower limit threshold e 1Min The preset first input value threshold includes e 1Max and e 1Min ; Step S2-2: Obtain the upper limit threshold e of the first input value 1Max and lower limit threshold e 1Min , when e 1,i Condition e is met 1Min ≤e 1,i ≤e 1Max When the time comes, calculate the first output value out1, where the formula for out1 is out1 = P set +M, where M represents the pressure compensation value; Step S2-3: When e 1,i Condition e is met 1,i <e 1Min , or e 1,i >e 1Max At that time, retrieve the historical result 'out' of the first output value from the previous loop. 1,h And calculate the first output value out1. The formula for calculating out1 is out1 = out 1,h +K×(K p1 ×(e 1,i+2 -e 1,i+1 )+K i1 ×e 1,i+2 +K d1 ×(e 1,i+2 -2×e 1,i+1 +e 1,i ))+M, where K represents the pressure conversion coefficient, K p1 K i1 and K d1 These are the outer loop proportional coefficient, outer loop integral coefficient, and outer loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 1,h At that time, out 1,h =P set ; Step S2-4: Set the first output value (out) as the upper limit. 1Max And the first output value output lower limit out 1Min When out1 > out 1Max At that time, the output value of out1 is out 1Max When out1 < out 1Min At that time, the output value of out1 is out 1Min When the condition is met, out 1Min ≤out1≤out 1Max When the output value of out1 is calculated in step S2-2 or step S2-3, the output value of out1 is recorded as the first output result out. 1,result .

4. The method for dual closed-loop control of rubber mixing pressure in a rubber mixing mill according to claim 3, characterized in that: Step S3 includes: Step S3-1: Obtain the first output result (out) 1,result ; Step S3-2: The pressure feedback at the pump outlet is recorded as the internal pressure closed-loop feedback. The detection values ​​of r pump outlet pressure feedbacks are continuously collected to form the internal pressure closed-loop feedback sequence, where T is the sampling time interval. Step S3-3: Record the detected value of the j-th pump inlet pressure in the internal pressure closed-loop feedback sequence as P. pump,j out 1,result Calculate the j-th second input value e 2,j The second input value e 2,j The calculation formula is e 2,j =out 1,result -P pump,j ; Step S3-4: Collect all the second input values ​​and save them in the form of a queue to obtain the second input value sequence.

5. The method for dual closed-loop control of rubber mixing pressure in a rubber mixing mill according to claim 4, characterized in that: Step S4 includes: Step S4-1: Obtain the j-th, j+1-th, and j+2-th second input values ​​from the second input value sequence, respectively, and denote them as e. 2,j e 2,j+1 and e 2,j+2 Set the second input value threshold, including e 2Ma x and e 2Min ; Step S4-2: Obtain the upper threshold e of the second input value 2Max and lower limit threshold e 2Min , when e 2,j Condition e is met 2Min ≤e 2,j ≤e 2Max When the time comes, calculate the second output value out2. The formula for calculating out2 is out2 = out 1,result ; Step S4-3: When e 2,j Condition e is met 2,j <e 2Min , or e 2,j >e 2Max At that time, retrieve the historical result 'out' of the second output value from the previous loop. 2,h And calculate the second output value out2. The formula for out2 is out2 = out 2,h +(K p2 ×(e 2,j+2 -e 2,j+1 )+K i2 ×e 2,j+2 +K d2 ×(e 2,j+2 -2×e 2,j+1 +e 2,j ), where K p2 K i2 and K d2 These are the inner loop proportional coefficient, inner loop integral coefficient, and inner loop differential coefficient, respectively. When the `out` parameter from the previous loop cannot be obtained... 2,h At that time, out 2,h =out 1,result ; Step S4-4: Set the upper limit of the second output value (out) 2Max Second output value output lower limit out 2Min When out2 > out 2Max At that time, the output value of out2 is out 2Max When out2 < out 2Min At that time, the output value of out2 is out 2Min When the condition is met, out 2Min ≤out2≤out 2Max At this time, the output value of out2 is the calculation result of out2 in step S4-2 or step S4-3, and the output value of out2 is recorded as the second output result out. 2,result .

6. A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill, used to execute the dual closed-loop control method for rubber mixing pressure in a rubber mixing mill as described in any one of claims 1-5, characterized in that: The system includes: The system comprises an outer loop input value management module, a first output value calculation module, an inner loop input value management module, a second output value calculation module, and an adjustment and control module. The outer loop input value management module is used to manage the target pressure, monitor the feedback value of the outer pressure closed loop, obtain the outer pressure closed loop feedback value, and calculate the first input value based on the target pressure and the outer pressure closed loop feedback value; The first output value calculation module is used to obtain a first output value based on the deviation between the first input value and a preset first input value threshold, and to perform amplitude limiting processing on the first output value to obtain a first output result. The inner loop input value management module is used to take the first output result as the input value of the inner pressure closed loop, collect the detection value of the pump outlet pressure, and calculate the second input value based on the first output result and the detection value of the pump outlet pressure. The second output value calculation module is used to obtain a second output value based on the deviation between the second input value and a preset second input value threshold, and to perform amplitude limiting on the second output value to obtain a second output result. The adjustment and control module is used to adjust the control pressure at the pump inlet according to the second output result, and to control the speed of the servo motor through the servo controller to stabilize the pressure at the pump inlet.

7. A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill according to claim 6, characterized in that: The outer loop input value management module includes: a target pressure management unit, an outer loop feedback sampling unit, and a first input value management unit; The target pressure management unit is used to manage the target pressure value at the pump inlet. The outer loop feedback sampling unit is used to continuously collect several values ​​of the external pressure closed loop feedback to form an external pressure closed loop feedback sequence. The first input value management unit is used to obtain the external pressure closed loop feedback value and the target pressure value, calculate the first input value, and collect the first input values ​​to obtain the first input value sequence.

8. A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill according to claim 6, characterized in that: The first output value calculation module includes: a first input limiting unit, a first input judgment unit, a pressure compensation unit, a first output value calculation unit, and a first output limiting unit; The first input limiting unit is used to manage the first input value threshold. The first input judgment unit is used to compare the first input value with the first input value threshold and determine the calculation method of the first output value. The pressure compensation unit is used to perform pressure compensation on the first input value that meets the conditions. The first output value calculation unit is used to obtain the first output value through weighted calculation when the first input value meets the conditions. The first output limiting unit obtains the first output value, performs output limiting on the first output value, and calculates the first output result.

9. A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill according to claim 6, characterized in that: The inner loop input value management module includes: a first output result acquisition unit, an inner loop feedback sampling unit, and a second input value management unit; The first output result acquisition unit is used to acquire the first output result. The inner loop feedback sampling unit is used to continuously collect the values ​​of several inner pressure closed loop feedbacks to form an outer pressure closed loop feedback sequence. The second input value management unit is used to acquire the inner pressure closed loop feedback value and the first output result, calculate the second input value, and collect the second input value to obtain the second input value sequence.

10. A dual closed-loop control system for rubber mixing pressure in a rubber mixing mill according to claim 6, characterized in that: The second output value calculation module includes: a second input limiting unit, a second input judgment unit, a second output value assignment unit, a second output value calculation unit, and a second output limiting unit; The second input limiting unit is used to manage the second input value threshold. The second input judgment unit is used to compare the second input value with the second input value threshold and determine the calculation method of the second output value. The second output value assignment unit is used to assign a value to the second input value that meets the conditions. The second output value calculation unit is used to obtain the second output value through weighted calculation when the second input value meets the conditions. The second output limiting unit obtains the first output value, performs output limiting on the first output value, and calculates the first output result.

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