Fixed-value batching method and system for powder material

Abstract

The invention relates to the technical field of powder batching monitoring, and discloses a fixed-value batching method and system for a powder material, and the method comprises the steps: carrying out the dynamic correction of a spiral servo and a stirring motor through a cascade PID control and time prediction feedforward control method; on-line self-adaptive adjustment of key batching parameters in the fixed-value batching process of the powder material can be achieved, the fixed-value batching precision is improved, the productivity is improved, the pollution risk caused by manual supplement and the like due to out-of-tolerance in the production process is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder batching monitoring, and particularly relates to a method and system for fixed-value batching of powder materials. Background Art

[0002] In the application process of powder raw materials, such as cathode materials for batteries, it is usually necessary to weigh, convey, mix, etc. powder materials through batching equipment. Due to the characteristics of powder materials such as easy caking, easy water absorption, and large differences in fluidity, existing powder material batching equipment has problems that the batching error exceeds the allowable error range of batching due to the frequent switching of powder materials and the influence of on-site environment and other factors, and manual supplementary feeding or other additional measures are required. Moreover, this manual supplementary feeding method prolongs the batching time, greatly reduces the batching production capacity, and at the same time, manual supplementary feeding also increases the risk of foreign matter introduction. It can be seen that there is a problem in the prior art that it is difficult to achieve continuous and high-precision fixed-value batching of powder materials. Summary of the Invention

[0003] The present invention provides a method and system for fixed-value batching of powder materials, which are used to solve the problem in the prior art that it is difficult to achieve continuous and high-precision fixed-value batching of powder materials.

[0004] To solve the above technical problems, the technical solutions proposed by the present invention are as follows:

[0005] In a first aspect, the present application provides a method for fixed-value batching of powder materials, including:

[0006] S1: When the weight of the powder material in the silo is greater than the target weight, start the fixed-value batching program;

[0007] S2: Determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight before batching, otherwise give an alarm prompt;

[0008] S3: Adjust the batching device, start timing for fixed-value batching, control the batching device to enter the feeding stage at the first speed, and execute the first control strategy; when the batching weight is greater than or equal to the first target weight, enter the feeding stage at the second speed, and execute the second control strategy; when the batching weight is greater than or equal to the second target weight, enter the feeding stage at the third speed, and execute the third control strategy; predict the fixed-value batching time t during the feeding stage at the third speed, and perform a jog feeding process according to the predicted fixed-value batching time t; the first speed is greater than the second speed, and the second speed is greater than the third speed;

[0009] S4: After the jog feeding process ends, determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight after batching; otherwise, give an alarm prompt.

[0010] S5: Take the absolute value of the weight before batching minus the absolute value of the weight after batching as the batching error. If the absolute value of the batching error is less than or equal to the allowable batching error, it is determined that the batching is normal; otherwise, it is determined that the batching is out of tolerance.

[0011] In a second aspect, the present application also provides a fixed-value batching system for powder materials, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the method described in the first aspect above are implemented.

[0012] The present invention has the following beneficial effects:

[0013] The fixed-value batching method for powder materials provided by the present application can perform dynamic correction on the screw servo and the stirring motor through the methods of cascade PID control and time prediction feedforward control, and can realize the online adaptive adjustment of key batching parameters such as fast feeding speed, medium feeding speed, slow feeding speed, and lead amount during the fixed-value batching process of powder materials. It not only improves the fixed-value batching accuracy, but also improves the production capacity, reduces the pollution risk brought by manual supplementation due to out-of-tolerance during the production process, and improves the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0015] Figure 1 It is the second flowchart of a fixed-value batching method for powder materials provided by the present application;

[0016] Figure 2 It is the second flowchart of a fixed-value batching method for powder materials provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To facilitate the understanding of the present invention, the following will describe the present invention in a more comprehensive and detailed manner in conjunction with the accompanying drawings of the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0018] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0019] Unless otherwise specified, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0020] It should be understood that powder materials have characteristics such as easy caking, easy water absorption, and large differences in fluidity. In the prior art, there is a problem that it is difficult to achieve continuous and high-precision fixed-value batching of powder materials. Based on this, the present application provides a fixed-value batching method for powder materials, and this method can be applied to a fixed-value batching device for powder materials. In one example, the fixed-value batching device includes, but is not limited to: a weighing instrument for weighing the weights of the bin, stirring motor, screw servo, cut-off valve, upper flexible connection, lower flexible connection, powder material, and components directly connected to the device, etc.; a stirring motor for stirring the powder material in the bin, which is frequency conversion controlled; a screw servo for conveying the powder material, which is a servo-driven screw; a cut-off valve for cutting off the conveying of the powder material; a bin, which is a storage tank for receiving, storing, and conveying the powder material; an upper flexible connection for connecting the downstream pipe of the upstream equipment; and a lower flexible connection for connecting the downstream pipe of the downstream equipment.

[0021] It is further worth pointing out that the batching weight in the present application refers to the indicated weight of the weighing instrument at present. The medium feeding amount refers to the remaining weight from the target weight during the rapid feeding process. The slow feeding amount refers to the remaining weight from the target weight during the medium-speed feeding process. The fine feeding amount refers to the remaining weight from the target weight during the slow process. The jog feeding is in the JOG mode, that is, jogging at a low speed for safe operation. The jog cycle is the sum of the jog time and the interval time, and both can be set; the lead amount refers to the remaining weight from the target weight. The intermittent operation cycle is the sum of the operation time and the stop time, and both can be set; the batching weight is the absolute value of the indicated weight of the weighing instrument at present.

[0022] Please refer to Figure 1 A fixed-value batching method for powder materials provided by the present application includes:

[0023] S1: When the weight of the powder material in the bin is greater than the target weight, start the fixed-value batching program.

[0024] In this step, the weight of the powder material in the bin can be determined by the weighing instrument.

[0025] S2: Judge whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the current weight of the weighing instrument as the weight before batching, otherwise give an alarm prompt.

[0026] In this step, the way of giving an alarm can be voice alarm, bell alarm, etc. This is only an example here and is not limited.

[0027] S3: Adjust the batching device, start timing for fixed-value batching, control the batching device to enter the feeding stage at the first speed, and execute the first control strategy; when the batching weight is greater than or equal to the first target weight, enter the feeding stage at the second speed, and execute the second control strategy; when the batching weight is greater than or equal to the second target weight, enter the feeding stage at the third speed, and execute the third control strategy; predict the fixed-value batching time t during the feeding stage at the third speed, and perform jog feeding according to the predicted fixed-value batching time t; the first speed is greater than the second speed, and the second speed is greater than the third speed.

[0028] In this step, adjusting the batching device includes starting the weighing instrument to return to zero (i.e., taring the current weight), opening the cut-off valve, starting the spiral servo to feed at the first speed, controlling the spiral to convey the powder material in the silo through the cut-off valve, and controlling the stirring motor to run intermittently at a set speed.

[0029] Specifically, the feeding stage at the first speed refers to the fast feeding stage, the feeding stage at the second speed refers to the medium-speed feeding stage, and the feeding stage at the third speed refers to the slow feeding stage.

[0030] S4: After the jog feeding process ends, determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight after batching, otherwise give an alarm prompt.

[0031] In this step, the alarm method can be voice alarm, bell alarm, etc. This is only an example here and is not limited.

[0032] S5: Take the absolute value of the weight before batching minus the absolute value of the weight after batching as the batching error. If the absolute value of the batching error is less than or equal to the allowable batching error, it is determined that the batching is normal, otherwise it is determined that the batching is out of tolerance.

[0033] In this step, the allowable batching error can be determined according to process and quality standard specifications.

[0034] The above fixed-value batching method for powder materials can dynamically correct the spiral servo and the stirring motor through the cascade PID control and time prediction feedforward control methods, and can realize the online adaptive adjustment of key batching parameters such as fast feeding speed, medium-speed feeding speed, slow feeding speed, and lead during the fixed-value batching process of powder materials. It not only improves the fixed-value batching accuracy, but also improves the production capacity, reduces the pollution risk brought by manual supplementation due to out-of-tolerance during the production process, and improves the production efficiency.

[0035] It is worth noting that in this application, the cascade PID control model is adopted in the fast feeding stage, medium-speed feeding stage, and slow feeding stage as follows:

[0036] S11: Calculate the helical servo speed V s The PWM of the duty cycle, where PWM = batching speed / maximum rotational speed of the servo motor operation;

[0037] S12: For the outer-loop PID control, use the actual batching weight m p as the actual measured value, the value obtained by subtracting the fine feeding amount from the target weight as the set value, use the proportional coefficient term P as the control parameter. When adjusting the control parameter, first adjust the inner loop, then the outer loop, adjust the outer loop to the required P, and obtain the output control quantity V under the adjustment of the control parameter P n ;

[0038] S13: For the inner-loop PID control, use the output control quantity V n as the set value, the current helical servo speed V s duty cycle PWM as the actual measured value, use the proportional coefficient term P as the control parameter. When adjusting the control parameter, first disconnect the outer loop, adjust to the required P, and obtain the output control quantity V under the adjustment of the control parameter P u ＇ , and set the upper limit value V p of the helical servo speed; In this way, it is convenient to restrict the maximum speed according to the needs of the product, which is a speed limit protection on top of the PID algorithm.

[0039] S14: Convert the output V u ＇ duty cycle obtained by the inner loop into the helical servo speed V u , where V u = V u ＇ * batching speed range max ;

[0040] S15: Set the helical servo speed V u as the new helical servo speed, and return to S11 for iteration until entering the next feeding stage.

[0041] Next, as Figure 2 shown below, a complete example is used to describe the steps of the above-mentioned fixed-value batching method for powder materials in detail as follows:

[0042] Step 1: When the weight of the powder material in the silo is greater than the target weight, start fixed-value batching;

[0043] Step 2: Judge whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight before batching, otherwise give an alarm prompt;

[0044] Step 3: Start the weighing instrument to return to zero (i.e., tare the current weight); open the cutting valve; the screw servo starts rapid feeding, and the screw conveys the powder material in the silo through the cutting valve; the stirring motor runs intermittently at a set speed; start the fixed-value batching timing;

[0045] Step 4: In the rapid feeding stage, adopt the cascade PID control method to adaptively adjust the screw servo speed. The initial value of the screw servo speed is set to V s , and the batching weight range of the cascade PID control is m d = m t – m t3 , the current batching speed V p = m d / t b , where t b represents the step size. Among them, m t is the target weight, m t3 is the weight of the fine feeding amount. The rapid feeding stage has little impact on batching over-tolerance but has a greater impact on batching time. Therefore, it is not necessary to control frequently and the value of t b can be set larger. The control strategy is as follows:

[0046] 1. Calculate the PWM of the duty cycle of the screw servo speed V s , PWM = batching speed / maximum batching speed;

[0047] 2. Outer loop PID control. In the Siemens PLC environment, take the actual batching weight m p as the actual measured value, and the value obtained by subtracting the fine feeding amount from the target weight as the set value. Only the proportional coefficient term P of the control parameters is used. When adjusting the parameters, first adjust the inner loop, and then adjust the outer loop. Adjust the outer loop to the appropriate P to ensure the rapid adjustment of the screw servo speed. Under the adjustment of P, the output control quantity V n is obtained;

[0048] 3. Inner loop PID control. In the Siemens PLC environment, take the V n obtained in step 2 as the set value, and the duty cycle PWM of the current screw servo speed V s as the actual measured value. Only the proportional coefficient term P of the control parameters is used. Under the adjustment of P, the output control quantity V u ＇ is obtained. When adjusting the parameters, first disconnect the outer loop, adjust to the appropriate P to ensure the rapid adjustment of the screw servo speed. At the same time, to ensure that the batching speed does not increase too much, an upper limit value can be set for the maximum value V p of the screw servo speed;

[0049] 4. Convert the duty cycle of the output V u ＇ obtained from the inner loop into the screw servo speed V u , Vu = V u ＇ * Batching speed range max ;

[0050] 5. Set V u as the new screw servo speed and return to step 1.

[0051] Because the actual batching speed V p is mainly adjusted by the screw servo speed, the stirring speed has a relatively small impact on the actual batching speed V p . The stirring speed refers to the change of the screw servo and is adjusted in a certain proportion synchronously.

[0052] Step 5. When the batching weight is greater than or equal to the target weight minus the medium feeding amount, enter the medium-speed feeding stage, turn off the stirring motor. In the medium-speed feeding stage, continue to use the cascade PID model of the fast feeding stage, and the value of t b is taken to be slightly smaller than that of the fast feeding.

[0053] Step 6. When the batching weight is greater than or equal to the target weight minus the slow feeding amount, enter the slow feeding process, continue to use the cascade PID model of the fast feeding stage, and the value of t b is taken to be slightly smaller than that of the medium-speed feeding.

[0054] It should be noted that the period t from the start of fixed-value batching timing to the end of slow feeding determines the optimal range value of fixed-value batching that ensures both batching accuracy and batching time. Below this range may lead to batching errors, and exceeding this range will reduce production capacity. Therefore, a feedforward control method using time prediction is adopted on the basis of cascade PID control.

[0055] Step 7. In the slow feeding stage, predict the fixed-value batching time, and predict the fixed-value batching time t = t0 + t p + t j ;

[0056] t0 is the current fixed-value batching timing time, t p is the predicted time for the uncompleted fixed-value batching in the third-speed feeding stage, and t j is the predicted time for the jog feeding process;

[0057] t p satisfies the following relational expression:

[0058] t p = (m t - m t0 - m t3 ) / V u ;

[0059] Among them, m tis the target weight, V u is the predicted batching speed, m t0 is the current actual batching weight, m t3 is the weight of the fine feeding amount.

[0060] Let the single jogging time be t1 and the single interval time be t2, then t j =(m t3 / V j )*(t1 / (t1 + t2)).

[0061] Among them, V j is the batching speed during the jogging process, taking the batching speed at the previous fixed - value batching jogging. Let m tj1 , m tj0 be the weights at the moments before and after the single jogging respectively, then V j =(m tj1 -m tj0 ) / t1. In the formula, m tj1 , m tj0 are the weights at the moments before and after the single jogging respectively, and t1 is the single jogging time.

[0062] If the predicted fixed - value batching time t is lower than the optimal range value, it indicates that the material fluidity is too good and it is easy to exceed the tolerance. Then when the fixed - value batching time t is equal to the minimum value of the optimal range, the slow feeding is closed and the screw servo is started to enter the jogging feeding. The optimal range is the empirical value obtained from historical data.

[0063] If the predicted fixed - value batching time t exceeds the optimal range value, it indicates that the material fluidity is poor. Then when the batching weight is greater than or equal to the target weight minus the fine feeding amount, the jogging feeding stage is entered after a delay. The delay amount can be a time delay or a reduction in the fine feeding amount, and the delay amount is set according to the difference between the predicted fixed - value batching time t and the optimal range value.

[0064] If the predicted fixed - value batching time t is within the optimal range value, then it is judged whether the batching weight is greater than or equal to the target weight minus the fine feeding amount. When the batching weight is greater than or equal to the target weight minus the fine feeding amount, the slow feeding is closed and the screw servo is started to enter the jogging feeding step;

[0065] Step 8, during the jogging feeding process, judge whether the batching weight is greater than or equal to the target weight minus the lead amount, and then judge whether the batching weight increases within n jogging cycles;

[0066] Step 9, when the batching weight is greater than or equal to the target weight minus the lead amount and the batching weight increases within n jogging cycles, then continue to judge whether the batching weight is greater than or equal to the target weight;

[0067] Step 10: When the batching weight is greater than or equal to the target weight, or when the batching weight is greater than or equal to the target weight minus the lead, and the batching weight does not increase within n jogging cycles, the fixed-value batching is completed, and the screw servo and jogging feeding are turned off.

[0068] Step 11: Determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight after batching; otherwise, give an alarm prompt.

[0069] Step 12: The absolute value of the weight before batching minus the absolute value of the weight after batching is used as the batching error. Determine whether the absolute value of the batching error is less than or equal to the allowable batching error. The allowable batching error is generally determined according to process and quality standard specifications. When the absolute value of the batching error is less than or equal to the allowable batching error, it is determined that the batching is normal; otherwise, it is determined that the batching is out of tolerance.

[0070] Further, taking the high-precision fixed-value batching of cobalt tetroxide powder material as an example, the steps of the fixed-value batching method for powder materials provided by this application are described as follows. This is only an example here and is not limited. As a transformable implementation manner, other types of powder materials can also be used to describe the steps of the fixed-value batching method provided by this application.

[0071] It should be noted that cobalt tetroxide has the characteristics of easy caking, easy water absorption, and large fluidity difference. When cutting products, the first tank or even the first few tanks of materials need to be manually adjusted for batching parameters multiple times to meet the batching accuracy requirements for production. After adopting dynamic correction, there is no need for manual parameter adjustment, and the batching accuracy requirements can be met in the first tank of materials. Subsequently, continuous dynamic optimization is carried out, and the accuracy is cumulatively optimized. The batching accuracy far exceeds that under manual adjustment. Specifically, the dynamic correction steps are as follows:

[0072] First, set the weight value in the batching stage. Set the medium feeding amount to 5KG, the slow feeding amount to 2KG, the fine feeding amount to 0.5KG, and the lead to 0.04KG.

[0073] S1: The weight of the powder material in the silo is 200KG, the target weight is 150KG, and the silo weight is greater than the target weight, so start fixed-value batching.

[0074] S2: Determine whether the stability difference of the weighing instrument is less than the stability limit value. For example, if the fluctuation error of the weighing instrument is 0.02KG and the stability limit value is 0.04KG, when the stability difference is less than the stability limit value, collect the weight of 200KG of the current weighing instrument as the weight before batching.

[0075] S3. Start the weighing instrument to return to zero (i.e., tare the current weight); open the cutting valve; start the spiral servo to feed quickly, and the spiral conveys the powder material in the silo through the cutting valve; the stirring motor runs intermittently at the set speed; start the fixed-value batching timing;

[0076] S4. In the rapid feeding stage, the method of cascade PID control and time prediction is used to adaptively adjust the spiral servo speed. The initial value of the spiral servo speed is set to V s , and the batching weight range of the cascade PID control is m d =m t –m t3 , and the current batching speed V p =m d / t b , where m t is the target weight, m t3 is the weight of the fine feeding amount. The rapid feeding stage has little impact on batching overrun but has a greater impact on batching time. Therefore, it is not necessary to control frequently and the t value can be taken larger. Take t as 1S, and the control strategy is as follows:

[0077] 1. Calculate the PWM of the duty cycle of the spiral servo speed V s , PWM = 120 / 150 = 86.7%;

[0078] 2. Outer loop PID control. In the Siemens PLC environment, take the actual batching weight m p as the actual measured value, and the value obtained by subtracting the fine feeding amount from the target weight as the set value m d = 200 - 0.5 = 195. Only the proportional coefficient term P of the control parameters is used. When adjusting the parameters, first adjust the inner loop, and then adjust the outer loop. Adjust the outer loop to the appropriate P to ensure the rapid adjustment of the spiral servo speed. Under the adjustment of P, the output control quantity V n is obtained;

[0079] 3. Inner loop PID control. In the Siemens PLC environment, take the V n obtained in step 2 as the set value, and the PWM of the duty cycle of the current spiral servo speed V s as the actual measured value. Only the proportional coefficient term P of the control parameters is used. Under the adjustment of P, the output control quantity V u ＇ is obtained. When adjusting the parameters, first disconnect the outer loop, adjust to the appropriate P to ensure the rapid adjustment of the spiral servo speed. At the same time, to ensure that the batching speed does not increase too much, an upper limit value can be set for the maximum value V p of the spiral servo speed, such as taking 80 - 90% of the maximum speed;

[0080] 4. Take the output V u ＇Convert the duty cycle to the helical servo speed V u , V u = V u ＇ * 150;

[0081] 5. Set V u as the new helical servo speed and return to step 1.

[0082] Because the actual batching speed V p is mainly adjusted by the helical servo speed, the mixing speed has a relatively small impact on the actual batching speed V p . The mixing speed refers to the change of the helical servo and is adjusted synchronously in a certain proportion.

[0083] S5. When the batching weight is greater than or equal to the target weight minus the medium feeding amount, enter the medium-speed feeding stage, turn off the mixing motor. In the medium-speed feeding stage, continue to use the cascade PID model in the fast feeding stage. The value of t b is taken to be slightly smaller than that in the fast feeding, and t b is taken as 0.5S.

[0084] S6. When the batching weight is greater than or equal to the target weight minus the slow feeding amount, enter the slow feeding process, continue to use the cascade PID model in the fast feeding stage. The value of t b is taken to be slightly smaller than that in the medium-speed feeding, and t b is taken as 0.2S.

[0085] S7. In the slow feeding stage, predict the fixed-value batching time. Predict the fixed-value batching time t = t0 + t p + t j ;

[0086] t0 is the current fixed-value batching timing time, t p is the predicted time for the uncompleted fixed-value batching in the third-speed feeding stage, and t j is the predicted time for the jog feeding process;

[0087] t p =(m t - m t0 - m t3 ) / V u ;

[0088] Among them, m t is the target weight, V u is the predicted batching speed, m t0 is the current actual batching weight, and m t3 is the weight of the fine feeding amount.

[0089] Set the jog time as t1 and the interval time as t 2， Then t j =(mt3 / V j )*(t1 / (t1 + t2)).

[0090] V j For the batching speed during the jogging process, take the batching speed during the previous fixed-value batching jogging. Let m tj1 , m tj0 be the weights at the moments before and after the start of a single jogging respectively. Then V j = (m tj1 - m tj0 ) / t1. In the formula, m tj1 , m tj0 are the weights at the moments before and after the start of a single jogging respectively, and t1 is the single jogging time.

[0091] When the material fluidity changes and the cascade PID control cannot meet the accuracy requirements, time prediction is required as a feedforward and cascade PID for collaborative control and dynamic optimization of key parameters. In this way, through this calculation of time prediction, the overall performance of the system can be improved.

[0092] If the predicted fixed-value batching time t is lower than the optimal range value, then when the fixed-value batching time t is equal to the minimum value of the optimal range value, close the slow feeding and start the spiral servo to enter the jogging feeding.

[0093] If the predicted fixed-value batching time t exceeds the optimal range value, then when the batching weight is greater than or equal to the target weight minus the fine feeding amount, delay entering the jogging feeding stage. The delay amount is taken as a multiple of the minimum accuracy of the weighing instrument. For example, take 5 times, that is, 0.02 * 5 = 0.1

[0094] If the predicted fixed-value batching time t is within the optimal range value, then judge whether the batching weight is greater than or equal to the target weight minus the fine feeding amount. When the batching weight is greater than or equal to the target weight minus the fine feeding amount, close the slow feeding and start the spiral servo to enter the jogging feeding step;

[0095] S8. During the jogging feeding process, judge whether the batching weight is greater than or equal to the target weight minus the lead amount, and then judge whether the batching weight increases within n jogging cycles. According to experience, the n value is taken around 5.

[0096] S9. When the batching weight is greater than or equal to the target weight minus the lead amount and the batching weight increases within n jogging cycles, continue to judge whether the batching weight is greater than or equal to the target weight;

[0097] S10. When the batching weight is greater than or equal to the target weight, or when the batching weight is greater than or equal to the target weight minus the lead amount and the batching weight does not increase within n jogging cycles, the fixed-value batching is completed, close the spiral servo and start the jogging feeding;

[0098] S11. Determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight after batching; otherwise, give an alarm prompt.

[0099] S12. Take the absolute value of the weight before batching minus the absolute value of the weight after batching as the batching error, and determine whether the absolute value of the batching error is less than or equal to the allowable batching error. The allowable batching error is generally determined according to process and quality standard specifications. When the absolute value of the batching error is less than or equal to the allowable batching error, it is determined that the batching is normal; otherwise, it is determined that the batching is out of tolerance.

[0100] The present application also provides a fixed-value batching system for powder materials, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the above method are implemented. This fixed-value batching system for powder materials can implement each embodiment of the above-mentioned fixed-value batching method for powder materials and can achieve the same beneficial effects, which will not be elaborated here.

[0101] As mentioned above, it is only the specific implementation manner or the description of the specific implementation manner of the present invention. The protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should be covered within the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for fixed-value batching of powder materials, characterized in that, Including: S1: When the weight of the powder material in the silo is greater than the target weight, start the fixed-value batching program; S2: Determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight before batching, otherwise give an alarm prompt; S3: Adjust the batching device, start the fixed-value batching timing, control the batching device to enter the feeding stage at the first speed, and execute the first control strategy; when the batching weight is greater than or equal to the first target weight, enter the feeding stage at the second speed, and execute the second control strategy; when the batching weight is greater than or equal to the second target weight, enter the feeding stage at the third speed, and execute the third control strategy; predict the fixed-value batching time in the third-speed feeding stage, and execute the jog feeding process according to the predicted fixed-value batching time; the first speed is greater than the second speed, and the second speed is greater than the third speed; S4: After the jog feeding process ends, determine whether the stability difference of the weighing instrument is less than the stability limit value. When the stability difference is less than the stability limit value, collect the weight of the current weighing instrument as the weight after batching, otherwise give an alarm prompt; S5: Take the absolute value of the weight before batching minus the absolute value of the weight after batching as the batching error. If the absolute value of the batching error is less than or equal to the allowable batching error, it is determined that the batching is normal, otherwise it is determined that the batching is out of tolerance.

2. The metering and batching method for powder materials according to claim 1, wherein The first control strategy, the second control strategy, and the third control strategy all include a cascade PID control model, and the cascade PID control model is as follows: S11: Calculate the helical servo speed V s The PWM of the duty cycle, where PWM = batching speed / maximum rotational speed of the servo motor operation; S12: For the outer-loop PID control, use the actual batching weight m p as the actual measured value, use the value obtained by subtracting the fine feeding amount from the target weight as the set value, use the proportional coefficient term P as the control parameter. When adjusting the control parameter, first adjust the inner loop, then adjust the outer loop, adjust the outer loop to the required P, and obtain the output control quantity V under the adjustment of the control parameter P n ; S13: For the inner-loop PID control, take the output control quantity V n as the set value, and the current spiral servo speed V s duty cycle PWM as the actual measured value. Use the proportional coefficient term P as the control parameter. When adjusting the control parameter, first disconnect the outer loop, adjust to the required P, and obtain the output control quantity V under the adjustment of the control parameter P u ＇ , and set the upper limit value V p ; S14: Convert the output V obtained from the inner loop u ＇ into the helical servo speed V u , where V u = V u ＇ * batching speed range max ; S15: Set the spiral servo speed V u to the new spiral servo speed, and return to S11 for iteration until entering the next feeding stage.

3. The fixed-value batching method for powder materials according to claim 2, wherein Controlling the batching device to enter the feeding stage at the first speed and executing the first control strategy includes: During the feeding stage at the first speed, the cascade PID control method is used to adjust the spiral servo speed, and the initial value of the spiral servo speed is set to V s , and the batching weight range for PID control is m d , where m d = m t – m t1 , the current batching speed is V p， V p = m d / t b , t b represents the step size, where m t is the target weight and m t1 is the weight of the medium feeding amount; Calling the cascade PID control model to execute the control.

4. The fixed-value batching method for powder materials according to claim 2, characterized in that Entering the feeding stage at the second speed and executing the second control strategy includes: Enter the feeding stage at the second speed, turn off the stirring motor, and set the initial value of the spiral servo speed to V s , the weighing range of the batching controlled by PID is m d , where m d = m t – m t2 , the current batching speed is V p， V p = m d / t b , t b represents the step size, where m t is the target weight, m t2 is the weight of slow feeding, and set the value of the step size t b to be less than the step size t in the feeding stage at the first speed b , and continue to call the cascade PID control model to perform control.

5. The metering and batching method for powder materials according to claim 2, characterized in that, Entering the feeding stage at the third speed and executing the third control strategy includes: Enter the feeding stage at the third speed, and set the initial value of the screw servo speed to V s , and the batching weight range for PID control is m d , where m d = m t – m t3 , the current batching speed is V p， V p = m d / t b , t b represents the step size, where m t is the target weight, m t3 is the weight of the fine feeding amount, and set the value of the step size t b to be less than the step size t in the feeding stage at the second speed b , and continue to call the cascade PID control model to execute the control.

6. The metering batching method for powder materials according to claim 1, wherein, Predicting the fixed-value batching time t in the third-speed feeding stage satisfies the following relationship: Predicting the fixed-value batching time in the third-speed feeding stage satisfies the following relationship: t = t0 + t p + t j ; where t0 is the current fixed-value batching timing time, t p is the predicted time for the fixed-value batching not completed in the third-speed feeding stage, t j is the predicted time for the jog feeding process; t p Satisfies the following relationship: t p = (m t - m t0 - m t3 ) / V u ; where m t is the target weight, V u is the predicted batching speed, m t0 is the current actual batching weight, m t3 is the weight of the fine feeding amount; t j Satisfies the following relationship: t j = (m t3 / V j ) * (t1 / (t1 + t2)); Wherein, V j is the batching speed during the jogging process, which takes the batching speed during the previous fixed-value batching jogging. t1 is the single jogging time, and t2 is the single interval time; V j Satisfies the following relational expression: V j = (m tj1 - m tj0 ) / t1; where m tj1 and m tj0 are the weights at the moments before and after the start of a single jogging respectively, and t1 is the single jogging time.

7. The metering batching method for powder materials according to claim 6, characterized in that, Executing the jog feeding process according to the predicted fixed-value batching time t includes: If the predicted fixed-value batching time t is lower than the set optimal range value, then when the fixed-value batching time t is equal to the minimum value of the optimal range value, close the feeding at the third speed and start the screw servo to enter the jog feeding step; If the predicted fixed-value batching time t exceeds the set optimal range value, then when the batching weight is greater than or equal to the target weight minus the fine feeding amount, delay entering the jog feeding step, and the delay amount is the time delay or the reduction of the fine feeding amount, and the delay amount is set according to the difference between the predicted fixed-value batching time t and the optimal range value; If the predicted fixed-value batching time t is within the optimal range value, then when the batching weight is greater than or equal to the target weight minus the fine feeding amount, close the feeding at the third speed and start the screw servo to enter the jog feeding step; The jog feeding step is as follows: Judge whether the batching weight is greater than or equal to the target weight minus the lead, and then judge whether the batching weight increases within n jogging cycles. When the batching weight is greater than or equal to the target weight minus the lead and the batching weight increases within n jogging cycles, continue to judge whether the increased batching weight is greater than or equal to the target weight; When the batching weight is greater than or equal to the target weight, or when the batching weight is greater than or equal to the target weight minus the lead and the batching weight does not increase within n jogging cycles, the fixed-value batching is completed, and the screw servo and jogging feeding are turned off.

8. The fixed-value batching method for powder materials according to claim 1, characterized in that The described batching device adjustment includes: Start the weighing instrument to return to zero, open the cut-off valve, the screw servo starts feeding at the first speed, control the screw to convey the powder material in the silo through the cut-off valve, and control the stirring motor to run intermittently at the set speed.

9. A fixed-value batching system for powder materials, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it realizes the steps of the method described in any one of claims 1 to 8 above.

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