An optimization method for stable start-up control mode of extruder

Abstract

The invention discloses an optimization method for a stable start-up control mode of an extruder, which adjusts the start-up operation mode from a mass mode to a volume mode, and configures a drive command control limit in a DCS. In the volume mode, the drive command of the additive to the rotary valve frequency converter is determined by the feed setting value, and the drive command is linearly proportional to the load, that is, when the load is set to 20T, the corresponding drive command is 20%, and the rotary valve speed is also linearly proportional to the drive command, that is, when the drive command is 8%, the rotary valve speed is 2r / min, and when the drive command is 18%, the rotary valve speed is 4.7r / min. The rotary valve speed changes with the change of the load. When starting in the volume mode, after the setting program is completed, the load is manually increased, the rotary valve speed gradually increases, the material discharge amount increases accordingly, and the torque of the main motor changes smoothly.

Description

Technical Field

[0001] The invention belongs to the technical field, and in particular relates to an optimization method for a stable start-up control mode of an extruder. Background Art

[0002] The original design of the PP unit extruder used the "quality control" mode for start-up and operation. Specifically, the powder scale W801 installed at the inlet of the extruder was used to measure the real-time discharge amount, and the measured value was fed back to the powder system PLC control system through the powder weighing system, and a PID control loop was formed with the discharge amount set by the extruder PLC system. The discharge amount was controlled by adjusting the speed of the discharge valve.

[0003] When W801 is in quality mode, the output command of the additive to the rotary valve inverter is determined by the deviation between the actual measurement MF of the material discharge and the set value SP, that is: when MF is less than SP, the drive command increases and the rotary valve speed increases accordingly; when MF is greater than SP, the drive command decreases and the rotary valve speed decreases accordingly, thereby controlling the amount of material discharge.

[0004] Quality mode start-up requires extremely high accuracy of the W801 sensor. The rotary valve speed is greatly affected by the detection value MF of the material discharge scale. If there is a deviation in the measurement of the material discharge scale, the rotary valve speed will be continuously adjusted, and the actual material discharge amount will also follow the changes, eventually causing the main motor torque to fluctuate and even interlock jump. The start-up process is subject to one point MF, which is very risky.

[0005] When the quality mode is started, the W801 weighing sensor has higher requirements, so it is necessary to automatically backflush and peel regularly to reduce the weighing deviation. However, weighing deviation is prone to occur during each purge process, which causes load fluctuations and is not conducive to the stable operation of the extruder under high-melting fat products. Summary of the invention

[0006] In view of the above-mentioned problems, the object of the present invention is to provide an optimization method for the stable start-up control mode of an extruder.

[0007] The technical solution of the present invention is: an optimization method for a stable start-up control mode of an extruder, comprising the following steps:

[0008] S1: Adjust the extruder start-up mode from mass mode to volume mode;

[0009] S2: The extruder is started in volume mode. The driving command of the MCC inverter of the extruder unloading valve is determined by the operator's load setting value. The operator's load setting value and the unloading volume flow value measured by the weighing instrument are calculated by the additive PLC system and output to the additive system KCM control block. The additive system KCM control block outputs a 0-100 driving command to the MCC inverter. The MCC inverter outputs a 0-50Hz frequency signal to the unloading valve motor. The unloading valve motor controls the amount of unloading by adjusting the speed.

[0010] S3: Manually increase the load setting value, the speed of the unloading valve motor increases gradually, the unloading amount increases accordingly, and the torque of the unloading valve motor changes steadily;

[0011] S4: Measure the volume flow value of the material through the weighing instrument and output it to the additive PLC system for calculation.

[0012] Furthermore, in S2, the driving command is linearly proportional to the load, that is, when the load is set to 20T, the corresponding driving command is 20%, and the speed of the unloading valve is also linearly proportional to the driving command, that is, when the driving command is 8%, the speed of the unloading valve is 2r / min, and when the driving command is 18%, the speed of the unloading valve is 4.7r / min. The speed of the unloading valve changes with the change of the load.

[0013] Furthermore, the load=rotor speed of unloading valve*volume*filling rate*stacking density*time.

[0014] Furthermore, when there is an abnormality in material unloading or the control of the unloading rotary valve is out of adjustment, the maximum drive command can be limited to 70% through the limit set by the DCS, thereby ensuring that the torque of the extruder main motor does not exceed the limit, ensuring both the stable operation of the device and the safety of the equipment.

[0015] Furthermore, a manual / cascade switching button is added. When the weighing instrument fluctuates greatly, the speed of the unloading valve cannot be controlled, and the torque of the extruder jumps, the process operator can switch the unloading mode from cascade to manual control according to the actual situation, thereby ensuring the stability of the unloading valve speed and unloading.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Solve the problem that the stable operation of the extruder is restricted by the measurement accuracy of the weighing instrument, so that the operation of the extruder is less affected by the weighing stability of the weighing instrument;

[0018] 2. Solve the problem that the fluctuation of weighing instrument during the extruder start-up affects the start-up success rate;

[0019] 3. Solve the problem that the measurement fluctuation of the weighing instrument during the operation of the extruder causes the speed jump of the unloading valve, which ultimately leads to the torque fluctuation of the main motor of the extruder;

[0020] 4. Improve the success rate of extruder start-up and ensure long-term stable operation of the unit;

[0021] 5. The material unloading control is stable during the operation, which is conducive to load torque control and brand switching;

[0022] 6. The system outputs relatively stable instructions to the frequency converter, so the rotary valve will not be adjusted frequently, which is conducive to the stable operation of the equipment;

[0023] 7. Since the weighing value of the weighing instrument is only used as a reference and does not participate in the speed control, the sensor does not need to be purged frequently and the material load will not fluctuate;

[0024] 8. Sudden failure of the weighing sensor will not affect the normal operation of the extruder; BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the feeder unloading control of the present invention. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0027] Example: Figure 1 As shown, a method for optimizing a stable start-up control mode of an extruder comprises the following steps:

[0028] S1: Adjust the extruder start-up mode from mass mode to volume mode;

[0029] S2: The extruder is started in volume mode. The MCC inverter drive command of the extruder unloading valve is determined by the operator's load setting value. The operator's load setting value and the unloading volume flow value measured by the weighing instrument are calculated by the additive PLC system and output to the additive system KCM control block. The additive system KCM control block outputs a 0-100 drive command to the MCC inverter. The MCC inverter outputs a 0-50Hz frequency signal to the unloading valve motor. The unloading valve motor controls the amount of unloading by adjusting the speed.

[0030] S3: Manually increase the load setting value, the speed of the unloading valve motor increases gradually, the unloading amount increases accordingly, and the torque of the unloading valve motor changes steadily;

[0031] S4: Measure the volume flow value of the material through the weighing instrument and output it to the additive PLC system for calculation.

[0032] The driving command is linearly proportional to the load, that is, when the load is set to 20T, the corresponding driving command is 20%. The speed of the unloading valve is also linearly proportional to the driving command, that is, when the driving command is 8%, the speed of the unloading valve is 2r / min, and when the driving command is 18%, the speed of the unloading valve is 4.7r / min. The speed of the unloading valve changes with the change of load.

[0033] Load = feed valve speed * volume * filling rate * stacking density * time. The corresponding relationship of each parameter is shown in the following table:

[0034]

[0035] When there is an abnormality in material unloading or the control of the unloading rotary valve is out of adjustment, the maximum drive command can be limited to 70% through the limit set by the DCS, thereby ensuring that the torque of the extruder main motor does not exceed the limit, ensuring both the stable operation of the device and the safety of the equipment.

[0036] Add the function of manual / cascade switching button. When the weighing instrument fluctuates greatly, the speed of the discharge valve cannot be controlled, and the torque of the extruder jumps, the process operator can switch the discharge mode from cascade to manual control according to the actual situation, so as to ensure the stability of the discharge valve speed and discharge.

[0037] The specific models of the above electronic components are not specially specified, and ordinary products available on the market can be selected as long as they can meet the use requirements of the present invention.

[0038] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. An optimization method for a stable start-up control mode of an extruder, characterized in that: The following steps are involved: S1: Adjust the extruder start-up mode from mass mode to volume mode; S2: The extruder is started in volume mode. The MCC inverter drive command of the extruder unloading valve is determined by the operator's load setting value. The operator's load setting value and the unloading volume flow value measured by the weighing instrument are calculated by the additive PLC system and output to the additive system KCM control block. The additive system KCM control block outputs a 0-100 drive command to the MCC inverter. The MCC inverter outputs a 0-50Hz frequency signal to the unloading valve motor. The unloading valve motor controls the amount of unloading by adjusting the speed. S3: Manually increase the load setting value, the speed of the unloading valve motor increases gradually, the unloading amount increases accordingly, and the torque of the unloading valve motor changes steadily; S4: Measure the volume flow value of the material through the weighing instrument and output it to the additive PLC system for calculation; In S2, the driving command is linearly proportional to the load, that is, when the load is set to 20T, the corresponding driving command is 20%. The speed of the unloading valve is also linearly proportional to the driving command, that is, when the driving command is 8%, the speed of the unloading valve is 2r / min, and when the driving command is 18%, the speed of the unloading valve is 4.7r / min. The speed of the unloading valve changes with the change of the load. The load = feed valve speed * volume * filling rate * bulk density * time; When the unloading is abnormal or the unloading valve control is out of adjustment, the maximum drive command is limited to 70% through the limit set by the DCS; A manual / cascade switching button is added to the unloading valve. When the weighing instrument fluctuates greatly, the speed of the unloading valve cannot be controlled, and the torque of the extruder jumps, the process operator switches the unloading mode from cascade to manual control according to the actual situation.

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