Plastic extruder control system control system

Plastic extrusion machine control systems control systems including heating systems, cooling systems and process parameter measurement system, mainly by the electrical, instrumentation and actuators (ie, control panel and console) composition. Its main role is: to control and regulate the main auxiliary drive motor, the output meet the technical requirements of speed and power, and enable coordination of main and auxiliary; detect and adjust the temperature of the plastic extrusion machine, pressure, flow rate; to achieve control of the entire unit or automatic control. Extruder drive electrical control can be divided into two parts, control and temperature control, to achieve the extrusion process, including temperature, pressure, screw rpm, cooling screw, barrel cooling, product cooling and diameter control, and traction speed, neat cable on the reel and to ensure an empty plate to full plate from the constant tension take-up control. One set of screw speed control is the core of the device. Screw speed and stability in the regulation of the host drive one of the important process requirements. Screw speed and directly determine the volume of the plastic extrusion speed, normal production always want the highest possible speed and to achieve high yield, the extruder screw speed requirements from the start to the desired operating speed, the available speed range to be large. And stability requirements for high speed, because speed fluctuations will lead to fluctuations in the amount of extrusion, impact extrusion quality, so there is no change in the traction line speed case, the change will cause the cable diameter. Similarly, such as wire-speed traction devices can also cause large fluctuations in the changes in cable diameter, screw speed and traction stage through the operation reflected the appropriate instrumentation, extrusion should be closely observed to ensure high yield.
Plastic Machinery shortcomings of traditional control systems:
(1) in the traditional screw extruder systems, screw driven by a DC motor. In the case of direct drive screw directly driven by a gear box; in the case of indirect drive, screw driven by a belt drive and traction. The traditional DC motor itself, there are some drawbacks: for example, the brush DC motor to be replaced once a month, in the dusty or corrosive environment DC motor requires frequent cleaning, and sometimes even need to shop outside of DC motor through into the clean cool air.
(2) indirect drive screw extruder drawback: the existence of belt slip, belt will cause some energy loss, more wear and mechanical devices increases the possibility of failures. The biggest drawbacks of DC motor noise is too large, brush sparking, rotor pollution, motor temperature is too high, inadequate exhaust and electrical shock. Therefore, using the DC motor-screw extruder higher maintenance costs, the initial cost of DC motor higher.
Fourth, the frequency transformation implementation. SAJ-8000 series inverter for extrusion equipment, high-quality performance characteristics, which is due to vector-controlled inverter itself can provide good performance decision.
A high-performance CPU to provide higher frequency response SAJ-8000 series inverter built-in high-speed CPU, high control precision, fast response frequency performance. Extruder process is mainly required outlet pressure constant control equipment at the beginning of work, the speed control, demand pressure is reached, we should switch to pressure control. Switching process should be no impact, need to control the high frequency accuracy, the pressure signal to collusion.
2 Vector Control provides high torque output at low frequencies of the main extruder drive motor, mainly through reduction parallel shaft helical gear reducer drive after turning the screw, the following changes in the fundamental frequency constant torque when the speed governor. Past use of V / F control frequency, due to start considering the load torque, torque to set the corresponding bit to enhance the level, if the torque boost setting is too high, the low-frequency excitation light load will too easily lead to Motor severe fever, affects the stable operation of the device.
The use of speed sensorless vector inverter SAJ-8000 series, use the learning function can be observed from the motor parameters, not only good at low frequencies the motor output characteristics, inverter to run their own energy-saving feature will automatically change with reduced torque output current, not only can save energy, better to eliminate the likelihood of the above-mentioned risks.
3 torque limit and slip compensation structure is automatically set according to motor, speed control accuracy up to 0.1%.