The Research And Realization Of A Control System For Plastics Extrusion Lines

Automation system is extension in plastics extrusion lines. The aim is to supervise and control all of the important parameters. Computer control system is often used to increase stability and reliability of processing equipment.This thesis mainly discussed from the point of application, to resolve problems coming from production process. Firstly it introduces the principal and the process of the plastics pipe extrusion equipment, and based on the foundation a control idea and a control scheme were put forward. Based the principal of PID and its parameters' tuning algorithm, the "on-off" control principal of the relay, a PID-Relay control algorithm of temperature in the plastics pipe extrusion was introduced. Programmable Logic Controller (PLC) is used to design the control system of process equipment. The Siemens S7 series PLC was applied in to collecting data and executing action. The programmable software is STEP7. Configuration software WinCC runs in a monitor computer. Based the PLC-DCS control system in plastics pipe extrusion equipment, the system configuration was completed finished and the control software was programmed. The WinCC was used to develop human-machine interface to supervise the whole plastics pipe extrusion equipment.The control system has gained a good result. It satisfies the request of production process. In temperature control, the overshoot is less than 2℃,the state error is no more than ±0.5℃. It increases the reliability and anti-jamming ability. Meanwhile, the user-friendly interface makes the operator to master the whole system in a short time.