Double Order Extrusion Process Dynamic Characteristics And Control Methods Research

Supercritical carbon dioxide XPS PS insulation board production technology is advanced production technology in the XPS industry. It usually adopts double order extrusion system, the first order is twin-screw extruder and the second order is single-screw extruder. The higher connection body pressure is helpful for the mix of carbon dioxide. Keeping stable connected body pressure within the scope of melt pressure of twin-screw extruder is one of the key problems urgently to be solved.In this study, the connected body pressure is the research object. A set of data acquisition system that based on PLC, configuration software, Ethernet communication and Modbus communication was independent developed and it has been applied to double order extrusion system. Using this system acquire analogues such as speed, pressur, torque, temperature etc and associated power parameters such as power and energy.The connected body pressure is concerned with twin-screw speed, single-screw speed and feed speed and double order extrusion system is a multiple inputs multiple outputs problem. The traditional transfer function method is not be used for solving the multivariable systems. This paper built a more precise three input and one output state space model of double order extrusion system first time under the help of numerical state space subspace system identification methods (N4SID). It opened three input channels in the model and makes us have conditions to study dynamic relationship and simulation between three inputs and one output.The PID closed-loop control based on state space model of the double order extrusion system was established in MATLAB environment. PID parameters were setted by using the method of stability borders and the connection body pressure had very good stability in value. The other two inputs'disturbance as input was introduced into the other two control channels of the state space model to analyse system robustness and the input weight to output. The guiding conclusion to actual engineering is that the connected body pressure is sensitive to single-screw speed, and single-screw speed—connected body pressure closed-loop PID control has a more advantage than other closed-loop control system, if select feeding speed-connected body pressure closed-loop PID control system, we should maintain constant single-screw speed as much as possible.