Identification of transient responses of a plasticating twin screw extruder due to excitation in feed rate

Abstract

A corotating plasticating twin screw extruder (TSE) was excited by changing feed rate according to predesigned random binary sequence (RBS) and stair type excitation. A high density polyethylene was used as processing material in this study. Empirical models were developed relating two output variables, melt pressure at die (Pm), and melt temperature at die (Tm), with feed rate (F). Classical linear system identification technique was used to develop models. Models were developed using a data set obtained from RBS excitation. Stair type excitation data were used to validate the developed models. The structure of the obtained models was autoregressive moving average with exogenous input (ARMAX). Models with ARMAX structure and order of 2 were found to be sufficient to capture the dynamic behaviors of Pm and Tm when F was changed. A delay‐gain model was proposed for Pm and was found to capture the response quite satisfactorily. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

Small-Scale Mechanical Recycling of Solid Plastic Wastes: A Review of PET, PEs, and PP

“…Hence an optimal operational setting is needed for both energy conservation and extrudate quality. Relationships between melt temperature, screw speed, and feed rate have been studied in the past for the twin-screw extruder using predictive model controllers [194]. Nevertheless, the method used was not developed under processing conditions and was designed for the twin-screw extruder.…”

Dynamic gray‐box modeling for on‐line monitoring of polymer extrusion viscosity

“…It is noted that similar work has been reported recently in [9,10] which developed dynamic gray-box models relating melt pressure and melt temperature to screw speed (or feed rate) along with random binary sequence (or stair) type excitation for twin screw extrusion. Different from [9,10], in this study, four input variables including three barrel temperatures and screw speed, have been excited simultaneously with a predesigned pseudorandom signal (PRS) and hence a wide range of operating conditions has been covered for a single screw extruder. Both pressure model and viscosity model have been developed based on dynamic gray-box models acting as a soft sensor for viscosity monitoring.…”