Simulation of transient process in melting section of reciprocating extruder

Plastic injection molding machine that can be classified as reciprocating e xtruders are among the most widely used machines in industry. However, most studies in the injector design were based on steady state models developed for extruders that involved no reciprocation. This over-simplified model l eaves out the most important aspect of reciprocation. The authors of this p aper have derived a transient melting model that takes care of the change f rom the conventional steady extrusion to that of a discontinuous transient process. This paper describes simulations conducted on the derived model to explain observation that cannot be explained by the steady extrusion model in practical experiments. The simulation was conducted by using parameters given in Donovan's experiment [Polym Engng, 11 (1971) 353]. The simulation results are found to qualitatively match with the experimental results. It proves the validity of the model. Simulation has also been conducted with the model on materials that their viscosities are temperature and shear rat e dependent. The result has shown that screw rotation speed, screw axial mo vement speed, barrel thickness, barrel heat capacity, temperature of heater and polymer are factors affecting the melting speed and the transient effe cts. (C) 2001 Elsevier Science Ltd. All rights reserved.