Posted by
useongroup on Tuesday, July 07, 2009 10:40:05 PM
Plastic injection molding machine that can be classified as
reciprocating
extruder are among the most widely used machines in industry.
However, most studies in the injector design were based on steady state models
developed for
reciprocating
extruder that involved no reciprocation. This over-simplified
model leaves out the most important aspect of reciprocation. The authors of this
paper have derived a transient melting model that takes care of the change from
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 rate dependent. The result has shown that
screw rotation speed, screw axial movement speed, barrel thickness, barrel heat
capacity, temperature of heater and polymer are factors affecting the melting
speed and the transient effects.