On modeling the solids conveying zone of a plasticating extruder

Abstract

A model for the solids conveying zone of a plasticating extruder is presented. The flow of solid granules is studied in the framework ofthermomechanics of media with affine structure, and assimilated to plane steady flow of an incompressible viscous fluid with spherical indeformable structure. Simple constitutive equations are accepted, along with those kinematical assumptions which stem directly from the geometry of the system. The resulting balance equations are given a dimensionless form, and integrated so as to arrive at closed-form solutions for velocity, spin and temperature of granules. A discussion of the influence of the adimensional parameters relevant to the problem is presented; this discussion is supplemented with some examples. Finally, various developments and refinements of the present model are proposed.* Most n f the results contained In the present nnte were the object 01 a communication presented at the Joint Meeting ofthe British, Netherlands and Italian Societies nt Rheology on Polymer Processing and Rheometry, Pisa 13th-15th April 1977, under the title: "Thermomechanics of plasticating extrusion: 1-Solids conveying znne " ' By solids conveyingzone we mean the zone from the section where the unld granular polymer IS supplied througlr the Impper to the section where firstly melting occurs.'The importance nt alluwing tor shearing flow in the solid fed 1s pointed nut by Pearsnn (2). in contrast, current theories derived from Darnell and Mol see the solid fed as a plug which rigidly slides down the channel. The reader IS referred to Ref. (5). Ch. 4, lor an exposition of the theory of Darnell and Ma1 (61, later extended by Schneider (7); the analysis nl Lovegrove and Williams (8), which develops along the same basic ideas, IS summarized briefly by Pearsnn in Ref.(1). 8 The need for a rational basis of rules for scale-up is stressed by Pearson in Ref. (1,2).

Modelling method for studying solid conveying process in inclined plastication unit

“…However, solid plug and solid bed were used to describe the process. 5,6 Recently, non-plug solid conveying mechanisms have been observed in visualisation experiments. 7,8 Simulations of the non-plug solid conveying process are also conducted.…”

“…1,2 Investigations on the process of microinjection moulding have up to now been mainly on the mould filling process. [3][4][5] Studies on other important related issues that also affect product quality such as plastication and solid conveying in microinjection moulding machines are very few. This is probably because most studies are carried out using commercially available traditional machines.…”