Study On Processing And Mechanism Of Solid Conveying And Compaction In Vane Extruder

Extrusion molding is one of the most important molding methods for polymer processing. At present, screw machinery is widely applied to the polymer extrusion processing. However, the plasticizing and conveying mechanism of the traditional screw extruder is based on the shear rheology, in which the materials suffer the effect of shear stress. There are some common disadvantages in the extrusion equipment dominated by shear rheology, such as long thermo-mechanical processing, high energy consumption, huge volume, transport process depended on material properties, and so on. The Polymer Vane Extruder, which is newly designed by Prof. Qu Jinping in SCUT, is a novel equipment for polymer processing. Its plasticizing and conveying mechanism is dominated by elongational flow. It can solve the problems existed in the traditional screw extruder. The Polymer Vane Extruder is a major breakthrough and innovation, so it brings significant effect on the theory of extrusion molding.This paper mainly studies on the mechanism of solid conveying and compaction in the vane extruder. According to structural and technical characteristics of the vane extruder, the solid conveying and compaction model between the two vanes was established and the analytical results of the model were obtained. It expressed the relationship between the pressure of the material and the structural parameters of the conveying unit, the processing parameters and the parameters of the materials'properties.In order to verify the theoretical model, we designed a visual experimental device. Several experiments were designed to study the effect of the parameters on solid conveying and compaction processing by changing temperatures, eccentricities, the discharging way of the materials, different materials and speeds. According to the analysis of these results, we obtained that: 1) the comparison of the results obtained from the theoretical calculation and the experiment revealed that the theoretical model was valid and useful; 2) the pressure of particulate solids decreased with the rising of the temperature and the angel of the discharging gap and increased with the rising of the eccentricity; 3) the compression rate of crystalline materials was lower than that of non-crystalline materials; 4) at low rotating speed, the pressure increased as the rotating speed increased, but at high rotating speed, it made no sense.The theoretical model and the pressure variation regular proposed in this paper could provide important theoretical basis for the design of the vane extruder and production practice.