Study On The Screws Configuration For UPVC Injection Molding

Polyvinyl chloride (PVC) is a kind of general colophony. UPVC is PVC which has no plasticizing agent added. Owing to the superiority of the injection production, the quantity of UPVC products by injection molding is only less than that by extrusion for the present.Recently, the demand for UPVC injection products, especially pipe fittings have been increasingly rising. While the general injection molding screw used for UPVC injection molding has poor mixing performance and plasticizing capacity. As a result, melting UPVC usually decomposes for overheating or residence, which has extremely restricted the improvement in injection efficiency and can not satisfy the market demands for high quality and property. Consequently, the thesis utilized POLYFLOW software which was based on finite element analysis computational fluid dynamics (CFD) to simulate melt body in the measurement section flow channel. Pressure field, velocity field, shear-rate field, viscosity field and shear-stress field would be solved by simulation.This paper discussed seven kinds of screws configuration. Two kinds of columned pin mixing screws, rectangular pin mixing screw and two kinds of lead rhombic pin mixing screws included. Columned pins can arrange in two ways that pins lined along the axes and crossed along the axes. The study indicated that the undulation screw's mixing performance and transportation ability were eminent according to analyzing results. The pin mixing screws were superior to the general screw to be fit for UPVC injection molding on account of its better distributive mixing effect and dispersive mixing effect. The phenomena that melt body residence in all screws can not tack place. So the undulation screw would be chose to inject UPVC firstly.