Extrusion Simulation And Analysis Design Of ABS Coat-hanger Die

Coat-hanger die is widely used in the extrusion of plate and sheet due to its large divergence angle which can achieve uniform velocity attribution on the outlet and decrease pressure-drop, however, most of domestic die design and manufacturing enterprises use trial-and-error method which is costly and time-consuming to design coat-hanger die, so the study of coat-hanger die is of great importance.Die cave structure equations were deduced in this paper with manifold entrance radius as parameter in accordance with the principle of uniform pressure drop of each streamline. The structure equations were verified by the method of numerical simulation which was done by finite element software Polyflow with structured grid meshed by ICEM. The results showed that the uniform pressure distribution in the die caves and uniform velocity distribution on the outlets were obtained, the increase of radius in certain range could decrease pressure drop dramatically, while had little influence on the uniformity of outlet's velocity and stagnation zone.The wall slip is inevitable when the melt flows in the die, the influence of slip condition on the coat-hanger die was studied in this paper by changing slip factor in the Navier slip law. The results show that the smaller the slip factor, the lower pressure drop, but the velocity uniformity on the outlet getting worse. The slip condition has great influence on the pressure and velocity field, so it is not ignorable factor when designing. According to the runner analysis of failed ABS extrusion die from a chemical company, the main cause was found and improvement programs were put forward.The study of influence of manifold entrance radius and slip condition provided a reference for the coat-hanger die design and improvement, which has much practical significance.