A study of the entry-region length of circular extrusion dies

摘要

The flow properties of a visco-elastic fluid in the entry region of a circular die in the extrusion processhave been investigated. Using the proposed approach, the μme required for the fully developed flowof a visco-elastic fluid can he predicted. It has been found that the fluid flow will become fullydeveloped when the residence μme t{sub}R is seven μmes the relaxation μmeτ. On the basisof theresults, an equation for calculating the entry-region length of circular dies has been derived, and theentry-region length of two rubber compounds in capillary extrusion has been determined, the resultsshowing that the entry-region length is about 1～2 μmes the die diameter.