Abstract: Base on the analysis of melt flow characteristics in flow channel in T-type extrusion die, a new structure of flow channel with radius-varying manifold and two different thickness choke zones was proposed in this paper. The radius-varying manifold is beneficial to shorten the melt residence time, while two different thickness choke zones is beneficial to reduce the extrusion pressure. Under the condition of uniform melt exit flow rate across the width direction of the flow channel, the differential equation of demarcation curve between two choke zones was deduced based on rheology and solved by numerical method and fitted in design. Case design was conducted with the method proposed in this paper and compared with flow channel designed with constant radius manifold and choke zone thickness. The results show that the differential equation of demarcation curve is reliable and can be used to guide the design of flow channel in T-type extrusion die. When the flow channel with radius-varying manifold and two different thickness choke zones meets the requirement of the uniformity of melt exit flow rate across the width direction of the flow channel, it can not only shorten the melt residence time , but also decrease the extrusion pressure significantly.

Key words: T-type die, variant radius of manifold, structure of flow channel, demarcation curve, melt exit flow rate, residence time, extrusion pressure