在分析T型模具中熔体在流道中的流动特点的基础上，提出了采用变歧管半径和不同厚度阻流区（两个）的流道结构，采用变歧管半径以减小熔体的停留时间，采用厚度不同的两个阻流区以降低挤出压力。在满足熔体沿流道宽度方向出口流率均匀的条件下，利用流变学理论推导了两个阻流区分界曲线的微分方程，并采用数值方法对其求解和拟合；然后进行了实例设计，并与歧管半径和阻流区厚度不变的流道进行了对比研究。结果表明：所推导的分界曲线微分方程是可靠的，能够指导T型挤出模具的流道设计；采用变歧管半径和两个不同厚度阻流区的流道在满足熔体出口流率沿流道宽度方向均匀的条件下，既可以显著降低熔体在流道中的停留时间，又能够显著降低模具的挤出压力。

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.