中文摘要：

针对圆管型气辅挤出工艺，建立模拟分析几何模型，选用PTT黏弹性本构方程，采用Polyflow有限元仿真软件模拟研究不同挤出流量、管径、壁厚及气辅段长度时挤出制品的挤出胀大。结果表明，传统挤出时挤出胀大比随挤出流量的增加而大幅增大，气辅挤出时挤出胀大比随其提高而增长甚微，其值始终接近1，可忽略不计；气辅挤出时挤出胀大比随管径增大而微弱增加，随壁厚增大而微弱减小，且都可得到基本消除；挤出胀大随气辅段长度增长而减小，最终趋于1。

英文摘要：

Through the finite element simulation software Polyflow, building pipe-shape geometric model and selecting the PTT viscoelastic constitutive equations, die swell phenomenon of extruded products aiming at pipe-shape gas-assisted extrusion technology was simulated in different extrusion flow, pipe diameter, wall thickness and gas-assisted length. The results show that the die swell ratio of traditional extrusion increases sharply with the increasing of extrusion flow, while increasing faintly in gas- assisted extrusion, which is closed to l and can be ignored. In gas-assisted extrusion, the die swell increases faintly with the increase of diameter, while the die swell decreases faintly with the increase of wall thickness, and both of them can be basically eliminated. The die swell decreases with the increasing of gas-assisted length, and trends to be 1 at last.