管壁厚度对微挤出成型的影响分析

基于Bird-Carreau黏度模型，运用有限元方法对三维等温微管挤出成型流动模型进行了数值分析，主要研究了管壁厚度对微管挤出成型过程中挤出胀大、速度分布、剪切速率和口模压降等重要指标的影响。结果表明，当熔体入口体积流率相等时，随着管壁厚度的增大，挤出物挤出胀大率和横截面尺寸变化量增大；口模出口端面上熔体的二次流动增强，但挤出速度和剪切速率减小；熔体在口模内的压力降明显下降；适当增加管壁厚度，有利于提高微管挤出质量。

Effect of Wall Thickness on Microtubule-extrusion Molding

Based on the Bird-Carreau viscosity model, a three dimensional isothermal numerical model was established for the microtubule extrusion molding by the finite element method, with the emphasis on the influence of the wall thickness, die swell, velocity distribution, shear rate distribution, pressure drop in the micro extrusion molding. It showed that the swell and deformation of the extrudate increased with increasing wall thickness when the polymer melt flow rate was equal under different wall thickness condition. The melt secondary flow enhanced at the die exit plane, but the extrusion speed, shear rate and pressure drop within the die decreased with increasing wall thickness. It was conducive to improve the product quality if the wall thickness was increased appropriately.