气辅挤出口模中滑移段长度对挤出胀大比的影响研究  

Slip Length of Gas-Assisted Extrusion Die Influence on Die Swell Ratio

作　　者：肖建华[1] 柳和生[1] 黄兴元[1] 

机构地区：[1]南昌大学机电工程学院,江西南昌330031

出　　处：《塑料》2009年第1期115-117,共3页Plastics

基　　金：国家自然科学基金项目(20664002;50273012);2007年度教育部科学技术研究重点项目;江西省自然科学基金(0620033);2006江西省教育厅科技项目

摘　　要：采用壁面滑移方程和Thompson变换,对黏弹性高分子熔体在不同气体辅助挤出口模内的流动进行了数值模拟研究。考察了剪切速率、松弛时间和滑移段长度对挤出物挤出胀大比的影响。研究表明:随着剪切速率和松弛时间的增大,挤出胀大比增大;同时发现当剪切速率或松弛时间增大到某一数值时,挤出物出现先收缩后胀大现象,并伴有熔体破裂现象。模拟还表明:延长气辅挤出口模中滑移段的长度可以避免挤出物发生熔体破裂,并可有效降低挤出胀大比。Based on the generalized navier＇ s slip equation and thompson transformation, a numerical simulation system describing the flowing visco-elastic polymer passing through different gas-assisted extrusion （GAE） dies was established. The effects of shear rate, relaxation time and slip length on die swell ratio were investigated by using simulation. The result demonstrated that the die swell ratio was increased with the shear rate and relaxation time. Meanwhile it was found that the extrudate would change from constraction to swelling at a certain value of the shear rate or relaxation time. The simulation also indicated that prolonging the slip length of GAE could avoid melt fracture and reduce the die swell ratio.

关 键 词：气辅挤出 滑移段长度 挤出胀大比 熔体破裂 数值模拟 

分 类 号：TQ320.663[化学工程—合成树脂塑料工业]