三层共挤成型界面偏移和挤出胀大的影响因素  

Influencing Factors of Interface Offset and Die Swell in Three-Layer Co-extrusion

作　　者：张广冬[1] 王林峰 宋树权[1] Zhang Guangdong;Wang Linfeng;Song Shuquan(School of Mechanical Engineering,Yancheng Institute of Technology,Yancheng 224051,China)

机构地区：[1]盐城工学院机械工程学院,江苏盐城224051

出　　处：《工程塑料应用》2023年第12期86-91,共6页Engineering Plastics Application

摘　　要：共挤成型方法在聚合物加工领域有着广泛的应用,主要用于复合板材、管材、薄膜和异型材的成型。共挤制品层厚的准确性和均匀性对复合材料的性能尤为重要,其主要影响因素包括复合界面偏移和挤出胀大。针对三层板材共挤成型,笔者采用有限元分析软件Polyflow对两种聚合物熔体的等温三层共挤成型进行了数值模拟,其中内层材料为聚乙烯(PE),外层材料均为热塑性聚氨酯弹性体(TPU)。分析了内外层入口流率比(Q_(r))、内外层熔体零剪切黏度比(η_(r))以及流道压缩角对界面偏移和挤出胀大的影响规律。结果表明,在三层共挤成型中,随着Q_(r)的增大,成型段和自由射流段的共挤界面向共挤制品的外侧移动,自由射流段的挤出胀大也随之增大。当Q_(r)为1时,挤出成型后三层熔体的层厚基本相同,此时层厚的均匀性最佳。随着ηr的增大,界面偏移和挤出胀大均随之减小。流道压缩角对自由射流段的界面偏移和挤出胀大的影响较小。由于压缩角的存在,与单材料挤出成型相比,三层共挤模具的成型段长度应相应的增大,以保证复合界面的结合强度。The co-extrusion forming method is extensively employed in polymer processing,such as primarily for shaping composite sheets,pipes,films,and specialized profiles.The precision and uniformity of layer thickness in co-extruded products are crucial for composite material performance,the main influencing factors include composite interface offset and extrusion swell.This study focuses on the finite element analysis of isothermal three-layer co-extrusion using Polyflow software.In this simulation,the material of inner layer is polyethylene(PE),and the material of outer layer is thermoplastic polyurethane elastomer(TPU).Several factors affecting the coextrusion process were analyzed,including the inlet volume flow rate of the inner and outer layers(Q_(r)),zeroshear viscosity ratio of the melt in these layers(η_(r)),and the compression angle of the flow channel.The results show that,the co-extrusion interface of the molding section and the free jet section moves to the outer side of the co-extruded product with the increase of Q_(r)in the three-layer co-extrusion molding,and the extrusion swell of the free jet section also increases.Optimal layer thickness uniformity is achieved when the Q_(r)is 1.Moreover,an increase in theηr between the inner and outer melts leads to a reduction in interface offset and die swell.The flow channel compression angle minimally influences the interface deflection and die swell in the free jet section.However,due to the compression angle,the length of the die land in the three-layer co-extrusion die should be increased compared to single material extrusion.This adjustment ensures the bonding strength of the composite interface.

关 键 词：共挤成型 数值模拟 界面偏移 挤出胀大 压缩角 

分 类 号：TQ320.52[化学工程—合成树脂塑料工业]