【摘要】 基于流体动力学和聚合物流变学等理论建立了三维微管精密挤出流动模型,运用有限元方法进行了数值计算,通过对口模内外熔体各物理场量的分析,研究了定型段长度对微管挤出成型的影响。研究结果表明,口模压降、剪切速率随着定型段长度、熔体流率及熔体黏度的增大而增大;挤出胀大率随着定型段长度和熔体黏度的增大而减小,但受熔体流率的影响不明显。根据研究结果,获得了一定条件下定型段的最佳长度,进行实际口模设计时,若熔体流率或熔体黏度增大,可适当减小定型段长度,但当微管壁厚增大时,应适当增加定型段长度。更多还原

【Abstract】 A three-dimensional precision extrusion model for micro tube was developed based on the theory of fluid dynamics and polymer rheology. The effect of the shaping section length on microtubule-extrusion molding was investigated by analyzing the accurate flowing distribution during melt micro extrusion process. The research results showed that die pressure and shear rate increased with the increasing of shaping length,melt volumetric flow rate and viscosity. The die swell decreased with the increasing of shaping section length and melt viscosity,but the melt flow rate had little influence on die swell.According to the study,the optimum shaping section length was gained under the given conditions,that is,the shaping length should be shortened appropriately if the melt flow rate and viscosity increased and be lengthened if wall thickness increased.更多还原