微注塑拉伸试样设计及流动特性分析

Design and Flow Characteristic of Micro Injection Molded Tensile Specimen

微拉伸试样的设计,是成功测试微尺度下力学性能的关键。文中设计了不同厚度微拉伸试样及相应的微注塑模具,分析了模具设计及尺度效应对微拉伸试样充填行为的影响,并研究了工艺参数对不同厚度微试样(0.1mm、0.2mm、0.5mm、1mm)充填行为的影响。短射实验表明,随着微试样厚度减小,在微试样有效拉伸长度内,熔体流动前沿呈现为一维平板流动;4个厚度下,0.5mm厚的熔体流动性明显优于其它3个尺寸。工艺影响实验表明,随注射速度、模具温度、熔体温度工艺参数的增加,熔体流动性增强。

Design of micro tensile specimen is the key to determining the tensile properties successfully. Micro tensile samples with different thickness （0. lmm, 0.2mm, 0.5mm, 1mm） were designed, and the corresponding micro injection mold was made. Influence of mold design and scale effect on filling characteristic was investigated, and the influences of process parameters on flow pattern of micro samples with different thickness were also involved. The results of short shot experiments show that the melt front in the gauge length of micro sample gradually displays as 1D flow pattern with the decreasing of the thickness of the sample. The 0.5 mm part shows better flow characteristic than the others. The influence of the process parameters on filling behavior reveals that the melt flowability improves with the increasing of injection Velocity, mold temperature, melt temperature.