微注塑成型中对流换热系数对熔体充模流动的影响

Study on Effects of Heat Transfer Coefficient Between Polymer and Mold on Melt Filling Flow in Micro Injection Molding

在熔体流动理论的基础上,通过分析熔体的对流传热机理,并引入对流换热系数模型,对微注塑成型中对流换热系数对熔体充模流动进行了研究。在正方形截面分别为500μm、300μm和200μm的三种长方形微流道中,数值模拟了熔体充模流动,通过与已有实验数据相比较,验证了对流换热系数模型的合理性,并分析了不同的模具温度和熔体温度下,采用常数对流换热系数和对流换热系数模型得到的熔体温度分布及其随微流道特征尺度变化规律。

On base of the theory of polymeric melt filling flow in micro injection molding, the mechanism of convectional heat transfer for polymeric melt was discussed, and the effects of convectional heat transfer on the melt filling flow in micro injection molding were investigated with considering the model of convectional heat transfer coefficient. The three-dimension filling behavior of polymeric melt in rectangle mieroehannels with side length of square section of 500μm, 300 μm and 200μm were numerically simulated, respectively. Compared with existing experiment data, the rationality of the model was proved. On conditions of different mold temperatures and inlet temperatures, the distributions of melt temperature with constant convectional heat transfer coefficient and the model of convectional heat transfer were shown. In addition, the change patterns of meh temperature dependent of the characteristics dimension of the microchannels were studied.