微注塑成型中熔体与壁面间传热系数对充模流动影响的研究

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

基于微注塑成型中熔体充模流动理论,对微尺度下熔体与壁面间的传热系数对熔体充模流动影响进行了研究.在分析两相间传热机理的基础上,讨论了宏观尺度流道和微观尺度流道中传热系数取值对熔体温度分布的影响.在引入传热系数模型的基础上,对正方形截面分别为500μm、300μm和200μm的三种长方形微流道中熔体充模流动进行三维数值模拟.通过与已有实验数据相比较,验证了模型的合理性,并分析了不同的模具温度和熔体温度下,采用常数传热系数和传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 basic of the theory of polymer melt filling flow in micro injection molding, effect of heat transfer between melt and wall on filling flow in microscale is investigated. The mechanism of heat transfer between melt and wall is analyzed and effects of heat transfer coefficient on melt temperature distribution in macroscopical channel and microscopical channel are discussed. In terms of referenced heat transfer model, three- dimension melt filling flow for rectangle microchannels with side length of 500μm. 300μm and 200μm at section respectively are numerically simulated. Compared with existing experiment data, rationality of model is proved. On conditions of different mold temperature and inlet temperature, melt temperature distributions with constant heat transfer and heat transfer model and their change rules with microchannel characteristic size are researched.