In this work, the effects of dynamic mold temperature control (DMTC) on melt pressure, cellular structure, and mechanical properties of microcellular injection molding (MIM)-molded parts are investigated experimentally. It is found that with the increase of the mold temperature, the duration of foaming pressure in the cooling stage increases. Meanwhile, the average cell diameter and cell diameter dispersion increases as well as the cell density decreases in MIM molded parts. The turning point of mold temperature after which the foaming pressure in the cooling stage and the cellular structure in MIM molded parts generate a significant change is around the glass transition temperature of the used plastic material. Under DMTC conditions, with the increase of mold temperature, the tensile strength, flexural strength, and impact strength of MIM molded specimens of single gate without weld line change a little, while the tensile strength, flexural strength of MIM molded specimens of double gates with weld line increase obviously. When the mold temperature increases to 120°C and over, the tensile strength, flexural strength of MIM molded specimens of double gates with weld line reach an equivalent level of specimens of single gate without weld line.

中文翻译：

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动态模具温度控制对微孔注塑件熔体压力、蜂窝结构和机械性能的影响：一项实验研究

在这项工作中，动态模具温度控制 (DMTC) 对微孔注射成型 (MIM) 成型零件的熔体压力、多孔结构和机械性能的影响进行了实验研究。发现随着模具温度的升高，冷却阶段的发泡压力持续时间增加。同时，MIM 成型部件的平均泡孔直径和泡孔直径离散度增加，泡孔密度降低。模具温度的转折点在冷却阶段的发泡压力和 MIM 成型部件中的蜂窝结构产生显着变化后，在所用塑料材料的玻璃化转变温度附近。在 DMTC 条件下，随着模具温度的升高，拉伸强度、弯曲强度、无熔接线单浇口MIM成型试件的冲击强度和冲击强度变化不大，而有熔接线双浇口MIM成型试件的抗拉强度、抗弯强度明显增加。当模具温度升至120°C及以上时，有熔接线双浇口的MIM成型试件的抗拉强度、抗弯强度达到与无熔接线单浇口试件相当的水平。