粉末注射成形充模过程中凝固层形成规律的计算与分析

FORMATION OF SOLIDIFIED LAYER IN DIE DURING FEEDSTOCK FILLING PROCESS IN PIM

根据连续性、动量和能量守恒方程以及固／液界面上能量平衡原理，建立了考虑凝固层后的一维流动模型。采用有限差分法，计算了模腔内壁上注射料凝固层厚度与工艺参数的关系，研究结果表明：模具入口附近凝固层厚度开始急剧增加，然后增加速率逐渐减缓；熔体体积流率越大，凝固层厚度越小；适当提高模具温度，可以减小凝固层厚度，有利于充模过程。

Basing on the equations of continuity, momentum balance, energy balance and engergy balance at the solidmelt interface, a mathematical model of mold filling process with solidified layer forming on the inside mold surface was estabilished by finite difference method. Variations of the thickness of the solidified layer as a function of time, volumetric flow rate and mold temperature was presented. The simulation results show that the initial thickness of solidified layer near the gate increases quickly, while it's accumulated rate decreases slowly. the greater volumeric flow rate, the thinner thickness of solidified layer. It is favorable to filling process if the mould temperature rises properly,which decreases the solidified layer thickness.