注塑成型冷却过程的数值模拟

采用循环平均假设，忽略模壁温度的周期变化，将模具的传热简化为三维稳态热传导总是，考虑到注射模的结构特点（型腔为狭缝面，冷却孔细长），推导出求解其温度场的边界积分方程；注塑件的传热简化为一维瞬态热传导，给出确定其冷却时间及表面循环平均热流的方法；通过模具及塑件传热的耦合迭代分析，使模具－塑料件界面的温度和热流满足相容条件，最终确定模具型腔的温度分布及塑件的冷却时间。最后通过一个例子说明数值模拟在冷却系统设计中的应用。

NUMERICAL SIMULATION OF COOLING STAGE OF INJECTION MOLDING

An efficient numerical simulation has been developed for heat transfer during the cooling stage of the injection molding process. In the simulation, the fluctuating component of mold wall temperature is considered to be negligibly small and mold heat transfer is reduced as three dimensional static heat conduction; heat transfer within the molded part is treated as transient, one dimensional heat conduction; mold exterior is treated as an infinite adiabatic surface. An modified three dimensional boundary element method is used for solving cyclic averaged temperature of the mold containing complex and thin cavity and circular cooling channels. An analytical series solution of molded part temperature is presented to obtain cooling time and cyclic averaged heat flux. These two analyses are iteratively coupled as to match the temperature and heat flux at the mold part interface. An example was demonstrated to illustrate the usefulness of the simulation developed.