注塑模稳态温度场的有限体积法模拟

Steady-State Temperature Field Simulation of Injection Mold Based on Finite Volume Method

对于注塑模具的冷却过程稳态温度场模拟,传统有限体积法(FVM)求解型腔面上等效热流时,节点温度梯度往往基于控制体积内的平均值近似计算,不一定等于边界面上的局部节点温度梯度,且控制体积内各面热流计算相互独立,可能导致控制体积内热量不守恒.为此改进FVM通过将稳态温度场热量守恒作为前提条件,基于节点控制体积的其他面热流量计算型腔面热流,修正了传统FVM.自主开发了C++有限体积法数值模拟程序,分别把传统FVM和改进FVM模拟得到的注塑模稳态温度场与商业软件结果对比,发现传统FVM能够模拟出注塑模具的温度分布情况,但存在较大计算误差;采用改进型腔面等效稳态热流算法后,计算误差显著降低,证明改进后FVM能更加准确地模拟冷却过程的稳态温度场.

For steady-state temperature field simulation during cooling stage of plastic injection molding,when the traditional finite volume method(FVM)is used to solve the equivalent heat flux on the cavity surface,the approximate node temperature gradient is often based on the average value in the control volume,but it may not be equal to the local node temperature gradient on the boundary surface.In addition,the calculation of heat flux on each surface in the control volume is independent,which may lead to the non-conservation of heat energy on the control volume.To this end,the improved FVM is modified by taking the heat conservation of steady-state temperature field as a prerequisite and calculating the heat flow of cavity surface based on the node control volume.A numerical simulation software of C++language based on FVM is developed,which compares the steady-state temperature field of plastic injection molding simulated by the traditional FVM algorithm and the improved FVM algorithm with the results of commercial softwares.The results show that the traditional FVM algorithm can simulate the rough temperature distribution of injection mold,but there is a large calculation error.By improving the equivalent steady-state heat flux calculation method for cavity surface,the calculation error is greatly reduced,which proves that the improved FVM algorithm can predict more accurately the steady-state temperature field in cooling stage.