气体辅助注射成型气体穿透界面计算模型研究

气体辅助注射成型由于其显著的优越性得到了迅速地推广应用,对气辅成型过程的计算机模拟成为当前研究的热点课题。针对气辅成型充填模拟的关键问题－气体穿透界面的求解,首次提出了采用匹配渐近展开法求解气体穿透厚度的计算模型,初步的模拟计算获得了与实验一致的结果。

A STUDY ON GAS INTERFACE-PENETRATING SOLUTION OF GAS-ASSISTED INJECTION MOLDING

Gas-assisted injection molding has become mole popular because of its notable ad-vantages. This process comprises a partial injection of polymer melt into a mold cavity, followedby an injection of compressed gas into the polymer melt. The gas penetrates in the polymer meltand forces the polymer melt to fill the whole mold cavity. Because the influence of gas pene-tration considenably complicates melt flows, so the experience of conventional injection moldingis not suitable any more and computer simulation of the process is urgently needed. Computersimulation of this process has become current hot research topic.The solution of gas interface penetration is the principal problem in the implementation of thesimulation. In this paper, the gas penetration interface is described by gas penetration thicknessratio. When governing equations and boundary conditions are made dimensionless, dimensionlesspressure is defined as the ratio of melts pressure and surface tension on unit length interface.Therefore, Capillary Number Ca is introduced into the dimensionless governing equations andboundary conditions. And then a matching asymptotic expansion method is applied to solve theseequations. Ca and Ca2/3 are used as perturbation parameters to get the inner solution and outersolution of gas penetration interface respectively. By matching these two solutions, gas penetrationthickness ratio can be obtained. The result shows that gas penetration thickness ratio is a functionof Ca. This means that gas penetration extent is determined by the balance of surface tension andviscous force on the gas penetration interface.Finally, a comparison between the experimental and simulation results is made, indicating thatthe simulation results seem to agree well with the experimental results and hence proves that abovemathematical model and solving method are correct.