Numerical Simulation Of The Filling Stage Of Injection-compression Molding

Injection-compression molding (ICM) is a high-speed and high automatic manufacturing technique, and can solve internal stress problem effectively. It was widely used in optical lens and CD/VCD/DVD andμclass of accuracy standard product in manufacture area. ICM is the most popular injection molding methods to produce high accurate dimension parts.The optical performance, surface roughness, dimensional accuracy, uniformity of density and cycle time of parts all have relationship with flow information and heat transfer in ICM process. Numerical simulation of ICM is an important approach to predict the state of flow front and to aid to the design of the mold and the setting of processing parameters. It is an important means to increase the quality of product.In this paper, the finite element /finite difference/ control Volume method is used to simulate the filling phase of ICM process. The main work is focused on such aspects as follows:1) According to the characteristics of the ICM process, the thickness of the initial mold cavity will change in compression stage. It is the difference with conventional injection molding. The fundamental model and pressure governing equation and temperature governing equation in non-isothermal are established for the flow of 3D thin wall part.2 ) The finite element / finite difference/ control volume method is employed to realize the numerical simulation of ICM filling phase. In the procedure, the FEM method is used to solve the pressure governing equation, and the FDM method is used to solve the energy equation, and the CV method is used to track moving front. The examples demonstrate that the proposed method is viable and robust on predicting the distribution of pressure. It was found that the compression speed and compression stroke are the two factors affecting the molding pressure most significantly. The conclusions show good coincidence with date report.3) The program for the simulation of the ICM process is exploited, and has been integrated to the CAE software Z-Mold developed by NERC of Zhengzhou university. It can realize the input of the geometrical model and processing parameters, and the display of the analysis result. It can offer the efficient references to the design of the mold and the processing parameters.