The Experiment And Simulationstudy Of Gas Injection Volume Of Microcellular Foam Injection Process

Microcellular foaming technology develops into a new kind of plastic processing technology since the1980s.Microcellular foam injection molding technology, which improves the property of the products and reduces the cost of production, is a new injection molding technology with great development prospect. Mucell microcellular foaming technology, which was first used in the U.S. and Europe, then expanded its application to Japan,Southeast Asia and other regions, is just getting started in China.In microcellular foam injection process, the amount of gas injection has an important influence on product quality. So, it is vital to control the gas injection volumein the microcellular foam injection process. Because the foaming agent is influenced by temperature, pressure, time and some other parameters, so the injection dosage of the foaming agent can be different every time, and strongly affect the product quality of microcellular foaming. The control of the gas injection volume in the microcellular foam injection process is studied in this paper.By using the methods of experiment and simulation, based on the restricted flow gas injection system, the control method and principle of the gas injection volume in the microcellular foam injection system is studied. By analyzing the actual data of the gas injection volume in the microcellular foam injection system and by using modern control theory and data analysis method, the transfer function of the key part in the injection system is established. The theoretical relationship between gas injection volume, gas injection pressure and melt pressure is obtained in a certain process condition.In experiment, the restricted flow gas injection system is used. By fixing the fluid-limiting components and ignoring the influence of temperature, the change rule of gas injection rate and gas injection volume under different gas injection pressure and melt pressure is studied. The specific gas injection rate and gas injection volume under different gas injection pressure and melt pressure are obtained. The effect of different gas injection pressure on melt pressure is discussed.Matlab software is used in the modeling and identification of the microcellular foam injection molding gas injection system. The gas injection volume of the microcellular foam injection molding gas injection system is simulated. And the simulation results are revised by nonlinear data fitting method based on the Matlab least squares method. The difference comparison between simulation results and experimental data is conducted to check and analyze the applicability of the simulation model.At last, by means of experiment and simulation, the formula of gas injection volume, gas injection pressure and melt pressure is obtained. The analysis and comparison between simulation data and experimental data reveals that the established dynamic model is accurate and the simulation data is well matched with the experimental data. It is implied that the model can be used to dynamically describe and predict the change rule of gas injection rate. By using the formula from the simulation, the gas injection volume of the restricted flow gas injection system can be controlled.