| Filling process,as the initial stage of injection molding process, the melt flow state at this stage have greater impact on the final performance and quality of products.Numerical simulation of the filling process predict defects and optimize the process.Hele-Shaw flow theory have achieved good results in simulating thin-walled products, however, it ignores the pressure gradient and velocity components, and therefore it can not simulate the products with complex shape and uneven thickness.According to the characteristics of injection molding, the reasonable simplification and hypothesis were introduced, combined with the finite element method, using VC++ program, and the mathematical model of the filling stage was build, the main work and conclusions are as follows:1.In this paper, applicability of Hele-Shaw approximation is analyzed.With removing the Hele-Shaw approximation from the mathematical model developed in the present thesis, combined with injection molding filling theory, the mathematic mold of section of thickness is built. The velocity and pressure in the filling stage of injection-molded parts are simulated with finite element method. Take uneven thickness section as examples.The simulation results indicate that in thickness direction, Hele-Shaw approximation do not work well in the area where the thickness suddenly changed, and in this area the direction of speed varies, and in the corner of the thick side appears stagnant condition.2.In this paper, Take S as deviation factor to represent the value of the Hele-Shaw approximation error. The simulation results indicate that Hele-Shaw approximation is not reasonable in the area where the thickness suddenly changed, besides, whatever thickness of the products becomes thicker or thinner, the larger deviation appears in the thicker section.3.Based on the basic equation of viscous fluid, combined with Hele-Shaw approximation, the 1D flow mathematical model was build.
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