Numerical Simulation And Application Of Powder Injection Molding Filling Process

In this paper, the finite element analysis software ANSYS is successfully applied to simulate the filling process of PIM. Fractal and Chaos, Two-phase flow, Boundary layer theory are applied to study PIM process. On some desiderated questions of the filling process of PIM, what we have done is a series of fundamental theoretical studies and numerical simulation analysis.Firstly, based on hydromechanics and thermodynamics, PIM process is reasonably simplified and hypothesized. The filling flow is described by Eulerian representation. Conservation equations of mass, momentum and energy in the filling process are deduced in detail. The rheological character and constitutive equation of the feedstock are analyzed. The mathematical model of PIM is established and extended as the form of Cartesian co-ordinates. Based on the mathematical description of flowing boundary condition and diathermanous initial value condition, the integral expressions of the governing equations are deduced. The finite element characteristic equations of the model are given by Galerkin method. And a conclusion is obtained that whether or not the no slip boundary condition is satisfied by the melt at the wall, it does not affect the deduction and calculation of the finite element equations. The front of the flowing melt is traced by VOF method. The finite element numerical algorithm of the discrete algebraic equations of the model is presented. The rheological equation of the feedstock of PIM is added to the viscous models of ANSYS. The functions of ANSYS are extended and the system is reintegrated. And a module of ANSYS that is special for the simulation of the filling process of PIM has been developed. So ANSYS is successfully applied to simulate the filling process of PIM.Secondly, the filling process of PIM in which the feedstock flows round obstacles is estimated in many cases by the special module of ANSYS. Based on the experimental experience and the hydromechanical theory, the results of simulation are analyzed in detail. The relations between the changes of parameters of PIM process and the forming of defects are discussed. Some optimization methods of parameters in PIM...