Modelling of bead filling process in lost foam casting based on gas-solid two-phase fluid simulation

摘要

Lost foam casting (LFC), the new generation of precision casting process, is called to be the representation of advanced casting technology. In the LFC, the foam pattern is the key qualification, and the bead filling process is quite crucial to ensure the high quality of the foam pattern. Filling without uniformity and denseness will cause various defects and affect the quality of the casting, Numerical simulation of the bead filling process is carried out to optimise the process, enhance the efficiency and decrease the waster. Based on molecular dynamics simulation, the discrete element method is established to analyse the flow of discrete particles. A universal programme of simulating the LFC bead filling process is developed, which can forecast the movement law and character of foam beads in the die cavity. By comparing the results of visual experiments with simulation results, the rationality of such physics concept and the correctness of the computational method can be tested. Furthermore, the force distribution on the beads and the movement mechanism of the filling process can be analysed at the same time. Factors that may influence the filling process, including the position of the bead inlets, the amount and position of outlets, the initial pressure of the gas phase, etc., are studied respectively.