Low-Frequency Pulsations of the Melt during the Lost Foam Casting Process: Part 2

摘要

An investigation into mold filling during the lost foam casting process taking into account the appearance of low-frequency pulsations of liquid metal in the mold is carried out on the basis of a mathematical model of the kinetics of mold filling. The pressure in the gas space (GS), where the thermodestruction of expanded polystyrene (EPS) occurs, is calculated with allowance for low-frequency pulsations. It is shown that the stability of the mold depends on the metal feed rate, the vacuum in a flask, the section of a riser, and the gas permeability of the sand and the anti-burning-on coating. Pressure pulsations in the GS begin at its maximum. Then pulsations dampen and their amplitude is higher at a smaller gas permeability of the sand and refractory paint (at high coefficients D). The period of pulsations is commonly 0.3-1.5 s and increases during filling. The calculated dependences satisfactorily coincide with the experimental data.