Modelling and Control of Pressurized Molten Metal in Press Casting

Abstract

AbstractThis paper presents a modeling and control of molten metal's pressure in a pressing process using an innovative iron casting developed by our group. In this method, molten metal is directly poured into the lower mold, and then pressed to fill the cavity by the upper mold being lowered down. For the complex liquid flow during pressing, the liquid's pressure change inside vertical path with various contraction and expansion geometries is newly modeled via the unstationary Bernoulli equation. The mathematical model is derived for a control design of pressing. To conduct the pressing velocity design algorithm, an unknown parameter of proposed model considering viscous flow is identified by using CFD: Computational Fluid Dynamics model with heat flow calculation. Control performance using a multi-switching velocity pattern is confirmed as an effective control design using the pressure model, because the pressure fluctuation has discontinuous variation points. Substituting detailed information for mold shape, poured volume and initial temperature into a developed control input generator, an optimum pressing velocity design and a robust design for defect-free production are proposed by the design algorithm based on the construction of an inverse system comprised of the sequential switching from higher to lower speed. Consequently, the effectiveness of the pressing control with reasonable pressure suppression has been demonstrated through the CFD simulation.