Modeling and optimization of the effect of temperature seams on stress-strain state of spherical metal casting molds

The objective of this theoretical study is to evaluate the effect of annular temperature seams in the inner surface of a spherical metal casting mold on the level of stress-strain state (SSS) in it during crystallization of a steel casting. The specificity of this technological process consists in the geometric shape (sphere) of the casting model, when the crystallizing metal creates significant compressive stresses in the inner surface of the mold (in the first moments), which are enhanced by the mold curvature: the mold inner layer, heating up, tries to increase in volume, but this is prevented not only by the cooler outer layers, but also by curvature of the surface layer itself. Two possible applications of the casting mold are being considered: with and without seams. The problem of optimizing the design parameters of temperature seams (recesses) is formulated. It depends on the magnitude of the normal stresses occurring in the casting mold at the initial stage of the steel casting crystallization. When solving the problem, the equations of the linear theory of elasticity, the equations of thermal conductivity and the proven numerical method are used. The paper presents a numerical scheme and a developed algorithm for solving the problem. Crack resistance was estimated based on the magnitude of normal stresses in a spherical metal mold. The optimal design options (schemes) of a spherical metal casting mold found as a result of solving the test problem depend on location of the temperature seams in the shell mold, the stress values in them under conditions of the min-max objective function and the developed algorithm. The results of solving the problem are presented graphically in the form of plots of stresses and temperatures in the studied area in different sections and periods of cooling of the shell mold and the metal growing crust. The obtained results of resistance of a metal spherical casting mold were analyzed.