Robust methods for controlling casting processes and the quality of castings

Abstract

The paper considers the ways of controlling the processes of producing good-quality castings by using robust methods based on the identification of objects under uncertainty, adaptive control methods, stabilization methods for automatic control systems and their mathematical description. The purpose of the paper is to practically elaborate on the task of creating robust technologies for casting based on the study of the stochastic dispersion models of the casting process parameters and to develop a method for stabilizing the casting processes and a method for stabilizing the quality parameters of the castings. The regular patterns of the stochastic dispersion of the casting process parameters were investigated based on the mechanical performance of the casting alloys, their chemical composition, the physical and mechanical properties of the molding mixtures, the dimensions of the castings, and the features of the casting production process such as pouring temperature, element loss during melting and mold hardness. The results of the conducted investigations have shown that to describe the stochastic dispersion of the casting process parameters, it is appropriate to use the Johnson system of distributions. A method for stabilizing the casting quality parameters was developed. It has been shown that it is more efficient to stabilize the strength and improve the dimensional accuracy of the casting simultaneously. With the existing production process, the dimensional accuracy of the casting corresponds to Grade 11 according to GOST 26645-85. With the increase of the dimensional accuracy grade, the metal content of the casting can be reduced by 16.3% after reaching Grade 10, by 20.4% after reaching Grade 9, and by 24.2% after reaching Grade 8.