Construction of a logical-probabilistic model of casting quality formation for managing technological operations in foundry production

Abstract

The object of the study is the quality of castings manufactured in disposable sand molds. The problem associated with the limitations of existing studies focusing only on individual components in assessing the quality of castings was solved. This imposes restrictions on the use of the results of such studies in the context of quality management of finished castings in industrial production. The hypothesis of the study assumed that it is possible to build a model of casting quality formation, on the basis of which technological operations that form casting defects can be identified, and a choice of control for such technological operations can be made. A procedure for constructing a logical-probabilistic model of quality formation is proposed, in which the output variable is the integral criterion for assessing the quality of castings, and the input variables are the quality indicator of the j-th technological operation. The input and output variables are linked by the logical operation "AND" and can take two values – "0" and "1". Therefore, taking into account the sequence of technological operations that form the quality of finished castings, if the value of the l-th quality indicator of a casting in the j-th technological operation falls outside the tolerance field, taking into account the permissible amount of defects, then the value of the quality indicator of the technological operation is taken to be 0, otherwise 1. Thus, if the quality indicator of the j-th technological operation takes a value of 0, then the integral criterion for assessing the quality of castings is also equal to 0 and a search for control is required to ensure the achievement of the specified requirements for this quality indicator. It is shown that the search for control of the technological operation, during which the casting defect was formed, allowing to ensure the specified requirements for the corresponding quality indicator of the casting, is possible on the basis of the transformation of mathematical models, for example, of the "composition – properties" type, built on the "black box" principle. The considered virtual example for cast iron casting "flanged valve body" allowed to draw a conclusion about the practical applicability of the proposed procedure in foundries of industrial enterprises.