Algorithms for controlling the preparation of molding mixtures

Abstract

The formation of foundry and technological defects in castings is largely influenced by the quality of casting molds, which in most cases is determined by the composition and properties of the molding mixture. To ensure optimal parameters of the molding mixture, automation and optimization of control of technological processes of mixture preparation, algorithms for the functioning of process control systems have been developed. The description of the circuit and methods of control using process control system presented. It was shown that the algorithms provide the calculation of the generalized optimization parameter according to the values of the main physical, mechanical and technological properties of the components of the molding mixture, sequential analysis and search of the optimum by the simplex method of Nelder–Mead with restrictions on several parameters. Subsystems of the process control systems considered, which enable to change quickly the technology according to the criterion of minimum defectiveness. The algorithm for calculating the values of the generalized criterion of the quality of the mixture includes a mathematical model “composition – properties” of the mixture, linking the content of the component of the molding mixture (spent mixture, quartz sand, lignosulfonate, bentonite suspension, water) with the values of physical, mechanical and technological properties (compressive strength in the wet state, rammability, formability, gas permeability, binder content, fluidity, wetness and crumbling). The current values of the quality parameters of the mixture are determined as a result of express analysis in the shop laboratory and by automatic sensors. The proposed algorithm of optimization control of preparation of the molding mixture enables to develop recommendations of technological and organizational nature and to set recipes of the molding mixture that minimize the level of defectiveness of castings. An adapted version of the algorithm has been tested for use in the preparation of various brands of molding and rod mixtures, which indicates its versatility.