Optimization of technological factors of magneticelectric strengthening

Abstract

In order to determine the optimal values of technological factors for electromagnetic hardening process (EMHP), an experimental study of the process of applying ferromagnetic Fe – 2 % V powder coating on 30ХГС (GOST 4543- 71) steel parts was conducted. The process productivity and coating continuity were selected as the target parameters for the EMHP optimization. By applying the experimental design method, based on 5-factor central composite rotatable uniform plan, we have created stochastic models, expressed in regression functions of the second order. It has been determined that the magnetic induction value in the working gap is the most significant technological factor, affecting both target parameters. With the increasing induction magnitude the process productivity and the coating continuity increase non-linearly until the maximum limit value, which was attributed to the forming of current-conductive chains in the working gap, that have varying electrical conductivity and different directions relative to the lines of magnetic field forces. In order to determine the optimal EMHP mode we have solved the problems of finding maximums for greatest productivity and coating continuity within the constraints of the studied factor range. The discovered EMHP-modes, optimal for each separate parameter, coincide only in the value of the magnetic induction and the discharge density. The optimal values for the other control factors belong to different areas of factor range for different optimization parameters. To determine the EMHP modes, balanced against the both parameters, the problem of multicriteria optimization was solved. The obtained solution reveals that the density of discharge currents produces the biggest impact on the process productivity and the coating continuity within the balanced modes. At the same time the high continuity of the coating is achieved by the supplementing increase of peripheral speed of the processed workpiece, which leads to evener distribution of the intensively supplied mass of the ferromagnetic powder on the treated surface. The recommended technological modes of EMHP have been determined, based on the generalized optimality criteria.