Construction of theoretical models for the lifting mechanism of the foundry crane

Abstract

In the lifting drive of the foundry crane, there are emergency situations provoked by failures of bolted connections in the insert of the split drum. The latter is explained by the appearance of unequal gaps in the gearboxes of the «left» and «right» electromechanical systems driven by asynchronous motors with short-circuited rotors powered by individual frequency converters. With high rigidity of the mechanical characteristics of the engines, small deviations in nominal slides can cause a significant variation in engine loads and, as a result, unequal loading of gearboxes and a skew in the loading of the insert. This leads to a violation of the stability of the speed regime of both parts of the drum and to the appearance of additional dynamic loads in the lifting ropes and vibrations of the bucket with metal. The proposed design schemes of the lifting mechanism of the foundry crane allow tracing the nature of simplifications and focusing on possible emergency situations. Lifting models of electromechanical systems make it possible to study their dynamics in typical operating modes. The presence of a gap in the insert when one of the motors is switched off leads to an oscillatory process in electromechanical systems; this especially affects the movement of the insert elements — there are areas of gap opening, which leads to additional dynamic loads in bolted connections and their premature failure. It is recommended to take the elastic moment in the insert as a diagnostic value, by the nature of the change of which it is possible to judge the development of an emergency situation in electromechanical lifting systems.