Strand withdrawal rate stabilization: via the electric drive of the secondary cooling zone of a continuous casting machine

Abstract

Statement of the problem: stabilization of the rate of strand withdrawal out of the mould and the secondary cooling zone after change operations of a tundish or a submerged nozzle is one of the attempts to increase the productivity of a continuous casting machine and the quality of a casting strand. The aim of this work is to study the causes of oscillation occurrence in the rate of strand withdrawal and the development of the electric drive control system of the secondary cooling zone providing the increased machine productivity via stabilization of the rate at preserving the required quality of the internal structure of cast strands. Experimental studies were based on the analysis of the changes in load currents of withdrawal roll motors, the total current of the electric drive of the secondary cooling zone of continuous casting machines, macro template laboratory data on the main internal defects detected in strands with the use of methods of statistical data processing. The result: the method proposed for stabilization of the rate of strand withdrawal by means of compensating the harmonic component of the total moment of resistance of strand withdrawal by the reduced amplitude of oscillations of the strand withdrawal rate more than three times allows improving the quality of the macrostructure of cast strands with the increased strand withdrawal rate by 5 %. The results of mathematical modeling and experimental studies can be used in the design of automated electric drives of the secondary cooling zone of continuous casting machines of curved type.