Generation mechanism of unsteady bulging in continuous casting-1 -Development of method for measurement of unsteady bulging in continuous casting-

Abstract

In the continuous casting of steel, mold level fluctuation caused by unsteady bulging of the solidifying shell affects the surface quality of the product and stable operation of the continuous casting process. To clarify this problem, inter-roll bulging and unsteady bulging in experimental casting machines and commercial continuous casting machines have been measured by various methods in a number of studies. In this study, the fluctuation of inter-roll bulging with time in a commercial continuous casting machine was measured by an ultrasonic range finder using a water column. In these measurements, the fluctuation of the segment was also considered. The validity of the measured data was estimated by comparison with the mold level. The results showed that both inter-roll bulging and the mold level fluctuated with the cycle calculated from the roll pitch and casting speed, and the amplitude of the mold level fluctuation converted from the amount of fluctuation of inter-roll bulging corresponded to the actual mold level fluctuation. Therefore, the cycle and absolute amount of inter-roll bulging fluctuation measured in this study were considered reasonable. These results also revealed that the value measured in this study corresponded directly to the fluctuation of inter-roll bulging as such.