Strip tracking measurement and control in hot strip rolling

Abstract

Poor strip tracking is one of the notorious problems threatening process stability in a hot strip mill. These issues often lead to tail pinching and in the worst cases even to cobbles. The main pillars of the strategy set out to tackle these issues for the Hot Strip Mills in IJmuiden are rougher mill camber control and finishing mill strip steering and tail control. For such applications, a camera based measurement system has been developed in-house that is simple, cost-effective and yet both accurate and robust. Moreover, as we show in this paper, the system has proven its merits both as a finishing mill interstand centerline deviation measurement as well as a rougher mill camber measurement. In the latter application the measurement data can be used for automatic levelling in the rougher mill. The results of production tests presented in this paper demonstrate that the camber measurement in combination with a basic rougher mill tilt set-up model is sufficient to reduce the transfer bar camber significantly.