Subsection cooling system of hot rolling silicon steel and its industrial application

An online subsection cooling method for hot rolling silicon steel was designed to achieve local adjustment of transverse roll gap. Particularly, it was able to meet the requirements of edge drop of the strip by using the features of online thermal crown. First, after the new subsection spray beam was installed at the exit of mill, the special local cooling rules were analyzed for altering the thermal crown of roll according to rolling process parameters. Meanwhile, the dynamic impact of subsection cooling on the local thermal crown could just be obtained according to the measured data. Obviously, the heat transfer coefficient was determined by different subsection cooling curves under varied rolling conditions. Secondly, the rolling rhythm and variable conditions were important dynamic factors of transient roll temperature in practical rolling process. Therefore, real-time calculation and presetting of the thermal crown were carried out to maximize special requirements of load roll gap on local strip crown. By this new method, the transient temperature and the thermal crown of roll could be quantitatively controlled online. And the practical results showed that the predicted temperature was able to match the measured value by more than 95%. Meanwhile, the adjustable range of thermal crown increased by more than 2.5 times. Finally, the qualification rate of strip edge crown has increased from the original 30% to over 70%.