Optimisation of work roll shifting and bending to roll thinner gauge HR coils using genetic algorithm

Abstract

Rolling of thin gauge hot rolled (HR) coils demands stringent flatness tolerance. Thin HR coils (≤3 mm) are rolled towards the end of any rolling campaign. The profile and flatness of the strip depend on the profile of the loaded roll gap in the mill stands. There are five key factors that influence the loaded roll gap: initial roll surface profile, roll thermal expansion, wear of roll, deflection of roll stack and shifting of work rolls. This paper deals with all these factors individually for the formulation of an objective function in order to minimise the flatness error. The shifting and bending of rolls are the controllable parameters that require optimising. This has been accomplished using a genetic algorithm (GA) optimisation technique.