Modelling and reduction of back-up roll wear in cold rolling and temper rolling mills

ended

Performance of Back-Up Rolls (BURs) in flat rolling mills is limited by two factors, namely wear and rolling contact fatigue (work hardening). In practice, BURs often exhibit very inhomogeneous wear rates over their barrel length. Local wear rates and the resulting BUR wear profiles are usually not understood and (thus) not well predicted. The BUR wear profile has, in turn, a large effect on the local Hertzian work roll - BUR contact stress distribution along the BUR barrel length. This crucial parameter for rolling contact fatigue is also unknown and also highly inhomogeneous. Consequently, also the onset of local rolling contact fatigue at the BUR surface is poorly predicted and may in fact differ strongly between consecutive mill campaigns of the same BUR, so that mills struggle to define adequate (= safe and economical) practical maximum BUR campaign length limits. BUR wear is affecting the rolling mills in 4 ways: Rolling process stability (risk of pinching), product quality (strip shape deviations), loss of mill OEE (when unscheduled BUR changes are needed) and costs associated with BUR consumption. In this view, the project aims to: • Develop and validate a physical model that quantitatively describes the evolution of the back-up roll wear profile during a cold rolling or temper rolling campaign; • Develop and validate a second model (coupled to the first model) that quantitatively describes the evolution of back-up roll contact fatigue during a cold rolling or temper rolling campaigns • Utilize these models to: (a) improve strip shape control (avoid pinching and improve product quality). (b) optimize scheduling of back-up roll changes and increase back-up roll campaign length. (c) enhance mill output and reduce operating costs of the rolling mill.