Minimising Skidding ill Cold Rolling

摘要

Control of the roll-gap friction is essential for optimising the cold rolling process. High friction conditions can lead to increased roll forces, resulting in strip thickness variation and poor shape in the cold-rolled products. Low friction conditions can lead to skidding, which occurs when the work roll speed is higher than the strip speed at the exit of the roll-gap. Skidding problems can result in uncontrolled vibrations in the mill stand, leading to strip thickness oscillations and, in extreme cases, to strip breaks at high rolling speeds, giving rise to prolonged unscheduled delays. Typically the rolling speed of the cold mill has to be reduced to alleviate the problems associated with skidding. However, this leads to reduced output from the cold mill and could impact on the overall manufacturing supply-chain for sheet steel production. This paper describes the work completed at the BlueScope Steel Western Port Plant to understand and eliminate the skidding conditions at the cold rolling operations.