Strip end flip during finishing rolling under misalignment conditions of work roll pair

Abstract

Misalignment in the assembly of finishing rolls in the mill stand housing often leads to instability of the strip during finish rolling such as snake motion, side walk and strip end flip. Among these problems, the strip end flip is the most serious one. It often occurs upon steel strip end being released from the roll bite of a previous mill stand and being further fed into the next stand. As a result, it may cause folding of the strip end and/or result in serious damage on the finishing roll surface. This would significantly deteriorate the strip quality and cause serious consequence in production. Due to irregularity of occurrence and difficulty in on-site observation, this phenomenon has been a troublesome issue in finishing rolling. The aim of this work was to analyze the effect of the misalignment of the finishing work rolls on the incidence of strip end flip and to postulate possible mechanisms in interpreting the strip end flip phenomenon under misaligned conditions. By adopting the camber condition from a particular on-site strip end and by assuming different degree of misalignment of work roll pair, the numerical model not only predicted the strip end shape, but also reproduced and visualized the strip end flip. The simulated results showed that the occurrence of strip end flip was primarily due to the collision of the strip end side with the side guide arms and was susceptible to the misaligned conditions of the work roll pair. The numerical model provides an effective tool to systematically explore the possible causes of the strip end flip. With appropriated measures, the occurrence of strip end flip can thus be limited and reduced.