ANALYSIS OF STRIP TRACK-OFF DURING FLAT ROLLING

摘要

The effects of various asymmetric conditions on strip tracking in a single cold rolling stand have been analysed using mathematical modelling. The potential direction and the relative intensity of the track-off are identified for several asymmetric conditions. It is shown that all asymmetric conditions considered could lead to a track-off if the turning moment acting on the strip is not counteracted away from the roll bite and if the strip is free to rotate. Since the strip off-center produces the largest turning moment, even a small track-off resulting from other asymmetric rolling conditions would lead to rapidly increasing turning moment and the rate of the track-off for the unconstrained strip. The turning moments generated by various asymmetric scenarios can be completely compensated by application of unequal jack forces or roll forces. They can also be significantly reduced by a simultaneous increase in mean tensions applied to the strip both at the entry and exit. The model can be used as a tool for studying the effect of constraints imposed on the strip by upstream tension producing devices, which is the subject of further study. It is believed that the model can potentially be used in on-line control devices or to design the operating window for stable operation for a given schedule.