EFFECTS OF ROLL CROSSING ON THE ROLLING PROCESS IN 4 HIGH MILLS

Roll crossing can be utilized as a method for profile and flatness con trol in a rolling mill. The estimation of the profile adjusting range by calculating the elastic roll-gap deflection reveals that roll cross ing has a similar effect on the profile as positive bending. Under the assumptions made in the calculations roll crossing is an effective me thod as profile and crown actuator. Furthermore the effect of roll cro ssing on the flatness is qualitatively confirmed by rolling trials. Be yond the investigation of the effectiveness of roll crossing as profil e and flatness actuator a 3-dimensional finite element simulation of t he material flow in the roll gap was done. The results of these simula tions, which were confirmed by rolling trials as well, showed that the rolled specimen warps out of the passline due to the crossing of the work rolls whereas the influence of roll crossing on the distribution of local plastomechanical values is negligible. Force components in ax ial direction are induced by crossing the rolls, which have to be comp ensated by additional bearings. For the determination of the amount of axial forces rolling trials on a laboratory four-high mill were carri ed out.