Simulation and control of high-order flatness defect in rolling wide titanium strip with 20-high mill

In the wide titanium strip cold rolling process, the high-order flatness defect is one of the most difficult problems to be solved. Based on the finite element method, considering the anisotropic mechanical characteristics of titanium, an implicit integration calculation model of rolls-strip for 20-high mill was developed, which can simulate the dynamic rolling process. The model was used to analyze the adjustment characteristics of high-order flatness on the 20-high mill. The simulation revealed as the increasing of the 1# and 7# AS-U or 2# and 6# AS-U reduction adjustment, the high-order flatness defect was more aggravated; and as the increase of 3# and 5# AS-U or 4# AS-U reduction adjustment, the high-order flatness defect was alleviated to some extent. In addition, the high-order flatness cannot be effectively adjusted by roll shifting. Finally, the industrial test showed that increasing 4# AS-U reduction adjustment can effectively relieve the high-order flatness defect. After 6 months of strategy test, the high-order flatness defect rate decreased by 33.47%.