Optimal profile and shape control of flat sheet metal using multiple control devices

Recent advances on crown and shape control bring the sheet metal industry into a new era of tighter gauge tolerance and better shape performance. Multiple crown control devices were applied to the mills to enhance control capability, to extend schedule length, and to obtain the optimal mill setup. Given the target interstand crowns, it is easy to calculate control parameters for the mill using a single crown control device. A unique solution is expected, hence no optimal selection. The combination of multiple crown control devices can provide more than one set of set-up parameters to satisfy the required interstand target crowns. Hence the mill can be controlled to minimize undesirable operating conditions, for instance, the usage of maximum or minimum roll bending forces, strip walking due to uneven roll shifting or large pair crossing angle difference. Some special operating cases of dummy and malfunction stands can be resolved thanks to the flexibility and profundity of multiple control devices. This article discusses the optimal crown and shape control for the mill using multiple crown control devices.