Strip Flatness Mechanism Analysis in Single-Stand Cold Mills

Manufacturing high-strength and light-weight (thin gauge) sheet metals presents challenges in the cold rolling processes. Primary reasons are the difficult-to-predict effectiveness of the various flatness control mechanisms, and the associated evolution of roll stress amplitudes. The purpose of this paper is to demonstrate simulations that provide insights into the behavior of various sheet flatness control mechanisms, including roll bending and roll shifting on 4-high and 6-high single stand mills. An efficient, static mathematic model is utilized to analyze mill deflections, strip thickness profiles, and roll stresses. While appropriate roll ‘sizing’ is crucial in designing mills to be competitive for intended products, this requires practical insights into flatness mechanism behavior and peak roll stress characteristics. The knowledge gained from the simulations in this work can assist in interpreting results of automated computational sizing optimization models. Further, it may provide better understanding of general mill deflection behaviors, and help identify interesting situations such as when the peak stress location changes, or wedge type strip thickness profile effects are induced incidentally by specific flatness control mechanisms.