Numerical Analysis of Intermediate Roll Shifting-Induced Rigidity Characteristics of UCM Cold Rolling Mill

The present investigation devises a flatness control strategy for a five-stand tandem cold rolling mill. In addition, intermediate roll shifting (IRS)-induced rigidity characteristics of the six-high Universal Crown Control mill (UCM mill) as a key model for the automatic thickness and flatness control systems are established. A three-dimensional elastic-plastic finite element analysis for a strip rolling process is conducted when the UCM mill is subjected to different IRS values. The convergence and precision of the simulation model are verified using experimental data in a five-stand tandem cold rolling line. Through a steady-state rolling analysis of the process, the vertical and transverse rigidity characteristic curves of the roll-stack, reduction strain field of the strip, variation in strip crown, elastic deflection of the rolls, and contact stress field between rolls are extracted. The results show that the IRS obviously changes the deflection curves of the rolls and then causes the variations in the exit thickness and transverse thickness difference of the strip. The nonuniform stress distribution between rolls caused by the increasingly IRS value lead to local stress concentration on the side of the roll. A mechanism for the effect of IRS on the rigidity characteristics of the mill is presented and discussed.