Vibration analysis of Sendzimir cold rolling mill and bearing fault detection

The presence of several rolls in cluster cold rolling mills makes on-line vibration monitoring and failure analysis difficult. The dynamic behaviour of rolls strongly depends on the rolling pressure in the roll bite. Strip vibration applies a dynamic component on the rolling force acting on the work roll and may excite the resonance of the mill stand. This problem motivates predicting the cluster mill dynamics by using a numerical model. It may help in planning the maintenance operation of rolls and bearings and in reducing the service costs. A complete dynamic analysis of the cluster mill layout has seldom been proposed in the literature. In this article, the authors investigate the dynamic behaviour of a Sendzimir mill. A numerical simulator developed in the Matlab/Simulink environment is used to distinguish the effects of chattering, rolls unbalance, motor dynamic irregularities, and bearing fault. Analytical approaches proposed to compute the dynamic component of the rolling force are used as an input to excite the rolls vibration in the cluster mill simulator. Numerical results are used to interpret some preliminary experimental measures performed on the operating Sendzimir mill. Some goals were achieved. This investigation allowed the distinguishing of the dynamic effects due to the rolls from those related to the motor and bearings fault. Critical parameters used in the numerical model were identified. To complete this study, a fully instrumented cold rolling mill has to be used in order to measure all the dynamic signals required to detect the relevant phenomena that have to be prevented.