Diagnosis of Heat Leveler by Vibration Signature Monitoring

A heat leveler machine can create valuable economical losses in fault situations. By applying on-line monitoring of the vibration signatures, the machine can be followed continuously and the changes in the process and in condition of the mahcine can be detected immediately. The on-line monitoring consists of the on-line adjustment of drive parameters as well as quality control. Generally several kinds of different sensor types are applied into the system. On-line monitoring of rolling bearings usually includes vibration measurement sensors. A heat leveler operates at differnt speeds and loads and the direction of process can be reversed during run. The reliability of the results of the on-line monitoring can be increased by measuring simultaneously different parameters that influence on the vibration of the machine. This method is called multi-parameter monitoring. This paper focuses on the possibilities of on-line monitoring of the support bearings in a metal slab heat leveler by vibration measurements. The leveler is equipped with vibration sensors of low frequencies as well as high frequency acoustic emission sensors. The main issue is experimenting different kind of signal processing methods and optimal procedures are then programmed to the on-line monitoring computer. The measurements in this study were performed in industrial circumstances, in a steel mill. The test machine was a heat leveler machine in normal industrial usage. A method of varying limit values is presented. For this, acoustic emission and acceleration rms-signals are applied. Values are determined by the forces in the leveling cylinders. Forces correspond to the deformation resistance of the steel plates.