Predictive Maintenance Of Ball Bearings For Machine Rotating With Arbitrary Velocity Profiles

Recent research and development on servomotor technology and on their control system push forward the application of these devices as electric cams in a large numbers of industrial applications, such as example motion control system for packaging machineries. Performances of these devices are much higher than the mechanical solutions for machine motion, in terms of precision and operational speed, and, of Course, in time required to reconfigure the motion profile. However, classical approaches to the ball bearing diagnosis that use analysis of vibration signals are not longer applicable, as they have been developed on the hypothesis of drive constant speed. In fact, in most of the current industrial application, the control system drives the motor to follow a complex and cyclic (i.e. motor shaft reverses its motion direction at each operational cycle) non constant speed motion profile. In those application, even Computed Order Tracking [I I (COT), which is the main fault bearing diagnosis technique used in non-constant velocity applications, fails to detect incipient faults, as highlighted by Fyfe and Munck In [2]. This paper presents a new procedure that modifies the COT to be Successfully applicable to the diagnosis problem of ball bearings in variable speed motion applications.