Abstract
This paper describes a new method for automatic detection of slight flaws on the outer race of a ball bearing using two vibration pick-ups. On production lines of mass-produced precision ball bearings, the detection and classification of flaws on the balls and races have been carried out by aural monitoring of vibration signals of the outer ring. Some useful automatic methods based on the analysis of the periodicity of vibration pulses excited by the flaws have been developed as alternatives to aural inspection. However, slight flaws on the outer race are not always detected by those methods because the vibration pick-up is almost completely insensitive to the vibration due to a flaw in a direction perpendicular to the pick-up point. Therefore, we have developed a new method to detect slight flaws on the outer race, regardless of the position of flaws. With this method, slight flaws are detected from the cross spectrum between the squared envelope signals of the vibration signals detected by two vibration pick-ups.
