Studies on the Vibration and Sound of Defective Rolling Bearings : Second Report : Sound of Ball Bearings with One Defect

An investigation was undertaken with a view to establishing a procedure for diagnosing defects in rolling bearings from their vibration and sound. In the present investigation the sound of a rolling bearing with one dent in the race surface of the inner or outer ring or in the ball surface was studied. When the inner ring was rotated at a constant speed under a given thrust load applied to the outer ring, the sound occurring in three directions, i.e., radial, 45° and frontal was measured by a condenser microphone. Using the output so obtained, sound waveforms were observed, real time frequency analysis of the sound was done using Fast Fourier Transform analyzer, and the microphone position effects on the sound, etc. were examined. As a result, the fundamental characteristics of the sound of ball bearings having one dent were clarified, and a method by which to locate the defect and determine its size was established.