Acoustic Analysis Techniques for Navy Gyroscope Ball Bearings

摘要

In an effort to develop a method for the acoustic characterization of gyro bearings (both as components and at various stages of the gyro buildup), a study of one promising method was carried out. Sensitive (and discriminating) acoustic analysis of miniature bearings has usually involved the rigorous application of narrow-band frequency analysis interpreted by means of a sophisticated and involved mathematical model. Such a technique, however rigorous it may be, is too slow and complex for use in a production facility by relatively untrained personnel. Of the several real-time, broad-band frequency-analysis methods available, the high-frequency resonance technique was determined by testing actual NARF reject bearings and new bearings, to have the greatest potential for meeting USN requirements. This technique involves the measurement of high-frequency structural resonances in the fixture. These resonance peaks, excited by damage impacts in the test bearing, occur at frequencies sufficiently high (30-50 KHz) that background noise is very low and a good signal-to-noise ratio is obtained. This method has potential for development into a simple, inexpensive instrument for use in screening bearings and for inspection gyro assemblies.