Abstract: A method for predicting destruction of a bearing preliminarily finds frequency range of acoustic emission signals indicating fatigue of bearings. In order to find the fatigue-related frequency range, frequency components of electrical noise, mechanical noise, acoustic emissions (AE) due to slip of a bearing, and AE due to plastic-deformation of the bearing are respectively obtained under corresponding conditions, using a test equipment. Then, under a certain condition, combined AE signals of electrical noise, mechanical noise, slip-related AE, plastic-deformation-related AE and rolling-fatigue-related AE are generated. By subtracting the frequency components of electrical noise, mechanical noise, slip-related AE, plastic-deformation-related AE from frequency components of the combined AE signals, the fatigue-related frequency range is obtained. This frequency range is used to predict destruction of a bearing.

Abstract: Method for predicting destruction of a rolling bearing using an apparatus which has a sensor for detecting acoustic emission signals from a rolling bearing, a plurality of band-pass filters which have different specific frequency pass bands within the range of 150-400 KHz, first comparators for comparing outputs from the band-pass filters with their respective reference values for the specific frequency bands, time-measuring devices for measuring time during which the outputs from the band-pass filters exceed the reference values, and second comparators for comparing the time measured with a further reference value. Of all signals detected by the sensor, only those that have frequencies of 150-400 KHz pass the corresponding band-pass filters, and then are compared with their respective reference values. The first comparators signal to the time-measuring devices when the outputs from the band-pass filters exceed the reference values.

Abstract: An apparatus for detecting a failure in a bearing has an acoustic emission sensor which detects acoustic emission from the bearing and outputs signals indicative of power of the acoustic emission, a bandpass filter which passes only signals in the range of from 100 kHz to 500 kHz out of the signals received from the aforementioned sensor, and a comparator which compares each of the signals in the range of from 100 kHz to 500 kHz extracted by the bandpass filter with a predetermined threshold value and outputs event signals each of which expresses that the signal from the bandpass filter exceeds the threshold value. This apparatus also has a computer which receives the event signals from the comparator, determines time intervals in which the event signals occur, totals the number of event signals for respective timer intervals, and determines whether or not the number of totaled events exceeds a predetermined threshold value to determine a failure in the bearing.