The present invention relates to a process for the early detection of damage to machine parts, particularly rolling element bearings, in which process forced vibrations are detected by means of a vibration pickup.
British Patent No. 1,367,773 discloses a process for the early detection of damage to machine parts, particularly rolling element bearings, in which process signals from forced vibrations stemming from the machine are detected by means of a vibration pickup. Peak values of the forced vibrations always occur whenever a flaw in an otherwise undamaged surface rolls over a second undamaged surface. The picked up signals are transmitted to a peak value detector and to a mean value calculator. By means of a divider, the ratio of the output signal of the peak value detector to the output signal of the mean value calculator is formed and transmitted to a display unit. If the ratio exceeds a preselected limit, a signal is activated. Surface defects can be detected by means of this process, as long as they are still low in number and extent. However, in the case of this process, access to previously measured results is necessary to set the limit values of the ratio.
A process of the type mentioned above, in which forced vibrations of the machine are detected at the machine by means of vibration pickups, is known from West German Patent No. 3,245,505. For this purpose, vibration pickups are used to measure a first structure-borne noise parameter in the high-frequency range and a second structure-borne noise parameter in the low-frequency range of the frequency spectrum, and both measured values are compared by means of a comparator. On the basis of the measured values of the first structure-born noise parameter and of the second body-noise parameter, an auto-performance spectrum G.sub.11 or G.sub.22, respectively, is formed for each of these parameters. A cross-performance spectrum G.sub.12 is also formed calculated on the basis of both structure-borne noise parameters. A coherence function is formed from these values and a rise in the coherence function serves as a signal for the early detection of damage. Although this process makes it possible to carry out early detection of damage independent of the previous determinations of reference values, this process is not suitable for estimating the remaining service life of the machine part.