Synchronous Extraction of Cage and Inner Ring Rotational Frequencies in Aircraft Bearings via Weak Magnetic Fields and Adaptive Ridge Extraction for Cage Slip Monitoring

Abstract

Cage slip in bearings is a key factor contributing to bearing failure and is also a crucial parameter for evaluating bearing health. However, existing methods for detecting cage slip are still inadequate. The cage slip is typically calculated by measuring the difference in rotational frequency between the cage and the inner ring. This article presents an innovative monitoring method that achieves synchronous monitoring of the cage and inner ring frequencies by analyzing the variations in weak magnetic signals caused by remanent magnetism and the geomagnetic field, along with an adaptive ridge extraction algorithm. No additional modifications to the bearings are required. Furthermore, the method is not affected by environmental factors such as oil mist and high temperatures. Furthermore, the proposed adaptive ridge extraction algorithm dynamically balances the peak values and curve smoothness in the time-frequency graph of weak magnetic signals during rotational frequency extraction. It also dynamically adjusts the search bandwidth of the ridge and defines extraction regions to effectively avoid interference between the harmonic frequencies of the rolling elements and the rotational frequency of the inner ring, ensuring reliability of frequency extraction, especially during changes in spindle rotational frequency. This method can also locate bearing faults by analyzing the fault characteristic frequencies in weak magnetic signals. The experimental results have validated the effectiveness of this method, demonstrating its significant contribution to the advancement of aircraft bearing condition monitoring technology.