Generally speaking, the rolling bearing itself does not produce noise. The “bearing noise” usually felt is actually the sound effect of vibration between the bearing and the surrounding structure directly or indirectly. This is why many times noise problems can be regarded as vibration problems involving the whole bearing application.
(1) Excitation caused by the change of the number of loaded rolling elements: when a radial load is loaded on a bearing, the number of loaded rolling elements will change slightly during operation, which causes the deviation of the load direction. The resulting vibration is inevitable, but can be reduced by axial preloading, which is applied to all rolling elements (not applicable to cylindrical roller bearings).
(2) Local damage: a small number of bearing raceways and rolling elements may be damaged due to incorrect operation or installation. During operation, rolling over damaged bearing parts will produce specific vibration frequency. Vibration frequency analysis can identify damaged bearing components. This principle has been applied to condition monitoring equipment to detect bearing damage. To calculate the bearing frequency, refer to the calculation program “bearing frequency”.
(3) Accuracy of relevant parts: when the bearing ring is closely matched with the bearing seat or transmission shaft, the bearing ring may be deformed by matching with the shape of adjacent parts. If deformation occurs, vibration may occur during operation.
(4) Pollutants: if operating in a polluted environment, impurities may enter the bearing and be rolled by the rolling element. The vibration degree depends on the quantity, size and composition of the impurity particles being rolled. Although the typical frequency form will not be generated, a disturbing noise can be heard.
The causes of rolling bearing noise are complex. One is the wear of the mating surfaces of the inner and outer rings of the bearing. Due to this wear, the matching relationship between the bearing and the shell and between the bearing and the shaft is damaged, resulting in the axis deviation from the correct position and abnormal noise when the shaft moves at high speed. When the bearing is tired, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal noise. In addition, insufficient bearing lubrication, dry friction and bearing breakage will produce abnormal sound. After the bearing is worn and loose, the cage is loose and damaged, which will also produce abnormal noise.
Post time: Nov-07-2022