Symptoms of rolling bearings
The fault phenomenon of rolling bearings is generally manifested as two types, one is that the temperature of the bearing installation site is too high, and the other is that there is noise in the bearing operation.
1. The bearing temperature is too high
When the machinery is running, the part where the bearing is installed is allowed to have a certain temperature, and when touching the machine shell with your hand, it should be normal not to feel hot, otherwise it indicates that the bearing temperature is too high. The reasons for the bearing temperature is too high: the quality of the lubricating oil does not meet the requirements or deteriorates, and the viscosity of the lubricating oil is too high; over-tight assembly of the mechanism (insufficient clearance); over-tight bearing assembly; The bearing housing ring rotates on the shaft or inside the housing; excessive load; Crushing of bearing cages or rolling elements, etc. 2. Bearing noise
Rolling bearings are allowed to have a slight running noise during operation, and if the noise is too loud or there is an abnormal noise or impact sound, it indicates that the bearing is faulty.
The causes of noise in rolling bearings are complex, one of which 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 housing and the bearing and the shaft is destroyed, resulting in the axis deviating from the correct position, resulting in abnormal noise when the shaft is moving at high speed. When the bearing is fatigued, the surface metal peels 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 sounds. After the bearing is worn loosely, the cage is loose and damaged, which will also cause abnormal noise bearing damage
During the disassembly inspection of rolling bearings, the failure of the bearing and the cause of the damage can be judged according to the damage of the bearing.
1. Metal peeling on the raceway surface The bearing rolling elements and the raceway surfaces of the inner and outer rings are subjected to periodic pulsating loads, resulting in periodically varying contact stresses. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the rolling elements or the working surface of the inner and outer ring raceways. If the bearing is overloaded too much, this fatigue can be exacerbated. In addition, improper bearing mounting and bent shafts can also cause raceway spalling.
Fatigue spalling of bearing raceways can reduce the running accuracy of the shaft, causing vibration and noise in the mechanism.
2. Bearing burns
Burned bearings have tempered colors on their raceways and rolling elements. The causes of burns are generally insufficient lubrication, non-compliance or deterioration of oil quality, and over-tight bearing assembly.
3. Plastic deformation
Uneven pits on the raceway and roller contact surfaces of the bearing indicate plastic deformation of the bearing. The reason for this is that the local stress on the working surface of the bearing exceeds the yield limit of the material under a large static or shock load, which generally occurs on bearings rotating at low speeds.
4. Bearing housing ring crack
The cause of cracks in the bearing housing ring may be that the bearing is too tight, the bearing foreign or inner ring is loose, the bearing is deformed, and the surface processing of the mounting bearing is poor.
5. The cage is shattered
The reasons for this are insufficient lubrication, broken rolling elements, skewed seat rings, etc.
6. The metal of the cage adheres to the rolling elements
Possible causes are rolling elements stuck in the cage or insufficient lubrication.
7. The raceway of the seat ring is severely worn
It may be that a foreign object has fallen into the seat ring, the lubricating oil is insufficient, or the lubricating oil grade is not suitable.
