First, the bearing common fault
The failure phenomenon of rolling bearings generally shows two types. One is that the temperature of the bearing installation part is too high, and the other is that there is noise during the operation of the bearing.
1, the bearing temperature is too high
When the main engine is running, the part where the bearing is installed is allowed to have a certain temperature. When the main body casing is touched by hand, it should be normal to not feel hot, otherwise the bearing temperature is too high.
The bearing temperature is too high. The reasons are: the quality of the lubricating oil does not meet the requirements or deteriorates, the viscosity of the lubricating oil is too high; the assembly of the main engine is too tight (insufficient clearance): the bearing assembly is too tight; the bearing race is too large on the shaft or in the casing; Bearing cage or rolling element is broken.
2, bearing noise
Rolling bearings allow a slight running noise during operation. If the sound is too loud or there is abnormal noise or a crash, the bearing is faulty.
The causes of noise generated by rolling bearings are more complicated. One is the wear of the inner and outer rings of the bearing. This wear destroys the matching relationship between the bearing and the housing, the bearing and the shaft, causing the axis to deviate from the correct position, and the bearing operates abnormally when it is under load. When the bearing is fatigued, the surface metal peels off; it also causes the bearing radial clearance to increase and produces an abnormal sound. In addition, insufficient bearing lubrication, dry friction, and bearing crushing can produce abnormal sounds. After the bearing wears loose, the cage is loose and damaged, and abnormal noise is also generated.
Second, the analysis of the causes of damage to bearings and countermeasures
The bearing cannot be directly observed during operation, but the bearing abnormality can be detected by noise, vibration, temperature, lubricant, and the like. Representative example of bearing damage;
1, crack defects
Some of the notches have cracks. The reasons are as follows: the impact load of the main machine is too large, the interference between the main shaft and the bearing is large; the crack is caused by the large peeling friction; the precision is poor during installation; the use is improper (using a copper hammer, a large foreign matter is stuck) and the friction crack.
Countermeasures: Check the conditions of use. At the same time, set appropriate interference and check the materials, improve the installation and use methods, and check the lubricant to prevent friction cracks.
2. Metal stripping on the raceway surface
The running surface is peeled off. After peeling, it is obviously concave and convex. The reason is that the bearing rolling elements and the inner and outer ring raceways are subjected to periodic pulsating loads, thereby generating cyclically varying contact stresses. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the rolling element or the inner and outer ring race surfaces. If the bearing load is too large, this fatigue will be exacerbated. In addition, the bearing is not properly installed, the shaft is bent, and the raceway is peeled off.
Countermeasures: The conditions of use and the selection of bearings and clearances should be re-examined, and the machining accuracy, installation method, lubricant and lubrication method of the shaft and bearing housing should be checked.
The bearing heats up and discolors, and the burn cannot be rotated. The cause of burns is generally insufficient lubrication, the quality of the lubricant does not meet the requirements or deterioration, and the bearing assembly is too tight. In addition, the clearance is too small and the load is too large (pre-pressure is large) the roller is skewed.
Countermeasure: Select the appropriate clearance (or increase the clearance), check the type of lubricant, ensure the injection amount, check the use conditions, prevent the positioning error, and improve the bearing assembly method.
4, the cage is broken
The rivet is loose or broken and the rolling elements are broken. The reasons are: excessive torque load, insufficient lubrication, frequent fluctuations in speed, large vibration, and the bearing is installed under tilted state, and foreign matter is stuck.
Countermeasure: To find out whether the conditions of use and the lubrication state are suitable, pay attention to the use of the bearing, and study whether the choice of the cage is appropriate and whether the rigidity of the bearing housing is required for load.
The inner or outer diameter surface slips, causing a mirror or discoloration, sometimes getting stuck. The reasons are: insufficient interference at the joint, insufficient tightening of the sleeve, abnormal heating, excessive load on the main engine, etc.
Countermeasure: To re-examine whether the interference is appropriate, check the conditions of use and check the accuracy of the shaft and bearing housing.
6, rust corrosion
The surface is partially or completely rusted, and the rolling elements become rusted in a line. The reasons are: poor storage, improper packaging, insufficient rust inhibitor, water acid solvent, etc., and the bearing is directly taken by hand.
Countermeasures: To prevent rust in storage, re-apply oil-applied packaging on a regular basis, strengthen the sealing performance, check the lubricating oil regularly, and replace the oil quality unqualified or deteriorated in time, and use the bearing correctly.
This article label: elevator bearings common faults and treatment methods