To judge whether the bearing can be used again, it should be decided after considering the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc.
Check the disassembled bearings during the regular maintenance of the equipment, the operation inspection and the replacement of peripheral parts, so as to judge whether it can be used again or whether the use is good or bad.
First of all, carefully investigate and record the dismantled bearing and its appearance. In order to clarify and investigate the remaining amount of lubricant, after sampling, the bearing should be cleaned well.
Secondly, check the condition of the raceway surface, rolling surface and mating surface, and the wear state of the cage for damage and abnormalities.
Check the results, if the bearing is found to be damaged or abnormal, find out the cause and formulate countermeasures according to the content of the damage section. In addition, the inspection results, if there are the following defects, the bearing can no longer be used, and a new bearing needs to be replaced.
a. There are cracks and debris in any of the inner and outer rings, rolling elements, and cages.
b. Any one of the inner and outer rings and rolling elements is peeled off.
c. The raceway surface, ribs, and rolling elements are obviously stuck.
d. The cage is severely worn or the rivets are loose.
e. The raceway surface and rolling elements are rusted and scratched.
f. There are obvious indentations and marks on the rolling surface and rolling elements.
g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.
h. Severe discoloration due to overheating.
i. The sealing ring and dust cover of the grease-sealed bearing are severely damaged.
Inspection and Troubleshooting During Operation
The inspection items during operation include bearing rolling sound, vibration, temperature, lubrication status, etc. The details are as follows:
The rolling sound of a bearing
Use a sound detector to check the size and sound quality of the rolling sound of the running bearing. Even if the bearing is slightly damaged by peeling off, it will emit abnormal and irregular sounds, which can be distinguished by the sound detector.
Vibration of the second bearing
Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, rust, cracks, wear, etc., will be reflected in the bearing vibration measurement, so the vibration can be measured by using a special bearing vibration measuring device (frequency analyzer, etc.) The size of the abnormality cannot be inferred from the frequency. The measured value differs depending on the service conditions of the bearing or the installation position of the sensor, etc., so it is necessary to analyze and compare the measured value of each machine in advance to determine the judgment standard.
The temperature of the three bearings
The temperature of the bearing can generally be inferred from the temperature outside the bearing chamber. If the temperature of the outer ring of the bearing can be directly measured through the oil hole, it is more appropriate. Usually, the temperature of the bearing rises slowly with the start of operation, and reaches a steady state after 1-2 hours. The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubricating and mounting parts are suitable, the bearing temperature will rise sharply and abnormally high temperature will appear. At this time, the operation must be stopped and necessary preventive measures must be taken. The thermal sensor can be used to monitor the working temperature of the bearing at any time, and when the temperature exceeds the specified value, it can automatically alarm the user or stop to prevent the combustion shaft accident.