The bearing hardened with soft dry oil or antirust paste shall be immersed in 100-200 ℃ hot engine oil, clamp the Hot Oil bearing with pliers, and clean the oil stain on the bearing with a brush. The soft dry oil or antirust paste will melt when heated to 100-200 ℃,
which is easy to wash out from the hole of the bearing. Occasionally, just shake the bearing in the oil for many Hot Oil times. The oil will also flow away from the leak (the roller, bead holder, inner ring and outer ring should also be separated when washing).
Soak the bearing in hot oil for 5-10 minutes, hold the inner ring with one hand and rotate the outer ring with the other hand, and the dry oil or anti rust paste on the bearing will be lost. Then put the bearing into clean fire oil, brush it with a gold brush, wash the oil in the ball and the hole, wash it in gasoline once, take it out and put it on clean paper.
When washing centripetal spherical ball bearings and short cylindrical Hot Oil roller bearings, the ball, bead holder, inner ring and outer ring shall be separated for washing.
Premature aging of rolling bearings will cause equipment shutdown. Combined with the author’s motor maintenance practice, this paper Hot Oil introduces the experience of preventing premature aging of rolling bearings.
The reasons for premature aging of rolling bearings are: too tight fit, poor lubrication, misaligned installation, Hot Oil strong vibration, material fatigue, pollution and corrosion, etc.
1. Too tight fit
When the bearing inner ring is forcibly sleeved into the journal, the light one will produce a severely worn annular Hot Oil track at the bottom of the raceway, and the heavy one will have cracks or peeling on the inner, outer ring and ball of the raceway.
Cause: the clearance between the ball and the slideway is too small, the torque increases, the friction increases, and the working Hot Oil temperature of the bearing is too high, which aggravates the wear and fatigue of the bearing and leads to failure.
Prevention method: restore the radial clearance of the bearing and reduce the interference.
There are two inspection methods for bearing assembly quality:
Visual inspection method: when the bearing is installed in the bearing Hot Oil chamber of the motor end cover and the end cover is rotated by hand, if the bearing rotates freely and flexibly without vibration and shaking up and down, it is regarded as qualified.
Feeler gauge inspection method: assemble the motor end cover with Hot Oil bearing on the base stop, and use a 0.03mm thick feeler gauge to check the radial clearance around the bearing.
If the large clearance position is just above the center (horizontal installation of motor), the assembly is correct and reliable, otherwise, the installation is poor. The position of the end cap shall be properly adjusted and reassembled until it is qualified.
The reason is a serious lack of grease or dry aging of grease. Due to the friction heat generated by the high-speed operation of the motor, the bearing temperature is too high and oxidation discoloration occurs, which is manifested in that the ball, cage, inner ring and Journal of the bearing turn brown or blue.
Prevention method: determine the oil replenishment and oil change time according to the four factors of motor operation time, ambient temperature, load condition and quality of lubricating grease.
In general, the oil shall be replenished once when the motor runs for 6000 ~ 10000h; The oil shall be changed once after 10000 ~ 20000 h operation. The oil change of motors with 2 poles or more shall be 1 / 2 ~ 2 / 3 of the volume of bearing chamber, and high-quality lithium base grease (code ZL-2) shall be used.
3. The installation is not centered
If the installation is not centered, there are not only bead marks on the bearing slide, but also uneven wear marks of the ball and deflection. When checking the radial clearance on both sides of the bearing with a feeler gauge, it will be unequal and the difference is large.
The reason may be that the iron hammer has directly knocked on the outer ring of the bearing; The drive belt is pulled too tight (gear engagement); Make the center lines of the driving wheel and the driven wheel not parallel.
When the deflection is greater than 1 / 1000, the bearing operating temperature will be too high, the slideway and ball will be seriously worn, the rotating shaft will be bent and the pressing surface of the end cover bolt is not perpendicular to the bolt axis.
Correct installation method: use a steel pipe sleeve with smooth and flat end face and almost the same thickness as the inner ring of the bearing to press the bearing at the correct position of the clean journal. The force shall be uniform and not too strong. Then check the allowable runout value of shaft end radial according to different motor speeds.
4. Strong vibration
When the motor core fails, the bearing will vibrate strongly. The reasons are: the iron core is deformed by heating; Motor bearing aging; The bending deformation of the rotating shaft is large; The tightening bolts at the end cover stop are loose due to vibration; Weak foundation causes bearing vibration.
Prevention method: turn the iron core into a small one and soak the surface of silicon steel sheet and the opened gap with silicon organic varnish 1052; Replace new bearings of the same model;
Withdraw the rotor core and straighten the bending part of the rotating shaft; 180 ° symmetry method is adopted; Tighten the end cap stop bolts; Reinforce the foundation and tighten the anchor bolts.