Tight fit
When the inner ring of the bearing is forcibly inserted into the journal, the lighter will cause a severely worn circular path at the bottom of the raceway, and the heavy one will have cracks or peeling on the inner and outer rings of the slideway and the ball. Reason: The gap between the ball and the slide is too small, the torque is increased, the friction is increased, and the working temperature of the bearing is too high, which causes the bearing wear and fatigue to deteriorate and fail.
Prevention method: Restore the radial clearance of the bearing and reduce the interference.
There are two ways to check the quality of bearing assembly:
Visual inspection method: When the bearing cover of the motor end cover is mounted on the bearing, when the end cover is rotated by hand, if the bearing rotates freely and flexibly, there is no vibration and shaking up and down, which is considered qualified.
The feeler gauge method: assemble the motor end cover with the bearing on the frame seat, and check the radial clearance of the bearing with a 0.03mm thick feeler gauge. If the maximum gap position is just above the center (motor horizontal installation) ), the assembly is correct and reliable, otherwise it is poorly installed. The end cap position should be properly adjusted and reassembled until it is qualified.
2. Poor lubrication
The reason is a serious lack of grease or dryness of the grease. Due to the high-speed running friction of the motor, the bearing temperature is too high and oxidative discoloration, which means that the ball, cage, inner ring and journal of the bearing become brown or blue.
Prevention method: According to the running time of the motor, the ambient temperature, the load condition, the quality of the grease, etc., determine the oil replenishment and oil change time. Under normal circumstances, the motor should be replenished once for 6000~10000h; the oil should be changed once for 10000~20000h, and the oil change of the motor with 2 or more poles is 1/2~2/3 of the bearing chamber volume, and High quality lithium grease (code ZL-2) should be used.
3. Installation is not aligned
If the installation is not centered, not only the bead marks on the bearing slides, but also the unevenness of the ball wear marks, and the deflection is also caused. When the radial clearance on both sides of the bearing is checked by the feeler gauge, the difference is large. The reason may be that the outer ring of the bearing is directly struck with the iron hammer; the belt is pulled too tight (the gear is engaged); the center line of the driving wheel and the driven wheel are not parallel. When the deflection is greater than 1/1000, the bearing running temperature is too high, the slide rail and the ball are seriously worn, the shaft bending and the end cap bolt pressing surface are not perpendicular to the bolt axis.
Proper installation method: Use a steel tube sleeve with a smooth end surface and almost the same thickness as the inner ring of the bearing to press the bearing in the correct position of the clean journal. The force should be even when pressed, not too strong. Then check the allowable yaw value of the radial end of the shaft according to the different speeds of the motor.
4. Strong vibration
When the motor core is faulty, the bearing will vibrate strongly. The reasons are: the iron core is deformed by heat; the motor bearing is aging; the bending deformation of the rotating shaft is large; the end cap tightening bolt is loosened due to vibration; the foundation is not strong and the bearing is vibrated.
Prevention method: the iron car is small, soak the surface of the silicon steel sheet and the gap opened with silicon organic varnish 1052; replace the new bearing of the same type; exit the bending part of the rotor core straightening shaft; adopt 180° symmetry method; tighten the end cover Bolt; reinforcement foundation, tighten anchor bolts.
5. Material fatigue
If the metal material fatigue, the bearing raceway and the irregular surface of the ball surface are mixed in the grease, the working noise will increase, the ball will slide, and the radial clearance of the bearing will increase, and the allowable diameter of the shaft end. Increase the yaw value by 2~3 times. The determinants of bearing fatigue include: motor load, speed, air gap, end cap type, material toughness, grease quality grease loading.
Prevention method: According to the motor operation record, when the light load working current is more than 60% of the rated value, run to 2000~25000h, the medium load working current is 60%~80% of the rated value, run to 15000~20000h, heavy load working current After running from 80% to 100% of the rated value to 10000~15000h, the normal fatigue of the bearing material should be considered and the new bearing of the same type should be replaced.
6. Pollution corrosion
At this time, red, brown spotted corrosion occurs on the surfaces of the raceways and balls, and the working noise is increased as compared with the sound of the new bearing.
The reason is that the assembly site is not clean, such as moisture, acid, alkali and toxic gases; tools and hands are contaminated; poor quality lubrication fingers are used.
Prevention method: The bearing should be kept clean by the environment, tools and equipment; the bearing should be clean thoroughly; replace the high-quality lithium grease.
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