The Root Cause And Solution Of High Temperature Of Motor Bearing

Bearing as an important part of the motor, the running speed of the bearing will directly affect the performance of the motor, the running speed is too low to take up the motor, too high will cause the motor to burn out the machine at high temperature, generally speaking, bearing overheating refers to the rolling temperature rise of more than 55℃, sliding bearing temperature rise of more than 40℃.

The root cause and solution of high temperature of motor bearing:

1.the rolling bearing installation is not correct, with the tolerance is too tight or too loose.

The working performance of rolling bearings depends not only on the manufacturing accuracy of the bearing itself, but also on the dimensional accuracy, geometric tolerance and surface roughness of the matching shaft and hole, as well as the selected matching and correct installation. In the general horizontal motor, the assembled rolling bearing only bears the radial stress, but if the inner ring of the bearing is too tight with the shaft, or the outer ring of the bearing is too tight with the end cover, that is, when the positive interference is too large, the bearing clearance after assembly is too small, sometimes even close to zero.

In this way, the rotation is not flexible and heat will be generated during operation. If the bearing inner ring is too loose with the shaft, or the bearing outer ring is too loose with the end cover, the bearing inner ring and the shaft or the bearing outer ring and the end cover rotate relatively, resulting in the bearing friction heating and overheating. In general, the inner diameter tolerance band of the bearing inner ring as a reference part is moved below the zero line in the standard. The combination of the tolerance band of the same shaft and the bearing inner ring is much more important than the combination of the tolerance band and the general reference hole.

2. Improper selection or maintenance of grease, poor quality or deterioration of grease, or mixed with dust and impurities, will cause bearing heating.

Too much or too little grease will also cause bearing heating, because too much grease will cause greater friction between the rotating part of the bearing and the grease, while too little grease will cause dry friction and heating.

Therefore, the amount of grease must be adjusted to be about 1/2 to 2/3 of the volume of the bearing chamber space. Improper or deteriorated grease should be cleaned and replaced with a suitable and clean grease.

3. The axial clearance between the outer bearing cover of the motor and the outer circle of the rolling bearing is too small.

Large and medium-sized motors generally use ball bearings at the non-shaft extension end. The extension end of the shaft adopts roller bearing, so that the rotor can be freely extended when it is heated and expanded. Since ball bearings are used at both ends of the small motor, the outer cover of the bearing and the outer ring of the bearing should have appropriate clearance, otherwise the bearing may be heated due to excessive thermal extension in the axial direction.

When this phenomenon occurs, the front and rear bearing covers should be removed, or a thin paper pad should be added between the bearing cover and the end cover to form sufficient clearance between the outer bearing cover and the bearing outer ring.

4. The end caps or bearing caps on both sides of the motor are not installed correctly.

If the end caps or bearing caps on both sides of the motor are not installed in parallel or the stop block is not tight, the ball will rotate out of the track and generate heat.

The end caps or bearing caps on both sides must be reinstalled flat and secured with evenly rotating bolts.

5.Ball, roller, inner and outer ring, ball frame serious wear or metal peeling.

The bearing should be replaced at this time.

6. Poor connection with the loader. Including: poor coupling assembly, excessive belt tension, load machine axis is different, pulley diameter is too small, bearing distance is too far, axial or radial load is too large, etc.

Correct the wrong connection to avoid bearing bearing abnormal force.

7. The shaft is bent.

At this point, the bearing force of the shaft is no longer a simple radial force, so it will lead to the heating of the bearing.

Try straightening the bent shaft or replacing it with a new one.