Analysis of common failure causes of motor bearings

Time：2021.02.22  Source：Roller Bearings Suppliers

Bearing, as one of the important parts of the motor, its performance will directly affect the normal operation of the locomotive. When the bearing is broken, damaged and sintered, it will seriously affect the driving safety of the locomotive. Therefore, the motor bearing is also very important for the locomotive. Let's share some common failure causes of motor bearings.

1. The quality of the bearing itself

The bearing has problems before unpacking and assembly, such as loose cage rivets, cage deformation and bumps, scratches on the rollers or raceways, and even the bearings are rusted. Because the bearings are newly manufactured by random inspection, the individual bearings with these defects are likely to be loaded and used as qualified products. Once loaded and used, the bearing will inevitably give an alarm.

2. Improper assembly leads to bumps on the bearing

When assembling motor bearings, a hydraulic machine is generally used to press the outer ring of the bearing into the bearing chamber. If biased during the press-in process, the outer ring is likely to be deformed and damaged. It is not allowed to install the bearing into the bearing chamber by knocking. When assembling the rollers of the inner ring and outer ring, if there is a deflection, it is easy to produce axial scratches on the roller and raceway surfaces, which will cause an alarm when the bearing is running.

According to the analysis of dismantling and inspection:

(1) There is an equilateral triangle bump on the edge of the raceway surface of the bearing inner ring, which is caused by the bump between the roller and the raceway surface of the inner ring during assembly.

(2) There are obvious circumferential scratches in the bearing inner ring, which is caused by foreign matter entering the bearing.

3. Cleanliness impact

(1) Grease cleanliness

Bearings have high requirements for the cleanliness of grease. If the added lubricating oil is mixed with particles such as quartz sand, iron filings, etc., it will cause permanent damage to the bearing during the operation of the bearing, which will seriously affect the use of the bearing.

(2) Cleanliness of parts

Bearing-related parts include bearing caps, oil guide tubes, end cover bearing chambers, etc. If these parts are not thoroughly cleaned, impurities will be mixed into the bearing during assembly and affect the use of the bearing.

(3) Assembly environment

When the bearing is assembled, the surrounding environment has a lot of dust, which is mixed into the bearing chamber or bearing grease during the bearing assembly process, which will also cause bearing failure

4. Current corrosion

After the bearing is assembled and in use, due to external reasons, an unknown current flows through the bearing, which will cause current burning points on the bearing raceway surface and rollers, which will affect the service life of the bearing. This type of current corrosion is generally nothing more than two types. One is that when the locomotive is completed, the return ground wire overlap position is incorrect during the electric welding construction, which causes the bearing to be energized and causes electric corrosion; the other is that the motor itself generates leakage current or motor After the blasting occurs, electric current flows through the bearing to produce electric corrosion.

5. Use maintenance

When the locomotive was used in the section, it did not receive normal and effective maintenance. Such as failure to carry out regular quantitative refueling, failure to control refueling cleanliness and refueling volume, inconsistent grease type, bearing oil leakage, and other problems that sometimes occur.

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