Time：2021.01.28 Source：Roller Bearings Suppliers
Overview of the motor bearing problems
Whether the motor is flexible or not directly affects the power consumption of electric vehicles. If the motor is not running flexibly, it will consume a lot of power, the motor will be louder, the motor will be hot, and the cruising range will be significantly reduced. Among them, excessive motor bearing clearance is the most common type of motor mechanical failure. Then how do we judge whether there is a problem with the motor bearing. Here we will share some tips for listening and judge the motor bearing problem.
1. The raceway
The raceway sound is a smooth and continuous noise triggered by the rolling body in the raceway when the bearing rotates, which only attracts people's attention when the sound pressure level or the tone is great. In fact, the sound energy excited by the raceway sound is limited. For example, under normal circumstances, the sound of the high-quality 6203 bearing raceway is 25 ~ 27dB. This kind of noise is most typical of the single row deep groove ball bearing under radial load, which has the following characteristics:
A.Noise and vibration have randomness;
B. The vibration frequency is above 1KHz;
C. No matter how the speed changes, the main frequency of the noise is almost unchanged while the sound pressure level increases with the increase of the speed;
D. When radial clearance increases, the sound pressure level increases sharply;
E. As the rigidity of the bearing seat increases, the lower the total sound pressure level is, even if the speed increases, the total sound pressure level will not increase much;
F. The higher the lubricant viscosity, the lower the sound pressure level, but for grease lubrication, the viscosity, shape and size of the soap fiber can affect the noise value. Need WSBC 22228 CA/W33, click here to learn more.
The raceway sound source is due to the inherent vibration of the ring after being loaded. The nonlinear vibration system is formed by the elastic contact between the ring and the rolling body. When the lubrication or processing accuracy is not high, it will stimulate the inherent vibration related to the elastic characteristics, which will become noise when transmitted to the air. As we all know, even if the most advanced modern manufacturing technology is used to process bearing parts, there will always be small geometric errors of different degrees on the working surface, so as to generate small fluctuations between the raceway and the rolling body to stimulate the inherent vibration of the vibration system. Although it is inevitable, can take the high precision machining parts working surface, the correct selection of bearings and precise use of bearings to reduce noise and vibration.
2. Rolling sound of falling bodies
Under normal circumstances, the noise mostly appears in the low speed and bearing the radial load of large bearings. When under radial load-bearing, bearing the load and the load area, if the bearing has a certain radial clearance, the load of the roller and inner raceway is not in contact, but because of the action of centrifugal force may be in contact with the outer ring, therefore, under the low speed, when the centrifugal force is less than the rolling body weight, scrolling experience fall with inner raceway or bearing cage collision and to stimulate the natural vibration and noise, and has the following characteristics:
A.Easy to produce when grease lubrication, oil lubrication is not easy to produce. It is more likely to occur when inferior grease is used;
B. It often happens in winter;
C. It is also easy to produce when a radial load is applied only and radial clearance is large;
D. It will also be produced in a certain range and the speed range of bearings of different sizes is also different;
E. It may be continuous or staccato;
F. The forced vibration usually excites the second-order and third-order bending natural vibration of the outer ring, thus emitting the noise. The preload method can effectively reduce the noise and reduce the radial clearance of the bearing after installation. It can also be improved by selecting a good lubricant. Some foreign enterprises adopt technical measures such as light rolling elements, such as ceramic roller or hollow roller to prevent the noise. Click here to learn more about WSBC 22320 E.
3. Sharp whine
It is the sliding friction between metals that produces quite intense screams. Although the bearing temperature rise is not high at this time, it has little effect on the life of the bearing and the life of the grease, and it does not affect the rotation, but the unpleasant sound is disturbing, especially the large short cylindrical roller bearings bearing radial load often have this noise, which is characterized by:
A.Bearing is easy to produce when the radial clearance is large;
B. Usually occurs in grease lubrication, but oil lubrication is less common;
C. Decreases with the increase of bearing size and often occurs within a certain speed range;
D. Winter occurs frequently;
E. Its appearance is irregular and unpredictable and is related to fat filling and performance, installation and operation conditions. This noise can be prevented by reducing the radial clearance of the bearing and adopting a shallow outer ring raceway structure.
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