Noise of Rolling Bearings

When the vibration of the rolling bearing propagates to the radiation surface, the vibration energy is converted into a pressure wave and then propagated through the air medium, which the acoustic radiation of the 20-20000Hz part can be received by the human ear. This part is the bearing noise, so the vibration of the rolling bearing is the wave source of noise. Different bearing noise comes from different types of bearing vibration. Noise such as raceway sound is inherent in bearings and an inevitable basic characteristic of bearing operation, often referred to as basic noise.

1. Racetrack sound

The sound of the raceway is caused by the rolling body rolling in the raceway when the bearing rotates, which stimulates a smooth and continuous noise. It only attracts people's attention when its sound pressure level or tone is extremely large. In fact, the sound energy stimulated by the raceway sound is limited. For example, under normal circumstances, the high-quality 6203 bearing raceway sound is 25~27dB. This kind of noise is most typical of single-row deep groove ball bearings bearings bearings bearing radial loads. It has the following characteristics: noise and vibration are random, the vibration frequency is above 1kHz: no matter how the speed changes, the main frequency of the noise is almost unchanged, and the sound pressure level increases with the increase of the speed, when the radial free space increases, the sound pressure level increases sharply. Add: The rigidity of the bearing housing increases, and the lower the total sound pressure level. Even if the rotation speed increases, the non-total sound pressure level does not increase much, the higher the viscosity of the lubricant, the lower the sound pressure stage. However, for grease lubrication, its viscosity and the shape and size of soap fiber can affect the noise value. The sound of the raceway is generated by the inherent vibration of the sleeve after being loaded. Because the elastic contact between the ring and the rolling body constitutes a nonlinear vibration system, when the lubrication or machining accuracy is not high, the inherent vibration related to this elastic feature will be excited, and it will become noise when transmitted to the air. As we all know, even if bearing parts are processed with the highest manufacturing technology in modern times, there will always be minor geometric errors on their working surfaces of varying degrees, resulting in small fluctuations between the raceway and the rolling body to stimulate vibration systems. Although it is inevitable, high-precision processing of part worksheets can be adopted, correctly select bearings and accurately use bearings to reduce noise and vibration.

2. Fallen scrolling sound

Under normal circumstances, most of the noise occurs in large bearings with low speeds and bearing radial loads. When the bearing runs under a radial load, the bearing exists in the load area and the non-load area. If the bearing has a certain radial gap, the rolling body in the non-load area does not contact the inner raceway, but it may contact the outer ring due to the action of centrifugal force. Therefore, at a low speed, when the centrifugal force is less than the weight of the rolling body, the rolling experience will fall and collide with the inner raceway or cage to excite the inherent vibration and noise of the bearing, and has the following characteristics: grease lubrication is easy to occur, oil lubrication is not easy to produce, and it is easier to produce when using inferior grease, it often occurs in winter, for It is also easy to occur when only the radial load is applied and the radial clearance is large, bearings of different sizes are also generated within a specific range and have different velocity ranges, it may be continuous or intermittent sound, the forced vibration often excites the second and third bending inherent vibrations of the outer ring, thus emitring the noise. By using the preload method to effectively reduce the noise and reduce the radial clearance of bearings after installation, the selection of good lubricants can also be improved. Some foreign enterprises adopt light rolling bodies (such as ceramic rollers or hollow rollers) and other technical measures to prevent the generation of such noise.

3. Shrill sound

It is a rather violent scream caused by sliding friction between metals. Although the temperature of the bearing does not rise at this time, it does not have much impact on the bearing life and grease life, nor does it affect rotation, the unpleasant sound is disturbing, especially for large short-cylindrical roller bearings bearings with radial loads, which are characterized by: Bearings are easy to produce when the radial clearance is large, it usually occurs in grease lubrication, while oil lubrication is rare, it decreases as the size of the bearing increases. It often appears within a certain speed range, it often occurs in winter, its occurrence is irregular and unpredictable, and is related to the amount of fat filling, its performance, installation and operation conditions. This kind of noise can be prevented by reducing the radial clearance of bearings and adopting a shallow outer ring raceway structure.

4. Cage sound

During the rotation of the bearing, the free vibration of the cage and the noise caused by its collision with the rolling body or ring. Its sound pressure level is not too high and the frequency is low. Its characteristics are: stamping cavage and plastic cavage can be produced, both thin oil and grease lubrication will appear, when the outer ring withstands bending moments, it is most likely to occur, and when the radial gap is large, it is easy to occur. Another special sound of the cages is the roar caused by the friction between the cages and the guide surfaces of other bearing parts, which triggers the self-excited vibration of the cages. The stamping cage of deep groove ball bearings is thinner, and the bending style in the radial and axial planes is low and the body stability is poor. When the bearing rotates at high speed, it will produce self-excited vibration due to bending deformation, causing a "buzz". When the bearing is under radial load and has poor grease performance, the noise of "clicking, clicking" will be heard in the early stage of operation, which is mainly due to the noise caused by the sudden acceleration of the rolling body after leaving the load area and collides with the cage. This sharp impact sound is inevitable but will disappear after running for a period of time.

There are several measures to prevent the noise of the cadling as follows.

1. In order to make the rotation movement of the cages stable, the sleeve guidance method should be used as much as possible and attention should be paid to the full lubrication of the guide surface. The structure of the conical roller bearing under high-speed working conditions should be improved, and the L-shaped stamping cages guided by the roller should be changed to the ethyl cages guided by the sleeve.

2. When the shaft is rotated at high speed, the vibration amplitude of the cage with large neutron gap is much larger than that of the cage with a small pocket gap, so it is particularly important to take the value of the pocket gap.

3. Pay attention to reducing radial clearance as much as possible.

4. Improve the manufacturing accuracy of the colding as much as possible and improve the surface quality of the caffolding, which is conducive to reducing the noise caused by collision or friction between the rolling body and the colding frame.

5. Actively adopt advanced cleaning technology to effectively and thoroughly clean spare parts and finished products after sleeves to improve the cleanliness of bearings.

The author of this article is Shaanxi Gainhui Heavy Industries Co., Ltd., which is a professional bearing manufacturer and distributor in China. The company supplies many types of the bearings, such as double direction thrust ball bearings, double row spherical roller bearings, etc. With high quality and competitive bearing products, we sincerely provide services to customers all over the world.

Contact us for more details:

E-mail: emily@gainhui.com

Tel: +86-029-88692376

Mob/WhatsApp: +86-18710850036