Time：2021.01.14 Source：Roller Bearings Suppliers
The causes of rolling bearing noise are more complicated. One is the uneven surface of the inner and outer rings of the bearing, which causes bearing noise. Or, due to the uneven ball diameter, friction with the inner and outer rings causes bearing noise. It is also willing to produce bearing noise due to improper installation and uneven force. According to size and running speed, rolling bearings have their own unique sound. If you can distinguish the causes of the following sound, it will be of great help to judge bearing damage in advance.
First, roll sound channel
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 for the single row deep groove ball bearing under radial load, which has the following characteristics:
· Random noise and vibration;
· Vibration frequency above 1KHz;
· 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;
· When radial clearance increases, sound pressure level increases sharply;
· 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;
· The higher the lubricant viscosity, the lower the sound pressure level, but for grease lubrication, the viscosity, the shape and size of the soap fiber can affect the noise value.
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. Need WSBC 21319 E, click here to learn more.
Second, falling body rolling sound
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, a load of the roller and inner raceway do not 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 features:
· Easy to produce when grease is lubricated, not easy to produce when oil is lubricated. It is more likely to occur when inferior grease is used.
· Often occurs in winter.
· It is also easy to be generated when an only radial load is applied and radial clearance is large.
· It can also be produced in a certain range and the speed range of bearings of different sizes is also different.
· May be continuous or staccato.
· The forced vibration usually excites the second-order and third-order bending natural vibration of the outer ring, thus generating 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.
Third, the shrill sound
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 bearing life and grease life, and it does not affect rotation, but the unpleasant sound is disturbing, especially for large short cylindrical roller bearings bearing radial load. The noise is characterized as:
· Easy to be produced when the radial clearance of the bearing is large.
· Usually occurs in grease lubrication, oil lubrication is less common.
· Decrease as the bearing size increases, and often occurs within a certain speed range.
· Often in winter.
· 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.
Fourth, cage sound
The free vibration of the cage and its impact on the rolling body or the ring during the rotation of the bearing will produce this noise. It may appear in all kinds of bearings, but its sound pressure level is not too high and it is low frequency. It is characterized by:
· Stamped cages and plastic cages can be produced.
· Both thin oil and grease lubrication will occur.
· It is most likely to occur when the outer ring bears the bending moment.
· Easy to appear when radial clearance is large.
Because e the gap between cage pocket and cage and ring inevitably exists in the finished bearing, it is very difficult to eliminate the sound of the cage completely, but it can be improved by reducing the assembly error, optimizing the reasonable gap and cage movement.
Another special sound of the cage is the noise caused by the self-excited vibration of the cage caused by the friction between the cage and the guide surface of other bearing parts. The stamping cage of a deep groove ball bearing is thin, the bending stiffness in radial and the axial plane is low, and the overall stability is poor. When the bearing rotates at high speed, it will produce self-excited vibration due to bending deformation, causing a "buzzing sound".
When bearing under radial load and oil under the condition of poor performance, will hear a "Kacha, Kacha" in the early years of the operation noise, this is mainly due to the rolling element load area after you leave, rolling body acceleration and collided with cage and noise, the crash but as the inevitable operation after a period of time will disappear. Click here to learn more about WSBC 22208 E.
Fifth, the rolling body through the vibration
When bearing under the effect of radial load, it's internal only several rolling element load-bearing, due to the elastic contact with a ring of "spring" of supporting roller in periodic vibration produced by radial load line, the rotation center so move the vertical or horizontal direction, at the same time cause noise. This type of vibration is called a rolling body by vibrating, especially at low speeds.
The amplitude is related to bearing type, radial load, radial clearance and a number of rollers. Usually, the amplitude is small, and the harm will be formed when the amplitude is large. Therefore, the radial clearance is often reduced or appropriate preload is applied to reduce it.
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