The rolling sound is caused by the rolling of the rolling elements in the raceway when the bearing rotates to excite a smooth and continuous noise, which only attracts people's attention when its sound pressure level or tone is extremely large. In fact, the sound energy stimulated by the rolling track is limited. For example, under normal conditions, the quality of the 6203 bearing raceway is 25 to 27 dB. This type of noise is the most typical of single row deep groove ball bearings that can withstand radial loads. It has the following characteristics: a. noise and vibration are random; b. vibration frequency is above 1 kHz; c. no matter how the speed changes, the noise main frequency Almost constant and the sound pressure level increases with increasing speed; d. When the radial clearance increases, the sound pressure level increases sharply; e. The rigidity of the bearing housing increases, and the lower the total sound pressure level, even if the speed increases The total sound pressure level also increases little; f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.
The source of the rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even with the most advanced manufacturing techniques used to process bearing parts, there are always small geometric errors in the working surface, which causes small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system. Although it is unavoidable, it is possible to use high-precision machining of the working surface of the part, the correct selection of the bearing and the precise use of the bearing to reduce noise and vibration.
2. Falling body
This noise is generally found in large bearings that are subjected to low radial loads and subjected to radial loads. When the bearing is running under radial load, the bearing load zone and the non-load zone are in the bearing. If the bearing has a certain radial clearance, the rolling element in the non-load zone does not contact the inner raceway, but it may be external due to the centrifugal force. Ring contact, for this reason, at low speed, when the centrifugal force is less than the weight of the rolling element, the rolling element will fall and collide with the inner race or cage and stimulate the natural vibration and noise of the bearing, and have the following characteristics: a. Grease lubrication It is easy to produce and is not easy to produce when oil is lubricated. It is more likely to be produced when using inferior grease. b. Winter often occurs. c. It is also easy to produce when only radial load is applied and the radial clearance is large. d. Bearings that are also produced within a certain range and of different sizes have different speed ranges. e. It may be continuous or intermittent. f. The forced vibration often excites the second-order and third-order bending natural vibrations of the outer ring to emit the noise. By using the preload method, the noise can be effectively reduced, and the radial clearance of the bearing after installation can be reduced. The use of a good lubricant can also be improved. Some foreign companies use light rolling elements such as ceramic rollers or hollow rollers. To prevent this noise from being generated.
3. Whistling
It is a squeaking of the metal between the sliding friction, although the temperature rise of the bearing is not high, it has little effect on the bearing life and grease life, and does not affect the rotation, but the unpleasant sound is disturbing, especially Large short cylindrical roller bearings bearing radial loads often have this noise, which is characterized by: a. The bearing radial clearance is easy to produce. b. Usually appears in grease lubrication, oil lubrication is rare. c. As the bearing size increases, it decreases, and often occurs within a certain speed range. d. It often appears in winter. e. Its appearance is irregular, unpredictable, and related to the amount of grease and performance, installation and operation conditions. This noise can be prevented by reducing the radial play of the bearing and using a shallow outer ring raceway structure.
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