The structure of bearings has an impact on vibration and noise

The sound of falling and rolling usually occurs in large bearings that are subjected to radial loads at low speeds. When the bearing operates under radial load, the load zone and non load zone inside the bearing. If the bearing has a certain radial clearance, the rolling elements in the non load zone do not contact the inner raceway, but may contact the outer race due to centrifugal force. At low speeds, when the centrifugal force is less than the weight of the rolling elements, the rolling elements will fall and collide with the inner raceway or cage, exciting the inherent vibration and noise of the bearing.

And it has the following characteristics: it is also prone to occur when only radial loads are applied and the radial clearance is large. Within a specific range, bearings of different sizes also have different speed ranges. It is easy to produce when lubricated with grease, but not easy to produce when lubricated with oil. It is more likely to occur when using inferior lubricating grease. It could be a continuous sound or a intermittent sound. It often occurs in winter.

This forced vibration often excites the second-order and third-order bending natural vibrations of the outer ring, thereby emitting this noise. By using the preloading method, the noise can be effectively reduced, the radial clearance of the bearings after installation can be reduced, and the use of good lubricants can also be improved. Some foreign companies adopt lightweight rolling elements, such as ceramic rollers or hollow rollers, and other technical measures to prevent the generation of this noise. Rolling elements vibrate, and when a bearing operates under radial load, only a few rolling elements inside bear the load. The spring support formed by the elastic contact with the ring causes periodic vibration of the rolling elements when passing through the radial load line. As a result, the center of the shaft moves vertically or horizontally, causing noise. This type of vibration is called rolling element vibration, which is particularly pronounced during low-speed operation. And its amplitude is related to the type of bearing, radial load, radial clearance, and number of rolling elements. Usually, the amplitude is small, and if it is large, it can cause harm. Therefore, reducing the radial clearance or applying appropriate preload is often used to reduce it. The sharp sound is a rather intense scream produced by sliding friction between metals. Although the temperature rise of the bearing is not high at this time, it has little effect on the bearing life and grease life, and does not affect rotation. However, the unpleasant sound is unsettling, especially for large short cylindrical roller bearings that bear radial loads.

The sound of the cage is caused by the free vibration of the cage during the rotation of the bearing and its impact with the rolling elements or rings. It can occur in various types of bearings, but its sound pressure level is not very high and it is low-frequency. Its characteristic is that both thin oil and grease lubrication will occur. Both stamping and plastic retainers can be produced. When the radial clearance is large, it is easy to occur. It is most likely to occur when the outer ring is subjected to bending moment.

Due to the inevitable existence of the clearance between the cage pocket and the clearance between the cage and the ring in the finished bearing product, it is very difficult to completely eliminate the cage sound. However, it can be improved by reducing assembly errors, selecting reasonable clearances and cage runout. Another special sound of the cage is the noise caused by the self-excited vibration of the cage due to the friction between the cage and the guide surfaces of other bearing components. The stamping cage of deep groove ball bearings is relatively thin, and the bending stiffness in the radial and axial planes is low, resulting in poor overall stability. When the bearing rotates at high speed, self-excited vibration will occur due to bending deformation, causing buzzing sound.

When the bearing is subjected to radial load and the grease performance is poor, a clicking noise will be heard during the initial operation. This is mainly due to the sudden acceleration of the rolling elements after leaving the load zone, which collides with the cage and produces noise. This collision sound is inevitable but will disappear after a period of operation. The measures to prevent cage noise are as follows: When the bearing rotates at high speed, the vibration amplitude of the cage for bearings with large clearance is much larger than that for bearings with small clearance, so the value of the clearance is particularly important. In order to ensure stable orbital motion of the cage, it is recommended to use the ring guide method as much as possible and pay attention to providing sufficient lubrication to the guide surface. The structure of the tapered roller bearing under high-speed conditions should be improved by replacing the roller guided L-shaped cage with a ring edge guided Z-shaped cage.

Pay attention to minimizing radial clearance as much as possible. Efforts should be made to improve the manufacturing accuracy and surface quality of the retaining frame, which is beneficial for reducing the noise generated by collisions or friction between the rolling elements and the retaining frame. Actively adopting advanced cleaning techniques to effectively and thoroughly clean spare parts and assembled products, improving the cleanliness of bearings.