Rolling bearings usually do not produce noise themselves. What is considered to be "bearing noise" is actually a sound produced when the structure around the bearing generates vibrations, either directly or indirectly. Therefore, noise problems should generally be considered and resolved in terms of vibration issues that involve the entire bearing application. Vibration and noise are often a concomitant pair of things. The root cause of noise can be attributed to vibration. Therefore, solving the noise problem should start with reducing vibration.
Bearing vibration can basically be attributed to the number of rolling elements in the load changes, with the accuracy, local damage and pollution and other factors to stimulate, should be through the rational allocation of bearings as much as possible to reduce the impact of these factors.
Exciting force factors caused by changes in the number of loaded rolling elements
When the radial load acts on the bearing, the number of rolling elements subjected to the load during the rotation will slightly change, which causes the bearing to have a slight displacement in the direction of the load, and the resulting vibration cannot be avoided, but can be achieved by Axial preload is applied to all rolling elements to reduce vibration (not suitable for cylindrical roller bearings).
Matching component accuracy factors
If there is an interference fit between the bearing ring and the bearing housing or the shaft, the bearing ring may deform following the shape of the coupling part. If there is a difference in shape between the two, it may cause vibration during operation. Therefore, the journal and socket must be machined to the required tolerance standards.
Local damage factor
If the bearing is not properly handled or installed, it may cause local damage to the raceways and rolling elements. When a damaged bearing component has rolling contact with other components, the bearing generates a special vibration frequency. By analyzing these vibration frequencies, it can be determined which bearing component is damaged, such as the inner ring, outer ring, or rolling elements.
Bearings work under contaminated conditions and it is easy to get impurities and particles in. When these contaminated particles are rolled by the rolling elements, vibrations may occur. The different components in the impurity, the number and size of the particles cause different levels of vibration, and there is no fixed frequency pattern. But it can also produce annoying noise.
Influence of bearing on vibration characteristics
In many applications, the stiffness of the bearing is approximately the same as the stiffness of the surrounding structure. Therefore, the vibration of the entire device can be reduced by selecting suitable bearings (including preload and play) and configuration. The methods for reducing vibration are:
● Reduce the excitation force that causes vibration in the application
● Increase the damping of components that cause vibration to reduce resonance
Change the rigidity of the structure to change the critical frequency.
From actual experience, it is found that solving the bearing system problem is actually an activity that is linked between the bearing manufacturer and the manufacturer. After repeated running-in and improvement, the problem can be solved better. Therefore, in solving bearing system problems, we More advocates for cooperation and mutual benefit between the two parties.