The essence of NSK bearing noise

Core Tip: For the use of bearings, it is very common to generate noise. Even the low-noise bearings in NSK bearings have the same situation. So why is there noise? Today I am
For the use of bearings, it is very common to generate noise. Even the low-noise bearings in NSK bearings have the same situation. So why is there noise? Today I will introduce the essence to you.
    (1) Bearing track sound and its control method Rolling sound is a kind of slippery continuous sound that the rolling element rolls on the raceway surface when the bearing is running. It is the unique basic sound that all rolling bearings will produce. . The general bearing sound is the rolling sound plus other sounds. The ball bearing's raceway sound is irregular, the frequency is above 1000Hz, its main frequency does not change with the speed, but its total sound pressure level increases with the increase of the speed. For bearings with large rolling sounds, the sound pressure level of the raceway sound decreases with the increase of viscosity; while for bearings with small raceway sound, the sound pressure level decreases when the viscosity increases to about 20 mm2/s or more. For the increase. The greater the rigidity of the bearing housing, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and main frequency of the raceway sound will increase sharply as the radial clearance decreases. The method of controlling the rolling sound is to select a low-noise bearing, that is, a bearing with a small waviness, and carefully select the conditions of use. The raceway sound often affects the noise of the entire machine, and reducing the raceway sound can reduce the noise of the entire machine.
    (2) Impact sound of rolling element and its control method When the larger type of ball bearing or cylindrical roller bearing runs at low speed under pure radial load, the rolling element in the non-load area will be small due to the small centrifugal force of the rolling element. Noise is generated by impacting the cage or raceway. But as the speed increases, the sound will disappear. The control methods for the impact sound of the rolling element are: appropriately reducing the radial clearance, and using a bearing having a reasonable structure and a flexible material.
    (3) Bearing rolling sound and its control method Rolling sound is a harsh metal friction sound that can occur in cylindrical roller bearings in all occasions, most of which occur in grease-lubricated larger type bearings, and in base oil performance Deteriorated grease is more likely to occur and hardly occurs when oil is lubricated. In addition, it is more likely to occur in winter. When subjected to pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a certain speed range depending on the size of the model, and it will occur continuously. It will appear intermittently. Special processing methods for the outer ring raceway can prevent the occurrence of rolling noise. If necessary, the bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, and the grease with excellent performance and the rigidity of the bearing device can be improved.

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Why is the bearing bad?

Core Tip: Bearings are precision parts and only some of the bearings are damaged in practical applications. Most of the reasons for bearing damage are much higher than the original estimated load, non-effective sealing, too tight
Bearings are precision parts and only some of the bearings are damaged in practical applications.

Most of the bearings are damaged for many reasons - beyond the original estimated load, non-effective seals, too tight bearing clearance caused by too small bearing clearance. Any of these factors have their particular type of damage and leave a special mark of damage. Therefore, inspecting the bearing of the damaged shaft, in many cases, its possible cause can be found. In general, one-third of the bearing damage is caused by fatigue damage, and the other third is caused by poor lubrication. The other third is due to contaminants entering the bearing or improperly installed.

However, these types of damage are also related to industry. For example, most of the pulp and paper industry is due to poor lubrication or contamination resulting in bearing damage rather than material fatigue. Bearings are precision parts, so they require a very cautious attitude when used. Even if high-performance bearings are used, if they are used improperly, the expected performance will not be achieved and the bearings will be damaged easily. Therefore, the following matters should be noted when using bearings:

    1. Keep the bearings and their surroundings clean. Even if tiny dust that is invisible to the naked eye enters the bearings, it will increase the wear, vibration and noise of the bearings.

    Second, use the installation carefully and carefully Do not allow strong stamping, do not allow the hammer to directly hit the bearing, not allowed to pass the pressure through the rolling elements.

    Third, the use of appropriate and accurate installation tools Try to use special tools, try to avoid the use of cloth and short fibers and the like. Fourth, to prevent the corrosion of the bearing When taking the bearing directly by hand, you should wash the sweat on your hands and apply it with high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention.

   However, under certain special operating conditions, bearings can achieve longer life than traditional calculations, especially at light loads. These special operating conditions are when the rolling surfaces (tracks and rolling elements) are effectively separated by a lubricant film and the surface damage caused by contaminants is limited. In fact, under ideal conditions, so-called permanent bearing life is possible. Bearing life The life of a rolling bearing is defined by the number of revolutions (or the number of hours of operation at a certain speed): Bearings within this life are subject to initial fatigue damage (flaking or missing) on ​​any of their bearing rings or rolling elements. However, whether in the laboratory test or in actual use, it can be clearly seen that the same bearing under the same working conditions has a different actual life. In addition, there are several different definitions of the bearing "life", one of which is the so-called "working life", which means that the actual life that a bearing can reach before it is damaged is caused by wear and damage, usually not caused by fatigue, but Caused by wear, corrosion, seal damage, etc.

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