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Analysis of the influence of noise caused by the limiting speed of rolling bearings

The raceway sound of bearings and its control methods. The raceway sound is a smooth and continuous sound produced by the rolling element rolling on the raceway surface when the shaft is in operation. It is a unique basic sound that occurs in all rolling bearings. The general bearing sound is the combination of raceway sound and other sounds. The raceway sound of ball bearings is irregular, with a frequency above 1000Hz. Its main frequency does not change with the speed, but its total sound pressure level increases with the speed. For bearings with high raceway sound, the sound pressure level of raceway sound decreases with increasing viscosity; For bearings with low raceway noise, the sound pressure level changes from decreasing to increasing when the viscosity increases to about 20mm2/s. The greater the rigidity of the bearing seat, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and dominant frequency of the raceway sound will sharply increase with the decrease of the radial clearance. The methods for controlling raceway noise include selecting low noise bearings, i.e. bearings with very low ripple, and carefully selecting the usage conditions. Rolling track noise often affects the noise of the entire machine, and reducing rolling track noise can reduce the noise of the entire machine.

The impact sound of rolling elements and its control methods. When larger models of ball bearings or cylindrical roller bearings operate at low speeds under pure radial load, due to the small centrifugal force of the rolling element, the rolling element in the non load zone will impact the cage or raceway and emit noise. But as the speed increases, this sound will disappear. The control methods for the impact sound of rolling elements include appropriately reducing radial clearance and using bearings with reasonable structures and compliant materials as cages.

Rolling sound of bearings and its control methods Rolling sound is a sharp metal friction sound that can occur in cylindrical roller bearings in all situations, mostly in larger types of bearings lubricated with grease. It is more likely to occur in lubricating grease with degraded base oil performance and almost never occurs in oil lubrication. In addition, it is more likely to occur in winter, when subjected to pure radial loads, in situations with large radial clearance, and depending on the size of the model, it is prone to occur within a specific speed range, both continuously and intermittently. Adopting special processing methods for the outer ring raceway can prevent the occurrence of rolling noise. If necessary, this type of bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, high-performance lubricating grease can be used, and the rigidity of the machine parts matched with the bearing can be improved.

1) Standard (G) level tolerance bearings;

2) Radial bearings only bear radial loads, thrust bearings only bear axial loads;

3) =0.1C (C is the basic rated dynamic load of the bearing);

4) Rigid bearing seat and shaft;

5) The lubrication and cooling conditions are normal.

When the bearing operates under a load condition of 0.1C, the contact stress between the rolling element and the contact surface of the raceway increases, resulting in an increase in the operating temperature of the bearing and a relative deterioration in the performance of the lubricant. Therefore, the limit speed of the bearing will correspondingly decrease. For the range of C/=10, due to the small decrease in the limit speed, it can not be considered, and the value should be taken as f1=1. For radial bearings subjected to combined loads, due to the increase in the number of rolling elements under load, friction resistance, heat generation, lubrication and cooling conditions, and the increase in force acting on the cage, the ultimate speed of the bearing must be adjusted by multiplying it by a reduction factor f2 based on the type of bearing and the size of the load angle.

If the limit speed and speed of the selected bearing cannot meet the usage requirements, certain improvement technical measures can be adopted to increase it to achieve satisfactory requirements. If the bearing tolerance level is increased; Increase the clearance appropriately; Using special materials and improving the structure of the cage; Change the lubrication method, such as using oil gas, oil mist, and spray lubrication; Improve cooling conditions, etc.

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