Size selection
In many cases, the inner bore size of the bearing has been specifically defined by the construction of the machine or device. Regardless of the working life, the static load safety factor and the economy are all required, the size calculation must be carried out before the final selection of the remaining dimensions and structural form of the bearing. This calculation involves comparing the actual bearing load to its load capacity. The static load of a rolling bearing means that the bearing is stationary after loading (no relative movement between the inner and outer rings) or the rotation speed is very low. In this case, the safety factor of excessive plastic deformation of the raceway and the rolling element is calculated. Most of the bearings are subjected to dynamic loads, the inner and outer rings are relatively moved, and the dimensional calculations check the safety factors of early rolling damage of rolling raceways and rolling elements. Nominal life calculations are performed on the actual achievable working life according to DIN ISO 281 only in special cases. For economic performance-oriented designs, the bearing capacity of the bearing should be utilized as fully as possible. To make full use of the bearings, the more accurate the calculation of the bearing size is.
Static load bearing
Calculating the static load safety factor Fs helps determine if the selected bearing has sufficient static load rating. FS =CO/PO FS static load safety factor, CO rated static load [KN], PO equivalent static load [KN] Static load safety factor FS is a safety factor to prevent permanent deformation of the rolling parts contact area. For bearings that must run smoothly and have extremely low noise, the value of FS is required to be high; in the case of medium running noise, a smaller FS can be used; the following values are generally recommended: FS=1.5~2.5 for low noise level FS =1.0~1.5 is suitable for conventional noise level FS=0.7~1.0 for medium noise level. Static load rating CO[KN] is listed in the table for each type of bearing. The load (radial force for radial bearings and axial force for thrust bearings), the theoretical pressure generated at the center of the rolling element and raceway contact area is: -4600 N/MM2 self-aligning Ball bearing-4200 N/MM2 Other ball bearings-4000 N/MM2 All roller bearings have a total plastic deformation amount at the maximum load-bearing part of the rolling element and raceway contact area under the action of static static load CO. It is one ten thousandth of the diameter of the rolling element. The equivalent static load PO[KN] is a theoretical value, which is a radial force for a radial bearing and an axial and centripetal force for a thrust bearing. The stress generated by the PO at the center of the maximum load-bearing contact area of the rolling elements and raceways is the same as the stress generated by the actual load combination. PO=XO*F r+Ys*Fa[KN] where PO equivalent static load, Fr radial load, Fa axial load, unit is kilonewton, XO radial coefficient, YO axial coefficient.
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