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In many cases, the bore size of the Size Parameters bearing has been specifically limited by the structure of the machine or device.
No matter whether the working life, static load coefficient and economy meet the requirements, the size Size Parameters calculation must be carried out before the final selection of other sizes and structural forms of bearings. The calculation includes comparing the actual load of the bearing with its load capacity.
The static load of rolling bearing Size Parameters means that the bearing is static after loading (there is no relative movement between the inner and outer rings) or the rotation speed is very low. In this case, the coefficients of excessive plastic deformation of raceway and rolling element are calculated.
Most bearings are subject to dynamic load, and the inner and outer rings Size Parameters make relative motion. The early fatigue damage coefficient of raceway and rolling element is checked by dimensional calculation.
Only in special cases can the nominal service life be calculated according to DIN ISO 281. For the design that pays attention to economic performance, we should make full use of the Size Parameters bearing capacity as much as possible. In order to make full use of the bearing, the calculation accuracy of bearing size selection is more important.
FS =CO/PO
Where, FS static load coefficient, CO rated static load [kn], Po equivalent static load [know] Size Parameters The static load factor FS is a factor to prevent permanent deformation in the contact area of rolling parts.
For bearings that must run smoothly and have very low noise, the value of FS is required to be high; When only Size Parameters medium operation noise is required, a smaller FS can be selected; The following values are generally recommended:
FS = 1.5 ~ 2.5, applicable to low noise level
FS = 1.0 ~ 1.5, applicable to conventional noise level
FS = 0.7 ~ 1.0, applicable to medium noise level
The rated static load CO [kn] has been listed in the table for each type and specification of bearing. The Size Parameters theoretical pressure generated by this load (radial force for radial bearing and axial force for thrust bearing) at the center of the contact area between rolling element and raceway is:
-4600 n / mm2 self-aligning ball bearing
-4200 n / mm2 other types of ball bearings
-4000 n / mm2 all roller bearings
Under the action of rated static load Co, the total plastic deformation at the large bearing part of the contact area between the rolling element and the raceway is about one ten thousandth of the diameter of the rolling element.
Equivalent static load Po [kn] is a theoretical value, which is radial force for radial bearing and axial and radial force for thrust bearing. The stress generated by Po in the center of the large bearing contact area of the rolling element and raceway is the same as that generated by the actual load combination.
PO=XO*F r+Ys*Fa[KN]
Among them, Po equivalent static load, FR radial load and FA axial load are all in Kilonewtons, XO radial coefficient and yo axial coefficient.