In many cases, the size of the bearing bore has been specifically defined by the structure of the machine or device. Regardless of working life, static load safety factor and whether the economy will meet the requirements before the rest of the size and structure bearing the final selection, it will be subject to the size of calculus. The calculation includes actual load bearing capacity is compared with its load. Rolling static load refers to the rear bearing load is stationary (no relative movement between the inner and outer rings) or rotational speed is very low. In this case, the calculation raceways and rolling elements excess safety factor of plastic deformation. Most affected by dynamic load bearing, inner and outer rings relative motion, check the size of calculus fatigue damage raceways and rolling elements early safety factor. Only in special circumstances in accordance with DIN ISO 281 actual working life can be achieved in the name of life do calculus. Designed to focus on economic performance, it should make full use of the bearing capacity as possible. To take full advantage of the bearing, then the more important bearing size selection of calculation accuracy.
Static load bearing
Calculate the static load safety factor Fs help determine whether the selected bearing with sufficient static load rating. FS = CO / PO in which the static load safety factor FS, CO rated static load [KN], PO equivalent static load [KN] static load safety factor FS is to prevent rolling parts contact area appear permanent deformation of the safety factor. To be smooth, ultra-low noise bearings, requires a high value FS; requires only moderate operating noise of the occasion, the choice of a small number of FS; generally recommend using the following values: FS = 1.5 ~ 2.5 for low noise levels FS = 1.0 to 1.5 for routine noise level FS = 0.7 ~ 1.0 for medium noise levels rated static load CO [KN] is listed in the table for each different specifications of bearings. The load (for radial bearings is a radial force, in terms of the thrust bearing axial force), the theoretical pressure in the center of the rolling elements and raceway contact area is generated: -4600 N / MM2 self-aligning Ball bearing -4200 N / MM2 other types of ball bearings -4000 N / MM2 all roller bearings under the influence of static load rating of CO, in the largest part of the rolling elements and bearing raceway contact area, the resulting total plastic deformation of about thousandth the diameter of the rolling elements. Equivalent static load PO [KN] is a theoretical value, in terms of the radial bearings radial force, in terms of the thrust bearing axial and centripetal force. PO stress at maximum load rolling element and raceway contact area centers arising, in combination with the actual load was produced by the same stress. PO = XO * F r + Ys * Fa [KN] wherein PO equivalent static load, Fr radial load, Fa axial load, units are kN, XO radial coefficient, YO axial factor.
Dynamic load bearing
Basic dynamic load bearing standard calculation method specified in DIN ISO 281 is material fatigue failure (appears pits), life expectancy is calculated as follows: L10 = L = (C / P) P [106 Switch] where L10 = L nominal rating life [106 turn] C dynamic load rating [KN] P equivalent dynamic load [KN] P life exponent L10 is converted 1,000,000 units nominal rating life [106 turn] C dynamic load rating [KN] P life exponent L10 is 1000000 rev nominal rated life. For a large group of the same type of bearing it, of which 90% should meet or exceed this value. Dynamic load rating C [KN] can be found in each type parameter list of the bearing under the load action, bearing rating life can reach 1 million revolutions. Equivalent dynamic load P [KN] is a theoretical value, in terms of the radial bearings radial force on the thrust bearing is axial force. Its orientation, size constant. Bearing life is the same as the actual load combination effect equivalent dynamic load under the action. P = X * Fr + Y * Fa where: P equivalent dynamic load, Fr radial load, Fa axial load, units are kN, X radial factor, Y axial factor. Different types of bearings of X, Y value and the equivalent dynamic load calculation basis can be found in all kinds of bearings tables and preface. Ball bearings and roller bearing life index P vary. For ball bearings, P = 3 against rolling bearings, P = 10 /
