Modeling of rolling bearing defects in terms of rolling element slippage

The experience of rolling bearing diagnostics shows that vibroacoustic signal spectrum often contains the components not equal to the calculating defect, but close to them. At the same time the bearing dismantling indicates the presence of the defect, therefore amendment of the formulas for defect calculating is a very urgent task.

Usually at an early stage of bearing defect development the evidence of defect of only one of the rings emerges at first and only after that – of the other. Since the inner ring is farther from the point of measurement, under the same vibration level the inner ring defect will be more significant than the outer ring defect. In the spectrum frequency components typical for ring defects are often modulated by rotation frequency of rotor, which cause appearance of side bands.

The bearings are constructed to realize ‘clear’ rolling during their operation, i.e. to eliminate the slippage of balls and rollers against the rings. The slippage causes the increase of resistance, bearing rotation and decrease of its durability. ‘Clear’ rolling of unloaded bearings is observed in case the tangents to the points of contact on both sides of a ball or extensions of lines of the roller contact are crossed on the bearing axis. Emergence of the slippage between the rings and rolling element is connected with the construction features and Reynolds microslip caused by the deflection difference of contacting bodies. The analysis of rolling bearing kinematics shows that the values of defect frequencies do change. The frequency of outer holder defect calculated according to classical formulas, which do not consider rolling element slippage against the bearing rings, equals 214 Hz. The frequency will shift to 220 Hz if the slippage is considered.

The report presents a theoretical analysis of calculation of rolling bearing defect frequencies that enabled to develop a calculation model of rolling bearing defect frequencies considering rolling element slippage against the bearing rings.  

Kostyukov V.N., Zaitsev A.V. Modeling of rolling bearing defects in terms of rolling element slippage // Nauka, obrazovanie, biznes (Science, education, business). - 2007. - pp. 76-79

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