Study on the stiffness and fatigue life of tapered roller bearings with roller diameter error

Author(s):  
Van-Canh Tong ◽  
Seong-Wook Hong

Geometric imperfection is a common problem in manufacturing of rolling element bearings. In particular, roller geometric errors frequently occur because a large number of rollers with relatively small size are engaged in a bearing. However, computational tools for rolling bearing characteristics take into account ideal bearings without any geometric error. In this study, the stiffness and fatigue life of tapered roller bearings were investigated with consideration for the effects of roller diameter errors possibly induced during manufacturing process. To this end, a general model for tapered roller bearings having rollers with diameter error (or defective rollers) was developed that can reflect the time-varying stiffness due to the roller error effects. The effects of the number of defective rollers, error magnitude, and position of defective rollers on the stiffness and fatigue life were investigated. Computational results showed that even small roller diameter errors appreciably alter the tapered roller bearings internal load distributions and therefore the stiffness and fatigue life of tapered roller bearings.

2018 ◽  
Vol 3 (2) ◽  
pp. 947-960 ◽  
Author(s):  
Jonathan Keller ◽  
Yi Guo ◽  
Zhiwei Zhang ◽  
Doug Lucas

Abstract. In this paper, the planetary load-sharing behavior and fatigue life of different wind turbine gearboxes when subjected to rotor moments are examined. Two planetary bearing designs are compared – one design using cylindrical roller bearings with clearance and the other design using preloaded tapered roller bearings to support both the carrier and planet gears. Each design was developed and integrated into a 750 kW dynamometer tests, the loads on each planet bearing row were measured and compared to finite-element models. Bearing loads were not equally shared between the set of cylindrical roller bearings supporting the planets even in pure torque conditions, with one bearing supporting up to 46 % more load than expected. A significant improvement in planetary bearing load sharing was demonstrated in the gearbox with preloaded tapered roller bearings with maximum loads 20 % lower than the gearbox with cylindrical roller bearings. Bearing life was calculated with a representative duty cycle measured from field tests. The predicted fatigue life of the eight combined planet and carrier bearings for the gearbox with preloaded tapered roller bearings is 3.5 times greater than for the gearbox with cylindrical roller bearings. The influence of other factors, such as carrier and planet bearing clearance, gravity, and tangential pin position error, is also investigated. The combined effect of gravity and carrier bearing clearance was primarily responsible for unequal load sharing. Reducing carrier bearing clearance significantly improved load sharing, while reducing planet clearance did not. Normal tangential pin position error did not impact load sharing due to the floating sun design of this three-planet gearbox.


Author(s):  
D Nélias ◽  
I Bercea

A general theoretical model to analyse the internal interactions within various types of double-row rolling bearing was presented in Part 1 of this two-part paper. The performance of the rolling bearing model is shown here for a bearings-flexible-shaft system. Double-row tapered roller bearings (in a back-to-back or face-to-face arrangement) were chosen as support bearings. Investigations of the effect of shaft mounting on support bearings (cantilever or straddle arrangement) and on the effect of preload are presented and discussed. It is shown that, when an optimum value of preload or fatigue life of the bearing arrangement is expected, shaft bending cannot be ignored.


1972 ◽  
Vol 94 (2) ◽  
pp. 181-186 ◽  
Author(s):  
H. Zantopulos

A comprehensive analytical and experimental study of the effect of misalignment on load distribution and fatigue life of tapered roller bearings is presented. Included are the effects of truncation of crowned rollers and edge of contact stresses. Bearing life tests, involving approximately 500 bearings, were run at various loads and misalignments to obtain sufficient test data to substantiate the analytical results.


2018 ◽  
Author(s):  
Jonathan Keller ◽  
Yi Guo ◽  
Zhiwei Zhang ◽  
Doug Lucas

Abstract. In this paper, the planetary load-sharing behaviour and fatigue life of different wind turbine gearboxes when subjected to rotor moments are examined. Two planetary bearing designs are compared – one design using cylindrical roller bearings with clearance and the other design using preloaded tapered roller bearings to support both the carrier and planet gears. Each design was developed and integrated into a 750-kilowatt gearbox. In field-representative dynamometer tests, the loads on each planet bearing row were measured and compared to finite element models. A significant improvement in planetary bearing load sharing was demonstrated in the gearbox with preloaded tapered roller bearings with maximum loads 20 % lower than the gearbox with cylindrical roller bearings. Bearing life was calculated with a representative duty cycle measured from field tests. The predicted fatigue life of the eight-combined planet and carrier bearings for the gearbox with preloaded tapered roller bearings is 3.5 times greater than for the gearbox with cylindrical roller bearings. The influence of other factors such as carrier and planet bearing clearance, gravity, and tangential pin position error is also investigated. The combined effect of gravity and carrier bearing clearance was primarily responsible for unequal load sharing. Reducing carrier bearing clearance significantly improved load sharing, while reducing planet clearance did not. Normal tangential pin position error did not impact load sharing due to the floating sun design of this three-planet gearbox.


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