Analysis And Mechanism Study On Sliding Damage Of A Certain Type Of Aero-engine Main Shaft Bearing

Spindle bearings,as the key part of aero-engine main shaft system,its working conditions are severe.With the development of aero-engines in the direction of higher speed,higher thrust weight ratio,the bearing failure caused by skid damage was prominent,which seriously affects the performance and reliability of the aero-engines.At present,the spindle bearing from an aviation engine has frequently damaged caused by skidding.The wear marks on the inner raceway surface of the bearing were removed by grinding in the factory,and additional test run was carried out after this method(the test running conditions was unchanged).The rate of the skid damage bearing decreased obviously.However,the internal relationship between the method and the damage decrease is still unclear,and there is no research report on this aspect at home and abroad.Therefore,it is necessary to carry out the analysis of the damage mechanism of aero-engine spindle bearings,so as to provide theoretical guidance for the application of skid damage protection of aero-engine bearings.In this paper,we analysis the spindle bearing of an aero-engine through the tracking inspection of the assembly process of bearings and related components,a large number of data was analyzed.Since the skid damage of the bearing is considered to be the raceway/roller friction wear category,the contact between the raceway and the roller was simulated on the high-precision friction and wear test machine.Considering the influence of different working conditions on the friction and wear of raceway/roller,the friction and wear mechanism of raceway/roller is revealed combined with the tribological behavior and microscopic analysis.The specific conclusions are as follows:(1)The skid damage of spindle bearings is closely related to the assembly process of the dynamic balancing.The total balance before running-in process has a greater influence on the surface roughness of the inner ring,and the roughness is not significant.Before running-in process,the surface roughness Ra of inner raceway ranges from 0.045 ?m to 0.065 ?m,and the bearing skidding damage rate is higher.(2)In the dry test process,the friction coefficient changes with cycle number through three stages of initial,rising(fluctuation)and stable.The friction coefficient decreases with the increase of normal load.The friction coefficient increases with the increase of sliding frequency,surface roughness and displacement amplitude.At a larger sliding frequency or displacement amplitude,the friction coefficient fluctuates greatly before it enters a stable stage,which may be attributed to the fact that debris generated at the friction interface,causes the instability of the friction interface due to the untimely debris removal.When the increase of normal load,displacement amplitude and sliding frequency increase,wear is gradually intensified,and the surface roughness is opposite.The wear mechanism is mainly abrasive wear,oxidation wear and spalling(3)In oil lubrication,the friction coefficient curve shows four stages of running-in,rising,falling and stabilizing with the cycle number.The friction coefficient decreases with the increase of normal load and sliding frequency,and increases with the increase of displacement amplitude.At larger sliding frequency or smaller displacement amplitude,the friction coefficient fluctuates greatly in the stable stage,which may be attributed to the difficulty in forming a stable oil film on the interface of friction pairs.With the surface roughness increases,the friction coefficient decreases gradually in the stable stage,which may be attributed to the rougher surface.The easier the oil storage of friction pairs,and the better friction reduction effect.As the normal load increase,the wear gradually increases,and the amplitude of the displacement is opposite.The wear mechanism is abrasive wear and peeling.(4)Comparing with the dry test,friction coefficient increase “falling” stage during oil lubrication test process.In dry test process and oil lubrication test state,the influence of the normal load and displacement amplitude on friction coefficient in stable stage is consistent.In the dry test process,the value of friction coefficient in stable stage increases with the increase of sliding frequency.Under the oil lubrication test condition,the influence of sliding frequency on the value of friction coefficient in stable stage is not obvious.In both states,with the increase of surface roughness,the numerical variation of friction coefficient in the stable stage is opposite.Because of oil film protection,the wear mechanism of oil lubrication test is slight spalling and abrasive wear.