Analysis On Roller End Face Wear-Out Failure In Aero- Engine Intershaft Bearings And Improvement Design Of Bearing

The intershaft bearings used in certain type aero-engines is the first bearings that adopts the technical of reverse rotation of inner and outer rings in our country,it is used to support high load rotators.During the long trial run of the engine,roller end face wear-out failure occurred many times,it severely shortened the life of the bearings and affected the function of the engine,and thus the delivery of the engine was delayed.Based on the appearance of the end faces where the failure occurs,this pater made a deep research on failure analysis,design improvement and experimental confirmation.First,this paper analyzed the results of the comparison between the appearance of the failure,dimension measurement,metallographic structure and hardness inspection of the intershaft bearings with those of the FAG bearings.Then this paper made a statistics of the failure.According to its working condition and structure features,we find out the main cause is the unbalanced moment of force that caused by rollers rotating at high speed in the engine.Rollers made so many contacts with the inner flange and the pockets of the cage that their torsional pendulum caused the wear-out failure of the bearings.Secondly,based on failure cause,comparison with FAG specimen and theoretical analysis,this pater put forward an improvement design.This design narrowed down the value of radial clearance and controlled the roller radial inclination angle;it narrowed down the run-out of the roller corner to the roller axis,and corner tolerance;it increases the degree of corner symmetry,improve the consistency of the roller corners,and controlled the dynamic balance of the rollers to ensure the operating stability of the bearings;it improved the machining precise of the inner flange and cage pockets;through optimizing the interspace between the roller and the flange,it determined the rational interspace range and make the contacts between roller end faces and flange in a stable condition,and to avoid abnormal wear.At last,it conducted an performance experiments of 50 hours,an intensified test rig verification of 200 hours,and an long trial run of 300 hour with the engine.It shows that no end face wear-out failure occurred by using theimproved bearings.It solved the technical problem of the intershaft bearings in this type engine.This improved technical promotes the development of the aerobearing design and manufacture and provide technical insurance for developing high performance engines.