Analysis Of The Impact Of Cage In Aeroengine Roller Bearings

Bearings have important influence on the flight performance and safety of theaircraft engine system. According to statistics, the breakage of cage is an importantcause of bearing failure. Especially in high-speed bearings, the frequently impactbetween cage and rollers heavily influences bearing’s performance. So the study on thedynamics of the cage is of great significance. But the research on the impact of the cageis less so far.In this paper, the impact between cage and rollers is a key consideration and asimple dynamic model of the cage in cylindrical roller bearing is established. Themotion and impact of cage and rollers are analyzed and the influences of workingcondition and structure parameters on impact force are studied. Results of this work canbe used as a reference for accident analysis and design of cage.The dynamics of cylindrical roller bearings is analyzed, based on the simulatedstatics analysis and the simulated dynamics analysis theory of antifriction bearings. Theimpact between cage and rollers is outstanding considered. The cage and rollers areregarded as a discontinuous impact vibration system. The other forces are regarded asthe external forces of the system and are simplified according to the actual movementand deformation in bearings. In this way, a simple dynamic model of the cage incylindrical roller bearing was established.An actual example is choosed, and using fixed-step4-rank Runge—Kuttaalgorithm, through MATLAB programming, the nonlinear differential equations of thesystem are solved. The situation of no cage, and the simple model which is a2-DOFsystem of cage and single roller,and the model of Multi-DOF system consisted of cageand all the rollers are solved. The motion characteristics of cage and rollers arecompared and analyzed.The dynamics properties of the system are studied. The period motion andbifurcation of the system under different rotational speed or radial load are analyzedthrough the phase trajectory and Poincaré map theory. The skid of cage under differentworking condition is also analyzed. The most easily broken place of the cage is knownthrough the analysis of the impact force. By calculating the impact force of the cagepocket beam under different working condition, the influence of working condition onthe fatigue life and the wear of cage are studied.By calculating the maximum impact force and average impact force of the cagepocket beam under different cage pocket clearance, coefficient of restitution betweencage and roller, or the mass of cage and rollers, the effects of this parameters on thedynamic performance and reliability of the cage are studied. The influence of impact on the reliability of the cage is analyzed according to theory mechanics. The maximumstress of the cage pocket beam is calculated and the risky section to be broken of thecage pocket beam is analyzed. The bending fatigue strength of the cage pocket beam ischecked, and the effects of the roller skew and the pocket clearance on the bendingfatigue strength of the pocket beam are studied.