Dynamic Analysis Of Cylindrical Roller Bearings At Stop Stage

Bearing-rotor system is one of the widely used main shaft systems in aero-engine in modern time. The cylindrical roller bearing is used on main shaft in aero-engine because of its high speed performance. At the stop stage of aero-engine, the happened frictional wear between ring and rollers as well as the concussion, howling, wear and fatigue failure of cage always lead to the early failure of bearings. Therefore, as a key support structure of main shaft systems in aero-engine, the study of dynamic characters of cylindrical roller bearing at stop stage is very indispensable.Based on the dynamic theory of rolling bearings, the dynamic analysis model of cylindrical roller bearings at stop stage under large acceleration was established. And under ground work, the dynamic simulate model of cylindrical roller bearings at stop stage under large acceleration was also established. And the force and angular speed of cage at some point was extracted in the deceleration phase as the boundary conditions of finite element model of cage, the finite element model of cage was established in order to analyze the cage strength.Taking certain type of cylindrical roller bearing as an example, the influences on cage slip ratio and strength caused by material of cage, working conditions and structural parameters of cylindrical roller bearing were investigated at stop stage. And the results were proved by test. The results show: 1 there is a time delay when the rotation speed of cage changes along with the inner ring rotation speed, as a result, the slip ratio of cage changes from positive to negative and the negative slip ratio maximize at some point; 2 the cage material and pocket clearance have small effects on cage slip ratio; 3 the cage slip ratio increases with the rise of angular acceleration of inner ring and radial clearance, and decreases with the radial load, supply oil temperature and guide clearance at static stage of bearing;the cage negative slip ratio increases with the rise of angular acceleration of inner ring, radial clearance and guide clearance, and decreases with the radial load and supply oil temperature at stop stage of bearing; 4 the cage stress is produced mostly by centrifugal force in static stage of bearing, but in stop stage, cage stress is produced mostly by collision between rollers and cage, and the stress is several times larger than in the static stage; 5 when working in same condition, steel cage contributes more to cage strength; 6 the cage stress decrease and then increase with the increase of supply oil temperature, and there is a reasonable supply oil temperature to get the lowest cage stress; 7 Reasonable choices should be made of radial clearance, load and supply oil temperature for cage stress at stop stage can be significantly reduced when the traction between raceway and cage as well as rollers are larger than a certain value.