Research On Dynamic Characteristics Of Oscillating Ball Bearings For Aircraft

The pitch,direction,and attitude of the aircraft are directly controlled by the bearings that oscillate or rotate at low speed.Aerospace bearings have special working conditions,high technical requirements and high reliability requirements.And it is required that the life of the bearing should be the same with the aircraft.This places higher requirements on the accuracy,life and reliability of the rolling bearings,which are the basic key components of the aircraft.The dynamic characteristics of the bearing directly affect the orientation and positioning accuracy and life of the whole machine.Therefore,it is necessary to perform dynamic analysis on the oscillating bearing for the aircraft so that the bearing has good dynamic performance under oscillating conditions.To study the dynamic characteristics of bearings for the aircraft under oscillating conditions,based on the theory of rolling bearing dynamics,the nonlinear equations of ball bearings under oscillating conditions are established,and the GSTIFF(Gear stiff)variable step integration algorithm is used for it.The dynamic characteristics of the bearings which are used in the aircraft system,such as the slip,the collision between the ball and the cage,and the friction torque of the bearing,can be obtained with this method.In this paper,a certain type of ball bearing for aircraft is taken as an example to study the influence of bearing structure parameters and working condition parameters on the dynamic characteristics of the bearing.Research indicates that: The skidding of the ball,the collision between ball and cage and the friction torque under the oscillating condition are obviously larger than those under the smooth running condition;The maximum skidding of the ball always in the non-loading area is larger than that always in the loading area,and of which the ball continuously enters and exits is in between.As the clearance increases,the skidding of the ball increases sharply and then increases slowly.The increase of the shifting time,radial load and lubricant coefficient,as well as the decrease of stability speed are beneficial to reduce the skidding of the ball during the oscillating motion;The cage collision with the ball at three different positions under the oscillating condition can be regarded as the superposition of the driving force or the blocking force and the impact force;The maximum collision force between the cage and the ball always in the non-bearing area is greater than that of the ball always in the bearing area,in between which is that of the ball continuously enters and exits the loading area;As the gap of the cage pocket increases,the collision force between the cage and the ball at different positions increases continuously;To reduce the stability speed of the ring,the lubricant coefficient and the radial load,or to increase the shifting time is beneficial to reduce the collision between the ball and the cage during the oscillating process;The frictional torque of the bearing decreases rapidly with the increase of the radial clearance;with the increase of the cage pocket clearance,the bearing friction torque increases first and then decreases and then increases;the decrease of the lubricant coefficient,the stability speed and radial load,as well as the increase of the shifting time are beneficial to reduce the friction torque of the bearing during the oscillating motion.Finally,the accuracy of the dynamic model of the oscillating ball bearing for the aircraft established in this paper is verified by comparing the experimental results with the simulation results.The simulation model of the bearing using in the aircraft system considers the lubrication and elastic deformation of the cage during oscillations.The internal force is completely processed,and the time-varying speed under the oscillating condition is simulated.By establishing an effective three-dimensional parametric simulation model,the dynamic performance of oscillating bearings is analyzed,which provides theoretical guidance for the design and use of oscillating aircraft bearings.