Parameter Design And Optimization Of Outer Ring Variable Diameter Raceway Of Cage Free Ball Bearings

Bearings are widely used in structural components of aircraft engines,electric shuttles and robots,and their mechanical properties play an important role in improving the system performance.Bearings in electromechanical equipment are developing in the direction of low friction,miniaturization,high load and adaptability to harsh environments,and the design of cage free ball bearings has emerged.This thesis starting from the motion stability of the rolling elements and inner ring in the cage free ball bearings,the theoretical design and experimental research of the outer ring raceway structure of cage free ball bearings are carried out.Firstly,design the variable diameter raceway parameters of cage free ball bearings.In order to avoid the axial displacement of the rolling element,according to the motion state of the rolling element when it passes through the variable diameter raceway,design the shape of the axisymmetric variable diameter raceway,and establish the structure parameters equations of the rectangular,shuttle and elliptic variable diameter raceways respectively.When a single variable diameter raceway is located in the load-bearing area or non-load-bearing area,analyze the force state of the rolling elements and inner ring,establish the mechanical model of the rolling elements and the displacement equation of the inner ring,determine the number of the rolling elements carried by the variable diameter raceway at different positions,and the influence on the displacement of the inner ring.According to the geometric parameters of the variable diameter raceways,the displacement equation of the rolling element’s center is established,which provides the basis for the establishment of energy equations.The distribution law of two and three variable diameter raceways is analyzed,combined with the shape and position of variable diameter raceways,a variety of variable diameter raceway parameters schemes are designed.Secondly,analyze the movement of the rolling elements and inner ring of the cage free ball bearing with different variable diameter raceways.Since the kinetic energy and potential energy of the rolling elements change when they roll through the variable diameter raceways,based on the change of energy,the equation of the distance between adjacent rolling elements is established,to determine the center distance between any adjacent rolling elements without collision.Combining the displacement equations of the mass center of the rolling element and the inner ring,the energy equations of the rolling element and the inner ring are established.Substitute them in the Lagrangian equation,the differential equations describing the motion of the rolling elements and the inner ring are obtained.Adopt the fourth-order Runge-Kutta method to solve the above differential equations,and to obtain the speed and displacement of the rolling element and the inner ring center.Analyze the velocity-displacement phase diagram of the rolling element and the inner ring,and initially optimize the variable diameter raceway parameters,to determine the variable diameter raceway parameter pair the influence of the stability of the cage free ball bearing system.Finally,in order to verify the correctness of the variable diameter raceway parameters design,the kinematics virtual simulation was performed on six cage free bearing models with different variable diameter raceway parameters.The variation range of the sphere center distance of adjacent rolling elements,the acceleration amplitude of the rolling elements and the speed and displacement fluctuation range of the inner ring center are analyzed to determine the final optimal result of variable diameter raceway parameters.Select the T10-60 bearing testing machine to test the cage free bearings with three variable diameter raceway shapes,and measure the vibration signals of the cage free bearings at different speeds,to determine the relationship between the shape of the variable diameter raceway,the speed and the vibration amplitude of the cage free ball bearing,and to verify the rationality of the theoretical optimization of the variable diameter raceway parameters.The parameter design of the local variable diameter raceway on the outer ring raceway and the optimization of the scheme are proposed in this thesis,and the research on the motion stability of each component of the cage free ball bearing is carried out to provide a reliable theoretical analysis and design direction for the performance optimization of the new type of bearing.