Study On Error Motion Model And Testing Method Of Rotor Shaft System With Multi-Support

The assembled bearing,as the core component of the spindle unit,is closely related to the rotating accuracy of spindle.Which is widely used on precision processing equipment and precision measuring instruments.The spindle unit,as the core functional components of mechanical system,plays a decisive role in machine tools and other mechanical system.In this dissertation,the invariants of R-pairs' discrete error motion are developed to the angular contact ball bearing and the spindle rotor-bearing system's rotational error motion.The applications of invariants in testing,evaluation,error modeling and accuracy testing are discussed.(1)The geometric properties of the discrete rotational error motion constrained by the Rpairs are studied.The invariants of the error motion,including the minimal spherical imagine curve and the minimal striction curve are proposed and used to describe the deviation between the rotational error motion and the ideal motion.The invariant accuracy is then defined,which makes the evaluation more objective and comprehensive,and the results are independent of the function points and the coordinate systems.Based on this invariants,the distribution characteristics of rotational errors in fixed sensitive direction are analyzed.(2)The rotational error model of angular contact ball bearing for accuracy characteristics is established,which considers comprehensively coupling effects of the bearing components' geometrical parameters and their errors,the physical properties of the components,the external loads,the elastic deformation of part structures and the bearing speed.This error model realizes the invariant accuracy analysis of the rotational error motion with their geometric physical constraint equation's solutions.Finally,this model reveals the function for the characteristic states of components and the rotational error motion.(3)The elastic error constraint model for accuracy characteristics of the spindle rotorbearing system is proposed.The time-varying stiffness characteristics of the bearing subjected to external loads,the mapping of the geometric error,the physical properties of the components and the elastic deformation of part structures are considered synthetically.This model reveals deformation compatibility relationship under the support of multi-bearings.It also provides the basis for the assembly process optimization and accuracy design.(4)The testing platform for measuring the accuracy of bearings is built.The kinematic geometrical model for testing rotational error motion with a master cylinder artifact is set up,and the six kinematic parameters of the error motion are calculated using the data measured.This testing platform realizes the comparison between the measured and simulated values of bearing rotational error motion under different axial loads and rotational speeds.In this dissertation,the invariant accuracy of the bearings and the spindle rotor-bearing system is studied.The influence of components' geometrical parameters and their errors,physical properties,elastic deformation of part structures and working loads on the error motion is revealed.The validity of the error constraint model is verified,which is of great significance to assembly process optimization and accuracy design.