Prediction Of Dynamic Performance Of Spindle System Under High-precision Heavy-duty On-line Milling

The high precision and heavy loaded on-line milling spindle system works in a large random environment,and there are no stable structure foundation and relative motion datum.The rail corrugation makes the milling cutter vibrate unevenly,which will affect the milling surface precision,so higher requirements for the dynamic performance of the spindle system is wanted.The work has set up the coupling dynamic model of the spindle system basing on its geometric model to identify each surface parameters and study the influence of the dynamic performance of the milling cutter spindle system.The main research content includes:(1)Static model has been established to analyze the static characteristics of the spindle system.Basing on the classical elastic mechanics theory,the load of the spindle system of the milling device and its bearings under the non-processing conditions and processing conditions have been calculated.The calculation has been studied to analyze the influence of the static and dynamic characteristics of the spindle of the milling cutter disk.(2)A coupled dynamic model of spindle system has been established to accurately analyze its dynamic characteristics.The dynamic model of each component of the spindle system has been established in considering of the structural characteristics of its components and the main shaft binding surface.On the basis of the contact characteristics of the contact joints and bearing,the equivalent spring damping unit has been used to establish the joint and bearing parts.The overall dynamics formula of the cutter spindle system has been derived from its mass matrix,stiffness matrix and damping matrix.In the end,the whole coupling dynamic model of the cutter head spindle system on the basis of beam element and solid element has been established.(3)The distribution of dynamic parameter of the cutter face spindle system has been identified and extracted to improve the accurate prediction of its dynamic performance.According to the third generation RCSA response coupling structure theory,the work has set up the coordinates of the contact surface along the contact length in order to extract the stiffness and viscous damping between the gear and the spindle of the cutter which are approximately equivalent to the ones of shrink fit binding surface between the gear and the spindle of the cutter head.The shrink fit model of the spindle of the gear milling cutter has been established using the finite element method.The load conditions such as force and torque have been applied to the model.The contact pressure and displacement of the interference joints are extracted to calculate its contact stiffness and contact damping,and the supporting stiffness of each bearing has also been calculated using the elastic mechanics.(4)The dynamic characteristics of the spindle system of the milling cutter head have been analyzed so as to provide reference for optimizing the milling stability.The modal analysis of the whole coupling system model of the spindle has been carried out,and the natural frequency and mode curve of the spindle rotor have been studied.The harmonic response analysis of the spindle system model has been carried out to obtain the radial displacement of each node of the spindle rotor under the actual excitation load as well as the intrinsic frequency and peak displacement of the spindle system under the peak response.