Thermal-mechanical Modeling For High Speed Motorized Spindle

High speed spindle has been widely used in modern manufacturing industry for theadvantages of high efficiency, high precision and high stiffness. However, severemechanical-thermal coupling in the spindle usually leads to failure. The complexinteractions and the constantly changing characteristics in spindle system make it difficultto design. Only by building a high accurate mechanical-thermal coupling model andstudying the mechanical and thermal interactions in the spindle, can we achieve thepurpose of advising high-speed spindle structure design and operation conditions setting.The traditional spindle models are lacking in an overall consideration of mechanicaland thermal characteristics, and the coupling parameters in the joint surface are constant,which cannot change by the operation conditions. Due to these problems, we present amechanical-thermal high-speed spindle modeling method with consideration of themechanical and thermal characteristics in the movable and fixed joint surface based on thefinite element method. The main research works are shown as follows:Firstly, the main components and their functions in the spindle were introduced. Theinteractions between the components were analyzed, and a framework of the high-speedspindle model was proposed.Secondly, a theoretical model of movable joint surface concerning the relationship ofbearing ball load to bearing contact stiffness and contact resistance was proposed, whichbased on the Hertz contact model and Jones bearing model. And a model of fixed jointsurface concerning the load, stiffness and thermal contact was proposed based on thefractal theory and W-K contact model.Then, based on the former study, a mechanical-thermal coupling model forhigh-speed spindle was established in ANSYS software. The movable and fix joint surfacetheoretical model were embedded into the FEM model, and the method of updatingparameters in joint surface was designed. Simulation process of the FEM model wasproposed.Finally, an experiment was carried on the spindle of HMC80machine tool to verifythe accuracy of the new model. The experiment results showed that the proposed model was effective in temperature rising and deformation prediction.