DYNAMICS OF MACHINE-TOOL SPINDLE BEARING SYSTEMS UNDER THERMAL GROWTH/

Increased use of high-speed machining creates the need to predict spin dle/bearing performance at high speeds. Spindle dynamic response is a function of the nonlinear bearing stiffness. Ar high speeds, thermal e xpansion can play an important role in bearing stiffness A complete be aring load-deflection analysis including thermal expansion is derived and is coupled with an analysis of spindle dynamic response. Steady-st ate temperature distribution is found from heat generation at the cont act point and from a quasi three-dimensional heat transfer model. Nume rical solutions give a good prediction of thermal growth and heat gene ration in the bearing. Predicted high-speed spindle frequencies show g ood agreement with experimentation. The effects of loading condition a nd bearing material type on bearing stiffness are also shown.