Effect of spindle design on spindle dynamics and chatter stability

Spindle-bearing assembly is the most flexible component in machining centers and its dynamics directly affect the performance of the machines. Spindle geometry (outer and inner diameters, segment lengths) and, location of the bearing and their configurations are the crucial parameters that determine the spindle dynamics. Therefore, the selection of the optimum design parameters is the key factor for the spindle design procedures. In this study, a design methodology for the spindle-bearing assembly is offered for the optimized spindle dynamics. In this method, first, the spindle shaft is modeled using the analytical solution of Timoshenko beam and receptance coupling methods. Then, bearing dynamics are included using the structural modification technique. Using the developed analytical model, the effect of each design parameter on spindle dynamics is analyzed. In addition, the effect of operational conditions such as gyroscopic effects and centrifugal forces are included in the structural dynamics model and variations of the spindle dynamics under operational conditions are also considered during the simulations. Simulations show that the proposed method along with the sensitivity analysis can be efficiently used for the selection of the optimum spindle-bearing assembly configuration.