Nonlinear Behaviors of the Machine-Tool Spindle System Supported by Ball Bearings With Clearance

In this effort, the nonlinear dynamics of a machine-tool spindle system supported by ball bearings is investigated. Considering the loss of contact between the inner race and ball in the ball bearing, the system is described by a set of second order nonlinear differential equations with piecewise stiffness and damping. The nonlinear responses of the system exhibit the softening behavior due to the loss of contact. As the initial preload is applied to the spindle system and the balls are fully contacting with the inner race of the bearing, the nonlinear responses of the system switche to the hardening behavior. Due to the 3/2 nonlinearity, resonance are found when the excitation frequency is close to one-third of the first natural frequency, one-half of the first nature frequency, two-third of the first natural frequency, and the first natural frequency. The route of the period-doubling bifurcation to chaos and the tori doubling process to chaos which usually occurs in the impact system are also observed in this spindle-bearing system.