Dynamic analysis and stability prediction of nonlinear feed system coupled with flexible workpiece

The workpiece is prone to self-excited vibration when turning a slender shaft and the flexibility cannot be ignored in this condition. In this paper, a new flexible tool-workpiece system is developed to investigate the nonlinear dynamics and chatter stability for in a turning process. The piecewise-nonlinear restoring function of the tool system is derived by calculating axial deformations and forces of the ball screw feed system. With the variation of time delay, the dynamic behaviors of the cutting system are analyzed by numerical method, which manifests as periodic, quasi-periodic, and chaotic motions. Through determining the critical chip width under different spindle speed, the stability lobe diagram (SLD) of nonlinear system is obtained to distinguish stable and unstable states. In addition, the dynamic characteristics and SLD of nonlinear system are compared with linear system. An experiment is carried out to observe the vibration phenomenon under stable and unstable turning conditions and verify the accuracy of stability prediction.