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Prediction of Regeneration Chatter Stability of Composite Boring Bar

The deep holes cutting process by metal boring bar is usually limited due to the development of chatter vibration. This is because metal boring bar has not only low bending stiffness but also low structural damping. A chatter stability prediction of composite boring bar under regenerative cutting force is presented. Based on the theory of Euler-Bernoulli beam, the regenerative chatter dynamic model of composite boring bar is proposed, and the solution formula of the limited cutting depth and corresponding spindle speed is given. The dynamic stability lobes of the composite boring bar are obtained by numerical calculation. The results indicate that composite boring bar exhibits efficient chatter stability than metal boring bar. Chatter stability is closely related to fiber ply angle. It is demonstrated that when ply angle is 0o, carbon/ epoxy reaches its critical cutting depth, and for graphite/ epoxy boring bar about 25o of ply angle gives its critical cutting depth, It is also demonstrated that stability boundary decreases as the ratio length and diameter increases. Finally, the prediction results of stability are compared with those from the dynamic stiffness and time-domain response, agreement is found.