On the occurrence of regenerative chatter vibrations.

Cutting forces and deflections of a workpiece are measured from the start of cutting operations and one of the important physical causes of regenerative chatter is found to be a small change of the cutting force that necessarily exists, even in a stable cutting condition. In a stable cutting condition the workpiece is slightly disturbed by a hammer blow, and the changes of the cutting forces and the workpiece deflections are simultaneously measured. Vibratory parameters of a workpiece, that is, spring constant, damping coefficient and so on are precisely measured, and more suitable equations of motion for chatter vibration are proposed. These proposed differential equations of motion are calculated by a digital computer for two initial conditions ; that is, first, the workpiece suffers a small disturbance of displacement ; second, the workpiece is disturbed by a hammer blow. Results of numerical calculations are compared with experimental results, and quantitative coincidence is derived.