Abstract: To investigate the dynamic characteristics of rock cutting by vibrational disc cutter deeply, the effect of vibration application on rock cutting performance and the interacted force between rock and disc cutter are investigated through experiments, and the results show: the rock cutting force presents approximatively double broken line feature of contact stiffness; there are weak contact and local cutting behaviour between rock and disc cutter; the reasonable vibration application can improve cutting efficiency of disc cutter and reduce cutting torque distinctly. Further, the dynamic model of rock cutting by vibrational disc cutter is developed using spring, damp, mass and slider elements, and the continuous-dimensionless equations including five interaction statuses between disc cutter and rock are established. The bifurcation diagram, velocity, displacement, Poincare section and phase diagram under different conditions are obtained by solving the differential equations, which can conclude some results with experiments: the developed dynamic model can well reappear the rock cutting process by vibrational disc cutter; the cutting system mainly including periodic and chaos motions, the phase diagram, velocity and displacement of cutting system under chaos motion are irregular, and its rock breakage efficiency is generally low; the motion state and rock breakage efficiency alter with the variation of static force, dynamic force amplitude and vibration frequency accordingly; the optimal ranges of static force, dynamic force amplitude and vibration frequency can be obtained according to bifurcation diagram and rock breakage displacement, and the corresponding states of cutting system are always P-1-I-1-Pr-1 (one impact between disc cutter and rock in one period, and rock step-breakage once).

Key words: vibrational cutting, rock breakage, dynamic model, motion state, optimal parameters