Influence of depth of cut on elliptical ultrasonic vibration cutting mechanism

The influence of the depth of cut on the elliptical ultrasonic vibration cutting mechanism is analyzed through theoretical model, finite element simulation and cutting experiment. It is found that when the depth of cut is small, the influence of the rounded cutting edge must be taken into consideration, and the cutting process reveals the micro-machining characteristics. The kinematics model and dynamics model for orthogonal elliptical ultrasonic vibration cutting are established based on the micro-machining theory. In the proposed models, the cutting tool is firstly divided into four cutting zones: the elastic recovery zone on the flank face, the ploughing zone on the rounded cutting edge, the shearing zone on the rounded cutting edge, and tool-chip friction zone on the rake face. The cutting force in each zone is then calculated. Finite element simulations of the cutting process and cutting experiments are also conducted. Simulation results show that when the depth of cut is less than the minimum cutting thickness, the cutting process is dominated by elastic recovery and friction on the flank face and ploughing of the rounded cutting edge, without chip generation, with the thrust cutting force being greater than the principal cutting force. However, when the depth of cut exceeds the minimum cutting thickness and keeps increasing, the effects of rounded cutting edge shearing and tool-chip friction on the rake face gradually take the dominant place during the cutting process, while the principal cutting force exceeds the thrust cutting force and increases rapidly.