Capturing of Stress Distribution of Workpiece Under Ultrasonically Assisted Machining Condition

抄録

The stress distribution inside the workpiece under ultrasonic vibration assisted machining (UVM) condition is reported. Many researchers have reported the improvements of tool wear, burr generation and surface integrity by reduction of time-averaged cutting force under UVM condition. In this presentation, stress distribution inside the workpiece was observed by combining the photoelastic method and the pulse laser as light source synchronized with ultrasonically vibrating machining tool. The one shot of pulse laser with pulse width of 15nsec visualizes an instantaneous stress distribution by combining photoelastic method. Assuming that UVM phenomenon has high periodic repeatability for one period of ultrasonic oscillation and sweeping the phase of emission against to ultrasonic oscillation, 362 frames per one period of ultrasonic oscillation are captured. UVM will induced an intermittent cutting condition when vibration speed, which is proportional with frequency and amplitude, is sufficiently greater than feed rate of work, the stress distribution changed periodically and disappeared when the tool leaved from the workpiece. Shear angle and amplitude of cutting force change were strongly affected with relation between feed rate of workpiece and tool vibration speed.