Development of Ultrasonic Elliptical Vibration Controller for Elliptical Vibration Cutting

A new ultrasonic vibration controller is elaborated for ultrasonic elliptical vibration cutting. A method is developed to remove cross talks between the two directional vibrations of the stepped vibrator excited in the same bending mode in two directions, so that the two directional vibrations can be controlled independently. A controller is fabricated to keep the elliptical vibration to have a desired locus, where the amplitudes of the two directional vibrations and their phase shift are kept to be desired values, and the vibration frequency is locked to an average value of their resonant frequencies. The developed vibration control system is applied to ultraprecision diamond turning of hardened die steel, and an ultraprecise mirror surface with a shape accuracy of less than 0.2 μm is obtained.