Dynamic simulation of error attenuation in a smart tool post

Abstract

Elimination of tool vibration error from old turning machines can reduce industrial waste, save money, and improve design. A disc-stack smart material actuator is used in counteracting the radial disturbing cutting force. Solution of this problem using the finite element method proved to be of broader use compared with the previously investigated lumped-mass modelling in reaching justifiable conclusions for the dynamic response of the tool post. Magnitudes of structural stiffness ratios and their significance in designing an intelligent tool post for position error elimination are also evaluated. The time-dependent dynamic response of the tool post is investigated using pulse width modulation (PWM) as voltage excitation for smart material. Results indicated the importance of controlling the number of PWM cycles in each force period to have a favourable transient response. Solution outcome proved the importance of limiting the time delay between the actuation force and the applied voltage to have better control in position error elimination. Even though increasing the tool-post damping within a reasonable range can reduce tool-post error, the major improvement is noticed by modifying the PWM voltage and its time duration. The estimated static voltage in error elimination does not necessarily have to be identical with the dynamic applied voltage as obtained from the finite element method model.