Smart actuator stiffness and switching frequency in suppression of vibration of a cuttingtool

Abstract

Techniques for suppression of vibration in cutting tools can save old machines and enhancedesign flexibility in new manufacturing systems. Structural stiffness interaction, with theuse of smart materials, in an intelligent toolpost is investigated using the finiteelement method. The results proved the limited use of lumped modeling in drivingconclusions and developing a toolpost system for dynamic response control. A transientsolution is obtained for the toolpost response in which a smart material actuator isexcited using pulse width modulation (PWM) for voltage generation to counteractthe radial disturbing cutting force. Calculations showed that error eliminationand transient response control require a minimum number of PWM cycles ineach force period. Time delay between the actuation force and voltage has anadverse effect on error elimination, if it exceeds a certain limit. Increasing dampingwithin a reasonable range might not eliminate the transient response originatedby the voltage switching of the smart material actuator. The estimated staticvoltage in error elimination cannot necessarily be used in dynamic switching. Thetool bit to actuator stiffness and tool carrier (holder) to actuator stiffness ratiosare both preferred to be above ten when space and weight limitations do notexist.