Vibration-Proof Design of Boring Bar With Multidegree-of-Freedom Dampers

Abstract

This paper proposes boring bars equipped with multiple-degree-of-freedom dampers in order to increase stability against machining chatter in boring operations. By using the dampers, the modal flexibility at the natural mode, having the greatest receptance, is divided into smaller modal flexibilities at multiple-degrees-of-natural modes. This theoretical analysis clarifies that the division of the modal flexibility into many natural modes results in (1) the decrease of the modal flexibility; (2) the increase of the damping ratio; (3) shift of the vector locus of the receptance frequency response along the real axis toward the positive direction. These changes occur at the natural mode having the greatest receptance value, producing a great increase in stability against machining chatter. Design procedures for the boring bars are described, and the effect of the dampers is demonstrated in actual cutting tests.