Development of a Hydraulic Chambered, Actively Controlled Boring Bar

Abstract

A major problem in the active control of the boring process is developing a practical method of providing small-amplitude tool-tip positioning. The main thrust of the underlying research work is the design, development and evaluation of a new actuation concept for active control of the boring operation. The actuation concept was implemented using a special boring bar with two internal longitudinal hydraulic chambers. A pressure difference between these two chambers provides the driving force to create the desired tool-tip motion. Using a measure of the dynamic cutting force, the controlled boring bar system was successful in making improvements over the uncontrolled boring bar’s cutting performance in terms of regenerative chatter control. The cutting tests used in this thesis were plunge cuts in mild steel. The controlled level of improvement was smaller than was anticipated. The problem was considered not a fault of the actuation scheme, but a result of a non-optimal combination of the servovalve, measurement system and controller. Further work in these areas should yield considerably improved results using the new actuation concept.