A new active control method is presented to suppress machining chatter, based on a principle of direct compensation of cutting force. The modification of the dynamic characteristics of machine tool structure and that of the cutting process dynamics due to cutting force compensation are theoretically analyzed, and their effect upon chatter stability is examined on the basis of graphical stability analysis.
The cutting force compensation system, composed of the cutting force sensor, the electric controller and the magnetic exciter as force generator, is designed and manufactured to realize theoretically required dynamic characteristics of the compensation system. Some S 45 C steel workpieces fixed at the end of a long slender arbor were turned on a engine lathe to see how the cutting process stability increased by compensation, while severe chatter vibration arose without compensation at any cutting speeds with depth of cut of O.2 mm. Cutting experiments show that machining chatter is suppressed almost completely by proper compensation at cutting speeds lower than 60 m/min, and the stability limit increases by several times even at higher cutting speeds up to 180 m/min.