Adaptive self-excited vibrations suppression during milling

Abstract

The problem of the occurrence and rapid suppression of unstable self-excited vibrations arising in the process of milling is considered. It is assumed that tool (cutter) is connected with machine overarm by an elastic suspension, which is used for force sensation. The tool moves evenly along the work surface with a given pressure on it. Pressing of the cutter provides the necessary axial depth of cut. Uniform movement along the work surface provides the required tool feed. Unstable self-excited vibrations or chattering is a deterrent to increase productivity. In this paper we consider the possibility of promptly detecting the onset of unstable auto-oscillations from the amplitude spectrum of the sensor readings of the horizontal forces of interaction between the instrument and the working surface. The amplitude spectrum is obtained using the fast Fourier transform, which allows to determine the beginning of unstable processes in system. Timely change of the axial depth of cut allows to transfer the milling process into the stable zone.