Electrohydraulic Active Damping System

A major characteristic of machine tools is the relative dynamic flexibility at the tool centre point. Poorly damped resonance frequencies often cause self-excited vibrations, so called chatter vibrations, which derogate the machined surface and may cause tool breakage. In practice, typically the metal removal rate and therefore the productivity of the machine are reduced, in order to avoid such vibrations. This paper deals with an active damping system for the improvement of the dynamic flexibility of machine tools. The damping system is based on an electrohydraulic actuator, which combines comparatively large forces and a compact design. The control input for the actuator is determined from the acceleration measurement based on the concept of a so-called velocity feedback control. In experimental investigations, the depth of cut could almost be tripled.