ACTIVE CHATTER DAMPING IN PLUNGE GRINDING USING MAGNETIC ACTUATORS

In cylindrical plunge grinding with conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability. Initial vibration related to the dynamic behavior of the workpiece and machine copy on the grinding wheel, causing an increasing waviness due to uneven wear and therefore, an increasing vibration of the workpiece. These self-excited oscillations lead to many expensive true-running cycles in order to ensure high workpiece quality and process stability. In this context, we present an abrasion manipulation system for active vibration control using a self-built magnetic actuator to influence the tool wear and prevent the development of wheel-sided chatter. Estimation of the grinding wheel's surface waviness has been achieved using a surface model, which parameters are estimated by a recursive-least-square-algorithm (r1s), exclusively using data of workpiece movement. Using the estimated tool-surface-signal to predict forces onto the workpiece, it is possible to compensate them by the actuator and impend the development of waves on the wheel's surface. The concept has been applied to a standardized plunge grinding process demonstrating successful chatter suppression at a former instable process.