A device to reduce positioning errors due to the machine tool compliance

Abstract

One of the main problems that large machine tool designers must face is the onset of deflection and vibration due to the forces involved during the process: the own weight of the elements of the machine, the cutting forces and the inertial forces. The last ones are especially relevant in the case of large and heavy machine tools with cantilever elements as rams or columns. To counteract these forces, the present work proposes the use of an inertial device, based on the rotation of two eccentric masses around the same axis. Hence, a simplified dynamic model of a column is first developed, and tested during a standard face milling operation. Then, the dynamic model of the device is also developed, and a Computed Torque Control is proposed to govern the action of the device. The simulations show that the use of this device has the potential to reduce drastically the effect of the inertial forces and even the lower frequency components of the cutting forces.