Dynamic Compensation of Spindle-Integrated Force Sensors

This paper presents a dynamically compensated Spindle-Integrated Force Sensor system to measure cutting forces. Piezo-electric force sensors are integrated into the stationary spindle housing to measure cutting forces in three directions. The transfer function of the spindle structure between the cutting forces acting on the tool tip and the measured forces at the spindle housing are identified. Using the cutting force signals measured at the spindle housing, a Kalman filter is designed to filter the influence of structural modes on the force measurements. The frequency bandwidth of the force measurement system is significantly increased with the proposed sensor and the signal processing method. Milling experiments with tooth passing frequencies up to 1000 Hz are presented with effective removal of cutting force distortions caused by three structural modes of the spindle.