Cutting Force Estimation Systems Based on AC Spindle Drive

Monitoring of the cutting force signals in turning process has been well emphasized for unmanned machining. Although the cutting force can be directly measured by a tool dynamometer, direct sensing in factory environment is not feasible because of high cost and limitations in setup. In this paper two indirect cutting force estimation systems are developed based on the measured output power and on the calculated input power signals, respectively. These estimation systems consider the cutting force as a disturbance input to the spindle drive and estimate the cutting force based on the inverse dynamic model. The inverse dynamic model represents the dynamic relation between the cutting force, the motor torque and the motor power. The proposed estimation systems are realized on a CNC lathe and their estimation performance is evaluated experimentally.