Sensor-less cutting torque monitoring for a high speed spindle applying disturbance observer

High speed milling is a practically feasible operation to improve the cutting accuracy and efficiency. On the other hand, large heat generation and progress of tool wear are serious problems. In order to modify the cutting condition properly, the machining state should be evaluated according to the process information such as cutting torque. This paper presents sensor-less cutting torque estimation method for a high speed spindle with hall sensors, applying disturbance observer. Instantaneous speed observer and interpolation method are employed to estimate the cutting torque with high accuracy. The validity of the presented method is verified through a time-domain simulation, and the feasibility is experimentally evaluated by comparing the proposed estimation and measurement with a torque dynamometer.