A sensorless approach for tool fracture detection in milling by integrating multi-axial servo information

This paper proposes a sensorless approach for realtime tool fracture detection in milling by means of servo information. Cutting force and torque can be estimated in a wide-frequency range by applying disturbance observer to the ballscrew-driven stages and the spindle controllers. By integrating the estimated information in each axis, a fracture-induced variation in cutting force and torque can be accurately captured with parallel sliding Fourier transform which is an analytical approach of low computation load in time-frequency domain. Validation of the proposed method is presented through milling tests of various milling conditions with several fractured endmills.