Intelligent speed-increasing spindle using traction drive

An intelligent speed-increasing spindle using a wedge-roller-traction drive (WTD) is developed to realize high-accuracy milling. The WTD is a type of planetary roller variator, whose ring and sun rollers are nonconcentric. The generation of little heat is a feature of the WTD. Some cutting tests were carried out, and the measured surface roughness of the WTD spindle was found to be better than that of a commercially available speed-increasing spindle using planetary gears. Moreover, the function of measuring cutting torque during end milling was added to make the spindle intelligent. The countertorque at the carrier is measured using a piezofilm. Measurement and calibration procedures were proposed and their effectiveness was confirmed by experiments.