A maglev Local Actuator for High Speed Electrical Discharge Machining

This paper reports on a compact, 5-degrees-of-freedom (5-DOF) controlled maglev local actuator (MLA) for realizing high speed electrical discharge machining (EDM), comprising a magnetic coupling mechanism (MCM) to feed a discharge current to an electrode attached to a spindle, and to transmit a torque from a motor to the spindle. The spindle is supported by a 5-DOF controlled magnetic bearing and is rotated by following the rotation of a power supply ring, utilizing the magnetic coupling. Flexible wires between the power supply ring and the spindle feed the discharge current to the electrode, without transmitting disturbing forces, so that the spindle is free from the direct contact with brushes, used to feed the discharge current. Experimental positioning results show a prototype MLA possesses a positioning resolution of a few microns and several ten micro-radians, bandwidths greater than 100 Hz in the 5-DOF directions, and a positioning stroke of 2mm in the thrust direction. Moreover, the discharge current can be fed to the electrode attached to the spindle, rotating at 2,000min.