Speed-dependent tool tip compliance measurement of a high-speed machine tool spindle using an active magnetic bearing (AMB)

In this paper, we proposed a new measuring method of the speed-dependent tool tip compliance of a highspeed machine tool spindle using an AMB (active magnetic bearing). Single sine wave current excitation is injected through the AMB, and the displacement and force responses are measured with a CCS (cylindrical capacitance sensor) and a dynamometer, respectively. Then, the tool tip compliance can be estimated accurately without any phase delay by dividing the frequency response from the current to the displacement by that from the current to the force. A flexure test rig was designed to represent dynamics of a machine tool spindle and the feasibility of the proposed measuring method was proven experimentally comparing with the impulse test. Finally, the tool tip compliance of a high-speed machine tool spindle was measured successfully using the proposed measuring method.