Patent ID: 6508614
Filing Date: 2003-01-21
Classification: B23Q,F16C,G05B,Y10T

Abstract:
A spindle device with at least one combined externally pressurized gas-magnetic bearing assembly for rotatably supporting a main shaft, having a machining tool fitted to a tip thereof, and having a spindle drive source for rotating the main shaft, said at least one combined externally pressurized gas-magnetic bearing assembly comprising an externally pressurized gas bearing and a magnetic bearing combined together, said spindle device comprising:a spindle controller for controlling the at least one externally pressurized gas-magnetic bearing assembly; and an external command responsive ON-OFF means for turning energization of the magnetic bearing on and off in response to a command supplied from an outside of the spindle controller without starting or stopping the spindle drive source; an electric current detecting means for detecting an excitation current for the magnetic bearing; and a machining status determining means for determining a machining status performed by the machining tool in reference to a current value detected by the current detecting; means; wherein said machining status determining means comprises a current smoothing unit for smoothing the current value detected by the current detecting means, and a machining status determining unit for converting a smoothed output from the current smoothing unit into a static load acting on the main shaft and for determining the machining status in reference to a result of calculation of the static load.