MAGNETIC BEARING SPINDLE APPARATUS

摘要

A spindle 2 is formed with a cooling-working fluid channel 19 axially extending therethrough. A housing 1 has fixed to the rear end thereof a tubular cooling-working fluid supply member 29 inserted in the fluid channel 19 with a clearance formed therearound. The radial spacing between the outer peripheral surface of the supply member 29 and the spindle inner peripheral surface defining the fluid channel 19 is made greater than the radial spacing between touchdown bearings 9 and the spindle 2 as supported contactlessly. The inner peripheral surface defining the fluid channel 19 is formed, over a range extending from the rear end of the channel and greater than the depth of insertion of the supply member 29, with helical grooves 21 for sending a cooling-working fluid forward when the spindle 2 is in rotation. A working fluid reservoir 32 communicating with the clearance between the spindle 2 and the supply member 29 is formed in a rear end interior portion of the housing 1. Drain ports 33 are formed in the housing 1 in communication with the reservoir 32. A labyrinth seal 28 is formed between the housing 1 and the spindle 2 for providing a seal between the housing interior portion formed with the reservoir 32 and a portion to the front of the interior portion. Consequently, the entire spindle device is prevented from malfunctioning.