| 摘要 |
PURPOSE:To set a relative position between a workpiece and a tool with high accuracy by water-cooling a gas bearing portion and cooling a rotary shaft by exhaust gas from the gas bearing portion so as to improve the working accuracy. CONSTITUTION:A rotary shaft 32 is supported in a floating manner by journal bearing throttle portions 26, 27, 28, 29 and thrust bearing throttle portions 30, 31. Since the distance between a diamond blade 34 and the thrust bearing portion is very short, generation of heat at a motor portion yields a little change in the position of the diamond blade 34. In order to further reduce such a change, a stator 36 is water-cooled and at the same time, most of exhaust of pressure gas supplied to a bearing clearance from each bearing throttle portion 26-31 is converged on an exhaust hole 38, exclusive of a part thereof, so as to air-cool the motor portion through a space between the stator 36 and a rotor 37. |
