| 摘要 |
PURPOSE:To hold a spindle rotary bearing substantially within constant temperature range by providing an air heat insulating structure between the bearing of a spindle stock and the heat generating section of a motor. CONSTITUTION:A heat insulating device 50 is provided between the front rotary bearing 15 of a spindle 12 and a motor 30. This device 50 has an annular heat insulating passage 56 formed of an annular hole 51 formed in a spindle stock housing 20 and a sealing wall plate 54 made of heat insulating material arranged at the front of the motor 30, and an air stream inlet 58 formed at one position of the housing 20 an air stream outlet 60 formed at one position opposite at approx. 180 deg. to the air stream inlet 58 at the passage 56. In this manner, since the heat generated at the motor is prevented from being transmitted to a spindle rotary bearing mechanism, the mechanism can be maintained in substantially constant temperature range always even during the rotation. |
