| 摘要 |
PURPOSE:To maintain the vibrating direction of a main shaft due to an O-ring in the prescribed direction by deflecting the center of an O-ring slot in the prescribed amount with respect to the center of a bearing holding portion. CONSTITUTION:The center b of an O-ring slot formed in a bearing holding portion 12a is deflected in the prescribed amount in the direction of an arrow E with respect to the center line of a motor. Accordingly, an O-ring 9 inserted into the O-ring slot is contacted at a pressing point P with the outer race of a bearing 7 to apply a pressing force in the direction of an arrow E. Bearing supporting points S1, S2 are provided at the positions formed at an acute angle (alpha) elevationally with respect to the direction of the arrow E, and the periphery forms an escape 12c. Therefore, since the outer race of the bearing 7 is supported by the three points of the point P and S1, S2, the vibrating direction of a main shaft 5 is correctly held in the direction of the arrow E. |
