| 摘要 |
PROBLEM TO BE SOLVED: To always maintain the floated variable of a floating ring constant in both cases of the normal rotation of a surface plate and the reverse rotation thereof by forming a dynamic pressure generating groove, which applies the floating power by the hydraulic pressure to a rotating floating ring, symmetrically in relation to the normal and reverse rotation of the floating ring. SOLUTION: When a floating ring 23 is rotated in one way, the lubricating oil 22 enters between an upper surface of a sliding member 24 and a lower surface of a floating ring 23 along a rotating directional inclined surface 26a of a dynamic pressure generating groove 26, and the floating ring 23 is floated by the work of the hydraulic pressure, and a lower surface plate 12 is rotated in the contact-less condition that it is supported by the hydraulic pressure. Vibration in the vertical direction of the lower surface plate is thereby restricted, and the surface plate is stably rotated without generating vibration. Even in the case where the surface plate is rotated in the reverse direction, since the forming pattern of the dynamic pressure generating groove 26 is the same with that of the normal rotation, floated variable of the floating ring 23 becomes the same with the case of the normal rotation, and generation of difference of polishing rate between the normal rotating direction and the reverse rotating direction is eliminated. |
