| 摘要 |
PURPOSE:To maintain a stable polishing function for a long period by providing a key operating means for displacing a movable key to a position sunk from the fitting position when an upper surface plate is lowered to fit a rotatable member in a drive member. CONSTITUTION:When compressed air is supplied to a chamber 21 by an electro- magnetic valve 26 before an upper surface plate unit 1 is lowered, a key 8 retreats against the urging force of a spring 10 so that the front end 8a is placed lower than the peripheral surface of bore of a case 3. Then, said unit 1 is lowered by a lift mechanism 4 to fit the case 3 in a drive member 6 and stop the case in a key aligning position. Thereafter, a chamber 21 is opened to the atmosphere by said value 26. Then, the front end 8a of key 8 is protruded by the urging force of spring 10 so that the drive member 6 is slowly rotated to make phase coincide and engageably springs into a key way. Thus the movable key 8 does neither collide with the drive member 6, nor incline, but securely fits so that the upper surface plate 2 is securely driven and the stable polishing function can be maintained for a long period. |
