| 摘要 |
PROBLEM TO BE SOLVED: To ensure an easy and sure surface shape control at low cost by disposing a plurality of grinding portions coming in contact with a specified surface of a workpiece so as to be changeable in their positions within the working surface. SOLUTION: This surface plate 2 is of a disc like metal member type and has a working area excluding a recessed part 5 at the center thereof. A pressure plate 6 is horizontally supported above the surface plate 2 while being set off from the center of the plate 2, and a specified surface of a workpiece W1 is fixed to a lower surface of the plate with the surface directed downward. Polishing pellet holding holes 7 are formed in the working area of the working surface 2a so that cylindrical polishing pellets 3 can be inserted thereinto or removed therefrom. To finish the specified surface of the workpiece W1 into a round shape with its center projecting, the pellets 3 are densely arranged toward the rotation center area, while to finish it into a round shape with its certer recessed they are roughly arranged. Accordingly, the cutting-in speed to the specified surface of the workpiece W1 changes by the sliding contact between the pellets 3 and the specified surface to ensure a required specified surface. Accordingly, a highly accurate round surface can be easily and surely obtained. |
