| 摘要 |
PROBLEM TO BE SOLVED: To accurately and symmetrically form a curved surface of a long size upper end surface by vertically moving a shaving blade to a tangent of a circular arc formed of an arc-shaped rail, and reciprocating an edge so as to abut to the long size upper end surface. SOLUTION: A mask frame 4 is fixed to a pedestal 8. A shaving blade lifting part 10 is moved up to one end of a long size upper end surface 2 of the mask frame 4. A shaving blade 32 is lowered on a vertical straight line so that an edge 33 is allowed to abut to a lower position cuttable from the corner of one end of an upper end surface 2. A work arm 17 is circularly moved with the center of a circle formed of a circular arc so that both corners of the long size upper end surface 2 is cut in a round shape in the same shape as an arc- shaped rail 16 by the edge 33 of the shaving blade 32. Then, the work arm 17 is inversely circularly moved to be returned up to one end of the long size upper end surface 2 to lower the shaving blade 32 so that both corner parts of the long size upper end surface 2 are cut further in a round shape in the same shape as the arc-shaped rail 16. This operation is repeated to be cut in the same shape as a circular arc of the arc-shaped rail 16 toward the center from both end sides of the long size upper end surface 2.
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