| 摘要 |
PURPOSE:To prevent the generation of a scratch on the specular machining face of a workpiece by fixedly supporting plural workpieces of a low hardness and dummies of a high hardness on the bottom side of a vertically movable work holder in a regular order along a circumference centering around its vertical axis. CONSTITUTION:A surface plate 15 and a work holder 20 are rotated, workpieces W and dummies D which are supported by the work holder 20 are floated up due to relative movement between the work holder 20 and a machining reference face 16 to carry out the specular machining of the workpiece W with a machining liquid 14 which is made flow between the workpiece W and the machining reference face 16. In this case, the machining face of the workpiece W with low hardness is excessively machined more than the bottom face of the dummy D is, producing a step (e) between the machining face of the workpiece W and the bottom face of the dummy D. Accordingly, after machining is advanced to a certain extent producing the step (e), even if an abnormal external force is applied, the bottom face Da of the dummy D is brought into contact with the machining reference face 16 without bringing the machining face Wa of the workpiece W into contact with the machining reference face 16 due to the step (e). As a result, a scratch is not produced on the specular machining face of the workpiece W. |
