| 摘要 |
There is provided a vertical lathe which, when machining gradually varying lens grooves in a mold for molding of a Fresnel lens, can change the angle of a cutting tool without positional displacement of the cutting tip, enabling high accuracy machining of the gradually varying lens grooves. The vertical lathe includes: a column; a rotary table for rotating a workpiece; a cantilevered cross rail supported by the column; a saddle movable in a horizontal direction along a guideway of the cross rail; a ram suspended from the saddle and movable vertically along a guideway of the saddle; and an inclined head mounted to the lower end of the ram and having an inclined swivel shaft for holding a cutting tool, wherein said swivel shaft is configured to swivel the cutting tool around a nose of the cutting tool as the center of swiveling.
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