Tool path generating device and hairline machining system

A tool path generating device generating a tool path for machining hairline-shaped long narrow grooves extending in one direction on a workpiece surface, comprising:

• a shape data acquisition part acquiring shape data of a workpiece;
• a parameter setting part setting a shape parameter of a hairline corresponding to the long narrow grooves, the hairline having ranges in which the hairline passes above a reference tool path and ranges in which the hairline passes under the reference tool path;
• and
• a path generating part generating a reference tool path, comprising a plurality of connected tool paths extending in the one direction and arranged in rows, for generating a surface in the workpiece based on the shape data acquired by the shape data acquisition part and adding to the reference tool path a vertical feature of a shape of the hairline relative to the surface of the workpiece, based on the shape parameter set by the parameter setting part, so that discrete long narrow grooves, along the tool paths, are formed in the surface of the workpiece by machining the surface of the workpiece within the ranges in which the hairline passes under the reference tool path, whereby transforming the reference tool path into a tool path for a hairline machining.