Cylindrical-shaped workpiece evaluation method and evaluation apparatus

A cylindrical-shaped workpiece evaluation apparatus comprising:

• storage means for storing a plurality of two-dimensional reference shape data based on a two-dimensional shape displayed on a two-dimensional plane where a curved surface of a reference cylindrical-shaped workpiece is developed;
• designation means for designating one two-dimensional reference shape data read from said storage means based on the two-dimensional shape;
• conversion means for converting the reference cylindrical-shaped workpiece having a curved surface having a two-dimensional shape corresponding to the two-dimensional shape data read from said storage means into a surface shape of said reference cylindrical-shaped workpiece;
• calculation means for measuring a surface shape of an evaluation object cylindrical-shaped workpiece and obtaining a distance between a measurement point in said measurement and a point in the surface shape of the reference cylindrical-shaped workpiece converted at said second step, corresponding to said measurement point;
• display control means for overlay-displaying the distance obtained by said calculation means as an error on the two-dimensional shape corresponding to the two-dimensional reference shape data read from said storage means,
• wherein the evaluation object cylindrical-shaped workpiece is evaluated based on the two-dimensional display where the error is overlay-displayed.

A cylindrical-shaped workpiece evaluation method comprising the steps of:

• designating a two-dimensional shape representing a curved surface of a reference cylindrical-shaped workpiece;
• obtaining a surface function of a cylindrical shape in the reference cylindrical-shaped workpiece;
• converting the surface function of the cylindrical shape into a three-dimensional surface shape of said reference cylindrical-shaped workpiece;
• measuring a three-dimensional surface shape of an evaluation object cylindrical-shaped workpiece;
• obtaining a distance between a measurement point in said measurement and a point in the surface shape of the reference cylindrical-shaped workpiece, corresponding to said measurement point;
• and
• calculating an error by comparison between the three-dimensional surface shape of reference cylindrical-shaped workpiece and the three-dimensional measurement data;
• converting surface function of cylindrical shape in reference cylindrical-shaped workpiece into a two-dimensional function;
• and
• generating two-dimensional data;
• and
• displaying calculated error based on two-dimensional data.