Shape error evaluation method of free-form surface

摘要

PROBLEM TO BE SOLVED: To obtain a method for evaluating an entire form error of a free curved surface which can objectively and readily compare the entire form of an original curved surface of CAD data, etc., and a changed curved surface after molded and its difference (error), can evaluate the entire form of a free curved surface without being affected by local 'creases' or 'shrinkage cracks', can decrease influences due to a measurement error and can apply even both on a parametric curved surface and a point group. ;SOLUTION: A. An original curved surface S is divided into six curved surface units at a maximum by combination of signs (+, 0, -) of main curvatures (κ1, κ2) at each point on the curved surface. B. A changed curved surface S' corresponds to the original curved surface S, and is divided into curved surface units having the same boundary. C. Average normal vectors are acquired in each curved surface unit in the original curved surface and changed curved surface. D. A 'warp component' and a 'twist component' in all combinations for a different curved surface unit are acquired in the original curved surface and changed curved surface. E. A difference between the 'warp component' and 'twist component' in each combination in the original curved surface and the 'warp component' and 'twist component' in each of the same combinations in the changed curved surface is calculated.;COPYRIGHT: (C)2000,JPO