A new CNC tool path planning method is developed for accurate and efficient finishing cutting of sculptured surfaces. The proposed method generates CNC tool paths based on an offset surface of an object instead of the actual surface. The new algorithm consists of two main computationaltechniques:offset surface generation techniqueand offsetCNC tool path planning technique.In offset surfacegeneration. approximate parametric offset surfaces are generated accurately from an original parametric surface by employing bi-cubic surface patch, surface conversion. and surface subdivision algorithms. In offset CNC tool path planning, the precise geometric models of chordal deviation and cusp height on an offset surface are established. The effectiveness of this proposed CNC tool path planning method is verified by geometric simulation and verification which detect and identify errors in CNC tool paths.

This paper presents a new measuring strategy that can be used to inspect the quality of sculptured surfaces. For dimensional inspection of sculptured surfaces, one important issue is how to compensate the alignment error because the alignment of sculptured surface leads to significant problems. The key aspect of the method is to use probe approach direction in the Z-direction (that is, an arbitrary or uniform direction) of CAD surfaces, in constructing the measured surface, in order not to be effected by alignment error. In the proposed method, the offset surface concept is introduced to eliminate normal directional error. The method uses the probe center points instead of its surface contact points as measured data for localization. Then the surface points are calculated from the localized measured data and surface normal vectors of the offset surface. For the new measuring strategy, a practical offset surface generation algorithm and localization algorithm are developed. A measuring experiment has been performed for a sculptured surface to show the effectiveness of the proposed method.