Identification of multiple feature representations by volume decompositionfor 2.5-dimensional components

Decomposition of computer-aided design models into features that can be dir ectly manufactured and easily translated from one representation to another has been recognized as a necessity for robust automated process planning s ystems. The algorithms presented here vivid multiple representations of fea tures that can be used to generate plans that are easily and efficiently ma nufacturable by milling processes. Features are recognized from the faces o f a prismatic stock by first identifying missing regions on the external fa ces of the stock and then recursively descending into the part. Each missin g region corresponds to a feature. As the projection of the feature is swep t into the part changes in the cross-section are identified. These denote t he beginning of new features which become children of the original feature. This process yields a set of six trees, each of which resembles a depth-fi rst search tree and is a partial ordering of features within a setup. Multi ple representations are investigated for those features that are accessible from more than one direction. Corresponding features in the different tree s are linked by arcs, thus yielding a feature graph. The feature graph can then be used to generate optimal features for machining depending on design or manufacturing requirements such as fixtures, tolerances, corner radii, and tool accessibility.