A FEATURE RECOGNITION AND EXTRACTION METHOD USED TO DEVELOP A CAPP MODEL FOR “L-BLOCK” FAMILY OF PARTS

A Computer Aided Design (CAD) model system represents designed parts as a volume. This type of representation is not usable for most manufacturing programs even for Computer Aided Process Planning (CAPP). The volumes of material that are necessary to remove from a stock material represent the geometric features. These features have to be recognized and extracted from the CAD data. Being an important task that bridge CAD and CAPP, feature recognition provided greatest contribution to fully automated CAPP system development. An approach for feature recognition is based on boundary representation (B-Rep). Data is collected from a STEP file provided by the CAD system and is compared with the predefined variant of the feature. This paper describes the development of a CAPP model specific for a family of parts whose preprocessor have the role to extract the information from neutral format file and to settle it for recognizing process. The recognizing process is using a rule-based algorithm. The output of the preprocessor is the feature data such as dimensions, coordinates and spatial position relative to the XYZ axis system. CAPP system mainly replaces this information in a predefined machining sequence with variables.