Extraction of compound volumetric features from a three-dimensional wire frame model

Abstract

This paper reports feature extraction strategy adopted in a computer aided process planning (CAPP) system developed for prismatic parts. Automatic extraction of compound volumetric features from three-dimensional wire frame models created in AutoCAD is discussed. Size, location and shape elements of a feature are used to recognize simple volumetric features like slots, steps, holes and pockets of different profile geometries by considering a hole as a basic feature. Compound volumetric features are defined as a combination of more than one simple volumetric feature such as slot-in-slot, slot-in-step, etc. Connectivity through common surface(s)/edges between member features is used to recognize compound features. The feature extractor output can be used for the generation of manufacturing instructions, namely set-up planning, process selection, sequence generation, machining parameters selection, etc. The unique feature of this system is that it works on a wire frame model of the part and needs no help from the user in extracting features. The working of the system and algorithms used for feature extraction are explained with examples.