Geometric reasoning in feature-based design and process planning

Abstract

A new methodology for coupling design and automatic process planning based on form features is described. The approach offers a balance between the computer-aided design and manufacturing planning processes based on an object-oriented, feature-based design environment and feature refinement, a new knowledge-based approach to geometric reasoning in generative process planning. The object-oriented feature representation methodology provides an extensible platform for interactive three-dimensional design of prismatic parts with CSG-like construction, and an internal model that incorporates a hierarchical vector-based tolerance structure. The process planning system, which includes fixture planning, automatically transforms the design feature model through geometric reasoning tasks that merge, classify, sequence, and refine features into machinable cavities. The discussion includes examples from an implementation in a system for quick turnaround machining with which one-of-a-kind prismatic parts can be interactively designed, automatically process planned, and CNC machined in a matter of minutes.