Manufacturing Feature Mapping and Precedence Relation Generation for Automated Feature-Based Process Planning

摘要

The common approaches that link computer-aided design (CAD) and computer-aided process planning (CAPP) systems are feature model conversion and feature recognition. The initial in the integration of CAD and CAPP systems involves the transfer of design information, which is usually expressed in terms of features. Feature-based CAD systems use design features for part, while CAPP systems manufacturing features in order to perform process planning. Additionally, CAPP systems may require precedence relations between features for process sequence generation. In this paper, we present a prototype system that automatically retrieves design information from a CAD part and generates manufacturing features with precedence relationships. The general sequence of procedures is: retrieve design information, generate equivalent manufacturing features using feature mapping, analyze geometry to determine interacting features, and generate precedence relations between the complete set of interacting features in the part. In feature mapping, the design features are mapped into equivalent machining features in such a way that the manufacturability is ensured. Interactions between features are identified based on face neighborhood relations and volumetric interactions. Interacting features are analyzed to deduce precedence relationship, which defines which feature needs to be machined before the other. Procedures for the identification and analysis of feature interactions for deducing feature precedence constraints are explained. Details of the prototype tool that performs the complete cycle of extracting design information from CAD model to the generation of feature precedence constraints are provided. The various modules of this system are developed using platform independent applications and allow for operation over a distributed environment. The reported system is expected to serve as a tool for the integration of design and manufacturing planning activities.