Object-oriented approach to generative process planning for rotational parts with axisymmetric features

Abstract

Modern manufacturing industry has recognized the development and adoption of computer inteb'Taledmanufacturing (elM) technologies as an effectivc and decisive lactor to remain competitive in thc market. Computer aided proecss planning (CAPP) plays a key role for achieving elM by integrating design and manufacturing systems. But a pedect CAPP system which considers all the complex activities of process planning is yet to be developed. In this work, an object oriented approach for the design and development of CAPP system has been presented, sinec objectorientation can model complex systems efficiently. The objectives of this research arc the development of algorithms for extraction of both external and internal axisymmetric features of a rotational part. development of algorithms for the sel~1.ion of blank, operations, machine and cutting tools for the generation of process plan, the design of a system to utilize pOlential capabilities of objectoriented technology and the dcsign of a systcm for the complete integration of design and planning systems. An algorithm has been developed which can extract geometric information from thc drawing file of a rotational part and recognizes both the external and intcrnal machining features. The algorithm allows the user to exercise his freedom and creativity in modeling a part, since it sets no predefined sequencl: to follow during design process. Algorithms and production rules have becn dcveloped which can select the appropriate blank, operations, machines and cutting toob for the process plan. The integration betwecn computer aided design (CAD) and CAPP systcms is a vital issue for the complete mtegration of manutac:turingcnvironment. The system has been designed such that it ensures this integration of CAD and CAPP systems. The system takes the drawing file as the input and generates the process plan without any human involvement. The proposed system makcs effective usc of the object-oriented teelmology. The hierarchy and polymolJlhism features of the object orientation have been utilized such that future modification and evolution of the planning system can be done easily. This objeetoriented system allows effective representation of data and knowledge base used in the plmming process. So it implements databases for part, blank, machine, operations and culling tools effectively and future modilication of the databases can be done casily. The system eliminates needs for central knowledgc base and inference engine by implementing the rules in the individual objects customized for it. Thus the system provides effcctive integration between design and planning flUlctions. Jt can readily generate process plan for the rotational parts. The effectiveness of the developed system has been verified jor example rotational parts and fonnd consistent with thc real process plans.