Constraint based modeling of automatic shape generation processes

Automatic shape generation using advanced numerical control techniques is based largely on product modeling. Novel models involve constraints to separate the results of earlier decisions in product design from parameters that is free to modify for the subsequent stages of the product design process. The paper describes a research that is aimed to analyze other groups of constraints that restrict changes in product model from the side of manufacturing process, production and production system. This requires appropriate modeling of manufacturing processes and production systems then relating models of products, manufacturing processes and production systems. The authors consider design of mechanical parts as a continuous engineering process to improve the design. Accordingly, they developed a manufacturing process modeling approach and methodology that is suitable for continuous modification of the part manufacturing process on the basis of messages about modification of the part model. Equally important but in this paper less discussed problem is modification of the manufacturing process model on the basis of changing demands from production scheduling. The method is based on generic manufacturing models that involve variants. Entities in this model are represented by Petri nets that are repeatedly executed when a modification of the part model initiates it. The manufacturing process is modeled by features and the method assumes a reorderable form feature based part model. The paper is organized as follows. Firstly, background and objectives of the research are introduced. Related problems of present day part and manufacturing process modeling are outlined and the concept of integrated modeling is emphasized. Following this the proposed integrated modeling approach and methodology are detailed. Next issues of implementation of the proposed modeling are discussed. Finally, possible contribution to enhancement of modeling capabilities in present day CAD/CAM technology is concluded.