The Study Of Critical Technique Of Conceptual Process Planning

One analysis shows that at least 70% of the product's final costs are set by the decisions made during the design stage. This implies that once a final design is completed, there is little opportunity to reduce the product cost since a significant portion of its cost has already been determined. Base on this fact, companies strive to consider economic factors as early as possible in the design process.Lack of manufacturing knowledge among designers is considered the main cause of the current inefficient product development process. An experienced designer repeatedly chooses the manufacturing process he/she is familiar with, without considering alternative processes and material. This is harm to improvement of the technique of production. Conceptual process planning (CPP) is an activity of cost preliminary manufacturability assessment of conceptual design in the early product design stage. It aims at determining manufacturing processes, selecting resources and equipment, and estimating manufacturing costs roughly. Conceptual process planning supports product design to optimize product form, configuration, and material selection and to minimize the manufacturing cost.There are a lot of researches related to process planning of detail design including the development of various CAPP systems for machined parts. However, there has been relatively little work done in the area of CPP. Most of the present prototype system of CPP is short of the essential, efficient part information and the reasonable description of shapes and features. So this research focuses on the following specific problems:1) The significance of studying CPP is analyzed. Some important research activities that have made major contributions to the development of conceptual design and CPP are reviewed. Based on the insufficient analysis of the existing CPP, a new architecture of CPP including its information model and activity model are presented;2) The technique of extracting part and feature information based on UG solid models is studied. The interface of information extraction is established supported by the UG/Open API and Visual C++ 6.0. The required informationof CPP, such as hierarchical part data, technology and management data, are stored in the database of the part model established by SQL Server 2000;3) Investigating the validity maintenance in the feature modeling. Based on the feature recognition and design by feature to analyze the interaction between features. The feature mapping interface of CPP about manufacturing features of milling and drilling is programmed by incremental feature recognition and conversion technology;4) According to the design attributes of the part, the model's similarity of part layer is compared based on hierarchical equivalence relation. Based on the complete information of part geometry and feature, the similarity assessment interface of part geometry and feature is programmed. The outputs of the similarity assessment interface are similarity degree and compatible features. The significance of this research is not restricted in CPP. For the processplanning of detail design and CAPP, the critical technique studied in this research, such as how to extract the complete information of part from CAD models, how to realize the primary model-design models map to application models, how to carry through the similarity assessment of part models, are important to search and extraction of similar parts, similar technologies and analysis of manufacturability and cost estimation.