Research On Generated System For Dynamic Technology Process Based On Machine Resource And Cost Constraint

Computer aided process planning (CAPP) is the linkage between design and manufacture in the course of software integration and data share among CAD/CAPP/CAM/PDM/ERP etc.. But the application and research of CAPP is very slow. The traditional CAPP system has become a bottleneck in the integration of CAD/CAPP/CAM. Therefore, it's necessary to study and develop a new kind of CAPP system.The thesis aims at automatic-achieving several technology processes by semi-generated technology planning, and optimizing the technology processes in accordance with the proposed evaluating rules to get the best technology process. And the key technology to reach the aims is researched. A generated system for dynamic technology process based on machine resource and cost constraint has been developed on the base of WIT-CAPP.The general structure model of generated-system for CAPP is built, which is composed of the input of part information, the knowledge database of process planning, and process decision and reasoning module. The geometry features on rotating parts and other kinds of parts are described with the proposed orientation and feature description method. The information model of part technology process is designed, and the rules are raised to classify the primary shape feature and the secondary shape feature. The layer structure model of shape feature and data structure is established. The shape feature is described by the combination of feature mark and feature code method. The system fact information database and technology rule database are designed, which are suitable for the changing manufacture environment. The feature number of working procedure, i.e. the length of feature operation chain, is studied, and the data structure model of single feature operation chain is designed. The reasioning strategy and mothed, and the solution to the conflict arised in the course of reasoning is studied. The forward reasoning strategy based on rules is adopted, the rule confliction is resolved with the preference rule. The reasoning course of technology process strategy is decomposed with subordinate aim and space separation matching method. The dynamic technologyprocesses are generated with a series of reasoning process. The decision-making model of technology based on rules and reasoning is built, whose merits are that the technology decision-making rules, technology data and reasoning program is independent each other. The series-parallel connection chart is designed to describe the multipule technology processes, and the evaluating rules and function for optimizing technology process are also designed. The system is operating with a real part example. The study result of the thesis is of theoretical and practical singnificance to promote the development and application of CAPP technology.