Fundamental Research On The Optimization Of Process Planning For The Complicated Components

Process planning optimization is the significant means of reasonable arrangement for the manufacturing process of the products, shortening product development cycles, reducing costs and improving product quality. Process planning optimization is a problem which has not yet been well solved in digital design and manufacturing as well as in quantitative CAPP. The paper is based on the existing CAPP research and process planning optimization study, some in-depth discussion in some of the basic and common problems on the process planning optimization of complex parts have been launched. Mathematical model for optimization at all stages of the process planning, from machining operation selection, set-up planning and datumn decision-making, process routing, manufacturing resource allocation, is established for the process planning optimization of the complex parts.First of all, the research on the methodology of the selection for the feature machining operation has been done, the main factors and basic principles which affect the decision-making of the machining operation selection have been analyzed, and the subjection degree function of fuzzy mapping between feature properties factors and the alternative processing collection has been defined; So a fuzzy reasoning mathematical model for machining operation election for a feature is put forward.The decision-making process is implemented through the synthesis of fuzzy relationships, the issues of resource pre-configuration for each machining feature and the corresponding realization have been discussed.Secondly, the research on the methodology of set-up and location datum selection for the part features has been done thoroughly, then the location datum selection based on fuzzy comprehensive evaluation method is proposed considering the characteristics of tolerance relations. In order to improve the efficiency of the decision-making, firstly, based on the the TAD and tolerance relations of the features, the processing features of a part are classified into a number of set-ups in accordance with the principle of ensuring the tolerance requirements, and then the location datum for each group feature set is determined following the corresponding process principles and reasoning process; The fuzzy comprehensive evaluation mathematical model and the related reasoning process of the location datum selection optimization are established, the implementation of the process is discussed in detail.Then, the problem of the process route optimization is analyzed on the basis of the above work, and the corresponding mathematical model is put forward; A hybrid GA-SA algorithm has been developed to solve the process route optimization problem.A process constraint directed graph model is established to solve the problem and a corresponding graph search technology in graph theory is embedded into the main frame of the hybrid algorithm,then a effective methodology of process planning optimization for the complicated part is proposed based on the graph theory and GA-SA hybrid algorithm.The optimization can adjust dynamically according to the actual manufacturing resource conditions in the plant, and the mechanisms can guarantee producing multiple optimal process routes.A hierarchical model of the manufacturing resources is put forward, the consistency description and classification of the properties relationships and linkages among resources on the shop floor by using object-oriented technology and E-R approach is developed, the link between the manufacturing resources and processing information is established by the standardize way, then the database logical model of manufacturing resources is obtained and a manufacturing resource information management subsystem is developed.Combined with the previously research work and achievements, the actual processing plant is treated as the application environment, a prototype system for process planning and optimization is designed and developed. The prototype system is integrated with3D CAD commercial software and based on the three-dimensional model, the3D design models of the product can be used directly to carry out the process planning design.Finally, the researehes in the dissertation are summarized and some future research direction has been presented.