Research On The Techniques Of Modeling And Sequence Planning For Digital Pre-assembly

The development process of complex product needs to be supported by concurrentengineering and digital design and manufacturing technology, and it is more prominence inthe assembly design activities of product. In concurrent engineering, developersaccomplish the whole product assembly design, planning, simulation and analysis tasks bythe digital technology. During design period, design and planning problems can be foundout and solved by the application of digital pre-assembly technology in productdevelopment. Thus enterprises can win market competition by supplying product withshorter time, better quality, lower cost and better service. So it is very important to researchand apply key techniques of digital pre-assembly in theory and reality.The advanced manufacturing technology background is introduced such as concurrentengineering, digital design and manufacturing firstly. The demand of advancedmanufacturing technology is analyzed for digital pre-assembly. Then the concept of digitalpre-assembly technology is presented and its significance is expounded. For the researchoutcome of digital pre-assembly technology in national and abroad, the research status isanalyzed. Based on it, key techniques of digital pre-assemble are put out as the researchemphasis of the dissertation, such as the architecture, design and development method ofdigital pre-assembly system, assembly modeling, assembly sequence planning.By analysis of digital pre-assembly technology feature and demand, the architecture isexpounded for digital pre-assembly system. The function component, structure and workflow are researched. A system framework is constructed by four layers such as interfacelayer, applying layer, the object data layer and the technique support layer. By thearchitecture of digital pre-assembly, methods of system construction are expounded such asthe system design method of object-oriented, software development method ofcomponent-based. These techniques are expounded for digital pre-assembly environmentconstruction, such as geometry display and motion manipulation, and assembly actionresponding.On the basis of information requirement for the digital pre-assembly system, the assemblymodeling method is expounded by three dimensions architecture. By the layered andmulti-views and variation particle modeling strategy, three views are constructed for theintegrated assembly model of product. They are hierarchy view, attributions view, andrelation view. The information expression, gaining, saving and matching are researched for three directions views of assembly model. The technique is put forward for the dynamicgaining the assembly relation information based on the set theory. Then the information isundertaken for the digital pre-assembly process in concurrent engineering.The principle of assembly sequence planning is researched arid put forward based on theassembly sequence SAP tree. The assembly sequence SAP tree model is constructed whichinvolves relation node and data node. The assembly sequence SAP tree can express thenonlinear assembly sequence and concurrent assembly task effectively. By the methodwhich is based on geometry reasoning and knowledge reasoning, the assembly base part isconcluded and the general sub-assembly is identified. Then the product function structuretree is transformed to the product assembly structure tree, and the assembly sequence SAPtree is created based on the product assembly structure tree. Because considering someprocess restrictions in the assembly sequence SAP tree, the calculation extension ofassembly sequence is reduced. The comparative assembly prior relation is ascertained asthe synthetic target of assembly sequence evaluation. The index architecture of assemblysequence evaluation is established. Weights of all evaluation indexes are calculated usingthe entropy method. By searching the assembly sequence SAP tree according to thepriority in its width, the fuzzy synthetic evaluation and optimization of assembly sequenceis finished using two stages and layers. The evaluation and optimization efficieney ofassembly sequence is heightened.A digital pre-assembly prototype system of product is developed by these methods andtechniques in this dissertation. It is illustrated by a product of multi-direction transmissionand upholding. In the digital pre-assembly system, these tasks are accomplished such asassembly design, analysis and verification of assembly design, assembly modeling,matching and dynamic gaining of the assembly model information, assembly sequenceplanning et al. These key techniques are illustrated by the implementation of the digitalpre-assembly prototype system and its application for instance in this dissertation.