Virtual Assembly System Research Based On Assembly Constraints Transformation

In today’s situation of economic globalization, trade liberalization and social information, the business strategy of the manufacturing industry has undergone great changes, virtual manufacturing technology emerged as time require. Virtual assembly is an important part of the virtual manufacturing, however, relative to other parts of the virtual manufacturing, it is the weakest link. The development of virtual assembly lags behind, make the application of virtual manufacturing technology has been greatly weakened, therefore, the development of virtual assembly technology has become the main target of research in the field of virtual manufacturing technology, the resolution of this issue will enable virtual manufacturing technology to form a complete theoretical system, make production is really in efficient, high-quality, short-term, low-cost environment, but also have good service.The research of virtual assembly technology main include virtual assembly modeling, assembly process planning, assembly interference testing and assembly simulation. Product assembly modeling is an important part of design for assembly and virtual assembly technology. Product assembly modeling is the basis for collaborative assembly, complete, accurate expression of the assembly information is prerequisite for design for assembly, assembly analysis, generate the correct assembly sequence and guide the assembly simulation activities. Merit of assembly model directly impact on the efficiency of the design of following work, therefore a high level of integration, complete information on the assembly model has a great significance. As the research focus of the project application, many scholars at home and abroad has done a large number and in-depth research on the assembly model, and have achieved productive results, proposed various assembly models. Aim at the various deficiencies of the existing assembly model, in this paper, we proposed the model of assembly datum coordinate system based on constraints transformation. Through the method of assembly constraints transformation make constraints between geometry elements of parts transform to constraints between assembly datum coordinate system, thus simplifying the assembly constraint relationship between the parts.Adopt assembly relationship trees based on assembly datum coordinate system to describe assembly models of product, the amount of information of the assembly model has a high integrity, include the level of product structure, assembly relations and assembly sequence information, solved the problem of solving difficulty in assembly diagram and assembly structure tree describes the assembly rlationship is incomplete.model describes more concise, make the subsequent assembly planning more easy to realize.This article will use the three-dimensional model of the FA drive reducer, try to develop a virtual assembly system that apply the model of assembly datum coordinate system based on constraints transformation. Use Pro/ENGINEER Wildfire3.0as the three-dimensional modeling tool, build the three-dimensional model of the FA drive reducer, output OBJ graphic file. In VC++6.0programming environment, design input interface for OBJ graphic file, read three-dimensional model data fromOBJ graphics file. Introduced the OpenGL graphic standard in the system, achieve the three dimensional model geometry restructure by OpenGL, complete the interaction control operation to the three-dimensional model. Completed the mapping of the Pro/E model of the physical geometry data to virtual assembly system, complete the assembly of the FA driver reducer assembly path planning, complete the virtual assembly system of FA drive reducer.