Study And Development Of The Modular Fixture Virtual Assembly Experimental System

During teaching of modular fixture assembly design experiments, the element number is so large in the modular fixture element library that students can hardly find the right elements soon to finish the assembly of fixture. To solve this problem, this thesis developed the computer-aided modular fixture virtual assembly experimental system FixAssem.The aim of the FixAssem system is to integrate all contents in the research field of Computer-Aided Fixture Design(CAFD) which can be realized in softwares into UG NX. Consequently, on top of modular fixture element library and workpart case library, this thesis planned and set up the whole framework of FixAssem in Visual C++ 6.0 environment, which is maked up of four subsystems, interactive assembly(I-CAFD), design verification(CAFDV), case-based reasoning(CBR), web-based assembly.Modular fixture element library is the basis of the whole modular fixture design system, and its element number is the key fact to determine whether the modular fixture variant design is convenient. Since element number of the element library is often large, a special element library constructing tool for FixAssem is needed to be developed. On the basis of object-oriented method, this thesis combined NX Open C API, NX Open Menuscript and NX Open UIStyler to develop a modular fixture element library constructing tool(about 10000 lines of code written), and then established a small modular fixture element library.To improve the element library constructing efficiency and simplify user input, the individual information of a modular fixture element is plotted as a whole 6-layered structure, the top 3 layers were realized in the menu and the bottom 3 layers were realized in the dialogs. At the same time, some character pointer arrays were defined to integrate all the contolling parameters and information, nesting switch statements were used to realize the bottom 3 layers' controlling and elements' modelling.Compared with many existing standard part library constructing tools, this element library constructing tool has friendly interface, all its codes have blocking structure, and it's independent of database, so it can execute efficiently and occupies little disk space. This element library constructing tool can apply to modular fixture in modular fixture experiment teaching, and its application can also be extended to other electromechanical systems as the library constructing template.