Research And Development Of Manufacturing Process Simulation Based On STEP 3D Surface Model

With the development of manufacture technology,the pattern of multi-variety and small batches has became the main pattern of manufacture.For reducing the manufacture cost,shortenning the manufacture cycle,getting the best project of design and technics,the simulation technology of manufacturing process has been mentioned and widely used in some factories.In this thesis, present domestic and overseas research situation of modeling and material removing method for manufacturing process simulation is investigated roundly and their deficiencies are analyzed.According to this situation,the research and development of manufacturing process simulation based on the model of the standard for the exchange of product model data (STEP) is proposed.STEP documents is analyzed and the structure and geometrical entity description method is studied.Entities described in EXPRESS are mapped into corresponding classes in C++.Geometrical information from STEP documents is extracted and stored into C++ memory.The character of modeling and basic setting method of OpenGL(Open Graphics Library) is introduced.The boundary description method of 3D model based on OpenGL is described.Geometrical features in STEP are analyzed, the construction geometrical information of surface model is builded based on the structure of STEP.The 3D surface model is reconstructed for OpenGL drawing.The disperse method for faces of surface model is studied.The disperse method for arcs and the triangulation algorithm for cylinders are designed in detail.The meshed model is drawn by OpenGL functions in 3D environment.The surface model of tool swept volume for simple manufacturing method is constructed based on process parameters.A material removal method based on intersection algorithm between surface model of tool swept volume and parts is described.The changing rule in the method of the part surface model is studied,and the schedular the method is designed in detail.The mapping algorithm from geometrical Feature to process feature is described to offer essential data to CAE/CAM technology based on process features. On the basis of the previous research,a 3D simulation of manufacturing process based on the surface model of STEP documents is developed by object oriented C++ language and OpenGL graphic library in VC++6.0 development environment in Windows operate system.It could solve the difficulties in modeling and enhance universality in simulation program by the STEP documents. The material removal method based on intersection between surface model of tool swept volume and parts is described to offer a directly rule of judging the design and technics.