Research On Machining Status Transformation And Material Removal Simulation Based On B-rep

In order to meet the various needs of the customs, more and more of the modern manufacturing enterprises begin to adopt the multi-type and small batch production. Along with the continuous development of computer technology and advanced manufacturing technology, machining process simulation technology came up and bas been widely used among the manufacturing enterprises. Machining simulation technology can help the enterprises to reduce the product development cycle and cost, improve productivity and competitiveness through verifying the rationality of machining process route and evaluating and optimizing the process plan. This thesis studied the machining simulation theories and simulation systems from at home and abroad, analyzed the advantages and disadvantages among different modeling methods and material removal methods. Based on the above study, the research on machining state transforming and material removal simulation for milling based on B-rep theory is proposed.As the data basis, the STEP standard is presented, the definition and architecture of STEP is described. Further more, the thesis studied the geometric structure and topological structure of the boundary representation method for solids in AP203protocol and introduced the Z-MAP modeling method for machining simulation.NC process parameters is the data driving basis for simulation prediction model and simulation for material removal process, thus a process data model for automatic programming and machining simulation system is established and its format and keywords are interpreted. The simulation system gets initialized through reading the process information into computer.The change of B-rep model is mainly in the change of its geometric structure and topological structure. The algorithm for spatial position transformation, feature deleting and feature dimension change of the B-rep model is studied using the inverse transform theory form design model to blank model on condition that the topological structure doesn’t change. Geometrical boundary intersection algorithm of polyhedral model is proposed. The system could generate the simulation prediction model which reflects the whole machining process by saving the geometrical difference of the B-rep model between different process stepsThe automatic programming algorithm for surface milling is preliminarily studied and automatic programming algorithm for smooth plan and plan with hollow inner boundaries is proposed. Local blank modeling method is proposed and the blank get discrete based on automatic programming algorithm. The tool path simulation and material removal process simulation algorithm are studied. The simulation speed is improved by proposing a optimized algorithm of searching the discrete points of the blank model.