Research On Collision Detection And Precision Verification In The CNC Machining Simulation

With the continuous development of advanced manufacturing, virtual machining simulation technology become a hot topic in the field of computer-aided design and manufacturing technology, many scholars have done lots of research in this field for years, in the virtual environment of CNC machining simulation, the collision detection technology and precision verification technology are classical problems, which has attracted much attention. moreover, the technology of mechanical manufacturing is growing rapidly today, in order to meet the requirements of processing complex surfaces in space, CNC machining systems also will be more complex, making the complexity of processing environment in virtual simulation system increased quickly, no doubt, it has a new higher requirements for collision detection technology and precision verification technology. Based on the user realistic requirements for simulation system of CNC machining, as well as the practical significance of collision detection and precision verification in the simulation system, the author have done in-depth research in the work of designing and implementation of the algorithm, and achieved the main function of the module.For graphical environment of 3D CNC machining, make use of the powerful OpenGL graphics library, to develop a strong sense of reality virtual machining environment, and use STL format data to describe space geometry objects model to achieve a realistic graphical environment, analyze multi-axis CNC machine coordinate system, achieve universal coordinate transformation from coordinate of each motion axis to the global coordinate, establishing a universal virtual multi-axis machine coordinate system, build a prototype of virtual NC machine tools, combined with NC code module, control the spatial movement of the virtual multi-axis machine tool.For collision detection module, at first, research and analysis the algorithms of collision detection which commonly used today, and then based on the characteristics of that more refined model of discrete tool, use OBB bounding box to build the Box-Tree of tool, use AABB bounding box to build Box-Tree of STL models of machine parts, use separating axis method to detect collisions between the box tree, to achieve a rough collision detection, which as soon as possible to exclude the majority of geometric objects which impossible collide, in order to coordinate the accuracy and speed of the rough collision detection; then for the bounding box which collided, based on the intersection of geometric elements(triangular facets) to achieve precise detection, to achieve accurate collision detection of all of the simulation geometry between objects in simulation system, ensure collision detection system with high precision.For accuracy verification module, at first, research and analysis the accuracy test algorithms which commonly used today, and according to the way that the virtual machining simulation system use discrete surface model, based on the accuracy test methods of existing that, cutting errors based on discrete points, proposed a precision cutting error detection method based on discrete triangular facets, calculate cutting errors of discrete surface that to determine the accuracy of the cutting errors, which can be more practical approach of cutting errors.