Research On Octree-sphere Voxel Model–based Dynamic Partial Rendering Virtual Machining Algorithm

High-speed and complex process machining have become a trend in field ofnumerical control (NC) machining, which result that the structure of workpiece to bemachined and NC machining program become more and more complicated. So virtualmachining simulation has become necessary steps for complex parts to verify andoptimize NC machining program before physical NC machining. Simulation speed,accuracy and versatility are critical evaluating indicators of virtual machiningsimulation algorithms. But they have an influence on each other, for example, the highersimulation accuracy, the slower simulation speed and the more memory requirementtaking up.In order to enhance the simulation speed, accuracy, versatility and reduce thememory requirement of virtual machining simulation algorithm, this paper proposes amethod named octree-sphere voxel model–based dynamic partial rendering virtualmachining algorithm. Focus on the proposed method, this paper mainly studies thefollowing topics:(1) Octree-sphere voxel model–based virtual workpiece voxelization method. Tospeed up collision detection and reduce memory requirement, the presented methodreplaces the traditional cube voxel with sphere voxel, and uses octree model to achieveautomatic subdivision and voxel coding for virtual workpiece. A table look-up based6-adjacency model for any voxel is also proposed. It provides fundamental model fordynamic partial rendering virtual machining algorithm.(2) Dynamic rendering method of sphere voxel size. To ease the contradictionbetween simulation accuracy and the voxel size, this paper presents a sphere voxeldynamic rendering method. In which, When collision happens between voxel of virtualworkpiece and tool swept volume, intead of removing the whole voxel directly, the sizeof virtual workpiece voxel will be modified dynamically according to the collisionbetween voxels, so the simulation accuracy can be greatly enhanced under certain voxelsize.(3) Cutting point-based triangle mesh model for virtual workpiece. To improve therendering accuracy and efficiency of virtual workpiece surface, this paper presents acutting point-based triangle mesh model for virtual workpiece. And the sense ofimmersion for virtual machining simulation is further enhanced by illumination modesl, material models and others.Finally, an virtual milling systemt is deleopped on Windows XP operating systemusing Visual C++6.0,OpenGL as Integrated Development Environment and graphicrendering tool respectively. In this virtual milling systemt, the presented octree-spherevoxel model–based dynamic partial rendering virtual machining algorithm presented inthis paper is executed, and a numerical code interpreter is also designed. The feasibilityand efficiency of the proposed algorithm are verified.