Research On Cutting Simulation And Evaluation Of Virtual CNC Machining System

With the rapid development of economy, the types of CNC machine tools are growing increasingly and updating frequently. But CNC machine tools are still expensive. Lack of funds and sites, a school can’t get new types of CNC machine tools or have a great number of CNC machine tools, which makes a great limit in teaching and training. To solve this problem, this paper adopts CNC machining simulation technology, analyzes description methods, real time drawing algorithm and storage format for CNC workpiece models, analyzes collision detection algorithm during the cutting, and analyzes the evaluation methods for processing results. Based on the research, this paper developed a virtual CNC simulation prototype system. The detailed research contents in this paper are in the following:Studies on description methods, real-time drawing algorithm and storage format for workpiece models. Considering the parametric size requirements and cutting demands, this paper adopts vertex grid model to describe workpiece models. As to the model drawings, based on the normal drawing algorithm, we propose a self-accelerating drawing algorithm which based on the triangular facets in vertex grid of workpiece. By increasing the drawing area of a single triangular facets and reducing the number of facets required to be drawn, it realizes to accelerate the models drawing. Then, describe the models storage by using XML format.Studies on collision detection algorithm during the cutting. First, specify the principles and procedures in3D modeling, describe the structure division and overall assembly, and give the obtaining method and space conversion method for models. Then, describe modeling requirements, parameter and bounding box of cutting zone for3D models. Finally, discuss the relationship between the internal space coordinate system and their coordinate system conversion for the machine. And give detailed description for bounding box collision detection algorithm which based on the cutting area.Studies on the evaluation methods for processing results. In order to improve the learner’s learning and self-inspection, make them compare their processing results with the standard processing results, this paper proposes an evaluation method based on feature extraction. It is based on fixed-point data of the workpiece models. First, we create hierarchy diagram for workpiece models. Then, get the key specifications of each structure. Finally, do the feature-based computing by the correspondence among the hierarchy of the workpiece models, and realize the equality evaluation judgment for the processing results. As to the different workpiece models of milling machine and lathe machine, we give different weight value for evaluation criterion.Developed a virtual CNC simulation prototype system, by using Visual Studio2010and XNA Game Studio4.0. The system realizes workpiece cutting simulation and its processing results evaluation and so on. Based on the prototype system, we verify the self-accelerating drawing algorithm, cutting algorithm and evaluation method by experiments. The experimental results show that self-accelerating drawing algorithm proposed on this paper can achieve fast and real-time drawing requirements, cutting algorithm can complete the right processing procedures, and evaluation method can give available correspondence evaluation.