Research On Key Techniques Of General Geometric Simulation For Numerical Control Machining

With the progress of NC machining technology,the efficiency and accuracy of machining have been further improved,However,the structure and spatial movement of machine tools have become more complex,NC programming has become more difficult,and programming errors are easy to occur,NC machining simulation is the most effective means to verify the correctness of the program.Aiming at the problems of poor real-time performance and low precision of domestic NC simulation software,this paper makes a thorough study on some key technical problems of NC machining simulation,which effectively improves the accuracy and efficiency of NC simulation.Virtual NC machine tool is the basis of NC machining simulation.The simulation of real machine tool motion process in NC simulation is realized by virtual NC machine tool.Aiming at the complex problem of virtual machine tool modeling,a method of virtual NC machine tool modeling based on component tree structure is proposed,which simplifies the modeling process of virtual NC machine tool.Aiming at the problem that kinematics derivation of each structure machine tool should be carried out separately,the general kinematics model of NC machine tool is deduced,and the unified expression of kinematics model of the same type and different structure machine tool is realized.Geometric modeling of tool scanning volume is the key of NC machining simulation and plays an important role in material removal process in NC simulation.Aiming at the problem of high time complexity in geometric modeling of tool scanning volume,Based on envelope theory,GPU as the main hardware platform and APT tool model,this paper presents a general tool scanning volume geometric modeling algorithm with parallel computing acceleration,which achieves fast and accurate geometric modeling of various tool scanning volumes.At the same time,aiming at the problem of self-intersection in the process of geometric modeling of tool scanning volume,a solution based on equidistant operation is proposed,which effectively solves the problem of self-intersection.Boolean operation is the core problem of NC machining simulation.The material removal process in NC simulation is realized by Boolean subtraction operation between workpiece and tool scanning volume.This paper implements a Boolean operation algorithm based on STL model,and improves the efficiency and robustness of the algorithm.A fast topology reconstruction algorithm for STL model based on hash table and saturation point is proposed,which improves the efficiency of the algorithm.Based on the original algorithm,an intersection algorithm of space triangle based on dimension reduction projection processing is proposed,and various singularities are analyzed in detail,which improves the efficiency and robustness of the algorithm.The experimental analysis of the algorithm is carried out through a machining example,and the results show that the research work in this paper is correct and feasible.Finally,based on the above research work,a NC simulation prototype system is developed by using VS C++ 2010,OpenGL,and QT5.7.