Research On The Key Technology Of Virtual Simulation Evaluation System For NC Turning

The virtual simulation system of NC turning is established the virtual turning machine tool through the computer modeling technology.The use of virtual reality and visualization technology to realize simulation of NC machining process.The system integrates hardware and software in one,achieves the same operation of the actual CNC machine tool and generates the information which is equivalent to the actual processing.The development and application of virtual simulation for NC turning saves the cost of running a school,which includes the expense of CNC machine tools and an area of teaching and so on.On the other hand,it increases the practice time for the trainees to operate the lathe and improves the teaching quality and learning efficiency.The virtual simulation and evaluation system of NC turning can indicate the shortcomings in the operation of the trainees,which can improve the trainees' learning efficiency and cultivate their ability of self-learning.In this paper,the outer surface of the NC turning shaft parts is taken as the research object,and the virtual simulation eveluation system is taken as the core.The main research work is as follows:(1)The cutting parameters of the outer surface of NC turning are obtained and the cutting force model is established for virtual environment:The cutting parameters(cutting speed vc,feedrate f,cutting depth ap)in the numerical control program are acquired,and the cutting force model is established to suit the virtual simulation of the specific environment,in order to optimize the cutting parameters.(2)The dimensional information of the NC turning shaft parts in virtual simulation system is obtained and the roughness model is established:The simulation principle of virtual turning axis parts is studied,and the half-profile contour polygon of workpiece axis is cut by a tool scanning polygon.Base on OpenGL to do geometric transformation,the operator can measure the element in the world coordinate system under the polygon size.A roughness model is established to be suitable for virtual simulation of NC turning.Because of the workpiece after cutting recording the information about the cutting tool and the cutting parameters,the surfaces roughness value can be measured easily.(3)Optimization of NC turning parameters in virtual simulation system:According to different requirements of rough machining and finishing,the objective IV functions of corresponding optimization are given respectively,and the corresponding optimal results are obtained by using particle swarm optimization.(4)The evaluated weight of virtual simulation of NC turning is given by using analytic hierachy process:The evaluated target is the degree of conformity between the virtual simulation shaft parts of NC turning and the drawing shaft parts.Through the analytic hierarchy process,the weight of each evaluated parameter under the hundred percent scale is obtained.(5)Analysis of the trainees' simulation process and evaluation of the trainees'operations:Under the different conditions(not aligned with the tip point,incorrect choice of turning materials,tool selection is nor correct,the cutting parameter selection is not correct,etc.)to do the simulation of turning the workpiece,the system gives the appropriate test scores,and points out the need to improve the place for self-learning.