Study In Prediction Of Milling Forceand Dimensions Based On Machining Simulation

As a prior method applying to the period before actual machining, Numerical Control Machining Simulation, NCMS for short, can effectively reflect the processing condition, ensure the accuracy and reliability of Numerical Control machining, which makes it have caught widely attention and application. However, both the domestic and foreign researches about NCMS mainly focus on Geometric Simulation, and pay insufficient attention on Physical Simulation. In this paper, based on Geometric Simulation and combined with the development of NCMS, the milling force prediction and the dimension prediction of simulation results are further studied. The main research contents are as follow.The first part begins with a comparison between three modeling methods in machining simulation, chooses Z-Map work piece model as a research object and completes geometry machining simulation. In this part, the characteristics of Z-Map modeling method are analyzed and user-defined modeling of virtual work-piece is completed. After this, NC program interpretation module is developed which would transfer NC program to discrete cutter location data. Finally, this part establishes NCMS environment and build the simulation of NC milling process.The second part studies the prediction method of milling force applying to ZMap model based on geometry machining simulation. For end milling machining, this part would establish instantaneous milling force model based on discrete microunit theory, then develop extraction method of cutting parameters in the course of machining simulation based on Z-Map model. Finally, instantaneous milling force prediction and average milling force prediction would be achieved.The next part improves several parts of 2D image processing algorithm aiming at putting forward a set of suitable boundary extraction method for Z-Map model. The transformation from 3D virtual model to corresponding binary image is completed at first through slicing process. On this basis, the tracking and extraction of boundary information would be completed, which need to perform boundary tracking and extraction algorithm based on backtrack judgment. Then corner points are identified by judging the curvature change of each extracted point on closed boundary chain, and primitive fitting method based on self-adaption threshold is used to process adjacent corner points to fit boundary figures of virtual work-piece precisely. After all that, this part performs dilation operation to get border dimension information of virtual model and finally dimension prediction for Z-Map model would be achieved.The final part would develop NCMS system integrated with geometry machining simulation function, the milling force prediction function and dimension prediction function. The verification results show that the modeling and algorithm milling force prediction and dimension prediction are feasible, and the module based on the above two runs normally, the prediction results of which meet the simulation requirements.