Research On STL Model Visualization And Tool Path Planning In Denture Machining

With the progress and development of society,the demand for denture is increasing.However,at present,most of the denture processing enterprises use foreign denture processing software.For enterprises,the high fee is bound to increase the processing cost,and can not quickly respond to customer demand.Therefore,according to the technology involved in the process of denture processing and the needs of an enterprise customer,this thesis studies the STL denture file visualization technology,denture processing pretreatment and tool path planning algorithm.On this basis,a set of denture processing model visualization and tool path planning system is developed.In order to realize the visualization of the denture model,this thesis studies the visualization technology of STL file.The format of STL file and its principles are analyzed,and the visualization of STL file is realized by container storage and corresponding algorithm.The topology reconstruction of STL file is carried out by using half edge data structure,and the redundant vertex information is removed.According to the data structure characteristics of STL file,the algorithm of STL file splicing and segmentation is proposed,which provides a technical support for adding connecting rod to the denture.Aiming at the problem of denture preprocessing,the characteristics of the denture machining trajectory are analyzed.The abnormal points in the original trajectory are merged or eliminated.By determining and solving the breakpoints,the initial trajectory is divided into straight line segment and curve segment,and the classification conditions and mathematical model of seven-section S-type speed control are given.A tool path point recognition and correction algorithm is proposed to identify and correct the "Z" type bad points,sharp points and large straight lines in the original tool path trajectory,and the correction effect is verified by simulation.In this thesis,the nonlinear error of five-axis CNC denture machine tool is analyzed and the correction scheme is given.On the basis of the above research,this thesis designs the overall scheme of the software system according to the characteristics and requirements of the denture processing.In Py Charm environment,Qt is used to design the interface.The program is written to realize the visualization of STL file,and the functions of the visual interactive operation of the denture model and the addition of connecting rod are further realized.The STL file is processed by layers,and Open CV is used to extract the contour of each layer of image,to realize the tool path trajectory planning,and further generate the NC file of CNC denture machining.The tool path trajectory of the output NC file is simulated by CIMCO software,and the effectiveness of the proposed algorithm and the developed software system is verified.