Research On Tool Path Generation And Optimization Algorithm In Grinding Machining Of Denture

With the continuous improvement of people ’ s living standards,dental medical treatment,as an important way to improve the quality of life,is paid more attention.Although the technology of prosthodontics is frequently updated,people’s growing demand for dental medical treatment cannot be satisfied.In the past decade,digital prosthodontics technology has gradually become the mainstream of modern prosthodontics technology.Although many overseas companies have perfect digital prosthodontics systems,their core algorithms are regarded as commercial secrets,which makes us unable to optimize the algorithm on this basis and also causes the domestic high-end prosthodontics market to be monopolized overseas.For the purpose of developing independent CAM software for dental medical treatment and improving the accuracy and efficiency of tool path calculation algorithm,this paper studies the key algorithms of grinding tool path generation and optimization in digital dental restoration.In the Qt development environment,the main functional modules of CAM software for dental restoration are developed using C + + language.Finally,the correctness and feasibility of the algorithms and software are proved by numerical control grinding experiments.The specific research contents are as follows :An improved half-edge topology data structure is proposed to reconstruct the triangular mesh.Compared with the traditional algorithm,the topology efficiency can be greatly improved.The method of estimating vertex normal vectors based on shape correction is used to supplement the normal vector information for triangular mesh.According to the principle of least squares,the mesh surface is fitted with local parabolic surface,and the curvature information is supplemented.The traditional cutting plane method and iso-parametric method are improved to make them more efficient in the tool path generation of complex structures of oral prosthesis.The rough machining tool path for molar crown is generated by the improved cutting plane method,and the finish tool path is generated by the improved iso-parametric method.Four types of defects in the initial trajectory are analyzed and summarized,which are trajectory redundancy,trajectory self-intersection,trajectory Z-folding and trajectory interference.The causes of each defect type and the influence of the defect on CNC machining are explained.The trajectory optimization algorithm that can remove the defects is given,and the continuous rough/finish tool path can be obtained.The problems,such as feed fluctuation,overcut,undercut in CNC machining,can be effectively reduced.The cutter location points obtained by tool path planning algorithms are transformed into NC code by post processing.Then,in the Qt development environment,the main function modules of prosthodontics CAM software are developed by using C + +language.The core mathematical algorithm of trajectory planning is realized in the computer,and the rationality of the tool path can be preliminarily verified through the model display module.Finally,the grinding experiment of denture was carried out,which proved the correctness and feasibility of the trajectory planning algorithm.