Research On The Key Technology Of Multi-axis CNC Milling For Tool Path Generation Of Dental Restoration

Along with the advance and improvement of computer technology, measured data is widely usedin reverse engineering, rapid prototyping and CNC machining. In the field of oral medicine, dentistsuse3-coordinate measuring machine to converse patients’ teeth which need to be restored into digitalmeasured data for the convenience of computer aided design and machining. Relying on the project ofnational science and technology support program, this paper accomplished some further researchconcerning the key technology of high-speed NC milling of dental restoration. The main work andresults as follows:(1) Measured data always carry typical defects, and traditional offset method cannot create thehigh quality CL-surface of mesh model with such defects. I proposed a new offset algorithm, which isfault-tolerant and intersection-free with the utilization of MLS surface fitting. Firstly, I generated anexpansion sphere model of dental restoration with the radius equivalent to the offset length. Secondly,using the computational geometry application of convex hull, I acquire the data of outermostenveloping surface of this expansion sphere model. Finally, using local MLS projection fitting method,I wipe out existing defects, and generate the high-quality CL-surface of dental restoration.(2) The sidewall surface of dental restoration manufactured by three axes CNC has poor quality.I put forward a tool path generation algorithm of multi-axis high-speed milling based on the sectionalplane method. Firstly I generate multi-axis high-speed milling CL-curve of dental restoration relyingon the sectional plane method, and then based on Arc matching method determine cutter axis vectorof the multi-axis high-speed NC milling. After that, using the offset deformation algorithm, Icompleted the interference and collision detection of finish tool path, and finally generate finish toolpath of dental restoration on the multi-axis high-speed milling using the arc connection method.(3) We realize the rear processing module containing the coordinate transformation and machinelanguage translation of the Wieland T1multi-axis high-speed milling center for the dental restorationbased on its structural parameter. Implementing virtual simulation about the dental restoration ofmulti-axis NC milling machining in the VERICUT virtual simulation platform, this article putsforward a result evaluation method of high speed milling technology with optimization of the highspeed milling parameters of dental restoration.