Based On Point Cloud Of The Nc Tool Path Data Generation Methods

Reverse Engineering is an important technology which is to realise the digital copying and improvement of a product part.It has very broad application prospects.The integration of RE and NC machining has become an important technical means of design and product innovation . In general procedures of RE,the tool-path of NC machining was generated from surface model which was reconstructed from measured point cloud by surface fitting,offset and trimming. .The processing of free-form surface reconstruction is greatest difficulty of RE. These methods were not only fussy but also inaccurate especially.According to this fact, we hope to find a way,which can bypass this difficulty.Though properly processing to point cloud data,we can get the NC tool path data directly.In this way, rapidity and high efficiency of RE technology can fully embody.On the base of direct processing,this subject had achieved a integrity technology roadmap from the point cloud data to the processing tool path data .The first part is how to constructive the corresponding STL model from point cloud data.The next step is several important technical aspects: reconstruction STL model topological relations, subdivision STL model, equidistant offset subdivision surface. Finally,we can get the NC tool path data through post-processing for cross-lines which is formed by the cross-sectional plane and the equidistant surface of triangular facets in the STL file.The point to this paper can bring under five main headings:(1) Quisition and preprocessing of data points, generation of the STL file;(2) Generation of the STL file by the scattered point cloud to topology reconstruction, and analyse of the data structures for the surface offset of the grid and numerical control machining;(3) To enhance the data accuracy, we have researched and imcomplmented surface subdivionsionfor the triangular mesh which is established by topology reconstruction;(4) Research and ralization of the equidistant offset of subdivision surface to avoid interference in the course of processing;(5) Getting the NC machining tool path making use of the cross-sectional plane.