Research On The Tool Path Planning For5-axis NC Machining Of Complicated Triangular Mesh Model

Compared with3-axis NC machining technology,5-axis NC machiningtechnology has incomparable advantages. Hence it has become one of mainmachining methods of complicated surface. Triangular mesh model has been widelyapplied in many fields, such as rapid prototyping manufacturing and reverseengineering. And there are significant progresses for3-axis NC machining oftriangular mesh model. However, the research for5-axis NC machining ofcomplicated triangular mesh model is insufficient. And the main difficulties whichexisted in the study are how to increase the efficiency of global interference detection,to guarantee the smooth and steady tool orientation, and to generate tool path for5-axis NC machining of complicated triangular mesh model. In order to solve suchproblems as the global interference detection and avoidance, tool orientationoptimization, and tool path planning for5-axis NC machining of complicatedtriangular mesh model, the researches were launched on the base of the establishmentof the topological structure and the calculation of the differential geometry data. Themain work was as follows:Firstly, a rapid global interference detection method was researched. An efficientmodel searching structure was established based on K-D tree and tool limited discreterepresentation. And a quick global interference detection and avoidance algorithmwas proposed. The interference point was searched by model searching structure. Theefficiency of global interference detection was improved by speeding up the modelsearching.Secondly, the method of tool orientation optimization was studied. To avoid thedramatic change of adjacent tool orientation and the unduly large angle between toolorientation and machine spindle, a tool orientation optimization strategy of angledarea was presented based on existing methods. The adjacent tool orientation on sametool path was optimized and the tool orientation relative to machine spindle wascorrected by the strategy, which smoothed and steadied the tool orientation. Finally, according to the characteristic of complicated triangular mesh model and5-axis NC machining, the method on projective and offset was modified. A methodon iso-scallop tool path planning for5-aixs NC machining of triangular mesh modelwas put forward. In this method, the offset model of cutter contact point wasestablished based on normal vector. Then the cutter contact tool path was smoothedby eliminating the deficiencies, such as fold line, undulated path, path redundancyand self-cross.Based on above research achievement, the tool path planning program for5-axisNC machining of complicated triangular mesh model was developed, and the runningexamples verified the feasibility of aforementioned algorithms.The innovations of the paper are as follows:1. An efficient model searching structure is established. Then a rapid globalinterference detection and avoidance algorithm is presented which improve theefficiency of global interference detection.2. A tool orientation optimization strategy of angled region is proposed, whichsmooth and steady the tool orientation.3. A method on projective and offset is modified, which solve the offset problemof cutter contact point on the mesh surface.4. A quick self-cross judge approach is provided based on K-D tree and themethod of projective and intersection.