Cutter interference (or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Developed in this thesis is an algorithmic procedure for cutter interference handling that converts CC-data(Cut ter contact data; pairs of point and unit normal vector) into interference-free CL-data(cutter location data). Relevant algorithms and data structures are described in detail.
The Interference handling procedure consists of the following steps :
(a) A polyhedron model is constructed from the input CC-data;
(b) Interference 'sources' are identified from local properties of CC-data;
(c) Interference regions are completely identified based on global tests for neighboring points of the interference sources;
(d) Cutter paths are reconstructed after removing the CC-data in interference regions, while avoiding any new interferences;
(e) Interference-free CC-data are converted into CL-data to ascertain the requirements of given process plans.
The time complexity of the algorithm is O(N) when the number of CC-points N is increased by increasing the surface area (with fixed density of CC-points), and it becomes $O(N^2)$ if N is increased by the density of CC-points (with surface area fixed).
The algorithm works on CC-data which could come from any type of surface models, and as a result, it can be used as an 'offline' post-processor in producing interference-free CL-data. A prototype interference handling system has been implemented in FORTRAN 77 on an IBM PC/AT.
