Five Spline The Whole Process Of Application Technology In Cnc Machining

Spline function is a very useful mathematical tool which is extensively applied to Computer Aided Design (CAD), Computer Aided Manufacturing (CAM), Computer Numerical Control (CNC) and Reverse Engineering (RE), and so on. With the developing of technology of high speed cutting (HSC), man attaches more and more importance to the application of splines in the HSC of freeform surfaces. And spline technology is more and more developed and more widely applied, and becomes one of important trends of NC machining technology. In this dissertation, the algorithms of quintic spline interpolation and their applications in CNC, NC programming and RE are researched in detailed, and the whole theory, methodology and technology of quintic splines are founded. Furthermore, the STEP-NC-based CNC system with open architecture is investigated elementarily. The key issues studied and important conclusions deduced in the dissertation are as follows:(1) The status quo of study and application of spline technology, especially the problems in the HSC of freeform surfaces and the tendencies of CNC technology, are analyzed summarily. Compared with cubic splines, quintic splines have more advantages for surface machining. So the generation and processing of NC instructions have become one of the nucleal technologies of CAM and CNC.(2) Although spline curves are applied widely, but the research on the algorithms of quintic spline interpolation is little. Therefore, some algorithms of quintic spline interpolation are first developed or improved, tested and evaluated. The algorithm of local quintic spline interpolation (QA3) and quintic B-spline interpolation (QA4) therein are very propitious to curve fitting of discrete data points and to NC programming of freeform curves and surfaces. From the viewpoint of real-time calculation, the QA3 is fitter to the geometry processing and real-time interpolation, because it is local and calculates simpler and faster. The systemic research on the algorithms and the correlative algorithms establish massive foundation for the application of quintic spline curves in NC machining.(3) Until now, interpolation points have mostly been selected manually in an empirical way. It is necessary to explore methods to find out interpolation points for processing of substantive and dense digitized data in an automatic manner. This dissertation presents two algorithms called as "quintic-curve-method" and "sixtic-curve-method" which are applied to automatically select nodes for quintic spline interpolation. The proposed algorithms are proved to be robust and effective in the spline interpolation due to always getting satisfying results, namely less number of nodes and more rational distribution within desired tolerances. In addition, the"cubic-curve-method" and "quartic-curve-method" are also developed for cubic spline interpolation. These algorithms are of great significance for digitized data processing, and supply a gap in spline interpolation.(4) To develop spline-based real-time interpolation for curves or surfaces is an essential approach that can solve the problem and suit the individual needs of HSC of freeform surfaces. Based on the analysis of characteristics, quintic splines are considered as the best spline functions that can commendably satisfy the requirements of HSC of surfaces. So the generation and processing of quintic spline-based NC instructions, which includes the generating process of NC instructions, processing of geometrical data, feed control and real-time interpolation, are investigated, and the theory, method and technique are systemically founded.(5) Reverse Engineering-oriented CNC systems are superior to normal CNC systems of which the RE software is independent. Therefore a PC-based, Reverse Engineering-oriented CNC system is implemented and its architecture and function model are described. By investigating the application of quintic spline in digitized data processing and NC...