| The Numerical control technology is one of the most important parts in modern Automatic control technology. The interpolation technology is the crucial one in NC (Numerical Control) System, it directly determine whether the numerical control system has a good market share, and interpolation algorithm is a key component of the interpolation technology. A good interpolation algorithm can not only form the outline of the parts with high precision, good surface roughness, but also save a lot of processing time, reduced processing cost The interpolation with NURBS (Nun-Uniform Rational B-Splines) curve has many advantages. It can provide uniform velocity, high efficiency and smooth surfaces. It is significant to study interpolation with NURBS curve of CNC.This paper will focus on deep research on the development, properties and related parameters of the NURBS curve, use the Hamming differential equation simplification algorithm and estimation of a correction method to control parameter calculation error, and the segmented acceleration-deceleration control method to effectively control the speed of change and the limit acceleration value, through which the problems of the existing NURBS curve interpolation algorithm such as chord error, speed and acceleration control can be solved.First we calculate the curve control points and the knot vector according to the NURBS curve construction method presented in this paper and we prepare the NC program which can be recognized by FANUC CNC system. Then we use the FANUC CNC system to process the NURBS curve according to Linear interpolation, Circular interpolation and NURBS interpolation respectively. At last the surface collator was measured with the Roughometer, and we analyze the measuring data to obtain the actual results of various interpolation methods the machining accuracy of parts.Through the comparative analysis of NURBS interpolation, we can easily find that it is a better way to ensure the machining precision and geometry accuracy, and to improve the processing quality of surface.Not only the surface of subsequent polishing workload is greatly reduced, but also the requirement of High Performance NC machining of complex surface is better met. The amount of NURBS interpolation codes is only20to50percent of that of the linear interpolation, which can greatly shorten the time of program transmission. This paper provides a new way for building surface modeling and processing, and validates the superiority of the NURBS model and NURBS interpolation tool path through experiments, which can improve the accuracy of high surface processing with path planning. |
