The Research Of The Five-axis Double NURBS Curve Interpolation Algorithm

With the rapid development of economy, China has become the second manufacturer and exporter in the world, but not a manufacture power. An important factor restricting our country to be a manufacture power, is the Five-axis CNC technology, which is an urgent demand of important strategic equipment in civilian industry and military industry, such as marine, aviation, mold, high precision instruments and so on. The Five-axis CNC technology is the most difficult technology for the multi axis CNC, and also the most widely used one. The interpolation algorithm is the core of the multi axis CNC system, and also is the foundation of CNC system. Five-axis interpolation algorithm has gradually become a key research topic for researchers around the world. The technology is blockaded by the developed countries and CNC companies all the time, which impedes the development of chinese five-axis CNC technology. In order to break the blockade, we must research the Five-axis CNC technology independently. Therefor, studying the Five-axis double NURBS curve interpolation algorithm and its realization mode is full of great significance.At present, the main traditional interpolation algorithms (linear, circular interpolation) can’t meet the modern high speed and high precision machining requirements more and more.Based on the CNC machining research, we find that the key factors to restrict high speed and high precision machining is the interpolation algorithm. NURBS curve can express the free-form curve and surface, and analytic curve and surface by uniform. Based on the fact that NURBS curve directly interpolation technology can avoid traditional interpolation algorithm for many problems, it can effectively solve the contradictory between the interpolation algorithm and modern high speed and high precision machining. For Five-axis CNC machining of double NURBS curve interpolation method by increasing a cutter location spline, is in favor of cutter axis vector information representation and extraction. On the basis of considering the chord error and acceleration or deceleration processing, we use two order Taylor expansion to solute node parameters, then can get the axial feed increment quickly and accurately. In this paper,through UG/GRIP secondary development language to write the source code and to use UG to generate the tool path, and then depending on post builder of the tool path source file,we can build the double NURBS curve spline code. Through analysis of the double NURBS spline interpolation procedures examples, it is proved to be advantageous than the traditional method, which can effectively improve the machining efficiency and precision, and meet the requirement of the interpolation operation for the high speed and high precision machining of the complex curved surface parts.It can creat the condition of maximizing the modern high performance CNC fine characteristics, and play a positive role in promoting our level of CNC system.