The Research On CNC Interpolation Algorithm For Complex Curves And Surfaces And Its Development Of Self-programming System

The curve surface interpolation module, which is the core of the whole numerical control system software. The choice of interpolation arithmetic directly affects the machining speed and the accuracy of CNC system. It is one of the exactly improve and perfect portion of numerical technology. In order to endow CNC machine tools with the function of directly machining complex curves and surfaces, relevant theoretical researches and practical experiment about curve and surface interpolation algorithm were made in this paper.Since 1991, NURBS was defined as the only way to free curves and surfaces by the international standardization organization (ISO) in the promulgation of the STEP standard, the method of using NURBS to express complex curves and surfaces was widely applied. At the same time, NURBS curves and surfaces real-time interpolation technology has become a hot topic of the research on numerical control interpolation technology in recent years. Accordingly, the NURBS curves and surfaces interpolation function has become a symbol of the contemporary high-performance CNC system functions. In this paper, the mathematical module of NURBS curves and surfaces was researched deeply and a specific process interpolation algorithm of NURBS curves and surfaces was also given. In the course of a linear approximation for NURBS curves approach, a new method was proposed, which is extendable-step method. On this basis, the real-time interpolation algorithm and specific examples of NURBS curve were given. Not only the chord error but also the machine acceleration (the change of velocity) was considered in the researches process of NURBS curves real-time interpolation. On this basis, the method of flexibly structuring acceleration and deceleration control by using the trigonometric function was proposed firstly in this paper. This method assures placidly change of velocity, acceleration and jerk velocity. Simultaneously, the algorithm is simple and its project usability is good.In this paper, the preliminary researches on complex surfaces (NURBS) direct interpolation technology were made. The basic ideas and module structures of complex surface direct interpolation technology were also explained. In the process of NURBS surface direct interpolation, the real-time tool paths have studied deeply and the specific algorithm for real-time tool path was given.Finally, in this paper, the numerical control self-programming software was researched on the basis researching on direct interpolation technology of complicated curves and surfaces (NURBS). There are three parts in this software system, which includes former processor, main processor and post processor. And the former two parts were mainly studied in this thesis.