A 5-axis milling system based on a new G code for NURBS surface

A new NC instruction (G code) for 5-axis direct interpolation of NURBS surfaces is proposed. The mechanisms of the transferring of manufacturing information and of the processing of them are also presented. The proposed method solved the problem of the absence of the normal vectors of cutter contact points and the tangent vectors of tool path on the surfaces to be machined as a result of the approximation of the surfaces into a number of smaller straight lines and curves during the machining of NURBS surfaces, which enables CNC systems to implement the 3D online cutter compensation and the intelligent control. Mathematic model for 5-axis direct interpolation for NURBS surfaces is established, and its algorithm is programmed. Based on Windows and real-time extension for Windows (RTX), the real-time on 5-axis direct interpolation algorithm for NURBS surfaces is satisfied and the shortage of real-time of Windows is overcome. Based on above theoretical research, 5-axis system is developed. The simulation experiments of the machining of NURNS surfaces are finished, which have proved the validity of algorithm and reliability of CNC system.