Interactive Graphics-Based NC Programming Software Development Research

Modern CAD systems widely adopt NURBS(non-uniform rational B-spline) as the main modeling entity because they can represent other commonly used parametric curves and surfaces, while also being able to precisely present the natural quadric shapes such as cones and cylinders. Because of the protection of intellectual property, no references about the application to commercial CAD systems based on the method can be found. In this case, in order to develop a NC programming software applicable to the small business enterprise in our country, a method applied in a CAD/CAM system based on a unified mathematical form NURBS offered is proposed in the thesis. Besides, based on OpenGL graphics packages and Visual C++ programming language, two-dimensional drawing module, which includes two-dimensional drafting, edit function and aid drawing function etc., is developed in the software. Until now, all interactive design schemes proposed can be classified into two categories. One is the control point based method, which manipulates curves and surfaces by controlling the DOF (degrees of freedom) defining them. And the other is the so-called direct manipulation method. According to this method, selected points on a curve or a surface are moved to new user-defined locations. In the curve and surface modules of this system B-splines curves and Bezier surfaces are manipulated by moving their control points to new user defined locations. And for NURBS curves, the extra degree of freedom called weights is used to manipulate the shape ofcurves or surfaces.In the thesis, the preliminary research and development are made in the generation of NC codes for outline machining and output of NC codes text file.