Programmed in this thesis is an interactive graphics procedure which generates cutter location data (CL-data) for the machining of extrusion die (actually the electrode) on an NC machine.
Input data describing the surface of extrusion die are provided as a set of points on the die surface which should be shrunk to make the surface of the electrode used to machine the die by EDM (electrical-discharge machining) as is the usual case. The output of the program is a CL-date file which is to be "post-processed" off line in order to produce an NC tape.
The surface of extrusion die is a general sculptured surface, and is easily fitted as a composite Ferguson surface. However, care must be taken to minimize fitting errors. For this purpose, the magnitude and direction of each tangent vector are carefully determined by the program.
With the aid of (interactive) graphical display, the user can plan the machining process (e.g., cutter selection, clamping, cutting direction, etc.) and confirm the result. CL-data can be generated either in parametric directions or in cartesian directions, the latter being a must if the die is to be machined on a $2\frac{1}{2}D$ NC milling machine.
