Automatic generation of NC cutter path from massive data points

This paper proposes methodologies and algorithms through which a three-axis NC cutter path can be directly generated from massive data points obtained with contact or non-contact measuring devices. At the beginning, a Z-map model is employed to set up mesh points in order to economize on the use of computer memory. Rough-cut paths are produced by machining volumes of material in a slice-by-slice manner: firstly cutting the raw material into several slices on the basis of depth of cut, next judging from intersection information the cut and non-cut areas, and then generating rough-cut paths of slices. Fine-cut paths are achieved by the height correction method, which by degrees examines mesh points within the cutters' projection areas. Any interference between the cutting tool and the data points is taken into account during the correction of the cutter height. Aside from a theoretical discussion, this research develops a computer-aided engraving system to prove the applicability of the proposed methods. In contrast to traditional copy milling, computer-aided engraving provides users with much more flexibility, reduces machining time, and adapts the workpiece forms to different circumstances so as to manufacture male or female dies. (C) 1998 Elsevier Science Ltd. All rights reserved.