Super-Finishing Tool Path Generation for Digitized Models Supported by Super-Finishing Form Feature Recognition

Abstract

Abstract The realization of sculptured shapes using CAD systems is still today a very complex and time consuming operation. For these reasons, design by physical modeling is still in use and remains in force in many industries (automotive, ski boots, sport articles). For the manufacturing of complex free-form surfaces, in situations in which it is more desirable to proceed from a physical model to a numerical definition rather than use mathematics to derive the physical part, copy milling techniques are widely used. This paper gives a brief overview about copy milling techniques for 3 axis copy milling machines, and proposes a feature based method to support an automatic tool path generation for the super-finishing phase. The proposed method is divided in two parts: super-finishing features recognition and tool path generation. Using copy milling techniques, the model of the object to be milled is obtained by digitizing. Therefore a global mathematical surface description of the model does not exist. In such a situation a model interpretation phase is required to recognize the super-finishing features and thus proceed to the tool path generation. A two step algorithm for super-finishing feature recognition on a digitized model is proposed: features arc recognized on the basis of the digitized point density and the normal vectors of the triangles generated by the surface reconstruction (based on Delaunay triangulation method). The tool path is then generated using a method based on the calculation of the Voronoi diagram on the area identified as super-finishing feature. The super-finishing feature recognition and tool path generation modules have been integrated as part of a more general CAM system for copy milling called HICAM. The architecture of such a system will be presented together with examples of solutions obtained by means of the use of the implemented prototype modules.