UNFOLDING SHEET-METAL PARTS - A GRAPH-BASED APPROACH

In sheet metal fabrication, bending is used in order to obtain rigidit y and to obtain a part of desired shape and function. In analysing a s heet metal part, an important consideration is how to unfold the part after a bending operation or series of bending operations. The unfoldi ng process is the first major step in process planning for generating NC paths for a sheet metal blank. This paper addresses the problem of determining whether or not a part can be unfolded. A graph-based appro ach using the face-edge of the sheet metal part is at the heart of the algorithm presented here. Using this algorithm one can determine whic h faces are unfoldable and which cannot be unfolded. This algorithm ca n be used to help facilitate the process of NC path generation. It als o sheds some light on the kind of design practices that make a part ea sily unfoldable or otherwise.