Automatic piloting in progressive dies using medial axis transform

Abstract

Nowadays, progressive dies have a special role in various methods of sheet metal production. The design process, however requires a considerable amount of time and expertise. During the last three decades, different concepts of Computer Aided Progressive Die Design (CAPDD) have been studied all around the world. CAPDD involves various activities and among them piloting has been paid the least attention by researchers. In this paper, a mathematical model based on Medial Axis Transform (MAT) is introduced. This model is applicable to parts without suitable circular holes for direct piloting. The model analyzes the part geometry in order to find the best position for semi-direct and indirect pilots. It also optimizes the piloting system using minimum scrap strategy. A prototype software is also developed to automatically design auxiliary holes on the scrap part of the strip for piloting purposes. The input to the software is nesting template of the workpiece, which is composed of line and arc segments, and the output is the piloting system. The model is demonstrated through several industrial examples.