Visual comparison of multiple tonnage signatures by using snake skeleton graph

This paper presents a new method to represent the tonnage signatures from the sheet metal stamping operations. First, the new method, called the snake skeleton graph, is introduced. It uses Bézier surface to model the instantaneous stamping force distribution and hence, can capture the three-dimensional spatial features of the tonnage signatures, such as the imbalance of the transient forces. These features have clear physical meaning and can be used for diagnosing the stamping operations. Based on the study of two practical examples, a failure map is developed that can be used in shop floor applications.