Prediction of shear length in blanking process by numerical simulation

Abstract

Blanking process is very efficient because it can be processed at once by using a press machine. Therefore, the blanking process is used in wide range of fields. The cutting surface of the blanking process is composed of sag, shear surface, fracture surface. The sag and fracture surface may be problem in products. Thus, it is important to suppress the occurrence of sag and fracture surface. To suppress them, even if many dies are proposed, they cannot be tried in terms of time and cost. Owing to this background, the prediction of cutting surface by numerical method such as finite element method (FEM) is useful. In the previous studies, blanking process analyses were carried out in several materials, process conditions and ductile fracture criteria and the cutting surface that coincided well with the experimental result was obtained. However, it is necessary to investigate whether this prediction method of the cutting surface can be applied to other materials and processing conditions. In this study, the prediction of shear length was carried out by using the critical fracture value in ductile fracture criteria proposed by Cockcroft and Latham and Ayada in the blank element at the tip of the punch. The results show that Ayada fracture criterion is more applicable to predict the shear length under the current condition than that of Cockcroft and Latham fracture criterion.