Tubular blank design to fabricate an elbow tube by a push-bending process

The elbow push-bending process involves pushing a tube between a die and a mandrel to bend a tubular blank into an elbow shape. In this study, the yield was improved by minimizing the cutting loss at the ends of the elbow tube. This was achieved by developing an optimized method for the design of the tubular blank. The design method is based on the deformation behaviors during the push-bending process and was formulated to minimize the cutting loss. An analysis was done to develop design rules for determining the intrados and extrados lengths and the inclination angles at both ends. Given a radius of curvature and the target dimensions of an elbow tube, it is possible to provide the optimum dimensions of the tubular blank to be bent in the push-bending process. The proposed method was successfully implemented in an actual production line and showed improved dimensional accuracies with reduced cutting losses.