New tandem drawing process through non-driven four roll-die and converging die

Abstract

In the past decades, drawing processes have been applied to industries worldwide by employing several new solutions. In the case of drawing using conventional dies in tandem, it is widely-known that the deliberate application of back-pull can contribute to the improvement of die life and reduction in die load. To a certain extent, back-pull is present in the drawing process because the drawing force in the preceding stand tends to act as a back-pull in the next drawing stand. In the case of drawing by using a non-driven roll-die, deformation occurs between the roller pairs without the driven rolls. The drawing process using a non-driven roll-die can lead to a decrease in friction. The drawing process using a roll-die consumes lower power in comparison with other processes, owing to the decrease of friction.In this study, a multi-roll-die drawing (MRD) process, which is a new tandem drawing process through a non-driven four roll-die and converging die, is proposed to reduce the drawing force. The MRD was evaluated by being compared with the multi-die drawing process (MDD). First, a prediction model of the drawing force based on Geleji’s equations and the cross-sectional method was used. Additionally, the contact areas of the converging die and roll-die were modified for the shape-drawing process. The drawing force of the process through two dies in tandem was evaluated by being compared with the drawing force of a conventional drawing process. Subsequently, finite element (FE) simulations were performed to predict the drawing force in each process. They were used to verify the calculated drawing forces of the MDD and MRD processes. Moreover, experiments with regard to the MDD and MRD processes were performed to verify the predicted drawing forces. The predicted results were compared with the experimental results. Thereby, it was found that the predicted drawing force was in good agreement with the experimentally measured force. The drawing force reduction in the MRD process was evaluated by being compared with that of the MDD process. To investigate the effect of each process, numerical simulations, and Vickers micro-hardness tests were conducted, and their results were compared.