A New Bending Force Formula for the V-Die Bending Process

The V-die bending force is an important parameter in respect of press machine capacity selection, but it has not been the focus of previous research. Furthermore, while the various modified formulas proposed in previous research were calculated using V-die bending theory, they are insufficient for predicting the actual V-die bending force. Based on the actual V-die bending mechanism, a new V-die bending force formula is proposed in this study, in which bending is generated not only in the bending allowance zone but also on the legs next to the bending allowance zone. Therefore, the bending force in these zones must be carefully considered. The finite element method (FEM) was used as an effective technique to clearly determine the actual V-die bending mechanism and to modify and develop a new V-die bending force formula. Laboratory experiments were carried out to validate the FEM simulation results as well as to confirm the accuracy of the proposed new V-die bending force formula. Two types of workpiece material, aluminum AA1100-O (JIS) and medium carbon-steel sheet-grade SPCC (JIS), were used as test materials. The results clearly show that the new V-die bending force formula offers more accuracy in V-die bending force prediction than predictions based on past formulas. The error in the V-die bending forces predicted using the new formula was approximately 5% compared with those of the experimental works.