抄録
In the tip test based on backward extrusion, the distance of the radial tip from the external side surface of the workpiece deformed has a linear relationship with the maximum forming load measured. In this study, finite element analyses were carried out to calibrate the relationship between this radial tip distance and the shear friction factor. It has been found that this relationship is in linear such that the simple measurement of this radial tip distance can be used to effectively predict the shear friction factor. Also, the friction conditions at the punch and lower die were examined. It was found that the shear friction factor at the lower die is about 60 and 75% of the one at the punch with and without a centering groove used, respectively. However, the predicted values of shear friction factors were similar regardless of the type of centering groove used.
