Design of novel dies for gradually forming threads of high-strength screw

A novel dies for thread rolling were newly designed to extend life of die. Most of thread rolling dies have tapered and complete thread inlet and outlet in the fixed one but has no tapered on the moving one. Rolling process of conventional dies and newly designed ones was simulated by using commercial FEM code DEFORM (v.13.0). Simulated results were compared with results of experimental trials, and are good agreement with experimental trials. Stresses of novel dies were smaller than those of conventional ones. It should be extend the life of rolling die by using newly designed ones. And strain gauges were not attached on threads but on side. Even if the location of measured stress is on side, the measured stress distribution is good agreement with simulated ones. It would be useful to surmise the stresses of threads.