The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 2nd Report, Rotating Bending Fatigue Strength of the Specimens with a Rolled V Groove

Abstract

In order to clarify the effect of rolling conditions on the fatigue strength of rolled screw threads, the V grooves were rolled on cylindrical specimens and the rotating bending fatigue tests were carried out on these specimens. For this purpose a simple rolling attachment was designed and manufactured. The rolling pressure in the case where the V grooves were rolled by this attachment, was measured. This rolling process was analysed, and compared with the process of thread rolling. In the experiment the rolling conditions of the V groove were changed by varying the number of revolutions of the specimen during rolling process. The specimen materials were medium carbon steel cold worked and Cr-Mo steel quenched and tempered. As a result it was found that the endurance limits of the specimens with a rolled V groove were 2.5∼2.8 times higher than those of the specimens with a cut V groove. Statistical analysis has shown that there exists a definite relationship between the rolling condition and the endurance limit.