転造条件が転造ねじの疲れ強さに及ぼす影響 : 第3報, 転造Vみぞ付試験片の回転曲げ疲れ強さ, 続報

抄録

In the first report the published papers on the fatigue strength of rolled screw threads were reviewed, and it was reported that the fatigue strength of rolled screw threads might be affected by the rolling condition. Then the process of thread rolling was analysed theoretically. In the second report the results of the rotating bending fatigue tests on the specimens with rolled V groove were presented. In this experiment the rolling conditions of V groove were changed by varying the number of revolutions of specimen during rolling process. The type of rolling pressure curve was held constant. In this third report the results of the fatigue tests similar to those in the second report are presented. In this experiment the type of rolling pressure curve as well as the number of revolutions of specimen is varied. When the rolling is performed by the usual method using the rolling attachment reported in the second report, the rolling pressure curve becomes an increasing pressure type. Using the same attachment the constant pressure type can be obtained by a simple additional operation. In these two types of rolling pressure curves the V groove is rolled at the three levels of the number of revolutions of specimen. The fatigue tests are carried out on these specimens. The fatigue strength of the specimen with rolled V groove increases with the decrease of the number of revolutions of specimen, and is higher in the constant pressure type than in the increasing pressure type.