軸直角振動下における各種ボルト・ナット締結体の微小ゆるみ挙動評価

Abstract

Self-loosening of threaded fasteners sometimes occurs under dynamic loads such as vibration and shock. For mechanical structures, the self-loosening with returning rotation of screw thread under transversely repeated load is particularly important. Although many parts preventing the loosening of bolt-nut joint are being evaluated the locking performance of self-loosening, there are unclear points about small loosening of bolt-nut fastener under small transverse vibration. In this paper, using bolted joint with some parts for preventing the loosening such as the plain washer, the spring washer, the conical spring washer, the toothed washer, the flange nut, the double nuts, and so on, we have examined self-loosening behavior under transverse cyclic loading. As the result, it was confirmed that the joint with double nuts is excellent for preventing the loosening. And we found that almost all the parts preventing the loosening are reduced bolt tension little by little under small transverse vibration, while the bolted joint using the spring washer and the conical spring washer is no effect of preventing the loosening under small transverse vibration.