S1104-1-4 Self-Loosening Performance of Prevailing Torque Type Nuts under Repeated Tensile Loads : on the Thread Calking Type Nuts

Abstract

Recently, the prevailing torque type nuts have been widely developed and used in bolted joints for preventing self-loosening. Thus, the standards on prevailing torque type nuts have been specified in JIS. However, only few researches have been reported on the loosening mechanism of the prevailing torque type nuts under repeated tensile loads. The effects of the anti-loosening is not elucidated. In this paper, experiments were carried out to measure the self-loosening of bolted joints with four types prevailing torque-type-nuts under repeated tensile loads. As the result, the bolted joint using the biggest nut shows the best performance for preventing the self-loosening compared with the bolted joints using thread calking type of the nut of which the deformation is the biggest, moderate and smaller.