Optimization on the Performance of a Precision Flank-Locking Locknut Considering the Machining and Operational Parameters

Abstract

In this study, the anti-loosening characteristics of a precision flank-locking locknut fabricated under various machining processes and tested in different dynamic environments were investigated. The control parameters considered include the tightening torque and thread pitch of the set screw, machining process on the end plane of locknut, and vibration amplitude and frequency of dynamic loading in service, etc. Their sensitivities on the axial force ratio and anti-loosening ratio of the locknut were evaluated using Taguchi method. It was found that the pretension of locknut, the tightening torque and the pitch of set screw, and the machining process of the nut's end plane were the significant control parameters for the anti-loosening performance of the locknut. Moreover, the results of experimental measurements were employed in the regression fit on the performance of the locknut. The regression model was able to predict the anti-loosening ratio with 4.42% average error comparing with the measurements. Furthermore, the optimized design of the locknut through the Taguchi method was able to increase the axial force ratio and anti-loosening ratio by 20.4% and 16.8%, respectively, comparing with standard locknut.