The Influence of Corrosion on the Anti-Loosening Performance of a Precision Locknut Subjected to Rotation and Periodic Impact. (10th December 2019)

• Record Type: Journal Article
• Authors: Chen, C. M.; Chang, H. L.; Lee, C. Y.
• Is Part Of: Journal of mechanics. Volume 36:Number 3(2020)
• Page Start: 295
• Page End: 303
• Publication Date: 2019-12-10
• Subjects: Corrosion -- axial force ratio -- anti-loosening ratio -- dynamic anti-loosening tester -- precision locknut; Mechanics, Analytic -- Periodicals; Mechanics -- Periodicals; 620.1005
• DOI: 10.1017/jmech.2019.49
• Languages: English
• ISSNs: 1727-7191

Abstract

Abstract : The influence of combined corrosion and vibration to the anti-loosening performance of a precision locknut used in a machine tool is investigated. Firstly, the locknut was submerged in 5% NaCl solution according to ASTM B895 standard for corrosion testing. The locknuts, after submerged in 1-hr, 2-hr and 4-hr periods, respectively, were then installed on the rotating spindle in a vertical dynamic impact tester for performing anti-loosening test. The initial installed pretension was 9800 N and the spindle was rotating in a constant speed of 1000 rpm. Turmogrease Li 802 EP lubricant was used on the contact surface between spindle thread and locknut. The set screws on the locknut were tightened sequentially and evenly in three-stage of torque: 1.96 N-m, 3.92 N-m and 5.88 N-m. Its real-time pretension variation with the periodic transverse impact and its final loosening torque were measured. Accordingly, the axial force ratio and anti-loosening torque ratio were calculated and discussed. It was found that corrosion treatment had similar influence on both the axial force ratio and the anti-loosening torque ratio. More corrosion on the locknut with longer submersion in NaCl solution deteriorated its anti-loosening characteristics. The result could serve as the reference for evaluating the fastening performance of precision locknut and guide the design and manufacturing for the application improvement.