飞机快卸锁锁紧螺母重复使用特性

Characteristics of Prevailing Torque Nuts in Aircraft Latches Under Repeated Uses

用于固定飞机表面快卸口盖的锁紧螺母在重复使用过程中容易发生松弛,使其拧出力矩减小,锁紧功能失效。首先从材料应变硬化、低周疲劳、接触面摩擦系数等方面对锁紧螺母最大拧出力矩的变化规律进行了定性分析。材料确定后,收口值的大小成为影响锁紧螺母重复使用特性的主要因素。试验研究中选定了3种不同收口值的锁紧螺母进行拧入拧出的重复使用试验,测量它们的最大拧出力矩。试验结果表明,随着重复使用次数的增加,螺母最大拧出力矩最初有一定波动,经历一段(N<200)恢复上升后,在重复使用次数200<N<1 500范围内,又缓慢下降趋于稳定;收口值对最大拧出力矩的下降速率有较大影响;获得了具有稳定符合规定最大拧出力矩的最优收口参数值。

Prevailing torque nuts are widely used to fix the quick release covers on aircraft surfaces, But the unscrew torque decreases and locking mechanism may fail with repeated uses of the nuts. Parameters that may affect the maximum unscrew torque are first qualitatively analyzed which takes into consideration material strain hardening, low-cycle fatigue and frictional changes. The slotting gap value is considered to be a significant parameter that affects the repeated use characteristics when nuts of a specific material are fixed, and experiments are carried out to study it. Nuts with 3 different designed slotting gap values are screwed in and out to simulate the multiple reuses. The maximum unscrew torques are measured and torque-reuse curves are obtained. The test results show that, with the increase of reuse times, the maximum unscrew torque fluctuated at first, and, after a certain degree of recovery （a period of 50-~N-~200）, decreased again slowly to a steady state during the region of 200~N^1 500, The slotting gap value affected the decrease rate and the best slotting gap value is obtained from the three tested designs.