Analysis of double nut installation technology based on new anti loosening performance evaluation test method

This paper analyzed the torque combination mode of double nut installation, and two common installation methods are tested and verified by using a new anti loosening performance evaluation method. This method can evaluate the anti loosening performance of small size bolts below M5. Through the test, it is found that when the installation torque of upper and lower nuts is different, the anti-loosening performance of double nuts is better than that of upper and lower nuts with the same mounting torque. It is found that there is a certain dispersion in the anti-loosening performance of double nuts, It is analyzed that the reason for this phenomenon is the difference of product quality. It is proposed to evaluate the quality consistency of fastener products through the dispersion degree of torque coefficient K, and a method to determine the installation torque through the angle torque curve is given.