Effect of Lubrication on the Coefficient of High-strength Bolt Screw

High-strength bolts are often used in high-precision and high-precision working conditions, which have high requirements on the quality of bolt connection. This article mainly introduces the effect of lubrication on the torque coefficient of high-strength bolts.

A set of self-made devices for detecting the axial force of the bolt connection is used to measure and change the lubrication conditions of each contact surface of the bolt connection, thereby determining the optimal lubrication condition of the bolt connection, and putting forward requirements for the assembly process of high-strength bolts.

At present, there are many methods of bolt fastening and installation frequently used in the national standard and in the industry. Among them, the simplest and easy to master method is the torque method. After considering the three-dimensional effect and the influence of elastoplastic deformation (the change in friction coefficient during tightening is negligible), for certain types of connectors, as long as the torque coefficient is measured, the torque applied during the tightening process can be measured , To calculate the pre-tightening force of the bolt. The quality of the bolt connection is related to the safe operation and reliable use of the structure. Therefore, the determination of the relationship between the tightening torque and the pre-tightening force (that is, the torque coefficient) has very important engineering practical significance.

So far, the influencing factors of the torque coefficient have attracted widespread attention. On the basis of theoretical analysis, many university researchers and engineering technicians have studied various factors affecting the torque coefficient of high-strength bolts from the aspects of bolt quality and installation and inspection process. And through experiments, the influence of various factors on the torque coefficient is preliminarily studied, and reasonable suggestions are made for the manufacturing and assembly process of high-strength bolts.

Shan Changwei et al. conducted high-frequency and longitudinal vibration tests on high-strength bolts such as wheel connecting rods to study the influence of vibration on the tightening effect of bolts, and put forward more reasonable test methods and methods. Gu Qinghong et al. studied the effects of temperature, saponification solution concentration and time on the torque coefficient of high-strength bolts, and obtained some technological measures to increase the axial force.

Nassar et al. studied the influence of zinc coating thickness on bolt torque coefficient through comparative experiments. For high-strength bolts, Qiu Yuanyuan, etc., through experiments, studied the influence of minor thread damage, temperature changes, and surface conditions on the torque coefficient of the bolts and the changing law of the torque coefficient, and the tightening of high-strength bolts through the changing law of the torque coefficient Several comments were made during the process.

While studying the torque coefficient of high-strength bolts, it is also necessary to understand and control the dispersion of the torque coefficient to more accurately control the pre-tightening force of the bolt. In this paper, the influence of lubrication conditions on the torque coefficient and the change law are studied, the change law of the torque coefficient under different conditions of thread lubrication, gasket lubrication, and thread gasket lubrication in the process of bolt connection, and the determination of the bolt torque coefficient The distribution provides reference for bolt design and assembly process, so that the pre-tightening force can be precisely controlled by controlling the torque in the project.