In the test, the balancing torque of the tightening torque applied by the operator to the fastener can be decomposed into / bolt) the torque Mf generated by the friction between the nut pair of the nut 0, the friction between the nut and the bearing surface of the connected member The generated moment Mr and the moment Me of the fastener due to the torsional elastic deformation. That is, the tightening torque: M=Mf+Mr+Me, all three moments are positively related to the axial tensile force F generated by the fastener, and any change in torque will cause a change in F, and vice versa. Under a certain F action state, Mf and Mr depend on the surface state of the thread contact pair and the connected member, and Me depends on the stiffness and torsional deformation of the locking system. Among the three influencing factors, the surface state of the thread contact pair and the connected member is relatively stable when the test piece is not replaced and is not reinstalled, and only the torsional elastic deformation amount of the locking system is under impact or other external conditions. It will quickly become smaller, making F smaller and the system slack. At the same time, the locking system also creeps under the action of the torque, which is also the reason for making F smaller. Therefore, the smaller the torsional deformation of the locking system and the creep of the locking system under the external force are the main reasons for the rapid decrease of the F in the /0 segment and the severe relaxation in the initial stage after the locking. The practical significance of the study of the three relaxation curves is that the study of the fastener relaxation phenomenon or the relaxation curve has the same special significance as the fastener locking research. The significance of the 1/0-segment relaxation curve study is that after the fastener is installed, the elastic deformation will be reduced and creep rapidly under the influence of the external environment, which will reduce the axial tensile force of the fastener and reduce the lock of the fastener. Tight effect. However, the tendency to reduce the amount of torsional deformation and the creep under external force are the inherent physical properties of the locking system. As long as the conditions are met, the amount of elastic deformation becomes small and creep occurs. As a conditional stress balance system, the thread locking system has a strong elastic deformation amount or recovery and creep tendency, and it is inevitable to relax rapidly under the influence of vibration or other environmental conditions. This seems to have little to do with everyday life, but the impact on defense and high-tech industrial products such as aerospace can be fatal. Imagine that if the spacecraft is lifted off, the connection of its gyro platform bolts may affect the elastic deformation stress and creep stress of the platform reference. If it is lifted off, the bolt will occur under the action of strong impact vibration or space environment. Elastic deformation recovery and creep, resulting in a reduction in axial tensile force; since the stress relief of the connecting bolts cannot be synchronized, the asynchronous stress changes of the different connecting bolts will amplify the stress distribution and deformation of the gyro platform, which will result in Deviation of the platform reference affects the serious consequences of the life of the spacecraft. Similarly, the slackening effect of the fastener locking system will also have an adverse effect on the important joints of the carrier rocket and the like. The significance of the 1/ò0 segment relaxation curve study selects and installs fasteners. We all hope that the locking performance is good and can maintain a good locking state for a long time. The /ò0 segment slack curve image accurately reflects the locking characteristics of the fastener. Through experiments, according to the length of the /ò0 segment relaxation curve, we can choose fasteners with longer locking time and better locking performance; we can also test and select better fastener materials, surface treatment methods and installation processes. . Conclusion In summary, the analysis of the relaxation curve of the thread locking system, the relaxation phenomenon of the thread locking system, and the relaxation law are very necessary. Tungsten Copper Sheet,Wolfram Copper Sheet,Wcu Sheet Tungsten,CNC Machine Tools Co., Ltd. , http://www.nstungsten.com
Brief Analysis and Discussion on the Decomposition Line of Thread Standard Parts