Analysis of the reasons for the loosening of high-strength bolts
When the high-strength bolt loosens, it will cause great mechanical energy, which will immediately act on the high-strength bolt and machine equipment, causing the destruction of the high-strength bolt. After the high-strength bolt is damaged, the machine and equipment cannot work normally, further causing damage to the machine and equipment. The external thread of the standard part subject to axial force is destroyed and the bolt is destroyed. Under the action of tangential force, the bolt is cut by laser and the bolt hole is elliptical in the standard part.
At this stage, the reasonable tightening method is Down's anti-loosening and collapsing method of external thread standard parts. Down's process has the characteristics of up and down processes. It can be used in conjunction with the upper and lower processes. The connection uses nuts with two different rotation directions. The nuts on the supporting surface are called tightening nuts, and the nuts on the non-supporting surface are called locking nuts. The tightening nut is pre-tightened before the locknut torque. In case of vibration and influence, the tightening nut will be loose. However, because the release direction of the tightening nut is the tightening direction of the tightening nut, tightening the lock nut can only avoid loosening of the tightening nut, thus causing the tightening nut to be invalid.
High-strength bolt connection has the advantages of simple structure, physical performance bar, release type, strong resistance, and not easy to loose under dynamic load. This is also a good way to connect. High-strength bolt is a unique wrench used to tighten nuts, which can cause a great and controllable preload. According to the nut and buffer plate, the same specification of pre-working pressure is created on the connecting member. Under the effect of prestress tension, the contact area of the connector will cause very large friction.
Obviously, as long as the axial force is lower than its own friction force, the parts are not easy to loosen and the connection cannot be destroyed. This is also the basic principle of high-strength bolt connection. High-strength bolt connection is based on the understanding of the friction between the surface layers of the connector to prevent them from rolling. In order to make the contact area have sufficient friction better, the locking force of prefabricated components and the friction force of the contact area should be strengthened.
The clamping force between components is completed by torque bolts, so the bolts must be made of high-strength steel plates, which is also called high-strength bolt connection. In high-strength bolt connection, the level of friction has a great practical effect on its bearing capacity. The test results show that the friction resistance is mainly affected by the appearance of the contact area and the raw materials of the module. In order to better improve the friction resistance of the contact area, sand blasting and steel brush cleaning are usually used to solve the contact area of the parts in the connection area.