The working principle of stainless steel hexagonal nut is self-locking by friction between nut and bolt. However, the reliability of this self-locking will decrease in dynamic load. On some important occasions, we will take some anti-loosening measures to ensure the reliability of nut locking. The use of locking nut is one of the anti-loosening measures.
The anti-loosening effect of stainless steel hexagon nut mainly depends on the interaction force between the nut and the bolt engagement thread. There are many ways to improve the interaction force between meshing threads, such as the structural improvement of nut threads, nylon roughening of nylon nuts, surface treatment of threads, etc.
There are also three types of lock nuts:
The first is to screw two identical nuts on the same bolt, and add a tightening torque between the two nuts to make the bolt connection reliable.
The second is a special locknut, which needs to be used together with a lockable gasket. The special locknut is not a hexagonal nut, but a middle round nut. There are 3, 4, 6 or 8 notches on the circumference of the nut (depending on the size of the nut and the product series of the manufacturer). These notches are not only the focus of the tightening tool, but also the clamping place of the lockwasher bayonet.
The third type is to drill through threaded holes (generally 2, distributed at 90 degrees on the outer circumferential surface) from the outer circumferential surface to the inner circumferential thread surface of the nut, which are used to screw in small-diameter countersunk screws, with the purpose of exerting a centripetal force on the threads and preventing the locking nut from loosening. The locking nut with good quality sold in the market is inlaid with a copper block with the same thread as the locking nut on the inner round surface of the nut, which is used to prevent the radial jacking screw from directly contacting with the locked thread and damaging the latter. This kind of locking nut is gradually applied to the shaft end locking occasions of rotating moving parts, such as the locking of the bearing at the mounting end of ball screw.
The second locking method is more reliable than the first one, but its structure is relatively complex. Compared with the first two types, the third type has the characteristics of better locking effect, simpler and more beautiful structure and smaller axial size.
Mainly characterized by convenient installation, integrity, no need for gaskets, convenient disassembly and reusability.
Generally used in automobile industry-cars, trucks, buses, compressors, construction machinery, wind power generation equipment, agricultural machinery, foundry industry, drilling equipment, shipbuilding industry, military and mining equipment, etc.
For details, please consult: stainless steel rivet nut.