The working principle of the nut is self-locking using the friction between the nut and the bolt. However, the reliability of this self-locking is reduced in dynamic loads. In some important occasions, we will take some measures to prevent loosening and ensure the reliability of the nuts. Among them, using lock nuts is one of the measures to prevent loosening.
Nuts
There are also three types of lock nuts:
The first is to use two identical nuts to be screwed onto the same bolt, and a tightening torque is added between the two nuts so that the bolt connection is reliable.
The second type is a special locking nut that needs to be used with a type of locking washer. The special lock nut is not a hex nut but a 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 manufacturer's product series), this Several gaps are both the focus of the tightening tool and the snap-in of the bayonet washer.
The third method is to drill threaded holes (generally two, 90 distributed on the outer surface) from the outer surface of the nut to the inner surface of the threaded surface. It is used to screw in a small-diameter countersunk head screw in order to give the thread. Apply a centripetal force to prevent the lock nut from loosening. A relatively good quality lock nut sold on the market is provided with a small piece of copper which is in line with the thread of the lock nut on the inner round surface of the nut, for avoiding that the radial top screw directly contacts with the locked thread and damages the latter. . This kind of lock nut gradually starts to be applied at the shaft end locking position of rotary motion parts.
Such as the ball screw mounting end of the bearing to prevent loosening. The second anti-loosening method is more reliable than the first one, but the structure is relatively complicated. Compared with the first two types, the third bell has the characteristics of better anti-loosening effect, simpler structure, and smaller axial dimension.