Spontaneous unwinding of threadedconnections entails the danger of premature failure of the most diverse machines and mechanisms. Grover's washer effectively enough prevents this undesirable phenomenon, but it has its drawbacks. Firstly, this is an extra assembly unit, and secondly, it can simply be forgotten by another disassembly.
The old way is to screw the lock nut,that is, one more nut wrapped over the main one. This method is effective, but not always applicable, especially in cases where the weight of a machine or mechanism is important, for example, in aviation or space-rocket technology.
In order to improve performanceproducts of almost all branches of mechanical engineering, invented nuts self-locking, that is, those with which vibration and other mechanical vibrations are at fault.
There are several ways to achieve this result.
The first method of improving the stability of threadedconnection consists in making the mounting parts in such a way that the nuts self-locking during screwing are subjected to elastic deformations on the windings, which is provided by the so-called "interference", i.e., a positive tolerance providing increased friction during tightening.
Подобных деформаций можно добиться также при multi-step cutting of the nut and bolt. With each next turn, this difference will increase the force required to disassemble the assembly, which eliminates arbitrary self-development.
There is also a self-locking nylon nutring by means of which the mechanical braking of any of their course after screwing is carried out. The elastic polymer insert also acts as an additional damper, i.e., a damper for mechanical vibrations, which also positively affects the reliability of the threaded joint.
The tool for solving the problem is also the thickening inlower part with a special incision creating an increased friction after it is pressed against the surface of the fixed part. Such self-locking nuts are easy to recognize, they differ significantly in appearance from their usual hexahedral counterparts.
There are other ways to preventundesirable and untimely unscrewing. For joints that do not experience significant mechanical loads during operation, steel-stamped self-locking nuts can be used, which create increased resistance in the reverse motion due to the springing properties of the material of manufacture.
It is also possible to use additional gear rims fixed to the bottom of the fastener. Strengthening friction at the points of contact, the protrusions securely fix its position.
Despite the variety of forms, any fasteningthe part is made according to state and international standards, including a self-locking nut. GOST 5915-70 and DIN 985 are the documents regulating their size (they come with metric and inch threads) and the material (ordinary, alloyed or stainless steel).
