How to prevent bolts from loosening

Screws are known as industrial meters, though small but not small.

Especially the plane rocket this high-tech content of the object, bolts can not be ignored, once loose, the consequences are unthinkable! How do bolts prevent loosening?

Bolted connections of aircraft generally have anti-loosening measures, such as fuses, open pins, bumpers, safety screws, etc., smaller plate nuts through the elliptical hole to achieve self-locking, the nut is not installed when the hole is elliptical, and through the nut tail groove clamping.
Fuse
A thin metal wire is used to connect two or more fasteners together. Two. When a component has loose tendency, it will be blocked by the fuse and stop developing.

Material: low carbon steel, stainless steel and brass, etc. commonly used is low carbon steel wire. In insurance, you can choose single or double fuse form, generally twisted into a braid in the form of double most widely used, as shown in the following figure.

Single-stranded fuses are commonly used in small groups of screws with very close spacing or in places that are difficult to reach, as shown in the figure.

Generally speaking, if threaded fasteners are clustered together, the form of mutual series insurance is much superior to separate insurance. The number of components that are insured in series should be determined on specific occasions.
Cotter pin
The installation of the cotter pin is as follows:

• Insurance film
• Insurance screw

In addition, thread self-locking is one of the most common anti-loosening measures, thread self-locking is generally achieved by a special thread tooth type, self-locking thread pitch (pitch) is small. Self-locking performance generally depends on the nut, unless the screw damage is particularly serious, so self-locking too small fault can generally be solved by replacing the nut.
What are the ways to prevent screw loosening in work?
General screw and nut connections are self-locking, under static load and working temperature changes little, will not be self-loose. However, under the impact, vibration or variable load, and when the working temperature changes little, the connection may be loose, affect the work, and even cause accidents. In order to ensure the safety and reliability of connection, effective anti loosening measures must be taken for connection between screw and nut.

1. Size to choose the right, slightly large or small screws, may be reluctant to use at the moment, but in the long run, will occur loose, or lock.
2. Processing special engineering plastics on the screw teeth can make the screw cap produce strong friction torque and reaction force during the locking process because the engineering plastics are pressed and extruded, produce contact of all teeth, provide absolute resistance to vibration, make the general screw become permanent strong anti-loosening screw, thoroughly solve the problem of loose connection between screw and screw. It's a problem.
3. Loosening method to increase friction. This kind of anti-loosening method is to make the screwed threads do not lose pressure because of the change of external load, so there is always friction resistance to prevent the connection from loosening. The loosening methods for increasing friction include installing spring washers and using double nuts.
4. Mechanical loosening. This kind of anti-loosening method is to use a variety of stop parts to prevent the relative rotation of the thread and parts to achieve anti-loosening. Mechanical loosening is more reliable, so there are more applications. Commonly used mechanical anti-loosening measures include open pin and groove nut, back washer and round nut, stop washer and nut, Shenlian steel wire and so on.
5. No loosening method can be dismantled. By means of positioning welding and spot riveting, the nut can be fixed on the bolt or the connector, and the screw can be fixed on the connector, thus achieving the effect of anti-loosening.

Source: China Fasteners Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)

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