Why do the bolts of aircraft rockets not loosen under the super high impact force?

Why do the bolts of aircraft rockets not loosen under the super high impact force?

Aircraft bolt connections generally have anti-loosening measures, such as fuses, split pins, fuse plates, and safety screws. The smaller pallet nuts are self-locking through elliptical holes. This kind of nut has an elliptical hole when it is not installed. It is clamped by the slotted end of the nut.

Fuse: A thin metal wire is used to connect two or more fasteners together. When a component has a tendency to loosen, it will be restricted by the fuse and stop developing.

Material: Low-carbon steel, stainless steel, brass, etc. Generally, low-carbon steel wire is commonly used. For insurance, single-strand or double-strand fuse can be used. Generally, the form of double-strand twisted braid is the most widely used, as shown in the figure below.

Single-strand fuses are generally used in small groups of screws that are closely spaced or in places that are not easily accessible, as shown in the figure.

Generally speaking, if the threaded fasteners are clustered together, the form of mutual tandem insurance is much better than independent insurance. The number of components in a series fuse should depend on the specific occasion.

Split pin:

The installation form of split pin is as follows:

safety pin:

Safety screw:

In addition, thread self-locking is one of the most common anti-loosening measures. Thread self-locking is generally achieved through a special thread profile, and the thread pitch (pitch) of self-locking threads is small. The self-locking performance generally depends on the nut. Unless the screw is particularly damaged, the self-locking force is too small and the fault can generally be solved by replacing the nut.

What are the ways to prevent screws from loosening during work?

Generally, the screw and nut connection are self-locking, and will not loosen by themselves when subjected to static load and working temperature changes little. However, under the action of shock, vibration or variable load, and when the working temperature does not change much, this connection may loosen, affect the work, or even cause an accident. In order to ensure the safety and reliability of the connection, effective anti-loosening measures must be taken for the connection of screws and nuts.

1. Choose the right size. A slightly larger or smaller screw may be barely used at the moment, but in the long run, it will inevitably become loose or locked.

2. Special engineering plastic is processed on the screw thread , so that during the locking process of the screw and nut, the engineering plastic is squeezed to produce strong frictional torque and reaction force, resulting in full-pitch contact, providing absolute vibration Resistance makes ordinary screws become permanent and powerful anti-loosening screws, which completely solves the problem of loose connection between screws and screws.

3. Anti-loose method to increase friction. This kind of anti-loosening method is to prevent the tightened threads from losing pressure due to external load changes, so there is always frictional resistance to prevent the connection from loosening. The anti-loosening methods to increase friction include installing spring washers and using double nuts.

4. Mechanical anti-loosening. This kind of anti-loosening method uses various stop parts to prevent the relative rotation of the thread and the parts to realize the anti-loosening. The mechanical anti-loose is more reliable, so it has more applications. Commonly used mechanical anti-loosening measures include split pins and grooved nuts, non-return washers and round nuts, stop washers and nuts, and Shenlian steel wire.

5. Anti-loose method that cannot be dismantled. Using tack welding, spot riveting and other methods to fix the nut on the bolt or the connected part, the screw can be fixed on the connected part to achieve the anti-loosening effect.