What are the common anti-loosening measures for threaded connections? [Mechanical knowledge] Seeking solutions

Commonly used anti-loosening measures are:

(1) Friction locking

This is the most widely used anti-loosening method, trying to increase the pressure and friction between screw pairs and prevent relative rotation. For example, elastic washers, double nuts, self-locking nuts and nylon insert locking nuts are used.

(2) mechanical locking

Restrain the screw pair with easily replaceable metal elements. For example, bolts and nuts are restrained by cotter pins, and the heads of a set of screws are restrained by wires.

(3) Riveting locking

Turn the screw pair into a fixed pair, thus eliminating the possibility of relative rotation, such as welding, punching, gluing between screw pairs, etc. Mostly used for connections with little or no disassembly.

Extended data

Causes of loose threaded connection

1, design defect

(1) The strength of bolt selection is insufficient.

Bolt connection generally adopts the yield point tightening method, that is, the pre-tightening force of bolt should reach the yield strength of bolt material, and considering the safety factor, it should generally not exceed 80% of the yield limit of bolt material. The yield strength of bolts of different materials is different, which also means that the maximum preload that bolts of different materials can bear is different.

(2) The connection lacks locking.

Under the conditions of load change, vibration, impact, etc. The compression force and pre-tightening force of bolted parts will gradually decrease or even disappear, which will lead to the loosening of threaded connection after repeated times, and finally lead to the loosening of bolts, especially the form of bolt-nut cooperation.

2. Insufficient pre-tightening force during assembly.

The pre-tightening force that the bolt can achieve in the tightening process directly determines the clamping force between the two connecting parts. Insufficient pre-tightening force will inevitably lead to the loosening of connecting bolts and eventually the loosening of connecting parts.

3. Improper assembly method

During the assembly process, a single bolt and a plurality of bolts are tightened. In view of the tightening state of multiple bolts, especially the regular distribution, the method and mode of bolt tightening are extremely important, which directly affects the actual preload of each bolt.

4, connector installation hole processing quality

When two connectors are connected, the size of the threaded hole or the mounting bolt hole is particularly important, and the thread specification of the threaded hole directly affects the pre-tightening force obtained by the bolt.

Baidu Encyclopedia-Anti-loosening Thread

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