Series of Self-Locking Nuts

Ⅰ. Working Principle of Self-Locking Nuts

An arc-shaped surface is arranged at the root of the nut thread. When the externally-threaded fastener is pre-tightened, the crest of the external thread slightly yields and presses against the arc-shaped surface, which effectively protects the thread crest. During tightening, the thread crest firmly bears against the curved surface. Force is transmitted to the main body of the fastener beneath the thread and generates powerful locking force.

From the mechanical perspective, thread anti-loosening mechanism consists of two core factors. First is the geometric locking effect. The wedging action of external-thread crests on the curved surface creates radial elastic deformation and produces self-reinforcing locking torque. Second is the friction-damping effect. The curved contact surface enlarges the actual contact area of the thread pair and raises the friction coefficient to dissipate external vibration energy. Combined action of the two effects enables the nut to deliver far longer anti-loosening service life than ordinary nylon-insert lock-nuts and all-metal lock-nuts in transverse vibration tests.

Ⅱ. Applications of Self-Locking Nuts

Moreover, the curved-surface thread design boasts excellent processing adaptability. The structure features high tolerance for machining errors and maintains dependable locking performance even with minor manufacturing deviations. It serves as an essential threaded-connection solution for key joints in reliability-critical industries including aerospace, rail transit and construction machinery.