METHOD FOR USING ULTRASOUND TO LOCK A PLASTIC PLUG THAT PLUGS A STEERING BOX

The invention relates to a method that makes it possible to plug an orifice (1) of central axis (XX') pierced in a wall (2) of a box (3), using a plug (4) having a threaded hub (5) that is screwed into the orifice (1), said method comprising a rotation locking step (b) during which the rotation of the threaded hub (5) about the central axis (XX') is blocked by heating a portion of the plug (4) which is made of thermoplastic material so as to soften said thermoplastic material, then by forcing the softened thermoplastic material to penetrate into, and then solidify in, a female cavity (10) hollowed in the wall of the orifice so as to constitute a male member (11) which fits into said female cavity, the female cavity (10) being arranged in such a way that it forms, against the action of themale member (11), a guiding end stop which on the one hand prevents the male member (11), and therefore the hub (5), from rotating about the central axis (XX'), so as to oppose any rotary screwing/unscrewing of the plug (4) a