Obturator with improved retention in a metal sheet aperture

An obturator for an aperture (8) produced in a metal sheet (9), comprising a central dome (1), a peripheral lip (2) and an annular part (3) extending between said dome (1) and said lip (2), said annular part (3) having a shoulder (4), said dome (1) being adapted to deform between a raised starting position and a lowered position of locking of said obturator, wherein said dome (1) is inverted in relation to the starting position, said annular part (3) being adapted to expand between said starting position and said locking position and to be maintained expanded by said dome (1) inverted in said locking position, the lip (2) being adapted to come into abutment against a face (9a) in said metal sheet surrounding the aperture (8) and the shoulder (4) being adapted to pass through the aperture during inversion of the central dome so as to be in flush abutment against an opposite face (9b) in said metal sheet surrounding said aperture (8) in said locking position;

• said lip and shoulder thereby coacting by engaging said faces to support the central dome and annular part in said aperture in said locking position;
• wherein said shoulder (4) is formed by a series of teeth (4) delimited by slots (5) wherein the central portion (1a) of said dome (1) has a thicker part made of plastics material and a face (10) domed towards the outside of the dome (1) in the starting position and towards the inside of the dome (1) inverted in the locking position.