Obturator for an opening produced in a metal sheet

An obturator for an opening produced in a sheet member having two opposite major faces communicated with each other by the opening, said obturator comprising:

• a collar having an elastically deformable lip adapted to come into abutment with one of the major faces of the sheet member:
• at least one tooth pivotally joined to said collar;
• a central portion movable with respect to said lip, along an axial direction of said obturator, and between upper and lower axial positions to cause said at least one tooth to pivotally move between unlocked and locked positions of said obturator, respectively, said at least one tooth adapted to come into abutment with the opposite face of the sheet member in the locked position of said obturator;
• wherein
• when said central portion is in the upper axial position, a lower end face of said central portion is axially spaced from and is not in direct contact with an upper end face of said tooth, the upper end face of said tooth being located in an intermediate position on an axial path along which said central portion moves between the upper axial position and the lower axial position;
• and
• when said central portion is in the intermediate position, the lower end face of said central portion is in direct contact with the upper end face of said tooth, whereby a further movement of said central portion from the intermediate position towards the lower axial position will cause said tooth to pivotally move to the locked position of said obturator.