Fastening unit for quick fastening of iron fittings, and iron fittings with such fastening unit

Unit for fastening iron fittings to furniture parts, comprising an expansion plug which axially receives a pin in a passage therein, the expansion plug being radially expansible by rotation of the pin from an insertion position to an expansion position of the expansion plug, the pin having a control head with a radial protrusion which defines a surface designed to imprison an iron fitting between it and an opposing top end of the expansion plug, characterized by the fact that the radial protrusion defines a flat surface substantially perpendicular to the axis of the pin which extends partially over a coupling seat formed in the opposing top end or the expansion plus around the passage for insertion of the pin in the expansion plug, a bottom of the deal forming a surface facing the flat surface of the radial protrusion, the seat having a side wall facing a corresponding side wall of the pin, and wherein the pin has a step extending radially which snap fits under a complimentary protrusion in the passage in the expansion plug.