Rolled or extruded aluminium al-mn alloy products with improved corrosion resistance

摘要

The tamperproof closing device for a receptacle having a threaded collar comprises a screw cap (1) consisting of a bottom (8) and a cylindrical skirt (9) having inner threading for co-operation with the corresponding threading (5) on the collar (2) and extended by a tamperproof ring (13) which is attached by frangible means (20). The collar has a plurality of outer radial notches arranged at the base thereof. Said notches are circumferentially oriented and the ring comprises a plurality of inner radial reliefs (15) whose profile is complementary to that of the notches (7). The orientations and dimensions of the notches (7) and reliefs (15) are determined in such a way that the second items can pass onto the first items in the direction of screwing as a result of elastic deformation of the constitutive material and can prevent the same from occurring in the opposite direction. The reliefs (15) are formed on an annular lip (14) which is turned back and originates from the tamperproof ring (13). When it leaves the mould, said lip (14) forms an annular truncated appendix converging slightly towards the inside and bearing the reliefs on the outside (15).