Fastening device

A fastening device of the type adapted to be inserted into a bore formed through a hollow partition or wall, which comprises a tightening screw provided with a head adapted to engage the outer surface of the partition, a nut screwed on the screw end opposite said head, a tubular plug of deformable material surrounding said screw and disposed between the screw head and said nut, on the outer surface of said plug, a plurality of longitudinal splines separated by gaps, in the bottom of each gap, a slit extending along at least one portion of the plug length, except at the ends thereof, on the nut face registering with said plug, a series of spaced deformable lugs equal in number to the gaps formed between the longitudinal splines of the plug, and each lug is engaged in a gap between two adjacent longitudinal splines of the plug, so that said nut cannot rotate relative to said plug when said tightening screw is screwed into the former and thereby said plines of said plug are not only being deformed in a longitudinal direction during the screwing but also twisted and intermingling with one another so as to form an anchoring knot, said lugs of said nut being so deformable that when said splines of said plug are twisted, said lugs of said nut are also twisted and still retained in said gaps between said splines so as to form an integral part of said anchoring knot.