The invention concerns a functional element, in particular a bolt, consisting of a shank portion (14) and a head portion (16) designed to be assembled riveted with a plate element, in particular a sheet metal part. The invention is characterised in that the head portion (16) is hollow and has practically the same external diameter as the shank portion. When mounted, the hollow head portion (16) of the functional element (10) forms a riveting edge (37) on one side of the sheet metal part and an annular groove (52) on the other side of the sheet metal part, the annular groove (52) acting as a flange. The invention further concerns a method for fixing the functional element in a sheet metal part and the resulting assembling element (16), as well as a matrix and a swaging assembly.