Patent ID: 8286460

Claim:
A method for forming an edge or collar at the open end of a metal holder defined by an extruded metal rough piece, deep-drawn or deep-drawn/wire-drawn, adapted to form bottles for beverage and food sectors or for technical use wherein the method can be carried out on a tapering machine, said metal holder adapted to be closed by a cap, said method includes in sequence: a first operating deformation stage of a basically cylindrical upper end portion ( 12 ) of said metal holder ( 10 ), turning it outwardly so as to obtain an initial stage collar ( 18 ) with a basically circular cross-section; a second intermediate deformation stage performed on said initial stage collar ( 18 ) squeezing it in the radial direction and stretching it towards a bottom of said metal holder ( 10 ) to form a second stage collar ( 18 â€²); and a third deformation stage performed on said second stage collar ( 18 â€²) to form a final stage collar ( 18 â€³) with a complex ovoidal profile, whereby said profile is adapted to allow at least two caps of different type to be applied to said metal holder ( 10 ); wherein said first operating deformation stage and said second intermediate deformation stage are accomplished by an edging mandrel ( 22 ) and said third deformation stage is accomplished by a rolling mandrel ( 24 ) both provided with axial movement and always rotating and intervening sequentially on the metal holder, said edging mandrel comprising pivots ( 54 ) and a centering device ( 38 ) inserted in the metal holder for supporting the metal holder and the rolling mandrel ( 24 ) comprising shaped rolls ( 118 ) and a centering device ( 102 ) inserted in the metal holder for supporting the metal holder, with the surface of the pivots ( 54 ) and shaped rolls ( 118 ) shaped as a function of the type of the edge or collar to be formed.