Patent ID: 7464453

Claim:
A process for producing a connecting flange ( 32 ) for a butt joint on an end of a pipe section ( 10 ) of sheet metal with circular or oval cross section, the process comprising: (a) sliding a pipe piece over the outer side of a pipe section ( 10 ), so that the pipe piece forms on the outer side of the pipe section ( 10 ) a reinforcing ring ( 47 ) lying flush against the pipe section ( 10 ), (b) bending said end of pipe section ( 10 ) and an end of the reinforcing ring lying thereupon, from a pipe wall ( 12 ) of pipe section ( 10 ) outwards, to form a projecting ring rim ( 14 ) in the pipe section ( 10 ) and to form a flank ( 44 ) in the reinforcing ring ( 47 ), the flank ( 44 ) of the reinforcing ring ( 47 ) lying against at least a radially inner part of the projecting ring rim ( 14 ), thereby forming the connecting flange wherein in step (a) said pipe piece is slid axially over the outer side of the pipe section ( 10 ) until an axial segment of the end of the pipe section ( 10 ) is exposed, and wherein said exposed end of pipe section ( 10 ) is bent from the pipe wall ( 12 ) outwards prior to step (b) to form, following step (b), a clamp flank ( 24 ).