Patent ID: 7908731

Claim:
A method of producing a double fold at a first pipe end, comprising the steps of: providing first and second motor-driven laterally-displaceable shaping rollers and a lower laterally-displaceable delivery roller associated with each shaping roller, the shaping rollers being in fixed axial positions; rotating the first shaping roller and putting the first pipe end thereon to establish peripheral contact between the inside of the pipe and the first delivery roller; rotating the second shaping roller and moving the second shaping roller in a tangential plane until it engages with the exterior of the pipe so that the pipe end jointly rotates in synchronism with the second shaping roller; pushing the second shaping roller stepwise in the tangential plane towards the first shaping roller a distance of the width of the double fold against the first shaping roller so that a continuous folding tab oriented outwardly to the pipe is formed at the pipe end between the second shaping roller and an upper surface of the first delivery roller; pushing the second delivery roller in a direction towards the first shaping roller in a second plane situated at a lower level than the tangential plane by at least twice the thickness of the pipe material, whereby the first delivery roller is laterally drawn back under the influence of the second shaping roller in synchronism in the opposite direction whereby a distal portion of the folding tab is folded back towards the pipe such that the folding tab is formed into a double fold flange.