Mannesmann Aktiengesellschaft

Detlef Ramdohr

Johannes Gross-Weege

Karl-Heinz Brensing

Walter Knauf

The invention related to a process for producing pipes, especially large pipes, as per the UOE process, wherein the pipes, after internal and external seam welding, are incrementally calibrated by cold expansion up to half the pipe length. The cold expansion is also used for straightening. For this purpose, the pipe is clamped at the shortest possible distance in front of the expander head, the free pipe end is flexibley deformed, and the pipe is then cold expanded in a known manner. The prestress force thereby decreases and then, after the release of the clamping and the remaining prestress, the pipe moves incrementally by the amount of the expander step width, up to half the pipe length. The process is then repeated for the second pipe half.

Process and device for producing pipes as per the UOE process

The invention relates to a process for producing pipes, especially large pipes, according to the UOE process, wherein a pipe, after internal and external seam welding, is incrementally calibrated by cold expansion up to half the pipe length. The cold expansion is simultaneously used for straightening. For this purpose, the pipe is clamped at the shortest possible distance in front of an expander head, the free pipe end is flexibly deformed, and the pipe is then cold expanded in a known manner. The prestress force thereby decreases and then, after the release of the clamping and the remaining prestress, the pipe moves incrementally by the amount of and expander step width, up to one half of the pipe length. The process is then repeated for the second half of the pipe.

Diagonal rolls for stretching hollows are of a truncated-cone-like configuration, each with two shoulders and a recess in between, for cooperation with a cylindrical mandrel rod in order to obtain a two-stages-in-one reduction in wall thickness; the shoulders merge in smoothing surfaces.

Growing community of inventors

Krefeld, Germany

Detlef Ramdohr