Aktieselskabet Nordiske Kabel-Og Traadfabriker

Hans Rosendal

Poul Erik Braad

Knud B Jensen

Flemming Sevaldsen

A process and apparatus for continuously transforming a flat metal strip into an elongated pipe, in which the strip is fed through a forming tool along a curved forming path wherein the longitudinal edge portions are progressively turned up into cross-sectionally arcuate portions leaving between a substantially cross-sectionally rectilinear section, the width of which progressively decreases during travel of the strip through the forming tool. The curved forming path in the tool is such that it has a radius of curvature R(z) in its longitudinal direction, the arcuate portions each having a radius r.sub.o and the decreasing width of said rectilinear section being 2x(z) (wherein z is the distance of travel through the tool). The radius of curvature R(z) is controlled in sole dependence on r.sub.o and the differential quotient x'(z). In the resulting elongated tube, relative differences in travel distance between arbitrary areas in a transverse cross-section of the strip forming the pipe are substantially completely eliminated without plastic deformation in the longitudinal direction.

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Glostrup, Denmark

Hans Rosendal