TUBE MADE OF METAL STRIP BY MEANS OF SPIRAL SEAMING AND A DEVICE INTENDED FOR A SPIRAL SEAMING TUBE MACHINE FOR THE PRODUCTION OF SUCH A TUBE

摘要

A machine for forming a spirally seamed tube from a continuous metal strip formed with at least one integral stiffening ridge between the spiral seams formed at the longitudinal edges of said metal strips. The machine comprises prebending rollers for forming a longitudinal ridge in said metal strip and a guiding unit for bending the strip to form a spiral tube having an axis extending transversely with respect to the longitudinal direction of the metal strip. The machine further comprises seaming rollers for joining together adjacent edges of the spiral tube. A pair of ridge flattening rollers are provided between said prebending rollers and said guiding unit for flattening of the foot of the ridge to form in cross-section a loop forming a space between the walls of said ridge inside said loop.