Abstract: An improved apparatus for continuously forming spirally corrugated metal pipe from an elongated sheet of metal which is first impressed with longitudinal corrugations in a corrugating device and the spiralled into a pipe in a three roll forming device, each roll of which is composed of a plurality of individual rollers. Each individual roller is mounted for rotation about its axis in an individual roller yoke, with each of the roller yokes of each roll being in constant abutment, but with adjacent roller yokes being uninterconnected. Individual roller yokes of each roll are positioned along a guide, with each yoke being both freely displaceable along the guide along a horizontal path generally parallel to the axis of the formed pipe, and also pivotable about a vertical center axis.

Abstract: The invention concerns an apparatus for forming annular circumferential corrugations in the end of a helically corrugated seamed pipe. Two corrugating rolls, a backup roll and a thrust roll, engage the wall of the pipe to form the annular corrugations. The backup roll normally engages the inner wall of the pipe, and the thrust roll, the outer wall. The thrust roll is formed from a plurality of independent and transversely movable roll sections urged with a predetermined force into engagement with the pipe by a support composed of a group of rolls engaging the periphery of a corresponding roll section and mounted within a pivotable lever frame. The predetermined force is provided by a pressure-controlled hydraulic cylinder acting through each of the lever frames.