Abstract: A transition forming unit is provided for forming a strip of U-shaped cross-sectional configuration into a generally annular shaped cross-sectional configuration. The forming process is performed by a plurality of roll assemblies adjustably mounted on a pair of spaced longitudinally extending beams, one disposed on each side of the longitudinal axis of the forming unit. The beams are adjustable in respect of the longitudinal axis of the forming unit. A hold down assembly is provided for controlling the alignment of the U-shaped strip as it passes through the forming unit. The roll assemblies are mounted on each beam to absorb thrust loads produced during the forming process.