System for constricting a tube wall

An apparatus for constricting an end of a metallic tube (or worktube) to form an arcuate-walled portion that has an outer surface is provided. The apparatus comprises a means for rotating the tube on its axis, a movable means for heating an end portion of the tube, and a forming rolling means. The forming rolling means includes a forming roller adapted for applying pressure on the end portion of the tube along successive lines of contact to constrict progressively the end of the tube. The movement of the forming rolling means is orchestrated with the movement of the means of heating. In a preferred embodiment, each line of contact has a substantially straight portion.