Method of mounting a metal sheet ring assembled and welded in a carrier hoop to conform the annular cooling tube of a piston of internal combustion engine

A method of mounting a metal sheet ring on a carrier hoop to form an annular cooling tube of a piston of an internal combustion engine the metal sheet ring, having a cross section including a web extending between two fins projecting towards the carrier hoop, wherein the free ends of said fins rest on and couple to respective annular seats each defined in a radially internal face of the carrier hoop, said free ends being sealed by respective annular welding beads extending along the free ends the carrier hoop, thereby forming the internal annular cooling tube, which has an inside surface defined by the metal sheet ring and an internal diametrical surface of the carrier hoop extending between the annular seats, comprising:

• providing the metal sheet ring as a preform, outside the carrier hoop, having a cross section including a web defining an internal diameter and extending between two preform fins that both project from the web such that free ends of both of the fins lie outward of the web with respect to the radial direction of the preform, wherein the diameter of the free end of a first of said preform fins is less than the diameter of the interior surface of the carrier hoop in which its annular seat is defined, whereas the diameter of the free end of the other preform fin is greater than the diameter of the interior surface of the carrier hoop in which its annular seat is defined;
• positioning said preform in the carrier hoop (6);
• and
• subsequent to the positioning, configuring said preform into said annular cooling tube defined by free ends of the metal sheet ring in engagement with the annular seats of the carrier hoop.