Coupled piston ring method of manufacture

A method for fabricating a piston ring assembly including the steps

• forming first and second split compression ring members of uniform, generally rectangular cross-section, with parallel planar side surfaces, and with a cylindrical peripheral outer edge surface, dimensioned for side-by-side mating relation;
• finishing the mating side surfaces of said ring members to be fully contiguous in assembled mated relation, to effect a seal between said ring members;
• forming circumferentially overlapping, radially contiguous tongues in the ends of each ring member, with radially confronting sealing surface to provide radially sealed joints;
• forming an index tab integral with said first ring member by deforming a portion of the ring material, intermediate its ends and intermediate its edges, to produce a boss projecting generally perpendicularly from its mating side surface and having a sharp intersection with said side surface;
• said boss having a small transverse cross-section relative to the edge-to-edge width of said member;
• forming a recess in the mating side surface of said second ring member, intermediate its ends and intermediate its edges, dimensioned to receive and surround said boss with limited lateral clearance, to permit limited relative sliding movement of said first and second ring members in side-by-side relation;
• said recess having a small transverse crossj-section relative to the edge-to-edge width of said member;
• positioning said boss and said recess, on said respective first and second ring members, to maintain the joints of the mated ring members in rotationally spaced relation to each other.