Method for manufacturing fully sealed piston ring

A method for fabricating a unitary, fully sealed piston ring including the steps of:

• (a) forming first and second split ring members with each having parallel planar side faces and generally concentric outer and inner edge faces, with said outer edge face being cylindrical when a split ring member is compressed to its intended final diameter, and each of said split ring members being formed from an annular blank whose initial circumference is greater than the intended final circumference of the piston ring by a length identifiable as the insert length, and each of said ring members being split in a generally radial direction to form first and second ends;
• (b) forming circumferentially overlapping, radially contiguous fingers at the ends of said split ring members, including a radially outer finger whose exterior face constitutes a circumferential extension of the outer edge face of a split ring member, and including a radially inner finger whose interior face constitutes a circumferential extension of the radially inner face of a split ring member, with said fingers having a length less than the insert length of said blank;
• (c) finishing said finger faces and said outer and inner edge faces of the ring members for sealing relation with their respective co-acting surfaces;
• (d) positioning said first and second split ring members in overlying, side-by-side and contiguous relation, with the respective first ends of each of said split ring members circumferentially overlapping a body portion of the other ring member, whereby a joint is made up between the first and second ends of each split ring member when the ring member is compressed to its final diameter, and said made-up joint for each ring member overlies a body portion of the adjacent ring member, and the first and second ring members being oriented in a generally horizontal position so as to form an angle of no more than fifteen degrees with respect to horizontal at the time that joining is accomplished;
• and
• (e) permanently joining said two ring members into a unitary assembly by means of only a single and localized silver solder joint between confronting side faces of the two ring members, each confronting side face having a flat surface with the entire surface extending only in a single plane and said solder being disposed between the flat surfaces, with the two ring members being positioned so that the silver solder joint is in close proximity to each of the two radially outer fingers, and the joining step being accomplished after the recited finishing step, and the amount of joining material being sufficiently small as to obviate any further finishing after the joining step, whereby the ring is ready for use immediately after the joining step.