PROTECTED BACK-UP RINGS FOR METAL FACE SEALS AND EARTH BORING TOOLS INCORPORATING THE SAME

An earth-boring rotary drill tool may comprise a body comprising a pin, a roller cone mounted on the pin, and a seal assembly disposed between the pin and the roller cone. The first ring may comprise longitudinally converging sidewall surfaces defining a minimum radial thickness of the first ring at points of tangential intersection with a convex curved surface spanning a radial thickness of the first ring. The second ring may comprise a concave surface located and configured to interface over an area of contact with the convex curved surface of the first ring. The third ring may be positioned adjacent to, and concentric with, the second ring. The second ring may be disposed radially inward from the third ring. The first ring may also contact a surface of the roller cone or an insert ring adjacent the roller cone to form a seal between the first ring and the surface.