Patent ID: 7311159
Filing Date: 2007-12-25
Classification: E21B,F16C,F16J

Abstract:
1. An earth-boring bit with an improved mechanical face seal assembly, the earth-boring bit comprising: a bit body; at least one cantilevered bearing shaft extending inwardly and downwardly from the bit body; at least one cone mounted for rotation on the bearing shaft; and a seal assembly disposed between the bearing shaft and the cone, the seal assembly including at least one rigid seal ring concentric with the bearing shaft; the seal ring having a body of cemented carbide; an annular PCD layer located on the body; a binder material selected from a group consisting of cobalt, nickel and alloys thereof interspersed within the cemented carbide and within the PCD layer; and the PCD layer having an exterior surface with an annular binder-free region of a selected depth within the PCD layer that is substantially free of the binder material, the depth of the binder-free region being less than the thickness of the PCD layer.