Patent ID: 6220374
Filing Date: 2001-04-24
Classification: E21B

Abstract:
A rotary cone drill bit for forming a bore hole, the drill bit comprising:a bit body having an upper portion adapted for connection to a drill string for rotation about a longitudinal axis of the bit body;a number of angularly spaced support arms extending from the bit body with each support arm having an inside surface with a journal connected thereto;each journal projecting generally downwardly and inwardly with respect to the axis of rotation for the bid body;each journal having a generally cylindrical configuration with a first end connected to the inside surface of the respective support arm and a second end extending from the indside surface of the respective suport arm;a plurality of cutter cone assemblies equal to the number of support arms with each cutter cone assembly rotatably mounted on one of the journals;each cutter cone assembly having an opening with a cavity extending therefrom and sized to receive the respective journal therein such that a gap is formed between the exterior of each journal and the interior surface of the respective cutter cone assembly defined by the cavity;a first annular groove formed in the exterior of each journal intermediate the first end and the second end;a second annular groove formed in the interior of each cutter cone assembly adjacent to the first annular groove of the journal;a plurality of ball bearings disposed within the first annular groove and the second annular groove to rotatably secure each cutter cone assembly to its respective journal;a thrust flange formed on the exterior of each journal intermediate the first annular groove and the second end of the journal;a journal bearing surface formed on the exterior of each journal intermediate the first annular groove and the first end of the respective journal;the thrust flange of each journal having a first diameter and the journal bearing surface of each journal having a second diameter;a thrust washer disposed around the journal and between a thrust surface of the thrust flange and the interior surface of the cutter cone assembly;wherein the thrust washer has an outside diameter larger than the first diameter of the thrust flange.