Patent ID: 6250407
Filing Date: 2001-06-26
Classification: E21B,F16C

Abstract:
Rotary drilling bit comprising:a leg forming a journal, the journal defining a first axis;a rotary cutter rotatably mounted on the journal for rotation about the first axis, the cutter carrying rock cutting elements;first and second axially spaced radial bearing arrangements disposed in an interface between the journal and the rotary cutter, each radial bearing arrangement including an annular array of cylindrical rolling elements disposed between a radially outer race of the cutter and a radially inner race of the journal, each roller element being rotatable about a respective second axis disposed parallel to the first axis;an axial bearing arrangement arranged in the interface for absorbing axial forces between the rotary cutter and the journal;the leg including a filling opening arranged substantially parallel to the first axis for enabling the rolling elements of the first radial bearing arrangement to be installed, with the rotary cutter in a mounted state on the journal;the rotary cutter including a radial flange arranged to radially overlap the rolling elements of the first radial bearing arrangement for securing the rotary cutter axially on the journal, the flange disposed axially in front of the filling opening and axially behind the first radial bearing arrangement and including a recess aligned with the filling opening for accommodating the passage of cylindrical rolling elements being installed; anda locking pin disposed in the filling opening for preventing removal of the cylindrical rolling elements of the first radial bearing arrangement, the locking pin including a lip projecting forwardly past an axial rear end of the flange, the lip disposed radially inwardly of the flange to avoid blocking rotation of the rotary cutter, the lip terminating axially behind the cylindrical rolling elements of the first radial bearing arrangement.