FLUID JET ASSISTED CONE-TYPE DRILL BIT ASSEMBLY AND METHOD

摘要

A tricone type of drill bit assembly (10) including an arrangement of lugs (18) which rotatably support cone-type cutter heads (30, 32, 34), specifically three such cutter heads, circumferentially about a common central axis (26) of the assembly (10) such that a segment of each cutter head defines a corresponding segment of the drill face (44) of the assembly between its central axis (26) and the outermost periphery of its drill face. The particular drill bit assembly (10) disclosed herein is an improvement over known such assemblies in that it provides at least one high pressure fluid cutting jet (42) located between two of the cutter heads at a point radially spaced inward from the outer periphery of the assemblies drill face. In particular embodiments shown, a number of such cutting jets are provided along a radial line between the outer periphery of the drill face and the common axis (26) of the assembly.