Clad mud nozzle

In an earth boring drill bit of the type having a plurality of rotatable cutters on a body, the body having an internal passage with at least one outlet for the passage of drilling fluid, the passage having an enlarged diameter portion at its outlet that is separated from the passage immediately upstream by a downwardly facing shoulder, an improved nozzle comprising in combination:

• a nozzle shell having a cylindrical outer wall surface closely received within the enlarged portion, the shell having a circular upper rim in contact with the shoulder, a bore and a circular lower rim, the bore being tapered with a smaller diameter at its lower end that at its upper end;
• a nozzle insert having an outer wall surface bonded to the bore of the shell, and an extended portion that extends past the rim of the shell, the insert having a circular upper rim flush with the upper rim of the shell and a converging bore for receiving and discharging drilling fluid from the passage, the insert being formed of a material selected from the group consisting of tungsten carbide and ceramic;
• and
• a retaining ring extending around the extended portion of the insert, and received within a mating groove in the passage in contact with the shell's lower rim to retain the nozzle.

In an earth boring drill bit of the type having a plurality of rotatable cutters mounted on a body, the body having an internal passage with at least one outlet for the passage of drilling fluid, the passage having an enlarged diameter portion at its outlet that is separated from the passage immediately upstream by a downwardly facing shoulder, an improved nozzle comprising in combination:

• a nozzle shell having a cylindrical outer wall surface closely received within the enlarged portion, the shell having a circular upper rim in contact with the shoulder and having a circular lower rim, the shell having an axial bore that is tapered with a smaller diameter at its lower rim than at its upper rim;
• a nozzle insert of sintered tungsten carbide having an outer wall surface with a tapered portion bonded by adhesive to the bore of the shell, and having a cylindrical extended portion that protrudes past the lower rim of the shell and is of lesser diameter than the shell's lower rim, the insert having a circular upper rim in contact with the shoulder, and a converging axial bore, the diameter of the insert's bore at its upper rim being the same as the diameter of the passage immediately upstream of the shoulder;
• and
• a retaining ring extending around the extended portion of the insert, received within a mating groove in the passage, and in contact with the shell's lower rim to retain the nozzle.