Is based on mechanical rock fragmentation using three rotating cones mounted on bearings. Each cone has cutting teeth (either milled steel teeth or tungsten carbide inserts) that crush and gouge the rock as the bit rotates.
Tricone Bit Mechanism
Structure:
-Three conical rollers (cones) are mounted on the bit body.
-Each cone is set at a specific angle and offset to maximize rock contact.
-Teeth are arranged in rows for progressive cutting.
Rotation:
-The entire bit rotates via the drill string (powered by the rotary table or top drive).
-As the bit rotates, each cone counter-rotates on its own axis due to contact with the formation.
Bearings:
-Cones rotate on journal bearings (roller or ball-type), often sealed and lubricated.
-Modern bits have sealed bearings with pressure compensation systems to extend bit life.
Mud Circulation:
-Drilling mud flows through nozzles between the cones.
-Functions:
-Cool and clean the bit
-Carry cuttings to the surface
-Prevent bit balling
Summary of Bit Mechanism:
- Bit rotates, cones roll on formation.
- Teeth engage rock, crush, gouge, or shear it.
- Cuttings are lifted by mud flow.
- Bearings allow cone rotation and absorb loads.