DRILL BIT FOR DRILLING ON CASING STRING Russian patent published in 2020 - IPC E21B10/64 E21B10/46 

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to drilling equipment, in particular, to well drilling devices made from drilled materials, which can be used for drilling on a casing string. Drill bit for drilling on casing string includes housing, blades with PDC cutters for rock destruction. Blades with PDC cutters are made on spherical mandrel with holes, installed on inclined trunnion with channel, threaded to housing, having gaging blades with wear-resistant inserts, equipped with flushing channel connected with trunnion channel and holes of mandrel, in which water jet nozzles are installed. Mandrel, blades and trunnion are made of drilled material.

EFFECT: proposed design of drill bit allows drilling at casing with allowable torque without thread breakage and loss of tightness, and after its drilling it is possible to further deepen well of required diameter without laggings and landings of drill bit.

1 cl, 2 dwg