DRILLING BIT AT CASING STRING Russian patent published in 2020 - IPC E21B10/64 

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to drilling equipment, in particular, to well drilling devices made from drilled materials and can be used for drilling on casing string. Drill bit for drilling on casing string includes body with holes, blades with PDC cutters for destruction of rock. Housing with holes is made integral with cutting blades with PDC cutters from drilled material. Bit includes adapter with calibrating blades, having internal thread for connection with casing string and made of non-drilling material. Housing with holes with integral cutting blades with PDC cutters is connected with adapter by inner conical thrust thread. Between cutting blades with PDC cutters there are shortened cutting blades limited by drilling zone. Drilling width of cutting blades reduces in drilling zone. Proposed bit for drilling on casing string is reliable and simple design due to manufacturing of housing with holes from drilled material together with cutting blades with PDC cutters.

EFFECT: reduced time of drilling of drill bit by manufacturing of calibrating blades on adapter made of non-drilled material, production of shortened cutting blades limited by drilling zone and made of non-drilled material, and due to reduced width of cutting blades in drilling zone.

1 cl, 2 dwg