DRAG DRILL BIT Russian patent published in 1997 - IPC

FIELD: drilling tools; in particular, drag drill bits for coring. SUBSTANCE: drill bit has body, longitudinal water courses, blades reinforced by cutting members rigidly secured to body. Installed inside body is bushing having radial recesses on lower end to receive blades. Internal side surfaces of blades are stepped in shape and installed for engagement with upper end and external surface of bushing. Bushing may have stiffening ribs, water courses are formed by side surfaces of body and bushing and front end rear faces of blades and stiffening ribs of bushing. EFFECT: higher efficiency. 3 cl, 2 dwg