DRILLING BIT AND CUTTING INSERT FOR IT Russian patent published in 2000 - IPC

FIELD: drilling equipment. SUBSTANCE: cemented carbide cutting insert is mainly designed for percussive drilling and has cylindrical mounting part and external part including relatively flat surface spreading from mounting part to front end of insert. Mounting part has central axis and definite radius. Insert body from cemented carbide includes a number of zones one of which is surface zone fully surrounding the core of cutting insert. Boundary of two adjacent zones describes the trajectory which is not symmetrical at least in one cross-section in side view relative to central axis, and trajectory in cross-section in top view is not symmetrical to at least one axis perpendicular to central axis. Percussive drilling bit includes shaft, drilling head located on front end of the shaft and having the first longitudinal axis. Drilling head has face end directed forward with face surface, shell surface spreading mainly in longitudinal direction and confining external periphery of the drilling head and a number of holes formed in the face end. Each hole is mainly cylindrical in shape and serves to receive the cutting insert from cemented carbide. EFFECT: increased durability of drilling bit due to increased wear resistance of cutting insert. 11 cl, 18 dwg