CROWN BIT Russian patent published in 1996 - IPC

FIELD: rock cutting tools. SUBSTANCE: crown bit body has radial recesses on its end face and hard metal inserts with radial shape of core-forming part having stop in crown bit center and secured in recesses by soldering; additional recesses interconnecting the recesses receiving hard metal inserts. Width of additional recesses is smaller than the thickness of hard metal inserts. Additional recesses separate the side surfaces of recesses for hard metal inserts and soldering seams into two symmetrical parts connected by insert bases and recess bottom. Due to this, soldered surfaces acquire simple symmetrical configuration and side seams become interrupted and of short length. This is why value of internal stresses in hard metal inserts is reduced to increase service strength of drill bit. EFFECT: higher service strength of crown bit due to reduced internal stresses in hard metal inserts. 3 dwg