CROWN BIT Russian patent published in 2002 - IPC

FIELD: air percussion tools, crown bits of large diameter with rock- breaking inserts. SUBSTANCE: crown bit has separable ring and body with tail and butt parts. Separable ring and butt part of body are reinforced by hard-alloy inserts. Split body includes tail and butt parts with separable ring being squeezed between them. Peripheral diameter of reinforced part of body is larger than inner diameter of reinforced part of separable ring. Butt part is fixed on tail part with the aid of inner threaded connection. EFFECT: enhanced efficiency of drilling of large-diameter holes with rise of drilling rate and prolonged operational life. 1 cl, 2 dwg