Patent ID: 7559382

Claim:
A hard material head for a rotary percussion drill bit ( 2 , 2 ′) having an elongated shaft ( 15 ), the hard material head comprising: at least three cuffing edges ( 4 ) distributed circumferentially within a circumscribing circle ( 3 ); a bottom surface ( 6 ) located opposite the cutting edges ( 4 ) for being fastened by a material bond to an end ( 8 ) of the drill bit shaft ( 15 ) of the rotary percussion drill bit ( 2 , 2 ′); a concave side surface ( 5 ) formed circumferentially between adjacent cutting edges ( 4 ); and a peripheral pocket ( 9 , 9 ′) opening toward the bottom surface ( 6 ) and formed, respectively, in at least two concave side surfaces ( 5 ) located opposite one another, which is limited by a closing surface radially spaced from the respective concave side surface, and in which a corresponding axial pin ( 10 , 10 ′) formed on the shaft end ( 8 ) is formlockingly engageable.