Patent ID: 7497282

Claim:
A drill bit for use on a hammer drill comprising: a drilling head ( 2 ) formed entirely of a hard material as a single-piece body with radial legs ( 18 , 19 ) and having at least three radially extending cutting bits ( 5 ) formed on the radial legs ( 18 , 19 ) of the hard material body adapted for use in operation on the hammer drill, with the radially extending cutting bits ( 5 ) being wedge-shaped in a radial direction with at least two of the radially extending cutting bits ( 5 ) having radially extending cutting edges; and a centering tip ( 11 , 21 ) provided in a center of the hard material single-piece body and projecting beyond one of the cutting bits ( 16 , 17 ), the centering tip ( 11 , 21 ) having linearly extending auxiliary cutting edges ( 13 , 23 , 24 ) and concave limiting surfaces ( 12 , 22 ) stretching between the auxiliary cutting edges ( 13 , 23 , 24 ) adapted for use in operation on the hammer drill; wherein a wedge angle (α) of the linearly extending, auxiliary cutting edges ( 13 , 23 , 24 ) is smaller than a wedge angle (β) of the wedge-shaped cutting bits ( 5 ).