| 摘要 |
The invention relates to a drill bit ( 1 ), in particular a masonry drill bit comprising an elongated shaft ( 15 ) and a cutting plate ( 2 ), one end of which has inclined cutting edges ( 3, 3';4, 4 ') that form a point. Each cutting edge ( 3, 3'; 4, 4 ') is formed by the abutment of a cutting face ( 5, 5'; 6, 6 '), lying in front of the cutting edge ( 3, 3'; 4, 4 ') in the rotational direction ( 17 ) of the drill bit ( 1 ) and a flank ( 7, 7'; 8, 8 '), lying behind the cutting edge ( 3, 3'; 4, 4 ') in the rotational direction ( 17 ) of the drill bit ( 1 ), each cutting face and flank respectively forming a wedge angle y. In the central region of the drill bit ( 1 ), the cutting plate ( 2 ) has a centring tip that is stepped in relation to the marginal regions, the cutting edges ( 4, 4 ') of said tip being set back in the rotational direction ( 17 ) in relation to the cutting edges ( 3, 3 ') of the marginal regions. The cutting edges ( 4, 4 ') of the centring tip have a cutting angle alpha ranging between 70 and 90 and a wedge angle gamma ranging between 50 and 70, at least in the immediate vicinity of said eges ( 4, 4 ').
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