Patent ID: 7354229
Filing Date: 2008-04-08
Classification: B23B,H05K,Y10T

Abstract:
1. A drill comprising: a chisel edge, provided at a tip end portion; a spiral first chip discharging groove and a spiral second chip discharging groove; a land portion provided between the first chip discharging groove and the second chip discharging groove; a cut blade provided at an edge of a rake surface of the first chip discharging groove, wherein the first chip discharging groove and the second chip discharging groove are provided asymmetrically with respect to a drill rotational center and a land portion, which is behind the cut blade of the first chip discharging groove, is larger than another land portion, which is in front of the cut blade of the first chip discharging groove; wherein an edge of a wall surface of the second chip discharging groove facing in a drill rotational direction does not include a cut blade anywhere along its entire length.