| 摘要 |
A spade drill bit has a shaft and a spade head portion arranged on the shaft . The head portion has a rearward facing bottom edge, two longitudinal sides and a forward faci ng cutting edge. The cutting edge has a pointed, generally triangularly shaped tip and outer ends. The longitudinal sides of the head portion are bent along a bend in a direction of rotation of the drill bit during operation, so that the outer ends are bent forwards in the rotating direction. The bend runs from a first position at one of the longitudinal sides, closer to the bottom edge than to the cutting edge, and to a second position at the cutting edge betwe en the outer end and the tip. |
