| 摘要 |
A spade drill bit for use in association with a drill having a direction of rotation includes an elongate shank, a spade portion and a center spur. The elongate shank portion has a central longitudinal axis and one end adapted to engage the drill. The spade portion extends longitudinally from the other end of the elongate shank. The spade portion has opposed spaced apart planar faces and each planar face has a leading shoulder edge and a trailing shoulder edge. Each planar face has a leading face portion and a trailing face portion proximate to the respective leading shoulder edge and trailing shoulder edge that are twisted in the direction of rotation. The center spur extends outwardly from the spade portion along the central longitudinal axis. Preferably the center spur has an elongate flute that has a volume that increases toward the spade portion. Preferably a dimple is formed proximate to a corner leading edge which is between the leading shoulder edge and the leading longitudinal edge. |
