| 摘要 |
<p>A drill comprising a drill shank (1) having a taper portion (6) adjacent to a threaded portion (5) provided on the rear or basal portion of the shank (1). When the drill is screwed into an axial hole (h) in a drill holder (H) of a drilling machine (A), the opening edge or inner tapered wall of the axial hole (h) of the drill holder (H) bites into the taper portion (6) of the drill shank (1), consequently to bring the drill into firm connection with the drill holder (H) of the drilling machine.</p> |
