| 摘要 |
<p>A drill tool including a drill body having an inner insert and an outer insert at an end portion of the drill body. The distance from a central axis of the drill body to the outer insert is greater than the distance from the central axis to the inner insert. The cutting edges of the inner and outer inserts can be chamfered with the inner insert chambered at a radially inward portion and the outer insert chamfered at a radially outward portion. The inner insert and the outer insert can be mirror symmetric to one another. The inner insert and the outer insert are mounted to the drill body such that an effective cutting length of the inner insert equals an effective cutting length of the outer insert, the effective cutting lengths being measured in a direction perpendicular to the central axis.</p> |
