| 摘要 |
<p>Improved cutter elements for drill bits of the type having two to four conical-shaped cutters mounted in a supporting body for rotation about their respective axes with their apices inclined downwardly-inwardly toward the axis of rotation of the body; the cutter elements are spaced apart from one another both axially and circumferentially of the substantially conical exterior of each conical-shaped cutter and, usually, disposed in spaced circumferential rows, each cutter element including a pair of interacting chisel or wedge-shaped teeth intersecting each other --preferably at their medial portions in perpendicular relationship-- coextensive from crest to root and having their respective crests extending approximately radially of the axis of rotation of said cutter and generally circumferentially of said cutter axis; the circumferentially- oriented teeth have coextensive cutting edges at their ends and are adapted to cut through ridges created in the formation by the radially-oriented teeth and laterally displace cuttings of the latter as well as contact said formation ahead or prior thereto so as to permit greater penetration of said radially-oriented teeth. Both teeth of each cutter element may be of relatively narrow transverse dimensions or thickness as well as minimum taper, such as 40.degree. or less, and the circumferential spacing between adjacent cutter elements may be relatively wide without unduly weakening said teeth, whereby a drill bit having such cutter elements may be utilized in varying formations, from relatively soft to relatively hard, so as to minimize the necessity of replacing the bit before exhauston of its usefulness.</p> |
