| 摘要 |
<p>An impact operated boring tool comprising an elongated body having a forwardly tapered nose merging to a generally cylindrical housing, said tool including a generally circular array of fins projecting radially outwardly from said housing rearwardly proximate the juncture of said nose therewith and extending over a course of up to half the length of said tool along the surface of said housing. Each of said fins has a generally rectilinear cross-section throughout the major extent of the length thereof. Said fins define a series of grooves therebetween which have bottoms which are disposed at least as far from a longitudinal axis of said housing as the outer surface of said housing.</p> |
