| 摘要 |
<p>A rotation only core drill (1) comprising a tubular body member (2), a plurality of cutting inserts (6) brazed to a leading end of the body member and a drive spigot provided at the trailing end of the body member, wherein the cutting inserts (6) are so profiled and fitted that point contact cutting is effected, with neutral rake, wherein the inserts (6) are of hard metal with a thickness under 3 mm, typically 2 mm or less, and the wall thickness of the tubular body member (2) is ∫1.6 mm and preferably 1.2 mm or less. The invention also includes a core drill (1) provided with a detachable closure plate (15).</p> |
