Patent ID: 7393162

Claim:
A gun-drill having a longitudinal axis of rotation A defining a front-to-rear direction and a direction of rotation R, and comprising a cutting head detachably secured to a shank; the cutting head comprising a cutting portion adjacent a cutting-head forward end and a cutting-head coupling portion adjacent a cutting-head rear end, the cutting-head coupling portion comprising an axially rearwardly facing cutting-head support surface and a generally frustoconical cutting-head fixation surface tapering radially inwardly while extending forwardly towards the cutting-head cutting portion; the shank comprising a shank coupling portion formed at a shank forward end, the shank coupling portion comprising an axially forwardly facing shank support surface and a generally frustoconical shank fixation surface tapering radially inwardly while extending forwardly towards the shank forward end; wherein the cutting-head fixation surface extends peripherally continuously from a cutting-head flute leading face to a cutting-head flute trailing face over a cutting-head peripheral angle φC greater than 180°; and the shank fixation surface extends peripherally continuously from a shank flute leading face to a shank flute trailing face over a shank peripheral angle φS greater than 180°; in a secured position, the cutting-head coupling portion and the shank coupling portion interlock co-axially, with the cutting-head support surface abutting the shank support surface; and cutting head and shank peripheral surfaces and cutting-head and shank flute leading and trailing faces mate and are co-aligned.