| 摘要 |
A drill 10 comprising a cutting head 12 releasably mounted on a forward end of a toll shank 14, having a common axis of rotation defining a direction of rotation, the cutting head 12 comprising a head surface, a head base surface and a peripheral side surface extending there between, the head base surface being transverse to the axis of rotation, the fixation portion protruding rearwardly from the head base surface away from the head surface and comprising a head fixation surface extending circumferentially relative to the axis of rotation; at least two head flutes extending along a periphery of the cap and fixation portions forming identical head segments between adjacent pairs of head flutes, each head segment comprising a cap recess opening out of the side surface and the head base surface and dividing the head base surface into first and second head base surfaces, a head torque transmission wall 52 extending along a portion of the cap recess transverse to the head base surface and generally facing opposite the direction of rotation, a head fixation recess dividing the head fixation surface into first and second head fixation surfaces; at least two shank flutes extend along a periphery of the tool shank 14 forming identical shank coupling portions between adjacent pairs of shank flutes at the forward end of the tool shank 14, each shank coupling portion comprising a forwardly facing shank support surface and a shank fixation surface located axially rearwardly relative to the shank support surface, a shank fixation recess divides the shank fixation surface into first and second shank fixation surfaces; a protuberance protrudes forwardly from each shank support surface, the protuberance dividing the shank support surface into first and second shank support surfaces, a shank torque transmission wall 82 extending along a portion of the protuberance transverse to the shank support surface and generally facing the direction of rotation; wherein pairs of head segments and shank coupling portions are in mating relationship, and wherein for each such pair the first head base surface 46 abuts the first shank support surface 76, the second head base surface 48 abuts the second shank support surface 78, the head torque transmission wall 52 abuts the shank torque transmission wall 82, the first head fixation surface abuts the first shank fixation surface and the second head fixation surface abuts the second shank fixation surface . |
