| 摘要 |
<p>The holder (4) for the centre drill (6) is fixed in the bore crown (1) and has at least one bolt (11) through it which goes through the wall (2) of the drill bit via at least one cavity (14,15). When locked, the holder is locked axially and or tangentially. The bolt is radially movable inside the holder and can be fixed in a defined position. The bolt is held inside the holder by means of catches (20,23,24) in the form of a pressure element such as ball (23), a detent such as annular groove (20), and compression spring (24). At least one extra fixture strut (7,8) on the holder has at least one corresponding axial, open groove (9,10) for holding the fixture strut in the wall of the bore crown.</p> |
