| 摘要 |
<p>Drilling device (90) for making undercut holes, having a drill (15), the drilling shank (19) of which has a side cutting edge (14), projecting radially beyond the periphery (18) of the drilling shank, and a flat on its periphery (18) opposite the side cutting edge (14), which flat enables the side cutting edge (14) to be inserted into the hole, and is firmly connected to an articulated connecting coupling (20) which permits wobbling shank movements during the rotation of the drill (15), is arranged between the drill (15) and a drill drive and has a coupling piece (28) on the drill-drive side with an axially movable pressure body (85) which can be supported on an inclined surface (17) of a coupling piece (29) connected to the drilling shank (19), which inclined surface (17) effects a radial advance of the side cutting edge (14). In order to improve a drilling device (90) having the features mentioned at the beginning in such a way that the drill (15) can be positively guided against radial movements when the pilot hole (12) is being made in the workpiece (46) by axial feed of the drill (15) or can be pulled out of the completed undercut hole even if self-alignment, effected by centrifugal force, of the coupling piece (29) on the drilling-shank side is not possible or is not possible to an adequate degree, this device is designed in such a way that the pressure body (85) axially overlaps the coupling piece (29) on the drilling-shank side in a position not acted upon axially and is radially coupled in a positive-locking manner to this coupling piece (29). <IMAGE></p> |
