| 摘要 |
<p>Drilling device for forming a borehole with an undercut, includes a cutting edge support mounted in a bearing housing so that it can rotate about an axis of rotation and pivot about a pivot axle extending transversely of the axis of rotation. A drive member via a drive shaft rotates the bearing housing and the cutting edge support. Initially, the drilling device forms a cylindrical borehole until the bearing housing contacts the material in which the borehole is formed. Then, due to relative axial displacement between the drive shaft and the bearing housing, the cutting edge support is pivoted and the cutting edges at the end of the cutting edge support within the base of the borehole makes an undercut. A stop in the bearing housing engages the cutting edge supports and limits its pivotal movement. A spring within the bearing housing returns the cutting edge support to its starting position when it is no longer pivoted to form the undercut.</p> |
