| 摘要 |
A device, for cutting an undercut in a borehole at a location spaced from the surface of a material into which the borehole is formed, includes a housing (1) with a bore therethrough and a guide sleeve (2) rotatably supported in the housing bore and having an eccentric bore therein. A bushing (3) with an eccentric bore is rotatably supported in the guide sleeve bore. A drive shaft (7) is rotatably supported in and extends through the eccentric bore of the housing and has a cutter head (9) at one end. The drive shaft (7) can be shifted from a centered position within the housing bore into an eccentric position by rotation of the bushing (3) relative to the guide sleeve (2). In the eccentric position, the cutter head (9) can penetrate into and form an undercut in the surface of the borehole. A displacable snap-in element (16) in the housing (1) prevents rotation of the guide sleeve (2). When the maximum eccentricity of the drive shaft (7) is reached, the snap-in element is disengaged from the guide sleeve by an actuating cam (3a) on the bushing (3). Subsequently, the guide sleeve (2) and the bushing (3) can be rotated together through at least 360 DEG degrees for cutting the undercut. A blocking member (13) prevents rotation of the guide sleeve (2) during rotation of the bushing back into the center position.
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