| 摘要 |
A drilling device for producing drill holes having an undercut and comprising a drilling tool including a drilling shaft, a drilling head with a drilling plate located at the free end of the drilling shaft, a stop sleeve mounted on the drilling shaft and having an opening for guiding the drilling shaft, a stop collar fixedly connected with the drilling shaft and located inside of the stop sleeve, and an annular spring for securing the stop collar in the area of an opening of the stop sleeve which is located above the guide opening.
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