| 摘要 |
The invention relates to a drill head for expanding a pilot bore in order to create a borehole having a borehole wall by removing rock surrounding the pilot bore in the region of a working face extending substantially at a right angle to the pilot bore, said drill head comprising a main body, on which a connecting element for a pilot drill string is provided, at least one tool retainer for at least one drilling tool being provided on the main body, characterised in that at least two tool retainers are provided, in that at least one tool retainer is radially spaced from the main body further than the at least one other tool retainer, such that at least one outer and one inner drilling tool are present, which can be brought into engagement with the working face, and in that the at least one inner drilling tool and the at least one outer drilling tool are each arranged in an offset manner at an angle to the working face. |
