| 摘要 |
The invention relates to a drilling tool and a method for down-the-hole drilling, the drilling tool being intended to drill a hole ahead of a following casing tube (13). The drilling tool comprises a central pilot drill bit (20), a reamer (33) and a guide body (12) for steering the drilling tool and casing tube relative to one another. To avoid problems with threaded connections, the guide body (12), reamer (33) and pilot drill bit (20) are mutually formed so that the rotational power is transferred from the guide body (12) to the reamer (33) and from the reamer (33) to the pilot drill bit (20), but without either of the two transfers of rotational power comprising any threaded connection, and so that an essentially radial displacement exists between the guide body (12) and the reamer (33). The construction also facilitates retraction of the reamer (33) without the pilot drill bit also needing to rotate. |
