| 摘要 |
<p>The present invention relates to a down-the-hole drill tool, said drill tool being adapted to drill a hole in advance of a trailing casing tube (15), said drill tool including a central pilot bit (12) and a reamer means (14) and a guide means (17; 17'; 17''; 17'''; 17'''', 37) for guiding the drill tool and said casing tube (15) relative to one another, and a shaft (11; 11'; 11''; 11''') that is adapted to be connected to a down-the-hole hammer (23). The invention also relates to a guide means and a one-piece unit per se. In known drill tools of the above-mentioned type the thread connection, e.g. between the guide means and the portion supporting the reamer, is the weak point. Therefore it is an aim of the present invention to present a structural design of a drill tool of the type in question that avoids thread connections in portions of the drill tool that is subjected to high bending forces. The characterizing features of the present invention are that the shaft (11; 11'; 11''; 11''') and the pilot bit (12) is a one-piece unit and that the guide means (17; 17'; 17''; 17'''; 17'''', 37) is detachably mounted on the sahft (11; 11'; 11''; 11''').</p> |
