| 摘要 |
<p>A method and apparatus for down-the-hole drilling. The drilling is carried out by a drilling device including a casing and a drilling unit. The drilling head includes a first drill for drilling a center hole, a second drill for reaming the center hole and a flushing flow arrangement including a first flusher for leading a flushing medium onto a drilling surface and a second flusher for returning of the flushing medium and drilling waste inside the casing. The first drill is removably coupled with the second drill to enable removal thereof from the hole. The casing is arranged to be drawn into a hole to be drilled by the drilling unit. The flushing medium is brought onto the drilling surface and returned therefrom by axially directed flow arrangements disposed in a cross-section view on an outer periphery of the first drill and/or in an inner periphery of the second drill.</p> |
