| 摘要 |
The present invention relates to a drill tool for rotary and/or percussive drilling comprising a drill head (10;10 sec ) including a pilot means (11;11 sec ) and a reamer means (12;12 sec ) located behind the pilot means (11;11 sec ) seen in the feed direction of the tool, guide means (16;16 min ;16 sec ;16''') to guide said drill tool relative to a casing tube (15;15 min ) surrounding said guide means (16;16 min ;16 sec ;16'''), and cooperating driving means (18,19) on the guide means (16;16 min ;16 sec ;16''') and the casing tube (15;15 min ), respectively, for downwards axial displacement of the casing tube (15;15 min ), and means for connecting said drill tool to a hammer drilling equipment. The invention also relates to a casing tube and a guide means per se. When drilling through an overburden by a drill tool of the type specified above it quite often happens that the casing tube get stuck by wedge action from loose rock segments or by a sucking action, especially when the overburden consists of clay. The present invention is characterized in that the casing tube (15;15 min ) is rotated by cooperating driving means on the guide means (16;16 min ;16 sec ;16''') and the casing tube (15;15 min ). |
