| 摘要 |
The invention relates to a drilling device that is meant to be used in a down-the-hole drilling apparatus for drilling a hole by using the drilling device (1) and a casing part (2) as well as a hammering device when needed. The drilling device (1) comprises in a drilling head (I) thereof a guide (4), drilling means (5) and as well as advantageosly flushing means for flushing of drilling waste being generated. The drilling means (4) comprise a first drill bit arrangement (5a) and a second drilling bit arrangement (5b) that is movable with respect to the above and that is arranged on the one hand to be expanded for drilling a greater (t) hole than the free cross-sectional surface area of an end (Ι') of the casing part (2) and on the other hand to be reduced to a smaller size than the free end (Ι') of the casing part. The bit pieces (5bl) of the second drill bit arrangement (5b) are arranged, for expanding/reducing of the second drill bit arrangement (5b) by means of the guide (4), movable in slide grooves (U) that pass wide open in the radial direction (r) on a drilling surface (P) of the drilling means (5) for expanding the second drill bit arrangement (5b) by moving its bit pieces (5bl) in the radial direction (r) outwards in the slide grooves (U), by rotating (w) the guide (4) in a drilling direction, and for reducing the second drill bit arrangement (5b) by moving its bit pieces (5bl) in the radial direction inwards in the slide grooves (U), by rotating the guide (4) in an opposite direction. |
