EARTH AND ROCK DRILLING

摘要

A drilling unit for the rotary drilling of bores of various diameter includes a drill-pipe string (8) with a drilling tool (9). The drill-pipe string (8) is connected to a wash swivel (3) which is connected to a drilling pump (1) and a compressor for circulating the drilling fluid. The drilling tool (9) is provided with at least two extension claws (12, 13) which are rigidly fastened to a support (14) eccentric relative to the drill pipes. The support (14) can be rotated about the drill pipes with variation of the swing and is suitable for fixing in at least two eccentric positions in which the extension claws (12, 13) are set to different bore diameters. Here, the wash swivel (3) is provided with special means for changing over from work with direct washing for producing bores of smaller diameter to work with back washing for producing bores of larger diameter.