SAETT ATT VID BERGBORRNING UTFOERA AVTAETNING MELLAN FODERROER OCH BORRHAAL JAEMTE ANORDNING FOER SAETTETS GENOMFOERANDE

摘要

The invention concerns a method and a device in rock drilling according to which a casing (1) provided with a rigid front end portion (2) is lowered concurrently with the drilling in order to seal said casing front end portion from the wall of the drilled hole. In accordance with the invention annular members (5) are inserted into one or several external peripheral grooves formed in the casing end portion (2), said annular members consisting of a material which with delay expand when moistened. Owing to this arrangement, the casing (1) may be lowered simultaneously with the drilling while encountering a minimum of resistance while at the same time a sealing means is provided which is well protected during the drilling operation but after the drilling seals the casing efficiently from the surrounding drill hole wall.