FORFARANDE VID BERGBORRNING MEDELST EN STRENG AV SKARVADE BORRSTENGER SOM FORES GENOM ETT BORRSTOD UNDER BORTSUGNING AV KAX UR DETTA OCH ANORDNING FOR GENOMFORANDE AV FORFARANDET

摘要

A method and apparatus for guiding and sealing a drill string during drilling. The drill string is formed with an increased diameter at the portions where two adjacent rods are connected. The guiding and sealing of the rods is maintained by means of hydraulically operated guide jaws in a drill rod centralizer. The increased diameter portions are guided and sealed by means of tubular members located rearwardly and forwardly of said jaws. The drill rod centralizer is mounted on a saddle which is slidable along a feed bar. The drill rod centralizer is connected to means for removing drill dust and may be provided with a tubular portion for guiding the drill bit during collaring of a new hole.