Search International and National Patent Collections

1. (WO1984002158) A METHOD EMPLOYED IN LONG-HOLE DRILLING AND A DRILL ROD SYSTEM

Pub. No.:    WO/1984/002158    International Application No.:    PCT/FI1983/000074
Publication Date: Jun 7, 1984 International Filing Date: Nov 29, 1983
IPC: E21B 17/00
E21B 17/042
E21B 21/00
Applicants:
Inventors:
Title: A METHOD EMPLOYED IN LONG-HOLE DRILLING AND A DRILL ROD SYSTEM
Abstract:
Method employed in long-hole rock drilling in which the drilling rod is made up of extension pieces which are joined to one another by a thread system. A central flushing channel is made in the extension pieces through which water or air is brought to the hole to be drilled and with the aid of which the drilled material particles are conveyed out of the drilled hole through the side flushing channel between the drill rod and the wall of the drilled hole. In accordance with the invention the steel cross-sectional surface area (Az) of the drill rod corresponding to the diameter of the hole to be drilled is selected in accordance with the power of the drilling machine to be used and thereafter the outside diameter and central flushing channel diameter of the tubular drill rod are selected so that the cross-sectional surface area (A3) of the central flushing chamber is essentially equally large as the cross-sectional surface area (A1) of the side flushing channel. A subject of the invention is also a percussive drilling arrangement to be used in the performance of the drilling method presented above. In accordance with the invention the drill rod is tubular and is manufacturd of such steel tube that the relationship of the inner diameter to the outer diameter is in the range 0.7...0.9. As a further subject of the invention is a thread system to be used in the performance of the previously presented method. In accordance with the invention the thread helix angle and form height of the threads of the screwed components of the tubular extension pieces are in the main constants independent of the outside diameter of the tube, so that the thread pitch and number of thread starts increases with the growth in outside diameter of the tube.