pipes used in drill holes for the lowering and raising of rock-crushing tools, the transmission of rotation, the creation of an axial load on the tool, and the supply of flushing fluid or compressed air to the mine face. A distinction is made among conventional, heavy, and drive drill pipes.
Conventional drill pipes are seamless and are made of steel or aluminum alloys of round cross section, with a wall thickness of 4.75-11 mm, which are coupled by drilling wrenches or semicouplers with a special coarse taper thread. Drill pipes are thickened at the ends for greater strength. Heavy drill pipes are made of steel with a round or square cross section, with a wall thickness of 16-50 mm and higher; they are also coupled by threads and serve to increase the rigidity of the lower compressed portion of the column and to create a load on the rock-crushing tool. The drive drill pipe, which has a polyhedral cross section, is located at the top of the column and transmits the rotation from the rotary table of the drilling rig to the column.
Drill-pipe improvements have resulted in increased strength, durability, and tightness of threaded joints, decreased hydraulic resistance of the sink hole, and a reduction in mass.
REFERENCESIl’skii, A. L., V. M. Kas’ianov, and V. G. Poroshin. Burovye mashiny, mekhanizmy i sooruzheniia. Moscow, 1967.
S. A. VOLKOV and E. M. SOLOV’EV