| 摘要 |
The drill line for drilling wells at strike-dangerous coal beds has borer and reamers. Diameter of the cutter of the borer is taken minimal (50 mm), the borer with length not less than 1200 mm is conical in shape with diameter gradually varying from the cutter to the tail element from 50 to 100 mm. The reamers that follow it are made removable, those are different in diameter not exceeding, respectively, the dimensions of the zones of unloading with respect to the preliminary widening of sections of the well, with placement at drill beam in sequence of increase of diameters of those through intervals S determined from the formula: S=Vtcr, m, where V û rate of drilling the well, m/min; tcr û time needed for stabilization of tensions in the coal bulk, min. The utility model increases safety and productivity of drilling wells with large diameters.
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