| 摘要 |
FIELD: mining. ^ SUBSTANCE: bit is divided into stages - an under-reaming one with a tail and a stabiliser and a lower spudding one one with a stabiliser, every of which is made in the form of independent solids of revolution arranged coaxially, at the same time cutting speeds of cutting elements of under-reaming and spudding stages that are most remote from the longitudinal axis do not exceed critical values, besides, stabilisers equipped with highly resistant rods, have calibrating effect. ^ EFFECT: improved wear resistance and running time of a bit in interbedding rocks, including alternations of VI-IX categories by drillability, with preservation of borehole verticality. ^ 2 dwg |
