CROWN FOR WELL DRILLING IN EMISSION HAZARDOUS BEDS

摘要

FIELD: mining.SUBSTANCE: crown contains casing with saddle, blind axial channel with annular bore connected to the external surface of the casing by flushing ports and shutoff element mounted in the cavity of casing axial channel with radial channels connected in operating position to annular bore of the casing. The crown is equipped with shutoff element limit switch mounted at the top part of the casing. Between the limit switch and shutoff element there is a flexible element and the stroke of shutoff element is more than the distance between the bottom edge of radial channels of shutoff element and top edge of annular bore. Limit switch can be made in a form of several disks of different thickness.EFFECT: increase of crown efficiency at drilling explosion hazardous beds and increase of safety of drilling personnel.2 cl, 2 dwg