SCREW DRILL FOR FORMATION OF WELLS IN FROZEN SOILS Russian patent published in 2020 - IPC E21B7/00 E21B10/44 

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to excavation works, in particular, to devices for formation of wells. Screw drill for formation of wells in frozen soils contains conical core with helical blade, which consists of conical section with constant pitch of blade turns and cylindrical section with pitch of blade turns, which has constant increment relative to step of turns of conical section of blade. Helical blade has the same number of turns on the cylindrical and conical sections, equal to not more than two. Diameter of the turn of the blade on the cylindrical section is more than twice the diameter of the base of the cone described by the edge of the turns of the blade of the conic section. Conical section is located at an angle relative to rotation axis of bore and is connected with cylindrical section by means of carrier and bearing assembly arranged inside conical section.

EFFECT: creation of different rotation frequencies on cylindrical and conical sections.

1 cl, 1 ex, 1 dwg