UNDERREAMER Russian patent published in 2018 - IPC E21B7/30 

FIELD: construction.

SUBSTANCE: invention relates to the field of construction and can be used to create broadening in wells for bored piles, which are mainly constructed in soft soils. Underreamer contains two coaxially disposed shafts with a sliding and fixed sleeves arranged on them on an inner shaft, to which a pantograph mechanism is hingedly attached, equipped with the elements forming the underreamer, and the stabilizers of the axial position. Both coaxially located shafts are designed to be interlocked and connected to a drill shaft of the drilling rig. Pantograph mechanism contains rock compression members arranged to form the underreamer by soil compaction by pushing the rock compression members when moving longitudinally from a hydraulic drive of an outer shaft. Rock compression members are made in the form of diametrically arranged ball segments with support brackets attached to the pantograph mechanism using bolted connections, and the shafts of the underreamer are mounted with the possibility of sequential rotation by an angle of no more than 45° clockwise with the drill shaft of the drilling rig.

EFFECT: provides an increase in the bearing capacity of the soil in the zone of underreamer and the pile itself, as well as increasing the productivity of the device.

1 cl, 8 dwg