UNDERREAMER OF GROUND WELLS Russian patent published in 2011 - IPC E02F5/16 E21B7/28 

FIELD: mining.

SUBSTANCE: underreamer of ground wells includes thrust rim on the housing of pneumatic puncheon and cone-shaped steel shell moving along the surface of housing of pneumatic puncheon till it touches the rim and equipped with flexible connection in the form of rope with its output to the day surface. At that, the shell is made in the form of solid ring along the side surface of which an annular recess is made. Several turns of spring wire are arranged in annular recess. At that, the dimension of recess from its upper part to lower part along the contact points with the well walls shall be maximum 50 mm and minimum 10 mm. At one point of the above recess there is a slot with closed ellipse-shaped clamp arranged in it and enclosing spring wire turns. Rope for removing the underreamer from the well is attached to the clamp. Additional slots interconnecting the inner space of recess with inner space of the well are made along the perimetre of upper horizontal surface of the ring.

EFFECT: higher operating reliability of the device, simpler design and larger area of application.

2 cl, 2 dwg