DEVICE FOR CREATING AXIAL LOAD ON DRILLING BIT Russian patent published in 1998 - IPC

FIELD: bore-hole drilling technology. SUBSTANCE: this relates to bottom-hole devices intended for creating axial load on drilling bit. Device has hollow spindle which is provided with means for its connection to drilling string and drilling bit. Spindle is made up of upper part and lower part connected to each other by splined joint which holds them from relative turning. Formed inside upper part of spindle are power cylinders and located inside power cylinders are pistons made on external surface of spindle lower part. Installed on upper part of spindle above power cylinders with possibility of rotation relative to spindle upper part is hydraulic anchor which in combination with spindle creates hydraulic chamber. Hydraulic chamber through its holes and head-pieces is connected with annular space. Hydraulic anchor is provided with extending supporting members installed in radial holes of body. Bore is made inside upper part of spindle above power cylinders. Seated in aforesaid bore is control valve made in the form of stepped bush with radial holes. Bush is spring-biased relative to upper part of spindle. Stepped bush underneath has spring catches which can interact with fixing step made inside upper part of spindle above power cylinders. Lower part of spindle above pistons has tail-piece. Section of external surface of tail-piece is turned on lathe. Length of this section is equal to working stroke of pistons. Locking ring is seated on aforesaid section and it is movable in axial direction. Locking ring can interact with lower parts of spring-biased catches of control valve. Hydraulic chamber of anchor and working spaces of power cylinders are connected with internal space of device and annular space through radial holes made in spindle wall. EFFECT: higher efficiency. 4 cl, 3 dwg