Slim-hole hydraulic controlled reducing reaming bit

Slimhole one kind of controllable adjustable hydraulic reaming bit. The main difference between the solution prior gage reaming bit performance, the problem is difficult to retract the tool body. Characterized in that: a pilot bit (1) is connected to the upper end of the body (2), the pilot bit (1) the aqueous eye ball valve upper seat (3), the ball valve (3) of the stem (4) has a diameter lower step ferrule to (5), the connection sleeve (5) with the upper end of the main body through the connecting flow channel is connected to a hollow sleeve (2) of the piston (6), the body (2) wall of the hole on both sides of three elongated inclined chute built-in blade (8), the piston (6) and the cutter body (8) at the lower end of the corresponding eyes of water (9), blade (8) in contact with the piston (6). The reaming bit having a diameter of good retention properties, blade retracted reliable, long life characteristics.