Thrust auxiliary reamer bit

The invention relates to a thrust auxiliary reamer bit which comprises a drill rod (1), a multi-blade reamer (2) which is connected to a forcing device (4) and a cylinder (5) to form a whole, and a drill bit (3), all the parts being connected in sequence. The invention is characterized in that the forcing device (4) is a fluid piston type and formed by the cylinder (5), a piston (6) and a piston rod (1) arranged in the cylinder, the piston (6) is fixed on one end of the piston rod (7), the other end projects the cylinder (5) and fixes a taper forcing head (10); an air channel is arranged in a wall of the cylinder, an upper chamber air inlet/exhaust hole (11) at one end of the air channel is through in the piston chamber, an open at the other end is communicated with a Cornish bit wing air passage namely a drill rod air channel, a lower chamber air inlet hole (13) is arranged on the wall of the cylinder and is communicated with outside through the wall of the cylinder; and a reset spring (9) is sleeved on the