While-drilling sleeve device for one-time hole forming in soft coal seam

The utility model relates to a soft coal seam one-time hole-forming while-drilling casing device which comprises a multi-stage reamer bit, a blade contraction mechanism is arranged on the right surface of the multi-stage reamer bit, a rotary pipe dragging mechanism is arranged on the right surface of the blade contraction mechanism, and the blade contraction mechanism comprises a first butt joint sleeve. According to the soft coal seam one-time hole forming while-drilling sleeve device, by arranging the multi-stage hole expanding drill bit and the blade shrinking mechanism, multiple times of hole expanding can be completed through one drill bit and one-time drilling by means of the multi-stage hole expanding drill bit, disturbance to the hole wall is reduced, the hole exposure time is greatly shortened, and therefore the probability of hole collapse is greatly reduced, and the drilling efficiency is improved. If the hole wall collapses in the drilling process, the casing pipe behind the drill bit can support