Multi-pipe-diameter single hydraulic top drive back-up wrench and clamping technology thereof

The invention relates to a multi-pipe-diameter single hydraulic top drive back-up wrench and the clamping technology thereof. According to the technical scheme, a lever is arranged on a back-up wrench body through a shaft, the lever comprises a lever left end, a lever rod, a constraint belt and a tooth block, a hydraulic power part comprises a hydraulic cylinder, a hydraulic piston rod and an arc hoof piece, the lower end of the hydraulic piston rod penetrates through a reserved hole in the back-up wrench body and is then provided with the arc hoof piece, so that the arc hoof piece is placed right above the lever left end, when the hydraulic piston rod goes down, the arc hoof piece is in contact with the lever left end, the lever left end is pushed to move downwards, the whole lever rotates around the shaft, and the lower end of the lever pushes a drill rod to move rightwards. The multi-pipe-diameter single hydraulic top drive back-up wrench has the advantages that fault rate is low, service life is long, the structure is simple, weight is light, and manufacturing cost is low. The drill rod wrapping angle is large, a certain round-setting effect can be achieved on the clamped drill rod, and screwing off on the drill rod with certain deformation is smooth. Flexile clamping and rigid clamping are used in a clamping part, tightening of different pipe diameters can be achieved flexibly, and clamping performance is good.