Variable-diameter centralizer for air drill spraying

The invention provides a variable-diameter centralizer for air drill spraying. The variable-diameter centralizer comprises a main pipeline, a righting clamping adjustable limiting ring structure, a mounting plate, an adjustable protection frame structure, a length adjustable righting strip structure, a steel wire reinforcing strip, a middle adjustable clamping ring structure, a fixed side plate, afixing nut, an external thread adjusting rod, a rotary grip, a pipeline buffer jacking frame structure, a button battery, a display screen, a pressing plate and a pressure sensor. According to the variable-diameter centralizer, the external thread on the right end of an adjusting bolt is in threaded connection with the external thread on an external thread adjusting plate, so that the inner diameter of a locking ring is adjusted conveniently, and meanwhile, the adjusting bolt can be prevented from being clamped in a U-shaped frame; an adjusting piece sleeves a L-shaped hanging frame through hanging rings, so that the adjustment is conveniently carried out and the locking effect is conveniently achieved on the middle part of the outer side of a pipeline according to use requirements; and the left end of a pressing rod is inserted into a positioning frame and is arranged on the right side of the middle of a limiting plate in a welded mode, and a buffering spring is matched, so that theeffect of buffering and jacking the outer side of the pipeline is conveniently achieved.