Air pipe inner diameter detection tool and detection method of tool

An air pipe inner diameter detection tool comprises a base, a long-strip-shaped groove in the front-back direction are formed in the middle of the base, a forward channel is formed in the front side of the long-strip-shaped groove, a sliding sleeve is arranged on the outer side of the base, a sliding block is arranged in the sliding sleeve, the sliding block is in sliding fit with the long-strip-shaped groove, a blocking piece is arranged on the rear side of the sliding sleeve, and a plug is arranged on the rear side of the base; a spring is arranged between the blocking piece and the plug, a lug plate is arranged on the front portion of the base, a distance sensor is arranged on the rear side of the lug plate and right faces the blocking piece, a thin metal strip is arranged on the front side of the sliding block and extends forwards to exceed the channel, two first connecting rods are hinged to the front side of the thin metal strip, and second connecting rods are hinged to the other ends of the two first c