Telescopic back ridge at external corner part of wall body

The utility model discloses a telescopic back arris at the external corner part of a wall body, which relates to the technical field of building construction and comprises two hinged back arris bodies, the two back arris bodies are connected through an external corner connecting piece, each back arris body comprises a plurality of square tubes, every two adjacent square tubes are connected through a back arris connecting piece, each back arris connecting piece comprises a U-shaped connecting piece, the side wall of each U-shaped connecting piece is arranged upwards, and the side wall of each U-shaped connecting piece is arranged upwards. The two ends of the top of the U-shaped connecting piece are each provided with a plurality of bolts in a sliding mode, the U-shaped connecting piece is further provided with a first elastic mechanism for driving the bolts to descend, and the square pipes are provided with inserting holes for the bolts to be inserted in, so that the multiple square pipes can be connected thro