High pressure variable-load sealing structure

The invention discloses a high pressure variable load sealing structure, which comprises a pressing cylinder provided with a pressing cavity; a movable sealing head is installed in the pressing cavity, the front end of the movable sealing head extends into the expanding cavity of a hydraulic expanding machine to form a sealing surface; a pressure sensor I and a displacement sensor connected at the tail end of the movable sealing head are arranged in the pressing cavity; a pressure sensor II is arranged in the expanding cavity; the pressure sensor I, the pressure sensor II and the displacementsensor are electrically connected with an external controller; the controller is also electrically connected with two proportional servo valves for controlling the medium flow in the pressing cavity and the expanding cavity. The sealing structure can control the sealing surface to be provided with certain positive pressure, and ensure the expanding pressure of a pipe.