Compression expansion forming system

The utility model relates to a compression-expansion forming system which comprises a hydraulic machine, the hydraulic machine comprises an upper cross beam, a middle movable beam and a workbench, the middle movable beam can move towards or away from the workbench, the compression-expansion forming system further comprises a pressurization system, and the pressurization system comprises one or more air cylinders. The air cylinder comprises a cylinder body, a piston arranged in the cylinder body and a piston rod with one end extending out of the cylinder body, the cylinder body is installed on the workbench, the end, extending out of the cylinder body, of the piston rod is connected with the middle movable beam, and a low-pressure gas inlet and a high-pressure gas outlet are formed in the cylinder body. By means of the downward pressing effect of the middle movable beam, die assembly pressure can be applied to a pipe fitting to be bulged, gas in the air cylinder can be compressed, high-pressure gas is provided