Rigidity-variable intermediate support device

The utility model discloses a middle support device with variable rigidity. The middle support device comprises an inner retainer, an outer retainer, a shell, a curved bag and a bearing, the inner retainer is arranged in the outer retainer, the outer retainer is arranged in the shell, and the inner retainer, the outer retainer and the shell are coaxially arranged; the plurality of bearings are uniformly distributed and arranged on the inner side of the inner retainer in a surrounding manner by taking the center of the inner retainer as a circle center; the curved bags are flexible parts of an annular structure, the upper end and the lower end of the outer retainer are connected with the outer side of the inner retainer through the curved bags respectively, and an air cavity is defined by the two curved bags, the inner retainer and the outer retainer. The air cavity is connected with an air conveying device, the air conveying device is used for filling the air cavity with high-pressure air, and the rigidity of