Combined type detachable inner supporting and tightening device for box sealing based on slope reinforcement

The invention belongs to the technical field of friction stir welding of circular seams of carrier rocket storage tank bodies, and particularly relates to a combined box sealing detachable inner supporting and tightening device based on slope reinforcement. Comprising a lower-layer lifting seat assembly, an upper-layer supporting disc assembly and a personnel operation platform assembly, and during box sealing welding, the personnel operation platform assembly is assembled and fixed in the box bottom; after box sealing welding is completed, the upper-layer supporting disc assembly is detached and then moved out of the box through a side face manhole of the box bottom assembly, and the personnel operation platform assembly is detached and then moved out of the box. When the butt joint circular seam of the box bottom and the cylinder section is welded, the fork-shaped ring of the bowl-shaped box bottom and the lower edge of the adjacent cylinder section are supported into a circle, enough supporting force is pr