1. Steel plates can only be assembled and welded into a semicircle after a series of processing procedures by riveters or forgers.

2, riveting (forging) process is:

A) Pay-off according to the development diagram of a semicircle, blank the steel plate according to the development diagram, and cut the steel plate into the shape required by the development diagram.

B) Machining the blanking steel plate into the required semicircle curvature with a hammer or a mechanical die punch.

C) Assemble all pressed steel plates into required semicircles, weld all welds, and weld the steel plates into semicircle spheres.