1. Folding method: Fold the steel plate to be welded in a radian way, or bend it into an arc with a bender, then turn the two ends of the arc steel plate upside down and fix it with a fixture before welding.

2. Hot pressing method: the flat steel plate is heated and compressed into an arc, and then welded and fixed. This method needs professional equipment and tools to complete, which can improve the radian accuracy and welding quality to a certain extent.

3. Arc rolling method: the steel plate is rolled into a smooth arc surface with a professional arc rolling machine, and then the rolled steel plate is welded and fixed.