What is the function of shearing and butt welding?

In the production process of spiral welded pipes, to ensure continuous production on the production line, it is necessary to weld two rolls of steel strip together to form a continuous strip. During the rolling and forming process, the head and tail sections of the steel strip do not meet the production requirements in terms of width and thickness, so it is necessary to cut off these sections before welding the two pieces of steel strip together.