Forging method: The end of the pipe or a department is used to punch the electric butterfly valve with a swaging machine to eliminate the outer diameter.
Roller method: a core check valve is placed in the tube, and the outer circumference is pressed by a roller for round edge processing.
Rolling method: As usual, the mandrel is not used, and it is suitable for the inner edge of the thick-walled tube.
Bulging method: one is to place rubber in the tube, and the upper part is compressed by a punch to make the tube convex and convex; the other method is hydraulic bulging forming, filling the middle of the tube with liquid, and drumming the tube into the desired shape by liquid pressure.