Forging method: The end or part of the pipe is stretched by a forging machine to reduce the outer diameter. The commonly used forging machines are rotary, connecting rod and roller.
Stamping: The end of the pipe is extended to the required size and shape with a tapered core on the punch press.
Roller method: Core is placed in the tube, and roller is used to push the edge.
Rolling method: generally no mandrel, suitable for thick-walled tube inside and outside the circular edge.
Bending forming method: There are three common methods, one is called stretching method, the other is stamping method, the third is the familiar rolling wheel method, there are 3-4 rollers, two fixed rollers, one adjusting roll, adjusting the fixed roll distance, the finished pipe is bent. This method is widely used. If spiral pipe is produced, the curvature can be increased.
Bulging method: one is to place rubber in the tube and compress it with a punch on the top to make the tube protrude; the other is to form the tube by hydraulic bulging, filling the liquid in the middle of the tube and bubbling the tube into the desired shape by the liquid pressure. This method is mostly used in our common bellows production.