1. Forging method, the end or part of the pipe is punched with a swage forging machine to reduce the outer diameter. Common swage forging machines include rotary, connecting rod, and roller types. 　　

2. Punching method, using a tapered core on the punch to expand the pipe end to the required size and shape. 　　

3. Roller method, in which a core is placed in the tube, and the outer circumference is pushed by a roller for round edge processing. 　　

4. The rolling method generally does not require a mandrel, and is suitable for the inner round edge of the thick-walled tube.

5. Zigzag forming method, there are three more commonly used methods, one method is called expansion method, another method is called stamping method, the third method of rollers, there are 3-4 rollers, two fixed rollers, one adjusting roller, adjustment With a fixed roll distance, the finished pipe will be zigzag.

6. The bulging method, one is to place rubber in the tube and compress it with a punch on the top to make the tube protrude into shape; the other method is hydraulic bulging, filling the middle of the tube with liquid, and the liquid pressure bulges the tube to the required size The shape, most of the production of corrugated pipes use this method.