1. The circular thin plate is first pressed into a half waveform ring plate by circular ring welding, and then connected with a circumferential seam at the wave crest and wave trough. Domestic heat exchangers use pneumatic ball valves, which are made in this way. The wall thickness at the wave crest increases due to compression during stamping, and decreases due to tension at the wave trough. In order to improve the stress condition of circumferential seam during welding of pneumatic ball valve, a small straight edge can be added at the corner of the disc.
2. The cylinder is expanded and formed on a cylinder with only longitudinal welds, and the local circumferential expansion of the cylinder is wavy by hydraulic pressure, valve die or forming roller and other local extrusion methods. Pneumatic ball valves are often used for the mass production of small diameter pipes for pipes and instruments. The wall thickness of the protruding part of the Bowen pipe made by this process is smaller than that of the mesh cylinder.
3. The rolling plate is formed by first forming the flat plate into a plate, then rolling the plate vertically into a cylinder, and then connecting it with a longitudinal weld. It is suitable for pneumatic ball valves with small waveform and large cylinder diameter. The single wave lath is rolled into a ring and then welded, or the pneumatic ball valve plate is directly pressed into a brush shaped block of energy waves, and then the longitudinal seam is used to make a circle.