... Thickness : 0.28 0.32 4.Speed: 30-100M/min 5.CE High Frequency Aluminium Pipe making machineDevice principle: high-frequency welding steel ... to curl into a steel tube, and then use high-frequency proximity effect and skin effect heating the tube side ... machines, steel butt cut, hopper, steel straightening, steel forming, high-frequency welding, to outer burr, cooling, pipe sizing, pipe straightening, ...