... steel strip feeding machine, through forming rollers to curl into a steel tube, and then use high-frequency proximity effect ... 300300300OR400Of facilitiesOpen-book machines, steel butt cut, hopper, steel straightening, steel forming, high-frequency welding, to outer burr, cooling, pipe sizing, ... Forming 3.3 Seam Guide 3.4 High Frequency Induction Welding Machine 3.5 Roller System for Moving 3. ...