High frequency welding is divided into induction welding and contact welding according to the contact with the pipe. Compared with induction welding, contact welding can improve the efficiency by 50%, but the contacts need to be replaced frequently, and the pipe must be well formed, otherwise it is easy to spark, and the weld is prone to scratches. Especially disadvantageous is that there will be Copper remains. Welded pipes are prone to corrosion after a long time. The quality of the induction welding seam is good, but the welding machine power of the welded pipe of the same specification is nearly doubled. Equipment investment is 50% ~ 55% higher.
The high frequency welding machine is divided into two types: vacuum tube type and solid state type (transistor). The solid state type has a smaller size and higher efficiency (15% higher) than the vacuum tube type, but its reliability and maintainability are not as good as the vacuum tube type. The vacuum tube is also 15% higher than the price. The new large-size cold-formed rectangular rectangular pipe production line basically uses solid-state high-frequency welding machines. The current solid-state high-frequency welding machine technology is developing rapidly. For example, the famous EFD high-frequency welding machine has the following latest technical features:
EFD high-frequency welding machine uses a new and unique WELDAC G2 electronic matching system to make its energy conversion rate as high as 85% to 87%. Due to the use of diode rectification technology, its power factor can be constant to 0.95, without the need for power factor make up. Frequency range: 50 ～ 500kMz. It adopts an independent frequency conversion module design. The rectifier and the frequency converter are connected by a long cable, which can continuously match different loads. It has the characteristics of high efficiency, energy saving and low operating cost. The new 200mm × 200mm ～ 450mm × 450mm / 500mm × 200mm rectangular tube production line of Baosteel Iron and Steel Technology Research Institute has selected EFD high frequency induction (maximum induction welding power 700kW) and contact welding dual function welding machines.