At present, the welding system of resistance welding of intermediate frequency spot welding machine is mainly divided into four categories:
A, single-phase AC welding machine: this welding machine is the most common, the use of single-phase AC control system and transformer, can be suitable for most of the low carbon steel welding needs. However, with the control of industrial power capacity by the state, the welding of workpiece with large plate thickness will cause huge burden and impact on the power grid. The emergence of three other welding methods solves this problem.
Two, medium frequency spot welding machine: this is the most advanced welding resistance technology, it after transformer rectification, by the electrode output dc, can maximize the power factor, ensure the welding quality, and can save 30% (compared with single-phase AC). And this kind of welding machine in welding some special materials, such as aluminum, aluminum alloy, galvanized sheet, etc., the welding effect is excellent. The main technical point of this kind of welding machine is in welding controller and transformer. At present, there are also manufacturers in China to produce and manufacture, but the most mature is the welding system produced by Germany Bosch Rexroth Company. At present, the main manufacturer of this kind of welding machine is Tangshan Kaiyuan Automatic Welding Equipment Co., LTD., which uses the imported German Bosch Rexroth medium-frequency inverter welding system, but the cost is very high.
Three, three secondary rectifier welding machine: this kind of welding machine is mainly used for spot projection welding, the main feature is to achieve high power welding, and the impact on the power grid is small. Resistance welding is now also used for flash butt welding and seam welding.
Ac frequency conversion welding system: this kind of welding machine is mainly used for seam welding, the main feature is to maintain three-phase balance, small impact on the power grid, and also has the advantages of energy saving, high power factor.