Resistance welding is to clamp the work piece between two electrodes and apply a current. The current is heated to a molten or plastic state through a resistance heating effect flowing through the contact surface of the workpiece and the current in the adjacent region to form a metal. A combination of methods. The welded pipe made of resistance welding is called the resistance welded pipe (ERW pipe).
ERW pipe machine
The efficiency of ERW pipe welding machine is 3 to 5 times higher than that of traditional TIG welding. Due to frequent defects such as incomplete penetration of roots and sag of arc, MIG welding filler and sealing process are welded by TIG. Although the improved welding technology basically solves the problem of incomplete penetration of root, the welding efficiency is reduced. The investment in equipment is increasing, but the operation process is also complex.
The principle of hot wire TIG welding is to provide independent constant voltage AC power for filling wire before filling the welding wire into the molten pool. When the resistance is heated to a temperature of 650 ~ 800 degrees, the melting speed of the welding wire is greatly accelerated, and the film forming speed is close to the MTG welding speed of the same diameter. In addition, the good return feature of the TIG method ensures the quality of the backing weld. Therefore, hot wire TIG welding is the preferred welding method for butt welding of small diameter wall thickness pipes. However, the feasibility of using pulsed MIG welding to join small diameter thick walled tubes should not be totally rejected. Many tests have been carried out to find that over 90% of the roots penetrated in the super arc in the butt joint of the thick wall tube MIG welding, and the sag of the arc pits was the heat accumulation in the continuous multi-layer welding process caused by the overheating of the pool metal if the accurate control of the arc power of the welding power supply could be completely eliminated. The above defects can be eliminated. However, because the original welding power source of the imported MIG welding automatic pipe welder is the thyristor pulse power supply, it is unable to realize the program control of the arc power supply, such as switching to the most advanced full digital all digital control inverter pulse welding power or waveform control pulse welding power source (microcomputer control software), welding arc can be based on welding. The process requirements are easily controlled to ensure welding quality.