The welding circuit of the butt welding machine is main […]
The welding circuit of the butt welding machine is mainly composed of the secondary coil of the resistance welding transformer, secondary hard and soft wiring, static and dynamic fixtures, etc. Because the welding machine is welded by the heat generated by the resistance of the welding zone of the weldment, the resistance of the welding zone is micro-European.
Therefore, the welding current is usually more than a thousand amperes. Due to the large current passing through the secondary circuit, the resistance of the circuit conductor components, the contact resistance between the components, and the inductive reactance generated by the area enclosed by the secondary circuit.
When the power is turned on, a large amount of energy is lost and the power factor of the grid is reduced. The power factor of the butt welder mainly depends on the inductive reactance of the secondary circuit. The inductive reactance of the loop is almost proportional to the containment area.
In order to improve the power factor of the welding machine, the welding transformer can be made into a low leakage reactance transformer. At the same time, the containment area can be reduced as much as possible in the machine design. However, these measures have had limited effect until the advent of low-frequency welding machines and secondary rectifier welding machines. Only to solve this problem fundamentally, the power factor of the resistance welding machine was increased to 0.85-0.95.
In addition to the containment area, attention should also be paid to the material selection of the welding circuit components and the processing accuracy of the contact surface. Generally, the contact surfaces of the secondary circuit components of resistance welding machines should be finished as much as possible to reduce their contact resistance.