The main component of the welding machine is a buck transformer, the two ends of the secondary coil is welded workpiece and welding rod, working when the ignition arc, in the high temperature of the arc welding electrode weld in the gap of the workpiece.
Because the iron core of the welded transformer has its own characteristics, it has the characteristic of a sharp drop of voltage, that is, the voltage drops after the welding of the electrode, and the voltage drops sharply when the electrode is short-circuited by adhesion. During welding operations, although the current in the circuit is equal, but because the resistance is different everywhere, the resistance at the fixed contact is the largest (this resistance is called contact resistance), according to the law of thermal effect of the current (also known as the Law of Joule), that is, Q=irt: When the current is equal, the greater the resistance of the area, , the contact of the electrode is the contact resistance of the connected metal body is the most, then in this part of the heat generated by the most natural, coupled with the electrode is a lower melting point of the alloy, naturally easy to melt.
The melted alloy electrode core is glued to the welded object, and when cooled, the welded object is glued together. The General DC inverter Welding Machine panel is equipped with an output DC current adjustment knob.
Inverter DC Welding Machine will first single-phase AC 220V voltage or three-phase AC 380v Voltage Bridge rectifier, filter, and then supply power switch devices for inverter processing. A small number of inverter welding machine first uses 555 time base circuit and other pulse generation circuit to produce rectangular pulse wave, and then use transistor for current amplification, and then use a pair of complementary field effect tube for voltage amplification, resulting in high-frequency signal, and finally the use of booster transformer for boost, in two windings to obtain inductive alternating current.
The size of its power depends on the magnification of the amplifier circuit. Inverter welding machine mostly uses IGBT tube to form a single-correct excitation inverter circuit, its control system uses pulse width modulation chip SG3525, its inverter frequency is 20kHz, and can carry out constant current characteristics control. When the system is empty, due to the use of voltage feedback control, PWM modulator discontinuous output pulse, because the frequency of intermittent oscillation is low and pulse width is narrow, so not only the load loss is small, and the transformer is not easy to saturation. Because the welding machine adopts the control technology with pulse width modulation PWM as the core, it can obtain better constant current characteristics and excellent welding process effect.
