The principle of plasma cutting is: arc discharge is performed between the base material (including the nozzle in the torch) and the electrode in the torch, and the discharge heat is used to generate a high-temperature, high-speed plasma arc from the compressed gas to fuse the base material.
Features of air plasma cutting: Easy to cut all metals, fast cutting speed
The cutting deformation is small, and the cutting can be realized without a fixed clamp. The cutting shape is not restricted and the heat-affected area is small.
Both contact and non-contact cutting are not required, and the operation is simple.
Widely used in industrial production, especially the welding of copper and copper alloys, titanium and titanium alloys, alloy steels, stainless steel, molybdenum and other metals used in military and cutting-edge industrial technologies such as aerospace, etc., such as titanium alloy missile shells and spacecraft Some thin-walled containers, etc.
Types of plasma arc
According to the different power connection methods, plasma arc has three forms: non-transferred, transferable and combined
(1) The non-transferred plasma arc tungsten electrode is connected to the negative end of the power supply, and the nozzle is connected to the positive end of the power supply. The plasma arc body is generated between the tungsten electrode and the nozzle. Under the pressure of plasma gas, the arc column is ejected from the nozzle to form plasma flame.
(2) Transfer type plasma arc: The tungsten electrode is connected to the negative end of the current, and the weldment is connected to the positive end of the current. The plasma arc is generated between the tungsten electrode and the weldment. Because the transfer arc can transfer more heat to the weldment, metal welding and cutting almost all use the transfer plasma arc.
(3) Combined plasma arc When working, non-transferred arc and transferred arc coexist at the same time, so it is called combined plasma arc. The non-transferred arc plays the role of stabilizing the arc and supplementary heating, and the transfer arc directly heats the weldment to melt it for welding. Mainly used for micro-beam plasma arc welding and powder overlay welding.
Transfer plasma arc
In order to establish a transfer plasma arc, the tungsten electrode should be connected to the negative electrode of the power supply, and the nozzle and the weldment should be connected to the positive electrode at the same time. The transfer type arc first connects the circuit between the tungsten electrode and the nozzle, ignites the arc between the tungsten electrode and the nozzle, and then Quickly connect the circuit between the tungsten electrode and the weldment, so that the arc is transferred to the tungsten electrode and the weldment for direct combustion, and the circuit between the tungsten electrode and the nozzle is cut off at the same time
Under normal working conditions, the nozzle is not charged, and the plasma arc generated at the beginning of ignition is only used as an intermediate medium for establishing the transfer arc.
