1. How to select the type of ion gas in plasma arc cutting process?
The type of ion gas determines the cutting voltage.
When the current is the same, the higher the voltage, the greater the cutting thickness and cutting speed.
When cutting thick workpieces, it is more effective to increase the cutting voltage by changing the composition of ionic gas than to increase the vigilance current.
However, it should be noted that arc extinguishing is easy when the cutting voltage exceeds 2/3 of the no-load voltage of the power supply.
Therefore, the no-load voltage of the power supply should be twice the arc voltage.
The ion gas often used for cutting is nitrogen, and the arc voltage is about 150 ~ 200V;
Nitrogen argon mixture, arc voltage about 120 ~ 200V;
Nitrogen hydrogen mixture, arc voltage about 180 ~ 300V;
Argon hydrogen mixture, arc voltage about 150 ~ 300V.
In addition, the air arc voltage is 110 ~ 150V.
Because of its low price and convenient access, it is widely used to cut the following materials.
2. Compared with plasma arc welding gun, what are the characteristics of plasma arc cutting gun?
The basic design of plasma arc cutting gun is similar to that of plasma arc welding gun.
The main differences between them are:
The channel ratio of cutting gun nozzle is much larger than that of welding gun nozzle.
The purpose of this design is to make a higher speed ion gas flame flow from the nozzle when cutting the workpiece of the gun, and use this high speed ion gas flame flow to melt the base metal and blow off the molten metal to form a notch.
Because the high-speed ion gas has a strong cooling effect on the nozzle of the cutting gun, the nozzle of the cutting gun does not need to be cooled with water, but generally the above cutting guns need to be cooled with water.
3. What are the advantages and disadvantages of plasma arc cutting compared with oxyacetylene flame and mechanical cutting?
Compared with mechanical cutting, plasma arc cutting has the advantages of large cutting thickness, flexible cutting, simple clamping of workpiece and cutting curve.
Compared with oxyacetylene flame, plasma arc has the advantages of concentrated energy, small cutting deformation and no preheating at the beginning of cutting.
The disadvantages of plasma arc cutting are: compared with mechanical cutting, plasma arc cutting has large tolerance and produces public hazards such as arc radiation, smoke and noise in the cutting process.
Compared with oxyacetylene flame, plasma arc cutting equipment is more expensive.
4. What is air plasma arc cutting? What are the characteristics of air plasma arc cutting?
Air plasma arc cutting refers to the cutting method that uses compressed air as ionic gas and uses the arc heat generated by ionization of compressed air.
Under the action of electric field, the ionized air plasma has high enthalpy, so the arc energy is large and the cutting speed is fast.
This method can not only cut non-ferrous metals such as aluminum alloy, but also cut stainless steel and carbon steel.
Moreover, this method has low cutting cost and convenient gas source. It is the most used cutting method in China at present.
5. What equipment is required for manual air plasma arc cutting?
Air plasma arc cutting is mainly composed of gas supply device, DC power supply and cutting gun.
The main equipment of the air supply unit is a 1.5 ~ 2.2kW air compressor, and the gas pressure required for cutting is 0.3 ~ 0.6MPa.
The DC power supply has the characteristics of steep drop or slow drop.
The gas source provides ion gas for the cutting gun. In order to provide ion gas for cutting with high flow rate, the outlet pressure of the gas source is much higher than that of the gas source for welding.
6 . How to select air plasma arc equipment?
The air plasma arc cutting equipment is mainly composed of gas circuit, DC current source and cutting gun.
The equipment is divided into grades according to the current. Users should select the cutting machine of corresponding grade according to the thickness of cutting plate.
The manufacturer also gives the reference value of cutting thickness in its product manual, and some data may be larger than the recommended data.
Users should note that the greater the cutting thickness of the same cutting machine, the slower the cutting speed.
The slow cutting speed not only reduces the production efficiency, but also reduces the cutting quality.
For example, there are quality problems such as cutting seam width, slag hanging on the back and so on.
If only from the perspective of improving the cutting quality, the faster the cutting speed is, the better under the condition of ensuring the cutting penetration.
7. Do cutting machines with the same current grade have the same cutting thickness?
Not necessarily the same. The cutting thickness is related not only to the current, but also to the voltage during cutting.
The cutting voltage is mainly determined by the cutting gun and cutting gas flow.
At present, there are many manufacturers producing cutting machines.
When producing cutting machines with the same current level, different manufacturers may choose different cutting guns and gas circuits, resulting in different cutting voltages.
When the current is the same, the greater the cutting voltage, the greater the cutting thickness. However, the factory instructions generally only mark the no-load voltage, not the cutting voltage. Generally, the cutting voltage of 30 ~ 100A air plasma arc cutting machine is between 110 ~ 150V.