The main points of plasma arc cutting

Update:25 Feb 2021

Plasma arc cutting is the use of high-temperature plasm […]

Plasma arc cutting is the use of high-temperature plasma arc heat to make the metal part or local melting (and steaming) at the incision of the workpiece.
Hair), and use the momentum of high-speed plasma to remove molten metal to form a processing method of incision. Plasma arc cutting machine
(Plasma Cutting Machine) is a machine that uses plasma cutting technology to process metal materials.
One. Industrial use
Plasma cutting with different working gases can cut all kinds of metals that are difficult to cut by oxygen-acetylene cutting, especially for
For non-ferrous metals (stainless steel, aluminum, copper, titanium, nickel), the cutting effect is better, and its main advantage is that the thickness of gold is not large.
The plasma cutting speed is fast, especially when cutting ordinary carbon steel thin plates, the speed can reach 5~ that of the oxygen-acetylene cutting method.
6 times, the cutting surface is smooth, the thermal deformation is small, and the heat-affected zone is less.
Plasma cutting machines are widely used in automobiles, locomotives, pressure vessels, chemical machinery, nuclear industry, general machinery, engineering
Machinery, steel structure, shipbuilding and other industries.
Two. Working gas
The current development of plasma cutting, the available working gas (working gas is the conductive medium of the plasma arc, but also the carrier
Hot body, and also to eliminate the molten metal in the incision) has a clear understanding of the cutting characteristics, cutting quality and speed of the plasma arc.
Significant impact. Commonly used plasma arc working gases are argon, hydrogen, nitrogen, oxygen, air, water vapor and some mixed gases.
Three, cutting specifications
Various plasma arc cutting process parameters directly affect the stability, cutting quality and effect of the cutting process. Main cut
The specification is briefly described as follows:
1. No-load voltage and arc column voltage
The plasma cutting power supply must have a high enough no-load voltage to easily start the arc and make the plasma arc burn stably.
The no-load voltage is generally 120~600V, and the arc column voltage is generally half of the no-load voltage. Increasing the arc column voltage can significantly
Increasing the power of the plasma arc can increase the cutting speed and cut larger thickness metal plates. Arc column voltage often passes
Adjust the gas flow rate and increase the internal shrinkage of the electrode to achieve this, but the arc column voltage cannot exceed 65% of the no-load voltage, otherwise it will cause the
The ion arc is unstable.

2. Cutting current
Increasing the cutting current can also increase the power of the plasma arc, but it is limited by the maximum allowable current, otherwise it will wait
The ion arc column becomes thicker, the slit width increases, and the electrode life decreases.
3. Gas flow
Increasing the gas flow can not only increase the arc column voltage, but also enhance the compression of the arc column and make the plasma arc energy more concentrated.
The medium and jetting force is stronger, so the cutting speed and quality can be improved. But if the gas flow is too large, it will shorten the arc column and lose
The increase in heat weakens the cutting ability until the cutting process cannot be carried out normally.
4. Electrode shrinkage
The so-called shrinkage refers to the distance between the electrode and the end surface of the cutting nozzle. A proper distance can make the arc get a good pressure in the cutting nozzle.
It can be reduced to obtain a plasma arc with concentrated energy and high temperature for effective cutting. The distance is too large or too small, it will make the electrode serious
Burnout, burnout of the cutting nozzle and reduced cutting ability. The shrinkage is generally 8~11mm.
5. Cutting nozzle height
The height of the cutting nozzle refers to the distance from the end of the cutting nozzle to the surface of the workpiece to be cut. The distance is generally 4-10mm. It retracts with the electrode
The amount is the same, the distance must be appropriate to give full play to the cutting efficiency of the plasma arc, otherwise it will reduce the cutting efficiency and cutting quality
Or burn the cutting nozzle.
6. Cutting speed
The above various factors directly affect the compression effect of the plasma arc, that is, the temperature and energy density of the plasma arc.
The high temperature and high energy of the plasma arc determine the cutting speed, so the above various factors are related to the cutting speed. In guarantee
On the premise of verifying the cutting quality, the cutting speed should be increased as much as possible. This not only improves productivity, but also reduces cut parts
The amount of deformation and the heat-affected zone in the kerf zone. If the cutting speed is not appropriate, the effect will be opposite, and the sticky residue will increase.
The cut quality is reduced.