A numerically controlled plasma cutting machine with a high no-load voltage and operating voltage requires a higher voltage for stabilizing the plasma arc when using a gas having a high ionization energy such as nitrogen, hydrogen or air. When the current is constant, an increase in voltage means an increase in the arc enthalpy and an increase in the cutting ability. If the diameter of the jet is reduced and the flow rate of the gas is increased while the enthalpy is increased, a faster cutting speed and a better cutting quality are often obtained.
1. Hydrogen is usually used as an auxiliary gas to mix with other gases. For example, the famous gas H35 (hydrogen volume fraction of 35%, the rest is argon) is one of the most powerful gas arc cutting ability, which is mainly beneficial to hydrogen. Since hydrogen can significantly increase the arc voltage, the hydrogen plasma jet has a high enthalpy value, and when used in combination with argon gas, the cutting ability of the plasma jet is greatly improved.
2. Oxygen can increase the speed of cutting low carbon steel materials. When cutting with oxygen, the cutting mode and the CNC flame cutting machine are very imaginable. The high temperature and high energy plasma arc makes the cutting speed faster. The spiral duct machine must be combined with the electrode resistant to high temperature oxidation, and the electrode is prevented when starting the arc. Impact protection to extend the life of the electrode.
3, the air contains about 78% of the volume of nitrogen, so the use of air cutting to form the slag and the nitrogen is very imaginary; air also contains about 21% of the volume of oxygen, because of the presence of oxygen, air The speed of cutting low carbon steel materials is also high; at the same time, air is also the most economical working gas. However, when air cutting is used alone, there are problems such as dross and oxidation of the slit, nitrogen increase, etc., and the lower life of the electrode and the nozzle also affects work efficiency and cutting cost. Since plasma arc cutting generally uses a power source with constant current or steep drop characteristics, the current change is small after the nozzle height is increased, but the arc length is increased and the arc voltage is increased, thereby increasing the arc power; The arc length exposed to the environment increases, and the energy lost by the arc column increases.
4. Nitrogen is a commonly used working gas. Under the condition of higher power supply voltage, the nitrogen plasma arc has better stability and higher jet energy than argon, even if it is a material with a high viscosity for cutting liquid metal. In stainless steel and nickel-based alloys, the amount of slag on the lower edge of the slit is also small. Nitrogen can be used alone or in combination with other gases. Plasma cutting machines are often used. For example, nitrogen or air is often used as a working gas for automated cutting. These two gases have become standard gases for high-speed cutting of carbon steel. Nitrogen is sometimes used as an arcing gas for oxygen plasma arc cutting.
5. Argon gas hardly reacts with any metal at high temperature, and the argon numerical control plasma cutting machine is very stable. Moreover, the nozzles and electrodes used have a high service life. However, the argon plasma arc has a low voltage, a low enthalpy value, and a limited cutting capacity. The thickness of the cut is about 25% lower than that of air cutting. In addition, the surface tension of the molten metal is larger in an argon-protected environment. It is about 30% higher than in a nitrogen atmosphere, so there will be more problems with drossing. Even if a mixture of argon and other gases is used, there is a tendency to stick to the slag. Therefore, pure argon gas has rarely been used alone for plasma cutting.
The use and selection of gas in CNC plasma cutting machine is very important. The use of gas will seriously affect the cutting precision and slag.
Post time: Sep-02-2019
