Introduction
Plasma arc welding refers to a fusion welding method that uses a high-energy-density plasma arc beam as a welding heat source. Plasma arc welding has the characteristics of concentrated energy, high productivity, fast welding speed, low stress and deformation, stable arc, and is suitable for welding thin plates and box materials. It is particularly suitable for welding various refractory, easily oxidized, and heat-sensitive metal materials (such as tungsten, molybdenum, copper, nickel, titanium, etc.).
The gas is heated by the arc and dissociated. When it passes through the water-cooled nozzle at high speed, it is compressed, increasing the energy density and dissociation degree to form a plasma arc. Its stability, heat generation, and temperature are higher than those of ordinary arcs, so it has greater penetration and welding speed. The gas that forms the plasma arc and the protective gas around it generally use pure argon. According to the material properties of various workpieces, helium, nitrogen, argon, or a mixture of the two are also used.
Principle
Plasma arc cutting is a commonly used cutting process for metal and non-metal materials. It uses high-speed, high-temperature and high-energy plasma airflow to heat and melt the material to be cut, and uses internal or external high-speed airflow or water flow to push the molten material away until the plasma airflow beam penetrates the back to form a cut.
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Features
1. Micro-beam plasma arc welding can weld foil and thin plates.
2. It has a pinhole effect and can achieve single-sided welding and double-sided free forming.
3. The plasma arc has a high energy density, high arc column temperature, and strong penetration ability. It can achieve 10-12mm thick steel without beveling. It can weld through both sides at one time, with fast welding speed, high productivity, and small stress deformation.
4. The equipment is relatively complex, with high gas consumption, strict requirements on the gap between the assembly and the cleanliness of the workpiece, and is only suitable for indoor welding.
Power Supply
When plasma arc welding is used, direct current and droop characteristic power supplies are usually used. Due to the unique operating characteristics obtained from the special torch arrangement and the separate plasma and shielding gas flows, a normal TIG power supply can be added to the plasma console, and a specially constructed plasma system can also be used. It is not easy to stabilize the plasma arc when using sine wave AC. When the distance between the electrode and the workpiece is long and the plasma is compressed, the plasma arc is difficult to function, and in the positive half cycle, the overheated electrode will make the conductive tip spherical, which will interfere with the stability of the arc.
A dedicated DC switching power supply can be used. By adjusting the balance of the waveform to reduce the duration of the electrode positive pole, the electrode is fully cooled to maintain the pointed conductive tip shape and form a stable arc.
Post time: Sep-12-2024
