| Popis: |
The principle and equipment of water-air plasma cutting has been introduced in this paper. Especially, the function of water is not only to prevent the cutting pool from oxidizing in the form of a water curtain, but also to generate plasma in the center of arc. The Numerical Model of Low temperature Plasma has been eatablished with equation of energy, status, motion and chemical dynamic equation. Working process, mechanical properties and micro-structural features of 20 mm carbon steel processed by water-air plasma cutting and air plasma have been investigated, which choose the same parameters. The voice of plasma arc and dust of pool are being limited in the area of water curtain, so that the noise and dust of water air plasma cutting can be compared favorably with under-water plasma cutting. Lower temperature of water-air cutting plates is due to the fluent water taking off energy of metal pool during cutting. It is impossible to find oxide layer on the incisions surface of water-air plasma cutting, and the heat affected zone is so thin that welding can be carried out directly after cutting without any else process. So inclusion also can be avoided in the weld. But for air plasma cutting, lot of time is waste to remove oxide layer by mechanical polishing before welding. With the help of addition plasma arising from water, the water-air plasma arc becomes stronger, so smooth and high flatness cutting surface can be acquired. Compared with the technology of air plasma cutting, water-air plasma cutting has benefits of friendly working environment, higher quality incision and lower cost. |
