| 摘要 |
Plasma arc or laser cutting uses a mix of reactive and reducing gas flows to cut sheets of stainless steel, aluminum and other non-ferrous metals. The reducing gas flow to the cut varies as a percentage of the total gas flow to maintain a reducing atmosphere down through the cut, but to leave a predominantly oxidizing atmosphere at the intersection of the cut and the bottom surface of the sheet being cut. In plasma arc cutting these flows can also be characterized as either a plasma gas flow, one that forms the arc, or a shield gas flow that surrounds the arc. The reactive gas is preferably a flow of air, oxygen, nitrogen, carbon dioxide or a combination of these gases. The reducing gas is preferably hydrogen, hydrogen 35, methane, or a mixture of these gases. For aluminum, the reactive gas is preferably air or nitrogen and the reducing gas is preferably methane or a mixture of methane and air. In laser cutting the reducing gases such as methane can be used by mixing them with reactive assist gases. |
