| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems of storage and transfer of a bottle while easily using a mixed gas having different ratios of nitrogen and oxygen. SOLUTION: In a method and a unit for arc machining a workpiece, especially performing plasma cutting wherein current and a mixed gas containing oxygen and nitrogen are fed to a plasma torch and a plasma jet (10) obtained by ionizing the mixed gas by current is fed using the plasm torch, the concentration of oxygen and nitrogen in the mixed gas is 50% or less. The mixed gas is obtained by adding a prescribed quantity of nitrogen or oxygen depending on the situation just before the mixed gas is introduced into the torch. A quantity of nitrogen or oxygen is decided by the thickness of the workpiece, a desired working quantity and/or the intensity of current. |
