Process and unit for. plasma-arc working with a gas mixture based on hydrogen, nitrogen and/or argon

摘要

Process and unit for the arc working, particularly plasma cutting, of a workpiece, in which a plasma torch is supplied with an electric current and with a gas mixture containing hydrogen and nitrogen and/or argon, and a plasma jet obtained by the ionization of the gas mixture by the electric current is delivered by means of the plasma torch. The hydrogen concentration in the gas mixture containing hydrogen and nitrogen and/or argon is less than 50%. The gas mixture is obtained by adding a defined amount of hydrogen to nitrogen and/or argon, immediately before the gas mixture is introduced into said torch. The defined amount of hydrogen is defined according to the thickness of the workpiece, to the grade of the constituent material of the workpiece, to the desired work rate and/or to the intensity of the electric current.