JPS6483376A - Method for operating plasma torch - Google Patents

Abstract

PURPOSE:To prevent electrodes from burning and consumption by providing a changeover switch to a power source and applying inert gas and the nontransferred mode at the time of starting operation and at the time of stopping it for a time and changing over these to active gas and the transferred mode at the time of cutting work. CONSTITUTION:An intermediate electrode 3 is provided with respect to a bar- shaped electrode 2 of a plasma torch 1 to demarcate a first gas channel 10. Further, a cylindrical outer electrode 4 to form a second gas channel is arranged to the outside of the electrode 3. At the time of starting the plasma torch 1, the voltage is impressed between the electrodes 2 and 4 via the changeover switch 101 and a pilot arc and a main arc are ignited in order by the inert gas and the nontransferred more. At the time of the cutting work, plasma working is performed by the active gas and transferred mode. At the time of starting and at the time of stopping for a time, since both the negative electrode 2 and the positive electrode 4 are in the inert gas, the electrodes 2 and 4 are prevented from burning and being consumed.