Igniting method for plasma torch

Abstract

Abstract PURPOSE:To eliminate the influence to an object to be heated by a pilot arc by extinguishing the pilot arc when a main arc is ignited and impressing the pilot arc power source voltage on between an electrode and a nozzle just before the arc is extinguished to ignite the pilot arc and not necessitating the frequent high-frequency discharge. CONSTITUTION:In a state with the main arc M ignited between the electrode 2 and the object M to be heated, an ionized atmosphere layer 8 having conductivity where plasma gas G is made in an ionized state is formed around the arc M extending to the object W to be heated from the ignition 2 via the lower end of a nozzle 3. Then, only the DC voltage by a pilot arc power source 5 is impressed on between the electrode 2 and the nozzle 3 before the arc M is extinguished. In this way, the pilot arc P can be ignited without destroying the insulation between the electrode 2 and the nozzle 3 by high-frequency output of a high-frequency power source 6. Furthermore, it is prevented that the quantity of heat radiation of the arc P exerts the thermal influence upon the object W to be heated by extinguishing the arc P after the arc M is ignited.

Inventors

• 👤 Yasunobu Shimomoto
• 👤 下元　康延

Bibliographic Details