Abstract: The method consists in that a flat work in an initial position is oriented horizontally between cooled mold beams. Plasma torches are arranged in line across the parallel side edges so that the anode spots of the extreme torches are confined by said edges of the work. By supplying a plasma forming gas and electric current to the plasma torches the work is heated with the formation of a metal pool which extends across the work from edge to edge. By relatively moving the work and the plasma torches in a horizontal plane and along the edges of the work movement of the metal pool over the surface thereof is effected and thereby a remelted layer as thick as the pool is deep, is obtained. The apparatus for carrying out the method comprises a sealed chamber containing a mold having two beams arranged in a horizontal plane and being parallel to one another.

Abstract: The proposed method relates to the ionization of plasma-generating gas in a ilot arc before being supplied to the electrode region, thus generating charges in this electrode region, the charges promoting dispersion of an arc spot. For this purpose, an electrode assembly is provided within the plasma-arc torch, which electrode assembly comprises a hollow tungsten electrode and a solid electrode of the same metal, the solid electrode being radially spaced from the hollow electrode. Both electrodes are put in an electric power circuit, whereby an arc is initiated between the electrodes when switching on the electric circuit, plasma being generated in the arc, which plasma serves to start the main arc and provides for dispersion of the arc spot over the surface of the hollow electrode. This decreases the current density in the arc spots and, hence, minimizes electrode erosion.

Abstract: A plasma-arc furnace comprises a casing with plasma torches, particularly ree torches, mounted therewithin in symmetrical relationship relative to the vertical axis thereof. Each of these torches comprises a body provided with a nozzle and an axial conduit for feeding a plasma-forming gas therethrough, and a cylindrical electrode disposed within said conduit. According to the invention, the distance between the centers of working ends of electrodes disposed within adjacent plasma torches is not more than 15 diameters of the electrode.

Abstract: In a plasma-arc torch for melting metals the electrode assembly comprises an electrode holder made of copper alloys and having a butt portion which rigidly secures a tungsten electrode by means of diffusion welding. The invention provides for a welded joint between the electrode and the electrode holder, a nonconsumable current-conducting interlayer made of titanium, copper and tungsten being placed therebetween.