Abstract: A method of plasma multiarc welding by permanently burning direct-current arcs of different polarities makes use of a plasma forming gas and shielding mediums and the arcs are located so that the adjacent arcs have opposite polarities, consisting, according to the invention, in that all arcs are started between nonconsumable electrodes and a workpiece or some arcs are started between nonconsumable electrodes and a workpiece and other arcs are started between consumable electrodes and a workpiece, the currents of all arcs and the distance between the arcs being set so that the ratio of the product of the currents of two adjacent arcs to the distance therebetween is equal or more than 6.10.sup.3 A.sup.2 /cm.

Abstract: A method of DC reverse polarity plasma-arc machining of electrically conductive materials with the aid of a plasmatron the plasmatron having a nonconsumable electrode with an insert made from a high-melting point material, the method being in that the material being machined is heated by the heat of an electric arc burning between the positive nonconsumable electrode of the plasmatron and the material being machined, with the supply of the plasma-forming gas, the intensity of the working current of the arc being selected such that its ratio to the diameter of the nozzle channel is within 50 to 100 A/mm on condition that at least a portion of the near-the-electrode zone of the arc is maintained in electric contact with the high-melting point insert of the electrode.

Abstract: A plasma arc torch is of a two-part design and comprises two detachable and tightly joined parts mating with each other of which one part contains an electrode holder with an electrode, a nozzle disposed coaxially of said electrode and having means for supplying an electric current thereto. An insulator is located between said electrode holder and said nozzle, wherein there are also provided passages for the supply of plasma-generating gas and coolant, these being brought out onto the mating surface of the first part. The second part of the torch accommodates means for supplying an electric current to the electrode holder and means for supplying coolant and plasma-generating gas through passages brought out onto the mating surface of the second part so that they match with the corresponding passages of the first part on the surface of the joint thereof.

Abstract: An apparatus for plasma working of electrically-conductive materials wherein a gas-cooled non-consumable electrode, insulator and a gas-cooled nozzle of a plasmatron are interlinked with one another so as to form a chamber subdivided by a gas-permeable partition so that one of its parts communicates with the atmosphere through a central passage of the nozzle serving to discharge plasma-forming gas and the other part of the chamber communicates with a source of plasma-forming and cooling gas and also with the atmosphere through an additional passage, the non-consumable electrode passing through this partition and being disposed coaxially with the central passage of the nozzle.

Abstract: A method of producing electrode units for plasmatrons, according to which a direct-current arc is struck between a tungsten electrode and a melt, so that the electrode acts as a cathode, prior to dipping the electrode into the molten metal, intended e.g. for an electrode holder. Then the electrode is dipped into the melt, and the arc is extinguished.

Abstract: In a method for striking a main arc between the electrode and nozzle of a plasmatron there is initiated with the aid of high-frequency discharge an intermittently-arcing pilot arc whose flame bridges under the influence of a gas fed into the plasmatron the gap between the electrode of plasmatron and workpiece, completing thereby the circuit of main arc. The amplitude of pilot arc current is selected so as to be roughly equal to the steady current of the main arc whereas the frequency and on-off time ratio of the current are selected so as to assure that the flame of pilot arc is sustained unceasingly throughout the arcing of visually-monitored pilot arc.

Abstract: An electrode assembly for a plasmatron, comprising a holder being cooled having a high-heat insert mounted therein in contact with a near-the-electrode zone of an arc at one side thereof and in thermal and electrical contact with the cooled holder at the other side thereof; a chamber formed in said holder between said high-heat insert and cooled holder extending symmetrical to the insert axis and filled with a substance whose coefficient of thermal conductivity is lower than that of the material of the cooled holder, the substance filling the chamber being in constant contact with the high-heat insert.Used as a substance filling the chamber is a gaseous element, and as a high-heat insert is a metal selected from groups IV, V, or VI of the Periodic System, or an alloy based thereon.