Other

Alexandr Yakovlevich Medvedev

David Grigorievich Bykhovsky

Jury Alexandrovich Bogorodsky

Yakov Vulfovich Rossomakho

Arkady Leonidovich Bolotnikov

Viktor N Kiselev

Vladimir Nikolaevich Firsov

Alexandr Yakovlevich Finkelshtein

Mikhail Isaakovich Zax

A non-consumable electrode for plasma-arc welding in an atmosphere of carbon dioxide or carbon-dioxide-based mixtures, includes a holder of copper or copper alloys and an active insert of hafnium embedded in the holder, with a hafnium oxycarbide layer disposed on the surface of the insert, the latter also including a graphite layer applied over the hafnium oxycarbide layer. A method of manufacturing the non-consumable electrode includes the steps of joining the holder of copper or copper alloys to the active insert of hafnium, connecting the holder to the negative pole of the power supply, placing the non-consumable electrode in an atmosphere of carbon dioxide, connecting an additional electrode to the positive pole of the power supply with an electric arc struck between the electrodes, forming a hafnium oxycarbide layer on the surface of the active insert at an electric arc current of up to 0.2 I, and subsequently forming a graphite layer over the previously formed hafnium oxycarbide layer as the current is increased from 0.2 I to I at a rate not exceeding 40 amperes per second, where I is the operating current of the non-consumable electrode.

Non-consumable electrode for plasma-arc welding

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.

Plasma arc torch

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.

Apparatus for plasma working of electrically-conductive materials and

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. The method for striking a main arc is embodied in an apparatus wherein the electrode and nozzle of the plasmatron are connected to opposing terminals of a source of power so that interconnected between the electrode and nozzle of plasmatron there is an oscillator and between the nozzle and source of power is a RC-circuit serving as a switching device in the electrode-to-nozzle circuit and, further, the nozzle and workpiece are interconnected by the RC-circuit and an inductance, L, connected in series.

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Saint-Petersburg, Russia

Alexandr Yakovlevich Medvedev