EP0111116A2 - Plasma torch having a conical electrode and a nozzle, the inner surface of which is at least in part conical - Google Patents

Plasma torch having a conical electrode and a nozzle, the inner surface of which is at least in part conical Download PDF

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Publication number
EP0111116A2
EP0111116A2 EP83110451A EP83110451A EP0111116A2 EP 0111116 A2 EP0111116 A2 EP 0111116A2 EP 83110451 A EP83110451 A EP 83110451A EP 83110451 A EP83110451 A EP 83110451A EP 0111116 A2 EP0111116 A2 EP 0111116A2
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EP
European Patent Office
Prior art keywords
electrode
nozzle
plasma torch
arc
torch according
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83110451A
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German (de)
French (fr)
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EP0111116A3 (en
EP0111116B1 (en
Inventor
Hans Josef Dr. Bebber
Heinrich-Otto Rossner
Gebhard Tomalla
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Vodafone GmbH
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Fried Krupp AG
Mannesmann AG
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Priority to AT83110451T priority Critical patent/ATE46419T1/en
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Publication of EP0111116A3 publication Critical patent/EP0111116A3/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/3436—Hollow cathodes with internal coolant flow
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/3478—Geometrical details

Definitions

  • the application relates to a method for introducing ionizable gas into a plasma of an arc burner, which is equipped with an optionally liquid-cooled electrode, which is located within a nozzle that conducts an ionizable gas into the arc, possibly also liquid-cooled, with a narrowed outlet, in which the electrode tip protrudes and a plasma torch to carry out the method.
  • Plasma torches of this type are known per se.
  • the durability of the electrodes and nozzles is particularly important in their operation.
  • the problems associated with this come to the fore wherever longer arc lengths of sometimes far more than 200 mm have to be used and where the atmosphere surrounding the torch contains gases that chemically, e.g. B. can attack by oxidation.
  • Such difficult conditions occur very often, for example, when operating metal melting furnaces with plasma torches.
  • the object is achieved by a method in which the ionizable gas is introduced into the plasma of the arc burner at an acute angle.
  • the acute angle is formed by the gas jet and the longitudinal axis of the plasma torch and is 6 to 40 °, preferably 12 °.
  • a plasma torch is used to carry out this method, which has an electrode which tapers conically towards the arc side and which is enclosed by the inner jacket of the nozzle.
  • the jacket of the electrode and the inner jacket of the nozzle with their conical boundary surfaces and their concentric arrangement, form an annular channel which directs the ionizable gas into the arc at an acute angle.
  • the conical outer surfaces of the electrode and nozzle lying opposite one another are arranged at least partially, preferably in the region of the electrode tip p, parallel to one another, or that the annular channel formed by them has a tapering profile towards the arc side.
  • the inner shell of the nozzle can change into a cylindrical shape.
  • the described shape of the nozzle and the electrode gives the gas flowing out through the ring channel a direction which ultimately brings about a decisive improvement in both the arc stability and the electrode protection against oxidation.
  • the cone angle of the electrode jacket is 12 to 60 °, that of the inner jacket of the nozzle 12 to 80 °.
  • a cone angle of 24 ° is preferably selected in each case.
  • the otherwise plane-shaped arc-side end of the electrode has a chamfer, or the electrode is concave or convex in the region of the electrode tip and provided with a chamfer.
  • the electrode can additionally have one or more channels for the flow of part of the ionizable gas.
  • a high-melting metal such as molybdenum, tantalum or tungsten is preferably used for the inner jacket of the nozzle.
  • the front part of the nozzle can consist of an insert which is connected to the plasma torch or the entire nozzle by screwing, welding, .soldering, press fitting or as a removable part by screwing.
  • the plasma torch shown in Fig. 1 consists essentially of an electrode 2 which is attached to a liquid-cooled electrode holder 1.
  • the electrode 2 has the shape of a truncated cone in the front region with a radius decreasing towards the end on the arc side.
  • the end of the electrode on the arc side which is essentially planar, has a circumferential chamfer 3.
  • the electrode can also have a concave or convex shape. Since it is known that tapered ends round off after prolonged use, corner and edge-shaped designs should be avoided.
  • the length of the electrode 2 is between 10 and 20 mm.
  • the cone angle ⁇ of the electrode 2 like the cone angle ⁇ which the inner jacket of the nozzle 9 forms, is 24 °.
  • the jacket 8 of the electrode 2 is enveloped by the inner jacket 4 of the nozzle 9, so that an annular channel 10 is formed therebetween, the boundary surfaces of which run parallel to one another in the region of the electrode tip or converge towards one another in the direction of the arc.
  • the ring channel 10 is dimensioned such that the radial exit velocity of the ionizable gas flowing through in the cold state is between 3 and 17 m / s.
  • the outlet 5 of the nozzle channel located in front of the electrode 2 is cylindrical in the exemplary embodiment, but can also be conical.
  • the electrode should protrude by about 1/4 to 1/3 of its smallest diameter behind the front end of the nozzle channel. This corresponds to e.g. B. at 20 mm diameter an amount of 5 to 6.5 mm. However, this amount should not be significantly greater than 6.5 mm, since then the cooling losses due to the part of the arc running in the channel become too high and, above all, there is the risk that the arc jumps to the nozzle and secondary arcs form.
  • the ratio of the free channel length to the electrode diameter can be reduced to values from 1/6 to 1/8 with approximately the same electrode protection, so that even with electrode diameters of more than 40 mm can achieve the desired advantages.
  • the nozzles are not made of copper, copper alloys or steel, as is generally the case, but instead have an insert made of a high-melting metal, preferably tungsten.
  • This insert which forms the inner jacket of the nozzle, can be connected to the plasma torch by pouring, welding, soldering, pressing in or as a removable part by screwing.
  • FIG. 2 An exemplary embodiment of a nozzle with a screwed insert 7 made of tungsten is shown in FIG. 2, for example.
  • This device has the particular advantage that a worn nozzle insert can be replaced within a short time and thus the replacement of the entire nozzle is not necessary.

Abstract

A plasma burner for introducing an ionizable gas stream into an electric arc comprises a nozzle having an outlet opening for discharging the gas stream. The outlet opening is defined by an outlet part of the nozzle; the outlet part has an inner nozzle face conically tapering, at an acute first cone angle, in a direction of the outlet opening. The plasma burner further has an electrode surrounded by the outlet part and having an outer electrode face conically tapering, at an acute second cone angle, in the direction of the outlet opening. The inner nozzle face and the outer electrode face together define a conical annular channel.

Description

Verfahren zur Einleitung von ionisierbarem Gas in ein Plasma eines Lichtbogenbrenners und Plasmabrenner zur Durchführung des VerfahrensProcess for introducing ionizable gas into a plasma of an arc torch and plasma torch for carrying out the process

Die Anmeldung betrifft ein Verfahren zur Einleitung von ionisierbarem Gas in ein Plasma eines Lichtbogenbrenners, der mit einer ggf. flüssigkeitsgekühlten Elektrode ausgestattet ist, die sich innerhalb einer ein ionisierbares Gas in den Lichtogen leitenden, ggf. ebenfalls flüssigkeitsgekühlten Düse mit verengtem Ausgang befindet, in welchen die Elektrodenspitze hineinragt und einen Plasmabrenner zur Durchführung des Verfahrens.The application relates to a method for introducing ionizable gas into a plasma of an arc burner, which is equipped with an optionally liquid-cooled electrode, which is located within a nozzle that conducts an ionizable gas into the arc, possibly also liquid-cooled, with a narrowed outlet, in which the electrode tip protrudes and a plasma torch to carry out the method.

Plasmabrenner dieses Typs sind an sich bekannt. Bei ihrem Betrieb ist die Haltbarkeit der Elektroden und Düsen besonders wichtig. Die damit verbundenen Probleme treten vor allem dort in den Vordergrund, wo mit größeren Lichtbogenlängen von teilweise weit mehr als 200 mm gearbeitet werden muß und wo die den Brenner umgebende Atmosphäre Gase enthält, die die Elektroden chemisch, z. B. durch Oxidation, angreifen können. Derartig erschwerende Verhältnisse treten beispielsweise beim Betrieb von Metallschmelzöfen mit Plasmabrennern sehr häufig auf. Hier besteht oft die Forderung, daß die Lichtbögen auch bei sehr großen Längen, z. B. bis 700 mm und mehr, sicher, d. h. ohne die Gefahr des Bogenabrisses, brennen.Plasma torches of this type are known per se. The durability of the electrodes and nozzles is particularly important in their operation. The problems associated with this come to the fore wherever longer arc lengths of sometimes far more than 200 mm have to be used and where the atmosphere surrounding the torch contains gases that chemically, e.g. B. can attack by oxidation. Such difficult conditions occur very often, for example, when operating metal melting furnaces with plasma torches. Here there is often the requirement that the arcs even at very long lengths, for. B. up to 700 mm and more, safely, d. H. burn without the risk of tearing the bow.

Hierzu, wie auch im Hinblick auf die Düsenhaltbarkeit, muß eine hohe Stabilität des Plasmalichtbogens sichergestellt werden. Je instabi'ler nämlich der Lichtbogen ausgebildet ist, je weniger straff und scharf begrenzt er ist, um so größer ist die Gefahr der Ausbildung von Nebenlichtbögen, die auf den Außenmantel der Düse springen und zum Schmelzgut oder zum Hauptlichtbogen brennen. Durch solche Nebenlichtbögen aber wird-die Düse meist augenblicklich zerstört.For this, as well as in terms of nozzle durability, a high stability of the plasma arc must be ensured be put. The more instable the arc is formed, the less tight and sharply defined it is, the greater the risk of secondary arcs forming which jump onto the outer jacket of the nozzle and burn to the melting material or to the main arc. Such secondary arcs, however, usually destroy the nozzle instantaneously.

Der hauptsächliche Verschleißmechanismus für gut gekühlte Elektroden, die aus hochschmelzenden Metallen wie Molybdän, Tantal oder Wolfram mit kleinen Beträgen von Emissionsmaterial, wie Thoriumoxid oder Zirkonoxid, hergestellt sind, besteht, soweit die Brenner nicht in einer den Elektroden gegenüber inerten Umgebung arbeiten, in der chemischen Zerstörung der Elektroden.The main wear mechanism for well-cooled electrodes made of refractory metals such as molybdenum, tantalum or tungsten with small amounts of emission material such as thorium oxide or zirconium oxide, as far as the burners do not work in an environment inert to the electrodes, is chemical Destruction of the electrodes.

Da beim Erschmelzen von Metallen meist oxidische Gase freigesetzt werden und sich im Ofenraum noch Restluft befindet, handelt es sich hierbei in der Regel um Oxidation. Diese wird allerdings durch das aus-der Düse ausströmende, die Elektrode umgebende inerte Plasmagas mehr oder weniger gemindert.Since oxidic gases are mostly released when metals are melted and there is still residual air in the furnace chamber, this is usually oxidation. However, this is more or less reduced by the inert plasma gas flowing out of the nozzle and surrounding the electrode.

In besonderem Maße nehmen die anderen Verschleißfaktoren, wie Schmelzen, Verdampfen, Sputtern, mit steigender Temperatur zu. Daher ist vor allem bei sehr hohen Stromstärken für eine intensive Elektrodenkühlung zu sorgen.The other wear factors, such as melting, evaporation, sputtering, increase in particular with increasing temperature. Therefore, intensive electrode cooling must be ensured, especially at very high currents.

Zum Zwecke der Elektrodenkühlung ist bereits in der DE-PS 14 40 628 vorgeschlagen worden, durch eine zentrale Bohrung in der Elektrodenspitze dem Lichtbogen ein Anteil des ionisierbaren Gases zuzuleiten. Die Elektrode ist im wesentlichen zylindrisch und an ihrem vorderen Ende mit einer Spitze versehen. Durch die zusätzliche Kühlung infolge des zentralen Gastromes wird zwar die Elektrodenerosion durch hohe Stromstärken erniedrigt. Jedoch ist bei einer solchen Anordnung die Elektrode gegen chemische Erosion unzureichend geschützt. Darüber hinaus kann diese Maßnahme auch die Erzeugung langer stabiler Lichtbögen nicht gewährleisten. Mit Wechselstrom können solche Brenner nur begrenzt eingesetzt werden.For the purpose of electrode cooling, it has already been proposed in DE-PS 14 40 628 to supply a portion of the ionizable gas to the arc through a central bore in the electrode tip. The electrode is essentially cylindrical and has a tip at its front end. Due to the additional cooling due to the central gastrom, electrode erosion is caused by high current intensities low. However, with such an arrangement, the electrode is insufficiently protected against chemical erosion. In addition, this measure cannot guarantee the generation of long, stable arcs. Such burners can only be used to a limited extent with alternating current.

Es ist daher Aufgabe der Erfindung, einen Plasmabrenner zu schaffen, der die vorerwähnten Nachteile nicht besitzt und auch unter den erschwerten Bedingungen beim Betrieb in Schrottschmelzöfen mit Lichtbogenlängen über 200 mm und vornehmlich auch beim Betrieb mit Wechsel- bzw. Drehstrom hohe Düsen- und Elektrodenstandzeiten aufweist.It is therefore an object of the invention to provide a plasma torch which does not have the aforementioned disadvantages and which also has long nozzle and electrode service lives, even under the difficult conditions when operating in scrap melting furnaces with arc lengths over 200 mm and primarily also when operating with alternating or three-phase current .

Die Aufgabe wird durch ein Verfahren gelöst, bei dem das ionisierbare Gas unter einem spitzen Winkel in das Plasma des Lichtbogenbrenners eingeleitet wird. Der spitze Winkel wird von dem Gasstrahl und der Plasmabrennerlängsachse gebildet und beträgt 6 bis 40°, vorzugsweise'12°.The object is achieved by a method in which the ionizable gas is introduced into the plasma of the arc burner at an acute angle. The acute angle is formed by the gas jet and the longitudinal axis of the plasma torch and is 6 to 40 °, preferably 12 °.

Nach einer Weiterbildung der Erfindung wird zur Durchführung dieses Verfahrens ein Plasmabrenner verwendet, der eine sich zur Lichtbogenseite hin konisch verjüngende Elektrode aufweist, die von dem Innenmantel der Düse umschlossen wird. Der Mantel der Elektrode und der Innenmantel der Düse bilden mit ihren kegelförmigen Begrenzungsflächen und ihrer konzentrischen Anordnung einen Ringkanal, der das ionisierbare Gas unter spitzem Winkel in den Lichtbogen leitet. Hierzu ist es erforderlich, daß die sich gegenüberliegenden kegelförmigen Mantelflächen von Elektrode und Düse zumindest teilweise, bevorzugt im Bereich der Elektrodenspitzepparallel zueinander angeordnet sind bzw. der durch sie gebildete Ringkanal einen sich zur Lichtbogenseite hin verjüngenden Verlauf hat. In dem die Elektrodenvorderseite zur Lichtbogenseite hin überragenden Teil der Düse kann der Innenmantel der Düse in eine Zylinderform übergehen. Durch die geschilderte Gestalt der Düse und der Elektrode erhält das durch den.Ringkanal ausströmende Gas eine Richtung, die letztlich eine entscheidende Verbesserung sowohl der Bogenstabilität als auch des Elektrodenschutzes vor Oxidation bewirkt.According to a development of the invention, a plasma torch is used to carry out this method, which has an electrode which tapers conically towards the arc side and which is enclosed by the inner jacket of the nozzle. The jacket of the electrode and the inner jacket of the nozzle, with their conical boundary surfaces and their concentric arrangement, form an annular channel which directs the ionizable gas into the arc at an acute angle. For this purpose, it is necessary that the conical outer surfaces of the electrode and nozzle lying opposite one another are arranged at least partially, preferably in the region of the electrode tip p, parallel to one another, or that the annular channel formed by them has a tapering profile towards the arc side. In which the electrode front to the arc side The protruding part of the nozzle, the inner shell of the nozzle can change into a cylindrical shape. The described shape of the nozzle and the electrode gives the gas flowing out through the ring channel a direction which ultimately brings about a decisive improvement in both the arc stability and the electrode protection against oxidation.

Der Kegelwinkel des Elektrodenmantels beträgt nach einer weiteren Ausgestaltung der Erfindung 12 bis 60°, der des Innenmantels der Düse 12 bis 80°. Vorzugsweise werden jedoch jeweils Kegelwinkel von 24° gewählt.According to a further embodiment of the invention, the cone angle of the electrode jacket is 12 to 60 °, that of the inner jacket of the nozzle 12 to 80 °. However, a cone angle of 24 ° is preferably selected in each case.

Vorteilhafterweise weist das ansonsten plangestaltete lichtbogenseitige Ende der Elektrode eine Fase auf oder die Elektrode ist im Bereich der Elektrodenspitze konkav oder konvex geformt und mit einer Fase versehen. Je nach Größe des Plasmabrenners bzw. der Lichtbogenstärke kann die Elektrode zusätzlich ein oder mehrere Kanäle zum Durchströmen mit einem Teil des ionisierbaren Gases aufweisen.Advantageously, the otherwise plane-shaped arc-side end of the electrode has a chamfer, or the electrode is concave or convex in the region of the electrode tip and provided with a chamfer. Depending on the size of the plasma torch or the strength of the arc, the electrode can additionally have one or more channels for the flow of part of the ionizable gas.

Für den Innenmantel der Düse wird bevorzugt ein hochschmelzendes Metall wie beispielsweise Molybdän, Tantal oder Wolfram verwendet. Der Düsenvorderteil kann aus einem Einsatz bestehen, der durch Eingießen, Schweißen, .Löten, Preßpassung oder als herausnehmbares Teil durch Verschraubung mit dem Plasmabrenner bzw. der gesamten Düse verbunden ist.A high-melting metal such as molybdenum, tantalum or tungsten is preferably used for the inner jacket of the nozzle. The front part of the nozzle can consist of an insert which is connected to the plasma torch or the entire nozzle by screwing, welding, .soldering, press fitting or as a removable part by screwing.

Ein Ausführungsbeispiel der Erfindung ist in den Zeichnungen dargestellt.An embodiment of the invention is shown in the drawings.

Es zeigen

  • Fig. 1, 2 jeweils eine Querschnittsansicht einer Düse mit mittig angeordneter Elektrode.
Show it
  • 1, 2 each show a cross-sectional view of a nozzle with a centrally arranged electrode.

Der in Fig. 1 dargestellte Plasmabrenner besteht im wesentlichen aus einer Elektrode 2, die an einem flüssigkeitsgekühlten Elektrodenhalter 1 befestigt ist. Die Elektrode 2 hat im vorderen Bereich die Form eines Kegelstumpfes mit zum lichtbogenseitigen Ende abnehmendem Radius. Das lichtbogenseitige Ende der Elektrode, das.im wesentlichen eben gestaltet ist, weist eine umlaufende Fase 3 auf. In diesem Bereich kann die Elektrode auch konkav oder konvex geformt sein. Da bekannt ist, daß sich spitz zulaufende Enden nach längerem Gebrauch abrunden, sollte allerdings auf ecken- und kantenförmige Ausbildungen verzichtet werden. Die Länge der Elektrode 2 beträgt zwischen 10 und 20 mm. Kürzere Elektroden haben den Nachteil, daß sie trotz eines etwas langsameren Rückbrandes früher ausgetauscht werden müssen, zu lange Elektroden dagegen werden an der Lichtbogenseite zu heiß und verschleißen daher schneller. Der Kegelwinkel α der Elektrode 2 beträgt, ebenso wie der Kegelwinkel β, den der Innenmantel der Düse 9 bildet, 24°. Der Mantel 8 der Elektrode 2 wird von dem Innenmantel 4 der Düse 9 umhüllt, so daß sich dazwischen ein-Ringkanal 10 bildet, dessen Begrenzungsflächen im Bereich der Elektrodenspitze parallel zueinander verlaufen oder in Richtung auf den Lichtbogen aufeinander zulaufen. Der Ringkanal 10 ist so bemessen, daß die radiale Austrittsgeschwindigkeit des durchströmenden ionisierbaren Gases im kalten Zustand zwischen 3 und 17 m/s beträgt. Der vor der Elektrode 2 befindliche Auslauf 5 des Düsenkanals ist im Ausführungsbeispiel zylindrisch, kann aber auch konisch ausgebildet sein.The plasma torch shown in Fig. 1 consists essentially of an electrode 2 which is attached to a liquid-cooled electrode holder 1. The electrode 2 has the shape of a truncated cone in the front region with a radius decreasing towards the end on the arc side. The end of the electrode on the arc side, which is essentially planar, has a circumferential chamfer 3. In this area, the electrode can also have a concave or convex shape. Since it is known that tapered ends round off after prolonged use, corner and edge-shaped designs should be avoided. The length of the electrode 2 is between 10 and 20 mm. Shorter electrodes have the disadvantage that they have to be replaced earlier despite a somewhat slower burn-back, while electrodes that are too long become too hot on the arc side and therefore wear out faster. The cone angle α of the electrode 2, like the cone angle β which the inner jacket of the nozzle 9 forms, is 24 °. The jacket 8 of the electrode 2 is enveloped by the inner jacket 4 of the nozzle 9, so that an annular channel 10 is formed therebetween, the boundary surfaces of which run parallel to one another in the region of the electrode tip or converge towards one another in the direction of the arc. The ring channel 10 is dimensioned such that the radial exit velocity of the ionizable gas flowing through in the cold state is between 3 and 17 m / s. The outlet 5 of the nozzle channel located in front of the electrode 2 is cylindrical in the exemplary embodiment, but can also be conical.

Durch diese erfindungsgemäße Ausführung von Düse 9 und Elektrode 2 erhält das durch den Ringspalt ausströmende Gas eine Richtung, die, wie zahlreiche Versuche zeigten, eine entscheidende Verbesserung sowohl der Bogenstabilität als auch des Elektrodenschutzes vor Oxidation bewirkt. So wurden beim Betrieb mit Wechselstrom bis zu 700 mm lange, stabil brennende Lichtbögen erzeugt. Hierbei zeigten Elektroden mit einem stirnseitigen Durchmesser bis zu 19 mm auch nach einigen Stunden Betriebszeit keinerlei Oxidationsspuren.This inventive design of nozzle 9 and electrode 2 gives the gas flowing out through the annular gap a direction which, as numerous tests have shown, improves decisively both the arc stability and the electrode protection against oxidation causes. In this way, when the system was operated with alternating current, up to 700 mm long, stable burning arcs were generated. Here, electrodes shown with an end-side diameter up to 19 mm even after several hours of operating time acids p Oxidationss no.

Bei Verwendung von Elektroden größeren Durchmessers bzw. Querschnittes, z. B. zum Zwecke einer Erhöhung der Stromstärke, kann es zweckmäßig sein, einen Anteil des ionisierbaren Gases durch eine oder mehrere Bohrungen 6 in der Elektrode zuzuführen. Es hat sich zwar herausgestellt, daß die alleinige Zuführung eines Anteils an ionisierbarem Gas durch Bohrungen in der Elektrode nicht ausreicht, um die erfindungsgemäße Aufgabe zu lösen, jedoch bewirkt die erfindungsgemäße Gaszuführung kombiniert mit der zusätzlichen Zuführung durch eine oder mehrere Bohrungen in der Elektrode einen vorteilhaften Schutz für die Elektrode.When using electrodes of larger diameter or cross-section, e.g. B. for the purpose of increasing the current, it may be appropriate to supply a portion of the ionizable gas through one or more holes 6 in the electrode. It has been found that the sole supply of a portion of ionizable gas through holes in the electrode is not sufficient to achieve the object according to the invention, but the gas supply according to the invention combined with the additional supply through one or more holes in the electrode has an advantageous effect Protection for the electrode.

Bei der erfindungsgemäßen Ausführung ohne zentrale Gaszufuhr soll die Elektrode um etwa 1/4 bis 1/3 ihres kleinsten Durchmessers hinter dem vorderen Ende des Düsenkanals zurückstehen. Dies entspricht z. B. bei 20 mm Durchmesser einem Betrag von 5 bis 6,5 mm. Wesentlich größer als 6,5 mm sollte dieser Betrag allerdings nicht sein, da dann die Kühlverluste durch den im Kanal verlaufenden Teil des Lichtbogens zu hoch werden und vor allem auch die Gefahr besteht, daß der Bogen zur Düse springt und sich Nebenbögen bilden. Durch die genannte Kombination der Gaszufuhr durch den Ringkanal und durch Bohrungen in der Elektrode kann aber das Verhältnis der freien Kanallänge zum Elektrodendurchmesser.auf Werte von 1/6 bis 1/8 bei etwa gleich gutem Elektrodenschutz vermindert werden, so daß sich auch bei Elektrodendurchmessern von mehr als 40 mm die angestrebten Vorteile erzielen lassen.In the embodiment according to the invention without a central gas supply, the electrode should protrude by about 1/4 to 1/3 of its smallest diameter behind the front end of the nozzle channel. This corresponds to e.g. B. at 20 mm diameter an amount of 5 to 6.5 mm. However, this amount should not be significantly greater than 6.5 mm, since then the cooling losses due to the part of the arc running in the channel become too high and, above all, there is the risk that the arc jumps to the nozzle and secondary arcs form. Through the combination of the gas supply through the ring channel and through bores in the electrode, the ratio of the free channel length to the electrode diameter can be reduced to values from 1/6 to 1/8 with approximately the same electrode protection, so that even with electrode diameters of more than 40 mm can achieve the desired advantages.

Um auch bei längerer Betriebszeit die Form des Ringkanals weitgehend bestehen zu lassen, werden die Düsen, nicht wie allgemein üblich,aus Kupfer, Kupferlegierungen oder Stahl hergestellt, sondern erhalten einen Einsatz aus einem hochschmelzenden Metall, vorzugsweise Wolfram. Dieser den Innenmantel der Düse bildende Einsatz kann durch Eingießen, Schweißen, Löten, Einpressen oder als herausnehmbares Teil durch Verschraubung mit dem Plasmabrenner verbunden werden.In order to largely maintain the shape of the ring channel even during a long period of operation, the nozzles are not made of copper, copper alloys or steel, as is generally the case, but instead have an insert made of a high-melting metal, preferably tungsten. This insert, which forms the inner jacket of the nozzle, can be connected to the plasma torch by pouring, welding, soldering, pressing in or as a removable part by screwing.

Ein Ausführungsbeispiel einer Düse mit geschraubtem Einsatz 7 aus Wolfram ist beispielsweise in Fig. 2 dargestellt. Diese Vorrichtung hat insbesondere den Vorteil, daß ein verschlissener Düseneinsatz innerhalb kurzer Zeit gewechselt werden kann und somit der Ersatz der gesamten Düse nicht erforderlich wird.An exemplary embodiment of a nozzle with a screwed insert 7 made of tungsten is shown in FIG. 2, for example. This device has the particular advantage that a worn nozzle insert can be replaced within a short time and thus the replacement of the entire nozzle is not necessary.

Claims (11)

1. Verfahren zur Einleitung von ionisierbarem Gas in ein Plasma eines Lichtbogenbrenners, der mit einer ggf. flüssigkeitsgekühlten Elektrode ausgestattet ist, die sich innerhalb einer das ionisierbare Gas in den Lichtbogen leitenden ggf. ebenfalls flüssigkeitsgekühlten Düse mit verengtem Ausgang befindet, in welchen die Elektrodenspitze hineinragt, dadurch gekennzeichnet, daß das ionisierbare Gas unter einem spitzen Winkel in das Plasma des Lichtbogenbrenners eingeleitet wird.1. Method for introducing ionizable gas into a plasma of an arc burner, which is equipped with a possibly liquid-cooled electrode, which is located within a possibly liquid-cooled nozzle with a narrowed outlet that conducts the ionizable gas into which the electrode tip protrudes , characterized in that the ionizable gas is introduced into the plasma of the arc burner at an acute angle. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der zwischen dem Gasstrahl und der Plasmabrennerlängsachse gebildete spitze Winkel zwischen 6° und 400, vorzugsweise bei 12° liegt.2. The method according to claim 1, characterized in that the acute angle formed between the gas jet and the plasma torch longitudinal axis is between 6 ° and 40 0 , preferably at 12 °. 3. Plasmabrenner zur Durchführung des Verfahrens nach Ansprüchen 1 und 2, dadurch gekennzeichnet, daß der Mantel (8) der sich zur Lichtbogenseite hin konisch verjüngenden Elektrode (2) und der diesen umschließende Innenmantel (4) der Düse (9) als konzentrisch angeordnete, zumindest teilweise kegelförmige Begrenzungsflächen einen Ringkanal (10) bilden, durch den das Inertgas unter spitzem Winkel in den Lichtbogen geleitet wird.3. Plasma torch for performing the method according to claims 1 and 2, characterized in that the jacket (8) of the conically tapering towards the arc side electrode (2) and the inner jacket surrounding this (4) of the nozzle (9) as a concentrically arranged, at least partially conical boundary surfaces form an annular channel (10) through which the inert gas is conducted into the arc at an acute angle. 4. Plasmabrenner nach Anspruch 3, dadurch gekennzeichnet, daß sich der Ringkanal (10) zur Lichtbogenseite hin verjüngt.4. Plasma torch according to claim 3, characterized in that the annular channel (10) tapers towards the arc side. 5. Plasmabrenner nach Ansprüchen 3 und 4, dadurch gekennzeichnet, daß der Kegelwinkel (α) der konisch ausgebildeten Elektrode (2) zwischen 12 und 600, vorzugsweise bei 24° liegt.5. Plasma torch according to claims 3 and 4, characterized in that the cone angle (α) of the conical electrode (2) is between 12 and 60 0 , preferably at 24 °. 6. Plasmabrenner nach Ansprüchen 3 und 4, dadurch gekennzeichnet, daß der durch den Innenmantel (4) der Düse (9) gebildete Kegelwinkel (β) zwischen 12 und 800, vorzugsweise bei 24° liegt.6. Plasma torch according to claims 3 and 4, characterized in that the cone angle (β) formed by the inner jacket (4) of the nozzle (9) is between 12 and 80 0 , preferably at 24 °. 7. Plasmabrenner nach Ansprüchen 3 bis 5, dadurch gekennzeichnet, daß das ansonsten plangestaltete lichtbogenseitige Ende der Elektrode (2) eine Fase (3) aufweist.7. Plasma torch according to claims 3 to 5, characterized in that the otherwise plan-shaped arc-side end of the electrode (2) has a chamfer (3). 8. Plasmabrenner nach Ansprüchen 3 bis 5, dadurch gekennzeichnet, daß das lichtbogenseitige Ende der Elektrode (2) konkave oder konvexe Konturen aufweist und mit einer Fase (3) versehen ist.8. Plasma torch according to claims 3 to 5, characterized in that the arc-side end of the electrode (2) has concave or convex contours and is provided with a chamfer (3). 9. Plasmabrenner nach Ansprüchen 3, 4, 5 und 8, dadurch gekennzeichnet, daß der Innenmantel der Düse (9) aus einem hochschmelzenden Metall besteht.9. Plasma torch according to claims 3, 4, 5 and 8, characterized in that the inner jacket of the nozzle (9) consists of a high-melting metal. 10. Plasmabrenner nach Anspruch 9, dadurch gekenn- .zeichnet, daß der Düsenvorderteil einen Einsatz (7) enthält, der durch Eingießen, Schweißen, Löten, Preßpassung oder als herausnehmbares Teil durch Verschraubung mit der Düse (9) verbunden ist.10. A plasma torch according to claim 9, characterized in that the nozzle front part contains an insert (7) which is connected by pouring, welding, soldering, press fitting or as a removable part by screwing with the nozzle (9). 11. Plasmabrenner nach einem der Ansprüche 3 bis 10, dadurch gekennzeichnet, daß die Elektrode zusätzlich einen oder mehrere Kanäle (6) zum Durchströmen mit einem Teil des ionisierbaren Gases aufweist.11. Plasma torch according to one of claims 3 to 10, characterized in that the electrode additionally has one or more channels (6) for flow with part of the ionizable gas.
EP83110451A 1982-11-10 1983-10-20 Plasma torch having a conical electrode and a nozzle, the inner surface of which is at least in part conical Expired EP0111116B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83110451T ATE46419T1 (en) 1982-11-10 1983-10-20 PLASMA TORCH WITH A CONICAL ELECTRODE AND A NOZZLE WITH AT LEAST PARTIALLY CONICAL INNER JACKET.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3241476 1982-11-10
DE19823241476 DE3241476A1 (en) 1982-11-10 1982-11-10 METHOD FOR INTRODUCING IONIZABLE GAS INTO A PLASMA OF AN ARC BURNER, AND PLASMA TORCHER FOR CARRYING OUT THE METHOD

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EP0111116A2 true EP0111116A2 (en) 1984-06-20
EP0111116A3 EP0111116A3 (en) 1985-10-09
EP0111116B1 EP0111116B1 (en) 1989-09-13

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US (1) US4594496A (en)
EP (1) EP0111116B1 (en)
JP (1) JPS5999700A (en)
AT (1) ATE46419T1 (en)
DE (1) DE3241476A1 (en)
FI (1) FI84548C (en)
ZA (1) ZA838333B (en)

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EP0178288A2 (en) * 1984-10-11 1986-04-16 VOEST-ALPINE INDUSTRIEANLAGENBAU GESELLSCHAFT m.b.H. Plasma burner
FR2726964A1 (en) * 1994-11-11 1996-05-15 Sulzer Metco Ag NOZZLE FOR BURNER HEAD OF A PLASMA SPRAYING APPARATUS
GB2363957A (en) * 2000-06-21 2002-01-09 Inocon Technologie Gmbh Plasma torch nozzle/electrode arrangement

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FR2726964A1 (en) * 1994-11-11 1996-05-15 Sulzer Metco Ag NOZZLE FOR BURNER HEAD OF A PLASMA SPRAYING APPARATUS
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Also Published As

Publication number Publication date
FI834038A0 (en) 1983-11-03
DE3241476A1 (en) 1984-05-10
US4594496A (en) 1986-06-10
EP0111116A3 (en) 1985-10-09
FI84548C (en) 1991-12-10
DE3241476C2 (en) 1990-02-22
JPS5999700A (en) 1984-06-08
FI84548B (en) 1991-08-30
EP0111116B1 (en) 1989-09-13
ATE46419T1 (en) 1989-09-15
ZA838333B (en) 1984-07-25

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