EP0427591B1 - Plasma torch with non-cooled plasma gas injection - Google Patents

Plasma torch with non-cooled plasma gas injection Download PDF

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Publication number
EP0427591B1
EP0427591B1 EP90403045A EP90403045A EP0427591B1 EP 0427591 B1 EP0427591 B1 EP 0427591B1 EP 90403045 A EP90403045 A EP 90403045A EP 90403045 A EP90403045 A EP 90403045A EP 0427591 B1 EP0427591 B1 EP 0427591B1
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EP
European Patent Office
Prior art keywords
plasma
electrodes
plasma torch
injection
torch
Prior art date
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Expired - Lifetime
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EP90403045A
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German (de)
French (fr)
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EP0427591A1 (en
Inventor
Maxime Labrot
Didier Pineau
Jean Feuillerat
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Airbus Group SAS
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Airbus Group SAS
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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
    • 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
    • H05H1/341—Arrangements for providing coaxial protecting fluids
    • 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
    • H05H1/3421—Transferred arc or pilot arc mode
    • 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
    • H05H1/3431—Coaxial cylindrical electrodes
    • 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
    • H05H1/28—Cooling arrangements

Definitions

  • the present invention relates to electric arc plasma torches, implementing the injection of a plasma gas into an internal chamber, which is formed in the torch and which is crossed by an electric arc generated between two electrodes.
  • the temperatures reached by the plasma leaving the torch can exceed 10,000 ° C.
  • the two electrodes are tubular and coaxial, in extension of one another, and they are each arranged in a support.
  • a cooling circuit is necessarily provided between each electrode and the support which surrounds it because of the temperatures reached.
  • means are provided for striking said arc, which may be of the type with electric discharge produced between the two electrodes or of the short-circuit type, thanks, for example, to the use of an auxiliary starting electrode.
  • the torches most often comprise at least one electromagnetic coil arranged around one of the electrode supports, to allow the displacement of the attachment feet of the electric arc and, thus, to avoid premature wear of the internal surfaces of the tubular electrodes .
  • the means for injecting plasma gas such as air
  • they generally comprise a part of revolution coaxial with said electrodes and defining with these and their supports said injection chamber.
  • Transverse orifices are provided in the room to allow the injection of plasma gas, from a supply circuit, into the chamber.
  • said part is made of a metallic material and also comprises a cooling circuit.
  • longitudinal passages for cooling fluid circulation are provided in the part of revolution.
  • these passages communicate on one side with an external annular groove formed in the part, into which the cooling fluid arrives, and, on the other side, these passages are placed in communication with the cooling circuit of the downstream electrode (relative to the circulation of plasma gas). Thanks to this, the same cooling fluid flows through the cooling circuits of the injection part and of the downstream electrode.
  • insulating members are provided between the injection part and the upstream electrode, which, moreover, can have a role of thermal shield for the upstream or rear part of the torch.
  • the present invention relates to a plasma torch which, taking into account the unexpected results revealed by the various tests carried out, presents a considerably simplified embodiment while guaranteeing performances similar to plasma torches of the prior art.
  • the part of revolution is very easy to produce, injection orifices being only made by drilling in said part.
  • the injection part since the injection part is not subjected to high temperatures, it need not be made of metal. However, as the injection piece is more insulating, it is no longer also necessary to provide the insulation and thermal shield devices previously arranged between the two electrodes and which involved a significant additional bulk of the torch.
  • the part of revolution can then be made of a plastic material such as, for example, a polytetrafluoroethylene.
  • the part of revolution can have a section in the shape of a crown.
  • the plasma gas injection orifices are regularly distributed around said part.
  • the geometric axes of the transverse injection orifices contained in planes perpendicular to the longitudinal axis of the torch, instead of converging towards the latter , are slightly offset from their position for which they would converge towards said longitudinal axis.
  • Figure 1 is a longitudinal sectional view of an embodiment of the plasma torch according to the invention.
  • Figure 2 shows, in cutaway perspective, said plasma gas injection part.
  • the plasma torch 1 comprises a body 2 comprising in particular two cylindrical supports 3 and 4. Inside the support 3 is housed an upstream electrode or cathode 5, while inside the support 4 is housed a downstream electrode or anode 6. These electrodes 5 and 6 have a tubular shape and they are arranged coaxially to a longitudinal axis 7 while being spaced from one another along said axis. These electrodes are connected to power supplies, not shown.
  • each support and its corresponding electrode is formed a cooling circuit, respectively 8 and 9, in which a cooling fluid circulates. Only the input, respectively 8A and 9A, of these cooling circuits has been shown.
  • the structure of these electrode cooling circuits which is of a known type, will not be described further, these circuits being connected to a supply of cooling fluid.
  • an auxiliary starting electrode 12 is provided in this embodiment.
  • an electromagnetic coil 14 is arranged around the support 3 of the upstream electrode 5, so to allow, under the action of the axial magnetic field which it generates, the displacement of the feet of the electric arc 11 around the internal surfaces 5A and 6A, respectively of the electrodes 5 and 6, thereby avoiding premature wear of the latter.
  • the plasma torch 1 also comprises means 16 for injecting a plasma gas, such as air, between the electrodes 5 and 6 as soon as the electric arc 11 is produced.
  • a plasma gas such as air
  • These means 16 comprise a part of revolution 17 having a section in the form of a crown and surrounding the opposite ends 58 and 68 respectively of the electrodes 5 and 6.
  • the internal wall 17A of the part 17, the ends 58 and 68 of the electrodes and the front face 3A of the support 3 define an internal chamber 18, into which the plasma gas is injected by means of transverse orifices 17B formed in the injection part 17.
  • the plasma gas comes from a supply, not shown, and arrives at 19 in an annular space 20 delimited between an external envelope 21 of the body 2 of the torch and the external wall 17C of the injection piece 17.
  • the injection part 17 according to the invention is devoid of internal cooling means. Indeed, the cold plasma gas injected into the chamber 18 constitutes, in the vicinity of the internal wall 17A of the injection part, a protective thermal barrier against the high temperatures generated by the electric arc 11, at the heart of the chamber 18. It therefore follows that the production of the injection piece 17, as shown more particularly in FIG. 2, is considerably simplified. Indeed, the drilling of the injection orifices 17B regularly distributed around the part 17 does not raise any difficulties.
  • the injection part can be made of a plastic material, preferably electrically insulating such as, for example, a polytetrafluoroethylene.
  • This plastic part can also play the role of electrical insulator between the two electrodes 5 and 6, so that it is no longer necessary to provide insulation and thermal shield devices usually fitted to the plasma torches of the prior art.
  • Figure 1 highlights the small footprint of the plasma torch obtained according to the invention.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Plasma Technology (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Arc Welding Control (AREA)
  • Treatments Of Macromolecular Shaped Articles (AREA)

Abstract

The present invention relates to a plasma torch of the type comprising: - two tubular and coaxial electrodes (5 and 6), one a continuation of the other, each of them being arranged in a holder (3 and 4) in which there is provision for a cooling circuit (8 and 9) for the corresponding electrode; - means (12) for producing an initiating of an electric arc between the two electrodes, and, - means (16) for injecting a plasma-forming gas between said electrodes, comprising a component of revolution (17) coaxial with the said electrodes and defining with the latter and their holders a chamber (18) in which, by virtue of transverse orifices (17B) made in the component, the plasma-forming gas is injected. According to the invention, the said component of revolution (17) is devoid of internal means of cooling. <IMAGE>

Description

La présente invention concerne les torches à plasma d'arc électrique, mettant en oeuvre l'injection d'un gaz plasmagène dans une chambre interne, qui est ménagée dans la torche et qui est traversée par un arc électrique engendré entre deux électrodes. Les températures atteintes par le plasma en sortie de la torche peuvent dépasser les 10 000°C.The present invention relates to electric arc plasma torches, implementing the injection of a plasma gas into an internal chamber, which is formed in the torch and which is crossed by an electric arc generated between two electrodes. The temperatures reached by the plasma leaving the torch can exceed 10,000 ° C.

Dans les réalisations usuelles des torches à plasma (voir EP-A-289.423), les deux électrodes sont tubulaires et coaxiales, en prolongement l'une de l'autre, et elles sont chacune disposées dans un support. Un circuit de refroidissement est nécessairement ménagé entre chaque électrode et le support qui l'entoure en raison des températures atteintes. Par ailleurs, pour produire l'arc électrique entre les électrodes, on prévoit des moyens pour amorcer ledit arc, qui peuvent être du type à décharge électrique produite entre les deux électrodes ou du type à court-circuit, grâce, par exemple, à l'utilisation d'une électrode auxiliaire de démarrage. Les torches comprennent le plus souvent au moins une bobine électromagnétique disposée autour d'un des supports d'électrode, pour permettre le déplacement des pieds d'accrochage de l'arc électrique et, ainsi, éviter une usure prématurée des surfaces internes des électrodes tubulaires.In the usual embodiments of plasma torches (see EP-A-289.423), the two electrodes are tubular and coaxial, in extension of one another, and they are each arranged in a support. A cooling circuit is necessarily provided between each electrode and the support which surrounds it because of the temperatures reached. Furthermore, to produce the electric arc between the electrodes, means are provided for striking said arc, which may be of the type with electric discharge produced between the two electrodes or of the short-circuit type, thanks, for example, to the use of an auxiliary starting electrode. The torches most often comprise at least one electromagnetic coil arranged around one of the electrode supports, to allow the displacement of the attachment feet of the electric arc and, thus, to avoid premature wear of the internal surfaces of the tubular electrodes .

Quant aux moyens d'injection du gaz plasmagène, tel que de l'air, dans la chambre interne de la torche, ils comprennent généralement une pièce de révolution coaxiale auxdites électrodes et définissant avec celles-ci et leurs supports ladite chambre d'injection.As for the means for injecting plasma gas, such as air, into the internal chamber of the torch, they generally comprise a part of revolution coaxial with said electrodes and defining with these and their supports said injection chamber.

Des orifices transversaux sont prévus dans la pièce pour autoriser l'injection du gaz plasmagène, issu d'un circuit d'alimentation, dans la chambre. Comme la pièce est directement exposée au rayonnement thermique engendré par l'arc électrique et à la réaction chimique qui s'ensuit avec le gaz plasmagène, ladite pièce est réalisée en une matière métallique et comporte, par ailleurs, un circuit de refroidissement. Pour cela, des passages longitudinaux de circulation de fluide de refroidissement sont ménagés dans la pièce de révolution. Par exemple, ces passages communiquent d'un côté avec une gorge annulaire externe ménagée dans la pièce, dans laquelle arrive le fluide de refroidissement, et, de l'autre côté, ces passages sont mis en communication avec le circuit de refroidissement de l'électrode aval (par rapport à la circulation du gaz plasmagène). Grâce à cela, le même fluide de refroidissement parcourt les circuits de refroidissement de la pièce d'injection et de l'électrode aval.Transverse orifices are provided in the room to allow the injection of plasma gas, from a supply circuit, into the chamber. As the part is directly exposed to the thermal radiation generated by the electric arc and the chemical reaction which follows with the plasma gas, said part is made of a metallic material and also comprises a cooling circuit. For this, longitudinal passages for cooling fluid circulation are provided in the part of revolution. For example, these passages communicate on one side with an external annular groove formed in the part, into which the cooling fluid arrives, and, on the other side, these passages are placed in communication with the cooling circuit of the downstream electrode (relative to the circulation of plasma gas). Thanks to this, the same cooling fluid flows through the cooling circuits of the injection part and of the downstream electrode.

Cependant, comme la pièce d'injection est métallique et, par conséquent, conductrice d'électricité, il est impératif de prévoir un dispositif électriquement isolant afin de garantir une isolation maximale entre les deux électrodes. A cet effet, on prévoit des organes isolants entre la pièce d'injection et l'électrode amont, qui, en outre, peuvent avoir un rôle d'écran thermique pour la partie amont ou arrière de la torche.However, as the injection piece is metallic and therefore electrically conductive, it is imperative to provide an electrically insulating device in order to guarantee maximum insulation between the two electrodes. To this end, insulating members are provided between the injection part and the upstream electrode, which, moreover, can have a role of thermal shield for the upstream or rear part of the torch.

On comprend donc les inconvénients engendrés par ces torches à plasma et portant principalement, à cause des températures atteintes, sur la réalisation complexe de la pièce d'injection du gaz plasmagène, pourvue d'un circuit de refroidissement interne, et sur la nécessité d'adjoindre, pour les raisons évoquées préalablement, des organes isolants qui impliquent une augmentation de l'encombrement des torches à plasma, ainsi que de leur coût.We therefore understand the drawbacks generated by these plasma torches and mainly, because of the temperatures reached, on the complex production of the plasma gas injection part, provided with an internal cooling circuit, and on the need to add, for the reasons mentioned above, insulating members which involve an increase in the size of the plasma torches, as well as their cost.

La Demanderesse a donc cherché à remédier à ces inconvénients en pratiquant pour cela sur une torche à plasma du type décrit ci-dessus divers essais sur la pièce d'injection afin d'étudier son comportement en fonction des températures rencontrées.The Applicant has therefore sought to remedy these drawbacks by practicing for this on a plasma torch of the type described above various tests on the injection part in order to study its behavior as a function of the temperatures encountered.

Les résultats de ces essais ont montré que la pièce d'injection ne subissait pas des températures aussi élevées que l'on pensait. Ces résultats ont prouvé que la température du fluide de refroidissement à la sortie des passages longitudinaux était peu différente de celle relevée à l'entrée desdits passages. La Demanderesse en a donc déduit que le gaz plasmagène frais, injecté de façon continue à travers les orifices en direction de la chambre, constituait une couche thermiquement protectrice efficace pour la paroi interne de la pièce d'injection, vis-à-vis de la température régnant au coeur de la chambre, c'est-à-dire au niveau de l'arc électrique.The results of these tests showed that the injection room was not subjected to temperatures as high as expected. These results have shown that the temperature of the cooling fluid at the outlet of the longitudinal passages was little different from that recorded at the inlet of said passages. The Applicant has therefore deduced therefrom that the fresh plasma gas, injected continuously through the orifices towards the chamber, constituted an effective thermally protective layer for the internal wall of the injection part, vis-à-vis the temperature prevailing in the heart of the room, that is to say at the level of the electric arc.

Par conséquent, la présente invention concerne une torche à plasma qui, en tenant compte des résultats inattendus révélés par les différents essais effectués, présente une réalisation considérablement simplifiée tout en garantissant des performances analogues aux torches à plasma de l'art antérieur.Consequently, the present invention relates to a plasma torch which, taking into account the unexpected results revealed by the various tests carried out, presents a considerably simplified embodiment while guaranteeing performances similar to plasma torches of the prior art.

A cet effet, la torche à plasma, du type comprenant :

  • deux électrodes tubulaires et coaxiales, en prolongement l'une de l'autre, chacune d'elles étant agencée dans un support dans lequel est ménagé un circuit de refroidissement de l'électrode correspondante ;
  • des moyens pour produire l'amorçage d'un arc électrique entre les deux électrodes ; et,
  • des moyens pour injecter un gaz plasmagène entre lesdites électrodes, comprenant une pièce de révolution coaxiale auxdites électrodes et définissant avec celles-ci et leurs supports une chambre, dans laquelle est injecté, grâce à des orifices transversaux pratiqués dans la pièce, le gaz plasmagène,

est remarquable, selon l'invention, en ce que ladite pièce de révolution est dépourvue de circuit de refroidissement et est réalisée en une matière non métallique, isolante électriquement.For this purpose, the plasma torch, of the type comprising:
  • two tubular and coaxial electrodes, in extension of one another, each of them being arranged in a support in which is formed a cooling circuit of the corresponding electrode;
  • means for generating an electric arc between the two electrodes; and,
  • means for injecting a plasma gas between said electrodes, comprising a part of revolution coaxial with said electrodes and defining with these and their supports a chamber, into which is injected, by means of transverse orifices made in the part, the plasma gas,

is remarkable, according to the invention, in that said piece of revolution has no cooling circuit and is made of a non-metallic material, electrically insulating.

Ainsi, grâce aux résultats inattendus des essais, la pièce de révolution, usuellement complexe, est d'une réalisation très aisée, des orifices d'injection étant uniquement pratiqués par perçage dans ladite pièce.Thus, thanks to the unexpected results of the tests, the part of revolution, usually complex, is very easy to produce, injection orifices being only made by drilling in said part.

En effet, puisque la pièce d'injection n'est pas soumise à des températures élevées, il n'est pas nécessaire qu'elle soit en métal. Or, comme la pièce d'injection est de plus isolante, il n'est plus nécessaire également de prévoir les dispositifs d'isolation et d'écran thermique préalablement agencés entre les deux électrodes et qui impliquaient un encombrement supplémentaire important de la torche.In fact, since the injection part is not subjected to high temperatures, it need not be made of metal. However, as the injection piece is more insulating, it is no longer also necessary to provide the insulation and thermal shield devices previously arranged between the two electrodes and which involved a significant additional bulk of the torch.

On comprend donc de ce qui précède que la réalisation de la torche se trouve considérablement simplifiée.It is therefore understood from the above that the production of the torch is considerably simplified.

La pièce de révolution peut être alors réalisée en une matière plastique telle que, par exemple, un polytétrafluoroéthylène.The part of revolution can then be made of a plastic material such as, for example, a polytetrafluoroethylene.

Structurellement, la pièce de révolution peut présenter une section en forme de couronne. De préférence, les orifices d'injection du gaz plasmagène sont régulièrement répartis autour de ladite pièce.Structurally, the part of revolution can have a section in the shape of a crown. Preferably, the plasma gas injection orifices are regularly distributed around said part.

Par ailleurs, afin d'assurer un effet de vortex au gaz plasmagène injecté dans la chambre, les axes géométriques des orifices transversaux d'injection, contenus dans des plans perpendiculaires à l'axe longitudinal de la torche, au lieu de converger vers ce dernier, sont légèrement décalés par rapport à leur position pour laquelle ils convergeraient vers ledit axe longitudinal.Furthermore, in order to ensure a vortex effect on the plasma gas injected into the chamber, the geometric axes of the transverse injection orifices, contained in planes perpendicular to the longitudinal axis of the torch, instead of converging towards the latter , are slightly offset from their position for which they would converge towards said longitudinal axis.

Les figures du dessin annexé feront bien comprendre comment l'invention peut être réalisée. Sur ces figures, des références identiques désignent des éléments semblables.The figures of the appended drawing will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

La figure 1 est une vue en coupe longitudinale d'un exemple de réalisation de la torche à plasma selon l'invention.Figure 1 is a longitudinal sectional view of an embodiment of the plasma torch according to the invention.

La figure 2 montre, en perspective écorchée, ladite pièce d'injection du gaz plasmagène.Figure 2 shows, in cutaway perspective, said plasma gas injection part.

En se référant à la figure 1, la torche à plasma 1 comporte un corps 2 comprenant notamment deux supports cylindriques 3 et 4. A l'intérieur du support 3 est logée une électrode amont ou cathode 5, tandis qu'à l'intérieur du support 4 est logée une électrode aval ou anode 6. Ces électrodes 5 et 6 présentent une forme tubulaire et elles sont disposées coaxialement à un axe longitudinal 7 en étant espacées l'une de l'autre le long dudit axe. Ces électrodes sont reliées à des alimentations électriques non représentées.Referring to FIG. 1, the plasma torch 1 comprises a body 2 comprising in particular two cylindrical supports 3 and 4. Inside the support 3 is housed an upstream electrode or cathode 5, while inside the support 4 is housed a downstream electrode or anode 6. These electrodes 5 and 6 have a tubular shape and they are arranged coaxially to a longitudinal axis 7 while being spaced from one another along said axis. These electrodes are connected to power supplies, not shown.

Par ailleurs, entre chaque support et son électrode correspondante est ménagé un circuit de refroidissement, respectivement 8 et 9, dans lequel circule un fluide de refroidissement. Seule l'entrée, respectivement 8A et 9A, de ces circuits de refroidissement a été représentée. On ne décrira pas davantage la structure de ces circuits de refroidissement des électrodes qui est d'un type connu, ces circuits étant reliés à une alimentation en fluide de refroidissement.Furthermore, between each support and its corresponding electrode is formed a cooling circuit, respectively 8 and 9, in which a cooling fluid circulates. Only the input, respectively 8A and 9A, of these cooling circuits has been shown. The structure of these electrode cooling circuits, which is of a known type, will not be described further, these circuits being connected to a supply of cooling fluid.

Pour amorcer l'arc électrique 11 entre les deux électrodes et 6, on prévoit dans ce mode de réalisation une électrode auxiliaire de démarrage 12. De plus, une bobine électromagnétique 14 est disposée autour du support 3 de l'électrode amont 5, de façon à permettre, sous l'action du champ magnétique axial qu'elle engendre, le déplacement des pieds de l'arc électrique 11 autour des surfaces internes 5A et 6A, respectivement des électrodes 5 et 6, évitant de la sorte une usure prématurée de ces dernières.To initiate the electric arc 11 between the two electrodes and 6, an auxiliary starting electrode 12 is provided in this embodiment. In addition, an electromagnetic coil 14 is arranged around the support 3 of the upstream electrode 5, so to allow, under the action of the axial magnetic field which it generates, the displacement of the feet of the electric arc 11 around the internal surfaces 5A and 6A, respectively of the electrodes 5 and 6, thereby avoiding premature wear of the latter.

La torche à plasma 1 comprend par ailleurs des moyens 16 pour injecter un gaz plasmagène, tel que de l'air, entre les électrodes 5 et 6 dès que l'arc électrique 11 est produit. Ces moyens 16 comprennent une pièce de révolution 17 présentant une section en forme de couronne et entourant les extrémités en regard 58 et 68 respectivement des électrodes 5 et 6. Ainsi, dans ce mode de réalisation, la paroi interne 17A de la pièce 17, les extrémités 58 et 68 des électrodes et la face avant 3A du support 3 définissent une chambre interne 18, dans laquelle est injecté le gaz plasmagène grâce à des orifices transversaux 17B ménagés dans la pièce 17 d'injection.The plasma torch 1 also comprises means 16 for injecting a plasma gas, such as air, between the electrodes 5 and 6 as soon as the electric arc 11 is produced. These means 16 comprise a part of revolution 17 having a section in the form of a crown and surrounding the opposite ends 58 and 68 respectively of the electrodes 5 and 6. Thus, in this embodiment, the internal wall 17A of the part 17, the ends 58 and 68 of the electrodes and the front face 3A of the support 3 define an internal chamber 18, into which the plasma gas is injected by means of transverse orifices 17B formed in the injection part 17.

Le gaz plasmagène est issu d'une alimentation non représentée et parvient en 19 dans un espace annulaire 20 délimité entre une enveloppe externe 21 du corps 2 de la torche et la paroi externe 17C de la pièce d'injection 17.The plasma gas comes from a supply, not shown, and arrives at 19 in an annular space 20 delimited between an external envelope 21 of the body 2 of the torch and the external wall 17C of the injection piece 17.

Pour les raisons évoquées préalablement, la pièce d'injection 17, selon l'invention, est dépourvue de moyens de refroidissement internes. En effet, le gaz plasmagène froid injecté dans la chambre 18 constitue, au voisinage de la paroi interne 17A de la pièce d'injection, une barrière thermique protectrice à l'encontre des températures élevées engendrées par l'arc électrique 11, au coeur de la chambre 18. Il s'ensuit donc que la réalisation de la pièce d'injection 17, comme le montre plus particulièrement la figure 2, s'en trouve considérablement simplifiée. En effet, le perçage des orifices d'injection 17B régulièrement répartis autour de la pièce 17 ne soulève pas de difficultés.For the reasons mentioned above, the injection part 17 according to the invention is devoid of internal cooling means. Indeed, the cold plasma gas injected into the chamber 18 constitutes, in the vicinity of the internal wall 17A of the injection part, a protective thermal barrier against the high temperatures generated by the electric arc 11, at the heart of the chamber 18. It therefore follows that the production of the injection piece 17, as shown more particularly in FIG. 2, is considerably simplified. Indeed, the drilling of the injection orifices 17B regularly distributed around the part 17 does not raise any difficulties.

On remarquera sur la figure 2 que les axes géométriques 17D des orifices d'injection 17B, contenus dans des plans perpendiculaires à l'axe longitudinal de la pièce 17 correspondant à l'axe longitudinal 7 de la torche, sont légèrement décalés par rapport à la position pour laquelle ils convergeraient vers celui-ci. Cette orientation décalée des orifices d'injection 17B permet d'assurer avantageusement un effet de vortex au gaz plasmagène injecté dans la chambre 18.It will be noted in FIG. 2 that the geometric axes 17D of the injection orifices 17B, contained in planes perpendicular to the longitudinal axis of the part 17 corresponding to the longitudinal axis 7 of the torch, are slightly offset with respect to the position for which they would converge towards this one. This offset orientation of the injection orifices 17B advantageously ensures a vortex effect on the plasma gas injected into the chamber 18.

Comme la pièce d'injection n'est pas soumise à des températures élevées, elle peut être réalisée en une matière plastique, de préférence électriquement isolante telle que, par exemple, un polytétrafluoroéthylène. Cette pièce en matière plastique peut jouer, de plus, le rôle d'isolant électrique entre les deux électrodes 5 et 6, de sorte qu'il n'est plus nécessaire de prévoir de dispositifs d'isolation et d'écran thermique équipant usuellement les torches à plasma de l'art antérieur.As the injection part is not subjected to high temperatures, it can be made of a plastic material, preferably electrically insulating such as, for example, a polytetrafluoroethylene. This plastic part can also play the role of electrical insulator between the two electrodes 5 and 6, so that it is no longer necessary to provide insulation and thermal shield devices usually fitted to the plasma torches of the prior art.

La figure 1 permet de mettre en valeur le faible encombrement de la torche à plasma obtenue selon l'invention.Figure 1 highlights the small footprint of the plasma torch obtained according to the invention.

Claims (6)

  1. Plasma torch of the type comprising:
    - two tubular and coaxial electrodes (5 and 6), in extension of one another, each of them being arranged in a support (3 and 4) in which a circuit (8 and 9) for cooling the corresponding electrode is made;
    - means (12) for initiating an electric arc between the two electrodes; and
    - means (16) for injecting a plasma-generating gas between the said electrodes, comprising an axisymmetric part (17) coaxial with the said electrodes and defining a chamber (18) with these and their supports, in which the plasma-generating gas is injected by virtue of transverse orifices (17B) made in the part; characterized in that the said axisymmetric part (17) has no cooling circuit and is made of an electrically insulating non-metallic material.
  2. Plasma torch according to Claim 1, characterized in that the said axisymmetric part (17) is made of a plastic.
  3. Plasma torch according to Claim 2, characterized in that the plastic is a polytetrafluoroethylene.
  4. Plasma torch according to any one of the preceding Claims 1 to 3, characterized in that the axisymmetric part (17) has a ring-shaped cross-section.
  5. Plasma torch according to one of the preceding Claims 1 to 4, characterized in that the orifices (17B) for injection of the plasma-generating gas are regularly distributed around the said part (17).
  6. Plasma torch according to any one of Claims 1 to 5, characterized in that the geometrical axes (17D) of the transverse orifices (17B) for injecting the plasma-generating gas, contained in planes perpendicular to the longitudinal axis (7) of the torch, instead of converging towards the latter are slightly offset with respect to their position in which they would converge towards the said longitudinal axis (7)
EP90403045A 1989-11-08 1990-10-29 Plasma torch with non-cooled plasma gas injection Expired - Lifetime EP0427591B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8914676 1989-11-08
FR8914676A FR2654293B1 (en) 1989-11-08 1989-11-08 PLASMA TORCH WITH UNCOOLED INJECTION GAS PLASMAGEN.

Publications (2)

Publication Number Publication Date
EP0427591A1 EP0427591A1 (en) 1991-05-15
EP0427591B1 true EP0427591B1 (en) 1994-11-30

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Application Number Title Priority Date Filing Date
EP90403045A Expired - Lifetime EP0427591B1 (en) 1989-11-08 1990-10-29 Plasma torch with non-cooled plasma gas injection

Country Status (9)

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EP (1) EP0427591B1 (en)
JP (1) JP3006771B2 (en)
KR (1) KR0146044B1 (en)
AT (1) ATE114928T1 (en)
CA (1) CA2029505C (en)
DE (1) DE69014561T2 (en)
DK (1) DK0427591T3 (en)
ES (1) ES2067000T3 (en)
FR (1) FR2654293B1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2734445B1 (en) * 1995-05-19 1997-07-18 Aerospatiale CONTINUOUS CURRENT ARC PLASMA TORCH, ESPECIALLY INTENDED FOR OBTAINING A CHEMICAL BODY BY DECOMPOSITION OF A PLASMAGEN GAS
CH690408A5 (en) * 1996-02-23 2000-08-31 Mgc Plasma Ag Plasma torch for transferred arc.
DE19835224A1 (en) * 1998-08-05 2000-02-10 Stefan Laure Plasma generator for production of directed plasma jet
JP4568503B2 (en) * 2004-01-20 2010-10-27 小池酸素工業株式会社 Plasma torch
KR101249457B1 (en) * 2012-05-07 2013-04-03 지에스플라텍 주식회사 Plasma torch of non-transferred and hollow type

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2207961A1 (en) * 1972-11-27 1974-06-21 G N Carbon prodn by pyrolysis - in a plasma using hydrocarbon gas
US4549065A (en) * 1983-01-21 1985-10-22 Technology Application Services Corporation Plasma generator and method
BE898951A (en) * 1984-02-17 1984-08-17 Centre Rech Metallurgique ELECTRIC ARC PLASMA TORCH.
CA1261927A (en) * 1985-11-25 1989-09-26 Hypertherm, Inc. Underwater and above-water plasma arc cutting torch and method

Also Published As

Publication number Publication date
ES2067000T3 (en) 1995-03-16
KR910011093A (en) 1991-06-29
CA2029505A1 (en) 1991-05-09
KR0146044B1 (en) 1998-08-17
DE69014561T2 (en) 1995-04-06
CA2029505C (en) 2000-08-15
ATE114928T1 (en) 1994-12-15
FR2654293A1 (en) 1991-05-10
FR2654293B1 (en) 1996-05-24
EP0427591A1 (en) 1991-05-15
JP3006771B2 (en) 2000-02-07
JPH03173099A (en) 1991-07-26
DK0427591T3 (en) 1995-02-27
DE69014561D1 (en) 1995-01-12

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