EP2563100A1 - Nozzle for a fluid-cooled plasma torch and plasma torch head with same - Google Patents

Abstract

The nozzle has a nozzle hole (4.10) for discharging plasma gas beam to a nozzle tip (4.11) and comprising a section (4.1) with a cylindrical outer surface (4.4) and another section (4.2) with a tapered outer surface (4.5). A cooling fluid supply groove (4.20) extends over a part of the former section and over the latter surface towards the nozzle tip. A cooling fluid return groove (4.22) is arranged separately from the liquid supply groove, and extends over the latter section. Outwardly projecting areas (4.31, 4.32) are formed between the supply and return grooves. An independent claim is also included for a plasma torch head.

Description

The present invention relates to a nozzle for a liquid-cooled plasma torch, a nozzle cap for a liquid-cooled plasma torch, and a plasma torch head having the same.

Plasma is a thermally highly heated electrically conductive gas, which consists of positive and negative ions, electrons and excited and neutral atoms and molecules.

The plasma gas used is a variety of gases, for example the monatomic argon and / or the diatomic gases hydrogen, nitrogen, oxygen or air. These gases ionize and dissociate through the energy of an arc. The narrowed by a nozzle arc is then referred to as plasma jet.

The plasma jet can be greatly influenced in its parameters by the design of the nozzle and electrode. These parameters of the plasma jet are, for example, the beam diameter, the temperature, the energy density and the flow velocity of the gas.

In plasma cutting, for example, the plasma is constricted through a nozzle, which may be gas or water cooled. As a result, energy densities up to 2x10 ⁶ W / cm ² can be achieved. Temperatures of up to 30,000 ° C are generated in the plasma jet, which, in combination with the high flow velocity of the gas, produce very high cutting speeds on materials.

Plasma torches can be operated directly or indirectly. In the direct mode of operation, the current from the power source flows through the electrode of the plasma torch, the arc generated by the arc and constricted by the nozzle directly back to the power source via the workpiece. With the direct mode of operation, electrically conductive materials can be cut.

In the indirect mode, the current flows from the power source through the electrode of the plasma torch, the plasma jet generated by the arc and constricted by the nozzle and the nozzle back to the power source. The nozzle is even more heavily loaded than with direct plasma cutting, because it not only constricts the plasma jet, but also realizes the starting point of the arc. With the indirect mode of operation, both electrically conductive and non-conductive materials can be cut.

Because of the high thermal load of the nozzle, this is usually made of a metallic material, preferably because of its high electrical conductivity and thermal conductivity of copper. The same applies to the electrode holder, which can also be made of silver. The nozzle is then inserted into a plasma torch whose main components are a plasma torch head, a nozzle cap, a plasma gas guide member, a nozzle, a nozzle holder, an electrode holder, an electrode holder with electrode insert and in modern plasma torches a nozzle cap holder and a nozzle cap. The electrode holder fixes a tungsten tip insert which is suitable for the use of non-oxidizing gases as plasma gas, for example an argon-hydrogen mixture. A so-called flat electrode, whose electrode insert consists for example of hafnium, is also suitable for the use of oxidizing gases as plasma gas, for example air or oxygen. In order to achieve a long service life for the nozzle, it is cooled here with a liquid, for example water. The coolant is directed towards the nozzle via a water feed and a water return from the nozzle and flows through a coolant space which is delimited by the nozzle and the nozzle cap.

In DD 36014 B1 a nozzle is described. This consists of a highly conductive material, for example copper, and has a geometric shape associated with the respective plasma torch type, for example a conical discharge space with a cylindrical nozzle exit. The outer shape of the nozzle is formed as a cone, wherein an approximately equal wall thickness is achieved, which is dimensioned so that a good stability of the nozzle and a good heat conduction to the coolant is ensured. The nozzle sits in a nozzle holder. The nozzle holder is made of corrosion-resistant material, such as brass, and has inside a centering for the nozzle and a groove for a rubber seal, which seals the discharge space against the coolant. Furthermore, there are 180 ° staggered holes in the nozzle holder for the coolant supply and return. On the outer diameter of the nozzle holder there is a groove for a round rubber for sealing the coolant space from the atmosphere and a thread and a centering for a nozzle cap. The nozzle cap, also made of corrosion-resistant material, such as brass, is formed at an acute angle and has a useful for the dissipation of radiant heat to the coolant wall thickness. The smallest inner diameter is provided with a round ring. The easiest way to cool water is to use water. This arrangement is intended to allow easy production of the nozzles with economical use of material and rapid replacement of these and by the acute-angled design pivoting of the plasma torch relative to the workpiece and thus bevel cuts.

In DE-OS 1 565 638 a plasma torch, preferably for plasma cutting of materials and for welding edge preparation is described. The slim shape of the Burner head is achieved by the use of a particularly acute-angled cutting nozzle whose inner and outer angles are equal to each other and equal to the inner and outer angle of the nozzle cap. Between the nozzle cap and the cutting nozzle, a coolant space is formed, in which the nozzle cap is provided with a collar, which seals with the metal cutting nozzle, thereby creating a uniform annular gap as the coolant space. The supply and discharge of the coolant, generally water, is carried out by two 180 ° offset from each other arranged slots in the nozzle holder.

In DE 25 25 939 a plasma arc torch, in particular for cutting or welding, is described, in which the electrode holder and the nozzle body form an exchangeable structural unit. The outer coolant supply is essentially formed by a comprehensive the nozzle body cap. The coolant flows via channels into an annular space, which is formed by the nozzle body and the cap.

DE 692 33 071 T2 relates to an arc plasma cutting device. Described herein is an embodiment of a plasma arc cutting nozzle nozzle formed of a conductive material and having a plasma jet jet exit and a hollow body portion configured to have a generally conical thin-walled configuration that extends in the direction is inclined to the outlet opening and has an enlarged head portion, which is formed integrally with the body portion, wherein the head portion is solid except for a central channel which is aligned with the outlet opening and having a generally conical outer surface, which is also in the direction of the outlet opening is inclined and has a diameter adjacent to that of the adjacent body portion exceeding the diameter of the body portion to form a recessed recess. The arc plasma cutter has a secondary gas cap. Further, a water-cooled cap is disposed between the nozzle and the secondary gas cap to form a water-cooled chamber for the outer surface of the nozzle for highly efficient cooling. The nozzle is characterized by a large head surrounding an exit port for the plasma jet and a sharp undercut or recess to a conical body. This nozzle design favors the cooling of the nozzle.

In the plasma torches described above, the coolant is led back to the nozzle via a water feed channel and away from the nozzle via a water return channel. These channels are usually offset by 180 ° to each other and the coolant should flow around the nozzle as evenly as possible on the way from the flow to the return. Nevertheless, overheating in the vicinity of the nozzle channel are repeatedly found.

Another coolant guide for a burner, preferably plasma torches, in particular for plasma welding, plasma cutting, plasma melting and plasma spraying, which withstands high thermal stresses on the nozzle and the cathode is disclosed in US Pat DD 83890 B1 described. Here is for cooling the nozzle in the nozzle holding part easily deployable and removable Kühlmedienleitring arranged to limit the cooling media on a thin layer of a maximum thickness of 3 mm along the outer nozzle wall has a circumferential Formnut, in the more than one, preferably two to four, and star-shaped to this radially and symmetrically to the nozzle axis and star connected to this at an angle between 0 and 90 ° mounted cooling lines so that it is adjacent by two cooling media outlets and each cooling medium outflow of two cooling medium inflows.

This arrangement in turn has the disadvantage that a higher outlay for the cooling by the use of an additional component, the Kühlmedienleitring, is necessary. In addition, this increases the entire arrangement.

The invention is therefore based on the object to avoid overheating in the vicinity of the nozzle channel or the nozzle bore in a simple manner.

• eine Düse nach einem der Ansprüche 1 bis 19,
• eine Düsenhalterung zur Halterung der Düse, und

eine Düsenkappe, vorzugsweise nach einem der Ansprüche 20 bis 22, wobei die Düsenkappe und die Düse einen Kühlflüssigkeitsraum bilden, der über zwei jeweils um 60° bis 180° versetzte Bohrungen mit einer Kühlflüssigkeitszulaufleitung bzw. Kühlflüssigkeitsrücklaufleitung verbindbar ist, wobei die Düsenhalterung so gestaltet ist, dass die Kühlflüssigkeit nahezu senkrecht zur Längsachse des Plasmabrennerkopfes auf die Düse treffend in den Kühlflüssigkeitsraum und/oder nahezu senkrecht zur Längsachse aus dem Kühlflüssigkeitsraum in die Düsenhalterung gelangt.According to the invention, this object is achieved by a plasma burner head, comprising:

• A nozzle according to any one of claims 1 to 19,
• a nozzle holder for holding the nozzle, and

a nozzle cap, preferably according to one of claims 20 to 22, wherein the nozzle cap and the nozzle form a coolant space which is connectable via two each offset by 60 ° to 180 ° bores with a cooling liquid supply line or coolant return line, wherein the nozzle holder is designed so that the cooling liquid reaches the nozzle in the cooling liquid space and / or almost perpendicular to the longitudinal axis from the coolant liquid space into the nozzle holder almost perpendicularly to the longitudinal axis of the plasma burner head.

Further, the present invention provides a nozzle for a liquid-cooled plasma torch comprising a nozzle bore for the exit of a plasma jet at a nozzle tip, a first portion whose outer surface is substantially cylindrical, and a second portion adjoining the nozzle tip, the outer surface of which faces the nozzle tip is tapered substantially conically, wherein a) at least one Flüssigkeitszulaufnut is provided and extending over a portion of the first portion and the second portion in the outer surface of the nozzle to the nozzle tip and exactly one of the liquid or the Flüssigkeitszulaufnut (s) separate Flüssigkeitsrücklaufnut is provided and extends over the second portion, or b) exactly one Flüssigkeitszulaufnut is provided and extending over a portion of the first portion and the second portion in the outer surface of the nozzle to the nozzle tip and at least one liquid return groove separate from the liquid inlet groove is provided and extends over the second portion. By substantially cylindrical is intended to mean that the outer surface is, at least when thinking away of the grooves, such as liquid inlet and -rücklaufnuten, by and large cylindrical. In an analogous manner, "substantially conically tapered" means that the outer surface at least at Thinking away the grooves, like liquid inlet and return grooves, is tapered conically on the whole.

In addition, the present invention provides a nozzle cap for a liquid cooled plasma torch, wherein the nozzle cap has a substantially conically tapered inner surface, characterized in that the inner surface of the nozzle cap has at least two recesses in a radial plane.

According to a particular embodiment of the plasma burner head, the nozzle has one or two Kühlflüssigkeitszulaufnut (s), and the nozzle cap on its inner surface at least two, in particular exactly three, recesses whose openings facing the nozzle each extend over an arc length (b ₂ ), wherein the arc length of the circumferentially adjacent to the Kühlflüssigkeitszulaufnut (s) adjacent to the or Kühlflüssigkeitszulaufnut (s) outwardly projecting portions of the nozzle is greater than the arc length (d4, e4). In this way, a shunt from the coolant inlet to the coolant return is particularly elegant avoided.

Furthermore, it can be provided in the plasma burner head, that the two bores each extend substantially parallel to the longitudinal axis of the plasma burner head. This ensures that coolant lines can be connected to save space on the plasma burner head.

In particular, the bores for the cooling liquid inlet to the Kühflüssigkeitsrücklauf can be arranged offset by 180 °.

Advantageously, the radian dimension of the section between the recesses of the nozzle cap is at most half the size of the minimum radian measure of the coolant return groove or the minimum radian measure of the coolant inlet groove (s) of the nozzle.

Conveniently, at the nozzle, the liquid return groove (s) may also extend over a portion of the first portion in the outer surface of the nozzle.

In a particular embodiment of the nozzle, at least two liquid feed grooves are provided in case a) and at least two liquid return grooves are provided in case b).

Advantageously, the center of the Flüssigkeitszulaufnut and the center of the liquid return groove are arranged offset by 180 ° to each other over the circumference of the nozzle. In other words, the liquid inlet groove and the liquid return groove face each other.

Advantageously, in case a) the width of the liquid return groove and in case b) the width of the liquid inlet groove in the direction of contact in the range of 90 ° to 270 °. By means of such a particularly wide fluid return or inlet groove, a particularly good cooling of the nozzle can be achieved.

Conveniently, in case a) in the first portion of the nozzle there is a groove communicating with the liquid inlet groove and in case b) in the first portion of the nozzle a groove communicating with the liquid return groove.

It may be provided that in case a) the groove extends in the circumferential direction of the first portion of the nozzle over the entire circumference.

In particular, it may be provided that in case a) the groove in the circumferential direction of the first portion of the nozzle over an angle of 60 ° to 300 ° and in case b) the groove in the circumferential direction of the first portion of the nozzle over an angle in the range of 60 ° to 300 °.

In particular, it may be provided that in case a) this groove in the circumferential direction of the first portion of the nozzle over an angle in the range of 90 ° to 270 ° and in the case b) the groove extends in the circumferential direction of the first portion of the nozzle over an angle in the range of 90 ° to 270 °.

In a further embodiment of the nozzle, exactly two liquid feed grooves are provided in case a) and exactly two liquid return grooves are provided in case b).

In particular, in case a), the two liquid feed grooves may be arranged circumferentially of the nozzle symmetrical to a straight line extending from the center of the liquid return groove at right angles through the longitudinal axis of the nozzle and in case b) the two liquid return grooves symmetrical about the circumference of the nozzle are arranged to a straight line extending from the center of the Flüssigkeitszulaufnut at right angles through the longitudinal axis of the nozzle.

Advantageously, in case a) the centers of the two liquid inlet grooves and in the case b) the centers of the two liquid return grooves offset by an angle to each other over the circumference of the nozzle, which is in the range of 30 ° to 180 °.

Advantageously, in case a) the width of the liquid return groove and in case b) the width of the liquid inlet groove in the circumferential direction is in the range of 120 ° to 270 °.

In addition, it can be provided that in case a) the two liquid inlet grooves in the first section of the nozzle communicate with each other and in case b) the two liquid return grooves in the first section of the nozzle communicate with each other.

Furthermore, it can be provided that, in case a), the two liquid feed grooves in the first section of the nozzle are connected to each other by a groove and in case b) the two liquid return grooves in the first section of the nozzle are connected by a groove.

Conveniently, in case a), the groove passes over one or both of the liquid inlet grooves and in case b) the groove extends beyond one or both of the liquid return grooves.

It may be provided that in case a) the groove extends in the circumferential direction of the first portion of the nozzle over the entire circumference.

In particular, it can be provided that extends in the circumferential direction of the first portion of the nozzle over an angle in the range of 60 ° to 300 °, the groove.

In particular, it may be provided that the groove extends in the circumferential direction of the first portion of the nozzle over an angle in the range of 90 ° to 270 °.

In the nozzle cap, the recesses can be arranged equidistantly over the inner circumference in a particular embodiment.

In particular, the recesses may be semicircular in radial section.

In a particular embodiment of the plasma burner head, the two holes could each extend substantially parallel to the longitudinal axis of the plasma burner head.

Advantageously, the holes for the coolant inlet and the coolant return are arranged offset by 180 °.

The invention is based on the surprising finding that by supplying and / or removing the cooling liquid at right angles to the longitudinal axis of the plasma burner head instead of - as in the prior art - parallel to the longitudinal axis of the plasma burner head, a better cooling of the nozzle by significantly longer contact of the cooling liquid the nozzle is achieved.

If more than one Kühlflüssigkeitszulaufnut are provided, it can thus be achieved in the nozzle tip a particularly good turbulence of the cooling liquid by the meeting of the cooling liquid flows, which is usually accompanied by a better cooling of the nozzle.

Fig. 1

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse und einer Düsenkappe gemäß einer besonderen Ausführungsform der vorliegenden Erfindung

Fig. 1a

eine Schnittdarstellung entlang der Linie A-A von Fig. 1;

Fig. 1b

eine Schnittdarstellung entlang der Linie B-B von Fig. 1;

Fig. 2

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 1;

Fig. 3

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse und einer Düsenkappe gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung;

Fig. 3a

eine Schnittdarstellung entlang der Linie A-A von Fig. 3;

Fig. 3b

eine Schnittdarstellung entlang der Linie B-B von Fig. 3

Fig. 4

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 3;

Fig. 5

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse und einer Düsenkappe gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung

Fig. 5a

eine Schnittdarstellung entlang der Linie A-A von Fig. 5;

Fig. 5b

eine Schnittdarstellung entlang der Linie B-B von Fig. 5;

Fig. 6

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 5;

Fig. 7

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung;

Fig. 7a

eine Schnittdarstellung entlang der Linie A-A von Fig. 7;

Fig. 7b

eine Schnittdarstellung entlang der Linie B-B von Fig. 7;

Fig. 8

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 7;

Fig. 9

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung

Fig. 9a

eine Schnittdarstellung entlang der Linie A-A von Fig. 9;

Fig. 9b

eine Schnittdarstellung entlang der Linie B-B von Fig. 9;

Fig. 10

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 9;

Fig. 11

eine Längsschnittansicht durch einen Plasmabrennerkopf mit Plasma- und Sekundärgaszuführung mit einer Düse gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung;

Fig, 11a

eine Schnittdarstellung entlang der Linie A-A von Fig. 11;

Fig. 11b

eine Schnittdarstellung entlang der Linie B-B von Fig. 11;

Fig. 12

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) der Düse von Fig. 11;

Fig. 13

Einzeldarstellungen (links oben: Draufsicht von vorne; rechts oben: Längsschnittansicht; rechts unten: Seitenansicht) Düse gemäß einer weiteren besonderen Ausführungsform der Erfindung;

Fig. 14

Einzeldarstellungen (links: Längsschnittansicht; rechts: Draufsicht von vorne) der Düsenkappe von Fig. 1, Fig. 3 und Fig. 5 sowie Fig. 11;

Fig. 15

Einzeldarstellungen (links: Längsschnittansicht; rechts: Draufsicht von vorne) einer Düsenkappe gemäß einer besonderen Ausführungsform der Erfindung;

Fig. 16

Einzeldarstellungen (links: Längsschnittansicht; rechts: Draufsicht von vorne) einer Düsenkappe gemäß einer weiteren speziellen Ausführungsform der vorliegenden Erfindung;

Further features and advantages of the invention will become apparent from the appended claims and the following description, in which several embodiments are explained in detail with reference to the schematic drawings. Showing:

Fig. 1

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle and a nozzle cap according to a particular embodiment of the present invention

Fig. 1a

a sectional view taken along the line AA of Fig. 1 ;

Fig. 1b

a sectional view taken along the line BB of Fig. 1 ;

Fig. 2

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 1 ;

Fig. 3

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle and a nozzle cap according to another particular embodiment of the present invention;

Fig. 3a

a sectional view taken along the line AA of Fig. 3 ;

Fig. 3b

a sectional view taken along the line BB of Fig. 3

Fig. 4

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 3 ;

Fig. 5

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle and a nozzle cap according to another particular embodiment of the present invention

Fig. 5a

a sectional view taken along the line AA of Fig. 5 ;

Fig. 5b

a sectional view taken along the line BB of Fig. 5 ;

Fig. 6

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 5 ;

Fig. 7

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle according to another particular embodiment of the present invention;

Fig. 7a

a sectional view taken along the line AA of Fig. 7 ;

Fig. 7b

a sectional view taken along the line BB of Fig. 7 ;

Fig. 8

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 7 ;

Fig. 9

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle according to another particular embodiment of the present invention

Fig. 9a

a sectional view taken along the line AA of Fig. 9 ;

Fig. 9b

a sectional view taken along the line BB of Fig. 9 ;

Fig. 10

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 9 ;

Fig. 11

a longitudinal sectional view through a plasma burner head with plasma and secondary gas supply with a nozzle according to another particular embodiment of the present invention;

Fig. 11a

a sectional view taken along the line AA of Fig. 11 ;

Fig. 11b

a sectional view taken along the line BB of Fig. 11 ;

Fig. 12

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) of the nozzle of Fig. 11 ;

Fig. 13

Individual representations (top left: top view from the front, top right: longitudinal section view, bottom right: side view) nozzle according to a further particular embodiment of the invention;

Fig. 14

Individual illustrations (left: longitudinal section view, right: top view from the front) of the nozzle cap of Fig. 1 . Fig. 3 and Fig. 5 such as Fig. 11 ;

Fig. 15

Individual representations (left: longitudinal sectional view, right: top view from the front) of a nozzle cap according to a particular embodiment of the invention;

Fig. 16

Individual representations (left: longitudinal sectional view, right: plan view from the front) of a nozzle cap according to a further specific embodiment of the present invention;

In the following description, embodiments are shown which have at least one Flüssigkeitslaufnut, here referred to as Kühlflüssigkeitszulaufnut and exactly one liquid return groove, here referred to as Kühlflüssigkeitsrücklaufnut. However, the invention is not limited thereto. Just as well, the number of liquid inlet grooves and Flüssigkeitsrückaufnuten can be reversed or vice versa.

The in the FIG. 1 shown plasma burner head 1 takes with an electrode holder 6, an electrode 7 in the present case via a thread (not shown). The electrode is designed as a flat electrode. For the plasma burner, for example, air or oxygen can be used as the plasma gas (PG). A nozzle 4 is received by a substantially cylindrical nozzle holder 5. A nozzle cap 2, which is attached via a thread (not shown) to the plasma burner head 1, fixed the nozzle 4 and forms with this a cooling liquid space 10. The cooling liquid space 10 is sealed by a realized with a circular ring 4.16 seal, which is located in a groove 4.15 of the nozzle 4, between the nozzle 4 and the nozzle cap 2.

A cooling liquid, eg. As water or antifreeze added water flows through the coolant chamber 10 from a bore of the coolant flow WV to a bore of the coolant return WR, wherein the holes are arranged offset by 180 ° to each other.

In plasma torches in the prior art, overheating of the nozzle 4 in the area of the nozzle bore 4.10 always occurs. But it can also lead to overheating between the cylindrical portion of the nozzle 4 and the nozzle holder 5. This is especially true for plasma torches operated at high pilot current or indirectly. This is shown by discoloration of the copper after a short period of operation. Here, even at currents of 40A, discoloration occurs after a short time (e.g., 5 minutes). Likewise, the sealing point between nozzle 4 and nozzle cap 2 is overloaded, resulting in damage to the circular ring 4.16 and thus leakage and coolant leakage. Investigations have shown that this effect occurs especially on the side of the nozzle 4 facing the coolant return. It is assumed that the region which is subjected to the highest thermal stress, the nozzle bore 4.10 of the nozzle 4, is insufficiently cooled because the cooling liquid insufficiently flows through the part 10.20 of the cooling liquid space 10 closest to the nozzle bore and / or even on the side facing the coolant liquid return not reached.

In the present plasma torch FIG. 1 the cooling liquid is aptly directed into the cooling liquid space 10 almost perpendicular to the longitudinal axis of the plasma burner head 1 from the nozzle holder 5 to the nozzle 4. For this purpose, in a deflection space 10.10 of the cooling liquid space 10, the cooling liquid from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma burner in the direction of the first nozzle section 4.1 (s. Fig. 2 ) almost perpendicular to the longitudinal axis of the plasma burner head. 1 diverted. Thereafter, the cooling liquid flows through the coolant flowing from a Kühlflüssigkeitsvorlaufnut 4.20 (s. Fig. 1a . 1b and 2 ) of the nozzle 4 and the nozzle cap 2 formed space 10.11 in the nozzle bore 4.10 surrounding area 10.20 of the cooling liquid space 10 and flows around the nozzle 4 there. Then the cooling liquid flows through a space 10.15 formed by a cooling liquid return groove 4.22 of the nozzle 4 and the nozzle cap 2 back to the coolant return WR, the transition taking place substantially parallel to the longitudinal axis of the plasma burner head.

Furthermore, the plasma burner head 1 is equipped with a nozzle protection cap holder 8 and a nozzle protection cap 9. Through this area flows the secondary gas SG, in the plasma jet surrounds. The secondary gas SG flows through a secondary gas guide 9.1 and can be rotated by this.

Fig. 1a shows a sectional view along the line AA of the plasma torch FIG. 1 , This shows how the formed by the Kühlflüssigkeitszulaufnut 4.20 of the nozzle 4 and the nozzle cap 2 space 10.11 by sections 4.41 and 4.42 of protruding portions 4.31 and 4.32 of the nozzle 4 in combination with the inner surface 2.5 of the nozzle cap 2 prevent a shunt between the cooling liquid flow and coolant return , So that in each position of the nozzle 4 to the nozzle cap 2 to each other, the shunt of the cooling liquid is prevented, the sheet dimensions d4 and e4 of sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 must be at least as large as the radians b2 to the nozzle facing recesses 2.6 of the nozzle cap 2 (s. Fig. 14 to 16 ).

Thus, an effective cooling of the nozzle 4 is achieved in the region of the nozzle tip and prevents thermal overload. It is ensured that as much coolant as possible reaches the space 10.20 of the coolant chamber 10. There was no discoloration of the nozzle in the area of the nozzle bore 4.10 in experiments. Also leaks between the nozzle 4 and the nozzle cap 2 did not occur and the circular ring 4.16 was not overheated.

FIG. 1b includes a sectional view taken along the line B of the plasma burner head FIG. 1 , which shows the plane of the deflection 10.10.

Fig. 2 shows the nozzle 4 of the plasma burner head FIG. 1 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnut 4.20 extends over a portion of the first section 4.1 and the second section 4.2 in the outer surface 4.5 of the nozzle 4 to the nozzle tip 4.11 and ends in front of the cylindrical outer surface 4.3. The Kühlflüssigkeitsrücklaufnut 4.22 extends over the second section 4.2 of the nozzle 4. The center of the Kühlflüssigkeitszulaufnut 4.20 and the center of the Kühlflüssigkeitsrücklaufnut (4.22) are arranged offset by 180 ° to each other over the circumference of the nozzle (4). The width alpha 4 of the Kühlflüssigkeitsrücklaufnut 4.22 in the circumferential direction is about 250 °. Between the Kühlflüssigkeitsvorlaufnut 4.20 and the Kühlflüssigkeitsrücklaufnut 4.22 are the outwardly projecting areas 4.31 and 4.32 with the corresponding sections 4.41 and 4.42.

FIG. 3 shows a plasma burner similar FIG. 1 but according to another particular embodiment. The nozzle 4 has two Kühlflüssigkeitszulaufnuten 4.20 and 4.21. Again, the cooling liquid is directed almost perpendicular to the longitudinal axis of the plasma burner head 1 of the nozzle holder 5 on the nozzle 4 in the cooling liquid space 10. For this purpose, in the deflection space 10.10 of the cooling liquid space 10, the cooling liquid is deflected from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma burner in the direction of the first nozzle section 4.1 almost perpendicular to the longitudinal axis of the plasma burner head 1. Then, the cooling liquid flows through a groove 5.1 of the nozzle holder 5 in the two formed by the Kühlflüssigkeitszulaufnuten 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 spaces 10.11 and 10.12 to the nozzle bore 4.10 surrounding area 10.20 of the cooling liquid space 10 and flows around the nozzle 4 there , After that flows the Cooling liquid through the space 10.15 formed by the Kühlflüssigkeitsrücklaufnut 4.22 of the nozzle 4 and the nozzle cap 2 back to the coolant return WR, the transition here is substantially parallel to the longitudinal axis of the plasma burner head.

Fig. 3a includes a sectional view taken along the line AA of the plasma torch FIG. 3 and shows how the spaces 10.11 and 10.12 formed by the cooling liquid inlet grooves 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 form a shunt between the sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 in combination with the inside surface 2.5 of the nozzle cap 2 Prevent the coolant flow and coolant return. At the same time, a shunt between the spaces 10.11 and 10.12 is prevented by the section 4.43 of the protruding area 4.33. Thus, in each position of the nozzle 4 to the nozzle cap 2 to each other, the shunt of the cooling liquid is prevented, the sheet dimensions d4 and e4 of sections 4.41 and 4.42 of the nozzle 4 must be at least as large as the radians b2 to the nozzle facing recesses 2.6 of the nozzle cap 2 (s , Fig. 14 to 16 ).

FIG. 3b is a sectional view taken along the line BB of the plasma torch FIG. 3 showing the plane of the deflection space 10.10 and the connection with both coolant outlets 4.20 and 4.21 through the groove 5.1 in the nozzle holder 5.

Fig. 4 shows the nozzle 4 of the plasma burner head FIG. 3 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 extend over a portion of the first section 4.1 and the second section 4.2 in the outer surface of the nozzle 4 4.5 to the nozzle tip 4.11 and end in front of the cylindrical outer surface 4.3. The Kühlflüssigkeitsrücklaufnut 4.22 extends over the second section 4.2 of the nozzle 4. The width alpha 4 of the Kühlflüssigkeitsrücklaufnut 4.22 in the circumferential direction is about 190 °. Between the Kühlflüssigkeitszulaufnuten 4.20; 4.21 and the coolant return groove 4.22 are the outwardly projecting areas 4.31; 4.32 and 4.33 with the corresponding sections 4.41; 4.42 and 4.43.

FIG. 5 shows a plasma burner similar FIG. 3 but according to another particular embodiment. The nozzle 4 has two Kühlflüssigkeitszulaufnuten 4.20 and 4.21 (s. Fig. 5a ). Again, the cooling liquid is directed almost perpendicular to the longitudinal axis of the plasma burner head 1 of the nozzle holder 5 on the nozzle 4 in the cooling liquid space 10. For this purpose, in the deflection space 10.10 of the cooling liquid space 10, the cooling liquid is deflected from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma burner in the direction of the first nozzle section 4.1 almost perpendicular to the longitudinal axis of the plasma burner head 1. Then, the cooling liquid flows through a groove 4.6 of the nozzle 4 in the two by the Kühlflüssigkeitsvorlaufnuten 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 spaces formed 10.11 and 10.12 to the nozzle bore 4.10 surrounding area 10.20 of the cooling liquid space 10 and flows around the nozzle 4 there , Thereafter, the cooling liquid flows back through the space 10.15 formed by the cooling liquid return groove 4.22 of the nozzle 4 and the nozzle cap 2 to the coolant return WR, the transition taking place substantially parallel to the longitudinal axis of the plasma burner head.

Fig. 5a is the sectional view taken along the line AA of the plasma torch FIG. 5 showing how the spaces 10.11 and 10.12 formed by the cooling liquid supply grooves 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 have a shunt through the sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 in combination with the inside surface 2.5 of the nozzle cap 2 between the coolant flow and coolant return. At the same time, a shunt between the spaces 10.11 and 10.12 is prevented by the section 4.43 of the protruding area 4.33. So that in each position of the nozzle 4 to the nozzle cap 2 to each other, the shunt of the cooling liquid is prevented, the sheet dimensions d4 and e4 of sections 4.41 and 4.42 of the nozzle 4 must be at least as large as the radians b2 to the nozzle facing recesses 2.6 of the nozzle cap. 2

FIG. 5b is a sectional view taken along the line BB of the plasma torch FIG. 5 which shows the plane of the deflection 10.10 and the connection with both Kühlflüssigkeitszuläufen through the groove 4.6 in the nozzle 4.

Fig. 6 shows the nozzle 4 of the plasma burner head FIG. 5 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 extend over a portion of the first section 4.1 and the second section 4.2 in the outer surface of the nozzle 4 4.5 to the nozzle tip 4.11 and end in front of the cylindrical outer surface 4.3. The Kühlflüssigkeitsrücklaufnut 4.22 extends over the second section 4.2 of the nozzle 4. The width alpha 4 of the Kühlflüssigkeitsrücklaufnut 4.22 in the circumferential direction is about 190 °. Between the cooling liquid grooves 4.20; 4.21 and the Kühlflüssigkeitsrücklaufnut 4.22 are the outwardly projecting areas 4.31; 4.32 and 4.33 with the corresponding sections 4.41; 4.42 and 4.43. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 are interconnected by the groove 4.6 of the nozzle.

FIG. 7 FIG. 2 illustrates a plasma burner head according to a further specific embodiment of the invention. Here, too, the cooling liquid is directed into a coolant liquid space 10, approximately perpendicular to the longitudinal axis of the plasma burner head 1, from a nozzle holder 5 onto the nozzle 4. For this purpose, in the deflection space 10.10 of the cooling liquid space 10, the cooling liquid is deflected from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma burner in the direction of the first nozzle section 4.1 almost perpendicular to the longitudinal axis of the plasma burner head 1. Thereafter, the cooling liquid flows through a space 10.11 formed by a cooling liquid supply groove 4.20 of the nozzle 4 and the nozzle cap 2 (see FIG. Fig. 7a ) in the area surrounding the nozzle bore 4.10 10.20 of the cooling liquid chamber 10 and flows around the nozzle 4 there. Thereafter, the cooling liquid flows through a space 10.15 formed by a Kühlflüssigkeitsrücklaufnut 4.22 of the nozzle 4 and the nozzle cap 2 back to the coolant return WR, wherein the transition takes place here almost perpendicular to the longitudinal axis of the plasma burner head, through a deflection 10.10.

Fig. 7a is a sectional view taken along the line AA of the plasma torch FIG. 7 showing how the space 10.11 formed by the coolant inlet groove 4.20 of the nozzle 4 and the nozzle cap 2 through the sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 in combination with the inside surface of the nozzle cap 2 shunts between the coolant flow and the coolant return prevent.

FIG. 7b is a sectional view taken along the line BB of the plasma burner head FIG. 7 showing the plane of the deflection spaces 10.10.

Fig. 8 shows the nozzle 4 of the plasma burner head FIG. 7 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnut 4.20 and the Kühlflüssigkeitsrücklaufnut 4.22 extend over a portion of the first section 4.1 and the second section 4.2 in the outer surface 4.5 of the nozzle 4 to the nozzle tip 4.11 and end in front of the cylindrical outer surface 4.3. The center of the Kühlflüssigkeitszulaufnut 4.20 and the center of the Kühlflüssigkeitsrücklaufnut 4.22 are offset by 180 ° to each other over the circumference of the nozzle 4 and the same size. Between the Kühlflüssigkeitsvorlaufnut 4.20 and the Kühlflüssigkeitsrücklaufnut 4.22 are the outwardly projecting areas 4.31 and 4.32 with the corresponding sections 4.41 and 4.42.

The FIG. 9 shows a plasma burner head according to another specific embodiment of the invention. The nozzle 4 has two Kühlflüssigkeitsvorlaufnuten 4.20 and 4.21. Again, the cooling liquid is almost perpendicular to the longitudinal axis of the plasma burner head 1 of the nozzle holder 5 on the nozzle 4 aptly in the Coolant space 10 passed. For this purpose, in a deflection space 10.10 of the cooling liquid space 10, the cooling liquid is deflected from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma torch in the direction of the first nozzle section 4.1 almost perpendicular to the longitudinal axis of the plasma burner head 1. Then, the cooling liquid flows through a groove 5.1 of the nozzle holder 5 in the two formed by the Kühlflüssigkeitszulaufnuten 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 spaces 10.11 and 10.12 to the nozzle bore 4.10 surrounding area 10.20 of the cooling liquid space 10 and flows around the nozzle 4 there , Thereafter, the cooling liquid flows back through the space formed by the Kühlflüssigkeitsrücklaufnut 4.22 of the nozzle 4 and the nozzle cap 2 10.15 back to the coolant return WR, the transition here is almost perpendicular to the longitudinal axis of the plasma burner head, by a deflection 10.10.

Fig. 9a is a sectional view taken along the line AA of the plasma torch FIG. 9 showing how the spaces 10.11 and 10.12 formed by the cooling liquid inlet grooves 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 pass through the sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 in combination with the inner surface of the nozzle cap 2 Prevent the coolant flow and coolant return. At the same time, a shunt between the spaces 10.11 and 10.12 is prevented by the section 4.43 of the protruding area 4.33.

FIG. 9b is a sectional view taken along the line BB of the plasma burner head FIG. 9 showing the plane of the deflection spaces 10.10 and shows the connection with both Kühlflüssigkeitsvorläufen 4.20 and 4.21 through the groove 5.1 in the nozzle holder 5.

FIG. 10 shows the nozzle 4 of the plasma burner head FIG. 9 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 extend over a portion of the first section 4.1 and the second section 4.2 in the outer surface 4.5 of the nozzle 4 to the nozzle tip 4.11 and end in front of the cylindrical outer surface 4.3. The Kühlflüssigkeitsrücklaufnut 4.22 extends over the second section 4.2 and the first section 4.1 in the outer surface 4.5 of the nozzle 4. Between the Kühlflüssigkeitsvorlaufnuten 4.20; 4.21 and the Kühlflüssigkeitsrücklaufnut 4.22 are the outwardly projecting areas 4.31; 4.32 and 4.33 with the corresponding sections 4.41; 4.42 and 4.43.

FIG. 11 shows a plasma burner head similar FIG. 5 but according to another particular embodiment of the invention. The bores of the coolant flow WV and the coolant return are arranged at an angle of 90 °. The nozzle 4 has two Kühlflüssigkeitszulaufnuten 4.20 and 4.21 and in the circumferential direction of the first section 4.1 extending over the entire circumference and the Kühlflüssigkeitszulaufnuten connecting groove 4.6. The cooling liquid is directed approximately perpendicular to the longitudinal axis of the plasma burner head 1 of the nozzle holder 5 on the nozzle 4 aptly into the cooling liquid space 10. For this purpose, in the deflection space 10.10 of the cooling liquid space 10, the cooling liquid is deflected from the direction parallel to the longitudinal axis in the bore of the cooling liquid flow WV of the plasma burner in the direction of the first nozzle section 4.1 almost perpendicular to the longitudinal axis of the plasma burner head 1. Then, the cooling liquid flows through the groove 4.6, which extends in the circumferential direction of the first section 4.1 of the nozzle 4 on a partial circumference between the grooves 4.20 and 4.21, ie over about 300 °, in the two by the Kühlflüssigkeitsvorlaufnuten 4.20 and 4.21 of the Nozzle 4 and the nozzle cap 2 formed spaces 10.11 and 10.12 to the nozzle bore 4.10 surrounding area 10.20 of the cooling liquid space 10 and flows around the nozzle 4 there. Thereafter, the cooling liquid flows back through the space 10.15 formed by the cooling liquid return groove 4.22 of the nozzle 4 and the nozzle cap 2 to the coolant return WR, the transition taking place substantially parallel to the longitudinal axis of the plasma burner head.

Fig. 11a is a sectional view taken along the line AA of the plasma torch FIG. 11 showing how the spaces 10.11 and 10.12 formed by the cooling liquid inlet grooves 4.20 and 4.21 of the nozzle 4 and the nozzle cap 2 form a shunt through the sections 4.41 and 4.42 of the protruding areas 4.31 and 4.32 of the nozzle 4 in combination with the inside surface 2.5 of the nozzle cap 2 between the coolant flow and coolant return. At the same time, a shunt between the spaces 10.11 and 10.12 is prevented by the section 4.43 of the protruding area 4.33. So that in each position of the nozzle 4 to the nozzle cap 2 to each other, the shunt of the cooling liquid is prevented, the sheet dimensions d4 and e4 of sections 4.41 and 4.42 of the nozzle 4 must be at least as large as the radians b2 to the nozzle facing recesses 2.6 of the nozzle cap. 2

FIG. 11b is a sectional view taken along the line BB of the plasma torch FIG. 11 , Which shows the plane of the deflection 10.10 and the connection with both cooling liquid flows through the over approximately 300 ° circumferential groove 4.6 in the nozzle 4 and offset by 90 ° arranged holes for the coolant flow WV and the coolant return WR.

FIG. 12 shows the nozzle 4 of the plasma burner head FIG. 11 , It has a nozzle bore 4.10 for the exit of a plasma jet at a nozzle tip 4.11, a first section 4.1, the outer surface 4.4 is substantially cylindrical, and adjoining the nozzle tip 4.11 second section 4.2, the outer surface of the 4.5 to the nozzle tip 4.11 out in essentially conically tapered. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 extend over a portion of the first section 4.1 and the second section 4.2 in the outer surface of the nozzle 4 4.5 to the nozzle tip 4.11 and end in front of the cylindrical outer surface 4.3. The Kühlflüssigkeitsrücklaufnut 4.22 extends over the second section 4.2 of the nozzle 4. Between the Kühlflüssigkeitszulaufnuten 4.20; 4.21 and the Kühlflüssigkeitsrücklaufnut 4.22 are the outwardly projecting areas 4.31; 4.32 and 4.33 with the corresponding sections 4.41; 4.42 and 4.43. The Kühlflüssigkeitszulaufnuten 4.20 and 4.21 are by a circumferential direction of the first section 4.1 of the nozzle 4 on a Partial circumference between the grooves 4.20 and 4.21, ie over about 300 ° extending groove 4.6 of the nozzle connected together. This is particularly advantageous for the cooling of the transition between the nozzle holder 5 and the nozzle 4.

FIG. 13 shows a nozzle according to another specific embodiment of the invention, which in the plasma burner head after FIG. 8 can be used. The Kühlflüssigkeitszulaufnut 4.20 is connected to a groove 4.6 which extends in the circumferential direction over the entire circumference. This has the advantage that the bore for the cooling liquid flow WV and the coolant return WR in the plasma burner head need not be arranged offset by exactly 180 °, but also as for example in FIG. 11 can be arranged offset by 90 °. In addition, this is advantageous for the cooling of the transition between the nozzle holder 5 and the nozzle 4. The same can of course be used for a Kühlflüssigkeitsrücklaufnut 4.22.

FIG. 14 shows a nozzle cap 2 according to a particular embodiment of the invention. The nozzle cap 2 has an essentially conically tapering inner surface 2.2, which in this case has recesses 2.6 in a radial plane. The recesses 2.6 are arranged equidistantly over the inner circumference and semicircular in the radial section.

The in the FIGS. 15 and 16 shown nozzle caps according to further particular embodiments of the invention differ from the in Fig. 14 shown embodiment in the shape of the recesses 2.6. The recesses 2.6 in Fig. 15 are in the view shown there to the nozzle tip out frustoconical, with in Fig. 16 the frustoconical shape is slightly rounded.

The features of the invention disclosed in the present description, in the drawings and in the claims will be essential in both individually and in any combination for the realization of the invention in its various embodiments.

Claims (15)

A nozzle (4) for a liquid cooled plasma torch comprising a nozzle bore (4.10) for exit of a jet of plasma at a nozzle tip (4.11), a first portion (4.1) whose outer surface (4.4) is substantially cylindrical and adjoins the nozzle tip (4.11) subsequent second section (4.2) whose outer surface (4.5) tapers towards the nozzle tip (4.11) substantially conically, wherein a) at least one Flüssigkeitszulaufnut (4.20, 4.21) is provided and over a portion of the first section (4.1 ) and over the second section (4.2) in the outer surface (4.5) of the nozzle (4) to the nozzle tip (4.11) and precisely one liquid return groove (4.22) separate from the liquid inlet groove (s) (4.20; 4.21) and extends over the second section (4.2), or b) exactly one liquid inlet groove (4.20 or 4.21) is provided and extends over a portion of the first section (4.1) and extending over the second portion (4.2) in the outer surface (4.5) of the nozzle (4) to the nozzle tip (4.11) and providing at least one liquid return groove (4.22) separate from the liquid inlet groove (4.20 or 4.21) and extending over the second portion (4.2). Nozzle according to claim 1, characterized in that the liquid return groove (s) (4.22) also extend / extend over part of the first section (4.1) in the outer surface of the nozzle (4). Nozzle according to claim 1 or 2, characterized in that in case a) at least two liquid inlet grooves (4.20; 4.21) and in case b) at least two liquid return grooves (4.22) are provided. Nozzle according to claim 3, characterized in that the center of the liquid inlet groove (4.20) and the center of the liquid return groove (4.22) are offset by 180 ° relative to each other over the circumference of the nozzle (4). Nozzle according to one of claims 1 to 4, characterized in that in case a) the width of the liquid return groove and in case b) the width of the liquid inlet groove in the circumferential direction is in the range of 90 ° to 270 °. Nozzle according to one of the preceding claims, characterized in that in case a) in the first section (4.1) of the nozzle (4) there is a groove (4.6) communicating with the liquid inlet groove (4.20) and in that case b) in the first section (4.1) of the nozzle (4) is a groove which is in communication with the liquid return groove (4.22), in particular that in case a) the groove (4.6) in the circumferential direction of the first section (4.1) Extends in the case of a) the groove (4.6) in the circumferential direction of the first portion (4.1) of the nozzle (4) over an angle in the range of 60 ° to 300 ° and that in Case b) the groove extends in the circumferential direction of the first section (4.1) of the nozzle (4) over an angle in the range of 60 ° to 300 ° or in the case a) the groove (4.6) in the circumferential direction of the first section (4.1) the nozzle (4) extends over an angle in the range of 90 ° to 270 ° and that in case b) the groove extends in the circumferential direction of the first section (4.1) of the nozzle (4) over an angle in the range of 90 ° to 270 °. Nozzle according to one of the preceding claims, characterized in that exactly two liquid return grooves (4.20; 4.21) are provided in case a) and exactly two liquid return grooves (4.22) are provided in case b). Nozzle according to claim 7, characterized in that in case a) the two liquid inlet grooves (4.20; 4.21) are arranged circumferentially of the nozzle symmetrical to a straight line extending from the center of the liquid return groove (4.22) at right angles through the longitudinal axis of the nozzle (4), and in case b) the two liquid return grooves are arranged circumferentially around the nozzle symmetrically to a straight line extending from the center of the liquid inlet groove at right angles through the longitudinal axis of the nozzle (4). Nozzle according to claim 7 or 8, characterized in that in case a) the centers of the two liquid inlet grooves (4.20; 4.21) and in case b) the centers of the two liquid return grooves are offset by an angle to each other over the circumference of the nozzle (4) which is in the range of 30 ° to 180 °. Nozzle according to one of claims 7 to 9, characterized in that in case a) the width of the liquid return groove (4.22) and in case b) the width of the liquid inlet groove in the circumferential direction is in the range of 120 ° to 270 °. Nozzle according to one of Claims 7 to 10, characterized in that, in case a), the two liquid inlet grooves (4.20; 4.21) in the first section (4.1) of the nozzle (4) communicate with each other and in case b) the two liquid return grooves in first section (4.1) of the nozzle (4) communicate with each other. Nozzle according to Claim 11, characterized in that, in case a), the two liquid inlet grooves (4.20; 4.21) in the first section (4.1) of the nozzle (4) communicate with each other through a groove (4.6) and in case b) the two Liquid return grooves in the first section (4.1) of the nozzle (4) are connected by a groove, in particular that the groove (4.6) in case a) beyond one or both Flüssigkeitszulaufnuten (4.20, 4.21) and that in case b) the groove beyond one or both of the liquid return grooves. A plasma burner head (1) comprising: a nozzle according to any one of claims 1 to 12, - A nozzle holder (5) for holding the nozzle (4), and - A nozzle cap (2), wherein the nozzle cap (2) and the nozzle (4) form a cooling liquid space (10) via two each offset by 60 ° to 180 ° holes with a cooling liquid supply line or Coolant return line is connectable, wherein the nozzle holder (5) is designed so that the cooling liquid almost perpendicular to the longitudinal axis of the plasma burner head (1) on the nozzle (4) aptly into the cooling liquid space (10) and / or almost perpendicular to the longitudinal axis of the cooling liquid space in the nozzle holder arrives. Plasma burner head (1) according to claim 13, characterized in that the nozzle (4) has one or two Kühlflüssigkeitszulaufnut (s) (4.20; 4.21), and the nozzle cap (2) on its inner surface (2.5) at least two, in particular exactly three, Recesses (2.6), whose openings facing the nozzle (4) each extend over a radian measure (b ₂ ), wherein the radian measure (d ₄ , e ₄ ) of the circumferential to the Kühlflüssigkeitszulaufnut (s) (4.20, 4.21) adjacent, with respect to the or the Kühlflüssigkeitszulaufnut (s) outwardly projecting portions (4.31, 4.32) of the nozzle (4) in each case at least as large as the radians (b ₂ ). Plasma burner head (1) according to claims 13 or 14, characterized in that the radian measure (c2) of the portion between the recesses (2.6) of the nozzle cap (2) is at most half as large as the minimum radian dimension (a4) of the Kühlflüssigkeitsrücklaufnut (4.22) or the minimum amount of bends (b4) of the coolant inlet groove (s) (4.20) and / or (4.21) of the nozzle (4).

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