EP3054749A1 - Nozzle for a plasma arc torch - Google Patents

Abstract

Nozzles for a liquid-cooled plasma arc torch head, and arrangement of a nozzle holder and nozzle and plasma arc torch head and plasma arc torch with the same / same.

Description

The present invention relates to nozzles for a liquid-cooled plasma arc torch head, an assembly of a nozzle holder and nozzle for a liquid-cooled plasma arc torch head, a plasma arc torch head, and a plasma arc torch with the same.

From the DE 10 2009 006 132 B4 For example, a nozzle for a liquid-cooled plasma arc torch is known which has a body having an axial overall length, an inner surface and an outer surface, a front and a rear end and a nozzle opening at the front end. The known nozzle has from the rear (from the rear end) first a receiving portion for receiving the same in a nozzle holder and then a groove in which a circular ring can be arranged or arranged on. In certain cases, this may have the disadvantage that, when the nozzle is installed in a plasma burner head, the space for the cooling liquid, in particular cooling water, towards the nozzle holder and thus the contact area between the cooling liquid and the nozzle is limited to the rear.

There are also known nozzles in which a groove with an arranged therein or arranged round ring is located directly at the rear end thereof. This in turn has the Disadvantage that the round ring when inserting into a nozzle holder for inserting the nozzle can be damaged in the nozzle holder, for example, if in the nozzle holder, for example, elements such as projections, as shown in the DE 10 2007 005 316 B4 is described, for defined guidance of the nozzle are present.

The present invention is therefore based on the object to design the known nozzle such that damage to the circular ring when inserting a nozzle is avoided in a nozzle holder, but at least reduced and at the same time a larger area that can come into contact with coolant, is provided ,

According to the invention, this object is achieved according to a first aspect by a nozzle for a liquid-cooled plasma arc torch head, comprising a body having an axial total length L, an inner surface and an outer surface, a front and a rear end and a nozzle opening at the front end, wherein the outer surface of the body , starting from the rear end, a substantially cylindrical first portion having an axial length L1, in which at the rear end of the body has a preferably circumferentially extending groove for or with a circular ring disposed therein, to the rear end of the body is limited a projection which defines an outer diameter D11 of the body, and located at the front end a centering surface for a nozzle holder which defines an outer diameter D12 of the body, and an adjoining the front end second portion with an axial Length L2, which has an axial abutment surface for a nozzle holder at the boundary to the first portion, which defines an outer diameter D21 of the body, and tapers substantially conically, at least in a portion to the front end of the body, wherein D12 - D11 ≥ 1 , 5mm and / or (D12 - D11) / D12≥0.07.

A conically or conically tapering section is intended to mean in particular a section in which, when connecting the rearmost point (edge) of the section to the foremost point (edge) of the section, the line parallel to the longitudinal axis of the nozzle or with a minimum Deviation of more than ± 15 °.

• Der Außendurchmesser, den ein virtueller Kreis mit dem Radius der in einer senkrecht zur Längsachse der Düse gebildeten Ebene zwischen dem Schnittpunkt der Ebene und der Längsachse und dem größten Abstand zur Außenfläche der Düse bilden würde.
• Es besteht die Möglichkeit, dass in der Ebene eine vollständiger Kreis durch die Außenbegrenzung der Düse gebildet wird, aber auch die Möglichkeit, dass nur ein Teilbereich oder nur einzelne Abschnitte vorhanden sind und der Kreis und auch der Durchmesser nur virtuell bestehen.
• Es können in der Oberfläche der Düse Nuten oder andere Vertiefungen oder Unterbrechungen vorgesehen sein.

Furthermore, the following should in particular be meant with an outer diameter:

• The outer diameter that a virtual circle would make with the radius of the plane formed in a plane perpendicular to the longitudinal axis of the nozzle between the intersection of the plane and the longitudinal axis and the greatest distance to the outer surface of the nozzle.
• There is the possibility that in the plane a complete circle is formed by the outer boundary of the nozzle, but also the possibility that only a partial area or only individual sections are present and the circle and the diameter exist only virtually.
• It may be provided in the surface of the nozzle grooves or other recesses or interruptions.

According to a further aspect, this object is achieved by a nozzle for a liquid-cooled plasma arc torch comprising a body having an overall axial length L, an inner surface and an outer surface, a front and a rear end and a nozzle opening at the front end, wherein the outer surface of the body, starting from the rear end, a substantially cylindrical first portion having an axial length L1, in which at the rear end of the body has a preferably circumferentially extending groove for or with a circular ring disposed therein, to the rear end of the body by a Is limited projection defining an outer diameter D11 of the body, and located at the front end a centering surface for a nozzle holder which defines an outer diameter D12 of the body, and having a subsequent thereto to the front end second portion with an axial length L2, which has an axial abutment surface for a nozzle holder at the boundary to the first section, which defines an outer diameter D21 of the body, and tapers substantially conically, at least in a section to the front end of the body, in particular according to claim 1, wherein for the length L12 of Distance between the axial abutment surface of the second portion and the nearest edge line of the groove and the length L13 of the distance between said edge line and the rear end of the body is L12 / L13≥3, preferably ≥3.3 and / or wherein for Length L12 of the distance between the axial abutment surface of the second section and the nearest edge line of the groove and the length L of the first section is L12 / L1≥0.75 and more preferably L12 / L1≥0.77, and / or where D12 / L1≤2,3.

According to a further aspect, this object is achieved by an arrangement of a nozzle holder and a nozzle according to one of claims 1 to 16.

Finally, this object is also achieved by a liquid-cooled plasma arc burner head, comprising a nozzle according to one of claims 1 to 16 or an arrangement according to one of claims 17 to 19.

The nozzles may be provided that the outer diameter D12 is the largest outer diameter of the first portion.

Furthermore, it can be provided that the outer diameter D21 is the largest outer diameter of the second section.

Advantageously, the largest outer diameter of the first portion is smaller than the largest outer diameter of the second portion.

Conveniently located in the outer surface of the first portion at least one further groove.

In particular, it may be provided that the at least one further groove has a cross-sectional area of at least 3 mm ² . The term "cross-sectional area" is intended to mean the area perpendicular to the longitudinal extent of the groove.

In addition, the further groove advantageously extends in the circumferential direction of the body.

In particular, it may be provided that the further groove extends in the circumferential direction of the body over an angle in the range of about 20 ° to about 360 °.

According to a particular embodiment, the further groove is limited towards the front end of the body by a circumferentially extending body of the front projection whose outer surface is formed by the centering surface, and / or the further groove 2.11 toward the rear end of the body by is formed in the circumferential direction of the body extending rear projection is limited.

In particular, it can be provided that the front projection defines an outer diameter or a local largest outer diameter of the body and the rear projection defines an outer diameter or a local largest outer diameter, wherein the outer diameter or local largest outer diameter of the front and rear projections are equal to or differ by a maximum of about 0.2mm from each other.

According to another particular embodiment of the present invention, at least one groove and / or bore and / or recess and / or other aperture and / or channel is / are in fluid communication with the first portion of the outer surface in the second portion of the outer surface is / are.

Advantageously located / located in the second portion of the outer surface at least one groove and / or bore and / or recess and / or other opening and / or a channel located / / which is in fluid communication with the further groove in the first portion of the outer surface /stand.

Conveniently located on the outer surface of the body between the groove for a circular ring or with a round ring arranged therein and the further groove a circumferential receiving area for connection to a nozzle holder.

Alternatively it can be provided that there is a circumferential receiving area for connection to a nozzle holder on the outer surface of the body between the groove for a circular ring or with a round ring arranged therein and the further groove.

Expediently, the receiving region has at least one radial projection and / or at least one radial depression. The radial projections and / or Recesses can extend over only a limited angle in the circumferential direction and / or be arranged equidistantly.

According to a particular embodiment of the arrangement, the nozzle holder has on its connecting side a cylinder wall with an end face abutting against the axial abutment surface of the nozzle and with an inner surface which abuts against the centering surface of the nozzle, preferably with little or no play.

Advantageously, the nozzle holder on the inner surface of the cylinder wall on a receiving region of the nozzle complementary receiving area.

Finally, the present invention provides both a liquid-cooled plasma arc torch head and a liquid-cooled plasma arc torch, each comprising a nozzle according to any one of claims 1 to 16 or an arrangement according to any one of claims 17 to 19.

The invention is based on the surprising finding that the special design of the outer surface of the nozzle, the groove with the round ring can be arranged as far as possible at the rear end of the nozzle without the round ring is damaged, and at the same time a larger area, the can come into contact with the cooling liquid is provided. In addition, the centering of the nozzle in the nozzle holder is further improved.

For example, as long as possible a first portion of the body of the nozzle allows a good cooling of the transition point between a nozzle holder and the nozzle and a good centering of the nozzle in the nozzle holder. Good cooling of the interface is necessary when igniting the pilot arc that burns between the electrode and the nozzle of a plasma arc torch. It is also necessary if the plasma arc burner is operated indirectly. In the latter case, the plasma arc often burns with high electric power or several kW between the electrode and the nozzle. Currents above 100 A can flow.

• Figur 1 eine Schnittansicht (links) und eine Rückansicht (rechts) von einer Düse gemäß einer ersten besonderen Ausführungsform der vorliegenden Erfindung;
• Figur 2 eine Schnittansicht (links) und eine Rückansicht (rechts) von einer Düse gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung;
• Figur 3 eine Schnittansicht (links) und eine Rückansicht (rechts) von einer Düse gemäß einer weiteren besonderen Ausführungsform der vorliegenden Erfindung;
• Figur 4 eine Schnittansicht eines Plasmalichtbogenbrennerkopfes mit der Düse von Figur 1.
• Figur 5 eine Schnittansicht eines Plasmalichtbogenbrennerkopfes mit der Düse von Figur 2.
• Figur 6 eine Schnittansicht eines Plasmalichtbogenbrennerkopfes mit der Düse von Figur 3.

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

• FIG. 1 a sectional view (left) and a rear view (right) of a nozzle according to a first particular embodiment of the present invention;
• FIG. 2 a sectional view (left) and a rear view (right) of a nozzle according to another particular embodiment of the present invention;
• FIG. 3 a sectional view (left) and a rear view (right) of a nozzle according to another particular embodiment of the present invention;
• FIG. 4 a sectional view of a plasma arc burner head with the nozzle of FIG. 1 ,
• FIG. 5 a sectional view of a plasma arc burner head with the nozzle of FIG. 2 ,
• FIG. 6 a sectional view of a plasma arc burner head with the nozzle of FIG. 3 ,

The respective enlarged drawing excerpts in the FIGS. 4 to 6 show details of the arrangement of the nozzle and a nozzle holder.

The in the FIG. 1 The nozzle for a liquid-cooled plasma arc torch shown comprises a body 2 with an overall axial length L, ie along the longitudinal axis M1, an inner surface 2.20 and an outer surface 2.22, a front end 2.24 and a rear end 2.26 and a nozzle opening 2.28 at the front end 2.24. In addition, the body 2 has a groove 2.38 at its front end 2.24. In the groove 2.38, when the nozzle is installed in the plasma arc burner, there is a round ring 2.40 (see FIG. 4 and 5 ) for sealing the space between nozzle and nozzle cap 3 (see FIG. 4 and 5 ). The outer surface 2.22 of the body 2 has, starting from the rear end 2.26, a substantially cylindrical first section 2.1 with an axial length L1, in which at the rear end of the body 2 2.26 of a circumferentially extending groove 2.10 for a circular ring ( not shown) delimited to the rear end 2.26 of the body 2 by a projection 2.30 defining an outer diameter D1 of the body 2, and at the front end 2.24 is a centering surface A11 for a nozzle holder (not shown) which defines an outer diameter D12 of the body 2. Furthermore, the outer surface has a second section 2.2 with an axial length L2 adjoining the first section 2.1 towards the front end 2.24 and having an axial stop face B 11 for a nozzle holder (not shown) at the boundary to the first section 2.1, which defines an outer diameter D21 of the body 2, and tapers substantially conically at least in a partial section towards the front end 2.24 of the body. The first section 2.1 of the outer surface 2.22 thus has between the boundary between the first section 2.1 and the second section 2.2 and the groove 2.10 a particular large outer surface A13, which, when the nozzle is installed in a plasma arc burner head (not shown) with a Coolant can come into contact, whereby the cooling is improved.

Since the diameter D12 in this embodiment is 22.8 mm and the diameter D11 in this embodiment is 20.8 mm, the difference D12-D11 = 2 mm. In addition, results for (D12-D11) / (D12) -0.088.

From the FIG. 1 it also follows that the outer diameter D12 is the largest outer diameter of the first section 2.1 and the outer diameter D21 is the largest outer diameter of the second section 2.2, wherein the largest outer diameter D 12 of the first section 2.1 is smaller than the largest outer diameter D21 of the second section 2.2 , In addition, the outer diameter of the body 2 in FIG. 1 on the left (D11) and on the right (D12a) of the groove 2.10, ie D11 = D12a.

In addition, in the second section 2.2 of the outer surface 2.22, a channel B 13 is in fluid communication with the first section 2.1 of the outer surface 2.22. The channel B13 may also extend at least partially in the first section 2.1.

With L12-8.2mm, L13 = 2.3mm and L1 = 10.5m, L12 / L13 = 8.2mm / 2.3mm = 3.565 and L12 / L1 = 0.781 and D12 / L1 = 2.171.

FIG. 2 shows a nozzle for a liquid-cooled plasma arc burner head (not shown), a body 2 with an axial total length L, an inner surface 2.20 and an outer surface 2.22, a front end 2.24 and a rear end 2.26 and a nozzle opening 2.28 at the front end 2.24 includes. In addition, the body 2 has a groove 2.38 at its front end 2.24. In the groove 2.38, when the nozzle is installed in the plasma arc burner, there is a round ring 2.40 (see FIG. 4 and 5 ) for sealing the space between nozzle and nozzle cap 3 (see FIG. 4 and 5 ). The outer surface 2.22 of the body 2 has, starting from the rear end 2.26, a substantially cylindrical first section 2.1 with an axial length L1, in which at the rear end of the body 2 2.26 of a circumferentially extending groove 2.10 for a circular ring ( not shown) which is bounded to the rear end 2.26 of the body by a projection 2.30 defining an outer diameter D11 of the body 2, and at the front end 2.24 a centering surface A11 for a nozzle holder (not shown) having an outer diameter D12 of the body Are defined. In addition, the outer surface 2.22 has a second section 2.2, which adjoins the front end 2.24, and has an axial length L2 which defines an axial stop surface B 11 for a nozzle holder at the boundary to the first section 2.1, which defines an outer diameter D21 of the body 2 , and at least in a partial section tapers substantially conically towards the front end 2.24 of the body 2. With regard to the dimensions D12 and D11, the same values and ratios apply with respect to those in the FIG. 1 shown nozzle. In the outer surface 2.22 of the first section 2.1, however, there is another groove 2.11. This preferably has a cross-sectional area of at least 3 mm ² . In addition, it extends advantageously in the circumferential direction of the body 2. The further groove 2.11 is in the direction of the front end of 2.24 of the body 2 by a circumferentially extending body 2 of the front projection 2.34, whose outer surface is formed by the centering surface A11, limited and Direction of the rear end of the body 2 2.26 limited by a running in the circumferential direction of the body 2 rear projection 2.36, whose outer surface is formed by the surface or centering surface A12. For those in the FIG. 2 The same values apply to the nozzle shown as for L12 / L13, L12 / L1 and D12 / L1.

As further from the FIG. 2 2, the front projection 2.34 defines a local largest outer diameter D12 of the body 2 and the rear projection 2.36 defines one local largest outer diameter D12. In other words, in this example, the local largest outer diameters of the front and rear protrusions 2.34 and 2.36 are the same. The local largest outer diameters of the front and rear projections need not be the same size. As a rule, however, the rear projection 2.36 should not be larger than the front projection 2.34. Through the front and rear projections 2.34 and 2.36 of identical outside diameter D12, there are two contact surfaces in this nozzle which are in contact with a nozzle holder (not shown) when the nozzle is installed. It is the centering surface A11 and the surface or centering surface A12.

As also from the FIG. 2 shows, the second section 2.2 has a groove B 12 which is in fluid communication with the further groove 2.11. The groove B 12 may also extend at least partially in the first section 2.1.

FIG. 3 shows a nozzle for a liquid-cooled plasma arc torch with a body 2 having an axial total length L, that is along the longitudinal axis M1, an inner surface 2.20 and an outer surface 2.22, a front end 2.24 and a rear end 2.26 and a nozzle opening 2.28 at the front end 2.24 having. The outer surface 2.22 of the body 2 has, starting from the rear end 2.26, a first section 2.1 having the same features as the first section 2.1 of FIG FIG. 2 shown nozzle and a to the first section 2.1 to the front end 2.24 out directly adjacent second section 2.2 with an axial length L2. The second section 2.2, in particular the front end 2.24 is designed differently by way of example. The body 2 has at the front end 2.24 in contrast to the body of FIG. 2 no groove 2.38. The nozzle built into a plasma arc burner head FIG. 3 is in FIG. 6 shown. Here, the sealing of the space between the nozzle and nozzle cap 3 by touching the metallic surfaces of the nozzle and the nozzle cap 3. Furthermore, another inner contour of the nozzle or the body is shown by way of example. This nozzle can be used, for example, for indirect operation.

FIG. 4 shows a liquid-cooled plasma arc burner head with the nozzle of FIG. 1 , The body 2 of the nozzle is fixed in a nozzle holder 7 and is replaced by a Nozzle cap 3 fixed. In the inner cavity of the body 2, an electrode 1 is arranged. Between the electrode 1 and the body 2 there is a plasma gas guide 4 for plasma gas PG, which flows through the plasma gas guide 4, then through the space between the electrode 1 and the nozzle and finally from the nozzle opening 2.28. The plasma arc burner head further has a nozzle cap 5 which is held by a nozzle cap holder 8. Between the nozzle cap 3 and the nozzle cap 5, a secondary gas guide 6 is arranged for secondary gas SG. The secondary gas SG flows through openings (not shown) of the secondary gas guide 6, then through the space between the nozzle cap 3 and nozzle cap 5 and ultimately from the front opening 5.1 of the nozzle cap 5. There is also the possibility that the nozzle and nozzle cap 3 from a part consist. There are also plasma arc burner heads, which are operated without secondary gas. These then usually have no nozzle cap, No Düsenschutzkappenhalterung and no secondary gas guide.

The cooling liquid flows through the nozzle holder 7 via the coolant flow WV, flows through the space 10 between nozzle holder 7 and nozzle, then flows through the channels B 13 of the nozzle into the space between nozzle and nozzle cap 3 before flowing back through the coolant return WR.

The first section 2.1 of the body 2 is inserted into the nozzle holder 7. In this case, an axial abutment surface B11 of the body 2 strikes an axial abutment surface B71 of the nozzle holder 7. Thus, the positioning of the nozzle or the body 2 along the longitudinal axis M of the plasma arc burner head is determined. The centering surface A11 of the body 2 and the centering surface A71 of the nozzle holder 7 determine the centering of the nozzle or the body 2 in the nozzle holder 7. By this arrangement, a good centering is achieved. As already described, the cooling liquid flows through the space 10 between nozzle holder 7 and nozzle or body 2. This space is limited here by the surfaces A71 of the nozzle holder 7 and A13 of the nozzle and the circular ring 2.42 in the groove 2.10 and the stop surfaces B11 and B71 and surrounds here the entire outer circumference of this nozzle section. As a result, the large outer surface A13 of the nozzle is in contact with the cooling liquid, thereby improving the cooling. Here is also clear that avoided by the inventive solution damage to the circular ring 2.42 in groove 2.10 becomes. This is particularly important if, for example, projections are located on the centering surface A71.

FIG. 5 shows a liquid-cooled plasma arc burner head with the nozzle of FIG. 2 ,

The body 2 of the nozzle is fixed in a nozzle holder 7 and is fixed by a nozzle cap 3. In the inner cavity of the body 2, an electrode 1 is arranged. Between the electrode 1 and the body 2 there is a plasma gas guide 4 for plasma gas PG, which flows through the plasma gas guide 4, then through the space between the electrode 1 and the nozzle and finally from the nozzle opening 2.28. The plasma arc burner head further has a nozzle cap 5 which is held by a nozzle cap holder 8. Between the nozzle cap 3 and the nozzle cap 5, a secondary gas guide 6 is arranged for secondary gas SG. The secondary gas SG flows through openings (not shown) of the secondary gas guide 6, then through the space between the nozzle cap 3 and nozzle cap 5 and ultimately from the front opening 5.1 of the nozzle cap 5. There is also the possibility that the nozzle and nozzle cap 3 from a part consist. There are also plasma arc burner heads, which are operated without secondary gas. These then usually have no nozzle cap, No Düsenschutzkappenhalterung and no secondary gas guide.

As well as in connection with the FIG. 3 has been discussed in the plasma arc burner head of the FIG. 6 used nozzle similarity with the nozzle of FIG. 2 but there are also differences, in this example with regard to the seal in the front area. There is neither a groove 2.38 nor a round ring 2.40 inserted therein as in the nozzle of FIG. 2 or 5. Since indirect operation is also possible, current and heat transfer in the contact area between the nozzle and the nozzle cap is particularly important because of possible high currents, which are usually greater than 100A.

The cooling liquid flows through the cooling liquid flow WV through the nozzle holder 7, flows through the space 10 between the nozzle holder 7 and nozzle, through the groove 2.11 and the Centering A71 is formed, then flows through the groove B 12 of the nozzle or the body 2, which is in fluid communication with the groove 2.11 in the space between the nozzle 2 and nozzle cap 3 before it flows back through the coolant return WR.

The centering is in the arrangements according to Figures 5 and 6 even better than in FIG. 4 in that the centering of the nozzle takes place via the surfaces A11 and A12 with the surface A71 of the nozzle holder 7. The thus formed contact surface between the nozzle or body 2 and the nozzle holder 7 is larger, which additionally also the heat transfer and power transfer between the nozzle and nozzle holder 7. Likewise, no damage to the round ring 2.42 in the groove 2.10 (see FIG. 3 ).

The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential both individually and in any desired combinations for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1

electrode

2

body

2.1

first section

2.10

groove

2.2

second part

2.20

palm

2.22

outer surface

2.24

front end

2.26

rear end

2.28

nozzle opening

30.2

head Start

2:32

edge line

2:34

front projection

2:36

rear projection

2:38

groove

2:40

O-ring

2:42

O-ring

3

nozzle cap

4

Plasma gas management

5

Nozzle cap

6

Secondary gas guide

7

Injectors

8th

Nozzle protection cap holder

10

room

A11

centering

A12

area

A13

outer surface

A71

centering

B11

axial stop surface

B12

groove

B13

channels

B71

axial stop surface

D11

outer diameter

D12

outer diameter

D12a

outer diameter

D13

diameter

D21

outer diameter

L

axial total length

L1

axial length

L2

axial length

L12

length

L13

length

L14

length

M

longitudinal axis

M1

longitudinal axis

WR

Coolant return

WV

Coolant flow

Claims (21)

A nozzle for a liquid cooled plasma arc torch head, comprising: a body (2) having an overall axial length L, an inner surface (2.20) and an outer surface (2.22), a front (2.24) and a rear end (2.26) and a nozzle opening (2.28) at the front end (2.24), wherein the outer surface (2.22) of the body (2), starting from the rear end (2.26), has a substantially cylindrical first portion (2.1) with an axial length L1 at the rear end (2.26) of the body (2). a preferably circumferentially extending groove (2.10) for or with a circular ring (2.42) disposed therein, which is bounded to the rear end (2.26) of the body (2) by a projection (2.30) having an outer diameter D11 of the body ( 2), and at the front end a centering surface (A11) for a nozzle holder (7) which defines an outer diameter D12 of the body (2) and a second portion (2.2) adjoining the front end (2.24) an axial length L2 having an axial abutment surface (B11) for a nozzle holder at the boundary to the first section (2.1) defining an outer diameter D21 of the body (2), and at least in a partial section to the front end (2.24) of the body (2) tapers substantially conically, where: $$\mathrm{D}\mathrm{12}-\mathrm{D}\mathrm{11}\ge \mathrm{1}.\mathrm{5}\mathrm{mm}$$

and or $$\left(\mathrm{D}\mathrm{12}-\mathrm{D}\mathrm{11}\right)/\mathrm{D}\mathrm{12}\ge \mathrm{0}.\mathrm{07th}$$

A nozzle for a liquid cooled plasma arc torch, comprising: a body (2) having an overall axial length L, an inner surface (2.20) and an outer surface (2.22), a front (2.24) and a rear end (2.26) and a nozzle opening (2.28) at the front end (2.24), wherein the outer surface (2.22) of the body (2), starting from the rear end (2.26), has a substantially cylindrical first portion (2.1) with an axial length L1 at the rear end (2.26) of the body (2). a preferably circumferentially extending groove (2.10) for or with a circular ring (2.42) disposed therein, which is bounded to the rear end (2.26) of the body (2) by a projection (2.30) having an outer diameter D11 of the body ( 2), and at the front end (2.24) there is a centering surface (A11) for a nozzle holder (7) defining an outer diameter D12 of the body (2) and a second portion adjoining it towards the front end (2.24) ( 2.2) having an axial length L2 having an axial abutment surface (B 11) for a nozzle holder (7) at the boundary to the first section (2.1) defining an outer diameter D21 of the body (2) and at least in one Teilab cut to the front end (2.26) of the body (2) tapers substantially conically, in particular according to claim 1, for the length L12 of the distance between the axial abutment surface (B11) of the second section (2.2) and the nearest edge line (2.32) of the groove (2.10) and the length L13 of the distance between said edge line (2.32) and the rear end (2.26 ) of the body (2) $$\mathrm{L}\mathrm{12}/\mathrm{L}\mathrm{13}\ge \mathrm{3}.\mathrm{particularly\; preferred\; L}\mathrm{12}/\mathrm{L}\mathrm{13}\ge \mathrm{3}.\mathrm{3}$$

and or for the length L12 of the distance between the axial abutment surface (B11) of the second section (2.2) and the nearest edge line (2.32) of the groove (2.10) and the length L1 of the first section (2.1) $$\mathrm{L}\mathrm{12}/\mathrm{L}\mathrm{1}\ge \mathrm{0}.75\mathrm{and\; more\; preferably\; L}\mathrm{12}/\mathrm{L}\mathrm{1}\ge \mathrm{0}.\mathrm{77}.$$

and or
where is true $$\mathrm{D}\mathrm{12}/\mathrm{L}\mathrm{1}\le \mathrm{2}.\mathrm{Third}$$

Nozzle according to claim 1 or 2, characterized in that the outer diameter D12 is the largest outer diameter of the first section (2.1). Nozzle according to one of claims 1 to 3, characterized in that the outer diameter D21 is the largest outer diameter of the second portion (2.2). Nozzle according to one of the preceding claims, characterized in that the largest outer diameter of the first section (2.1) is smaller than the largest outer diameter of the second section (2.2). Nozzle according to one of the preceding claims, characterized in that at least one further groove (2.11) is located in the outer surface (2.22) of the first section (2.1). Nozzle according to claim 6, characterized in that the at least one further groove (2.11) has a cross-sectional area of at least 3 mm ² . Nozzle according to claim 6 or 7, characterized in that the further groove (2.11) extends in the circumferential direction of the body (2). Nozzle according to one of claims 6 to 8, characterized in that the further groove (2.11) extends in the circumferential direction of the body (2) through an angle in the range of about 20 ° to about 360 °. Nozzle according to one of claims 6 to 9, characterized in that the further groove (2.11) towards the front end (2.24) of the body (2) by a in the circumferential direction of the body (2) extending front projection (2.34), whose outer surface is formed by the centering surface (A11) is limited and / or the other Nut (2.11) towards the rear end (2.26) of the body (2) by a circumferentially of the body (2) extending rear projection (2.36) is limited. Nozzle according to claim 10, characterized in that the front projection (2.34) defines an outer diameter or a local largest outer diameter of the body (2) and the rear projection (2.36) defines an outer diameter or a local largest outer diameter, the outer diameters or local largest Outer diameter of the front (2.34) and rear projections (2.36) are the same size or differ by a maximum of about 0.2mm from each other. Nozzle according to one of the preceding claims, characterized in that in the second section (2.2) of the outer surface (2.22) there is / are at least one groove and / or bore and / or recess and / or other opening and / or channel which / which is in fluid communication with the first portion (2.1) of the outer surface (2.22). Nozzle according to one of Claims 6 to 12, characterized in that at least one groove and / or bore and / or recess and / or other opening and / or a channel are located in the second section (2.2) of the outer surface (2.22), the / in fluid communication with the further groove (2.11) in the first section (2.1) of the outer surface (2.22). Nozzle according to one of claims 1 to 5, characterized in that on the outer surface (2.22) of the body (2) between the groove (2.10) for a circular ring or with a circular ring arranged therein and the axial stop surface (B11) a circumferential receiving area for connection to a nozzle holder. Nozzle according to one of claims 6 to 13, characterized in that on the outer surface (2.22) of the body (2) between the groove (2.10) for a circular ring or with a circular ring arranged therein and the further groove (2.11) a circumferential receiving area for connection to a nozzle holder. Nozzle according to claim 14 or 15, characterized in that the receiving region has at least one radial projection and / or at least one radial recess. Arrangement of a nozzle holder and a nozzle according to one of the preceding claims. Arrangement according to claim 17, characterized in that the nozzle holder on its connecting side a cylinder wall with an end face abutting against the axial abutment surface (B11) of the nozzle, and with an inner surface on the centering surface (A11) of the nozzle preferably without or with has little play, has. Arrangement according to claim 17 or 18, characterized in that the nozzle holder on the inner surface of the cylinder wall has a receiving region of the nozzle complementary receiving area. A liquid-cooled plasma arc torch head comprising a nozzle according to any one of claims 1 to 16 or an assembly according to any one of claims 17 to 19. A liquid-cooled plasma arc torch comprising a nozzle according to any one of claims 1 to 16 or an assembly according to any one of claims 17 to 19.

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