EP2060160B1 - Plasma torch head, plasma torch shaft and plasma torch - Google Patents

Abstract

A plasma torch head, a plasma torch shaft and a plasma torch for providing a quick and simple possibility of changing the plasma torch head are described.

Description

The present invention relates to a plasma torch head comprising at least one fluid passage, an electrode, a nozzle, a power line, and a bearing surface on a support side, plasma torch shaft comprising at least a gas supply line, a power supply line, at least one fluid passage, a power line, and a bearing surface on one A support side and plasma torch having at least one gas, electrode, nozzle and power supply line supply line, the plasma torch comprising a plasma torch shaft including at least a first fluid passage, a first power line and a first bearing surface on a support side, and a plasma torch head includes at least a second fluid passage, a second power line and a second bearing surface on a support side, wherein the first and second bearing surfaces axially rest against each other and the at least one first Fluidd urchlaß is in fluid communication with the at least one second fluid passage and the first power line is in electrical communication with the second power line,

Plasma torches are known, which can be connected to one another from a plasma torch shaft and a plasma torch head, which can be connected to one another using a quick-change closure. consist. The plasma torch head contains the parts of the plasma torch that quickly wear out as a result of operation and need to be replaced more frequently. These are above all the electrode, the nozzle and the protective cap. But even in the case of changing uses of the plasma process, for example, between the cutting of structural steel and the cutting of stainless steel, the change from one plasma torch cutting head to another may be necessary. To realize this quickly, a quick-change lock is useful.

In G 081 32 660 a plasma torch is described, which consists of a plasma torch, an attachable connector and a plasma burner head. The plasma torch has an outstanding from the coupling surface locking pin and a correspondingly formed on the opposite coupling surface bore into which the locking pin is inserted with accurate radial adjustment. The plasma torch shaft and the connecting piece are connected by means of a slidable on the plasma torch sleeve sleeve with guide pins which are inserted into corresponding axially and radially formed guide grooves in the connecting piece, bayonet-like under axial pressure with radial movement of the sleeve. In both manual handling and automated systems, it is cumbersome to first thread the locking pin into the bore to then connect the other contacts for delivery and supply. In addition, damage can not be excluded.

In the DE 695 11 728 T2 For example, an alignment apparatus and method for an arc plasma torch system are described. The arc plasma burner consists of an arc plasma burner shaft and an arc plasma burner head. An overall positioning guide is used to initially align the arc plasma torch to a receptacle. The receptacle may be a bevelled edge. The receptacle has two apertures with a receiving end and a top dimensioned to receive alignment pins of one diameter. The alignment pins simultaneously have openings that are a gas or a liquid let through. The surface diameter is larger than the passage diameter and thereby can compensate for minor misalignments. A central passage is also sized and may also pass a gas or a liquid. Incorrect positioning may damage the alignment pins if, after threading the center passage, a force acts in the axial direction of the arc plasma torch. It may lead to leaks when using the alignment pins as a passageway for a gas or liquid. Damage to the alignment pins complicates the later positioning and merging of the components of the arc plasma torch, especially when low tolerance of the axes of the arc plasma torch head and the receptacle are required.

Another plasma burner head comprising a fluid passage, an electrode, a nozzle, a power line and a bearing surface on a support side is in the document US-A-5,624,586 disclosed.

In addition, in principle, the merging of two cylindrical body of a plasma torch is known. However, there is a risk of erroneous assignment of the connections and / or damage to the same.

In addition, a very high degree of centricity of the connection is often required. Then the game between an inner and an outer cylinder must be very low. This in turn makes the joining difficult.

The invention is therefore based on the object to provide a quick change facility for the plasma burner head.

An example of multi-pin connector (for the coupling of a plug and a socket) is in the document 48 425 168.9 proposed.

According to the invention, this object is achieved in the plasma burner head of the type mentioned above in that it has on its support side a cylinder wall with an outer surface and a circular surface, wherein on the outer surface circumferentially n _Ver equal radial recesses and n _Before equal radial projections are provided, wherein n _Ver , n _Vor ≥ 0 and n _Ver + n _Before ≥ 5, and in the case of n = 5, the sum of two adjacent center angles, among which the projections or recesses Projection and a depression are arranged offset with each other, not ≥ 180 ° and the five center angles are different sizes, or in the case of n> 5, the sum of two adjacent center angles, among which the projections or depressions or a projection and a recess are not ≥ 180 ° and the n> 5 center angles are different or at least two of n> 5 center angle are equal, then in each case the sum of the respective double occurring center angle and the adjacent to both sides of the center angle < 180 ° is.

The power line may be integrated in the fluid passages and / or carried out separately.

Usually, at least three fluid passages, namely for the supply of gas, such as plasma gas, and supply and return of coolant are provided.

In addition, this object is achieved in the plasma torch shaft of the aforementioned type characterized in that it comprises a cylindrical wall having an inner surface on its support side, on the inner surface circumferentially n same radial recesses are provided _{in front of} same radial projections and n _Ver wherein n _Before, n _Ver ≥0 and n _before + n _Ver ≥5, and in the case of n = 5, the sum of two adjacent center angles at which the protrusions and a recess are staggered with each other is not ≥180 ° and the five center-point angles are different in size, or in the case of n> 5, the sum of two adjacent center-point angles, among which the protrusions and a recess are offset from each other, is not ≥180 ° and the n > 5 center angles are different in size or at least two of the n> 5 center angle are the same size, in which case jewe ils is the sum of the respective doubly occurring midpoint angle and the center angle of which is adjacent to both sides <180 °.

The plasma torch heads and shafts may be plasma cutting or plasma welding heads or shafts.

Furthermore, this object is achieved in the plasma torch of the type mentioned above in that one of the plasma torch and the plasma burner head on its support side has a first cylinder wall with an outer surface and an annular surface and an outer diameter D21a and the other of the plasma torch and the plasma burner head on his bearing side has a second cylinder wall with an inner surface and an internal diameter D31a, whereby D31a> D21a and on the inner surface circumferentially radial _Before same projections and n _Ver n same radial indentations, wherein n _Before, n _Ver ≥0 and n _before + n _Ver = n ≥5, and on the outer surface an equal number of engaging therewith corresponding recesses or projections is provided, further, the projections and recesses are arranged so that when connecting the plasma torch shaft with the plasma burner head only the projections and depressions ge eng must be brought before the first bearing surface and the second bearing surface come to rest, and in the case of n = 5, the sum of two adjacent center angles, under which the projections or recesses or a projection and a recess are arranged offset to each other, not ≥180 ° and the five center angles are different in size, or in the case of n> 5, the sum of two adjacent center angles at which the projections and a recess are offset from each other is not ≥180 ° and the n> 5 center-point angles are of different sizes or at least two of the n> 5 center-point angles are equal, then in each case the sum of the respective doubly occurring center-point angle and the center angle adjacent thereto on both sides
<180 ° is.

The plasma torch may be a plasma cutting or welding torch.

In the plasma burner head, it may be provided that the sum of two adjacent center angles is ≤170 °. As a result, an even more stable system of annular surface and projections in the joining position is achieved.

According to a particular embodiment of the invention, n = 5 and the sum of two adjacent center-point angles is not repeated.

According to another particular embodiment, the plasma burner head contains four fluid passages.

Advantageously, the at least one fluid passage is provided with a plug.

Conveniently, the power line is also provided with a plug.

Furthermore, it can be provided that recesses are rectangular grooves. Of course, the grooves may also have any other shape, for example, arcuate, triangular, etc.

According to another particular embodiment, n _Ver ≥5.

Alternatively, it is also conceivable that n _Vor ≥5.

The dependent claims to the plasma torch cover advantageous developments of the same.

According to a particular embodiment of the invention, a supply line for secondary gas is additionally provided and the plasma burner shaft contains four fluid passages.

Conveniently, the at least one fluid passage is provided with a bushing.

Conveniently, the power line is also provided with a socket.

For example, a circumferential radially outwardly extending chamfer may be provided on the inner surface of the cylinder wall in the direction of the support side in front of the projections. By this the assembly is facilitated, since at the beginning of the assembly, a larger diameter is available.

The dependent claims to the plasma burner relate to advantageous developments of the same.

According to a particular embodiment, a supply line for secondary gas is additionally provided and the plasma burner shaft contains four first fluid passages and the plasma burner head has four second fluid passages.

Advantageously, the coolant is water.

Conveniently, the at least one first fluid passage is provided with a bushing.

Furthermore, the at least one second fluid passage is expediently provided with a plug.

Advantageously, the first power line is provided with a socket.

In addition, the second power line is conveniently provided with a plug.

According to a particular embodiment of the invention, a cohesion device is provided for holding together the plasma burner head and the plasma burner shaft.

Advantageously, the cohesion device comprises a clamping sleeve.

For example, a particular embodiment of the plasma torch is characterized in that the plasma burner head has the first cylinder wall and plasma torch shaft has the second cylinder wall.

The invention is based on the surprising finding that a simple and quick assembly of the plasma burner head and the plasma torch shaft without tilting is achieved by the special number and arrangements of projections and corresponding recesses. The annular surface must simply be brought into abutment with the projections, that is brought into a joining position, and thereafter rotated relative to the projections, until the joining position is reached, in which the projections and recesses engage with each other with an axially acting force. This is particularly advantageous in situations where the plasma torches are clamped and not optically accessible. The quick change of the plasma burner head can be done blind, so to speak.

In addition, the invention provides a quick change port between plasma torch head and plasma torch shaft with anti-rotation, low tolerance between the axes of the plasma torch head and plasma torch shaft and high centricity.

The fluid passages for both the gas, such as plasma and secondary gas, as well as for the cooling medium, can also be used for power transmission.

Figur 1

eine Seitenansicht eines vorderen Teils eines Plasmaschneidbrenners vor dem Zusammenfügen von Plasmaschneidbrennerkopf und Plasmaschneidbrennerschaft gemäß einer besonderen Ausführungsform der vorliegenden Erfindung teilweise im Schnitt;

Figur 2

eine Seitenansicht des vorderen Teils des Plasmaschneidbrenners während des Zusammenfügens des Plasmaschneidbrennerkopfes und des Plasmaschneidbrennerschaftes in der Fügestellung teilweise im Schnitt;

Figur 3a

eine Draufsicht auf den Plasmaschneidbrennerschaft von der Auflageseite;

Figur 3b

eine Draufsicht auf den Plasmaschneidbrennerkopf von der Auflageseite;

Figur 4a

eine Schnittansicht vom Plasmaschneidbrennerkopf und -schaft in der Fügeposition im Bereich der Vertiefungen und Vorsprünge;

Figur 4b

eine Schnittansicht vom Plasmaschneidbrennerkopf und -schaft in der Fügestellung im Bereich der Vertiefungen und Vorsprünge;

Figur 5

eine Seitenansicht des vorderen Teils des Plasmaschneidbrenners nach dem Zusammenfügen des Plasmaschneidbrennerkopfes und Plasmaschneidbrennerschaftes teilweise im Schnitt;

Figur 6

einen Ausschnitt aus Figur 2;

Figur 6a bis 6f

ein Detail von Figur 6 in verschiedenen Ausführungsformen;

Figur 7

unterschiedliche Ausführungsformen von Vertiefungen und/oder Vorsprüngen;

Figur 8

Einzelheiten von Figur 4b; und

Figur 9

eine Ansicht ähnlich wie Figur 4a.

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

FIG. 1

a side view of a front portion of a plasma cutting torch prior to assembly of plasma cutting torch head and plasma cutting torch according to a particular embodiment of the present invention partially in section;

FIG. 2

a side view of the front part of the plasma cutting torch during the assembly of the plasma cutting torch head and the plasma cutting torch shaft in the joining position partially in section;

FIG. 3a

a plan view of the plasma cutting torch from the support side;

FIG. 3b

a plan view of the plasma cutting burner head from the support side;

FIG. 4a

a sectional view of the plasma cutting burner head and shaft in the joining position in the region of the recesses and projections;

FIG. 4b

a sectional view of the plasma cutting torch head and shaft in the joint in the region of the recesses and projections;

FIG. 5

a side view of the front portion of the plasma cutting torch after the assembly of the plasma cutting torch head and plasma cutting torch shaft partially in section;

FIG. 6

a section from FIG. 2 ;

FIGS. 6a to 6f

a detail of FIG. 6 in various embodiments;

FIG. 7

different embodiments of recesses and / or projections;

FIG. 8

Details of FIG. 4b ; and

FIG. 9

a view similar to FIG. 4a ,

As is clear from the Figures 1 and 2 1, a plasma cutting torch 1 comprises a plasma cutting torch head 2 and a plasma cutting torch shaft 3. As can be seen by reference to FIG FIGS. 3a and 3b such as FIG. 5 2, the plasma cutting burner head 2 has a first support surface (not shown), a water supply plug 241, a water return plug 242, a plasma gas plug 243, a secondary gas plug 244, and a pilot power plug 245. The plugs 241 to 245 are provided with holes (not marked) for the passage of gas or liquids.

The plasma cutting burner shaft 3 has a second support surface (not shown), a water return bushing 341, a water feed bushing 342, a plasma gas bushing 343, a secondary gas bushing 344, and a pilot flow bushing 345.

The plugs 241 to 245 and the sockets 341 to 345 form a quick change interface. Of course, alternatively, the plugs or a portion thereof may be disposed on the plasma cutting firing shaft and the bushings on the plasma cutting firing head. The necessary for the supply fluid passages and power lines in the plasma cutting burner head 2 and in the plasma cutting torch 3 are not shown in detail.

The plasma cutting burner head 2 has on its support side a first cylinder wall 21 with an outer surface 21a and an annular surface 22 and an outer diameter D21a. The plasma cutting burner shaft 3 has on its support side a second cylinder wall 31 with an inner surface 31a and an inner diameter D31a, where D31a> D21a. For introducing the plasma cutting burner head 2 into the plasma cutting burner shaft 3, the latter has a large clearance S in the joining position (see FIGS. 6a, 6d, 6e and 6f ).

As reflected by the FIGS. 3a and 3b shows, the plasma cutting burner shaft 3 on its inner surface 31a circumferentially five identical rectangular lugs 331, 332, 333, 334 and 335 and the plasma cutting burner head 2 has five same correspondingly shaped and arranged rectangular grooves 231, 232, 233, 234 and 235 on its outer surface 21a on. The lugs 331 to 335 and grooves 231 to 235 are arranged in the axial direction so that when connecting the plasma cutting burner shaft 3 with the plasma cutting burner head 2, only the grooves and lugs are brought into engagement before the first bearing surface and the second bearing surface come to rest.

When introducing the plasma cutting burner head 2 into the plasma cutting burner shaft 3, the annular surface 22 of the plasma cutting burner head 2 usually strikes the lugs 331 to 335 (see FIG FIG. 4a ). The plasma cutting burner head 2 and the plasma cutting burner shaft 3 are thus in the joining position.

Since the sum of two adjacent midpoint angles is the midpoint angles α, β, γ, δ and ε (see FIG. 8 ), under which the grooves 231 to 235 are arranged, is not ≥180 ° and the five center angles are of different sizes, the lugs 331 to 335 with the broken by the grooves 231 to 235 annular surface 22 of the plasma cutting burner head in each position except the Connection (see FIG. 4b ) to each other a virtual surface A. The grooves 231 to 235 are always arranged with the exception of the joining position so that the resting on the annular surface 22 of the plasma cutting burner head 2 noses (in FIG. 4a the lugs 331, 333, 334 and 335) form a square with the surface A, in which the center axis M of the plasma cutting burner 1 is located (see FIG. 4a ).

Unless additionally the condition is satisfied that the sum of two adjacent center-point angles of the center-point angles α, β, γ, δ and ε repeats, it can also only lead to the formation of a triangular area A, as shown in FIG FIG. 9 is shown.

Due to the fact that the central axis M of the plasma cutting burner 1 is located in the area A, the plasma cutting burner shaft 3 and the plasma cutting burner head 2 can be rotated against each other as desired until the joining position has been reached. When the joining position is reached, the plasma cutting burner head 2 slips into the plasma cutting burner shaft 3 when the force is acting axially, and both can be inserted into one another (see FIG Figures 2 . 4b and 5 ).

By turning a clamping sleeve 25 is on the internal thread 251 and the external thread 35 of the plasma cutting torch shaft 3, a further axial force on the Interfaces exercised until the Endfügestellung (see FIG. 5 ) is reached. There, the diameter of the plasma cutting torch shaft is reduced from D31a to D31b, whereby the clearance S is reduced or even eliminated and the centricity is increased. Of course, this can also be realized by other mechanisms, for example a bayonet closure or another tightening device.

The grooves 231 to 235 are usually larger than the lugs 331 to 335, since otherwise an assembly would not be possible. The measure B indicates the average width of the grooves and noses and is calculated (see FIG. 3a and 3b ) as follows $$B=\frac{B2+B3}{2}\mathrm{,}$$

The same design of the grooves or lugs has a reduction of the manufacturing effort compared to an embodiment with different lugs and thus grooves, would be sufficient in the three grooves or lugs. It can then be worked with a single tool.

The inner surface 31a may be designed differently to simplify the joining process. It can have a larger clearance S with a cylindrical shape ( FIG. 6a ), over an angle F ( FIG. 6b ) over a radius ( FIG. 6c ) or a combination of the individual elements ( Figures 6d, 6e and 6f ). It is sufficient that the grooves and noses have a substantially similar shape and size. In fact, they need only be designed in such a way that the condition is met by the polygon, for example triangle or quadrilateral.

The dimensions may look like this, for example:

• D: 25 bis 100mm
• F: 15 bis 60°

$$S=\frac{D31a-D21a}{2}$$

• S: 0,2 bis 0,7mm
• R: 1 bis 5mm.

The mean diameter D of the first cylinder wall and the second cylinder wall is calculated as follows (see FIG. 1 ): $$D=\frac{D31b+D21a}{2}\mathrm{,}$$

• D: 25 to 100mm
• F: 15 to 60 °

$$S=\frac{D31a-D21a}{2}$$

• S: 0.2 to 0.7mm
• R: 1 to 5mm.

• α = 75°
• β = 70°
• γ = 90°
• δ = 65°
• ε = 60°.

In the FIG. 8 the parameters look like this:

• α = 75 °
• β = 70 °
• γ = 90 °
• δ = 65 °
• ε = 60 °.

$$b=\frac{\mathrm{\Pi }\times D\times \beta }{360°}\mathrm{in\; mm\; usw}\mathrm{.}$$

In addition, in FIG. 8 the distances a, b, c, d and e between the lugs / grooves shown. These are the distances between the symmetry axes of the noses and grooves 231 to 235 on average diameter D. They are calculated according to the formula: $$a=\frac{\mathrm{\Pi }\times D\times \alpha }{360°}\mathrm{in\; mm}$$

$$b=\frac{\mathrm{\Pi }\times D\times \beta }{360°}\mathrm{in\; mm,\; etc}\mathrm{,}$$

• α = 60°
• β = 95°
• γ = 80°
• δ = 75°
• ε = 50°.

$$\mathrm{\alpha }\mathrm{+}\mathrm{\beta }\mathrm{=}\mathrm{\gamma }\mathrm{+}\mathrm{\delta }$$

$$60°+95°=80°+75°=155°\mathrm{.}$$

In FIG. 9 the angles are chosen as follows:

• α = 60 °
• β = 95 °
• γ = 80 °
• δ = 75 °
• ε = 50 °.

$$\mathrm{\alpha }\mathrm{+}\mathrm{\beta }\mathrm{=}\mathrm{\gamma }\mathrm{+}\mathrm{\delta }$$

$$60°+95°=80°+75°=155°\mathrm{,}$$

Consequently, the sum of two adjacent midpoint angles, namely α and α, and γ and δ is repeated.

FIG. 7 shows examples of possible designs of pairs of lugs 331 and grooves 231. However, the lugs could also be used as grooves and the grooves as lugs.

The features of the invention disclosed in the present 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.

Claims (22)

1. Plasma torch head (2), comprising at least one fluid passage, one electrode, one nozzle, one power line and a support area on a contact face, characterised in that
   on its contact face it has a cylinder wall (21) with an outer surface (21a) and an annular surface (22), while on the periphery of the outer surface (21a) identical radial indentations n_Ver and identical radial projections n_Vor are provided, where n_Vor, n_Vor ≥ 0 and n_Ver + n_Vor ≥ 5, and
   if n = 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the five angles at centre (α, β, γ, δ, ε) are of different sizes,
   or
   if n > 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the n > 5 angles at centre (α, β, γ, δ, ε) are of different sizes or at least two of the n > 5 angles at centre (α, β, γ, δ, ε) are the same size, in which case the sum of the twice-occuring respective angle at centre (α or β or γ or δ or ε) and the adjacent angles at centre at both sides thereof (α and γ or β and 8 or γ and ε or δ and α or ε and β) < 180°.
2. Plasma torch head (2) according to claim 1, characterised in that the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or e and α) ≤ 170°.
3. Plasma torch head (2) according to claim 1 or 2, characterised in that n = 5 and the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and e or ε and α) does not recur.
4. Plasma torch head (2) according to one of the preceding claims, characterised in that the indentations are rectangular grooves (231, 232, 233, 234, 235).
5. Plasma torch head according to one of the preceding claims, characterised in that n_Ver ≥ 5.
6. Plasma torch head (2) according to one of claims 1 to 4, characterised in that n_Vor ≥ 5.
7. Plasma torch shaft (3), comprising at least one supply line for a gas, a power supply line, at least one fluid passage, a power line and a support area on one contact face,
   characterised in that
   on its contact face it has a cylinder wall (31) with an inner face (31a), while on the periphery of the inner surface (31a) identical radial projections n_Vor and identical radial indentations n_Ver are provided, where n_Vor, n_Ver ≥ 0 and n_Vor + n_Ver ≥ 5, and
   if n = 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the five angles at centre (α, β, γ, δ, ε) are of different sizes,
   or
   if n > 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and e or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the n > 5 angles at centre (α, β, γ, δ, ε) are of different sizes or at least two of the n > 5 angles at centre (α, β, γ, δ, ε) are the same size, in which case the sum of the twice-occuring respective angle at centre (α or β or γ or δ or ε) and the adjacent angles at centre at both sides thereof (α and γ or β and δ or γ and ε or δ and α or ε and β) < 180°.
8. Plasma torch shaft (3) according to claim 7, characterised in that the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α) ≤ 170°.
9. Plasma torch shaft (3) according to claim 7 or 8, characterised in that n = 5 and the sum of two adjacent angles at centre (α and γ or β and δ or γ and ε or s and β) does not recur.
10. Plasma torch shaft (3) according to one of claims 7 to 9, characterised in that the projections are rectangular lugs (331, 332, 333, 334, 335).
11. Plasma torch shaft (3) according to one of claims 7 to 10, characterised in that on the inner surface (31a) of the cylinder wall (31) in the direction of the contact face, before the projections and/or indentations, a peripheral chamfer, extending radially outwards, is provided.
12. Plasma torch shaft (3) according to one of claims 7 to 11, characterised in that n_Vor ≥ 5.
13. Plasma torch shaft (3) according to one of claims 7 to 11, characterised in that n_Ver ≥ 5.
14. Plasma torch (1) with at least one supply line for a gas, an electrode, a nozzle and a power supply line, wherein the plasma torch (1) comprises a plasma torch shaft (3), which contains at least one first fluid passage, a first power line and a first support area on a contact face, and
    comprises a plasma torch head (2), which contains at least a second fluid passage, a second power line and a second support area on a contact face, wherein the first and second support areas are supported axially with respect to each other and the at least one first fluid passage is in fluid connection with the at least one second fluid passage and the first power line is in electrical contact with the second power line,
    characterised in that
    one of the plasma torch shaft (3) and the plasma torch head (2) has, on its contact face, a first cylinder wall (21) with an outer surface (21a) and an angular surface (22) and an external diameter D21a and the other of the plasma torch shaft (3) and the plasma torch head (2) has, on its contact face, a second cylinder wall (31) with an inner surface (31a) and an internal diameter D31a, whereby D31a > D21a and ;on the inner surface (31a) peripheral n_Vor identical radial projections and n_Ver identical radial indentations, wherein n_Vor, n_Ver ≥ 0 and n_Vor + n_Ver = n ≥ 5, and on the outer surface (21a) an equal number of corresponding indentations and projections are provided respectively, interacting therewith, and furthermore the projections and indentations are arranged in such a way that when the plasma torch shaft (3) is connected with the plasma torch head (2), the projections and indentations must firstly be brought into engagement before the first support area and the second support area come to rest, and
    if n = 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the five angles at centre (α, β, γ, δ, ε) are of different sizes,
    or
    if n > 5 the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α), under which the projections and indentations or one projection and one indentation respectively are arranged offset with respect to one another, is not ≥ 180° and the n > 5 angles at centre (α, β, γ, δ, ε) are of different sizes or at least two of the n > 5 angles at centre (α, β, γ, δ, ε) are the same size, in which case the sum of the twice-occuting respective angle at centre (α or β or γ or δ or ε) and the angles at centre adjacent both sides thereof (α and γ or β and δ or γ and α or δ and α or ε and β) < 180°.
15. Plasma torch (1) according to claim 14, characterised in that the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α) ≤ 170°.
16. Plasma torch (1) according to claim 14 or 15, characterised in that n = 5 and the sum of two adjacent angles at centre (α and β or β and γ or γ and δ or δ and ε or ε and α) does not recur.
17. Plasma torch (1) according to one of claims 14 to 16, characterised in that the plasma torch head (2) has the first cylinder wall (21) and the plasma torch shaft (3) has the second cylinder wall (31).
18. Plasma torch (1) according to one of claims 14 to 17, characterised in that the indentations are rectangular grooves (231, 232, 233, 234, 235).
19. Plasma torch (1) according to one of claims 14 to 18, characterised in that on the inner surface (31a) of the second cylinder wall (31) in the direction of the contact face, before the projections and/or indentations, a peripheral chamfer, extending radically outwards, is provided.
20. Plasma torch (1) according to one of claims 14 to 19, characterised in that n_Ver ≥ 5.
21. Plasma torch (1) according to one of claims 14 to 19, characterised in that n_Ver ≥ 5.
22. Plasma torch (1) according to one of claims 14 to 21, characterised in that a binding device is provided to bind together the plasma torch head and the plasma torch shaft (3).

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