EP2640167B1 - Plasma electrode for a plasma cutting device - Google Patents

Description

The invention relates to a plasma electrode for a plasma cutting device according to the preamble of patent claim 1.

Such a plasma electrode is, for example, with the subject of WO 2009/070 362 A1 known. This disclosure is intended to be fully within the scope of the present invention description.

In order to master the cooling problem of plasma electrodes, said document proposes to arrange a cooling tube in the interior of an approximately hollow-cylindrical electrode body, whose front end face is positioned with a spacer which is inserted at the bottom of the electrode body.

The cited document also generally discloses a plasma electrode having a hollow cylindrical electrode body, on the front side of which is arranged in the interior of the electrode, arranged on the front side, central core holder for an electrode core is arranged.

The electrode core is z. B. formed as a hafnium core and is held in the electrode-side core holder. With the publication EP I 933 607 A1 a plasma electrode is shown, in FIG. 2 respectively. FIG. 3 a cooling tube is held within a burner body. The holder of the cooling tube 5 is effected in that in the region of the nozzle tip, a shoulder 2a is present, which spaces the nozzle tube relative to the nozzle bottom. The cooling tube 5 is thus not kept at a distance from the core holder, but at a distance from the electrode cap.

With the publication DE 10 2009 059 108 A1 For example, an electrode with a cooling tube for a plasma cutting device is shown. On the inside of the electrode body is in this case at least one stop for a cooling tube, which cooperates with the front side of the cooling tube. This makes it possible to achieve a good circulation of the cooling liquid in the lower region of the electrode body. However, the cooling tube is held by an electrode body and not by the core holder. With the publication US Pat. No. 5,416,296 discloses a plasma electrode for a plasma cutting device, which consists of an approximately hollow cylindrical electron body and at its front side into the interior the electrode directed, frontally arranged, centric core holder for Cooling tube, which cooperates with the front side of the cooling tube. This makes it possible to achieve a good circulation of the cooling liquid in the lower region of the electrode body. However, the cooling tube is held by an electrode body and not by the core holder.

With the publication US 2004/0200810 A1 a holder for a cooling tube within a plasma torch is shown. According to the FIGS. 4a to 9a is located in most embodiments of the cooling tube means, by which the cooling tube is spaced in the region of the electrode tip and thereby a circulation of the cooling liquid is possible.
However, none of the embodiments shows that the cooling tube is held securely by the core holder.

With the publication US 2008/0093346 A1 For example, a plasma cutting apparatus and a plasma torch cooling apparatus are shown. According to the FIGS. 5 to 7 Here, a cooling tube is disposed within a burner body, wherein the end face of the cooling tube cooperates with a core holder. In this case, however, only the cooling tube lies with its end face in the axial direction on the core holder, which, however, no position assurance is guaranteed. Rather, the cooling tube is held in the upper region of the burner and is thus not secured in position in the lower region.

The publication US 2008/0116179 A1 shows a method and apparatus for a plasma torch. With the FIGS. 13 to 24 Bottom-side spacers are described, which are inserted into the front side in the inner region of the electrode and thereby space the cooling tube in the axial direction of the electrode body bottom.
However, none of the exemplary embodiments shown there shows that the cooling tube is at least partially held secured on the core holder.

With the publication WO2012 / 074591 A1 An electrode for a plasma torch is shown. According to the FIGS. 6 to 15 has the cooling tube, which is arranged in the interior of the burner, in the upper and in the lower region in each case a thread, which act in the lower area with the core holder and in the upper area with the electrode holder together. The cooling tube is thus bound to the present device and can not be used in other plasma cutting devices. Furthermore, this device is very expensive to produce, since threads must be present both in the region of the core holder and in the upper electrode body region.

With the publication US 5,416,296 is a plasma electrode for a plasma cutting device, which consists of an approximately hollow cylindrical electron body and on whose front side a directed into the interior of the electrode, frontally arranged, centric core holder is arranged for an electrode core. In the interior of the electrode body is a cooling tube through which an axial flow of cooling liquid flows. The electrode core holder has on its outer surface ribs or grooves or holes through which its surface is increased. However, the cooling tube is fixed with its end face on the bottom of the electrode body and is thus not held positionally secured against the core holder.

The publication US 6,362,450 B1 shows a cooling gas duct for a plasma cutting torch. According to the FIGS. 1 to 3 a gas guide is shown within a burner body, wherein a valve spindle to swirl the gas passed through and thus a better cooling is to be achieved. Although this valve spindle with the end face in the axial direction on the core holder, but no radial position assurance between the core holder and the valve stem is guaranteed.

A disadvantage of the cited references, however, is that a separate from the electrode body part, namely a spacer must be used, which must be placed as a separate part in the interior of the electrode body, which is associated with a high assembly cost.

The invention is therefore the object of developing a plasma electrode for a plasma cutting device and arranged in the interior of the plasma electrode cooling tube so that the mounting and mounting of the cooling tube is substantially simplified. Furthermore, the cooling of the electrode core should be improved.
To solve the problem, the invention is characterized by the technical teaching of claim 1, 2 and independent claim 13.
An essential feature of the invention is that a separate part, such as a spacer or the like, waived and instead the cooling tube is fixed with its front, the electrode core side facing directly on the electrode-side core holder for holding the electrode core.

It is a position-secured holder of the front end of the cooling tube directly to the core holder of the electrode body. This

Core holder is intended for holding the electrode core and must be cooled because of the high working temperature of the electrode core.
Accordingly, the invention relates to a completely new positioning for the mounting of a cooling tube, because until now it was only known, the cooling tube to back stops (s. FIG. 22 the cited document) to be positioned on the electrode body or just on the front side in the electrode body interior spacers arranged, however, which must be introduced as a separate part.

With the given technical teaching, there is thus the advantage that a direct position-secured mounting of the front end of the cooling tube takes place on the core holder receiving the electrode core in the electrode body. Although it was previously also known in the interior of the electrode body, in the vicinity of the core holder, namely radially outwardly of the core holder, z. B. on the inside of the electrode body, assigned to attach stops that were part of the electrode body. Disadvantage of the attachment of such attacks, however, is their difficult and expensive production.

Due to the technical teaching of the invention that the cooling tube at least partially overlaps the electrode-side core holder and, so to speak, is secured in position on the outer circumference of the electrode-side core holder, there is accordingly the advantage that separate holding or layer securing means can be dispensed with.

In the invention, it is provided that the core holder is designed as a conical body directed into the interior of the electrode body, the conical surfaces of which taper from the bottom of the electrode body in the axial direction to the rear (top).

This has the advantage that an excellent, automatic centering of the cooling tube takes place on the cone holder designed as a core holder, because the cooling tube is simply plugged with its front end on the cone body of the core holder, so that a part of the body of the core holder extends into the interior of the cooling tube ,
The cooling tube thus centered automatically on the outer circumference of the core holder designed as a cone body.
It should also be noted that the front side of the cooling tube on the core holder is a position assurance and the cooling tube is preferably connected to a preferably designed as a screw or plug connection preferably at the rear end of the electrode body with this releasably connected.

However, the invention is concerned only with the front, the position assurance serving holder of the cooling tube to the electrode-side core holder, which also serves to hold the electrode core.

As the cooling tube is detachably connected to the electrode body itself at the rear end, according to a variety of embodiments (screw, connectors, bayonet and the like) is possible.

If - according to the technical teaching of claim 1 - the position assurance of the front end of the cooling tube takes place on the reaching into the interior of the electrode core holder, it must be ensured that the guided in the interior of the cooling tube liquid flow is deflected in the region of the core holder, so in the Area of protection between the front end of the cooling tube and the electrode-side core holder for a leakage of the cooling liquid and a diversion of the cooling liquid must be ensured.

Therefore, the invention provides according to a further preferred embodiment, that at least one recess leading to the cooling liquid is arranged on the outer circumference of the core holder.

This means that the core holder does not sealingly close the front end of the cooling tube, but that in the region of this position assurance one or more, the cooling liquid recesses are present, which are able to forward the guided inside the cooling tube cooling liquid along the core holder and preferably to lead to the annular groove bottom of the electrode body, where the cooling liquid flow is diverted and guided in the interior of the cooling tube cooling liquid is deflected from the interior of the cooling tube in the outer annular gap between the outer surface of the cooling tube and the inner surface of the electrode body.

For the formation of such the cooling liquid leading, in the recess of the electrode body itself arranged recesses, there are a variety of different embodiments. A particular advantage of these recesses is that the cooled surface of the core holder is increased in a multiple compared to a smooth surface and thus a much better cooling is given by multiplication of the electrode core used in the core holder.

Therefore, separate protection is required for this particular embodiment of the core holder with its enlarged surface, regardless of whether it is designed as a holder and centering for a cooling tube.

In a first embodiment of the invention, it is provided that the core holder is not formed as a truncated cone, but as at least one side flattened truncated cone, so through the flattening thus formed the coolant flow can pass into the interior of the electrode body via the outer circumference of the core holder.

In this case, however, a two-sided flattening, which is mirror-symmetrical with respect to the longitudinal center axis of the core holder designed as a truncated cone, is preferred.

The invention is not limited to that of the core holder is formed as a flattened truncated cone, which is formed substantially rotationally symmetrical.

It can be used all other embodiments, which include that in the region of the core holder cooling liquid leading recesses are provided which are able to lead out in the interior of the cooling tube in the axial direction guided coolant in the area of the position assurance of the cooling tube on the core holder from the cooling tube and to introduce into the interior of the electrode body.

In a preferred embodiment of the invention, it is therefore provided that arranged in the core holder one or more recesses are arranged parallel to the conical surface of the conical core holder, because this results in particularly favorable flow conditions.

However, the invention is not limited thereto. It can also be used recesses, which are directed at an angle to the conical surface of the conical core holder.

In a preferred embodiment of the invention, it is otherwise provided that the at least one recess arranged in the core holder is designed either as a half-open longitudinal groove or as a half-open bore channel or as a radially outwardly open segment recess.

However, it is preferred if more than one recess passes through the outer periphery of the core holder, in order to achieve the most favorable and full-surface coolant flow over the entire circumference of the core holder. In this case, it is then preferred that, in the case of a plurality of recesses leading to the cooling liquid, these recesses are distributed uniformly around the circumference of the core holder.

Of course, it may also be provided in another embodiment of the invention that the front end of the cooling tube does not sealingly rests on the outer circumference of the core holder, but that although there is a support, but the cooling tube in this area still radially outwardly directed slots, Has holes or recesses.

In the following exemplary embodiments, various exemplary embodiments relating to the mounting of the electrode core in the core holder will be described. Applies to all embodiments that the directed into the interior of the cooling tube and the electrode end face of the core holder is flattened and the rear end side of the electrode core is flush with this end face.

In another embodiment applies to all embodiments that the directed in the interior of the cooling tube and the electrode end face of the core holder is also flattened, but the electrode core protrudes with an elongated approach into the interior of the cooling tube.

This latter embodiment ensures that the electrode core - the cooling of which is decisive - protrudes into the interior of the cooling tube in contact with the liquid, thus providing even better cooling.

After the subject matter of claim 2 has been recognized that the surface cooling of the core holder can be significantly improved by this surface is enlarged with outwardly open grooves or holes, It forms the surface of the core holder magnifying cooling channels, which are preferably aligned in the axial direction are. However, these cooling channels can also - to further extend the length of the respective cooling channel - also helically, in the manner of threads increase the outer circumference of the core holder. According to other unclaimed embodiments, the core holder can in this case be cylindrical or conical in profile or provided with any other profile. Also, it does not matter in the idea of enlarging the cooling surface of the core holder whether the cooling tube rests on a bearing surface of the core holder in a positionally secured manner or overlaps only with the formation of an annular gap of the core holder.

In order to obtain such an enlarged surface, it has been recognized that it is desirable to provide such semi-open grooves or half-open bores by either machining or upsetting. A third embodiment relates to the attachment of a thread on the outer circumference of the core holder, which can be done either by a thread cutting or a compression forming.

In other embodiments, claims claim that the front end face of the cooling tube is either smooth and undurchbrochen or provided with lateral slots or holes.

The subject invention of the present invention arises only from the subject matter of the individual claims. In the following, the invention will be explained in more detail with reference to drawings illustrating several execution paths. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

• Figur 1: schematisiert einen Längsschnitt durch eine erste Ausführungsform einer Plasmaelektrode
• Figur 2: Schnitt durch die Plasmaelektrode entlang der in Figur 1 dargestellten Schnittlinie
• Figur 3: schematisiert eine räumliche Darstellung der Lagensicherung des vorderen Endes des Kühlrohres auf einer konusförmigen Kernhalter des Elektrodenkörpers
• Figur 4: einen Längsschnitt durch einen Elektrodenkörper mit einer anderen Halterung des Elektrodenkerns
• Figur 5: Schnitt durch die Plasmaelektrode in Höhe der eingezeichneten Schnittlinie
• Figur 6: Längsschnitt durch eine Plasmaelektrode mit einer zweiten Ausführungsform des Kernhalters
• Figur 7: Querschnitt durch die Plasmaelektrode in Höhe der in Figur 6 eingezeichneten Schnittlinie
• Figur 8: Längsschnitt durch eine dritte Ausführungsform einer Plasmaelektrode
• Figur 9: Querschnitt durch die Plasmaelektrode nach Figur 8
• Figur 10: Längsschnitt durch eine vierte Ausführungsform einer Plasmaelektrode
• Figur 11: Querschnitt durch die Plasmaelektrode nach Figur 10
• Figur 12: Längsschnitt durch eine fünfte Ausführungsform einer Plasmaelektrode
• Figur 13: Querschnitt durch die Plasmaelektrode nach Figur 12
• Figur 14: Längsschnitt durch eine sechste Ausführungsform einer Plasmaelektrode
• Figur 15: Querschnitt durch die Plasmaelektrode nach Figur 14
• Figur 16: Längsschnitt durch eine siebte Ausführungsform einer Plasmaelektrode
• Figur 17: Querschnitt durch die Plasmaelektrode nach Figur 16
• Figur 18: Längsschnitt durch eine achte Ausführungsform einer Plasmaelektrode
• Figur 19: Querschnitt durch die Plasmaelektrode nach Figur 18
• Figur 20: Längsschnitt durch eine neunte Ausführungsform einer Plasmaelektrode
• Figur 21: Querschnitt durch die Plasmaelektrode nach Figur 20
• Figur 22: Längsschnitt durch eine zehnte Ausführungsform einer Plasmaelektrode
• Figur 23: Querschnitt durch die Plasmaelektrode nach Figur 22
• Figur 24: Längsschnitt durch eine elfte Ausführungsform einer Plasmaelektrode
• Figur 25: Querschnitt durch die Plasmaelektrode nach Figur 24
• Figur 26: Längsschnitt durch eine zwölfte Ausführungsform einer Plasmaelektrode
• Figur 27: Querschnitt durch die Plasmaelektrode nach Figur 26
• Figur 28: Ein schematisiertes Ausführungsbeispiel im Schnitt, das eine Stauch-Umformung der zentrischen Kernhalter mit einem Stauchwerkzeug zeigt.
• Figur 29: Der Kernhalter nach Figur 28 nach der Stauchumformung
• Figur 30: Ein weiteres schematisiertes Ausführungsbeispiel mit einer Kernhalter, an deren Außenumfang Kühlkanäle in Form von Gewindegängen angeformt sind.

Show it:

• FIG. 1 : Schematically illustrates a longitudinal section through a first embodiment of a plasma electrode
• FIG. 2 : Section through the plasma electrode along the in FIG. 1 illustrated section line
• FIG. 3 : Schematically illustrates a spatial representation of the position assurance of the front end of the cooling tube on a cone-shaped core holder of the electrode body
• FIG. 4 a longitudinal section through an electrode body with another holder of the electrode core
• FIG. 5 : Section through the plasma electrode at the level of the cut line drawn
• FIG. 6 : Longitudinal section through a plasma electrode with a second embodiment of the core holder
• FIG. 7 : Cross section through the plasma electrode at the level of FIG. 6 drawn cutting line
• FIG. 8 : Longitudinal section through a third embodiment of a plasma electrode
• FIG. 9 : Cross section through the plasma electrode after FIG. 8
• FIG. 10 : Longitudinal section through a fourth embodiment of a plasma electrode
• FIG. 11 : Cross section through the plasma electrode after FIG. 10
• FIG. 12 : Longitudinal section through a fifth embodiment of a plasma electrode
• FIG. 13 : Cross section through the plasma electrode after FIG. 12
• FIG. 14 : Longitudinal section through a sixth embodiment of a plasma electrode
• FIG. 15 : Cross section through the plasma electrode after FIG. 14
• FIG. 16 : Longitudinal section through a seventh embodiment of a plasma electrode
• FIG. 17 : Cross section through the plasma electrode after FIG. 16
• FIG. 18 : Longitudinal section through an eighth embodiment of a plasma electrode
• FIG. 19 : Cross section through the plasma electrode after FIG. 18
• FIG. 20 : Longitudinal section through a ninth embodiment of a plasma electrode
• FIG. 21 : Cross section through the plasma electrode after FIG. 20
• FIG. 22 : Longitudinal section through a tenth embodiment of a plasma electrode
• FIG. 23 : Cross section through the plasma electrode after FIG. 22
• FIG. 24 : Longitudinal section through an eleventh embodiment of a plasma electrode
• FIG. 25 : Cross section through the plasma electrode after FIG. 24
• FIG. 26 : Longitudinal section through a twelfth embodiment of a plasma electrode
• FIG. 27 : Cross section through the plasma electrode after FIG. 26
• FIG. 28 : A schematic embodiment in section, showing a compression deformation of the centric core holder with a compression tool.
• FIG. 29 : The core holder after FIG. 28 after compression deformation
• FIG. 30 A further schematized exemplary embodiment with a core holder, on the outer circumference of which cooling channels in the form of threads are formed.

That in the FIGS. 1 to 3 illustrated principle of leadership of the cooling liquid applies to all other embodiments according to the FIGS. 4 to 30 because these are merely modifications of the principle FIGS. 1 to 3 are. Therefore, the same explanations apply to the same parts.

The in the FIGS. 1 to 3 illustrated plasma electrode 1 consists of a hollow cylindrical electrode body 2 made of a metal material, preferably a copper alloy or a silver alloy, in the interior of a hollow cylindrical cooling tube 3 is releasably attached.
The cooling tube 3 forms in its interior a coolant liquid-conducting channel 4, which is conveyed in the direction of arrow 19 to the front of the cooling tube 3 under pressure.

On the front inside of the electrode body 2, a core holder 5 is integrally formed on the bottom side, in which a -. Hafnium-based electrode core 9 e.g. is held in a press fit.

The electrode core 9 is pin-shaped, round cylindrical and in the front end face of the emission surface is formed for the plasma arc.

Important in the invention is now that in all embodiments of the part of the electrode body 2 forming core holder 5 is formed as a cone body, that is, this body is preferably round cylindrical, as determined by the circular surfaces 25 in FIG. 3 is shown schematically. It thus forms a flattened truncated cone, wherein the flattened frustoconical surface forms an end face 22.
According to FIG. 3 is placed on the outer circumference of the cone holder formed as a core holder 5, the front end side of the cooling tube 3 and thus forms an annular stopper 10 which is secured against the outer edge of the core holder 5 and held there.
The inside of the cooling tube 3 thus forms the ring stop 10 for resting on the outer surface of the conical surface 7 formed as a lateral surface of the core holder. 5

It should also be noted that the electrode core 9 is held in a secured position in a frontal bore 8 of the core holder 5.

It is important that it must be prevented in any case that the front end of the cooling tube 3 sealingly rests on the core holder 5. For this purpose, one or more, the cooling liquid recesses are provided, wherein in the embodiment of the FIGS. 1 to 5 these, the cooling liquid leading recesses are formed as mirror-symmetrical to each other opposing flats 15 formed as a truncated cone body core holder 5.

This is in FIG. 3 illustrated by drawings. It is shown that in itself the surface of the frusto-conical core holder 5 formed as a circular surface 25 is cut off on both sides so as to form the flats 15, which in turn form two mutually opposite annular gaps leading to the cooling liquid.

Through these annular gaps, the coolant brought up in the direction of arrow 19 flows parallel to the conical surface 7 through the flattenings in the direction of arrow 19 (see FIG. FIG. 3 ), is deflected at Ringnutgrund 13 of the electrode body 2, and then flows in the opposite direction of arrow 23 on the outer circumference of the cooling tube and the inner circumference of the electrode body 2 through the annular gap 18 back.

The FIG. 3 shows in this case the cut out of the circular surface 25 on both sides end face 22, in which the rear end of the electrode core 9 protrudes as an electrode core extension 11 into the cooling liquid.

In deviation from the embodiment according to FIG. 1 show the FIG. 4 in that it is also possible to mount the rear end of the electrode core 9 sunk in the material of the core holder 5, so that no electrode core projection 11 in contact with liquid, protrudes into the cooling liquid, as in FIG. 1 is shown.

From the embodiment of Figures 2 and 5 can also be found that instead of two opposite flats 15 of the core holder 5, either only one flattening 15 may be present or more than two flats, which are then preferably evenly distributed around the circumference.

Here shows the embodiment of the FIGS. 6 and 7 in that, instead of the use of flats in the cone body of the core holder 5, radially outwardly open longitudinal grooves 17 can be formed, through which the cooling liquid flows.

In the illustrated embodiment, the longitudinal grooves 17 are formed as outwardly open wedge-shaped grooves. Instead of such wedge-shaped grooves also open outwardly semicircular, elliptical or otherwise profiled grooves can be used. Also, the number of grooves is not limited. In addition to a single longitudinal groove 17, a plurality of longitudinal grooves 17 distributed uniformly on the circumference of the formed as a truncated cone core holder 5 may be arranged.

This show as a further modification of the inventive principle the FIGS. 8 and 9 , where the core holder 5 is formed star-shaped, which means that the longitudinal grooves 17 a relatively large material area of the core holder 5 aus¬ and this results in a particularly large, the cooling liquid leading annular gap 16 results.

This is also shown by the embodiment FIGS. 10 and 11 , where compared to the embodiment according to FIGS. 8 and 9 Yet another material saving with respect to the material of the core holder 5 and instead of a four-star arrangement after FIG. 9 now a five-star arrangement after FIG. 11 is provided. This results in a greatly enlarged outer surface of the core holder and optimum cooling properties. He is, so to speak, designed as a "heat sink". Such heat sinks were previously known only for convective air cooling of semiconductor devices. However, the invention proposes a liquid-cooled core holder with an optimally enlarged surface.

There are thus five evenly distributed on the circumference longitudinal grooves 17 are provided, which are suitable to distribute the effluent from the interior of the cooling tube 3 cooling liquid evenly over the outer circumference of the core holder 5 and to lead into the interior of the electrode body 2 to the Ringnutgrund 13 and there in the opposite direction (arrow 23) lead out again.

The greater the material saving in the material of the core holder 5, and the smaller the material cross section of the core holder 5, the better the cooling effect.

This means that the core holder 5 due to the greatly enlarged, radially outward surface - due to the large number of introduced longitudinal grooves 17 - has a very large cooled surface, so that a plasma electrode thus prepared a much longer service life due to the improved cooling of the electrode core. 9 has, as comparatively different, competing products.

According to the embodiments of the FIGS. 1 to 11 the longitudinal grooves 17 are preferably achieved by a machining with a milling tool or the like.

In the following embodiments, for. B. the embodiment according to FIGS. 12 and 13 , It is envisaged that instead of the longitudinal grooves 17 now drilling channels 21 are introduced with a suitable drilling tool. Also here shows the FIG. 13 in that a total of four drilling channels 21 arranged opposite one another and distributed uniformly around the circumference lead to a decisive increase in the surface area of the outer circumference of the core holder 5, so that the core holder is cooled optimally.

Of course, it is possible to combine drilling channels 21 with longitudinal grooves 17 with each other.

The FIG. 15 shows that a plurality of drill channels 21 can be introduced evenly distributed around the circumference, and the FIGS. 16 and 17 show that even essential material of the core holder 5 can be saved by this is only formed on one side and only on one side of the radial inner circumference of the cooling tube 3 secures, while the other, opposite inner circumference of the cooling tube 3 is exposed. This ensures optimal guidance of the coolant, without flow resistance.

The previously in FIG. 2 illustrated bilateral flattening now extends as it were over an angle of 270 degrees according to the embodiment FIG. 17 ,

In contrast, the embodiment according to the FIGS. 18 and 19 in that the flattening can also extend over an angle of 180 degrees so as to give an annular gap 28 extending over a circle angle of 180 degrees.

The FIGS. 20 and 21 show in deviation from the embodiment according to FIG. 2 in that, in addition to the two opposing flattenings 15, also opposing drill channels 21 can be introduced so as to ensure optimum guidance of the cooling liquid.

The end face 20 of the cooling tube 3 (s. FIG. 1 ), however, does not necessarily rest on the inside of the outer circumference of the core holder 5 designed as a truncated cone.

In another embodiment, it may be provided that this end face on assigned, annular and over the outer circumference of the core holder extending, semi-open annular grooves, so that the entire end face 20 then rests flush in the arranged on the outer circumference of the core holder 5 annular groove.

In the embodiment according to FIG. 22 is in combination of the embodiment according to FIG. 17 still shown that in one side asymmetrically formed core holder 5, an additional or more additional drilling channels 21 may be arranged.

The FIGS. 24 and 25 show that two or more drill channels 21 can be arranged in the one-sided asymmetrically designed core holder 5.

In FIGS. 26 and 27 is shown that in an asymmetric core holder and three drill channels can be arranged so that in all unilateral embodiments of the frusto-conical core holder at least one one-sided segment recess 24 is present, which extends over any circumferential angle of z. B. 60, 90, 180 or 270 degrees can extend.

Important in all embodiments is that the longitudinal axis 27 of the cooling tube 3 is held decentered in the core holder 5.

If it has been described in the previously described embodiments that the core holder 5 can also be formed on one side and asymmetrically, then it can be provided that in the opposite, exposed part of the core holder, where no conditioning of the cooling tube takes place, additional centering means are available.

In the embodiment according to FIG. 28 is shown that the deformation of a round cylindrical core holder 5 is carried out with a compression tool 29. In this non-claimed example, it is not necessary for the solution that the core holder 5 is formed as a cone body, as described in the previous embodiments. On the front side of the cylindrical core holder 5, the upsetting tool 29 is placed so that the compression head 30 engages over the upper end face 22 of the core holder 5. The punch 32 of the swaging head 30 rests on this end face 22. By a pressure impact in the direction of arrow 35 of the core holder 5 is compressed and forms a radial, diameter-increasing bead 33 according to FIG. 29 out. This bead 33 is the bearing surface for the front end side of the cooling tube. 3

It is advantageous if the upset head 30 still lateral bevels 31 are formed, which form between them rib-shaped, obliquely outwardly directed grooves. The bevels 31 deform the upper side surfaces of the core holder 5 during upsetting and thus simultaneously form radially and obliquely outwardly directed flats 15 or longitudinal grooves 17. As a result of the flattened portions 15 or longitudinal grooves 17 formed in this way during compression shaping, cooling ducts which are opened outwards are designed to guide the cooling medium over the surface of the core holder which is thus enlarged.

Instead of attaching the flats 15 or the longitudinal grooves 17 by upsetting deformation, it is provided in a development that a thread 34 is cut into the surface of the core holder or molded by a pressing tool. Again, additional cooling channels of great length are formed by the thread cut.

Thus, an embodiment discloses an enlargement of the surface of the core holder 5 by flats 15, longitudinal grooves 17 and threads 34 regardless of whether the front of the cooling tube 3 is touching on the core holder 5 or the core holder overlaps to form an annular gap 16 without contact.
By enlarging the surface of the core holder 5, a substantially improved cooling of the core holder is achieved in the immediate vicinity of the electrode core 9 heated to approximately 1000 to 2000 Celsius degrees. The service life of the electrode core 9 could be significantly improved.

drawing Legend

1.

plasma electrode

Second

electrode body

Third

cooling pipe

4th

liquid channel

5th

core holder

6. 7.

conical surface

8th.

drilling

9th

electrode core

10th

annular stop

11th

Electrode core approach

12. 13.

Ringnutgrund of 18

14. 15.

flattening

16th

annular gap

17th

longitudinal groove

18th

annular gap

19th

arrow

20th

front

21st

drill hole

22nd

Front side of 5

23rd

arrow

24th

segment recess

25th

circular area

26th

Face of 3

27th

Longitudinal axis (stop)

28th

annular gap

29th

upsetting tool

30th

Forming head

31st

slope

32nd

stamp

33rd

bead

34th

thread

35th

arrow

Claims (13)

1. A plasma electrode (1) for a plasma cutting apparatus consisting of a cylindrical cooling tube (3) and an approximately hollow-cylindrical electrode body (2), at whose front side a central core holder (5) arranged at the end face and facing into the interior of the electrode body (2) is arranged for holding an emitting electrode core (8), wherein the cooling tube (3) through which an axial cooling liquid flow flows in operation is arranged in the interior of the electrode body (2), wherein the cooling tube (3) is releasably connected to the rear end of the electrode body (2) by means of a connection preferably formed as a screw or plug connection, characterized in that the core holder (5) is formed as a conical body facing into the interior of the electrode body (2), whose conical surfaces (7) taper in the axial direction starting from the base of the electrode body (2), and the cooling tube (3), with its front end face (20), is set on the core holder (5) in an at least partially positionally secured manner.
2. The plasma electrode according to claim 1, characterized in that ribs or grooves or holes or threads are formed into the surface of the core holder (5), which enlarge the cooled surface of the core holder (5).
3. The plasma electrode according to claim 1, characterized in that at least one recess (16, 17, 21, 24) conducting the cooling liquid is arranged in the core holder (5).
4. The plasma electrode according to claim 3, characterized in that the recess (16, 17, 21, 24) arranged in the core holder (5) redirects the cooling liquid conducted in the interior of the cooling tube (3) from the interior of the cooling tube (3) into the outer annular space (18) between the outer surface of the cooling tube and the inner surface of the electrode body (2).
5. The plasma electrode according to any one of claims 1 to 4, characterized in that a recess arranged in the core holder (5) is formed as an at least one-sided, axially aligned, liquid-conducting flattened portion (15).
6. The plasma electrode according to any one of claims 3 to 5, characterized in that the recess (16, 17, 21, 24) arranged in the core holder (5) is arranged parallel to the conical surface (7) of the conical core holder (5).
7. The plasma electrode according to any one of claims 3 to 6, characterized in that the recess (16, 17, 21, 24) arranged in the core holder (5) is formed as a semi-open longitudinal groove (17) or as a semi-open bored channel (18) or as a cut-out segment (24) open radially toward the outside.
8. The plasma electrode according to any one of claims 4 to 7, characterized in that a plurality of recesses (16, 17, 21, 24) conducting the cooling liquid are arranged equally spaced about the circumference of the core holder (5).
9. The plasma electrode according to any one of claims 1 to 8, characterized in that the end face (22) of the core holder (5) facing into the interior of the cooling tube is flattened and the rear end face of the electrode core (9) is flush with this end face (22).
10. The plasma electrode according to any one of claims 1 to 8, characterized in that the end face (22) of the core holder (5) facing into the interior of the cooling tube (3) is flattened and the electrode core (9) protrudes into the interior of the cooling tube (3) with an extended projection (11).
11. The plasma electrode according to any one of claims 1 to 10, characterized in that the cooling tube (3) has lateral slots or lateral holes at its front surface facing the core holder (5).
12. The plasma electrode according to any one of claims 1 to 11, characterized in that the core holder (5) is formed as a truncated cone flattened at least on one side.
13. The plasma electrode (1) according to claim 12, characterized in that the core holder (5) has a two-sided flattened portion formed in a mirror-symmetrical manner with respect to the longitudinal central axis of the core holder (5) formed as a truncated cone.

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