EP2941493B1 - Apparatus for thermally coating a surface - Google Patents

Description

The present invention relates to a device for thermally coating a surface having the features of the preamble of claim 1.

The WO98 / 35760 A1 discloses a burner head rotatable within a bore to be coated, from which a spray jet emerges perpendicular to the longitudinal axis. Next thematizes the WO98 / 35760 A1 the negative effects of adhering to the burner head spray particles. This will be done according to the WO98 / 35760 A1 thereby prevents the metal wire and the nozzle are at the same electrical potential, so that an accumulation of metal dust is avoided.

The DE 10 2009 023 603 A1 deals with a suction device for extracting waste particles during thermal coating of an inner surface to be coated at least one bore in a component. The suction device has at least one suction tube, which can be arranged below the bore. It is paid attention to a certain distance. It is also disclosed that an inner surface of the suction tube is polished smooth and / or coated with a non-stick coating.

The DE 10 2006 230483 A1 deals with a device for cold gas spraying, in which gas and spray particles are accelerated. The cold gas spray nozzle is at least partially coated on its inner wall in order to use so hotter gases and spray particles than before. The coating should prevent caking of the hot spray particles on the nozzle inner wall.

From the JP61-245978 A is a ceramic-coated burner nozzle for inert gas welding known. The ceramic coating is applied by means of plasma flame spraying. The ceramic coating is then ground to avoid adhesion of weld spatter.

The WO 2008/125356 A1 deals with an expansion nozzle, which has a convergent and a divergent and an intermediate narrowest area. The inner contour of the expansion nozzle may be subjected to a surface treatment such as polishing and / or coating.

In the US 3,055,591 a spray gun is disclosed. A front end of the nozzle is designed in the manner of a reflector, and equipped with a polished reflection surface for radiant heat. Thus, it is to be achieved that the heat generated at the tip of the melting wire strikes the reflecting surface and is reflected correspondingly back to the molten particles and to the wire tip.

Devices for thermally coating a surface are disclosed, for example, in U.S. Pat US 6,372,298 B1 , of the US 6,706,993 B1 and the WO2010 / 112567 A1 described. The devices mentioned there together have: a wire feed device for feeding a consumable wire, the wire acting as an electrode; a source of plasma gas for generating a plasma gas stream; a nozzle body having a nozzle opening through which the plasma gas stream is passed as a plasma jet to a wire end; and a second electrode disposed in the plasma gas stream prior to entering the nozzle orifice. Also the US Pat. No. 6,610,959 B2 and the WO2012 / 95371 A1 deal with such devices.

Between the two electrodes forms an arc through the nozzle opening. The plasma jet emerging from the nozzle opening strikes the end of the wire, where it causes the wire to melt off with the arc and to remove the molten wire material in the direction of the surface to be coated. Secondary air jets are provided around the nozzle orifice to form a secondary gas jet which strikes the material melted from the wire end to effect an acceleration of transport toward the surface to be coated and a secondary atomization of the molten wire material.

Today's internal combustion engines or their engine blocks can be made of a metal or light metal, such. Cast aluminum, in particular aluminum blocks have on their cylinder bores an iron or metal layer. The metal layer may be thermally sprayed. As thermal spraying processes, in addition to two-wire arc spraying (TWA), HVOF spraying and plasma powder spraying, the above-mentioned processes are known as plasma wire spraying or PTWA (Plasma Transferred Wire Arc). A coating of the cylinder bores by means of the plasma wire spraying method, ie with the PTWA is advantageous because it is possible to produce a coating which has a positive effect on a reduced wear factor, on an extended service life of the engine with lower oil consumption compared to conventional linings by means of cast bushes made of cast iron material.

However, the known devices for thermal coating and the processes carried out with them harbor some disadvantages. The known devices are retracted, for example, in a cylinder bore to be coated and rotate in operation with a simultaneous linear up and down movement around itself. It is apparent that during the rotation of the device, the flowing in the cylinder bore process gases through flat surfaces of the device, in particular be taken similar by flat surfaces of the housing, a blade effect, so that additional turbulence arise.

For higher wire feed rates correspondingly higher currents are required, which simultaneously cause a higher thermal load of the devices. Due to the heat input of the plasma and the liquid spray particles, the surface of the bore is strongly heated and there are very high surface temperatures. By the flowing out of the bore, heated process gases, the devices are additionally heated. In addition to the high working temperatures, the spray dusts and overspray particles pose a problem for the long-term safe operation of the burner.

Not all liquid spray particles adhere to the surface, the order efficiency in the hole is about 87%, thus resulting in correspondingly higher wire feed rates of example 10 kg / h very high amounts of dust. These spray dusts are hot, doughy particles, which are deflected by the flowing process gases in the bore of the (aluminum) surface or of the spray coatings already formed. These particles can then lead to deposition on the surface of the device, in particular on its housing, which can grow to thick coverings with increasing injection time and then flake uncontrollably as larger pieces and then possibly embed in the functional coating or to a short circuit can lead the device. This short circuit can occur as soon as a closed electrically conductive coating has formed on the outer surface of the device.

Also, the known devices have such a dimension that they can no longer coat the smaller and smaller in diameter cylinder bores with the required, promising parameters.

In order to protect the devices from the adhesion of said particles, it is known to provide the devices with a removable plastic and / or rubber jacket. However, this is very clumsy aufgestreifbar and all the more complicated removable. Removal of Kunstsoff- and / or rubber sheath is required at the latest for maintenance purposes of the device. Also, the effective size is significantly increased by the plastic and / or rubber jacket, which is not conducive to a required coating result .. In addition, the plastic sheath will be worn after a certain period of operation due to the effects of the returned hot particles, and will need to be replaced. This is not only time consuming, but also costly.

Against this background, the present invention has the object to provide an improved device for thermal coating of surfaces, with which the injection process even small bore diameter is process stable feasible.

This object is achieved by a device having the features of claim 1. Further, particularly advantageous embodiments of the invention disclose the dependent claims.

It should be noted that the features listed individually in the following description can be combined with one another in any technically meaningful manner and show further embodiments of the invention. The description additionally characterizes and specifies the invention, in particular in connection with the figures.

The device for thermally coating a surface is designed as a rotating, single-wire injection device and rotatable about its axis. The device has at least one housing, a cathode, an anode, which is designed as a consumable wire, and at least one preferably electrically and thermally acting insulating element. According to the invention, at least the housing has a non-stick and insulating layer system, wherein a non-releasable non-stick surface is arranged on an electrically and thermally insulating layer, which is arranged on the housing.

The device, also referred to as a burner or burner head, is mounted by a spindle to a suitable rotating device. The rotary device comprises in addition to the rotary drive and the rotary feedthrough of the process gases (primary gas / secondary gas) and the contacting of the cathode and anode potential.

The spindle thus serves as a kind of spacer / extension element from the rotary device to the burner head. The spindle carries the process gases (primary gas / secondary gas), the wire and the electrical energy to the device, with the cathode potential lying on the spindle housing.

The housing of the burner head can be made in one or more parts, preferably in two parts, with at least one main element and at least one cover element which can be screwed together.

The features listed individually in the following description can also be applied to the spindle housing in any technically sensible manner in addition to the burner head housing or be combined with one another on these housings or partially or completely relate to these cases and show further embodiments of the invention.

The housing may be made of copper, a copper alloy, in particular brass or aluminum or an aluminum alloy, the materials are of course not intended to be limiting. Nevertheless, the materials mentioned within the meaning of the invention are metallic materials. In a preferred embodiment, the housing is formed of brass because of the extremely advantageous in the operation of the device advantageous properties such as thermal expansion, heat capacity, thermal conductivity and surface quality.

To reduce or avoid the adhesion of overspray and / or spray dust on the entire device, the adhesive mechanisms of the deflected / reflected particles depending on the spray additive used, ie the wire material, to pay attention. The high temperatures can lead to localized welds, and the molten state can cause some particles to mechanically bond when they impact the device's surfaces. By way of example, the use of non-magnetizable materials avoids the adhesion of magnetized deflected or reflected particles.

In addition to the housing material, in particular the surface quality is crucial for the avoidable adherence of overspray and / or sprayed dust, which is why the surface is preferably polished in order to reduce the roughness, which counteracts deposition on the housing.

The following described embodiment of a non-stick surface formed by a single layer is not included within the scope of the invention. A non-stick surface may be a surface of a suitable housing and / or spindle material which has at least non-stick properties for the expected spray dusts whose roughness can be further reduced by suitable surface finishing, for example by grinding, superfinishing, polishing or lapping. The housing may also have as a non-stick surface but also a suitable coating, which on the housing is applied. The non-stick surface is materially connected, ie not detachably connected to the housing, which means that either the material of the housing itself forms the non-stick surface, or that the non-stick surface is applied as a protective layer on the material of the housing, so that the two components (housing / spindle Anti-adhesive surface) are in any case not non-destructively separable. The non-stick surface may also have electrically and thermally insulating protective functions. To improve handling and to protect the achieved surface quality, a high hardness of the housing material is expedient or can be increased by the targeted selection of the coating material of the housing, the hardness of the non-stick surface.

For example, the housing as a non-stick surface may have a decorative or hard chrome coating. For the purposes of the invention, the decorative or hard chrome coating is a metallic non-stick surface, and can have, for example, a layer thickness of 0.5 μm or 40 μm-100 μm. After appropriate surface finishing, the spray dusts do not bond firmly with these coatings. Rather, depositing sprayed dust can hang up only loosely.

Generally, for the possible embodiment of the non-stick surfaces, by different coating methods of the housing, known metallic hard materials (eg tungsten carbide, titanium carbide, titanium nitride) or hard material mixed crystals (eg tungsten carbide titanium carbide, tungsten carbide cobalt, titanium carbide titanium nitride) or non-metallic hard materials (eg diamond , Silicon carbide and nitride, boron carbide and nitride, chromium oxide), which can be applied by different methods (eg electroplating, thermal spraying, PVD, CVD), also with the formation of intermediate layers.

In a possible embodiment, the housing may have an aluminum oxide protective layer as the non-stick surface. The alumina protective layer is a ceramic non-stick surface. This can be applied by way of example by a powder plasma spraying. In this case, for example, an example 500 .mu.m - 1000 .mu.m thick aluminum oxide protective layer can be applied as an additional electrically insulating layer. After coating, the non-stick surface can be sealed by silicates such as water glass in the hot state to the sprayed possibly canceling hygroscopic property of the alumina protective layer, which could lose the electrical breakdown strength at high humidity. Subsequently, it can further be provided that the sprayed-on aluminum oxide protective layer can be ground and / or polished in order to counteract any possible adhesion to a rough surface. The electrical insulation process reliability is increased, since in this way the cathode potential of the housing is additionally advantageously isolated and thus also further design options of the aforementioned isolation element are permitted, as will be discussed in more detail later.

In a further possible embodiment, the housing may have as an anti-adhesion surface an aluminum layer, which may be applied by way of example by a wire arc spraying, wherein the aluminum layer may have a thickness of for example 100 .mu.m. This layer can subsequently be converted by the MAO (Micro-Arc Oxidation) or PEO (Plasma Electrolytic Oxidation) process into an aluminum oxide protective layer, for example into an Al ₂ O ₃ ceramic layer, which is electrically insulating and additionally adheres to sprayed dust prevents simultaneous heat protection.

As already mentioned, the housing may also be formed of a heat-resistant aluminum material instead of the brass. This is advantageous in that the thermal conductivity is significantly increased compared to brass, so that the flowing process gases can cool the housing inside better. However, in order for the radiation and convection heat on the other hand can not get over the surface of the spindle and the burner so quickly into the interior of the components, can be applied as an anti-adhesion surface outside, for example, an oxide ceramic coating, for example by powder plasma spraying. Alternatively, an electrically insulating coating, for example by the so-called. MAO (Micro-Arc Oxidation) or eg the PEO (Plasma Electrolytic Oxidation) method with a 50 .mu.m thick titanium oxide thermal barrier coating are applied. Subsequently, these non-stick surfaces can be ground and polished.

In a further possible embodiment, the housing and / or the spindle may have a zirconium oxide protective layer as a non-stick surface. The zirconia protective layer has, in addition to the non-stick property, a heat-insulating property, so that the housing is protected against heat convection and heat radiation, so that at the same time further reduces the possible adhesion of sprayed dust on the preferably ground and / or polished non-stick surface.

In still further possible embodiment, the housing may have an aluminum nitride protective layer as a non-stick surface. Due to the advantageous properties of high thermal conductivity with good electrical insulation, high temperature resistance and high hardness of aluminum nitride, the reflected and / or deflected particles, which impinge on the non-stick surface, the heat quickly removed, so that the particles solidify, without local defects to cause the aluminum nitride. A mechanical clamping of the particles is avoided by the surface texture. Local destruction is avoided in particular by the use of a nitride for the coating of the housing. In this way, the non-stick surface can not be permanently damaged.

Particularly in order to increase process reliability, it is expedient for the purposes of the invention to form the non-stick surface on a layer system of different materials, the non-stick surface being produced on the outermost layer by suitable surface finishing. Thus, the different special properties of the respective coating materials can be combined in a technically meaningful way.

For example, a 500 .mu.m.-1000 .mu.m thick aluminum oxide protective layer can be applied to the housing by means of powder plasma spraying, onto which, for example, a further 100 μm-200% .mu.m thick tungsten carbide-cobalt covering layer is applied by another powder plasma spraying. In this case, an additional electrically and thermally acting insulation is created by the aluminum oxide protective layer and by the high thermal conductivity and high temperature resistance the tungsten carbide-cobalt topcoat created the non-stick surface in the subsequent surface finish.

Of course, the additional electrically and thermally acting insulation can also be achieved by other materials, for example zirconium oxide or aluminum oxide-zirconium oxide mixtures. Instead of the exemplary tungsten carbide-cobalt covering layer, other materials, for example chromium oxide, can also be used to form the non-stick surface. Diamond, silica, and especially silicon carbide coatings, which are deposited as thin films on the already surface-treated protective layer by suitable methods (e.g., PVD, CVD) and which subsequently form suitable surface finishes, have also been found to be advantageous.

In a preferred embodiment, the housing is designed predominantly round. Only in the area of the nozzle opening, that is to say only on the side of a nozzle ring and only in the region of the nozzle ring is the circular design of the housing seen in cross-section eliminated. Here, the housing is flattened, wherein an oblique transition merges into a plane in which the nozzle ring or the nozzle opening is arranged. The consistent maintenance of the circular in cross-section housing avoids a blade effect, ie entrainment of the located in a cylinder bore process gases or air, whereby a negative influence of the blade effect on the, in the direction of the surface to be coated particles to be transported is significantly reduced. This flow-optimized surface shape also affects reduced deposits on the housing and also favors the subsequent surface finishing to form the non-stick surface.

It is expedient if the at least one insulation element is designed, for example, as a nozzle ring.

The nozzle ring is preferably formed of a ceramic, more preferably of a high-performance ceramic and acts electrically and thermally insulating between the housing and a wire guide. The nozzle ring is the only external insulator in the otherwise metallic outer shape of the entire device or the Housing. The function of the nozzle ring can also be performed as an extension of a secondary gas nozzle.

In a possible embodiment, the nozzle ring is funnel-shaped and extends from an outer ring in the direction of a central opening. It is also possible to perform the nozzle ring sleeve-like with a projecting away from a Fußflansch wall portion. It is also possible to provide a funnel-shaped section on which a wall section extending away from it is arranged. The nozzle ring may be one-piece or multi-piece, preferably ceramics such as e.g. Silicon nitride, aluminum nitride, boron nitride, zirconium oxide, aluminum oxide, ATZ or ZTA can be used for producing the nozzle ring. In a preferred embodiment, the nozzle ring is polished at least on its surface oriented away from the cathode, more preferably highly polished, in order to avoid buildup.

Surprisingly, it has been found that, in particular through the use of aluminum nitride, good results are achieved in order to avoid and / or remove reflected and / or deflected particles. Due to the particularly high thermal conductivity and the relatively high temperature resistance of aluminum nitride, the reflected and / or deflected particles, which impinge on the polished nozzle ring surface, the heat quickly withdrawn, so that the particles solidify without causing local defects on the aluminum nitride. A mechanical clamping of the particles is avoided by the surface texture.

Another ceramic material for the nozzle ring with very high thermal conductivity and high dielectric strength is the composite ceramic Shapal ™.

With the invention, the effect of better heat dissipation and thus faster solidification of the spatter is achieved with smaller splashes before they destroy the surface texture of the ceramic by local overheating and thus a local clamping of the particles is made possible.

In order to avoid buildup on the nozzle ring, several additional measures can be provided:
The nozzle ring is designed in several parts and has partially inside a non-stick and / or insulating layer.

The nozzle ring is made in one piece and has partially inside and outside on a non-stick and / or insulating layer.

The nozzle ring is multi-part and has an extended configuration.

The nozzle ring is in one piece and has a prolonged configuration.

The nozzle ring is made in one piece as a protective gas nozzle with holes in the middle in one plane.

The nozzle ring is in one piece as a protective gas nozzle with holes tangential in one plane.

The nozzle ring is in one piece as a protective gas nozzle with holes tangentially in several levels.

The nozzle ring is in one piece as a protective gas nozzle with slot and holes tangentially in several levels.

The nozzle ring is in several parts as a protective gas nozzle with slot and tangential labyrinth holes.

Advantageously, a protective gas flow is introduced in order to avoid and / or remove reflected and / or deflected particles, wherein the protective gas flow around the spray jet is generated continuously and / or pulsed. To generate the protective gas flow, the process gases can be used, wherein in particular the secondary gas can be supplied as a protective gas. It is also possible to supply gases other than process gases, such as Air, argon or other gases. The protective gas flow can be effected by means of bores arranged centrally and / or bores arranged tangentially in one or more planes of the nozzle ring. Furthermore, to stabilize the protective gas flow, the flow through slot nozzles and / or slot nozzles with centrally and / or tangentially arranged holes in one or more planes of the nozzle ring. Furthermore, this can be done by slot nozzles with labyrinth with centrally arranged holes / slots and / or tangentially arranged holes / slots to stabilize the protective gas flow.

In the aforementioned formation of the non-stick surface on an additionally electrically insulating layer or an additionally electrically insulating layer system of the housing, the functions of the nozzle ring in these special cases can also be taken over by the secondary nozzle and the electrically insulating housing.

If necessary, the devices having the non-stick surface are cleaned. After the coating or in part also during the coating of the component to be coated, the burner head and the spindle can be blown off with a linear and rotating movement in front of an air nozzle, so that, for example, electrostatically adhering dusts can be removed from the housings. Of course, the device for removing any adhering dusts, even before a fan nozzle rotating or linearly moved by an annular air nozzle. For blowing off the device not only air, preferably compressed air can be used. It is possible to clean the device with carbon dioxide (similar to snow blasting), nitrogen and / or argon. A mechanical cleaning, for example by brushing, of course, with appropriate design of the non-stick surface can also be implemented. Dust generated during the cleaning process can be supplied to the filters for disposal via the existing suction devices.

With this blowing is additionally achieved that the burner head and / or the spindle are cooled during the cleaning process. Thus, even with smaller holes of less than eg 60 mm, a reliable, ie process-stable coating process can be achieved, since the device,

in particular their housing is additionally cooled specifically before a renewed coating process is performed.

In addition, especially the ceramic nozzles, or preferably the nozzle ring, freed from dust residues, for which example is blown with an annular air nozzle against the ceramic nozzles. In order to prevent the penetration of dust into the interior of the housing, the process gases flow through the nozzle openings during the cleaning operations, including during the cleaning of the burner head housing, with possibly different parameters. Alternatively, the nozzle orifice could be exemplified with a sealing element, e.g. closed with a rubber stopper of only 2 mm diameter, for example. The sealing element is of course adapted to the nozzle opening to prevent penetration of spray dust or other harmful media.

It can be achieved if the cleaning device is arranged on the carrier module (that is, on a robot arm, for example), which has the surface to be coated, that is, e.g. carries the engine block with the cylinder liners to be coated. In this case, the device can be moved out of the coated bore. The carrier module moves with its cleaning device, so preferably with its blower along the device up and down, with the device rotates at low speed. It may be auseichend if the device is already cleaned after a revolution, which of course several revolutions around its own axis are possible.

The invention provides a device for coating surfaces, in particular for lining cylinder bores with small diameters (<60 mm) of internal combustion engines, which is rotatable about its axis and, in the case of a melting-down wire system designed as an anode, a high application rate with a long service life and correspondingly reduced maintenance costs can be process-stable even small bore diameter inside coating (rotating single-wire arc spraying). Of course, not only solid wires, but also cored wires can be melted off. The necessary for reliable operation electrical and thermal insulation are within the otherwise metallic outer casing (also the preferred Brass is referred to as metallic in the context of the invention) of the entire device. Only in the area of the particle jet outlet are electrical and thermal insulation used.

Fig. 1

eine Explosionsdarstellung einer Vorrichtung zum thermischen Beschichten einer Oberfläche,

Fig.1a

eine Schnittdarstellung durch eine Vorrichtung nach Figur 1,

Fig. 2

einen Düsenring als Einzelheit, in erster Ausgestaltung

Fig. 3

einen Düsenring als Einzelheit, in zweiter Ausgestaltung

Fig. 4 bis Fig. 6

mögliche Ausgestaltungen für eine Antihaftoberfläche des Düsenrings, und

Fig. 7 bis Fig. 11

mögliche Ausführungen für eine Schutzgasströmung.

Further advantageous details and effects of the invention are explained in more detail below with reference to exemplary embodiments illustrated in the figures. Show it:

Fig. 1

an exploded view of an apparatus for thermally coating a surface,

1a

a sectional view through a device according to FIG. 1 .

Fig. 2

a nozzle ring as a detail, in the first embodiment

Fig. 3

a nozzle ring as a detail, in the second embodiment

Fig. 4 to Fig. 6

possible embodiments for a non-stick surface of the nozzle ring, and

Fig. 7 to Fig. 11

possible designs for a protective gas flow.

In the different figures, the same parts are always provided with the same reference numerals, so that these are usually described only once. In the Figures 2 and 3 the local components are each shown in perspective from both sides, ie from a bottom and from an upper side. In the FIGS. 7 to 11 In each case a cross section and a plan view are shown.

FIG. 1 shows a device 1 for thermally coating a surface. The device 1 may also be referred to as a burner 1, which for the thermal coating of a cylinder bore even smaller diameter of less than 60mm is suitable. For this purpose, in the device 1, an arc is ignited, which melts the spray additive, wherein molten material is transported to the surface to be coated. For this purpose, two gases are used namely primary gas and secondary gas. The primary gas has the task of maintaining or carrying the arc, wherein the primary gas additionally has cooling functions, the secondary gas also has a dual function. On the one hand, the secondary gas should support the transport of the molten particles and further atomize and accelerate the particles. On the other hand, the secondary gas has a cooling function, which will be discussed later. The primary gas may be argon, nitrogen, a mixture of inert gases or a mixture of the exemplary gases with hydrogen and / or helium. The secondary gas may be air or compressed air. It is also possible that argon, nitrogen or other inert gases are used as secondary gas. Of course, the gases exemplified are not intended to be limiting.

The device 1 may comprise a head part 2, by way of example a connector 3 as an intermediate part and an adapter 4 as a connecting part, wherein primary gas connections, secondary gas connections, power source connections, control and monitoring devices and a wire in FIG. 1 not shown. To coat a cylinder bore, the device rotates around itself and is linearly reciprocated. Of course, instead of the linear movement of the device, a linear movement of the component to be coated can take place. The same applies, of course, also for the rotational movement, if appropriate.

The device 1 for thermally coating a surface comprises, as shown by way of example, a two-part housing 6 with a main element 7 and a cover element 8, a cathode 9, a primary gas distributor 11, a secondary gas distributor 12, electrically and thermally acting insulation elements 13, 14, and 16, and an anode which is formed as a melting wire via a wire guide into a secondary gas 19, wherein a primary gas nozzle 21 is mounted centered parallel to the secondary gas distributor 12 to the primary gas distributor 11, and at its to the secondary gas 19th oriented side 22 in a plane radially arranged openings, that has holes or slots.

It is expedient if the insulation elements are embodied by way of example by a plurality of components as a nozzle ring 13, a nozzle insulator 14 and a main insulator 16.

The nozzle ring 13 is formed of a ceramic, preferably of a high-performance ceramic and acts electrically and thermally insulating between the housing 6 and the wire guide. The nozzle ring 13 is the only outer insulator in the otherwise metallic outer shape of the entire device or of the housing 6.

In a possible embodiment, the nozzle ring 13 is funnel-shaped and extends from an outer ring 24 in the direction of a central opening 25 (FIG. FIG. 2 ). It is also possible, the nozzle ring 13 sleeve-like ( FIG. 3 ) with a projecting away from a foot flange 26 wall portion 27, so that a nozzle ring 13 is formed in an extended configuration.

In a preferred embodiment, the nozzle ring 13 is polished in both embodiments, at least on its away from the cathode 9 outer surface 28, preferably highly polished to avoid buildup. The nozzle ring 13 may be one-piece or multi-piece, preferably ceramics such as. Silicon nitride, aluminum nitride, boron nitride, zirconium oxide, aluminum oxide, ATZ or ZTA can be used for producing the nozzle ring.

In order to avoid buildup on the nozzle ring 13 several measures can be provided:
The nozzle ring 13 is designed in several parts and has partially inside a non-stick and / or insulating surface or layer 29 ( FIG. 4 ).

The nozzle ring 13 is made in one piece and has partially on the inside and outside of a non-stick and / or insulating surface or layer 29.

The nozzle ring 13 is multi-part and has an extended configuration ( FIG. 5 ).

The nozzle ring 13 is in one piece and has an extended configuration (FIG. FIG. 6 ).

The nozzle ring 13 is designed in one piece as a protective gas nozzle with holes 30 in the middle in a plane ( FIG. 7 ).

The nozzle ring 13 is in one piece as a protective gas nozzle with holes 30 tangentially in a plane ( FIG. 8 ).

The nozzle ring 13 is in one piece as a protective gas nozzle with holes 30 tangentially in several planes ( FIG. 9 ).

The nozzle ring 13 is in one piece as a protective gas nozzle with slot 31 and holes 30 tangentially in several levels ( FIG. 10 ).

The nozzle ring 13 is in several parts as a protective gas nozzle with slot 31 and tangential labyrinth bores 32 (FIG. FIG. 11 ).

Advantageously, a protective gas flow is introduced into the nozzle opening 33 in order to avoid and / or remove reflected and / or deflected particles, wherein the protective gas flow around the spray jet is generated continuously and / or pulsed. The nozzle opening 33 is arranged in the flattened part of the housing 6, so its main element 7 and is also defined by the surface 28 of the nozzle ring 13. The spray jet emerges from the nozzle opening 33. To generate the protective gas flow, the process gases can be used, which only need to be branched off, wherein in particular the secondary gas can be supplied as a protective gas. It is also possible to supply gases other than process gases, such as, for example, air, argon or other gases. The protective gas flow can take place through centrally disposed bores 30 and / or tangentially arranged bores 30 in one or more planes of the nozzle ring 13. Furthermore, to stabilize the protective gas flow, the flow through slot nozzles 31 and / or slot nozzles 31 with centrally and / or tangentially arranged holes 30 in a or multiple levels of the nozzle ring 13 done. Furthermore, to stabilize the protective gas flow, these can be done through slot nozzles 31 with labyrinth 32 with bores / slots 30/31 arranged centrally and / or tangentially arranged bores / slots 30/31. The protective gas effectively acts as a protective shield to protect the surface 28, which protects the surface 28 of the nozzle ring 13, ie, the nozzle opening 33, from deposition of said particles.

As already mentioned, the housing 6 is designed, for example, in two parts with the main element 7 and the cover element 8, which benefits the ease of maintenance. As can be seen, the housing 6 is designed predominantly round. Only in the area of the nozzle opening 33, the circular design of the housing 6, ie of the main element 7, is circular as seen in cross-section. Here, the housing 6 is flattened, wherein an oblique transition merges into a plane in which the nozzle ring 13 and the nozzle opening 33 is arranged. The consistent maintenance of the circular in the cross-section housing 6 avoids a blade effect, ie entrainment of the located in a cylinder bore process gases or air, whereby a negative influence of the blade effect on the, in the direction of the surface to be coated particles to be transported is significantly reduced. This flow-optimized surface shape also affects reduced deposits on the housing.

The cover element 8 can be screwed to the main element 7 to the housing 6 by means of screws 34.

The housing 6 is preferably formed from a brass, and has a non-stick surface 36. The non-stick surface 36 may be configured so that the material of the housing 6 is polished to reduce the roughness, which counteracts deposition on the housing 6. The same applies to the spindle, not shown in the figures. The housing 6 may also have a coating of metallic or preferably ceramic type as the non-stick surface 36. At the in FIG. 1a In the embodiment shown, the non-stick surface 36 is applied by way of example as a coating. In FIG. 1a For example, a non-stick surface 36 of the main element 7 can be seen, wherein a nozzle ring is not recognizable.

Of course, the lid member 8 may have a non-stick surface.

The invention provides a rotating single-wire injection device 1, with which cylinder bores of smaller diameter can also be coated. The arc to be ignited ignites directly between the cathode and anode, ie on the wire, and not as known devices between cathode and plasma gas nozzle, in which especially at higher currents by the influence of the arc, the life was reduced. In the invention, the primary gas nozzle 21 is cooled by the secondary gas, which is why the openings, so slots are provided. With the components nozzle insulator 14, nozzle ring 13, secondary gas 19, primary gas distributor 11 and secondary gas distributor 12, which are preferably formed of a ceramic, it is advantageous to provide a quasi thermal and electrical inner insulation. The nozzle ring 13 is virtually the only external insulator in the otherwise metallic outer shape of the entire device or of the housing. The wire guide is completely incorporated with its components within the housing 6, so in the main element 7, so that external protection measures can be omitted. In FIG. 1 are still sealing elements 35 recognizable.

LIST OF REFERENCE NUMBERS

1

Device for thermal coating

2

headboard

3

Interconnects

4

adapter

6

casing

7

main element

8th

cover element

9

cathode

11

Primary gas distributor

12

Secondary gas distributor

13

nozzle ring

14

nozzle insulator

16

main isolator

19

secondary gas

21

primary gas

22

To 19 oriented page 11

24

outer ring

25

Central opening

26

base flange

27

wall section

28

outer surface

29

Non-stick and / or insulating layer

30

drilling

31

slot

32

labyrinth holes

33

nozzle opening

34

screw

35

sealing elements

36

Non-stick surface

Claims (3)

1. Device for thermally coating a surface, wherein the device is designed as a rotating single-wire spraying device (1) and is rotatable about its axis, and which has at least one housing (6), a cathode (9), an anode, which is designed as a consumable wire and at least one insulation element (13),
   characterized in that
   at least the housing (6) has an anti-adhesion and insulating layer system, wherein a non-detachable anti-adhesion surface (36) is arranged on an electrically and thermally insulating layer which is arranged on the housing (6).
2. Device according to Claim 1,
   characterized in that
   the insulation element (13) is embodied as a nozzle ring, which is formed from a ceramic material, which is polished at its surface oriented away from the cathode (9).
3. Device according to Claim 1 or 2,
   characterized in that
   the insulation element (13) at least partially has an anti-adhesion and/or insulating surface (29).

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