DE102021118093A1 - Powder injector holder and plasma torch to create a thermal spray coating - Google Patents

Abstract

The invention relates to a powder injector holder (10), comprising a base body (14) for arrangement in the area of a plasma nozzle (16) of a plasma torch (18), the base body (14) having at least one first receptacle (20a) for holding a first powder injector (22a ) and a second receptacle (20b) for holding a second powder injector (20b). The invention also relates to a plasma torch (18) for producing a thermal spray coating from at least two spray powders.

Description

The invention relates to a powder injector holder and a plasma torch for producing a thermally sprayed layer with such a powder injector holder.

Thermal spraying refers to surface coating processes in which, in some embodiments, specific spray powders are metered into a plasma jet via a powder tube or a powder injector. The spray powder is partially melted or melted in the plasma jet, accelerated in the form of spray particles and thrown onto the surface of the component to be coated. The component surface is coated by the spray particles, but not melted and not or only slightly thermally stressed. The coating properties are influenced by the temperature and the speed of the spray particles when they hit the surface to be coated.

There are standard powder injector holders for plasma torches, to which powder injectors can be attached. However, the structure of the common powder injector holder is very complicated and expensive if more than one spray powder is to be processed.

The object of the present invention is to create a powder injector holder of the type mentioned at the outset, which has a simple structure and can be flexibly equipped with at least two powder injectors. A further object of the invention is to provide a plasma torch with such a powder injector holder for producing a thermally sprayed layer.

The objects are achieved according to the invention by a powder injector holder having the features of patent claim 1 and by a plasma torch according to patent claim 8 with such a powder injector holder for producing a thermal spray layer. Advantageous configurations with expedient developments of the invention are specified in the respective dependent claims, advantageous configurations of the first aspect of the invention being to be regarded as advantageous configurations of the second aspect of the invention.

A first aspect of the invention relates to a powder injector holder, which comprises a base body for arrangement in the area of a plasma nozzle of a plasma torch, the base body having at least a first receptacle for holding a first powder injector and a second receptacle for holding a second powder injector. The powder injector holder according to the invention thus has a structurally particularly simple, cost-effective and flexible structure. In the simplest configuration, the base body can be formed in one piece. At least two powder injectors, in particular standard powder injectors, can be mounted in the receptacles, so that at least two identical or two different spray powders can be used to produce thermal spray layers. An adaptation of the receptacles and/or the base body to different plasma torches is easily possible by means of slight structural changes. Additional special cleaning, adjustment, cooling or blow-off devices on the powder injector holder or on the associated plasma torch are not necessary and can be omitted. It can also be provided that the base body or the entire powder injector holder has exactly two receptacles for exactly two powder injectors. The reduction to two powder lines significantly reduces the technical complexity, eliminates possible sources of error and thus increases process stability. In addition, set-up and maintenance costs are significantly reduced. In addition, it is basically possible to mount straight or curved powder injectors. Provision can furthermore be made for the first and/or the second receptacle to be arranged perpendicularly or at an angle with respect to a central axis of the plasma flame when the powder injector holder is mounted on the plasma torch as intended.

In an advantageous embodiment of the invention, it is provided that the first receptacle is spaced axially from the second receptacle with respect to a main axis of the base body and/or that the first receptacle and the second receptacle have a radial offset relative to one another with respect to the main axis. With the help of the known powder injector holders, it is often not possible to produce sprayed layers from two possibly different spray powders in a process-stable manner and in accordance with the specifications. Extensive tests have shown that spray powders with different properties that are metered into the plasma jet at axially and/or radially identical positions show instabilities and displacement effects that make it impossible to apply the desired coating in a process-stable and specification-compliant manner. An important reason for this behavior is the different physical properties of the spray powders, such as different densities, melting temperatures and temperature resistance. Because the first and second receptacles are spaced apart axially and/or radially, the spray powders can be metered into different zones of the plasma jet and thus different temperatures are introduced. About the respective axial distance between the first and the second recording or on the Due to the radial distance between the first and the second recording and thus from the plasma jet, different spray powders can be melted evenly or an optimal time can remain in the plasma. The spray powder with the lower melting temperature is usually introduced into the plasma flame via the powder injector that is further spaced axially or radially. Problems such as insufficient or excessive melting, oxidation and the like can thus be reliably avoided, which leads to correspondingly high coating qualities. The axial distance can generally be a maximum of approx. 5 cm, for example 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0 .8cm, 0.9cm, 1.0cm, 1.1cm, 1.2cm, 1.3cm, 1.4cm, 1.5cm, 1.6cm, 1.7cm, 1 .8cm, 1.9cm, 2.0cm, 2.1cm, 2.2cm, 2.3cm, 2.4cm, 2.5cm, 2.6cm, 2.7cm, 2 .8cm, 2.9cm, 3.0cm, 3.1cm, 3.2cm, 3.3cm, 3.4cm, 3.5cm, 3.6cm, 3.7cm, 3 .8cm, 3.9cm, 4.0cm, 4.1cm, 4.2cm, 4.3cm, 4.4cm, 4.5cm, 4.6cm, 4.7cm, 4 .8 cm, 4.9 cm or 5.0 cm. The exact distance depends on the spray powder to be used and the plasma torch. At axial distances greater than 5 cm, the plasma is usually no longer hot enough for most spray powders. The radial offset can generally be a maximum of approx. 2 cm, for example 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0, 8cm, 0.9cm, 1.0cm, 1.1cm, 1.2cm, 1.3cm, 1.4cm, 1.5cm, 1.6cm, 1.7cm, 1, 8 cm, 1.9 cm or 2.0 cm. Here, too, reliable melting of most spray powders is generally not possible when the maximum distance is exceeded.

In an advantageous embodiment of the invention, it is provided that the first receptacle and the second receptacle can be moved relative to one another axially and/or radially and/or independently of one another on a circumference of the plasma nozzle. As a result, the powder injector holder can be easily adapted to different plasma torches, spray powders and coating processes. Because the first receptacle and the second receptacle can be arranged independently of one another on a circumference of the plasma nozzle, identical or different spray powders can be introduced into the plasma flame at different circumferential angles. For example, a bond coat spray powder can be applied at the "9 o'clock" position (270°) while a top coat spray powder can be applied at the "3 o'clock" position (90°).

Further advantages result from the fact that the first and/or the second receptacle has an internal thread into which the first and/or second powder injector can be screwed for assembly. This allows easy assembly and disassembly of the powder injectors and simple adjustment of the radial position of each Pulverinj ector with respect to a central axis of the plasma flame. In addition, different powder injectors can be easily exchanged for one another in this way without having to remove the powder injector holder or the base body from the plasma torch, which contributes to correspondingly short changeover times.

In a further advantageous embodiment of the invention, it is provided that the main body has a first section with the first receptacle and a second section with the second receptacle along its main axis, the first section and the second section being connected to one another by a transition section. As a result, the geometry of the base body can be optimally adapted to the desired introduction of the spray powder into the plasma flame. For example, an axial and/or radial offset between the first and the second receptacle can be realized with the aid of the transition section. Furthermore, the transition section can be designed to be exchangeable or as a type of adapter for detachably connecting the first and second section in order to easily adapt the base body to different purposes.

In a further advantageous embodiment of the invention, it is provided that the powder injector holder includes a fastening means, in particular a powder tube clamp, for fixing the base body to the plasma torch in the area of its plasma nozzle. In this way, the base body can be easily mounted on the plasma torch or dismantled from the plasma torch. Since the fastening means can be exchanged, the base body can also be adapted particularly easily to different types of plasma torches.

In a further advantageous embodiment of the invention, it is provided that the fastening means and the base body comprise corresponding anti-rotation elements to prevent relative rotation of the fastening means and base body to one another and/or fastening elements for releasably fixing the base body to the fastening means. This ensures in a structurally simple manner that the fastening means and the base body are correctly aligned with one another.

A second aspect of the invention relates to a plasma torch for producing a thermal spray layer from at least two spray powders, comprising a plasma nozzle for a plasma jet, with a powder injector holder according to the first aspect of the invention being arranged in the area of the plasma nozzle. This is erfindungsge created according to a plasma torch, which has a powder injector holder, which has a simple structure and can be flexibly equipped with at least two powder injectors. Further features and their advantages can be found in the descriptions of the first aspect of the invention, advantageous configurations of the powder injector holder being to be regarded as advantageous configurations of the plasma torch and vice versa.

In an advantageous embodiment of the invention, it is provided that a first powder injector for introducing a first spray powder into the plasma jet is arranged in the first receptacle and a second powder injector for introducing a second spray powder into the plasma jet is arranged in the second receptacle, the first receptacle being arranged with respect to a The main axis of the base body is spaced axially from the second receptacle and the first receptacle and the second receptacle have a radial offset relative to one another with respect to the main axis, so that the first and the second spray powder can be introduced into the plasma jet at axially and radially different positions. With this powder tube configuration, a thermal surface coating, for example an inlet coating (outer air seal) of a high- or low-pressure compressor housing, can be produced in a much better and more stable manner. Because the first spray powder or powder component 1 (lighter, lower density) is metered in earlier in the axial direction and closer in radially, it can enter the plasma jet of the plasma torch undisturbed. Powder component 2 is dosed axially further away into the plasma jet. This mixes the two components ideally. The radially greater distance of the second powder injector from a central axis of the plasma jet means that the second or downstream powder injector does not protrude directly into the plasma or spray jet fanned out by the powder component 1 .

In a further advantageous embodiment of the invention, it is provided that the first and/or second powder injector is secured in position in the first and/or second receptacle by means of at least one lock nut. This represents a structurally simple option for securing the position of the powder injectors on or in the base body.

• 1 eine Seitenansicht einer Ausführungsform des erfindungsgemäßen Pulverinjektorhalters mit zwei axial und radial beabstandeten Pulverinjektoren;
• 2 eine perspektivische Ansicht des Pulverinjektorhalters von oben, wobei zusätzlich ein Befestigungsmittel in Form einer Pulverrohrklammer am Grundkörper angebracht ist;
• 3 eine schematische Konstruktionszeichnung des erfindungsgemäßen Pulverinjektorhalters aus unterschiedlichen Blickrichtungen; und
• 4 eine perspektivische Seitenansicht eines Plasmabrenners, an welchem der erfindungsgemäße Pulverinjektorhalter gemäß einer weiteren Ausführungsform angeordnet ist.

Further features of the invention result from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures, can be used not only in the combination specified in each case, but also in other combinations, without going beyond the scope of the invention leaving. The invention is therefore also to be considered to include and disclose embodiments that are not explicitly shown and explained in the figures, but that result from the explained embodiments and can be generated by separate combinations of features. Versions and combinations of features are also to be regarded as disclosed which therefore do not have all the features of an originally formulated independent claim. Furthermore, embodiments and combinations of features, in particular through the embodiments presented above, are to be regarded as disclosed which go beyond or deviate from the combinations of features presented in the back references of the claims. It shows:

• 1 a side view of an embodiment of the powder injector holder according to the invention with two axially and radially spaced powder injectors;
• 2 a perspective view of the powder injector holder from above, with an additional fastening means in the form of a powder tube clamp being attached to the base body;
• 3 a schematic construction drawing of the powder injector holder according to the invention from different perspectives; and
• 4 a perspective side view of a plasma torch on which the powder injector holder according to the invention is arranged according to a further embodiment.

1 shows a side view of an embodiment of the powder injector holder 10 according to the invention and is shown below in conjunction with FIG 2 explained, which shows a perspective view of the powder injector holder 10 from above, wherein in 2 in addition, a fastening means 12 in the form of a powder tube clamp is attached to a base body 14 of the powder injector holder 10 . In the present case, the base body 14 is made in one piece from a temperature-stable metal alloy and is arranged in the area of a plasma nozzle 16 of a plasma torch 18 ( 4 ). In the exemplary embodiment shown, the base body 14 has a first receptacle 20a for holding a first powder injector 22a and a second receptacle 20b for holding a second powder injector 22b. For this purpose, the first and the second receptacle 20a, 20b each comprise internal threads (not shown), into which the powder injectors 22a, 22b are screwed. The distance between the tip of the respective powder injector 22a, 22b and the plasma flame can be adjusted by the respective screw-in depth. The first and/or second powder injector 22a, 22b can be (not shown) in the first and/or that of the second receptacle 20a, 20b are secured in position. The powder injectors 22a, 22b can have the same or different diameters in order to adapt the injection speed if necessary. The base body 14 shown (double powder tube mounting block) is adapted to a standard Oerlikon Metco powder tube clamp as the fastening means 12 . In the present case, the powder injectors 22a, 22b are 3MB standard powder tubes of a 3MB plasma burner, which can be flexibly screwed in or out via a screw thread. This makes it possible, when the powder injectors 22a, 22b are worn, to simply change them and to set the radial distance from the burner axis individually as a function of the coating parameters. In addition, by selecting the available powder injectors 22a, 22b, the injection angle and the tube diameter and thus, for example, the maximum delivery rate of spray powder can be varied.

As can be seen, the first receptacle 20a is spaced axially from the second receptacle 20b with respect to a main axis H of the base body 14 . In addition, the first receptacle 20a and the second receptacle 20b have a radial offset relative to one another with respect to the main axis H. In the present exemplary embodiment, the first and second receptacles 20a, 20b are perpendicular to the main axis A of the base body 14. In principle, however, the first and/or the second receptacle 20a, 20b can also be at an angle ≠ 90° or skew to the main axis H .

3 shows a schematic design drawing of the powder injector holder 10 according to the invention from different perspectives, namely from above (top left figure), from the side (bottom left figure) and diagonally from behind (bottom right figure). It can be seen that in addition to the receptacles 20a, 20b in the front area of the powder injector holder 10, two further, fundamentally optional openings 24 are provided, which are used to arrange an anti-rotation element to prevent the fastening means 12 and the base body 14 from rotating relative to one another and/or for releasable attachment of the base body 14 on the fastening means 12 are used. The main body 14 has along its main axis H a first section 26a with the first receptacle 20a and a second section 26b with the second receptacle 20b, the first section 26a and the second section 26b being connected to one another by a transition section 28 . As a result, the geometric transition between the first and second sections 26a, 26b can be made flexible. In the present case, the transition section 28 has a ramp-like gradient on its lower side facing the plasma flame, while it has a step-like gradient on its upper side.

4 14 is a side perspective view of a plasma torch 18, which is an Oerlikon Metco 3MB torch, and to which the powder injector holder 10 of the present invention is releasably secured in accordance with another embodiment. For this purpose, the fastening means 12 connected to the base body 14 or the powder tube clamp is clamped in the region of a plasma nozzle 16 of the plasma torch 18 . An adaptation of the fastening means 12 to other burners is easily possible through slight structural changes. Additional special cleaning, cooling or blow-off devices on the powder injector holder 10 or on the plasma torch 18 are not necessary. This makes it a very simple, inexpensive and flexible design.

It can be seen that the powder injectors 22a, 22b are arranged one behind the other axially or in the direction of flow of the plasma flame. In addition, the powder injectors 22a, 22b are movable radially within their respective seats 20a, 20b. The maximum radial offset with respect to a center axis of the plasma flame is approximately 2 cm. In this way, spray powders with different melting points can be introduced into different flame temperatures of the plasma flame in order to melt them in a controlled manner. Bent powder injectors 22a, 22b or inclined bores 20a, 20b are also possible.

The powder injector holder 10 preferably has only two receptacles 20a, 20b for a total of two powder injectors 22a, 22b. In principle, however, additional powder injectors can also be distributed around the circumference if more spray powder is to be used per unit of time, ternary powder mixtures or very fine spray powder that is therefore difficult to convey.

In one embodiment, an adhesive layer powder is first conveyed through one of the powder injectors 22a or 22b in order to produce an adhesive layer on a component to be coated. Then switch to the double-pipe recording shown and create a top layer of 2 spray powders. Such a multi-stage coating process can be produced without converting the system. It can be provided that the powder injectors 22a, 22b are not arranged axially one behind the other as shown, but are arranged at different circumferential angles around the plasma nozzle or plasma flame. For example, the first powder injector 22a can be in the "9 o'clock" position for applying the adhesive layer and the top layer and the second powder injector 22b in the "3 o'clock" position for creating the top layer.

Experiments with the powder injector holder 10 according to the invention have shown that coatings such as a running-in coating can be produced much better and more reliably with this powder tube configuration. Because powder component 1 is metered in earlier in the axial direction and closer in radially (lower density, e.g. boron nitride powder), it can enter the pointed jet undisturbed. Powder component 2 (e.g. nickel powder) is dosed further away axially into the jet. This mixes the two components ideally. The radially larger spacing of the second powder injector 22b means that the pipe does not protrude directly into the spray jet fanned out by powder component 1. The two powders are mixed directly in the plasma flame via individually controlled powder feed rates and carrier gas flows, resulting in a homogeneous layered structure.

The reduction to two powder lines significantly reduces the technical complexity, eliminates possible sources of error and thus increases process stability. In addition, set-up and maintenance costs are significantly reduced. Since plasma torches 18 that are already present can often continue to be used and retrofitted using the solution mentioned, high investment costs are avoided.

In addition, the powder injector holder 10 can be used not only for plasma torches 18, but also for other inlet systems, provided these also use two powder components that are to be mixed in a temporally and spatially staggered manner.

The parameter values specified in the documents for the definition of process and measurement conditions for the characterization of specific properties of the subject matter of the invention are also to be regarded as included within the scope of the invention within the scope of deviations - for example due to measurement errors, system errors, DIN tolerances and the like.

Reference List

10

powder injector holder

12

fasteners

14

body

16

plasma jet

18

plasma torch

20a

recording

20b

recording

22a

powder injector

22b

powder injector

24

openings

26a

section

26b

section

28

transition section

H

main axis

Claims (10)

Powder injector holder (10), comprising a base body (14) for arrangement in the region of a plasma nozzle (16) of a plasma torch (18), the base body (14) having at least one first receptacle (20a) for holding a first powder injector (22a) and a second Recording (20b) for holding a second powder injector (20b). powder injector holder (10). claim 1 , characterized in that the first receptacle (20a) is spaced axially from the second receptacle (20b) with respect to a main axis (H) of the base body (14) and/or that the first receptacle (20a) and the second receptacle (20b) with respect to the main axis (H) have a radial offset to each other. powder injector holder (10). claim 1 or 2 , characterized in that the first receptacle and the second receptacle (20a, 20b) can be moved relative to one another axially and/or radially and/or independently of one another on a circumference of the plasma nozzle (16). Powder injector holder (10) according to one of Claims 1 until 3 , characterized in that the first and/or the second receptacle (20a, 20b) has an internal thread into which the first and/or second powder injector (22a, 22b) can be screwed for assembly. Powder injector holder (10) according to one of Claims 1 until 4 , characterized in that the base body (14) along its main axis (H) has a first section (26a) with the first receptacle (20a) and a second section (26b) with the second receptacle (20b), the first section ( 26a) and the second section (26b) are connected to one another by a transition section (28). Powder injector holder (10) according to one of Claims 1 until 5 , characterized in that this has a fastening means (12), in particular a powder tube clamp, for fixing the Base body (14) on the plasma torch (18) in the region of its plasma nozzle (16). powder injector holder (10). claim 6 , characterized in that the fastening means (12) and the base body (14) have mutually corresponding anti-rotation elements to prevent relative rotation of the fastening means (12) and base body (14) to one another and/or fastening elements for releasably fixing the base body (14) to the fastening means ( 12) include. Plasma torch (18) for producing a thermal spray layer from at least two spray powders, comprising a plasma nozzle (16) for a plasma jet, wherein in the area of the plasma nozzle (16) a powder injector holder (10) according to one of Claims 1 until 7 is arranged. Plasma torch (18) after claim 8 , characterized in that a first powder injector (22a) for introducing a first spray powder into the plasma jet is arranged in the first receptacle (20a) and a second powder injector (22b) for introducing a second spray powder into the plasma jet is arranged in the second receptacle (20b). , wherein the first receptacle (20a) is spaced axially from the second receptacle (20b) with respect to a main axis (H) of the base body (14) and the first receptacle (20a) and the second receptacle (20b) are one with respect to the main axis (H). have a radial offset to one another, so that the first and the second spray powder can be introduced into the plasma jet at axially and radially different positions. Plasma torch (18) after claim 8 or 9 , characterized in that the first and / or second powder injector (22a, 22b) is secured in position by means of at least one lock nut in the first and / or the second receptacle (20a, 20b).

Images