Injection nozzle having powder unit and process gas unit

Abstract

The present invention relates to an injection nozzle (1) for laser deposition welding in a forward direction (2), comprising: an optical channel (3) for guiding at least one laser beam directed toward a workpiece; a powder unit (7) disposed radially outward of the optical channel (3) for guiding at least one powder jet applied to the workpiece, wherein the powder unit (7) forms a powder portion (11) in the circumferential direction around the optical channel (3); and a process gas unit (60) disposed radially outward of the optical channel (3) for guiding a process gas, wherein the process gas unit (60) forms a process gas portion (61) in the circumferential direction, the process gas portion (61) being adjacent to the powder portion (11) at the nozzle opening (6).

Description

Technical Field

[0001] The present invention relates to an injection nozzle for laser deposition welding in the forward direction.

Background Art

[0002] Laser deposition welding is used, for example, in the fields of repair, coating, and / or joining techniques. It is possible to distinguish between conventional laser deposition welding techniques (laser metal deposition (LMD), direct metal deposition (DMD) or direct energy deposition (DED)) and high-speed laser deposition welding (HS-LMD) or extremely high-speed laser applications (EHLA). The HS-LMD method is described, for example, in the published patent applications DE102011100456A and DE102018 130798A1. Another method for laser deposition welding is known from Chinese patent application No. CN109175372A.

[0003] Functional layers can be applied to the workpiece by laser deposition welding. This generally increases the load-bearing capacity of the workpiece processed by laser deposition welding compared to the untreated workpiece. The functional layer can function, for example, as a wear protection layer. The application of the functional layer is based on the melting of the workpiece surface, the application of a powdered filler material, and subsequent cooling, so that a matrix structure with hard material particles is material-bonded to the material surface. Thus, laser deposition welding engages with the internal material structure of the workpiece and changes it. Under certain circumstances, this can result in defects in the internal material structure. These can potentially impair the desired increase in load-bearing capacity. Since the defects can be of a microscopic nature, they can only be identified with great effort. [[ID=…]]

[0004] Summary of the Invention Building upon known prior art, the object of the present invention is to provide an improved injection nozzle for laser deposition welding in the forward direction. The present invention particularly aims to increase the weld quality of the deposited functional layer and the overall workpiece, and to reduce or avoid defects in the weld joint between the powdered filler and the material surface. Defects may be poor bonding between the material surface and the applied functional layer, or between individual applied functional layers. Defects may also be pores, i.e., air pockets occurring within the applied functional layer or between the applied functional layer and the material surface. Pores may occur more frequently, especially when the material surface is a cast material. Defects may also be cracks extending perpendicularly to the material surface within the applied functional layer. Defects may also arise from the fact that powder particles of the powdered filler, particularly carbides, dissolve into the matrix material of the powdered filler, which leads to embrittlement of the matrix material. The present invention also aims to provide a reliable injection nozzle that is particularly resistant to thermal stress. The present invention may also aim to design an injection nozzle to ensure reliable and precise laser deposition welding over a very large number of cycles.

[0005] This objective is achieved by an injection nozzle having the features of claim 1. Advantageous developments arise from the dependent claims, the detailed description of the invention, and the drawings.

[0006] Therefore, a jet nozzle for laser deposition welding in the forward direction is proposed, having an optical channel for guiding at least one laser beam directed toward a workpiece. Laser deposition welding can be a method for high-speed laser metal deposition (HS-LMD). The forward direction is the direction in which the jet nozzle moves relative to the workpiece. It can result from the movement of the workpiece, particularly rotational movement, the movement of the jet nozzle, or a superposition of both. The forward direction and the corresponding forward movement can be constant throughout the process. Alternatively, they can vary at each process stage. The workpiece can be a rotationally symmetric workpiece such as a brake disc, hydraulic cylinder, pressure roller, or sliding bearing. The laser beam can shine through the optical channel. The laser beam can be supplied by a laser source, from which it is guided by an optical fiber cable to a laser system that splits the laser beam through a collimating lens and focuses the laser beam according to the process through a laser optical system before the laser beam enters the jet nozzle. The optical channel can be a hollow channel extending longitudinally through the entire jet nozzle. In addition to the laser beam, process gases can also be directed through optical channels to the workpiece surface.

[0007] The spray nozzle further comprises a powder unit positioned radially outward of an optical channel for guiding at least one powder spray applied to a workpiece, the powder unit forming a powder portion circumferentially around the optical channel. Starting from the longitudinal direction of the spray nozzle, the powder unit may be radially outward of the optical channel and may be part of an external structure enclosing the optical channel in a closed manner. The powder spray may deliver at least one powdery filler consisting of hard material particles, particularly carbides and matrix materials. The powder unit may be part of a spray nozzle provided to guide the powdery filler directly or indirectly. The powder unit may have an injector guide into which a powder injector can be inserted. It may also have an annular gap into which the powdery filler is guided. At the nozzle opening, the powder unit forms a powder portion circumferentially around the optical channel. The powder unit may be part of the nozzle opening. The nozzle opening is part of the spray nozzle facing the workpiece. The end portion of the nozzle opening has a distal region, which is the part of the nozzle opening closest to the workpiece. In the portion away from the workpiece, the injection nozzle has a proximal region and a flange portion. The proximal region and flange portion are the parts of the injection nozzle facing away from the workpiece. The nozzle may be coupled via the flange portion to further components of the laser system, such as a laser optical system or process unit. In the top view, the powder portion may extend at least to a section along the opening of the optical channel.

[0008] The injection nozzle further comprises a process gas unit positioned radially outward of the optical channel for guiding the process gas, the process gas unit forming a process gas portion in the circumferential direction. Starting from the longitudinal direction of the injection nozzle, the process gas unit may be radially outward of the optical channel and may be part of an external structure enclosing the optical channel in a closed manner. The process gas may have a favorable effect on the powder focal area and the resulting workpiece machining. The process gas unit may be part of the injection nozzle provided to guide the process gas directly or indirectly. The process gas unit may have an injector guide into which an additional injector can be inserted. It may also have an annular gap into which the process gas is guided. At the nozzle opening, the process gas unit forms a process gas portion circumferentially around the optical channel. The process gas unit may be part of the nozzle opening. In the top view, the process gas portion may extend at least to a section along the opening of the optical channel. The process gas portion may be part of the process gas unit from which the process gas is injected from the injection nozzle.

[0009] The process gas portion is connected to the powder portion at the nozzle opening in the circumferential direction. This means that the process gas portion is directly adjacent to the powder portion in the circumferential direction. This allows the process gas to have a stable influence on the powder focal area and continuous laser deposition welding. The process gas portion may be connected to the powder portion in such a way that a transition occurs in the circumferential direction, so that the interior is separated from the process gas portion and the powder portion from the outside. The separation may be such that as little fluid as possible is exchanged between the inside and outside. This can help stabilize the process zone and, at the same time, prevent powder particles from sticking to one end face of the injection nozzle, and thus help increase the service life of the injection nozzle.

[0010] The injection nozzle can therefore offer increased versatility in (i) laser beam guidance, (ii) use of powdered filler material, (iii) thermal management, and (iv) protection of the laser system including the injection nozzle. This makes it possible to provide multiple independent process zones with high precision. The process zones can be divided into zones for laser deposition welding and zones for pre-treatment and / or post-treatment. In the zone for laser deposition welding, interaction occurs between at least one laser beam and the powdered filler material. Pre-treatment and / or post-treatment may be cleaning of the material surface, preheating of the material surface before application of the powdered filler material, post-heating of the material surface after application of the powdered filler material, or a combination thereof. During pre-treatment and / or post-treatment, the laser beam may be irradiated onto the workpiece without interaction with the powdered filler material. Independent process zones can increase the applied functional layer, in particular the wear protection layer and the overall weld quality of the workpiece, and therefore the load-bearing capacity. Additional process gases can stabilize the process zones and increase the accuracy of the laser deposition welding and the service life of the injection nozzle.

[0011] In particular, the injection nozzle can reduce the occurrence of bonding failures. This is because bonding failures can occur when the surface is heated by the laser beam, such as when the workpiece or a previously welded functional layer is not sufficiently heated. This insufficient heating may result from keeping the laser power of a single laser beam low to avoid overheating of the powdered filler material. Due to increased variability in laser beam induction, increased variability in the application of the powdered filler material, and / or increased variability in the thermal management of the injection nozzle, bonding failures can be reduced or even prevented, in particular, by stabilizing the powder portion, the laser beam guide, and / or the process gas portion positioned circumferentially adjacent to the powder focal area.

[0012] In particular, the injection nozzle can also reduce the occurrence of pores between the welded functional layer and the surface heated by the laser beam. This is because pores can occur when lamellae in the workpiece, especially graphite lamellae, vaporize due to laser radiation. Pores can also occur if the surface being machined has impurities, such as oil, grease, coolant lubricant, or oxides, which cannot be completely removed by the welding process. The vaporization of unwanted impurities may be a result of avoiding bonding failures due to insufficient heating, as the laser power of a single laser beam is set very high. Due to increased variability in laser beam induction, increased variability in the application of powdered filler material, and / or increased variability in the thermal management of the injection nozzle, the occurrence of pores can be reduced or even prevented, in particular, by stabilizing the powder portion, the laser beam guide, and / or the process gas portion positioned circumferentially adjacent to the powder focal area.

[0013] In particular, the injection nozzle can also reduce the occurrence of cracks in the welded functional layer. This is because cracks can occur when the temperature gradient between the strongly heated powdered filler and the weakly heated workpiece surface is very large, and the shrinkage of the material during cooling creates stress that causes cracks. Cracks may also result from setting the laser power of a single laser beam very high to avoid bonding failures due to insufficient heating. Due to increased variability in laser beam induction, increased variability in the application of powdered filler, and / or increased variability in the thermal management of the injection nozzle, crack occurrence can be reduced or even prevented, in particular, by stabilizing the powder portion, the laser beam guide, and / or the process gas portion positioned circumferentially adjacent to the powder focal area.

[0014] In particular, the injection nozzle can also reduce the dissolution of hard material particles, especially carbides, in the matrix material. The powdered filler material may contain hard material particles, especially carbides, and the matrix material. The hard material particles should exist in an undissolved state within the welded functional layer to increase the load-bearing capacity of the functional layer. However, if the powdered filler material is exposed to excessively high radiation intensity, the hard material particles will dissolve, causing melting of the hard material particles. The melted hard material particles make the welded functional layer brittle due to the low ductility of the matrix material, meaning that, for example, stress caused by shrinkage cannot be absorbed by the matrix material when the workpiece is cooled or subjected to load. Due to increased variability in laser beam induction, increased variability in the application of the powdered filler material, and / or increased variability in the thermal management of the injection nozzle, the dissolution of hard material particles can be reduced or even prevented, in particular, by stabilizing the powder portion, the laser beam guide, and / or the process gas portion positioned circumferentially adjacent to the powder focal area.

[0015] In particular, the injection nozzle can prevent powder particles from adhering to the nozzle opening. In principle, high process heat, reflected laser radiation, and / or metal vapor plumes can cause the filler material to adhere to the nozzle opening, or even weld, which can disrupt the gas and powder flow and consequently impair the process results. The metal vapor plume is a result of the partial vaporization of the material due to laser deposition welding. It causes scattering and / or absorption of laser radiation, which can consequently impair the preheating of the workpiece. This can further promote the formation of poor bonding. Due to increased variability in the induction of the laser beam, increased variability in the application of powdered filler material, and / or increased variability in the thermal management of the injection nozzle, undesirable dissolution of hard material particles and propagation of metal vapor plumes can be reduced or even prevented, in particular, by stabilizing the process gas portion, which is positioned circumferentially adjacent to the powder portion, laser beam guide, and / or powder focal area.

[0016] At least one laser beam, particularly at least one circular laser beam and / or one elliptical laser beam, can be guided within the nozzle opening to form two or more process zones in interaction with the powdery filler material, thereby facilitating welding behavior and reducing the occurrence of defects in welded joints, particularly poor bonding, porosity, cracks, and / or carbide dissolution in the matrix material, and increasing the load-bearing capacity of the applied functional layer. By providing a process gas unit, the process zones can be influenced in a targeted manner. On the one hand, this prevents powder particles from sticking to or even welding to the nozzle opening. Secondly, the propagation of vapor plumes can be prevented by keeping the vapor plumes within the area between the nozzle opening and the workpiece, particularly within the powder portion and the process gas portion. Thus, the process gas portion contributes to reducing the aforementioned defects.

[0017] In one embodiment, a process gas unit can supply process gas to a workpiece by forming an exhaust opening on one end face of an injection nozzle, and an additional injector for supplying process gas without filler material is located within at least one exhaust opening. The exhaust opening may be designed on the end face such that the surface on which hard material particles may adhere is minimized. The process gas supplied from the exhaust opening may be assisted by process gas supplied inside an optical channel. An additional injector may be located within each exhaust opening. The additional injector is different from an injector located within the injector guide of the powder unit. The latter carries hard material particles to the workpiece surface, while the former carries process gas.

[0018] In one embodiment, the process gas portion extends around the optical channel, particularly in an arc shape, in sections along at least the arc of the slotted hole. Similar to a circular arc, the arc of the slotted hole represents a line surrounding the slotted hole within the sector. The remainder of the slotted hole not covered by the arc of the slotted hole to which the process gas portion extends can be filled with the powder portion. The process gas portion may extend at least partially along a partial circular section, particularly a partial circular section located forward in the forward direction, to form an arc shape. This also helps to stabilize the laser beam guidance and / or the powder focal area.

[0019] In one embodiment, the process gas portion extends circumferentially around the optical channel over a winding angle of 5° to 180°, particularly 45° to 120°, relative to the center point of the optical channel. This means that the process gas portion may extend around the optical channel in smaller sections than the powder portion. This ensures sufficient supply of powder through the powder unit and, in particular, the injector located therein, while avoiding the adhesion or diffusion of vapor plumes. Precise adaptation of the powder portion and the process gas portion to each process condition enables defect-free and efficient welding behavior.

[0020] In one embodiment, the process gas portion and the powder portion together completely surround the optical channel circumferentially, i.e., 360°. Thus, the jets ejected from the process gas portion and the powder portion can be separated into an interior formed inside the jet and an exterior formed outside the jet. The metallic vapor plume, also known as a vapor plume, resulting from the interaction of powder particles with the laser beam, cannot thus leak out from the interior, which prevents undesirable interaction of the vapor plume with the workpiece.

[0021] In one embodiment, the process gas unit has a supply opening through which process gas can be supplied to the process gas unit, and at least one discharge opening through which the process gas exits the process gas unit. The supply opening may be coupled to a supply hose that directs the process gas from a gas container to an injection nozzle. The process gas unit may have just one supply opening. At least one discharge opening is fluidly connected to the supply opening and shaped to ensure process-compliant discharge of the process gas toward the workpiece surface. At least one distribution arm is provided between the supply opening and at least one discharge opening to guide the process gas. Additional injectors may be provided within the distribution arm and / or discharge opening. Alternatively, the process gas may exit directly from the distribution arm and / or discharge opening.

[0022] In one embodiment, the process gas unit has a plurality of, in particular, three, exhaust openings, each connected to a single supply opening. The plurality of exhaust openings ensure the distribution of process gas along the circumferential direction. As an alternative to the plurality of exhaust openings, arc-shaped slot-like exhaust openings may also be provided, which also ensure the distribution of process gas along the circumferential direction. The plurality of exhaust openings contribute to stabilizing the vapor plume and preventing powder particles from adhering to the nozzle opening.

[0023] In one embodiment, the process gas portion is formed in the region of the nozzle opening facing the forward direction. In the top view, the region of the nozzle opening facing the forward direction is provided at the end of the nozzle closest to the forward direction. One end face of the process gas portion points towards the workpiece. The process gas portion may extend circumferentially around the optical channel over a certain angular range. The angular range over which the process gas portion extends may be smaller than the angular range over which the powder portion extends. The region where the process gas portion is formed may correspond to the position and orientation of the powder injector that applies the powdered filler material to the workpiece.

[0024] In one embodiment, the powder section has a plurality of injector guides into which a powder injector can be inserted. The injector guides may be cylindrical or conical through-openings within the nozzle opening area into which a powder injector can be inserted. The injector guides may be introduced into the nozzle opening by machining. However, preferably, they are provided at the additive manufacturing stage of the injection nozzle. The injector guides may be adapted to the powder injector used. The injector guides of the powder section are different from the distribution arms of the process gas section. The powder injector is also different from an additional injector that delivers the process gas.

[0025] In one embodiment, the inner diameter of at least one discharge opening is smaller than the inner diameter of the injector guide. The volumetric flow rate of the process gas may be affected by the inner diameter of at least one discharge opening. The gas flow rate of the process gas through at least one discharge opening may be in the range of 1 l / min to 100 l / min, particularly 5 l / min to 50 l / min. The gas flow rates of the carrier gas flowing out from the powder injector in the injector guide and the process gas flowing out from at least one discharge opening may be substantially equal. The process gas may also exit through an optical channel in addition to the discharge opening. The gas flow rates of the carrier gas and the process gas may also be compared with each other. For example, the proportion of the carrier gas may be greater than or less than the proportion of the process gas. The respective ratios of the process gas to the carrier gas can be adjusted according to the process.

[0026] In one embodiment, a first powder injector is prepared to deliver a first powder mass flow rate, and a second powder injector is prepared to deliver a second powder mass flow rate, wherein the first powder mass flow rate is different from the second powder mass flow rate. The first powder injector may be supplied to a first powder portion, and the second powder injector may be supplied to a second powder portion. The first powder injector may be positioned to interact with the primary beam of a laser beam. The second powder injector may be positioned to interact with the secondary beam of a laser beam. The primary and secondary beams may carry the same or different energies. Providing the first and second powder mass flow rates allows the injection nozzle to achieve two or more process zones, which further contributes to the increased variability of the injection nozzle. The gas flow rate exiting at least one exhaust port may be adjusted according to the first powder mass flow rate among the second powder mass flow rates.

[0027] In one embodiment, the powder portion forms an annular gap segment, particularly instead of an injector guide. The annular gap segment can form a uniform powder focal point that coincides, for example, with the center point of at least one laser beam. In the case of an annular gap segment, the powdery filler material is applied to the workpiece along a horseshoe-shaped jet.

[0028] In one embodiment, the optical channel is adapted to guide multiple laser beams, the multiple having a first laser beam as a primary beam and a second laser beam as a secondary beam. The primary and secondary beams may originate from the same optical fiber cable. The supplied laser light can be split into parallel beams via a collimating lens. The beam bundle can be formed from a single laser beam into primary and secondary beams, for example, using a wedge plate. In this case, the primary and secondary beams may have the same wavelength and carry the same energy. Alternatively, the primary and secondary beams may differ in terms of their wavelength and energy. The center points of the primary and secondary beams may be offset in the forward direction according to the center point of the optical channel.

[0029] In one embodiment, the injection nozzle is manufactured by an additive manufacturing process, particularly powder bed fusion. For this purpose, the injection nozzle can be made of copper or a copper alloy, particularly a copper-chromium-zirconium alloy. This is suitable for the additive manufacturing process on the one hand and ensures sufficient strength, thermal conductivity and heat resistance to withstand the process requirements on the other hand. In powder bed fusion, the material to be processed is in powder form. The laser beam heats the powder along the provided geometry, thereby liquefying the powder and forming material bonds. Powder bed fusion can be formed using, for example, selective laser melting (SLM) or selective laser sintering (SLS).

[0030] In one embodiment, the nozzle mouth has a chamfer, whereby a part of the nozzle mouth is cut off, and the chamfer extends in a plane that is substantially planar and inclined with respect to the longitudinal direction of the injection nozzle. The chamfer can cut off a powder portion and a forward section without powder or a process gas portion in the circumferential direction around the light channel. The chamfer reduces the volume of the nozzle mouth compared to embodiments without chamfer. This means that the nozzle mouth takes up a smaller installation space. The injection nozzle having a chamfer can be used, for example, to coat a brake disc having a mounting portion protruding axially from a functional surface to be coated. The chamfer ensures that the injection nozzle can move flexibly on the functional surface to be coated and can move close to the holder. The chamfer can extend into the distal region in the form of a passage over a slotted hole. The passage defines the orientation of the chamfer on the nozzle mouth. At the end face of the injection nozzle facing the workpiece, the passage extends along a straight line or an arc that does not intersect or contact the slotted hole. The distance of the passage from the center point of the light channel is greater than the distance of the corresponding section of the slotted hole from the center point of the light channel. The distance between the passage and the outer edge of the slotted hole is selected such that the wall thickness therebetween ensures sufficient robustness and load-bearing capacity of the injection nozzle.

[0031] In one embodiment, the injection nozzle is adapted to guide at least one laser beam along the longitudinal direction of the injection nozzle such that the at least one laser beam is orthogonal to the cross-sectional area. Further, the optical channel may be adapted to guide shielding gas along a radially outer portion to shield the process zone.

[0032] The features according to the disclosure contribute in part to overcoming the deficiencies of laser deposition welding mentioned at the beginning, both by themselves and in combination.

Brief Description of the Drawings

[0033] Preferred further embodiments of the present invention are described in more detail by the following description of the drawings. [Figure 1] A schematic view of an injection nozzle during laser deposition welding is shown. [Figure 2] A side view of the injection nozzle is shown. [Figure 3] A perspective view of the injection nozzle from FIG. 2 is shown. [Figure 4] The injection nozzle from FIG. 2 connected to other components is shown. [Figure 5] A top view of the distal region of the injection nozzle from FIG. 2 is shown. [Figure 6] A top view of the flange portion of the injection nozzle from FIG. 2 is shown. [Figure 7] Another perspective view of the injection nozzle from FIG. 2 is shown. [Figure 8] A perspective cross-sectional view of the injection nozzle from FIG. 2 is shown. [Figure 9] A top view of the distal region of the injection nozzle including a process gas unit is shown. [Figure 10] A top view of the distal region of the injection nozzle having a process gas unit with a powder focus corresponding to the focus of the primary laser beam is shown. [Figure 11] A perspective view of the injection nozzle having a process gas unit is shown. [Figure 12] A side view of the injection nozzle having a process gas unit is shown. [Figure 13] Further representation of an injection nozzle with a process gas unit is shown. [Figure 14] A side view of a further embodiment of an injection nozzle having a geometrically conforming nozzle opening is shown. [Figure 15] A top view of a further embodiment of an injection nozzle having a geometrically conforming nozzle opening is shown. [Modes for carrying out the invention]

[0034] Preferred exemplary embodiments are described below with reference to the drawings. In these cases, elements that are the same, similar, or have the same effect are given the same reference numerals in different drawings, and repeated descriptions of these elements are omitted in some cases to avoid redundancy.

[0035] Figure 1 shows an injection nozzle 1 for laser deposition welding in forward direction 2. Forward direction 2 is the direction in which the injection nozzle 1 moves relative to the workpiece 100. It can result from the movement of the workpiece 100, particularly rotational movement, the movement of the injection nozzle 1, or a superposition of the movement of the workpiece 100 and the injection nozzle 1. Forward direction 2 and the corresponding forward movement may be constant throughout the process. Alternatively, they may vary at each process stage. The workpiece 100 may be a rotationally symmetric workpiece such as a brake disc, hydraulic cylinder, pressure roller, or sliding bearing. At least one laser beam 110 is emitted from an optical channel 3 having a transverse surface 4. The optical channel 3 may also be adapted to guide a shielding gas 150 along its radially outer portion to shield the process zone and prevent oxidation. The optical channel 3 is surrounded by an external structure 5, which has a nozzle opening 6 and subsequently houses a powder unit 7. The powder unit 7 may have, for example, a plurality of injector guides 19 (see Figure 3), and a powder injector 16 (see Figure 4) may be inserted into each of the injector guides 19. As an alternative to individual injector guides 19, the powder unit 7 may have an annular powder gap channel. The powdered filler material 120 is directed to the workpiece 100 via the powder unit 7 and the powder injector 16 located inside it. The laser beam 110 heats the workpiece 100 so that a weld pool 130 is formed on the material surface. In addition, the laser beam 110 heats the powdered filler material 120, which has hard material particles and matrix material. For this purpose, the laser beam 110 may have reduced core strength. As soon as the weld pool 130 cools, a welded functional layer 140, which is, for example, a wear protection layer, is formed from the hard material particles and matrix material. The welded functional layer 140 makes the material surface more resistant and increases its load-bearing capacity.

[0036] Figure 2 shows the injection nozzle 1 in a side view with the forward direction 2 oriented out of the drawing plane. The injection nozzle 1 can be coupled via a flange portion 9 to other components of the laser system, such as a laser optical system or a process adapter. The proximal region 10 is attached to the flange portion 9. Coolant inlet 13 and coolant outlet 14, which are part of the cooling system of the injection nozzle 1 and project radially from the injection nozzle 1, may be provided at least partially within the proximal region 10. The distal region 8 is formed at the end of the injection nozzle 1 opposite to the proximal region 10. The distal region is part of the funnel-shaped nozzle opening 6. It has a powder section 11 within the section, in which powder units 7 are arranged circumferentially around the optical channel 3. The powder section 11 is followed circumferentially by a forward section 12 without powder units. The forward section 12 may be designed as a process gas section 61, which is part of a process gas unit 60 (see, for example, Figure 9).

[0037] Figure 3 shows a perspective view of the injection nozzle from Figure 2. The optical channel 3 is a hollow channel having a transverse surface 4 into which at least one laser beam 110 extends. The external structure 5 surrounds the optical channel 3 from the flange portion 9 to the distal region 10. The nozzle opening 6 is substantially the funnel-shaped region of the injection nozzle 1. The funnel shape of the nozzle opening 6 functions, among other things, to allow the nozzle opening 6 to form a plurality of injector guides 19 in the region of the powder unit 7. Powder injectors 16 (see Figure 4) are inserted into each of these injector guides 19 and direct the powdered filler material 120 onto at least one laser beam 110 and / or the workpiece 100 according to the process. The powder unit 7 extends along the powder portion 11 which is connected in the circumferential direction to the forward portion 12 which is not the powder unit. The forward portion 12 is the area of ​​the nozzle opening 6, where no injector guide 19 is provided, and therefore no powdered filler material 120 is supplied through it. In one embodiment, the forward portion 12 may be formed as a process gas portion 61, through which the process gas is supplied. The injection nozzle 1 is manufactured by an additive manufacturing process, in particular by powder bed fusion. For this purpose, the injection nozzle 1 may be made from a copper-chromium-zirconium alloy. This is suitable for additive manufacturing processes on the one hand, and ensures sufficient strength, thermal conductivity and heat resistance to withstand the process requirements on the other hand. In powder bed fusion, the material to be processed is in powder form. A laser beam heats the powder along a provided geometry, thereby liquefying the powder and forming material bonds. Powder bed fusion may be formed using, for example, selective laser melting (SLM) or selective laser sintering (SLS).

[0038] Figure 4 shows the injection nozzle 1 to which additional components are attached. A connecting ring 15 is connected to a flange portion 9, which attaches the injection nozzle 1 to a connecting unit, such as a laser optical system or process adapter. A powder injector 16 is inserted into an injector guide 19 of the powder unit 7. Powdered filler material 120 is transported by the powder injector 16 and applied to the workpiece 100 at a provided focus. Individual powder injectors 16 may use different powder focuses relative to each other. Alternatively, powder injectors 16 may be oriented to the same focus. The powder injector 16 is located in the powder portion 11 within the provided injector guide 19 of the powder unit 7. There is no powder injector 16 in the forward portion 12. An intake connector 17 is also inserted into the coolant intake 13, and an outlet connector 18 is inserted into the coolant outlet 14. These connect the coolant intake 13 and the coolant outlet 14 to the coolant circuit.

[0039] Figure 5 shows the injection nozzle 1 in a top view of the distal region 8. The cross-sectional area of ​​the optical channel 3, perpendicular to the longitudinal direction of the injection nozzle 1, is deviated from a circular shape and extends in the forward direction 2. In the distal region 8, the cross-sectional area of ​​the optical channel 3 is designed in the shape of a slotted hole, where the two opposite ends of a rectangular portion are joined by a partially circular portion. Two laser beams, a primary beam 111 and a secondary beam 112, are guided within the optical channel 3. The primary beam 111 and the secondary beam 112 may originate from the same optical fiber cable. The supplied laser light can be split into parallel beams via a collimating lens. The beam bundles can be formed from a single laser beam, for example, using a wedge plate. The respective center points of the primary beam 111 and the secondary beam 112 are offset from the center point 20 of the optical channel 3 along a common line in the forward direction 2.

[0040] In this example, the secondary beam 112 is positioned ahead of the primary beam 111 in the forward direction 2 and does not interact with the powder focus area. The secondary beam 112 can therefore be used to preheat the workpiece 100 before the primary beam 111 and the powdery filler material 120 heated by the primary beam 111 affect the workpiece 100. The secondary beam 112 therefore creates a first process zone that functions to preheat the workpiece 100, and the primary beam 111 creates a second process zone that functions to weld the powdery filler material 120 onto the workpiece 100. These different process zones enable defect-free welding, in particular, without defects such as poor bonding, porosity, cracks, and / or carbide dissolution in the matrix material. It is also possible to guide the secondary beam 112 behind the primary beam 111 in the forward direction 2. Therefore, the secondary beam 112 can be used to reheat the workpiece 100, thereby contributing to more uniform cooling that prevents the occurrence of traps or other defects.

[0041] The primary beam 111 and the secondary beam 112 are positioned in close proximity to each other. The front partial arc portion of the slotted hole in the forward direction 2 is concentric with the secondary beam 112, while the rear partial arc portion of the slotted hole is concentric with the primary beam 111. The center of gravity of the cross-sectional area is eccentric with respect to the center points of the primary beam 111 and the secondary beam 112. A tertiary beam may be provided, so that, for example, the secondary beam is positioned in front of the primary beam in the forward direction, and the tertiary beam is positioned behind the primary beam in the forward direction. The individual laser beams are guided toward each other without shielding, so that there is exactly one optical channel 3 with exactly one lateral surface 4, which results in minimal heat loss.

[0042] In Figure 5, the primary beam 111 is positioned behind the secondary beam 112 in the forward direction 2 without radial offset, and since the secondary beam 112 functions to preheat the workpiece, it is desirable that the powdery filler material does not interact with the secondary beam 112. This ensures that, on the one hand, the secondary beam 112 can perform only the function of preheating the workpiece, and on the other hand, that the powdery filler material is heated only by the primary beam 111 and not by the secondary beam 112. This is achieved by the injection nozzle 1 forming a powder unit 7 in the region of the nozzle opening 6 such that it forms a powder portion 11 circumferentially around the optical channel 3, and a forward portion 12 without a powder unit is connected circumferentially to the powder portion 11. In addition to the powder unit 7, a process gas unit 60 may also be formed, thereby forming a process gas portion 61, in which case the forward portion 12 is formed as the process gas portion 61. The forward portion 12 is formed in the region of the nozzle opening 6 facing the forward direction 2. The powder portion 11 extends along the slotted holes that form the cross-sectional area of ​​the optical channel 3 in the distal region 8. Similar to an arc, the powder portion 11 extends around the optical channel 3, particularly along the arc of the horseshoe-shaped slotted holes. Thus, the powder portion 11 extends circumferentially around the optical channel 3 over winding angles of less than 360° with respect to the center point of the optical channel, particularly 90° to 330°, and even more particularly 180° to 300°. This ensures that the powdery filler material flowing out from the injector 16 inserted into the injector guide 19 interacts only with the primary beam 111. Therefore, the secondary beam 112 can form a process zone independent of the primary beam 111. The powder portion 11 and the forward portion 12 form a slotted hole shape when viewed from above. This also helps to reduce or avoid the defects identified at the beginning.

[0043] Figure 6 shows the injection nozzle 1 in a top view of the flange portion 9. The cross-sectional area of ​​the optical channel 3 perpendicular to the longitudinal direction of the injection nozzle 1 is also deviate from a circular shape in the region of the flange portion 9 and extends in the forward direction 2. The extension of the cross-sectional area may decrease from the distal region 8 to the flange portion 9. In the region of the nozzle opening 6, the cross-sectional area can be extended to be at least 1.5 times larger in the forward direction and at least 2 times larger intersecting the forward direction. The flange portion 9 has such a radial extension that the injector guide 19 is not visible from the top view of the proximal region 10.

[0044] Figure 7 shows the injection nozzle 1 in a further perspective view. The nozzle opening 6 has a curved funnel shape. Injector guides 19 into which a powder injector 16 can be inserted are formed within the individual curves. In the forward direction 2, the optical channel extends in a manner that deviates from a circular shape to achieve the advantages of this disclosure. Circumferentially around the optical channel 3, the nozzle opening 6 has a powder unit 7. This extends circumferentially around the optical channel 3 along a powder unit 11 adjacent to a forward portion 12 without powder.

[0045] Figure 8 shows a perspective cross-sectional view of the injection nozzle 1. The optical channel 3 has a conical shape, and therefore the cross-sectional area of ​​the optical channel 3 extending perpendicular to the longitudinal direction of the injection nozzle 1 is smaller in the distal region 8 than in the proximal region 10. The coolant inlet 13 and coolant outlet 14 are located within the proximal region 10 of the injection nozzle 1 and project radially from the injection nozzle 1. Figure 8 shows a cross-sectional view of the injector guide 19, which is located within the powder section 11. The injector guide 19 for powder injection guidance is not provided within the forward section 12. The injection nozzle 1 has a cooling system 30. A cooling medium, such as water, is supplied back to the radially inward cooling chamber 31 via the coolant inlet 13 in the proximal region 10. The cooling medium can be distributed circumferentially around the optical channel 3 in the proximal region 10. The cooling medium extends from the proximal region 10 to the nozzle opening 6. The radially inward cooling chamber 31 is formed at least within the nozzle opening 6. It may be designed in the shape of an annular gap segment extending from the distal region 8 to the proximal region 10 and extending around the optical channel 3. In the region of the nozzle opening 6, the radially inward cooling chamber 31 extends circumferentially around the optical channel 3. The radially inward cooling chamber 31 has a constant width radially in the region of the nozzle opening 6 and is concentric with the optical channel 3 in a cross-sectional area extending perpendicular to the longitudinal direction of the injection nozzle 1.

[0046] The transition section 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is provided in the distal region 8. The radially outer cooling chamber 33 has a radial width that decreases radially toward the distal region 8 in the region of the nozzle opening 6. The radially outer cooling chamber 33 extends from the distal region 8 to the proximal region 10, where it supplies the heated coolant to the coolant outlet 14. The transition section 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is located within the forward section 12. The forward section 12 does not have an injector guide 19 for guiding the powder injection beam, which means that there is sufficient installation space for the transition section 32.

[0047] The radially outer cooling chamber 33 has a cooling structure to increase its surface area. The cooling structure can be manufactured by an additive manufacturing process. It ensures that heat dissipation is promoted by ensuring contact with as much surface area as possible as the cooling medium returns from the distal region 8 to the proximal region 10. The cooling structure is optimized to keep the pressure loss of the cooling medium as low as possible. This can be achieved by a honeycomb structure 34, as shown in Figure 8.

[0048] Figure 9 shows the injection nozzle 1 in a top view of the distal region 8. The primary beam 111 and secondary beam 112 are guided within the optical channel 3. The secondary beam 112 is ahead of the primary beam 111 in the forward direction 2 and does not interact with the powder focal area, as will be described in more detail in relation to Figure 5. When the laser beam interacts with the material surface and the powder injection, a vapor plume may form between the injection nozzle 1 and the workpiece 100. If this is not suppressed, it may interact with at least one laser beam and / or the raw and / or processed material surface in an undesirable manner. In the region adjacent to the powder portion 11, the forward portion 12 can therefore be designed as a process gas portion 61. This is formed by positioning a process gas unit 60 radially outside the optical channel 3, which directs the process gas toward the workpiece. The process gas portion 61 can prevent undesirable diffusion of the vapor plume and therefore contribute to precise workpiece machining with a robust injection nozzle design. The process gas portion 61 can form at least one, in this example, three, exhaust openings 62. The exhaust openings 62 are formed on one end face of the injection nozzle 1. Additional injectors for supplying process gas can be inserted into each exhaust opening 62 without filler material. The inner diameter of the exhaust openings 62 may be smaller than the inner diameter of the injector guide 19. The process gas portion 61 also prevents powder particles from adhering to the end face of the injection nozzle 1. In this respect, the process gas portion 61 also increases the service life of the injection nozzle 1. The process gas portion 61 and the powder portion 11 can be supplied circumferentially around slotted holes formed by the optical channel 3. Thus, the primary beam 111 and the secondary beam 112 are entirely within the beam consisting of powder injection and process gas injection.

[0049] The gas flow rate of the process gas passing through the discharge port 62 can be in the range of 1 l / min to 100 l / min, particularly 5 l / min to 50 l / min. The gas flow rates of the conveyor gas flowing out from the powder injector 16 or injector guide 19 and the process gas flowing out from the discharge port 62 may be substantially equal. It is also possible for the process gas to exit from the optical channel 3 in addition to the discharge port 62. The gas flow rates of the conveyor gas and the process gas can also be compared with each other. For example, the proportion of the conveyor gas may be greater than or less than the proportion of the process gas. The respective ratios of the process gas to the conveyor gas can be adjusted according to the process.

[0050] Figure 10 illustrates the winding angle 26 of the powder portion 11 extending around the center point 20 of the optical channel 3, as shown from Figure 9. In this case, the winding angle 26 extends to 240°. The remaining 120° of the complete encirclement of the optical channel 3 is formed in this case by the process gas portion 61. Thus, the powder injection and process gas injection completely encircle the optical channel 3. The powder injector 16 or injector guide 19 is designed so that the powder injection ejected therefrom is focused on a first powder focus 21. The primary beam 111 has a beam center point that coincides with the first powder focus 21, forming a powder focus area. The primary beam 111 and the secondary beam 112 are offset from each other in the forward direction 2. The secondary beam 112 does not interact with the powder focus area. The process gas portion 61 prevents leakage of vapor plume and adhesion of powder particles to the front of the injection nozzle 1.

[0051] Figure 11 shows a perspective view of the injection nozzle 1. A supply opening 63 is provided within the process gas section 60. The supply opening 63 is located in the region of the nozzle opening 6 facing away from the workpiece. Process gas is supplied to the process gas section 60 through the supply opening 63. Starting from one supply opening 63, the process gas can be directed to individual discharge openings 62 through distribution arms 64 formed within the process gas section 60. The number of distribution arms 64 corresponds to the number of discharge openings 62. The distribution arms 64 extend within the process gas unit 60 along the nozzle opening 6, distributing the process gas from the supply opening 63 to the discharge openings 62. The distribution arms 64 may form sections into which additional injectors may be inserted. These may allow the process gas to exit at a certain angle to the workpiece surface. The distribution arms 64 are designed in a manner appropriate to the process so that the process gas can be efficiently directed to the workpiece surface.

[0052] Figure 12 shows a side view of the injection nozzle 1, the workpiece 100, and the area between them. The powder unit 7 extends so that the powder injection can be directed from the powder portion 11 of the nozzle opening 6 onto the workpiece 100 in a process-appropriate manner. The powder unit 7 is followed by a process gas unit 60 that guides the process gas from the supply opening 63 to the discharge opening 62 via a distribution arm 64 so that the process gas can be directed from the process gas portion 61 of the nozzle opening 6 onto the workpiece in a process-appropriate manner. The interaction between the primary beam 111, the powder injection, and the workpiece surface produces a first vapor plume 65. The interaction between the secondary beam 112 and the material surface produces a second vapor plume 66. The process gas flows from the discharge opening 62 so that the first vapor plume 65 and the second vapor plume 66 do not extend radially from the extended region of the optical channel 3.

[0053] Figure 13 shows the injection nozzle 1 in three different views. Figure 13a) is a perspective view. In the area of ​​the nozzle opening 6 facing the flange portion 9, a supply opening 63 is provided into the process gas unit 60. This represents a central interface through which the process gas becomes available to the nozzle opening 6. Starting from the supply opening 63, the process gas is distributed along a distribution arm 64 that distributes the process gas from the supply opening 63 circumferentially around the optical channel 3. The discharge opening 62, through which the process gas exits toward the workpiece, is located at the distal end of the distribution arm 64. The discharge opening 62 is part of the process gas portion 61 and extends in an arc shape circumferentially around the optical channel 3. The powder portion 11 is horseshoe-shaped and adjacent to the discharge opening 62. Thus, in this example, the optical channel 3 is completely, i.e., 360°, surrounded by the powder portion 11 and the process gas portion 61.

[0054] Figure 13b) is a cross-sectional view. A powder unit 7 is provided in the rear region in the forward direction 2, and the powder unit 7 forms a powder portion 11 through which an injector guide 19 extends. Each injector guide 19 is adapted to accommodate a powder injector 16. A process gas unit 60 may be provided in the forward region in the forward direction 2, and the process gas unit 60 forms a process gas portion 61 through which a distribution arm 64 extends. The distribution arm 64 may accommodate additional injectors. Alternatively, the process gas is directed directly from the distribution arm 64 to the material surface. The distribution arm 64 has a curved shape along its longitudinal direction. The injection nozzle 1 has a cooling system 30 having a radially inward cooling chamber 31 and a radially outward chamber 33. Due to the embodiment of the forward portion 12 as the process gas portion, the radially outward cooling chamber 33 surrounds the distribution arm 24 in the forward region of the nozzle opening 6 in the forward direction 2. The process gas can therefore contribute to the thermal management of the injection nozzle 1.

[0055] The injection nozzle 1 has an absorbing portion 40 on the lateral surface 4 of the optical channel 3 for receiving reflected radiation from the workpiece 100. The absorbing portion 40 may have a geometric shape that facilitates the absorption of reflected radiation. The absorbing portion may extend variably circumferentially around the optical channel 3, and in particular may be configured to extend around the entire circumference of the optical channel 3. The absorbing portion may also extend variably in the longitudinal direction of the optical channel 3. In particular, the absorbing portion 40 is not formed on the distal lateral surface of the nozzle opening 6, but a smooth inner end portion is formed to allow for good cleaning of the inside of the nozzle opening 6. The shape of the absorbing portion 40 can be adapted to the expected back-reflected radiation. The absorbing portion 40 may be formed from the same material as the rest of the injection nozzle. The absorbing portion 40 may have a coating. The laser radiation absorbed by the absorbing portion 40 can be at least partially dissipated by the cooling system 30. The back-reflected radiation is absorbed by the absorbing portion 40 so that a portion of the radiation penetrating into other components of the laser system, such as the laser optical system, is reduced or eliminated. This increases process reliability and laser beam accuracy. The service life of the injection nozzle 1 and the laser system is also increased. The improved characteristics of the injection nozzle 1, due to its absorption surface, enable the aforementioned defect-free welding behavior.

[0056] Figure 14 shows a further embodiment of the injection nozzle 1. The nozzle opening 6 has a chamfered portion 50, which cuts off a portion of the nozzle opening 6. The chamfered portion 50 has the effect of circumferentially cutting off the powder portion 11 and the forward portion 12 without the powder portion, which selectively forms the process gas unit 60, around the optical channel 3. The chamfered portion 50 reduces the volume of the nozzle opening 6 compared to embodiments without the chamfered portion 50. This ensures that the nozzle opening 6 occupies a smaller installation space. The injection nozzle 1 having the chamfered portion 50 can be used, for example, for coating brake discs. The brake disc may have mounting portions that project axially from the functional surface to be coated. The chamfered portion 50 ensures that the injection nozzle 1 can move flexibly on the functional surface to be coated and move in close proximity to the holder. The chamfered portion 50 is substantially flat and may extend in a plane inclined with respect to the longitudinal direction of the injection nozzle. The chamfered portion 50 represents the boundary surface of the nozzle opening portion 6 where the powder unit 7 is not provided. In the distal region 8, the chamfered portion 50 is located very close to the optical channel 3, so that in the region of the chamfered portion 50, no injector guide 19 or additional injectors are provided on the end face of the injection nozzle 1 facing the workpiece.

[0057] Figure 15 shows a top view of an injection nozzle 1 having a chamfered portion 50. The chamfered portion 50 may extend into the distal region 8 in the form of a through portion 51 over a slotted hole. The through portion 51 defines the orientation of the chamfered portion 50 over the nozzle opening 6. The through portion 51 extends along a straight line or an extended arc on the end face of the injection nozzle 1 facing the workpiece without crossing or touching the slotted hole. The distance of the through portion 51 from the center point 20 of the optical channel 3 is greater than the distance of the corresponding portion of the slotted hole from the center point 20 of the optical channel 3. The distance between the through portion 51 and the outer edge of the slotted hole is selected so that the wall thickness between them ensures sufficient strength and load capacity of the injection nozzle 1.

[0058] The orientation of the through portion 51, and therefore the orientation of the chamfered portion 50 at the nozzle opening 6, can be changed for each different spray nozzle 1 according to their respective applications. For example, the through portion 51 can extend in the forward direction 2. In this case, the through portion 51 extends along the extended portion of the cross-sectional area of ​​the optical channel 3. The through portion 51 therefore extends along the long side of the slotted hole. Alternatively, the through portion 51 can extend, for example, intersecting the forward direction 2. In this case, the through portion 51 extends intersecting the extended portion of the cross-sectional area of ​​the optical channel 3. The through portion 51 therefore extends along the partial circular section of the slotted hole. Furthermore, alternatively, the through portion 51 can extend at an angle to the forward direction 2, for example, located between a path along the forward direction 2 and a path intersecting the forward direction 2. In this case, the through portion 51 extends along the transition section between the long side of the slotted hole and the partial circular section of the slotted hole. The path of the passage portion 51 determines the orientation of the chamfered portion 50.

[0059] In the embodiment shown in Figure 15, the discharge opening 62 is provided above the front of the injection nozzle. From here, the process gas exits the process gas unit 60. In this example, the portion of the nozzle opening 6 cut off by the chamfered portion 50 is entirely derived from the powder portion 11. Therefore, the angle at which the powder portion 11 extends is reduced by the chamfered portion 50, while the angle at which the process gas unit 60 extends remains substantially the same.

[0060] To the extent applicable, all individual features presented in the exemplary embodiments may be combined with and / or substituted for each other without departing from the scope of the invention. [Explanation of symbols]

[0061] 1. Spray nozzle 2 Forward direction 3 optical channels 4. Side surface 5 External structure 6. Nozzle opening 7 Powder Unit 8. Distal region 9. Flange section 10 Proximal region 11 Powder part 12 Forward section 13 Coolant intake 14 Coolant outlet 15 Connecting rings 16 Powder Injector 17 Inlet connection section 18 Outlet connection 19 Injector Guide 20 Center point of optical channels 21 First powder focus 26 Turn angle 30 Cooling Systems 31 Radially inward cooling chamber 32 Transition Section 33 Radially outer cooling chamber 34 Honeycomb structure 40 Absorbent portion 50 Chamfered section 51 Passage section 60 Process Gas Units 61 Process gas section 62 Discharge opening 63 Supply opening 64-way distribution arm 65. First vapor plume 66. Second vapor plume 100 Workpiece 110 laser beams 111 Primary beam 112 Secondary beam 120 Powdered filling material 130 Welding Pools 140 Functional Layers

Claims

1. A jet nozzle (1) for laser deposition welding in the forward direction (2), - An optical channel (3) for guiding at least one laser beam directed toward the workpiece, - A powder unit (7) positioned radially outside the optical channel (3) for guiding at least one powder jet applied to the workpiece, wherein the powder unit (7) forms a powder portion (11) in the circumferential direction around the optical channel (3), - A process gas unit (60) positioned radially outward of the optical channel (3) for guiding a process gas, wherein the process gas unit (60) has a process gas portion (61) in the circumferential direction, The injection nozzle (1) has a process gas portion (61) adjacent to the powder portion (11) at the nozzle opening (6) in the circumferential direction.

2. The injection nozzle (1) according to claim 1, wherein the process gas unit (60) can form an outlet opening (62) on one end face of the injection nozzle (1) from which the process gas can be supplied to the workpiece, and in particular an additional injector for supplying the process gas without a filler material is located in at least one outlet opening (62).

3. The injection nozzle (1) according to claim 1 or 2, wherein the process gas portion (61) extends around the optical channel (3), particularly in an arc shape, in at least a section along the arc of the slotted hole.

4. The injection nozzle (1) according to any one of claims 1 to 3, wherein the process gas portion (61) extends in the circumferential direction around the optical channel (3) over a winding angle (23) of 5° to 180°, particularly 45° to 120°, with respect to the center point (20) of the optical channel (3).

5. The injection nozzle (1) according to any one of claims 1 to 4, wherein the process gas portion (61) and the powder portion (11) together completely surround the optical channel (3) in the circumferential direction.

6. The injection nozzle (1) according to any one of claims 1 to 5, wherein the process gas unit (60) has a supply opening (63) through which the process gas can be supplied to the process gas unit (60), and at least one discharge opening (62) through which the process gas exits the process gas unit (60).

7. The injection nozzle (1) according to claim 6, wherein the process gas unit (60) has a plurality, in particular three, discharge openings (62), each connected to one of the supply openings (63).

8. The injection nozzle (1) according to any one of claims 1 to 7, wherein the process gas portion (61) is formed in the region of the nozzle opening portion (6) facing the forward direction (2).

9. The injection nozzle (1) according to any one of claims 1 to 8, wherein the powder portion (11) has a plurality of injector guides (19), and a powder injector (16) can be inserted into each of them.

10. The injection nozzle (1) according to claim 9, wherein the inner diameter of at least one discharge opening (62) is smaller than the inner diameter of the injector guide (19).

11. The injection nozzle (1) according to claim 9 or 10, wherein a first powder injector is prepared to deliver a first powder mass flow rate, and a second powder injector is prepared to deliver a second powder mass flow rate, wherein the first powder mass flow rate is different from the second powder mass flow rate.

12. The spray nozzle (1) according to any one of claims 1 to 11, wherein the powder portion (11) forms an annular gap segment.

13. The injection nozzle (1) according to any one of claims 1 to 12, wherein the optical channel (3) is adapted to guide a plurality of laser beams, the plurality having a first laser beam as a primary beam (111) and a second laser beam as a secondary beam (112).

14. An injection nozzle (1) according to any one of claims 1 to 13, manufactured by an additive manufacturing process and comprising, in particular, copper or a copper alloy, in particular, a copper-chromium-zirconium alloy.

15. The spray nozzle (1) according to any one of claims 1 to 14, wherein the nozzle opening portion (6) has a chamfered portion (50) thereafter, a part of the nozzle opening portion (6) is cut off, and the chamfered portion (50) is substantially planar and extends in a plane inclined with respect to the longitudinal direction of the spray nozzle (1).

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