Injection nozzle with cooling system

Abstract

The present invention relates to an injection nozzle (1) for laser deposition welding along a supply direction (2), and comprises an external structure (5) comprising an optical channel (3) for guiding at least one laser beam directed onto a workpiece, the external structure (5) comprising an external structure (5) that surrounds the optical channel (3) and extends from a flange portion (9) to a distal region (8), the distal region (8) being formed by a nozzle opening (6) from which the laser beam is ejected, and a cooling system (30) comprising a radially inward cooling chamber (31) and a radially outward cooling chamber (33) which are intended to be passed through the external structure (5).

Description

Technical Field

[0001] The present invention relates to an injection nozzle for laser deposition welding along a supply direction.

Background Art

[0002] Laser deposition welding is used in the fields of repair, coating, and / or joining technology. It can be distinguished 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 brochures DE 10 2011 100 456 A and DE 10 2018 130 798 A1. Another method related to laser deposition welding is known from Chinese Patent Application No. CN 109175372 A. A powder nozzle for a laser processing machine is known from the published patent application DE 10 2017 215841 A1.

[0003] Functional layers can be applied onto a 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 powdery filler material, and subsequent cooling, so that a matrix structure with hard material particles is materially bonded to the material surface. Thus, laser deposition welding engages with the internal material structure of the workpiece and changes it. In certain environments, this can lead to defects in the internal material structure. These can potentially impair the desired increase in load capacity. Since the defects can be of a microscopic nature, they can only be identified with great effort.

[0004] Summary of the Invention Based on known prior art, an object of the present invention is to provide an improved injection nozzle for laser deposition welding along the feed direction. In particular, an object of the present invention is to increase the weld quality of the applied functional layer and the overall weld quality of the workpiece, and to reduce or avoid defects in the weld joint between the powdered filler and the material surface. Defects may be in the form of insufficient fusion between the material surface and the applied functional layer, or between individual applied functional layers. Defects may also be pores, i.e., air inclusions 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 loads. The present invention may also aim to design injection nozzles to ensure reliable and precise laser deposition welding over a very large number of cycles.

[0005] The 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 along the feed direction is proposed, which comprises an optical channel for guiding at least one laser beam directed onto the workpiece. Laser deposition welding can be a method for high-speed laser metal deposition (HS-LMD). The feed 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 feed direction and the corresponding feed motion 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 light source, from which the laser beam is guided to a laser system by an optical fiber cable, which splits the laser beam through a collimator lens, focuses it along the process through a laser optical system, and then directs it into 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 to the workpiece surface through optical channels.

[0007] The injection nozzle has an external structure that encloses the optical channel in at least one section, extending from the flange portion to the distal region, which is formed by the nozzle opening, from which the laser beam is emitted. The external structure may have a powder unit, which may be part of the nozzle opening. The nozzle opening is part of the injection nozzle facing the workpiece. The end portion of the nozzle opening forms the distal region, which is the part of the nozzle opening closest to the workpiece. In the section facing away from the workpiece, the injection nozzle has a proximal region and a flange portion. The proximal region and flange portion are parts of the injection nozzle facing away from the workpiece. The nozzle may be coupled via the flange portion to another component of the laser system, such as a laser optical system or a process unit. The external structure may be a component made from a homogeneous material and may have a hollow channel that forms the optical channel along its longitudinal direction.

[0008] The external structure is equipped with a cooling system having a cooling chamber that is radially inward in at least one section and a cooling chamber that is radially outward in at least one section, both intended to be permeated by a coolant, particularly water. The cooling system enables efficient thermal management of the injection nozzle. Due to the thermal energy input of the laser beam and powder injection, the injection nozzle is subjected to a very high thermal load. In addition to this, there is reflected radiation from the workpiece. The cooling system helps the injection nozzle withstand this high thermal load. The radially inward cooling chamber faces the optical channel, and the radially outward cooling chamber faces the environment. The radially inward cooling chamber can extend concentrically with the optical channel in at least one section. Similarly, the radially outward cooling chamber can extend concentrically with the optical channel in at least one section. The coolant is statically supplied to and removed from the external structure so that heat is continuously dissipated.

[0009] The injection nozzle can therefore provide increased variability in (i) guiding the laser beam, (ii) using powdered filler material, (iii) thermal management, and / or (iv) protecting 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 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.

[0010] In particular, injection nozzles can reduce the occurrence of any fusion deficiency. This is because fusion deficiency can occur when the surface heated by the laser beam, such as the workpiece or a previously welded functional layer, is not sufficiently heated. This underheating may result from keeping the laser power of a single laser beam low to avoid overheating of the powdered filler material. Due to increased versatility in laser beam induction, increased versatility in the application of powdered filler materials, and / or increased versatility in the thermal management of the injection nozzle, the occurrence of fusion deficiency can be reduced or even avoided, particularly by injection nozzles having a cooling system that ensures efficient cooling with radially inward and radially outward cooling chambers capable of cooling multiple process zones.

[0011] In particular, injection nozzles 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 result from the laser power of a single laser beam being set very high to avoid fusion failures due to insufficient heating. Due to increased versatility in laser beam induction, increased versatility in the application of powdered filler materials, and / or increased versatility in the thermal management of the injection nozzle, the occurrence of pores can be reduced or even avoided, in particular, by injection nozzles having a cooling system that ensures efficient cooling by radially inward and radially outward cooling chambers capable of cooling multiple process zones.

[0012] In particular, injection nozzles can also reduce the occurrence of cracks in the welded functional layer. This is because when the temperature gradient between the strongly heated powdered filler and the weakly heated workpiece surface is very large, the shrinkage of the material during cooling creates stress that causes cracking. Cracks may result from the laser power of a single laser beam being set very high to avoid fusion failure due to insufficient heating. Due to increased versatility in laser beam guidance, increased versatility in the application of powdered filler and / or increased versatility in the thermal management of the injection nozzle, crack occurrence can be reduced or even avoided, in particular, by injection nozzles having a cooling system that ensures efficient cooling by radially inward and radially outward cooling chambers capable of cooling multiple process zones.

[0013] In particular, the injection nozzle can also reduce the dissolution of hard material particles, especially carbides, in the matrix material. Powdered filler materials may contain hard material particles, especially carbides, and 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 levels, 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 loaded. Due to the increased diversity of laser beam guidance, the increased diversity of powdered filler material applications, and / or the increased diversity of thermal management of the injection nozzle, the dissolution of hard material particles can be reduced or even avoided, in particular, by injection nozzles having a cooling system that ensures efficient cooling by radially inward and radially outward cooling chambers that can cool multiple process zones.

[0014] 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 fusion defects. Due to increased diversity in laser beam guidance, increased diversity in the application of powdered filler materials, and / or increased diversity in the thermal management of the injection nozzle, the melting of unwanted hard material particles, as well as the propagation of metal vapor plumes, can be reduced or even avoided, in particular, by an injection nozzle having a cooling system that ensures efficient cooling by radially inward and radially outward cooling chambers that can cool multiple process zones.

[0015] The cooling system, by dividing itself into radially inward and radially outward cooling chambers, enables a uniform flow distribution along the periphery of the nozzle opening. The flow may be turbulent. The radially inward and radially outward cooling chambers are designed to provide very low pressure drops, for example, below 0.15 bar. The nozzle opening is efficiently cooled by the cooling system. This prevents the individual injector guides from welding together due to excessive heat generation in the nozzle opening area. The heat in the nozzle opening region is thought to be primarily due to the thermal energy of the laser beam and powdered filler material. Heat may also be due to radiation reflected from the workpiece to the injection nozzle. The heat is reliably dissipated by the cooling system. The improved characteristics of the injection nozzle due to the cooling system enable the aforementioned defect-free welding behavior.

[0016] In one embodiment, the radially outer cooling chamber extends from the distal region to the proximal region adjacent to the flange portion. The radially outer cooling chamber can therefore extend across the entire height of the injection nozzle, excluding the flange portion. Thus, energy is transferred from the injection nozzle to the cooling medium across the entire height of the injection nozzle, which contributes to efficient thermal management.

[0017] In one embodiment, the radially inner cooling chamber is formed at least at the nozzle opening and extends particularly from the distal region to the proximal region adjacent to the flange portion. This enables effective cooling of the nozzle opening. The radially inner cooling chamber can therefore extend across the entire height of the injection nozzle, except for the flange portion. Thus, energy is transferred from the injection nozzle to the cooling medium across the entire height of the injection nozzle, contributing to efficient thermal management. The radially inner cooling chamber may have a bead in the proximal region that differs from the annular gap shape, thereby facilitating the inflow characteristics from the heat intake to the entire radially inner cooling chamber.

[0018] In one embodiment, the radially inner cooling chamber extends concentrically with the optical channel in a cross-sectional area perpendicular to the longitudinal direction of the injection nozzle. In particular, the radially inner cooling chamber extends concentrically with the optical channel over its entire height.

[0019] In one embodiment, the radially inward cooling chamber is a channel that extends circumferentially, at least in the region of the nozzle opening. In particular, the cooling chamber is a circumferential channel from the nozzle opening to the proximal region. Therefore, the thermal energy supplied to the injection nozzle can be dissipated over a wide area.

[0020] In one embodiment, the radially inward cooling chamber and / or radially outward cooling chamber are provided with a cooling structure to increase the surface area. The cooling structure, like the other parts of the injection nozzle, can be manufactured using an additive manufacturing process. This ensures that the cooling medium comes into contact with as much surface area as possible as it is supplied from the distal region to the proximal region and / or returns, thereby facilitating heat dissipation. The cooling structure is optimized to minimize pressure loss of the cooling medium. This is ensured by a uniform, and especially turbulent, flow distribution around the nozzle opening. Since the nozzle opening is primarily a heat-generating region, such ensured efficient heat dissipation from the nozzle opening is particularly useful.

[0021] In one embodiment, the cooling structure is designed in the form of a honeycomb structure, and / or a pin structure, and / or a fin structure. The honeycomb structure may have multiple honeycombs. The individual honeycombs are arranged relative to each other such that the cooling medium is exposed to a substantially constant passage area. The honeycomb structure can be adapted to the geometric conditions of the injection nozzle along the circumferential direction. For example, the shape of the honeycomb may differ when a powder portion is supplied into the nozzle opening compared to when a powder-free supply portion is provided. The pin contour may consist of individual pins having a circular cross-section in particular. This ensures an optimal surface area ratio for optimal heat dissipation. The fin structure may consist of individual fins having an elliptical and / or almond-shaped and / or teardrop-shaped cross-section in particular. This ensures a flow-optimized surface for low pressure loss.

[0022] In one embodiment, a transition section is provided in the distal region from a radially inner cooling chamber to a radially outer cooling chamber. This ensures that the cooling medium flows through the radially inner cooling chamber to the distal region and then merges with the radially outer cooling chamber. The transition section may be annular in the distal region.

[0023] In the embodiment, the external structure includes a powder unit positioned radially outside the optical channel to guide at least one powder jet applied to the workpiece. The powder unit forms a powder portion at the nozzle opening circumferentially around the optical channel, adjacent to a supply portion without the powder unit in the circumferential direction. The supply portion may be oriented in the supply direction, i.e., directed in the direction of the supply. The supply portion may extend along the circumferential direction around the optical channel over a certain angular range. The region in which the supply portion is formed can correlate with the position and orientation of the powder injector that applies the powdery filler to the workpiece. Both the powder portion and the supply portion can form the entire circumference of the nozzle opening around the optical channel. For example, the powder portion may occupy a larger portion than the supply portion. In a plan view, the powder portion and the supply portion may extend in a closed manner along the opening of the optical channel, e.g., an extended opening.

[0024] In one embodiment, the transition from the radially inner cooling chamber to the radially outer cooling chamber is designed as a passage in the supply section. The passage may be the only transition from the radially inner cooling chamber to the radially outer cooling chamber. Therefore, the cooling medium is guided from the annular structure of the radially inner cooling chamber to the local passage, and then guided to the outer cooling chamber, which extends along the entire circumference. This further contributes to efficient thermal management.

[0025] In one embodiment, the radially inner cooling chamber is connected to a coolant inlet, and the radially outer cooling chamber is connected to a coolant outlet. In this case, the coolant inlet to the coolant inlet may be located in the proximal region, and / or the coolant outlet from the coolant outlet may be located in the proximal region. After the coolant inlet, the cooled medium is guided into the radially inner cooling chamber before it reaches the radially outer cooling chamber as an already heated coolant. This allows the nozzle head to be cooled particularly efficiently.

[0026] In one embodiment, the coolant inlet and / or coolant outlet project at least partially radially from the external structure. They can also form an angle with respect to each other. On the one hand, this provides the axial mounting space required by the injection nozzle, and on the other hand, it allows the cooling medium to swirl in the desired manner by radial flow. In this way, the versatility of thermal management can be further considered.

[0027] In one embodiment, the injection nozzle is manufactured by an additive manufacturing process, particularly by powder bed fusion. For this purpose, the injection nozzle may be made from copper or a copper alloy, and more particularly, 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).

[0028] In one embodiment, the nozzle opening includes a chamfer portion formed by cutting off a part of the nozzle opening, the chamfer portion is substantially planar, and extends in a plane inclined with respect to the longitudinal direction of the injection nozzle. The chamfer portion can cut off the powder portion and the supply portion without powder portion in the circumferential direction around the optical channel. The chamfer portion reduces the volume of the nozzle opening compared to an embodiment without chamfer. This means that the nozzle opening occupies a smaller installation space. The injection nozzle having a chamfer portion can be used, for example, to coat a brake disk having a mounting portion protruding axially from a functional surface to be coated. The chamfer portion ensures that the injection nozzle can move flexibly on the functional surface to be coated and can move close to the mounting portion. The chamfer portion can extend into the distal region, such as a through portion on the slot. The through portion defines the orientation of the chamfer portion on the nozzle opening. At the end face of the injection nozzle facing the workpiece, the through portion extends along a straight line or an arc that neither intersects nor contacts the slot. The distance of the through portion from the center point of the optical channel is greater than the distance of the corresponding section of the slot from the center point of the optical channel. The distance between the through portion and the outer edge of the slot is selected such that the wall thickness therebetween ensures sufficient robustness and load capacity of the injection nozzle.

[0029] 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 laser beam is orthogonal to the cross-sectional area. Further, the optical channel can be adapted to guide the shielding gas along the radially outer portion to shield the process zone.

[0030] The features according to the disclosure contribute, partly alone and partly in combination, to overcoming the defects of the laser deposition welding mentioned at the beginning.

Brief Description of the Drawings

[0031] Further preferred embodiments of the present invention will be described in more detail by the following description of the drawings. [Figure 1] A schematic diagram of the injection nozzle during laser deposition welding is shown. [Figure 2] A side view of the injection nozzle is shown. [Figure 3] Figure 2 shows a perspective view of the injection nozzle. [Figure 4] Figure 2 shows the injection nozzle connected to other components. [Figure 5] Figure 2 shows a top view of the distal region of the injection nozzle. [Figure 6] Figure 2 shows a top view of the flange portion of the injection nozzle. [Figure 7] Another perspective view of the injection nozzle from Figure 2 is shown. [Figure 8] Figure 2 shows a perspective cross-sectional view of the injection nozzle. [Figure 9] Another perspective view of the injection nozzle from Figure 2 is shown. [Figure 10] Different diagrams of a cooling system with a pin structure are shown. [Figure 11] This is a top view of the distal region, showing an injection nozzle with a process gas unit. [Figure 12] A side view shows a further embodiment of an injection nozzle having a geometrically adapted nozzle opening. [Figure 13] A top view shows a further embodiment of an injection nozzle having a geometrically adapted nozzle opening. [Modes for carrying out the invention]

[0032] 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.

[0033] Figure 1 shows a jet nozzle 1 for laser deposition welding along a supply direction 2. The supply direction 2 is the direction in which the jet 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 jet nozzle 1, or a superposition of the movement of the workpiece 100 and the jet nozzle 1. The supply direction 2 and the corresponding supply motion 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 outward 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, multiple injector guides 19 (see Figure 3), into which a powder injector 16 (see Figure 4) can be inserted. As an alternative to individual injector guides 19, the powder unit 7 may have powder ring gap channels. The powdered filler material 120 is directed onto the workpiece 100 via the powder unit 7 and the powder injectors 16 located inside it. The laser beam 110 heats the workpiece 100 so that a molten pool 130 is formed on the material surface. In addition, the laser beam 110 heats the powdered filler material 120, which includes hard material particles and matrix material. For this purpose, the laser beam 110 may have reduced core strength. As soon as the molten 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 capacity.

[0034] Figure 2 shows the injection nozzle 1 in a side view with the supply direction 2 oriented out of the drawing plane. The injection nozzle 1 may 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. Following the powder section 11 is a supply section 12 without powder units, which follows circumferentially. The supply 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).

[0035] 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 section 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, followed circumferentially by a supply portion 12 without the powder unit. The supply section 12 is the area of ​​the nozzle opening 6, where the injector guide 19 is not provided, and therefore powdered filler material 120 is not supplied through this section. In one embodiment, the supply section 12 may be formed as a process gas section 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 geometric shape, 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).

[0036] Figure 4 shows the injection nozzle 1 to which additional components are attached. The connecting ring 15 is connected to the flange portion 9 and attaches the injection nozzle 1 to a connecting unit, such as a laser optical system or process adapter. The powder injector 16 is inserted into the injector guide 19 of the powder unit 7. The powdered filler material 120 is transported by the powder injector 16 and applied to the workpiece 100 at a predetermined focus. Individual powder injectors 16 can use different powder focuses with respect to each other. Alternatively, the powder injectors 16 can 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 supply portion 12. The intake connector 17 is also inserted into the coolant intake 13, and the discharge connector 18 is inserted into the coolant discharge port 14. These connect the coolant intake 13 and the coolant discharge port 14 to the coolant circuit.

[0037] 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, which is perpendicular to the longitudinal direction of the injection nozzle 1, is deviated from a circular shape and extends in the supply direction 2. In the distal region 8, the cross-sectional area of ​​the optical channel 3 is designed to be elongated, with the two opposite ends of a rectangular cross-section joined by a partial circular cross-section. Two laser beams, a primary beam 111 and a secondary beam 112, are guided into the optical channel 3. The primary beam 111 and the secondary beam 112 may originally originate from the same optical fiber cable. The supplied laser light can be split into parallel beam bundles via a collimator lens. The beam bundles can be formed from a single laser beam, for example, using a wedge plate. The center points of the primary beam 111 and the secondary beam 112 are located in the supply direction 2 on a line offset from the center point 20 of the optical channel 3.

[0038] In this example, the secondary beam 112 is located ahead of the primary beam 111 in the feed direction 2 and does not interact with the powder's focal 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 are irradiated onto 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, and in particular, there are no defects such as insufficient fusion, no porosity, no cracks, and / or no dissolution of carbides in the matrix material. It is also possible to guide the secondary beam 112 behind the primary beam 111 in the feed 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.

[0039] The primary beam 111 and the secondary beam 112 are positioned in close proximity to each other. The front circular section of the elongated hole in the supply direction 2 is concentric with the secondary beam 112, while the rear circular section of the elongated hole is concentric with the primary beam 111. The center point of the cross-sectional area is eccentric with respect to the center point of the primary beam 111 and the center point of the secondary beam 112. A tertiary beam may also be provided, for example, the secondary beam being positioned in front of the primary beam in the supply direction, and the tertiary beam being positioned behind the primary beam in the supply direction. The individual laser beams are guided without shielding each other, so there is exactly one optical channel 3 with exactly one transverse surface 4, thereby minimizing heat loss.

[0040] In Figure 5, the primary beam 111 is positioned behind the secondary beam 112 in the supply direction 2 without radial offset, and the secondary beam 112 functions to preheat the workpiece. Therefore, 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 performs 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 a powder portion 11 is formed circumferentially around the optical channel 3, and a supply 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 supply portion 12 is formed as the process gas portion 61. The supply portion 12 is formed in the region of the nozzle opening 6 facing the supply direction 2. The powder portion 11 extends along the elongated pores that form the cross-sectional area of ​​the optical channel 3 in the distal region 8. Similar to a circular arc, the powder portion 11 extends around the optical channel 3, particularly along the elongated pore-like arcs of a horseshoe shape. Thus, the powder portion 11 extends in the circumferential direction around the optical channel 3 with a winding angle of less than 360°, particularly 90° to 330°, and even more particularly 180° to 300°, with respect to the center point of the optical channel. This ensures that the powdery packing 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 supply portion 12 form an elongated pore shape when viewed from above. This also helps to reduce or avoid the defects identified at the beginning.

[0041] 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 supply 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 supply direction and at least 2 times larger intersecting the supply 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.

[0042] 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 supply direction 2, the optical channel is extended 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 along the powder portion 11 around the optical channel 3, and the powder portion 11 is adjacent to a supply portion 12 without powder.

[0043] 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 guiding powder injection is not provided within the supply section 12. The injection nozzle 1 has a cooling system 30. For example, a cooling medium such as water is supplied back to the cooling chamber 31 radially inward 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 radial width 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.

[0044] 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 discharge port 14. The transition section 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is located within the supply section 12. The supply section 12 does not have an injector guide 19 for guiding the ejection of the powder beam, so sufficient space is provided for the transition section 32.

[0045] 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. As the cooling medium returns from the distal region 8 to the proximal region 10, it is ensured that it comes into contact with as much surface area as possible to promote heat dissipation. The cooling structure is optimized to minimize pressure loss of the cooling medium. This can be achieved by a honeycomb structure 34, as shown in Figure 8.

[0046] Figure 9 shows the injection nozzle 1 in a further perspective view. The coolant inlet 13 is provided within a proximal region 10 adjacent to the flange portion 9. The radially inner cooling chamber 31 extends annularly from the coolant inlet 13 along the circumferential direction around the optical channel 3. The proximal portion of the radially inner cooling chamber 31 has a bead, from which the radially inner cooling chamber 31 extends to the distal region 8 with a smaller radial width relative to the radially outer cooling chamber 33. In the provided distal transition 32, the cooling medium moves from the radially inner cooling chamber 31 to the radially outer cooling chamber 33. Within the radially outer cooling chamber, the cooling medium travels along a path from the transition 32 to the coolant discharge port 14 provided in the proximal region 10. High heat exchange is ensured because the cooling medium is guided from the proximal coolant inlet 13 through the distal transition 32 and then to the proximal coolant discharge port 14. This is further increased by the fact that the radially outer cooling chamber 33 has an increased surface area.

[0047] Figures 10a, 10b, and 10c show an alternative cooling structure to the honeycomb structure 34 in the form of a pin structure 35, which has multiple pins. The pins protrude from the surface of the radially outer cooling chamber 33. They can be manufactured using an additive manufacturing process. Individual pins may have a radially conical cross-section to ensure a substantially constant passage area as the cooling medium flows through the radially outer cooling chamber 33. This minimizes pressure loss and increases heat exchange. In a continuous row, the individual pins are offset from each other, thereby increasing forced convection. The density of the pins increases toward the distal region 10.

[0048] Figure 11 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 supply 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 injection of powder, 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 supply 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 and directing the process gas towards the workpiece. The process gas portion 61 can prevent undesirable diffusion of the vapor plume and therefore contribute to precise workpiece processing with a robust injection nozzle design. The process gas portion 61 can form at least one, in this example, three discharge openings 62. The discharge openings 62 are formed on one end face of the injection nozzle 1. Additional injectors for supplying process gas can be inserted into each discharge opening 62 without additional material. The inner diameter of the discharge 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 an elongated hole formed by the optical channel 3. Thus, the primary beam 111 and the secondary beam 112 are entirely contained within the beam consisting of the powder injection and the process gas injection.

[0049] Figure 12 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 cutting off the powder portion 11 and the supply portion 12 without the powder portion in the circumferential direction 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 can move in close proximity to the mounting portions. The chamfered portion 50 is substantially planar 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 6 where the powder unit 7 is not provided. In the distal region 8, the chamfered portion 50 is positioned very close to the optical channel 3, and therefore, in the region of the chamfered portion 50, the end face of the injection nozzle 1 facing the workpiece is not provided with an injector guide 19.

[0050] Figure 13 shows a top view of the injection nozzle 1 having a chamfered portion 50. The chamfered portion 50 can extend into the distal region 8, such as a through portion 51 on the elongated hole. The through portion 51 defines the orientation of the chamfered portion 50 on the nozzle opening 6. On the end face of the injection nozzle 1 facing the workpiece, the through portion 51 extends along a straight line or arc that neither intersects nor contacts the elongated 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 elongated hole from the center point 20 of the optical channel 3. The distance between the through portion 51 and the outer edge of the elongated hole is selected so that the wall thickness between them ensures sufficient robustness and load capacity of the injection nozzle 1.

[0051] The orientation of the passage 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 its respective application. For example, the passage portion 51 can extend in the supply direction 2. In this case, the passage portion 51 extends along the extension of the cross-sectional area of ​​the optical channel 3. Therefore, the passage portion 51 extends along the long side of the elongated hole. Alternatively, the passage portion 51 can extend, for example, intersecting the supply direction 2. In this case, the passage portion 51 extends intersecting the extension of the cross-sectional area of ​​the optical channel 3. Therefore, the passage portion 51 extends along the partial circular section of the elongated hole. Furthermore, alternatively, the passage portion 51 can extend at an angle to the supply direction 2, located between a path along the supply direction 2 and a path intersecting the supply direction 2. In this case, the passage portion 51 extends along the transition section between the long side of the elongated hole and the partial circular section of the elongated hole. The path of the passage portion 51 determines the orientation of the chamfered portion 50.

[0052] In the embodiment shown in Figure 13, the discharge opening 62 is provided on the front surface of the injection nozzle. The process gas exits the process gas unit 60 through these discharge openings. In this example, the chamfered portion 50 is such that 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.

[0053] 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]

[0054] 1. Spray nozzle 2 Supply 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 Supply part 13 Coolant intake 14 Coolant discharge port 15 Connecting rings 16 Powder Injector 17. Intake Connection 18 Outlet connection 19 Injector Guide 20 Center point of optical channels 21 First powder focus 30 Cooling Systems 31 Radially inward cooling chamber 32 Transition Section 33 Radially outer cooling chamber 34 Honeycomb Structure 35-pin structure 50 Chamfered section 51 Passage section 60 Process Gas Units 61 Process gas section 62 Discharge opening 100 Workpiece 110 laser beams 111 Primary beam 112 Secondary beam 120 Powdered filling material 130 Melting pool 140 Functional Layers

Claims

1. A jet nozzle (1) for laser deposition welding along the supply direction (2), - An optical channel (3) for guiding at least one laser beam directed onto the workpiece, - An external structure (5) that surrounds the optical channel (3) in at least one section, extends from the flange portion (9) to the distal region (8), the distal region (8) is formed by the nozzle opening portion (6), and the laser beam is emitted from the distal region, The external structure (5) comprises a cooling system (30) having a cooling chamber (31) that is radially inward in at least one section and a cooling chamber (33) that is radially outward in at least one section, and through which a coolant is intended to pass, the injection nozzle (1).

2. The injection nozzle (1) according to claim 1, wherein the radially outer cooling chamber (33) extends from the distal region (8) to the proximal region (10) adjacent to the flange portion (9).

3. The injection nozzle (1) according to claim 1 or 2, wherein the radially inward cooling chamber (31) is formed at least at the nozzle opening (6), and in particular extends from the distal region (8) to the proximal region (10) adjacent to the flange portion (9).

4. The injection nozzle (1) according to any one of claims 1 to 3, wherein the radially inward cooling chamber (31) extends concentrically with the optical channel (3) in a cross-sectional area perpendicular to the longitudinal direction of the injection nozzle (1).

5. The injection nozzle (1) according to any one of claims 1 to 4, wherein the radially inward cooling chamber (31) is a channel that extends circumferentially in at least the region of the nozzle opening (6).

6. The injection nozzle (1) according to any one of claims 1 to 5, wherein the radially inner cooling chamber (31) and / or the outer cooling chamber (33) are equipped with a cooling structure for increasing the surface area.

7. The injection nozzle (1) according to claim 6, wherein the cooling structure is designed in the form of a honeycomb structure (34) and / or a pin structure (35) and / or a fin structure.

8. The injection nozzle (1) according to any one of claims 1 to 7, wherein the transition portion (32) is provided in the distal region (8) from the radially inner cooling chamber (31) to the radially outer cooling chamber (33).

9. The spray nozzle (1) according to any one of claims 1 to 8, wherein in the external structure (5), a powder unit (7) positioned radially outward of the optical channel (3) is formed to guide at least one powder spray applied to a workpiece, the powder unit (7) forms a powder portion (11) at the nozzle opening (6) in the circumferential direction around the optical channel (3), and a supply portion (12) without a powder unit is adjacent to this in the circumferential direction.

10. The injection nozzle (1) according to claim 8 or 9, wherein the transition section (32) is designed as a passage within the supply section (12).

11. The injection nozzle (1) according to any one of claims 1 to 10, wherein the radially inward cooling chamber (31) is connected to a coolant inlet, and the radially outward cooling chamber (33) is connected to a coolant discharge port, in particular, the coolant inlet (13) is positioned in the proximal region (10) for a coolant inlet and / or the coolant discharge port (14) is positioned in the proximal region (10) for a coolant discharge port.

12. The spray nozzle (1) according to claim 11, wherein the coolant inlet (13) and / or the coolant outlet (14) protrude radially from the external structure (5) in at least one section, and in particular the coolant inlet (13) forms an angle with respect to the coolant outlet (14).

13. An injection nozzle (1) according to any one of claims 1 to 12, manufactured by an additive manufacturing process and comprising, in particular, copper or a copper alloy, in particular, a copper-chromium-zirconium alloy.

14. The spray nozzle (1) according to any one of claims 1 to 13, wherein the nozzle opening portion (6) is provided with a chamfered portion (50) formed by cutting off a part of the nozzle opening portion (6), and the chamfered portion (50) is substantially flat and extends in a plane inclined with respect to the longitudinal direction of the spray nozzle (1).

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