Jet nozzle with opposing injector guides

Abstract

The present invention relates to a jet nozzle (1) for laser cladding along a direction of advance (2), comprising a light channel (3) for conducting at least one laser beam that is directed onto a workpiece; and a powder unit (7) located radially outside the light channel (3) for conducting at least one jet of powder to be applied to the workpiece with a first powder focus (21); wherein: the powder unit (7) forms a powder section (11) at a mouth (6) of the nozzle in a circumferential direction about the light channel (3), said powder section having a plurality of injector guides (19) into preferably each of which one powder injector (16) can be inserted; and wherein a first injector guide (70) lies substantially opposite a second injector guide (71) in relation to the first powder focus (21).

Description

[0001] Jet nozzle with opposing injector guides

[0002] Technical area

[0003] The present invention relates to a jet nozzle for laser cladding along a feed direction and a method for laser cladding.

[0004] State of the art

[0005] Laser cladding is used in repair, coating, and / or joining technology. A distinction can be made between conventional laser cladding (laser metal deposition (LMD), direct metal deposition (DMD), or direct energy deposition (DED)) and so-called high-speed laser cladding (HS-LMD or extremely high-speed laser cladding (EHLA)). HS-LMD processes are described, for example, in published patent applications DE 102011 100456 A and DE 102018 130 798 A1. Another laser cladding process is known from the Chinese patent application CN 109175372 A.

[0006] Laser cladding can be used to apply a functional layer to a workpiece. This layer generally increases the load-bearing capacity of the workpiece processed using laser cladding compared to an unmachined workpiece. The functional layer can serve, for example, as a wear-resistant layer. The application of the functional layer is based on melting a workpiece surface, applying a powdered filler material, and subsequent cooling, so that a matrix structure with hard material particles is firmly bonded to the material surface. Laser cladding thus intervenes in the internal material structure of the workpiece and changes it. This can potentially result in deficiencies in the internal material structure. These can impair the desired increase in load-bearing capacity. The deficiencies can be microscopic in nature, which is why they are only identifiable with great effort.

[0007] Description of the invention Starting from the known prior art, it is an object of the present invention to provide an improved jet nozzle and an improved method for laser deposition welding along a feed direction. The invention aims in particular to increase the weld quality of an applied functional layer and of the workpiece as a whole and to reduce or avoid deficiencies in a weld joint between a powdered filler material and a material surface. Thus, the jet nozzle can be intended to enable reliable application of the functional layer in the region of a hub cup of a rotationally symmetrical component, such as a brake disc, especially at a lateral angle of attack of greater than 5° between the jet nozzle and the component.The lateral angle of attack describes the inclination of the blasting nozzle relative to a workpiece about a feed axis along which the feed direction runs. The deficiencies to be avoided can be a wavy functional layer that deviates from the desired smooth functional layer and can result in particular from filler material that is improperly directed onto the component surface. The deficiencies can also be bonding defects between the material surface and the applied functional layer or between individual applied functional layers. The deficiencies can also be pores, i.e. air inclusions, that occur within the applied functional layer or between the applied functional layer and the material surface. Pores can occur more frequently, especially if the material surface is a cast material.The deficiencies may also include cracks, particularly those running vertically to the material surface within the applied functional layer. The deficiencies may also result from powder particles, particularly carbides, of the powdered filler material dissolving in a matrix material of the powdered filler material, leading to embrittlement of the matrix material. The invention further aims, in particular, to provide a reliable blasting nozzle that is resistant to thermal stress. The invention may further aim to design the blasting nozzle in such a way that it ensures reliable and precise laser cladding over very high cycle numbers.

[0008] The problem is solved by a jet nozzle having the features of claim 1. Advantageous further developments emerge from the subclaims, the description, and the figures.

[0009] Accordingly, a beam nozzle for laser material deposition along a feed direction is proposed, which has a light channel for guiding at least one laser beam directed at a workpiece. Laser material deposition can be a process for high-speed laser material deposition (HS-LMD). The feed direction is the direction along which the beam nozzle moves relative to the workpiece. It can result from a movement, in particular a rotational movement, of the workpiece, from a movement of the beam nozzle, or from a superposition of both movements. The feed direction and the correlating feed movement can be constant throughout the process. Alternatively, they can vary with the respective process stage. The workpiece can be a rotationally symmetrical workpiece, such as a brake disc, a hydraulic cylinder, a printing roller, or a plain bearing.The laser beam can pass through the light channel. It can be provided by a laser source, from which the laser beam is guided via a fiber optic cable to a laser system that splits the laser beam using a collimating lens and focuses it using laser optics for the specific process before it enters the jet nozzle. The light channel can be a hollow channel that runs longitudinally through the entire jet nozzle. In addition to the laser beam, a process gas can also be guided to the workpiece surface through the light channel.

[0010] The blasting nozzle further comprises a powder unit arranged radially outside the light channel for guiding at least one powder jet, which is to be applied to the workpiece with at least a first powder focus. The powder unit can be arranged radially outside the light channel, starting from the longitudinal direction of the blasting nozzle, and can be part of an external structure that encloses the light channel. The powder jet can guide at least one powdered filler material consisting of hard material particles, in particular carbides, and a matrix material. The powder unit can be the part of the blasting nozzle that is intended to guide the powdered filler material directly or indirectly. The powder jet is fully or partially focused on the first powder focus. The first powder focus is the point to which the powder unit directs the powder jet. The first powder focus can be eccentric to a center point of the light channel.

[0011] At a nozzle mouth, the powder unit forms a powder section in a circumferential direction around the light channel, which section has a plurality of injector guides, into each of which a powder injector can be inserted, wherein a first injector guide is located substantially opposite a second injector guide with respect to the first powder focus. An injector guide can serve as a receptacle for a powder injector. Alternatively, the injector guides themselves represent injector openings through which the powder material is guided through the blasting nozzle without the need for additional powder injectors. The powder unit can be part of the nozzle mouth. The nozzle mouth is the part of the blasting nozzle facing the workpiece. The end section of the nozzle mouth has a distal region. This represents the part of the nozzle mouth that is closest to the workpiece. At the section facing away from the workpiece, the blasting nozzle has a proximal region and a flange section.The proximal region and the flange section are the part of the jet nozzle facing away from the workpiece. The nozzle can be coupled to another component of the laser system, such as laser optics or a processing unit, via the flange section. The powder section can form a section of the circumference of the nozzle mouth around the light channel. For example, the powder section can make up the larger part of the circumference of the nozzle mouth. The injector guides can be cylindrical or conical through-openings in the area of ​​the nozzle mouth, into each of which a powder injector can be inserted. The injector guides can be incorporated into the nozzle mouth by machining. However, they are preferably already provided during additive manufacturing of the jet nozzle. The injector guides can be adapted to the powder injector to be used.The first injector guide can be point-mirrored to the second injector guide at the first powder focus. It can also be point-mirrored by a deviation of 5° to 15° along the circumferential direction around the light channel. The jet nozzle can have a lateral angle of attack. The lateral angle of attack describes the inclination of the jet nozzle relative to a workpiece about a feed axis along which the feed direction runs. The lateral angle of attack therefore runs sideways to the feed direction. The jet nozzle can also have a posterior angle of attack. The posterior angle of attack describes the inclination of the jet nozzle opposite the feed direction. The posterior angle of attack therefore runs in or opposite to the feed direction. The jet nozzle can have at least two injector guides that lie opposite one another. In particular, it can have four or more injector guides.

[0012] The jet nozzle can thus provide increased variability in (i) laser beam guidance, (ii) the application of a powdered filler material, (iii) thermal management, and (iv) the protection of the laser system including the jet nozzle. It enables the provision of multiple independent process zones with high precision. The process zones can be divided into zones for laser cladding and zones for pre- and / or post-processing. In the laser cladding zones, an interaction takes place between at least one laser beam and a powdered filler material. The pre- and / or post-processing can be cleaning the material surface, preheating the material surface before the powdered filler material is applied, post-heating the material surface after the powdered filler material has been applied, or a combination thereof.During pre- and / or post-processing, the laser beam can strike the workpiece without interacting with the powdered filler material. The independent process zones can increase the weld quality and thus the resilience of the applied functional layer, especially the wear-resistant layer, and the workpiece as a whole. An additional process gas can stabilize the process zones and increase the precision of the laser cladding as well as the service life of the jet nozzle. Furthermore, the opposing injector guides can help ensure that the functional layer is applied smoothly, thus free of waviness, to the workpiece surface, and increase the stability of the jet nozzle.

[0013] In particular, the blasting nozzle can reduce the occurrence of fusion defects. Fusion defects can occur when the surface heated by the laser beam, such as the workpiece or a previously welded functional layer, has not been sufficiently heated. This insufficient heating can be the result of the laser power of a single laser beam being kept low to prevent overheating of the powdered filler material. The increased variability of the laser beam guidance, the increased variability of the application of a powdered filler material, and / or the increased variability of the heat management of the blasting nozzle can reduce or even prevent the occurrence of fusion defects, particularly because the opposing injector guides enable balanced application of different powder jet streams.

[0014] In particular, the blasting nozzle can reduce the occurrence of pores between the welded functional layer and the surface heated by the laser beam. Pores can occur when lamellae in the workpiece, especially graphite lamellae, evaporate due to the laser radiation. Pores can also occur if the surface to be machined contains contaminants, for example, caused by oils, greases, cooling lubricants, or oxides, which cannot be completely removed by the welding process. The undesired evaporation of contaminants can be the result of the laser power of an individual laser beam being set so high that fusion defects due to insufficient heating can be avoided.Due to the increased variability of the laser beam guidance, the increased variability of the application of a powdered filler material and / or the increased variability of the heat management of the blasting nozzle, the occurrence of pores can be reduced or even avoided, in particular because the opposing injector guides enable a balanced application of different streams of the powder jet.

[0015] In particular, the blasting nozzle can reduce the occurrence of cracks in the welded functional layer. Cracks can occur when the temperature gradient between the highly heated powdered filler material and the less heated workpiece surface is so strong that material shrinkage occurring during cooling leads to crack-causing stresses. Crack formation can be the result of setting the laser power of a single laser beam so high that fusion defects due to insufficient heating can be avoided.Due to the increased variability of the laser beam guidance, the increased variability of the application of a powdered filler material and / or the increased variability of the heat management of the blasting nozzle, the occurrence of cracks can be reduced or even avoided, in particular because the opposing injector guides enable a balanced application of different streams of the powder jet.

[0016] Furthermore, the blasting nozzle can particularly reduce the dissolution of hard material particles, in particular carbides, in the matrix material. The powdered filler material can comprise hard material particles, in particular carbides, and a matrix material. The hard material particles should be present undissolved in the welded functional layer in order to increase the load-bearing capacity of the functional layer. However, hard material particles can dissolve if the powdered filler material is exposed to an excessively high irradiation intensity, causing the hard material particles to melt. Dissolved hard material particles cause the welded functional layer to become brittle because the matrix material is less ductile, meaning that stresses arising, for example, from shrinkage during cooling or loading of the workpiece cannot be absorbed by the matrix material.Due to the increased variability of the laser beam guidance, the increased variability of the application of a powdered filler material and / or the increased variability of the heat management of the blasting nozzle, the dissolution of hard material particles can be reduced or even avoided, in particular because the opposing injector guides enable a balanced application of different streams of the powder jet.

[0017] In particular, the blasting nozzle can prevent powder particles from adhering to the nozzle orifice. Due to the high process heat, reflected laser radiation and / or metal vapor flare can cause filler material to adhere or even fuse to the nozzle orifice, disrupting the gas and powder flows and subsequently impairing the process outcome. Metal vapor flare is a result of the partial evaporation of the material during laser cladding. It can lead to scattering and / or absorption of laser radiation and subsequently impair preheating of the workpiece. This can further promote the formation of fusion defects.Due to the increased variability of the laser beam guidance, the increased variability of the application of a powdered filler material and / or the increased variability of the heat management of the blasting nozzle, the undesired dissolution of hard material particles as well as the propagation of the metal vapor flare can be reduced or even avoided, in particular because the opposing injector guides enable a balanced application of different streams of the powder jet.

[0018] The opposing injector guides reduce or prevent a wavy application of the functional layer, which deviates from the desired smooth functional layer. This waviness can result from parameter tolerances. The fact that the injector guides, and consequently the powder injectors arranged therein, are positioned at least approximately in pairs opposite one another ensures fluidic compensation of the individual powder jet streams during the application of the functional layer. Furthermore, the kinematic stability of the jet nozzle is increased by the balancing element created by the opposing injector guides. Furthermore, the jet nozzle contributes to increasing the process window within which process-optimized application of the functional layer is possible by reducing the influence of waviness caused by fluctuations in laser power, nozzle spacing, and / or the conveying and / or nozzle gas.The powder caustic has a long expansion range in the beam direction with an approximately constant powder focus diameter. This helps prevent coating fluctuations and, in particular, waviness.

[0019] In one embodiment, the substantially opposite injector guides are point-mirrored at the first powder focus, so that two of the plurality of injector guides are opposite each other relative to the center of the light channel. They therefore have a geometrically determined position relative to each other. This further contributes to increasing the kinematic stability of the jet nozzle and further expanding the corresponding process window.

[0020] In one embodiment, the plurality of injector guides is an odd number, with a rear injector guide, which is located at the front in the feed direction, being the only one of the plurality of injector guides not having an opposing injector guide. Relative to a center axis of the jet nozzle, the rear injector guide is arranged centrally, thus intersecting the center axis. Therefore, the powder jet emerging from it does not cause any imbalance relative to the center axis and does not require an opposing injector guide. In an alternative embodiment, the plurality of injector guides is an even number, so that each injector guide has an opposing injector guide. This ensures extremely smooth running of the jet nozzle during processing, which further contributes to the smooth surface of the functional layer.

[0021] In one embodiment, in a plane to which the feed direction runs orthogonally, the first injector guide and / or the second injector guide are inclined relative to a longitudinal axis of the light channel, preferably by an injector angle of between 10° and 25°. The individual injector guides can run in different directions. Preferably, however, none of the directions is perpendicular to the feed direction. Thus, the blasting nozzle preferably has no injector guides and consequently no powder injectors that are aligned perpendicular to the feed direction, i.e., the tangential feed. The properties of the functional layer can be adapted to suit the process by the inclination of the injector guides and the resulting injector angles. A longitudinal axis of the light channel, along which the laser beam runs, can be inclined in different directions relative to a normal to the workpiece surface.The laser beam is thus directed non-orthogonally toward the workpiece, for example, tilted by the posterior angle of attack, to selectively capture reflected radiation via the absorption section. Furthermore, an inclination to the lateral angle of attack can contribute to the geometric coating of the functional layer right up to the so-called hub cap of a brake disc. The hub cap can represent an interfering contour, which can cause a collision if the nozzle is aligned orthogonally to the brake disc surface.

[0022] In one embodiment, each of the plurality of injector guides is aligned with the first powder focus, with the first powder focus being located on a longitudinal axis of the light channel along which the laser beam travels. Accordingly, the powder injectors deliver their respective stream to the same location. The jet nozzle thus enables the powder jet to be applied to the workpiece surface at the same location, ensuring the application of a high-quality functional layer within a short period of time. The first powder focus can be located, for example, centrally in a circular opening of the light channel or eccentrically in an elongated opening. The injector guides, or powder injectors inserted therein, can have a common focus or focus area, for example, on a laser secondary symmetry axis.

[0023] In one embodiment, the plurality of injector guides is aligned, for a first part, with the first powder focus and, for a second part, with the first powder focus and the second powder focus running along the feed direction and thus forming a focus line. The injector guides thus form two powder foci, which promotes uniform application of the functional layer along the feed direction. Those injector guides arranged in the region of the first powder focus can be aligned with the first powder focus, and those arranged in the region of the second powder focus can be aligned with the second powder focus. This ensures spatial and functional separation of the individual injector guides, which further promotes the fluidic properties of the jet nozzle.In one embodiment, a first powder injector is inserted into the first injector guide and prepared to convey a first powder mass flow, and a second powder injector is inserted into the second injector guide and prepared to convey a second powder mass flow, wherein the first powder mass flow differs from the second powder mass flow. The first powder injector can be provided opposite the second powder injector. The first powder injector can be arranged such that it interacts with a primary beam of the laser beam. The second powder injector can be arranged such that it interacts with a secondary beam of the laser beam. The primary beam and the secondary beam can be identical to one another or transport different energies.The provision of the first powder mass flow and the second powder mass flow enables the blasting nozzle to implement more than one process zone, which further contributes to increased variability of the blasting nozzle. In particular, the first powder mass flow delivers a different powder than the second powder mass flow. This allows a functional layer with variable materials to be applied to the workpiece. Alternatively, the first powder mass flow and the second powder mass flow can direct the same powder onto the workpiece. Adapting the powder mass flow to the respective injectors to be supplied further contributes to increased variability.

[0024] In one embodiment, a cross-sectional area of ​​the light channel extending orthogonally to the longitudinal direction of the jet nozzle is elongated in the feed direction, deviating from a circular shape, and the powder section extends along an elongated hole arc, in particular in a horseshoe shape, around the light channel. Analogous to a circular arc, the elongated hole arc represents a line surrounding the elongated hole in a sector. The remaining part of the elongated hole, which is not encompassed by the elongated hole arc along which the powder section extends, can be filled by the feed section. The powder section can extend at least partially along the two opposite, straight ends of the elongated hole and the partial circular section located therebetween, to form the horseshoe shape. This further contributes to the possibility of providing more than one process zone.At least one laser beam, in particular at least one circular laser beam and / or one oval laser beam, can be guided along the extended cross-sectional area of ​​the light channel in such a way that more than one process zone is formed. This promotes the welding behavior and reduces deficiencies in the weld joint, in particular the occurrence of fusion defects, pores, cracks, and / or the dissolution of carbides in the matrix material, and increases the load-bearing capacity of the applied functional layer. Thus, the melting behavior, the powder jet behavior, the cohesive bond, and the cooling behavior can be variably adapted to the respective application and the prevailing material properties and process parameters.In one embodiment, the powder section is composed of a first powder section and a second powder section, and the first powder section is separated from the second powder section by a powder section gap. The first and second powder sections can efficiently implement the opposing injector guides. Each injector guide in the first powder section can have an opposing, corresponding injector guide in the second powder section. The sum of the angles between the first powder section and the second powder section can form a wrap angle. If this reaches certain angle ranges, as listed below, this angle range is composed of the sum of the angle section of the first powder section and the angle section of the second powder section in the embodiment in which the powder section is composed of the first and second powder sections.

[0025] In one embodiment, the powder section extends in the circumferential direction around the light channel at a wrap angle of between 45° and 330°, in particular between 90° and 300°, more particularly between 180° and 300°, relative to a center point of the light channel. The wrap angle can be optimized such that each injector guide can have an opposite injector guide. Thus, the powder section can extend around the light channel over a larger section than the feed section. This ensures satisfactory powder supply through the powder unit and, in particular, the injectors arranged therein. Precise adaptation of the powder section and the feed section to the respective process conditions enables efficient welding behavior without deficiencies.In particular, if the nozzle mouth has a bevel that cuts off part of the nozzle mouth, the wrap angle of the powder section is between 90° and 180°. If the nozzle mouth has no bevel, the nozzle mouth is preferably above 180°. In the embodiment in which the powder section is composed of a first powder section and a second powder section, the wrap angle represents the sum of the angles of the first powder section and the second powder section.

[0026] In one embodiment, the light channel is adapted to guide a plurality of laser beams, wherein the plurality has a first laser beam as the primary beam and a second laser beam as the secondary beam. The primary beam and the secondary beam can originate from the same fiber optic cable. A provided laser light can be split into a parallel beam bundle using a collimating lens. The beam bundle can, for example, form the primary beam and the secondary beam from a single laser beam using a wedge plate. In this case, the primary beam and the secondary beam can have the same wavelength and carry the same energy. Alternatively, the primary beam and the secondary beam can differ in terms of their wavelength and energy. The respective centers of the primary beam and the secondary beam can be offset in a line from a center of the light channel in the feed direction.The provision of a plurality of laser beams facilitates the reliable implementation of several process zones.

[0027] In one embodiment, a powder unit-free feed section adjoins the powder section in the circumferential direction and is formed in a region of the nozzle mouth facing the feed direction. The powder section and the feed section can together form the entire circumference of the nozzle mouth around the light channel. For example, the powder section can make up the larger part than the feed section. In plan view, the powder section and the feed section can run closed along an opening of the light channel. The region of the nozzle mouth facing the feed direction is provided in a plan view at the end of the nozzle that is close to the feed direction. One end face of the feed section points in the direction of the workpiece. The feed section can extend along the circumferential direction around the light channel in an angular range.The angular range of the feed section can be smaller than the angular range of the powder section. The area in which the feed section is formed can correlate with the position and orientation of the injector guides and the powder injectors that apply the powdered filler material to the workpiece. Dividing the feed section into a powder section and a feed section can also create a gap in the powder caustic, further contributing to the different process zones. Dividing the feed section into a powder section and a feed section enables welding behavior without the aforementioned deficiencies.

[0028] In one embodiment, a process gas unit for guiding a process gas is arranged radially outside the light channel, wherein the process gas unit forms a process gas section in the circumferential direction, which occupies the feed section. The process gas unit can be located radially outside the light channel, starting from the longitudinal direction of the jet nozzle, and can be part of the external structure that surrounds the light channel. The process gas can have a positive influence on the powder causticity and the workpiece processing caused by it. The process gas unit can be the part of the jet nozzle that is intended to guide the process gas directly or indirectly. The process gas unit can have additional injector guides into which additional injectors can be inserted. It can also have an annular gap within which the process gas is guided. At the nozzle mouth, the process gas unit forms the process gas section in a circumferential direction around the light channel.The process gas unit can be part of the nozzle mouth. In plan view, the process gas section can run at least partially along the opening of the light channel. The process gas section can be the part of the process gas unit from which the process gas exits the jet nozzle. The process gas section can adjoin the powder section at the nozzle mouth in the circumferential direction. Thus, the process gas section can be directly adjacent to the powder section in the circumferential direction. In this way, the process gas can have a stabilizing effect on the powder caustic and the ongoing laser deposition welding. The process gas section can adjoin the powder section in such a way that a transition occurs in the circumferential direction such that an interior is separated from the process gas section and the powder section is separated from an exterior. The separation can be such that as little fluid as possible is exchanged between the interior and the exterior.This can contribute to the stabilization of the process zones and simultaneously prevent the powder particles from adhering to one end face of the blasting nozzle, thus increasing the service life of the blasting nozzle.

[0029] In one embodiment, the jet nozzle is manufactured using an additive manufacturing process, in particular powder bed melting. For this purpose, the jet nozzle can be made of copper or a copper alloy, in particular 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. In powder bed melting, the material to be processed is in powder form. A laser beam heats the powder along the intended geometry, liquefying the powder and bonding it together. Powder bed melting can be implemented, for example, as selective laser melting ("SLM") or selective laser sintering ("SLS"). The jet nozzle can be made of a non-ferromagnetic and / or non-ferromagnetizable material.

[0030] In one embodiment, the nozzle mouth has a bevel by which a portion of the nozzle mouth is cut off, wherein the bevel is essentially flat and runs in a plane that is inclined with respect to the longitudinal direction of the jet nozzle. The bevel can cut off the powder section and the feed section free of powder sections or the process gas section in the circumferential direction around the light channel. The bevel reduces the volume of the nozzle mouth compared to the embodiment in which no bevel is provided. Thus, the nozzle mouth takes up less installation space. The jet nozzle with the bevel can be used, for example, to coat a brake disc that has a receptacle, i.e. a hub cap, that protrudes axially relative to the functional surface to be coated.The bevel ensures that the jet nozzle can move flexibly over the functional surface to be coated and can be moved close to the holder. The bevel can run in the distal area like a passante on the elongated hole or the circular opening. The passante defines the orientation of the bevel at the nozzle mouth. The passante runs on the end face of the jet nozzle facing the workpiece along a straight line or an arc that neither intersects nor touches the elongated hole. The distance of the passante from the center of the light channel is greater than the distance of the corresponding section of the elongated hole from the center of the light channel. The distance between the passante and an outer edge of the elongated hole is selected such that the wall thickness in between ensures sufficient strength and resilience of the jet nozzle.The nozzle orifice can also have two bevels arranged symmetrically at the nozzle orifice. In particular, the bevel is provided on the side of the nozzle orifice facing the hub cap in order to increase the lateral angle of attack of the jet nozzle relative to the perpendicular to the workpiece surface.

[0031] In one embodiment, the process gas unit forms at least one outlet opening on an end face of the jet nozzle, from which the process gas can be guided to the workpiece, wherein an additional injector for supplying the process gas without additional material is arranged in particular in the at least one outlet opening. The outlet opening can be designed on the end face in such a way that the area to which hard material particles can adhere is minimized. The process gas guided from the outlet opening can be supported by the process gas guided within the light channel. An additional injector can be arranged in each outlet opening. The additional injector differs from the injectors arranged in the injector guides of the powder unit. The latter transport the hard material particles to the workpiece surface, the former transport the process gas.

[0032] In one embodiment, the process gas section extends at least partially along a slotted hole arc, in particular in an arc shape, around the light channel. Analogous to a circular arc, the slotted hole arc represents a line surrounding the slotted hole in a sector. The remaining part of the slotted hole, which is not encompassed by the slotted hole arc along which the process gas section extends, can be filled by the powder section. The process gas section can extend at least partially along a partial circle section, in particular the partial circle section that lies at the front in the feed direction, to form the arc shape. This further contributes to stabilizing the laser beam guidance and / or the powder caustic.

[0033] In one embodiment, the process gas section extends circumferentially around the light channel at a wrap angle of between 5° and 180°, in particular between 45° and 120°, relative to a center point of the light channel. Thus, the process gas section can extend around the light channel for a smaller distance than the powder section. This ensures satisfactory powder supply through the powder unit, and in particular the injectors arranged therein, while avoiding adhesion or the spread of the vapor flare. Precise adaptation of the powder section and the process gas section to the respective process conditions enables efficient welding behavior without deficiencies.

[0034] In one embodiment, the process gas section and the powder section together completely surround the light channel in the circumferential direction, i.e., by 360°. The beams emerging from the process gas section and the powder section can thus separate an interior, which forms within the beams, from an exterior, which forms outside the beams. The metal vapor flare, also called vapor flare, resulting from the interaction of the powder particles with the laser beam, cannot thus escape from the interior, preventing undesirable interaction of the vapor flare with the workpiece.

[0035] In one embodiment, an end face of the jet nozzle or the end face from the above embodiment runs at an angle relative to the longitudinal axis of the light channel along which the laser beam runs, such that the end face is intended to run essentially plane-parallel to a workpiece surface. Thus, a distance from the nozzle mouth to the workpiece can be increased with an angled run. This reduces the thermal load on the nozzle mouth. In addition, the angled end face enables improved shielding of the workpiece with the shielding gas. This is because the plane-parallel surface of the end face enables a shielding gas flow to emerge orthogonally to the workpiece. In one embodiment, the jet nozzle is adapted to guide the laser beam along the longitudinal direction of the jet nozzle such that the at least one laser beam runs orthogonally to the cross-sectional area.Furthermore, the light channel can be adapted to guide a protective gas at a radially outer section to shield a process zone.

[0036] In one embodiment, the disclosure further relates to a system comprising a blasting nozzle according to the disclosure and a workpiece. The blasting nozzle is inclined about a feed axis, along which the feed direction runs, in order to form a lateral angle of incidence with respect to the workpiece, such that, in a plane to which the feed direction runs orthogonally, a longitudinal axis of the light channel, along which the laser beam runs, deviates from a normal of a workpiece surface of the workpiece. The lateral inclination can be realized by a relative movement of the blasting nozzle to the workpiece or of the workpiece to the blasting nozzle. For example, a workpiece support can be inclined with respect to the blasting nozzle. The lateral inclination can be selected such that the fluidic compensation of the individual streams of the powder jet is optimized during application of the functional layer. The system can comprise powder injectors. A powder injector can be inserted in each injector guide.In particular, the jet nozzle and / or the powder injectors consist of a non-ferromagnetic material or a non-ferromagnetizable material.

[0037] In one embodiment, the lateral angle of attack is between 2° and 45°, in particular between 5° and 30°, and more particularly between 10° and 25°. At these angles of attack, a smooth functional layer free of waviness can be efficiently realized. Thus, with the opposing arrangement of the injector guides, these angles of attack further contribute to avoiding deficiencies in the functional layer. It has also been found that at these angles of attack, an ideal compromise is achieved between the absorption of reflected radiation via the jet nozzle and the welding behavior of laser deposition welding.

[0038] In one embodiment, at least one, in particular each, of the plurality of injector guides, in particular the first injector guide and / or the second injector guide, is inclined relative to the longitudinal axis of the light channel in a plane to which the feed direction is orthogonal, preferably inclined by an injector angle between 10° and 25°, wherein the sum of the angles of the lateral angle of incidence and the injector angle is such that an injector guide inclined towards the workpiece encloses a workpiece angle of a maximum of 30°, in particular a maximum of 45°, and more particularly a maximum of 50°, with the workpiece. The sum of the lateral angle of incidence and the injector angle means that the injector guide inclined towards the workpiece is at a later angle to the workpiece than other injector guides. If the material angle of the injector guide inclined towards the workpiece is too acute, the functional layer applied by that injector may suffer.In this embodiment, the workpiece angle should therefore not be less than 30°. In particular, the lateral angle of attack and the injector angle are coordinated in such a way that the workpiece angle is not exceeded. This allows for an optimal balance between a high-quality functional layer, a functional layer applied close to the hub cup, and efficient machining time.

[0039] The invention further relates to a method for laser material deposition along a feed direction, in particular by means of a jet nozzle or a system according to this disclosure. The method comprises the step of aligning the jet nozzle with a workpiece. As soon as the jet nozzle is aligned with the workpiece, the laser material deposition process can begin. The method further comprises the step of inclining the jet nozzle about a feed axis along which the feed direction runs, such that the jet nozzle forms a lateral angle of incidence of less than 90° with respect to the workpiece in a plane to which the feed direction runs orthogonally. This ensures that the jet nozzle can be brought close to a hub cup, for example.In particular, in combination with the jet nozzle according to the disclosure and the opposing injectors, the process is suitable for realizing a smooth and large-area functional layer on brake discs with a hub cup.

[0040] In one embodiment of the method, the jet nozzle is tilted such that an injector guide inclined toward the workpiece forms a workpiece angle of a maximum of 30°, in particular a maximum of 45°, and more particularly a maximum of 50°. If the material angle of the injector guide inclined toward the workpiece is too acute, the functional layer applied by that injector may suffer. In this embodiment, the workpiece angle should therefore not be less than 30°. In this way, an optimal balance between a high-quality functional layer, a functional layer applied close to a hub cup, and efficient processing time can be achieved.

[0041] The features disclosed contribute, partly individually and partly in combination, to overcoming the deficiencies in laser cladding mentioned at the outset.

[0042] Short description of the characters

[0043] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. In the figures:

[0044] Figure 1 is a schematic view of a jet nozzle in laser cladding;

[0045] Figure 2 shows a jet nozzle in a side view;

[0046] Figure 3 shows the jet nozzle from Figure 2 in a perspective view;

[0047] Figure 4 shows the jet nozzle from Figure 2 connected to other components;

[0048] Figure 5 shows the jet nozzle from Figure 2 in a plan view of a distal region;

[0049] Figure 6 shows the jet nozzle from Figure 2 in a plan view of a flange section;

[0050] Figure 7 is a further perspective view of the jet nozzle from Figure 2;

[0051] Figure 8 is a perspective sectional view of the jet nozzle of Figure 2;

[0052] Figure 9 shows the jet nozzle in a further embodiment in a plan view of a distal region; Figure 10 shows the jet nozzle with a process gas unit in a plan view of the distal region;

[0053] Figure 11 is a further perspective sectional view of the jet nozzle with an angled end face;

[0054] Figure 12 shows a further embodiment of the jet nozzle with a geometrically adapted nozzle mouth in a side view; and

[0055] Figure 13 shows a further embodiment of the jet nozzle with a first powder section and a second powder section;

[0056] Figure 14 shows the embodiment of Figure 13 in a plan view;

[0057] Figure 15 shows a further embodiment of the jet nozzle with a first powder section and a second powder section;

[0058] Figure 16 shows the embodiment of Figure 15 in a plan view; and

[0059] Figure 17 shows a jet nozzle with a bevel that has been moved towards the hub cap of a brake disc.

[0060] Detailed description of preferred embodiments

[0061] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0062] Figure 1 shows a jet nozzle 1 for laser material deposition along a feed direction 2. The feed direction 2 is the direction along which the jet nozzle 1 moves relative to a workpiece 100. It can result from a movement, in particular a rotational movement, of the workpiece 100, from a movement of the jet nozzle 1, or from a superposition of a movement of the workpiece 100 and the jet nozzle 1. The feed direction 2 and the correlating feed movement can be constant throughout the process. Alternatively, they can vary with the respective process stage. The workpiece 100 can be a rotationally symmetrical workpiece, such as a brake disc, a hydraulic cylinder, a printing roller, or a plain bearing. At least one laser beam 110 emerges from a light channel 3 with a lateral surface 4.The light channel 3 can also be adapted to guide a process protective gas 150 at a radially outer section to shield a process zone and prevent oxidation. The light channel 3 is surrounded by an outer structure 5 having a nozzle mouth 6, which in turn contains a powder unit 7. The powder unit 7 can, for example, have a plurality of injector guides 19 (see Figure 3), into each of which a powder injector 16 (see Figure 4) can be inserted. As an alternative to the individual injector guides 19, the powder unit 7 can have a powder annular gap channel. A powdery filler material 120 is directed onto the workpiece 100 via the powder unit 7 and the powder injectors 16 arranged therein. The laser beam 110 heats the workpiece 100 such that a melt pool 130 forms on a material surface.In addition, the laser beam 110 heats the powdered filler material 120, which comprises hard material particles and a matrix material. For this purpose, the laser beam 110 can have a reduced core intensity. As the molten pool 130 cools, a welded functional layer 140, for example, a wear-resistant layer, forms from the hard material particles and the matrix material. The welded functional layer 140 makes the material surface more resistant and increases its load-bearing capacity.

[0063] Figure 2 shows the jet nozzle 1 in a side view, with the feed direction 2 pointing out of the plane of the drawing. The jet nozzle 1 can be coupled to other components of a laser system, such as laser optics or a process adapter, via a flange section 9. A proximal region 10 adjoins the flange section 9. A coolant inlet 13 and a coolant outlet 14, which are part of a cooling system of the jet nozzle 1 and which protrude radially from the jet nozzle 1, can be provided at least partially in the proximal region 10. A distal region 8 is formed at the end of the jet nozzle 1 opposite the proximal region 10. The distal region is a component of the funnel-shaped nozzle mouth 6. This has, in a circumferential direction around the light channel 3, a powder section 11 in which the powder unit 7 is arranged.A powder unit-free feed section 12 adjoins the powder section 11 in the circumferential direction. The feed section 12 can be designed as a process gas section 61 (see, for example, Figure 9), which is part of a process gas unit 60.

[0064] Figure 3 shows the jet nozzle from Figure 2 in a perspective view. The light channel 3 is a hollow channel with the outer surface 4, within which the at least one laser beam 110 runs. The outer structure 5 surrounds the light channel 3 from the flange section 9 to the distal region 10. The nozzle mouth 6 is a substantially funnel-shaped region of the jet nozzle 1. The funnel shape of the nozzle mouth 6 serves, among other things, to enable the nozzle mouth 6 to form the plurality of injector guides 19 in the region of the powder unit 7. A powder injector 16 (see Figure 4) is inserted into each of these injector guides 19, which directs the powdered filler material 120 onto the at least one laser beam 110 and / or the workpiece 100 in a process-appropriate manner. The powder unit 7 extends along the powder section 11, to which the powder unit-free feed section 12 adjoins in the circumferential direction.The feed section 12 is the area of ​​the nozzle mouth 6 in which no injector guides 19 are provided, so that no powdered filler material 120 is supplied via it. In one embodiment, the feed section 12 can be shaped as a process gas section 61, so that a process gas is supplied via it. The jet nozzle 1 can be manufactured using additive manufacturing processes, in particular using powder bed melting. For this purpose, the jet nozzle 1 can be made of 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. In powder bed melting, the material to be processed is in powder form. A laser beam heats the powder along the intended geometry, whereby the powder liquefies and bonds firmly.Powder bed melting can be performed, for example, as Selective Laser Melting (“SLM”) or Selective Laser Sintering (“SLS”).

[0065] Figure 4 shows the blasting nozzle 1 with additional components attached. A coupling ring 15 is connected to the flange section 9, which secures the blasting nozzle 1 to the connected unit, for example, the laser optics or the process adapter. Powder injectors 16 are inserted into the injector guides 19 of the powder unit 7. The powder injectors 16 convey the powdered filler material 120 and apply it to the workpiece 100 with the intended focus. The individual powder injectors 16 can apply different powder foci. Alternatively, the powder injectors 16 can be directed at the same focal point. The powder injectors 16 are arranged in the injector guides 19 provided for this purpose in the powder unit 7 in the powder section 11. The feed section 12 is free of powder injectors 16. Furthermore, an inlet nozzle 17 is inserted into the coolant inlet 13 and an outlet nozzle 18 is inserted into the coolant outlet 14.These connect the coolant inlet 13 and the coolant outlet 14 to a coolant circuit.

[0066] Figure 5 shows the jet nozzle 1 in a plan view of the distal region 8. The cross-sectional area of ​​the light channel 3, which runs orthogonally to the longitudinal direction of the jet nozzle 1, deviates from a circular shape and is elongated in the feed direction 2. In the distal region 8, the cross-sectional area of ​​the light channel 3 is designed like an elongated hole, with a partial circular section adjoining two opposite ends of a rectangular section. Two laser beams are guided within the light channel 3: a primary beam 111 and a secondary beam 112. The primary beam 111 and the secondary beam 112 can originate from the same fiber optic cable. A provided laser light can be split into a parallel beam bundle by a collimating lens. The beam bundle can, for example, form the primary beam 111 and the secondary beam 112 from a single laser beam using a wedge plate.The respective centers of the primary beam 111 and the secondary beam 112 are offset in a line in the feed direction 2 to a center 20 of the light channel 3.

[0067] In the present case, the secondary beam 112 is located in front of the primary beam 111 in the feed direction 2 and does not interact with a powder caustic. The secondary beam 112 can thus be used to preheat the workpiece 100 before the primary beam 111 and the powdered filler material 120 heated by the primary beam 111 strike the workpiece 100. The secondary beam 112 thus creates a first process zone that serves to preheat the workpiece 100, and the primary beam 111 creates a second process zone that serves to weld the powdered filler material 120 onto the workpiece 100. These different process zones enable defect-free welding in which no deficiencies, in particular no fusion defects, pores, cracks, and / or dissolution of carbides in the matrix material, occur. It is also possible to guide the secondary beam 112 in the feed direction 2 after the primary beam 111.Thus, the secondary beam 112 can be used to reheat the workpiece 100 and thus contribute to a more uniform cooling, which prevents the occurrence of inclusions or other imperfections.

[0068] The primary beam 111 and the secondary beam 112 are arranged in close proximity to one another. The front partial circle section of the elongated hole in the feed direction 2 is concentric with the secondary beam 112, while the rear partial circle section of the elongated hole is concentric with the primary beam 111. A center of the cross-sectional area is eccentric to a center point of the primary beam 111 and to a center point of the secondary beam 112. A tertiary beam can also be provided, so that, for example, the secondary beam is arranged in front of the primary beam in the feed direction and the tertiary beam is arranged after the primary beam in the feed direction. The individual laser beams are guided unshielded from one another, so that there is exactly one light channel 3 with exactly one lateral surface 4, which results in minimal thermal losses.

[0069] Because the primary jet 111 in Figure 5 is arranged behind the secondary jet 112 without any radial offset in the feed direction 2 and the secondary jet 112 serves to preheat the workpiece, it is desirable that the powdered filler material does not interact with the secondary jet 112. This ensures that, on the one hand, the secondary jet 112 can exclusively perform the function of preheating the workpiece and, on the other hand, the powdered filler material is only heated by the primary jet 111 and not by the secondary jet 112. This is achieved by the jet nozzle 1 shaping the powder unit 7 in the region of the nozzle mouth 6 in such a way that it forms the powder section 11 around the light channel 3 in the circumferential direction, to which the powder unit-free feed section 12 is connected in the circumferential direction.In addition to the powder unit 7, the process gas unit 60 can also be formed, which forms the process gas section 61, in which case the feed section 12 is formed as a process gas section 61. The feed section 12 is formed in a region of the nozzle mouth 6 facing the feed direction 2. The powder section 11 extends along the elongated hole that forms the cross-sectional area of ​​the light channel 3 in the distal region 8. Analogous to a circular arc, the powder section 11 extends along an elongated hole arc, in particular horseshoe-shaped, around the light channel 3. The powder section 11 therefore extends in the circumferential direction around the light channel 3 by a wrap angle of less than 360°, in particular between 90° and 330°, further in particular between 180° and 300°, relative to a center point of the light channel.This ensures that the powdered filler material flowing out of the injectors 16, which are inserted into the injector guides 19, interacts only with the primary jet 111. The secondary jet 112 can thus form a process zone independent of the primary jet 111. The powder section 11 and the feed section 12 form a slotted hole in plan view. This further contributes to reducing or avoiding the deficiencies identified above.

[0070] Figure 6 shows the jet nozzle 1 in a plan view of the flange section 9. The cross-sectional area of ​​the light channel 3, which runs orthogonally to the longitudinal direction of the jet nozzle 1, also deviates from a circular shape in the region of the flange section 9 and is elongated in the feed direction 2. The extension of the cross-sectional area can decrease from the distal region 8 to the flange section 9. In the region of the nozzle mouth 6, the cross-sectional area can be elongated such that it is at least 1.5 times, in particular at least twice, as large in the feed direction as it is transverse to the feed direction. The flange section 9 has such a radial extension that the injector guides 19 are not visible from the plan view of the proximal region 10.

[0071] Figure 7 shows the jet nozzle 1 in a further perspective view. The nozzle mouth 6 has a curved funnel shape. The injector guides 19, into which the powder injectors 16 can be inserted, are formed within the individual curvatures. In the feed direction 2, the light channel is elongated in a manner deviating from a circular shape in order to achieve the advantages disclosed. In the circumferential direction around the light channel 3, the nozzle mouth 6 has the powder unit 7. This extends in the circumferential direction around the light channel 3 along the powder section 11, which is adjoined by the powder-free feed section 12.

[0072] Figure 8 shows a perspective sectional view of the jet nozzle 1. The light channel 3 has a conical shape, so that the cross-sectional area of ​​the light channel 3, which runs orthogonally to the longitudinal direction of the jet nozzle 1, is smaller in the distal region 8 than in the proximal region 10. The coolant inlet 13 and the coolant outlet 14 are arranged in the proximal region 10 of the jet nozzle 1 and protrude in the radial direction from the jet nozzle 1. Figure 8 shows an injector guide 19 in section. This is arranged in the powder section 11. In the feed section 12, no injector guide 19 is provided for guiding the powder jet. The jet nozzle 1 has a cooling system 30. A cooling medium, for example water, is fed back to a radially inner cooling chamber 31 via the coolant inlet 13 in the proximal region 10. The cooling medium can be distributed in the proximal region 10 in the circumferential direction around the light channel 3.The cooling medium runs from the proximal region 10 to the nozzle orifice 6. The radially inner cooling chamber 31 is formed at least in the nozzle orifice 6. It can run from the distal region 8 to the proximal region 10 and be designed in the manner of an annular gap segment that extends circumferentially around the light channel 3. In the region of the nozzle orifice 6, the radially inner cooling chamber 31 extends circumferentially around the light channel 3. The radially inner cooling chamber 31 has a constant width in the radial direction in the region of the nozzle orifice 6 and is concentric with the light channel 3 in a cross-sectional area extending orthogonally to a longitudinal direction of the jet nozzle 1.

[0073] In the distal region 8, a transition 32 is provided between the radially inner cooling chamber 31 and a radially outer cooling chamber 33. The radially outer cooling chamber 33 has a radial width that decreases in the radial direction in the region of the nozzle mouth 6 towards the distal region 8. 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 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is arranged in the feed section 12. The feed section 12 does not have any injector guides 19 for guiding the powder jet, whereby sufficient installation space is available for the transition 32.

[0074] The radially outer cooling chamber 33 has a cooling structure to increase the surface area. The cooling structure can be manufactured using an additive manufacturing process. It ensures that the cooling medium comes into contact with as much surface area as possible during the return from the distal region 8 to the proximal region 10, thus promoting heat dissipation. The cooling structure is optimized to minimize pressure losses of the cooling medium. This can be achieved using a honeycomb structure 34, as shown in Figure 8.

[0075] Figure 9 shows the jet nozzle 1 of a further embodiment in a plan view of the distal region 8. The cross-sectional area of ​​the light channel 3, which runs orthogonally to the longitudinal direction of the jet nozzle 1, deviates from a circular shape and is elongated in the feed direction 2. In the distal region 8, the cross-sectional area of ​​the light channel 3 is designed like an elongated hole, in which a partial circular section adjoins two opposite ends of a rectangular section. The primary beam 111 and the secondary beam 112 are guided within the light channel 3. The respective centers of the primary beam 111 and the secondary beam 112 are offset in a line from the center 20 of the light channel 3 in the feed direction 2.

[0076] The primary beam 111 has a beam center that coincides with a first powder focus 21. The first powder focus 21 is the point on which the injectors of a first powder section 22 are focused. The first powder section 22 forms a first powder caustic. Accordingly, the secondary beam 112 has a beam center that coincides with a second powder focus 23. The second powder focus 23 is the point on which the injectors of a second powder section 24 are focused. The second powder section 24 forms a second powder caustic. The primary beam 111 and the secondary beam 112 are offset from one another in the feed direction 2. Accordingly, the first powder focus 21 is also offset from the second powder focus 23. The powder unit 7, which has the first powder section 22 and the second powder section 24, can thus form two different powder foci.In addition, a powder mass flow delivered from the injectors of the first powder section 22 can differ from a powder mass flow delivered from the injectors of the second powder section 24. A gap can be provided between the first powder section 22 and the second powder section 24, so that the powder mass flow delivered by the first powder section 22 interacts exclusively with the primary jet 111 and the powder mass flow delivered by the second powder section 24 interacts exclusively with the secondary jet 112.

[0077] The first powder section 22 and the second powder section 24 contribute to an increase in the deposition rate by creating at least two process zones within the jet nozzle 1. This can increase the track width of the applied functional layer. Furthermore, improved shielding gas coverage with lower shielding gas consumption is achieved, since the shielding gas supply can be more localized.

[0078] The primary beam 111 and the secondary beam 112 are arranged in close proximity to each other. The front pitch circle section of the elongated hole in the feed direction 2 is concentric with the secondary beam 112, while the rear pitch circle section of the elongated hole is concentric with the primary beam 111. The center point 20 of the cross-sectional area is eccentric to the center point of the primary beam 111 and the center point of the secondary beam 112.

[0079] Figure 10 shows the jet nozzle 1 in a plan view of the distal region 8. The primary beam 111 and the secondary beam 112 are guided within the light channel 3. The secondary beam 112 is in front of the primary beam 111 in the feed direction 2 and does not interact with a powder caustic, as described in more detail in connection with Figure 5. During the interaction of the laser beams with the material surface and the powder jet, a vapor flare can form between the jet nozzle 1 and the workpiece 100. If this vapor flare is not contained, it can interact in an undesirable manner with the at least one laser beam and / or the unprocessed and / or processed material surface. In the region adjoining the powder section 11, the feed section 12 can therefore be designed as a process gas section 61.This is formed by the process gas unit 60, which is arranged radially outside the light channel 3 and directs the process gas onto the workpiece. The process gas section 61 can prevent undesired propagation of the vapor flare and thus contribute to precise workpiece machining with a robust jet nozzle design. The process gas section 61 can form at least one, in this case three, outlet openings 62. The outlet openings 62 are formed on an end face of the jet nozzle 1. An additional injector for supplying the process gas without additional material can be inserted into the respective outlet opening 62. An inner diameter of the outlet opening 62 can be smaller than an inner diameter of the injector guides 19. The process gas section 61 also prevents powder particles from adhering to the end face of the jet nozzle 1. In this respect, the process gas section 61 also increases the service life of the jet nozzle 1.The process gas section 61 and the powder section 11 can be provided circumferentially around the elongated hole formed by the light channel 3. Thus, the primary beam 111 and the secondary beam 112 are completely within the beams composed of the powder beam and the process gas beam. The jet nozzle 1 has a plurality of injector guides 19. The injector guide, which is arranged at the end facing away from the feed direction 2, represents a rear injector guide 72. Figure 11 shows a longitudinal section of the jet nozzle 1 with a workpiece 100. The laser beam 110 extends along a longitudinal axis 43 of the light channel 3. The longitudinal axis 43 of the light channel 3 is inclined by a posterior angle of attack 44 relative to a perpendicular to the workpiece surface 41. The posterior angle of attack 44 describes the inclination of the jet nozzle 1 opposite to the feed direction 2.This posterior inclination directs, for example, reflected laser radiation onto an absorption section. In addition to the posterior inclination, the jet nozzle 1 can also be inclined laterally relative to the workpiece 100, as further described in connection with Figure 17. The posterior angle of attack can be between 2° and 45°, in particular between 10° and 30°, further in particular between 15° and 25°. To achieve the inclination or angle of attack 44°, it is possible to incline the jet nozzle 1 relative to the workpiece 100 or to incline the workpiece 100 relative to the jet nozzle 1. The surface roughness of the absorption surfaces of the absorption section is between 5 pm and 100 pm, in particular between 50 pm and 50 pm. The absorption section can also be provided with an absorbent coating that promotes absorption.An end face 42 of the jet nozzle 1 can be angled relative to the longitudinal axis 43 of the light channel 3, so that the end face 42 runs plane-parallel to the workpiece 100. Thus, the distance from the nozzle orifice 6 to the workpiece 100 is increased. This reduces the thermal load on the nozzle orifice 6. Furthermore, the angled end face 42 enables improved shielding of the workpiece 100. This is because the plane-parallel surface of the end face 42 enables a shielding gas flow exiting orthogonally to the workpiece 100.

[0080] Figure 12 shows a further embodiment of the jet nozzle 1. The nozzle mouth 6 has a bevel 50, by which a part of the nozzle mouth 6 is cut off. The bevel 50 has the effect that the powder section 11 and the powder-section-free feed section 12 are cut off in the circumferential direction around the light channel 3. The bevel 50 reduces the volume of the nozzle mouth 6 compared to the embodiment in which no bevel 50 is present. This ensures that the nozzle mouth 6 takes up less installation space. The jet nozzle 1 with the bevel 50 can be used, for example, to coat a brake disc. The brake disc can have a receptacle that protrudes axially from the functional surface to be coated. The bevel 50 ensures that the jet nozzle 1 can be flexibly moved on the functional surface to be coated and can be moved close to the receptacle.The bevel 50 can be substantially flat and extend in a plane that is inclined relative to the longitudinal direction of the jet nozzle. The bevel 50 represents a boundary surface of the nozzle orifice 6, in which no powder unit 7 is provided. In the distal region 8, the bevel 50 is arranged so close to the light channel 3 that no injector guides 19 are provided on an end face of the jet nozzle 1 facing the workpiece in the region of the bevel 50.

[0081] Figure 13 shows a perspective view of another jet nozzle 1 with the bevel 50. The bevel 50 can run in the distal region 8 in the manner of a passante 51 at an opening of the light channel 3. The passante 51 defines the orientation of the bevel 50 at the nozzle mouth 6. The passante 51 runs in the end face of the jet nozzle 1 facing the workpiece along a straight line or an arc that neither intersects nor touches the opening. In addition, a further bevel 50 can be present on the end face of the jet nozzle 1 facing away from the workpiece. The two bevels 50 can be arranged symmetrically to one another. The distance of the passante 51 from the center point 20 of the light channel 3 is greater than the distance of the corresponding section of the elongated hole from the center point 20 of the light channel 3.The distance between the passante 51 and an outer edge of the elongated hole is selected such that the wall thickness therebetween ensures sufficient strength and resilience of the jet nozzle 1.

[0082] The orientation of the passante 51 and thus the orientation of the bevel 50 on the nozzle mouth 6 can be varied for different jet nozzles 1 depending on the respective field of application. For example, the passante 51 can run in the feed direction 2. Alternatively, the passante 51 can run, for example, transversely to the feed direction 2. Further alternatively, the passante 51 can run, for example, at an angle to the feed direction 2 that lies between a course along the feed direction 2 and transversely to the feed direction 2. In this case, the passante 51 runs along the transition section between the long side of the elongated hole and the pitch circle section of the elongated hole. The course of the passante 51 determines the orientation of the bevel 50.

[0083] The powder unit 7 at the nozzle mouth 6 forms the powder section 11 in a circumferential direction around the light channel 3. This section has a plurality of injector guides 19, into each of which a powder injector 16 can be inserted. A first injector guide 70 is located substantially opposite a second injector guide 71 relative to the first powder focus 21. In particular, the first injector guide 70 at the first powder focus 21 is a point-mirror image of the second injector guide 71. In the exemplary embodiment, there are four further injector guides, two of which are opposite one another. In total, the jet nozzle in the present case therefore has six injector guides, of which the injector guides in a first powder section 73 each have an opposite counterpart in a second powder section 74. The opening of the light channel 3 can be an elongated opening in the manner of an elongated hole or, as shown, a circular opening.Figure 14 shows the jet nozzle 1 from Figure 13, with powder injectors 16 inserted into the respective injector guides 19. The powder injectors extend obliquely to the plane in which the end face of the jet nozzle 1 extends. Furthermore, each powder injector 16 has an opposite powder injector 16, mirrored at the first powder focus 21. The first powder section 73 is separated from the second powder section 74 on both sides along the circumferential direction by a powder section gap.

[0084] Figures 15 and 16 show a further embodiment of the jet nozzle 1. A first injector guide 70 is located opposite the second injector guide 71 with respect to the first powder focus 21. In this case, the jet nozzle has a total of four injector guides 19. In Figure 16, powder injectors 16 are inserted into the respective injector guides 19. The embodiment shown in Figures 15 and 16 is particularly suitable for producing precise functional layers with stepped component symmetries.

[0085] Figure 17 shows the blasting nozzle 1 aligned with a workpiece 100 having a hub cap 101. The drawing plane in Figure 17 is the plane to which the feed direction 2 runs orthogonally. The blasting nozzle 1 is inclined about a feed axis along which the feed direction 2 runs. In Figure 17, the blasting nozzle 1 is moved toward a right flank of the hub cap 101, so that the blasting nozzle 1 is inclined to the right about the feed axis. Due to the inclination of the blasting nozzle 1 about the feed axis, a lateral angle of attack 45 is formed between the perpendicular 41 of the workpiece surface and the longitudinal axis 43 of the light channel. The lateral angle of attack 45 is independent of the posterior angle of attack 44, as described, for example, in connection with Figure 11.The lateral angle of attack 45 enables, particularly in conjunction with the bevel 50, the jet nozzle 1 to move closer to the hub cap 101, whereby the functional layer can be applied to the workpiece 100 right up to the hub cap 101. If the workpiece 100 is a brake disc, this enables the entire friction surface of the brake disc up to the base of the hub cap 101 to be provided with the functional layer. The lateral angle of attack 45 can be between 2° and 45°, in particular between 10° and 30°, further in particular between 15° and 25°. One of the plurality of injector guides 19, in particular each of the plurality of injector guides 19, is inclined relative to the longitudinal axis 43 of the light channel in the plane shown, to which the feed direction 2 runs orthogonally.In particular, the at least one injector guide 19, in particular the first injector guide 70 and / or the second injector guide 71, can be inclined by an injector angle 46 between 10° and 25°. The lateral angle of incidence 45 indicates that there is at least one injector guide 75 inclined toward the workpiece 100. The injector guide 75 inclined toward the workpiece 100 can be any of the plurality of injector guides 19. A workpiece angle 47, which extends between the direction of the injector guide 75 inclined toward the workpiece 100 and the workpiece surface, is determined by the sum of the lateral angle of incidence 45 and the injector angle 46. It has been found that excessively acute workpiece angles 47 cause waviness in the applied functional layer.In this respect, the lateral angle of attack 45 and the injector angle 46 are coordinated such that the workpiece angle 47 is a maximum of 30°, in particular a maximum of 45°, and more particularly a maximum of 50°. At this workpiece angle 47, an optimal ratio of the quality of the functional layer and the proximity of the functional layer to the hub cup 101 is achieved. Thus, with these angles of attack 45 and / or these injector angles 46, a smooth functional layer that is free of waviness can be efficiently realized. Thus, with the opposing arrangement of the injector guides 19, these angles of attack 45 and / or these injector angles 46 further contribute to avoiding deficiencies in the functional layer. Furthermore, the bevel 50 contributes to the jet nozzle 1 moving flush against the hub cup 101.

[0086] Where applicable, all individual features presented in the embodiments may be combined and / or exchanged without departing from the scope of the invention.

[0087] List of reference symbols

[0088] 1 jet nozzle 31 radial inner cooling chamber

[0089] 2 Feed direction 32 Transition

[0090] 3 Light channel 33 Radial outer cooling chamber 4 Shell surface 30 34 Honeycomb structure

[0091] 5 External structure 41 Solder of the workpiece surface

[0092] 6 Nozzle mouth 42 front side

[0093] 7 Powder unit 43 Longitudinal axis of the light channel

[0094] 8 distal area 44 posterior angle of attack 9 flange section 35 45 lateral angle of attack

[0095] 10 proximal area 46 injector angle

[0096] 11 Powder section 47 Workpiece angle

[0097] 12 Feed section 50 bevel

[0098] 13 Coolant inlet 51 Passante 14 Coolant outlet 40 60 Process gas unit

[0099] 15 Coupling ring 61 Process gas section

[0100] 16 Powder injector 62 Outlet opening

[0101] 17 Inlet nozzle 70 first injector guide

[0102] 18 Drain connection 71 Second injector guide 19 Injector guide 45 72 Rear injector guide

[0103] 20 Center of the light channel 73 first powder section

[0104] 21 first powder focus 74 second powder section

[0105] 22 first powder section 75 injector guide inclined towards the workpiece

[0106] 23 second powder focus

[0107] 50 24 second powder section

[0108] 100 workpieces

[0109] 30 Cooling system 110 Laser beam 120 Powdered filler material

[0110] 111 Primary beam 5 130 Melt pool

[0111] 112 Secondary beam 140 Functional layer

Claims

Claims 1. A jet nozzle (1) for laser material deposition along a feed direction (2), comprising a light channel (3) for guiding at least one laser beam directed onto a workpiece; and a powder unit (7) arranged radially outside the light channel (3) for guiding at least one powder jet to be applied to the workpiece with at least a first powder focus (21); wherein the powder unit (7) forms a powder section (11) at a nozzle mouth (6) in a circumferential direction around the light channel (3), which powder section has a plurality of injector guides (19), into each of which, in particular, a powder injector (16) can be inserted, wherein a first injector guide (70) is located substantially opposite a second injector guide (71) with respect to the first powder focus (21).

2. Jet nozzle (1) according to claim 1, wherein the substantially opposite injector guides (70, 71) are point-mirrored at the first powder focus (21), so that two of the plurality of injector guides (19) are opposite each other with respect to the center point (20) of the light channel (3).

3. Jet nozzle (1) according to one of the preceding claims, wherein the plurality of injector guides (19) is an odd number, wherein a rear injector guide (72) which is located rearward in the feed direction (2) is the only one of the plurality of injector guides (19) which does not have an opposite injector guide, or wherein the plurality of injector guides (19) is an even number, so that each injector guide (19) has an opposite injector guide.

4. Jet nozzle (1) according to one of the preceding claims, wherein in a plane to which the feed direction (2) is orthogonal, the first injector guide (70) and / or the second injector guide (71) is inclined relative to a longitudinal axis (43) of the light channel (3), preferably by an injector angle (46) of between 10° and 25°.

5. Jet nozzle (1) according to one of the preceding claims, wherein each of the plurality of injector guides (19) is aligned with the first powder focus (21), wherein in particular the first powder focus (21) lies on a longitudinal axis (43) of the light channel (3) along which the laser beam runs.

6. Jet nozzle (1) according to one of claims 1 to 4, wherein the plurality of injector guides (19) are directed to a first part towards the first powder focus (21) and is aligned to a second part with a second powder focus (23), wherein in particular the first powder focus (21) and the second powder focus (23) run along the feed direction (2) and form a focus line.

7. Jet nozzle (1) according to one of the preceding claims, wherein a first powder injector is inserted into the first injector guide (70) and is prepared to convey a first powder mass flow and a second powder injector is inserted into the second injector guide (71) and is prepared to convey a second powder mass flow, wherein the first powder mass flow differs from the second powder mass flow and wherein in particular the first powder mass flow conveys a powder which differs from the second powder mass flow.

8. Jet nozzle (1) according to one of the preceding claims, wherein a cross-sectional area of ​​the light channel (3) extending orthogonally to the longitudinal direction of the jet nozzle (1) is elongated in the feed direction (2) deviating from a circular shape and the powder section (11) extends along an elongated hole arc, in particular horseshoe-shaped, around the light channel (3).

9. Jet nozzle (1) according to one of the preceding claims, wherein the powder section (11) is composed of a first powder section (73) and a second powder section (74) and the first powder section (73) is separated from the second powder section (74) by a powder section gap.

10. Jet nozzle (1) according to one of the preceding claims, wherein the powder section (11) extends in the circumferential direction around the light channel (3) by a wrap angle (23) between 45° and 330°, in particular between 90° and 300°, further in particular between 180° and 300°, relative to a center point (20) of the light channel (3).

11. Jet nozzle (1) according to one of the preceding claims, wherein the light channel (3) is adapted to guide a plurality of laser beams, the plurality having a first laser beam as the primary beam (111) and a second laser beam as the secondary beam (112).

12. Jet nozzle (1) according to one of the preceding claims, wherein in the circumferential direction, a powder unit-free feed section (12) adjoins the powder section (11) and is formed in a region of the nozzle mouth (6) facing towards or away from the feed direction (2), wherein a process gas unit (60) for guiding a process gas is arranged in particular radially outside the light channel (3), wherein the process gas unit (60) forms a process gas section (61) in the circumferential direction, which takes up the feed section (12).

13. Jet nozzle (1) according to one of the preceding claims, which is produced by means of an additive manufacturing process and consists in particular of copper or a copper alloy, further in particular a copper-chromium-zirconium alloy.

14. Jet nozzle (1) according to one of the preceding claims, wherein the nozzle mouth (6) has a bevel (50) through which a part of the nozzle mouth (6) is cut off, wherein the bevel (50) is substantially flat and extends in a plane which is inclined with respect to the longitudinal direction of the jet nozzle (1).

15. System with a jet nozzle (1) according to one of the preceding claims and a workpiece (100), wherein the jet nozzle (1) is inclined about a feed axis, along which the feed direction (2) runs, in order to form a lateral angle of attack (45) with respect to the workpiece (100), so that in a plane to which the feed direction (2) runs orthogonally, a longitudinal axis (43) of the light channel (3), along which the laser beam runs, deviates from a normal (41) of a workpiece surface of the workpiece (100).

16. System according to claim 15, wherein the lateral angle of attack (45) is between 2° and 45°, in particular between 5° and 30°, further in particular between 10° and 25°.

17. System according to claim 16, wherein at least one, in particular each, of the plurality of injector guides (19) is inclined in a plane to which the feed direction (2) is orthogonal, relative to the longitudinal axis (43) of the light channel (3), preferably inclined by an injector angle (46) between 10° and 25°, wherein an angle sum of the lateral angle of incidence (45) and the injector angle (46) is such that an injector guide inclined towards the workpiece (100) (75) encloses with the workpiece (100) a workpiece angle (47) of a maximum of 30°, in particular a maximum of 45°, further in particular a maximum of 50°.

18. A method for laser deposition welding along a feed direction (2), in particular by means of a jet nozzle (1) or a system according to one of the preceding claims, comprising the following steps: Aligning the jet nozzle onto a workpiece (100); Tilting the jet nozzle (1) about a feed axis along which the feed direction (2) runs, so that the jet nozzle (1) forms a lateral angle of attack (45) of less than 90° with respect to the workpiece (100) in a plane to which the feed direction (2) runs orthogonally.

19. The method according to claim 18, wherein the jet nozzle (1) is inclined such that an injector guide (75) inclined towards the workpiece (100) encloses a workpiece angle (47) of a maximum of 30°, in particular a maximum of 45°, further in particular a maximum of 50°, with the workpiece (100).

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