Beam nozzle with opposed injector guides

Abstract

The invention relates to a beam nozzle (1) for laser cladding welding in 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 beam to be applied to the workpiece at least with a first powder focus (21); wherein the powder unit (7) forms a powder section (11) at a nozzle opening (6) in the circumferential direction around the light channel (3), which powder section has a plurality of injector guides (19), in particular in each case a powder injector (16) can be inserted, and wherein, with respect to the first powder focal point (21), the powder section (11) forms a powder section (11) in the circumferential direction around the light channel (3), said powder section (11) having a plurality of injector guides (19), in particular in each case a powder injector (16) can be inserted. The first injector guide (70) is substantially opposite the second injector guide (71).

Description

Technical Field

[0001] The invention relates to a beam nozzle for laser cladding welding in a feed direction and a method for laser cladding welding. Background Art

[0002] Laser cladding welding is used, for example, in the fields of repair, coating, and / or joining technology. A distinction can be made between conventional laser cladding welding techniques (laser metal deposition (LMD), direct metal deposition (DMD), or direct energy deposition (DED)) and so-called high-speed laser cladding welding (high-speed laser metal deposition (HS-LMD) or ultra-high-speed laser application (EHLA)). The HS-LMD method is described, for example, in publications DE 10 2011 100 456 A and DE 10 2018130 798 A1. Another method for laser cladding welding is known from Chinese patent application CN 109175372 A.

[0003] Laser cladding welding can be used to apply a functional layer to a workpiece. This generally results in an increase in the load-bearing capacity of a workpiece processed by laser cladding welding compared to an unprocessed workpiece. The functional layer can, for example, serve as a wear protection layer. Application of the functional layer is based on melting of the workpiece surface, application of a powdered additive material, and subsequent cooling, resulting in a material-to-material connection between the base structure with hard material particles and the workpiece surface. Laser cladding welding thus embeds itself into the internal material structure of the workpiece and alters it. In some cases, this can lead to defects in the internal material structure. These defects can be detrimental to the desired increase in load-bearing capacity. Defects can be microscopic in nature and therefore can only be detected with great effort. Summary of the Invention

[0004] Starting from the known prior art, the object of the present invention is to provide an improved jet nozzle and an improved method for laser cladding welding in the feed direction. The present invention is particularly intended to improve the weld quality of the applied functional layer and the entire workpiece, and to reduce or avoid defects in the weld connection between the powdered additional material and the material surface. The jet nozzle can be designed to enable reliable application of the functional layer in the hub cup region of rotationally symmetrical components such as brake discs, in particular at a lateral angle of attack (lateral angle of attack) greater than 5° between the jet nozzle and the component. The lateral angle of attack describes the inclination of the jet nozzle relative to the workpiece about the feed axis, along which the feed direction extends. Defects to be avoided can include a corrugated applied functional layer, which deviates from the desired smooth functional layer and can be caused, in particular, by improperly directing the additional material onto the component surface. Defects can also be pores, i.e., air pockets, within the applied functional layer or between it and the material surface. Pores can occur more frequently, particularly when the material surface is a cast material. Defects can also be cracks in the applied functional layer that extend perpendicular to the material surface. Defects can also be caused by the dissolution of powder particles, in particular carbides, of the powdered additional material in the matrix of the powdered additional material, which leads to embrittlement of the matrix. The present invention is also particularly directed to providing a thermally resistant and reliable jet nozzle. The present invention can also be directed to designing a jet nozzle such that it ensures reliable and precise laser cladding welding at extremely high cycle times.

[0005] This object is achieved by a jet nozzle having the features of claim 1. Advantageous developments result from the dependent claims, the description and the drawings.

[0006] Accordingly, a beam nozzle for laser cladding welding along a feed direction is proposed. The beam nozzle has an optical channel for guiding at least one laser beam directed onto a workpiece. Laser cladding welding can be a method used for high-speed laser metal deposition (HS-LMD). The feed direction is the direction of motion of the beam nozzle relative to the workpiece. This feed direction can be caused by: motion of the workpiece, in particular rotational motion; motion of the beam nozzle; or a combination of both motions. The feed direction and the associated feed motion can be constant during the process flow. Alternatively, they can vary with the respective process phase. The workpiece can be rotationally symmetrical, such as a brake disk, hydraulic cylinder, pressure roller, or plain bearing. The laser beam can be irradiated through the optical channel. The laser beam can be provided by a laser source, which is guided from the laser source via a fiber optic cable to a laser system. The laser system splits the laser beam via a collimating lens and focuses the laser beam to the process requirements via laser optics before it enters the beam nozzle. The light channel can be a hollow channel extending through the entire jet nozzle in the longitudinal direction. In addition to the laser beam, process gas can also be guided to the workpiece surface through the light channel.

[0007] The jet nozzle further comprises a powder unit arranged radially outside the light channel and configured to direct at least one powder jet, which is applied to the workpiece at least at a first powder focus. The powder unit can be radially outside the light channel, relative to the longitudinal direction of the jet nozzle, and can be part of an outer structure that encloses the light channel in a closed manner. The powder jet can carry a powdered additive material comprising hard material particles, particularly carbides, and a matrix material. The powder unit can be a portion of the jet nozzle configured to directly or indirectly direct the powdered additive material. The powder jet is fully or partially focused onto the first powder focus. The first powder focus is the location at which the powder unit directs the powder jet. The first powder focus can be non-concentric with the center of the light channel.

[0008] At the nozzle mouth, the powder unit forms a powder section in the circumferential direction around the beam channel. This powder section has multiple injector guides, into each of which a powder injector can be inserted, wherein the first injector guide and the second injector guide are essentially opposite each other, relative to the first powder focus. The injector guide can serve as a receptacle for the powder injector. Alternatively, the injector guide itself forms the injector opening, through which the powder material is conducted through the jet nozzle without relying on an additional powder injector. The powder unit can be part of the nozzle mouth. The nozzle mouth is the part of the jet nozzle facing the workpiece. The end section of the nozzle mouth has a distal region. This is the part of the nozzle mouth closest to the workpiece. In the section facing away from the workpiece, the jet nozzle has a proximal region and a flange section. The proximal region and the flange section are the parts of the jet nozzle facing away from the workpiece. The nozzle can be connected to another component of the laser system, such as the laser optics or a process unit, via the flange section. The powder section can form a section of the nozzle mouth's circumference around the light channel. For example, the powder section can comprise a substantial portion of the nozzle mouth's circumference. The injector guide can be a cylindrical or conical through-opening in the nozzle mouth, into which a powder injector can be inserted. The injector guide can be introduced into the nozzle mouth by machining. However, it is preferably provided during the additive manufacturing of the jet nozzle. The injector guide can be adapted to the respective powder injector to be inserted. The first injector guide can be mirrored relative to the second injector guide at the first powder focus. It can also be mirrored with an offset of 5° to 15° around the light channel in the circumferential direction. The jet nozzle can have a lateral angle of attack. This describes the inclination of the jet nozzle relative to the workpiece about the feed axis, along which the feed direction extends. Therefore, the lateral angle of attack extends laterally relative to the feed direction. The jet nozzle can also have a rearward angle of attack. This refers to the inclination of the jet nozzle against the feed direction. Thus, the rearward angle of attack extends in the feed direction or counter to the feed direction. The jet nozzle can have at least two ejector guides lying opposite one another. In particular, it can have four or more ejector guides.

[0009] The beam nozzle thus offers greater variability in: (i) laser beam guidance; (ii) the use of powdered additive material; (iii) thermal management; and (iv) protection of the laser system, including the beam nozzle. The beam nozzle enables the establishment of multiple independent process zones with high precision. The process zone can be divided into a zone for laser cladding welding and a zone for pre-processing and / or post-processing. In the zone for laser cladding welding, at least one laser beam interacts with the powdered additive material. Pre-processing and / or post-processing can involve cleaning the material surface, pre-heating the material surface before applying the powdered additive material, post-heating the material surface after the powdered additive material has been applied, or a combination thereof. During pre-processing and / or post-processing, the laser beam can impinge on the workpiece without interacting with the powdered additive material. Independent process zones improve weld quality and, therefore, the load-bearing capacity of the applied functional layer, particularly the wear protection layer, and the entire workpiece. Additional process gas stabilizes the process zone and increases the precision of the laser cladding welding and the service life of the beam nozzle. Furthermore, the opposing injector guides can help ensure that the functional layer is applied smoothly (ie without any ripples) to the workpiece surface of the workpiece and that the stability of the jet nozzle is increased.

[0010] In particular, the jet nozzle can reduce the occurrence of joining defects. This is because joining defects can occur if the surface heated by the laser beam (e.g., a workpiece or a previously welded functional layer) is not heated sufficiently. This insufficient heating can be caused by keeping the laser power of the individual laser beams low to avoid overheating of the powdered additive material. Increased variability in laser beam guidance, increased variability in the application of the powdered additive material, and / or increased variability in the thermal management of the jet nozzle can reduce or even prevent the occurrence of joining defects, in particular by enabling balanced application of different streams of the powder beam.

[0011] In particular, the jet nozzle can reduce the formation of holes between the welded functional layer and the surface heated by the laser beam. This is because holes can form when laminae, in particular graphite laminae, in the workpiece are vaporized by the laser radiation. Holes can also form if the surface to be processed has impurities, such as oil, grease, cooling lubricants, or oxides, which cannot be completely removed by the welding process. Undesirable vaporization of impurities can be caused by setting the laser power of a single laser beam too high to avoid joining defects caused by insufficient heating. Increased variability in the guidance of the laser beam, increased variability in the application of the powdered additional material, and / or increased variability in the thermal management of the jet nozzle can reduce or even avoid the formation of holes, in particular by opposing injector guides that enable a balanced application of different streams of the powder beam.

[0012] In particular, the jet nozzle can reduce the occurrence of cracks in the welded functional layer. This is because cracks can occur if the temperature gradient between the intensely heated powdered additional material and the less intensely heated workpiece surface is so great that the material contraction that occurs during cooling induces stresses that lead to cracks. Cracking can be caused by setting the laser power of a single laser beam too high to avoid joint defects caused by insufficient heating. Increased variability in laser beam guidance, increased variability in the application of powdered additional material, and / or increased variability in the thermal management of the jet nozzle can reduce or even prevent the occurrence of cracks, particularly by opposing ejector guides that enable balanced application of different streams of the powder beam.

[0013] Furthermore, in particular, the jet nozzle can reduce the dissolution of hard material particles, in particular carbides, in the base material. The powdered additional material can contain hard material particles, in particular carbides, and a base material. The hard material particles should be present in the welded functional layer in an undissolved state to increase the load-bearing capacity of the functional layer. However, if the powdered additional material is exposed to excessively high radiation intensities, causing the hard material particles to melt, the hard material particles can dissolve. Due to the low ductility of the base material, the dissolved hard material particles cause the welded functional layer to become brittle, so that, for example, stresses caused by contraction when the workpiece cools or is loaded cannot be absorbed by the base material. Increased variability in the guidance of the laser beam, increased variability in the application of the powdered additional material, and / or increased variability in the thermal management of the jet nozzle can reduce or even prevent the dissolution of hard material particles, in particular by opposing injector guides that enable a balanced application of different streams of the powder jet.

[0014] Furthermore, in particular, the jet nozzle can prevent powder particles from adhering to the nozzle opening. In principle, due to the high process heat, reflected laser radiation and / or the metal vapor flame can cause additional material to adhere to or even weld to the nozzle opening, which can disrupt the gas and powder flows and subsequently have a negative impact on the process result. The metal vapor flame is the result of the partial vaporization of the material caused by laser cladding welding. This can cause scattering and / or absorption of the laser radiation and thus affect the preheating of the workpiece. This can further promote the formation of joining defects. Increased variability in the laser beam guidance, increased variability in the application of powdered additional material, and / or increased variability in the thermal management of the jet nozzle can reduce or even avoid the undesirable dissolution of hard material particles and the spread of the metal vapor flame, in particular by opposing injector guides that enable a balanced application of different flows of the powder jet.

[0015] The opposed injector guides reduce or prevent a wavy application of the functional layer, which deviates from the desired smooth functional layer. This wavy appearance can be caused by parameter tolerances. The at least approximately paired opposition of the injector guides, and the resulting at least approximately paired opposition of the powder injectors arranged therein, ensures fluid balance of the individual streams of the powder jet during application of the functional layer. Furthermore, the balancing element created by the opposed injector guides improves the kinematic stability of the jet nozzle. Furthermore, the jet nozzle contributes to a wider process window within which the functional layer can be applied in a manner consistent with process requirements by reducing the effects of wavy appearance caused by fluctuations in laser power, nozzle distance, and / or feed gas and / or nozzle gas. The powder caustics have a long extension in the beam direction, with the powder focus diameter being approximately constant. This prevents fluctuations in the coating, and in particular, wavy appearance.

[0016] In one embodiment, substantially opposing injector guides are mirrored at the first powder focus, so that two of the plurality of injector guides are opposite one another with respect to the center point of the optical path. Consequently, they have a geometrically specific position relative to one another. This further contributes to improving the kinematic stability of the jet nozzle and further increases the corresponding process window.

[0017] In one embodiment, the plurality of injector guides is an odd number, wherein the rear injector guide, which is located at the front in the feed direction, is the only one of the plurality of injector guides that does not have an opposing injector guide. The rear injector guide is arranged centrally with respect to the central axis of the jet nozzle, i.e., it intersects the central axis. In this regard, the powder jet emitted from this rear injector guide does not cause an imbalance with respect to the central axis, and opposing injector guides are not required. 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 high operational stability of the jet nozzle during processing, which further contributes to a smooth surface of the functional layer.

[0018] In one embodiment, the first and / or second injector guides are tilted relative to the longitudinal axis of the light tunnel in a plane extending orthogonally thereto in the feed direction, preferably at an injector angle between 10° and 25°. The individual injector guides can extend in different directions. Preferably, none of the directions is perpendicular to the feed direction. Therefore, the jet nozzle preferably does not have injector guides oriented perpendicular to the feed direction (i.e., tangential feed) and, consequently, does not have powder injectors oriented perpendicular to the feed direction (i.e., tangential feed). The tilt of the injector guides and the resulting injector angles allow the properties of the functional layer to be tailored to the process requirements. The longitudinal axis of the light tunnel, along which the laser beam extends, can be tilted in different directions relative to the perpendicular to the workpiece surface. Thus, the laser beam is not oriented orthogonally to the workpiece; for example, it can be tilted at a rearward angle of attack relative to the workpiece, for example to appropriately absorb reflected radiation via the absorption section. Furthermore, the tilted lateral angle of attack can help ensure that the functional layer can be applied geometrically up to the so-called hub cap of the brake disc. The boss forms an interfering contour, whereby interference may occur when the nozzle is oriented orthogonally to the brake disc surface.

[0019] In one embodiment, each of the multiple injector guides is aligned with a first powder focus, wherein the first powder focus is particularly located on the longitudinal axis of the optical channel (along which the laser beam extends). Accordingly, the powder injectors deliver their respective streams to the same location. The jet nozzle thus enables the powder beam to be applied to the workpiece surface at the same location, ensuring that a highly functional layer can be applied in a short period of time. For example, the first powder focus can be located centrally within the circular opening of the optical channel or eccentrically within an elongated opening. The injector guides or the powder injectors inserted therein can have a common focal point or focal region, for example, on the laser's secondary axis of symmetry.

[0020] In one embodiment, a first portion of the plurality of injector guides is aligned with a first powder focus, and a second portion of the plurality of injector guides is aligned with a second powder focus, wherein in particular the first and second powder focuses extend along the feed direction and thus form a focal line. The injector guides thus form two powder focuses, which facilitates uniform application of the functional layer along the feed direction. Injector guides arranged in the region of the first powder focus can be aligned with the first powder focus, and injector guides arranged in the region of the second powder focus can be aligned with the second powder focus. This ensures a locational and functional separation of the individual injector guides, thereby further improving the flow characteristics of the jet nozzle.

[0021] In one embodiment, a first powder injector is inserted into a first injector guide and is prepared to deliver a first powder mass flow, and a second powder injector is inserted into a second injector guide and is prepared to deliver a second powder mass flow, wherein the first powder mass flow is different from the second powder mass flow. The first powder injector can be positioned opposite the second powder injector. The first powder injector can be arranged so that it interacts with a primary beam of the laser beam. The second powder injector can be arranged so that it interacts with a secondary beam of the laser beam. The primary and secondary beams can be identical or can transmit different energies. Providing the first and second powder mass flows enables the jet nozzle to implement more than one process zone, further contributing to increased variability of the jet nozzle. In particular, the first powder mass flow delivers a different powder than the second powder mass flow. This allows for the application of a functional layer having a variable material to the workpiece. Alternatively, the first and second powder mass flows can direct the same powder onto the workpiece. Adapting the powder mass flows to the respective injectors further contributes to increased variability.

[0022] In one embodiment, a cross-section 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 a powder segment extends around the light channel along a strip hole arc, particularly in a horseshoe shape. Similar to a circular arc, the strip hole arc forms a line that encloses the strip hole in the petal area. The remaining portion of the strip hole not covered by the strip hole arc can be filled by the feed segment, and the powder segment extends along the strip hole arc. The powder segment can extend at least partially along the two opposing straight ends of the strip hole and the circular arc segment located therebetween, forming a horseshoe shape. This further facilitates the provision of more than one process zone. At least one laser beam, particularly at least one circular laser beam and / or oval laser beam, can be directed along the elongated cross-section of the light channel, resulting in the formation of more than one process zone. This facilitates welding behavior and reduces defects in the weld joint, particularly reducing the occurrence of joint defects, holes, cracks, and / or reducing the dissolution of carbides in the substrate, and improving the load-bearing capacity of the applied functional layer. The melting behavior, powder jet behavior, material joining, and cooling behavior can thus be variably adapted to the respective application and the current material properties and process parameters.

[0023] In one embodiment, the powder section includes 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 powder section and the second powder section can effectively implement opposing injector guides. Each injector guide in the first powder section can have a corresponding opposing injector guide in the second powder section. The sum of the angles of the first powder section and the second powder section can form a wrap angle. In embodiments where the powder portion includes a first powder portion and a second powder portion, when the wrap angle reaches a certain angular span as listed below, these angular spans are formed by the sum of the angular spans of the first powder portion and the angular spans of the second powder portion.

[0024] In one embodiment, the powder segment extends circumferentially around the light channel through a wrap angle that, relative to the center of the light channel, is between 45° and 330°, particularly between 90° and 300°, and even more particularly between 180° and 300°. The wrap angle can be optimized so that each injector guide has an opposing injector guide. Consequently, the powder segment can extend over a larger section around the light channel than the feed segment. This ensures a satisfactory powder supply for the powder unit, and particularly for the injectors arranged therein. Precisely adapting the powder segment and feed segment to the respective process conditions enables flawless, efficient welding. In particular, if the nozzle opening has a bevel that cuts off a portion of the nozzle opening, the wrap angle of the powder segment is between 90° and 180°. If the nozzle opening does not have a bevel, the wrap angle is preferably greater than 180°. In an embodiment where the powder segment includes a first powder segment and a second powder segment, the wrap angle represents the sum of an angle of the first powder segment and an angle of the second powder segment.

[0025] In one embodiment, the optical channel is adapted to guide a plurality of laser beams, wherein the plurality of laser beams includes a first laser beam as a primary beam and a second laser beam as a secondary beam. The primary beam and the secondary beam can originate from the same optical fiber cable. The provided laser light can be divided into parallel beam clusters via a collimating lens. For example, the beam cluster can be formed from a single laser beam into a primary beam and a secondary beam using a wedge plate. In this case, the primary beam and the secondary beam can have the same wavelength and transmit the same energy. Alternatively, the primary beam and the secondary beam can differ in their wavelength and energy. The respective center points of the primary beam and the secondary beam can be offset in a straight line with the center point of the optical channel in the feed direction. The provision of the plurality of laser beams facilitates the reliable implementation of multiple process zones.

[0026] In one embodiment, a feed section without a powder unit connects to the powder section in the circumferential direction, and the feed section without a powder unit is formed in the area 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 constitute a larger portion than the feed section. In a top view, the powder section and the feed section can extend in a closed manner along the opening of the light channel. In a top view, the area of ​​the nozzle mouth facing the feed direction is arranged at the end of the nozzle near the feed direction. The end side of the feed section points in the direction of the workpiece. The feed section can extend around the light channel in the circumferential direction within an angular span. The angular span within which the feed section extends can be smaller than the angular span within which the powder section extends. The area forming the feed section can be related to the position and orientation of the injector guide and the powder injector that applies the powdered additional material to the workpiece. The division of the powder section and the feed section can also cause gaps in the powder caustics, which further facilitates different process zones. The division into a powder section and a feed section enables a welding process that is free of the aforementioned drawbacks.

[0027] In one embodiment, a process gas unit for guiding process gas is arranged radially outside the light tunnel, wherein the process gas unit forms a process gas segment in the circumferential direction, which occupies the feed segment. The process gas unit can be radially outside the light tunnel, relative to the longitudinal direction of the jet nozzle, and can be part of an outer structure that encloses the light tunnel in a closed manner. The process gas can positively influence powder caustics and the resulting workpiece machining. The process gas unit can be a portion of the jet nozzle that is designed to directly or indirectly guide the process gas. The process gas unit can have an additional injector guide into which an additional injector can be inserted. It can also have an annular gap within which the process gas is guided. At the nozzle opening, the process gas unit forms a process gas segment in the circumferential direction around the light tunnel. The process gas unit can be part of the nozzle opening. In a top view, the process gas segment can extend at least partially along the opening of the light tunnel. The process gas segment can be the portion of the process gas unit from which the process gas is emitted from the jet nozzle. The process gas section can connect circumferentially to the powder section at the nozzle mouth. Thus, the process gas section can directly adjoin the powder section circumferentially. This allows the process gas to stabilize powder caustics and continuous laser cladding welding. The process gas section can connect to the powder section, creating a circumferential transition so that an inner section is separated from an outer section by the process gas and powder sections. This separation can be configured to minimize fluid exchange between the inner and outer sections. This helps stabilize the process zone and simultaneously prevents powder particles from adhering to the end faces of the jet nozzle, thereby increasing the jet nozzle's service life.

[0028] In one embodiment, the jet nozzle is manufactured by means of an additive manufacturing method, in particular by means of powder bed fusion. 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 methods on the one hand and ensures sufficient strength, thermal conductivity and heat resistance to meet the process requirements on the other hand. In powder bed fusion, the material to be processed is in the form of a powder. A laser beam heats the powder along the set geometry, whereby the powder liquefies and forms a material bond. For example, powder bed fusion can be formed using selective laser melting (SLM) or selective laser sintering (SLS). The jet nozzle can be made of a non-ferromagnetic material and / or a material that cannot be ferromagnetized.

[0029] In one embodiment, the nozzle mouth has a beveled portion A portion of the nozzle opening is removed by the bevel, which is essentially planar and extends in a plane inclined relative to the longitudinal direction of the jet nozzle. The bevel can cut the powder section and the powder-free feed section or process gas section circumferentially around the light channel. The bevel reduces the volume of the nozzle opening compared to embodiments without a bevel. This means that the nozzle opening takes up less construction space. Jet nozzles with a bevel can be used, for example, to coat brake disks that have a receptacle, i.e., a boss, that protrudes axially relative to the functional surface to be coated. The bevel ensures that the jet nozzle can be moved flexibly over the functional surface to be coated and can be moved close to the receptacle. In the distal region, the bevel can extend in a bypass pattern beside a strip hole or a circular opening. The bypass path defines the orientation of the bevel on the nozzle opening. On the end face of the jet nozzle facing the workpiece, the bypass path extends along a straight line or arc that neither intersects nor contacts the strip hole. The distance between the bypass path and the center point of the light channel is greater than the distance between the corresponding section of the strip-shaped hole and the center point of the light channel. The distance between the bypass path and the outer edge of the strip-shaped hole is selected so that the wall thickness therebetween ensures sufficient strength and load-bearing capacity of the jet nozzle. The nozzle mouth may also have two bevels, arranged symmetrically on the nozzle mouth. In particular, the bevel is provided on the side of the nozzle mouth facing the boss cap to increase the lateral angle of attack of the jet nozzle relative to the perpendicular to the workpiece surface.

[0030] In one embodiment, the process gas unit forms at least one outlet opening on the end face of the jet nozzle, through which process gas can be conducted to the workpiece. An additional injector is arranged in the at least one outlet opening, which is used to supply process gas rather than additional material. The outlet openings can be configured on the end face to minimize the surface to which hard material particles can adhere. The process gas conducted from the outlet openings can be supplemented by process gas conducted within the light tunnel. An additional injector can be arranged in each outlet opening. The additional injectors are distinct from the injectors arranged in the injector guide of the powder unit. While the latter deliver hard material particles to the workpiece surface, the former delivers process gas.

[0031] In one embodiment, the process gas segment extends at least partially along the strip hole arc around the light channel, particularly in an arc shape. Similar to a circular arc, the strip hole arc represents a line enclosing the strip hole in the lobe region. The remaining portion of the strip hole not covered by the strip hole arc can be filled with a powder segment, along which the process gas segment extends. The process gas segment can extend at least partially along a circular arc segment, particularly a circular arc segment located at the front in the feed direction, to form an arc shape. This also helps stabilize the laser beam guidance and / or powder caustics.

[0032] In one embodiment, the process gas segment extends circumferentially around the light channel over an angle between 5° and 180°, particularly between 45° and 120°, relative to the center of the light channel. This allows the process gas segment to extend over a smaller segment around the light channel than the powder segment. This ensures a satisfactory powder supply via the powder unit, and particularly the injector arranged therein, while preventing adhesion or diffusion of the vapor flame. Precise adaptation of the powder segment and process gas segment to the respective process conditions enables flawless and efficient welding.

[0033] In one embodiment, the process gas segment and the powder segment together completely surround the light channel in the circumferential direction, i.e., completely enclosing the light channel through 360°. Consequently, the beam emitted from the process gas segment and the powder segment can separate an inner portion formed within the beam from an outer portion formed outside the beam. This prevents the metal vapor flame, also known as a vapor flame, generated by the interaction of the powder particles with the laser beam from escaping the inner portion, thereby preventing undesirable interaction of the vapor flame with the workpiece.

[0034] In one embodiment, the end side of the beam nozzle, or the end side in the above embodiments, extends at an angle relative to the longitudinal axis of the light channel (along which the laser beam extends), so that the end side is configured to extend substantially parallel to the plane of the workpiece surface. Thus, when extending at an angle, the distance from the nozzle opening to the workpiece can be increased. This reduces the thermal load on the nozzle opening. Furthermore, the angled end side enables improved coverage of the workpiece by the shielding gas. This is because the plane-parallel surfaces of the end side enable a shielding gas flow to be emitted orthogonally to the workpiece. In one embodiment, the beam nozzle is adapted to guide the laser beam along the longitudinal direction of the beam nozzle, so that the at least one laser beam extends orthogonally to the cross-section. Furthermore, the light channel can be adapted to guide the shielding gas in a radially outer section to shield the process zone.

[0035] In one embodiment, the present disclosure further relates to a system comprising a jet nozzle according to the present disclosure and a workpiece. The jet nozzle is tilted about a feed axis (along which the feed direction extends) to form a lateral angle of attack relative to the workpiece, such that, in a plane extending perpendicular to the feed direction, the longitudinal axis of the optical path (along which the laser beam extends) deviates from a perpendicular line to the workpiece surface. The lateral tilt can be achieved by relative movement of the jet nozzle relative to the workpiece or relative movement of the workpiece relative to the jet nozzle. For example, the workpiece support can be tilted relative to the jet nozzle. The lateral tilt can be selected so that the flow balance of the individual streams of the powder jet is optimized when applying the functional layer. The system can include a powder injector. A powder injector can be inserted into each injector guide. In particular, the jet nozzle and / or the powder injector are made of a non-ferromagnetic material or a material that cannot be ferromagnetized.

[0036] In one embodiment, the lateral angle of attack is between 2° and 45°, in particular between 5° and 30°, and even more particularly between 10° and 25°. At these angles of attack, a smooth functional layer without ripples can be efficiently achieved. In the case of an opposing arrangement of the injector guides, these angles of attack further contribute to avoiding defects in the functional layer. It has also been found that at these angles of attack, an ideal compromise is achieved between absorption of reflected radiation by the beam nozzle and the welding behavior of the laser cladding weld.

[0037] In one embodiment, at least one, in particular each, of the plurality of injector guides, in particular the first and / or second injector guides, is tilted relative to the longitudinal axis of the light tunnel in a plane extending perpendicular thereto in the feed direction, preferably at an injector angle of between 10° and 25°. The sum of the lateral angle of attack and the injector angle is configured such that the injector guide tilted toward the workpiece encloses a workpiece angle with the workpiece of at most 30°, in particular at most 45°, and even more particularly at most 50°. This sum of the lateral angle of attack and the injector angle results in the injector guide tilted toward the workpiece having a later / smaller angle with the workpiece than the other injector guides. If the workpiece angle of the injector guide tilted toward the workpiece is too sharp, the functional layer applied by the injector may be affected. Therefore, in this embodiment, the workpiece angle should not be less than 30°. In particular, the lateral angle of attack and the injector angle are adapted to each other so as not to fall below this workpiece angle. In this way, an optimum ratio of high-quality functional layer, functional layer applied close to the hub cup and efficient processing time can be achieved.

[0038] The present invention also relates to a method for laser cladding welding in a feed direction, in particular with the aid of a beam nozzle or a system according to the present disclosure. The method comprises the step of aligning the beam nozzle with the workpiece. As soon as the beam nozzle is aligned with the workpiece, the laser cladding welding process can begin. The method further comprises the step of tilting the beam nozzle about a feed axis extending along the feed direction so that the beam nozzle forms a lateral angle of attack of less than 90° relative to the workpiece in a plane perpendicular to the feed direction. In this way, it is ensured that the beam nozzle can be moved close to the hub cup, for example. In particular, in combination with the beam nozzle according to the present disclosure and an opposing injector, the method is suitable for achieving a smooth and large-area functional layer on a brake disc having a hub cup.

[0039] In one embodiment of the method, the jet nozzle is tilted so that the injector guide, which is tilted toward the workpiece, forms a workpiece angle of at most 30°, particularly at most 45°, and even more particularly at most 50°. If the workpiece angle of the injector guide, which is tilted toward the workpiece, is too sharp, the functional layer applied by the injector may be affected. Therefore, in this embodiment, the workpiece angle should be no less than 30°. This way, an optimal combination of high-quality functional layers, application of the functional layer close to the hub, and efficient processing time can be achieved.

[0040] The features according to the present disclosure overcome the disadvantages of laser cladding welding mentioned at the outset partly individually and partly in combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The preferred further embodiments of the present invention are described in more detail by the following description of the accompanying drawings. In the accompanying drawings:

[0042] Figure 1 shows a schematic diagram of a beam nozzle during laser cladding welding;

[0043] Figure 2 A side view of the jet nozzle is shown;

[0044] Figure 3 Shown Figure 2 A perspective view of the jet nozzle in FIG.

[0045] Figure 4 Shows connections to other components Figure 2 The jet nozzle in

[0046] Figure 5 Shown Figure 2 A top view of the distal end region of the jet nozzle in FIG.

[0047] Figure 6 Shown Figure 2 A top view of a flange section of the jet nozzle in FIG.

[0048] Figure 7 Shown Figure 2 Another perspective view of the jet nozzle in FIG;

[0049] Figure 8 Shown Figure 2 A perspective cross-sectional view of the jet nozzle in FIG.

[0050] Figure 9 A jet nozzle in a further embodiment is shown in a top view of the distal region;

[0051] Figure 10 A jet nozzle with a process gas unit is shown in a top view of the distal region;

[0052] Figure 11 shows another perspective sectional view of a jet nozzle with an angled end face;

[0053] Figure 12 A further embodiment of a jet nozzle with a geometrically adapted nozzle opening is shown in a side view; and

[0054] Figure 13 A further embodiment of a jet nozzle having a first powder section and a second powder section is shown;

[0055] Figure 14 Shown Figure 13 A top view of the embodiment shown in FIG;

[0056] Figure 15 A further embodiment of a jet nozzle having a first powder section and a second powder section is shown;

[0057] Figure 16 Shown Figure 15 A top view of the embodiment shown in FIG; and

[0058] Figure 17 A jet nozzle with a chamfered portion that is moved close to the hub cap of a brake disc is shown. DETAILED DESCRIPTION

[0059] The preferred embodiments are described below with reference to the accompanying drawings. In different figures, identical, similar or functional elements are provided with identical reference numerals, and repeated descriptions of these elements are partially omitted to avoid redundancy.

[0060] Figure 1A beam nozzle 1 for laser cladding welding along a feed direction 2 is shown. The feed direction 2 is the direction along which the beam nozzle 1 moves relative to the workpiece 100. The feed direction can be caused by: a movement of the workpiece 100, in particular a rotational movement; a movement of the beam nozzle 1; or a superposition of movements of the workpiece 100 and the beam nozzle 1. The feed direction 2 and the associated feed movement can be constant during the process flow. Alternatively, they can vary with the respective process phase. The workpiece 100 can be a rotationally symmetrical workpiece, such as a brake disc, a hydraulic cylinder, a pressure roller or a sliding bearing. At least one laser beam 110 emerges from a light channel 3 having a circumferential side 4. The light channel 3 can also be adapted to guide a process shielding gas 150 in a radially outer section in order to shield the process zone and avoid oxidation. The light channel 3 is surrounded by an outer structure 5, which has a nozzle mouth 6, which in turn contains a powder unit 7. For example, the powder unit 7 can have a plurality of injector guides 19 (see Figure 3 ), a powder injector 16 can be inserted into each of the plurality of injector guides (see Figure 4 ). As an alternative to the individual injector guides 19, the powder unit 7 can have a powder annular gap channel. Powdered additional material 120 is directed onto the workpiece 100 via the powder unit 7 and the powder injector 16 arranged in the powder unit 7. 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 additional material 120, which includes hard material particles and a base material. For this reason, the laser beam 110 can have a reduced core strength. Once the molten pool 130 cools, a welded functional layer 140, such as a wear protection layer, is formed from the hard material particles and the base material. The welded functional layer 140 makes the material surface more durable and improves the load-bearing capacity of the material surface.

[0061] Figure 2 The jet nozzle 1 is shown in a side view, wherein the feed direction 2 points out of the drawing plane. The jet nozzle 1 can be connected to other components of the laser system, such as laser optics or a process adapter, via a flange section 9. A proximal region 10 is connected to the flange section 9. A coolant inlet 13 and a coolant outlet 14 are part of the cooling system of the jet nozzle 1 and protrude radially from the jet nozzle 1, the coolant inlet and the coolant outlet being at least partially arranged 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. In the circumferential direction around the light channel 3, the nozzle mouth 6 partially has a powder section 11, in which the powder unit 7 is arranged. In the circumferential direction, a feed section 12 without a powder unit is connected to the powder section 11. The feed section 12 can be designed as a process gas section 61 (see, for example, Figure 9 ), the process gas section is a component of the process gas unit 60.

[0062] Figure 3 Shown Figure 2 1 . The light channel 3 is a hollow channel with a circumferential surface 4, within which the at least one laser beam 110 extends. The outer structure 5 surrounds the light channel 3 from the flange section 9 to the distal region 10. The nozzle opening 6 is a substantially funnel-shaped region of the jet nozzle 1. The funnel shape of the nozzle opening 6 serves in particular to enable the nozzle opening 6 to form a plurality of injector guides 19 in the region of the powder unit 7. Each powder injector 16 (see Figure 4 ) are inserted into these injector guides 19, and the powder injector 16 directs the powdered additional material 120 onto the at least one laser beam 110 and / or the workpiece 100 in accordance with the process requirements. The powder unit 7 extends along the powder section 11, and the feed section 12 without the powder unit is connected to the powder section in the circumferential direction. The feed section 12 is the following area of ​​the nozzle mouth 6 in which the injector guide 19 is not provided, so that the powdered additional material 120 is not supplied via this section. In one embodiment, the feed section 12 can be formed as a process gas section 61, so that the process gas is supplied via this process gas section. The jet nozzle 1 can be manufactured by means of an additive manufacturing method, in particular by means of powder bed fusion. For this purpose, the jet nozzle 1 can be made of a copper-chromium-zirconium alloy. This is suitable for additive manufacturing methods on the one hand, and on the other hand ensures sufficient strength, thermal conductivity and heat resistance to meet the process requirements. In powder bed fusion, the material to be processed is in powder form. The laser beam heats the powder along the set geometry, liquefies the powder and forms a material bond. For example, powder bed fusion can be achieved using selective laser melting (SLM) or selective laser sintering (SLS).

[0063] Figure 4The jet nozzle 1 is shown with additional components attached. A coupling ring 15 is attached to the flange section 9 and secures the jet nozzle 1 to the attached unit, such as the laser optics system or a process adapter. A powder injector 16 is inserted into the injector guide 19 of the powder unit 7. Powdered additional material 120 is conveyed by means of the powder injectors 16 and applied to the workpiece 100 at a set focal point. Each powder injector 16 can use a different powder focal point relative to one another. Alternatively, the powder injectors 16 can be directed to the same focal point. In the powder section 11, the powder injectors 16 are arranged in the injector guide 19 of the powder unit 7 provided for this purpose. The feed section 12 does not have a powder injector 16. Furthermore, an inlet connection piece 17 is inserted into the coolant inlet 13, and an outlet connection piece 18 is inserted into the coolant outlet 14. These connections connect the coolant inlet 13 and the coolant outlet 14 to the coolant circuit.

[0064] Figure 5 The jet nozzle 1 is shown in a top view of the distal region 8 . The cross section of the light channel 3 , which extends 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 section of the light channel 3 is designed as a strip-shaped hole, with a circular arc segment adjoining each of the two opposing ends of the rectangular section. Two laser beams, a primary beam 111 and a secondary beam 112, are guided within the light channel 3 . The primary beam 111 and the secondary beam 112 can originate from the same fiber optic cable. The provided laser light can be divided into parallel beam clusters using a collimating lens. For example, the beam clusters can be formed from a single laser beam into the primary beam 111 and the secondary beam 112 using a wedge plate. The respective center points of the primary beam 111 and the secondary beam 112 are aligned in the feed direction 2 , offset relative to the center point 20 of the light channel 3 .

[0065] In this example, secondary beam 112 is located upstream (downstream) of primary beam 111 in feed direction 2 and does not interact with the powder caustics. Consequently, secondary beam 112 can be used to preheat workpiece 100 before primary beam 111 and the powdered additional material 120 heated by primary beam 111 are directed onto workpiece 100. Thus, secondary beam 112 creates a first process zone for preheating workpiece 100, while primary beam 111 creates a second process zone for depositing powdered additional material 120 onto workpiece 100. These different process zones enable flawless welding without defects, particularly bonding defects, porosity, cracks, and / or dissolution of carbides in the base material. Alternatively, secondary beam 112 can be directed upstream (behind) primary beam 111 in feed direction 2. Thus, the secondary beam 112 may be used to provide additional heating to the workpiece 100, thereby facilitating more uniform cooling that avoids the formation of inclusions or other defects.

[0066] The main beam 111 and the secondary beam 112 are arranged in close proximity to each other. The arc segment of the strip-shaped hole in front in the feed direction 2 is concentric with the secondary beam 112, while the arc segment of the strip-shaped hole in the back is concentric with the main beam 111. The center point of the cross section is eccentric (non-concentric) with the center point of the main beam 111 and the center point of the secondary beam 112. A third beam can also be provided so that, for example, the secondary beam is arranged in front of the main beam in the feed direction and the third beam is arranged behind the main beam in the feed direction. The individual laser beams are guided without blocking each other, so that there is exactly one light channel 3 and exactly one circumferential side surface 4, thereby minimizing heat losses.

[0067] because Figure 5 In the embodiment, primary beam 111 is arranged behind secondary beam 112 in feed direction 2 without radial offset, and secondary beam 112 is used to preheat the workpiece. Therefore, it is desirable that the powdered additional material does not interact with secondary beam 112. This ensures, on the one hand, that secondary beam 112 can perform only the function of preheating the workpiece, and, on the other hand, that the powdered additional material is heated only by primary beam 111 and not by secondary beam 112. This is achieved by forming the powder unit 7 in the region of the nozzle opening 6 such that the powder unit forms a powder section 11 circumferentially around the optical channel 3, with a feed section 12, which is free of powder units, adjoining the powder section 11 in the circumferential direction. In addition to the powder unit 7, a process gas unit 60 may also be provided, forming a process gas section 61, with the feed section 12 being formed as the process gas section 61. The feed section 12 is formed in the region of the nozzle opening 6 facing the feed direction 2. Powder segment 11 extends along the strip-shaped aperture that forms the cross-section of light channel 3 in distal region 8. Similar to a circular arc, powder segment 11 extends around light channel 3 along the strip-shaped aperture arc, particularly in the shape of a horseshoe. Consequently, powder segment 11 extends circumferentially around light channel 3 at a wrap angle that is less than 360°, particularly between 90° and 330°, and even more particularly between 180° and 300° relative to the center point of the light channel. This ensures that the powdered additional material flowing from injector 16 inserted into injector guide 19 interacts only with primary jet 111. Consequently, secondary jet 112 can form a process zone independent of primary jet 111. In a top view, powder segment 11 and feed segment 12 form a strip-shaped aperture. This also helps reduce or avoid the drawbacks mentioned above.

[0068] Figure 6The jet nozzle 1 is shown in a top view of the flange section 9. The cross section of the light channel 3, which extends 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 elongation of the cross section can decrease from the distal region 8 to the flange section 9. In the region of the nozzle opening 6, the cross section can be elongated so that it is at least 1.5 times larger, in particular at least twice as large, in the feed direction transversely thereto. The flange section 9 has such a radial extent that the injector guide 19 is not visible from a top view of the proximal region 10.

[0069] Figure 7 The jet nozzle 1 is shown in another perspective view. The nozzle mouth 6 has a domed funnel shape. Within each dome are formed injector guides 19, into which the powder injector 16 can be inserted. In the feed direction 2, the light channel is elongated, deviating from a circular shape, to achieve the advantages of the present disclosure. The nozzle mouth 6 includes a powder unit 7 circumferentially around the light channel 3. The powder unit 7 extends circumferentially around the light channel 3 along a powder section 11, which is joined by a powder-free feed section 12.

[0070] Figure 8 The figure shows a perspective sectional view of the jet nozzle 1. The light channel 3 has a conical shape, so that the cross section of the light channel 3, which extends 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 from the jet nozzle 1 in the radial direction. Figure 8 A cross-sectional view of an injector guide 19 is shown. The injector guide 19 is arranged in the powder section 11. No injector guide 19 for guiding the powder jet is provided in the feed section 12. The jet nozzle 1 has a cooling system 30. A cooling medium, such as water, is supplied back to a radially inner cooling chamber 31 via a coolant inlet 13 in the proximal region 10. The cooling medium can be distributed circumferentially around the light channel 3 in the proximal region 10. From the proximal region 10, the cooling medium flows to the nozzle mouth 6. The radially inner cooling chamber 31 is formed at least in the nozzle mouth 6. The radially inner cooling chamber 31 can extend from the distal region 8 to the proximal region 10 and be designed as an annular gap segment extending around the light channel 3. In the region of the nozzle mouth 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 opening 6 and is concentric with the light duct 3 in a cross section extending orthogonally to the longitudinal direction of the jet nozzle 1 .

[0071] A transition 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is provided in the distal region 8. In the radial direction, the radially outer cooling chamber 33 has a radial width in the region of the nozzle opening 6 that decreases toward the distal region 8. The radially outer cooling chamber 33 extends from the distal region 8 to the proximal region 10, where it supplies 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 an injector guide 19 for guiding the powder jet, so there is sufficient space for the transition 32.

[0072] The radially outer cooling chamber 33 has a cooling structure for increasing the surface area. The cooling structure can be produced by means of additive manufacturing methods. It ensures that the cooling medium contacts the largest possible surface area when returning from the distal region 8 to the proximal region 10, thereby promoting heat dissipation. The cooling structure is optimized to cause the lowest possible pressure loss of the cooling medium. This can be achieved by means of a honeycomb structure 34, such as Figure 8 As shown in .

[0073] Figure 9 A further embodiment of the jet nozzle 1 is shown in a top view of the distal region 8 . The cross section of the light channel 3 , which extends 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 section of the light channel 3 is designed as a strip-shaped hole, with a circular arc segment adjoining each of the two opposite ends of the rectangular section. A primary beam 111 and a secondary beam 112 are guided within the light channel 3 . The respective center points of the primary beam 111 and the secondary beam 112 are aligned in the feed direction 2 , offset relative to the center point 20 of the light channel 3 .

[0074] The primary beam 111 has a beam center point that coincides with the first powder focus 21. The first powder focus 21 is the point at which the ejector of the first powder section 22 is focused. The first powder section 22 forms a first powder caustic. Accordingly, the secondary beam 112 has a beam center point that coincides with the second powder focus 23. The second powder focus 23 is the point at which the ejector of the second powder section 24 is focused. The second powder section 24 forms a second powder caustic. The primary beam 111 and the secondary beam 112 are offset relative to each other in the feed direction 2. Accordingly, the first powder focus 21 is also offset relative to the second powder focus 23. Therefore, the powder unit 7 having the first powder section 22 and the second powder section 24 can form two different powder focuses. Furthermore, the powder mass flow rate delivered from the ejector of the first powder section 22 can differ from the powder mass flow rate delivered from the ejector of the second powder section 24. A gap may be provided between the first powder section 22 and the second powder section 24 so that the powder mass flow applied by the first powder section 22 interacts only with the primary beam 111 and the powder mass flow applied by the second powder section 24 interacts only with the secondary beam 112 .

[0075] The first and second powder sections 22 and 24 contribute to an increased application rate by creating at least two process zones within the jet nozzle 1. This increases the track width of the applied functional layer. Furthermore, since the shielding gas can be more localized, improved shielding gas coverage is achieved with lower shielding gas consumption.

[0076] The main beam 111 and the secondary beam 112 are arranged adjacent to each other. The leading arc section of the strip hole in the feed direction 2 is concentric with the secondary beam 112, while the trailing arc section of the strip hole is concentric with the main beam 111. The center point 20 of the cross section is eccentric to the center point of the main beam 111 and the center point of the secondary beam 112.

[0077] Figure 10 The jet nozzle 1 is shown in a top view of the distal region 8. A primary beam 111 and a secondary beam 112 are guided in the light channel 3. The secondary beam 112 is ahead of the primary beam 111 in the feed direction 2 and does not interact with the powder caustics, as with the Figure 5As described in more detail, when the laser beam interacts with the material surface and the powder jet, a vapor flame may form between the jet nozzle 1 and the workpiece 100. If this is not restricted, it may interact in an undesirable manner with the at least one laser beam and / or the unprocessed and / or processed material surface. Therefore, in the area adjoining the powder section 11, the feed section 12 can be designed as a process gas section 61. The process gas section 61 is formed by a process gas unit 60 arranged radially outside the light tunnel 3, which directs process gas toward the workpiece. The process gas section 61 prevents undesirable spread of the vapor flame and thus facilitates precise workpiece processing with a robust jet nozzle design. The process gas section 61 can form at least one, and in this example, three, outlet openings 62. The outlet openings 62 are formed on the end face of the jet nozzle 1. Additional injectors for supplying process gas instead of additional material can be inserted into the respective outlet openings 62. The inner diameter of the outlet openings 62 can be smaller than the inner diameter of the injector guide 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 arranged around the strip-shaped opening formed by the light channel 3. As a result, the primary beam 111 and the secondary beam 112 are completely contained within the beam consisting of the powder and process gas beams. The jet nozzle 1 has a plurality of injector guides 19. The injector guide arranged at the end facing away from the feed direction 2 forms the rear injector guide 72.

[0078] Figure 11 The jet nozzle 1 and the workpiece 100 are shown in a longitudinal section. The laser beam 110 extends along the longitudinal axis 43 of the light channel 3. The longitudinal axis 43 of the light channel 3 is tilted at a rearward angle of attack 44 relative to the vertical line 41 of the workpiece surface. The rearward angle of attack 44 describes the tilting of the jet nozzle 1 against the feed direction 2. For example, this rearward tilting can be used to direct the reflected laser beam onto the absorption section. In addition to the rearward tilting, the jet nozzle 1 can also be tilted laterally relative to the workpiece 100, such as with respect to the workpiece 100. Figure 17As further described. The backward angle of attack can be between 2° and 45°, particularly between 10° and 30°, and even more particularly between 15° and 25°. To achieve the tilt or angle of attack 44, the jet nozzle 1 can be tilted relative to the workpiece 100, or the workpiece 100 can be tilted relative to the jet nozzle 1. The surface roughness of the absorption surface of the absorption section is between 5 μm and 100 μm, particularly between 50 μm and 50 μm. The absorption section can also be provided with an absorption coating that promotes absorption. The end side 42 of the jet nozzle 1 can extend at an angle relative to the longitudinal axis 43 of the light channel 3, so that the end side 42 extends plane-parallel to the workpiece 100. This increases the distance from the nozzle opening 6 to the workpiece 100. This reduces the thermal load on the nozzle opening 6. Furthermore, the angled end side 42 improves the shielding gas coverage of the workpiece 100. This is because the plane-parallel surface of the end side 42 allows the shielding gas flow to be emitted orthogonally to the workpiece 100.

[0079] Figure 12 Another embodiment of the jet nozzle 1 is shown. The nozzle mouth 6 has a bevel 50, which cuts off a portion of the nozzle mouth 6. The bevel 50 causes the powder section 11 and the feed section 12, which does not have a powder section, to be cut circumferentially around the light channel 3. The bevel 50 reduces the volume of the nozzle mouth 6 compared to an embodiment without the bevel 50. This ensures that the nozzle mouth 6 takes up less construction space. For example, the jet nozzle 1 with the bevel 50 can be used to coat brake disks. The brake disk 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 moved flexibly over the functional surface to be coated and can be moved close to the receptacle. The bevel 50 can be designed to be essentially planar and extend in a plane inclined relative to the longitudinal direction of the jet nozzle. The bevel 50 forms the boundary surface of the nozzle mouth 6 where the powder unit 7 is not located. In the distal end region 8 , the bevel 50 is arranged close to the light duct 3 , so that no injector guide 19 is provided in the region of the bevel 50 on the end face of the jet nozzle 1 facing the workpiece.

[0080] Figure 13Another jet nozzle 1 is shown in perspective, having a bevel 50. The bevel 50 can extend in the distal region 8 alongside the opening of the light channel 3 in the manner of a bypass 51. The bypass 51 defines the orientation of the bevel 50 at the nozzle opening 6. On the end face of the jet nozzle 1 facing the workpiece, the bypass 51 extends along a straight line or arc that neither intersects nor touches the opening. Additionally, another 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. The distance between the bypass 51 and the center point 20 of the light channel 3 is greater than the distance between the corresponding section of the strip hole and the center point 20 of the light channel 3. The distance between the bypass 51 and the outer edge of the strip hole is selected so that the wall thickness therebetween ensures sufficient strength and load-bearing capacity for the jet nozzle 1.

[0081] The orientation of the bypass path 51, and therefore the orientation of the bevel 50 at the nozzle opening 6, can vary for different jet nozzles 1 depending on the respective application. For example, the bypass path 51 can extend in the feed direction 2. Alternatively, for example, the bypass path 51 can extend transversely to the feed direction 2. Further alternatively, for example, the bypass path 51 can extend at an angle relative to the feed direction 2 that lies between a direction along the feed direction 2 and a direction transversely to the feed direction 2. In this case, the bypass path 51 extends along the transition section between the long side of the strip hole and the circular arc section of the strip hole. The direction of the bypass path 51 predetermines the orientation of the bevel 50.

[0082] The powder unit 7 on the nozzle mouth 6 forms a powder section 11 circumferentially around the light channel 3. The powder section has multiple injector guides 19, each of which can be inserted into a powder injector 16. With respect to the first powder focus 21, the first injector guide 70 is essentially opposite the second injector guide 71. Specifically, the first injector guide 70 and the second injector guide 71 are mirror images at the first powder focus 21. In this embodiment, there are four additional injector guides, two of which are opposite each other. Thus, the jet nozzle in this example has a total of six injector guides, with each injector guide in the first powder section 73 having an opposing corresponding injector guide in the second powder section 74. The opening of the light channel 3 can be an elongated opening in the form of a strip-shaped hole or, as shown, a circular opening.

[0083] Figure 14 Shown Figure 13, wherein a powder injector 16 is inserted into each injector guide 19. The powder injectors extend obliquely relative to the plane of extension of the end face of the jet nozzle 1. Furthermore, each powder injector 16 has an opposing powder injector 16 in a mirror-image manner relative to the first powder focus 21, and the first powder segment 73 is separated from the second powder segment 74 on both sides in the circumferential direction by powder segment recesses.

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

[0085] Figure 17 The jet nozzle 1 is shown directed toward a workpiece 100 having a boss 101 . Figure 17 The drawing plane in is the plane to which the feed direction 2 is perpendicular. The jet nozzle 1 is tilted about the feed axis, along which the feed direction 2 extends. Figure 17 In the embodiment, the jet nozzle 1 is moved to the right flank of the boss cap 101, so that the jet nozzle 1 is tilted to the right about the feed axis. Due to the tilt of the jet nozzle 1 about the feed axis, a lateral angle of attack 45 is formed between the vertical line 41 of the workpiece surface and the longitudinal axis 43 of the light channel. The lateral angle of attack 45 is combined with, for example, Figure 11 The described rearward angle of attack 44 is irrelevant. A lateral angle of attack 45, particularly in combination with a chamfer 50, allows the jet nozzle 1 to approach the boss 101, thereby allowing the functional layer to be applied to the workpiece 100 all the way to the boss 101. If the workpiece 100 is a brake disc, this approach ensures that the entire friction surface of the disc, up to the connection to the boss 101, is provided with the functional layer. The lateral angle of attack 45 can be between 2° and 45°, particularly between 10° and 30°, and particularly between 15° and 25°. In the illustrated plane, one of the plurality of injector guides 19, particularly each of the plurality of injector guides 19, is tilted relative to the longitudinal axis 43 of the light tunnel, with the feed direction 2 extending orthogonally to the plane. In particular, at least one injector guide 19, particularly the first injector guide 70 and / or the second injector guide 71, can be tilted at an injector angle 46 between 10° and 25°.

[0086] The lateral angle of attack 45 indicates the presence of at least one ejector guide 75 that is inclined toward the workpiece 100. The ejector guide 75 that is inclined toward the workpiece 100 can be any of the plurality of ejector guides 19. The workpiece angle 47 extending between the direction of the ejector guide 75 that is inclined toward the workpiece 100 and the workpiece surface is determined by the sum of the lateral angle of attack 45 and the ejector angle 46. It has been found that an excessively sharp workpiece angle 47 can lead to ripples in the applied functional layer. In this regard, the lateral angle of attack 45 and the ejector angle 46 are matched to each other so that the workpiece angle 47 is a maximum of 30°, in particular a maximum of 45°, and in particular a maximum of 50°. At this workpiece angle 47, an optimal ratio between the quality of the functional layer and the proximity of the functional layer to the boss cap 101 is achieved. In other words, at these angles of attack 45 and / or these ejector angles 46, a smooth, ripple-free functional layer can be efficiently achieved. Thus, when the injector guides 19 are arranged opposite one another, the angles of attack 45 and / or the injector angles 46 further contribute to avoiding defects in the functional layer. Furthermore, the chamfer 50 contributes to a flush movement of the jet nozzle 1 close to the boss cap 101 .

[0087] Where applicable, all the individual features presented in the embodiments may be combined with one another and / or interchanged without departing from the scope of the present invention.

[0088] Reference Signs List

[0089] 1 Jet nozzle 33 Radial outer cooling chamber

[0090] 2 Feed direction 34 Honeycomb structure

[0091] 3 Light channel 41 Vertical line of workpiece surface

[0092] 4 side surface 42 end side

[0093] 5 External structure 43 Longitudinal axis of the light channel

[0094] 6 Nozzle mouth 44 Backward angle of attack

[0095] 7 Powder unit 45 lateral angle of attack

[0096] 8 Distal region 46 Injector angle

[0097] 9 Flange section 47 Workpiece angle

[0098] 10 proximal region 50 beveled portion

[0099] 11 Powder section 51 Bypass route

[0100] 12 Feed section 60 Process gas unit

[0101] 13 Coolant inlet 61 Process gas section

[0102] 14 Coolant outlet 62 outlet opening

[0103] 15 coupling ring 70 first injector guide

[0104] 16 Powder injector 71 Second injector guide

[0105] 17 Inlet connection 72 Post-injector guide

[0106] 18 Outlet connection 73 First powder section

[0107] 19 Injector guide 74 Second powder section

[0108] The center 75 of the light channel 20 is inclined close to the ejector guide of the workpiece

[0109] 21 First powder focus 100 Workpiece

[0110] 22 First powder section 110 Laser beam

[0111] 23 Second powder focus 111 Main beam

[0112] 24 Second powder section 112 beams

[0113] 30 cooling system 120 powdered additional materials

[0114] 31 radial inner cooling chamber 130 molten pool

[0115] 32 transition piece 140 functional layer

Claims

1. A beam nozzle (1) for laser cladding welding along a feed direction (2), the beam nozzle comprising: - an optical channel (3) for guiding at least one laser beam, which is directed onto the 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 at least with a first powder focus (21); in, The powder unit (7) forms a powder section (11) on the nozzle mouth (6) around the light channel (3) in the circumferential direction, and the powder section has a plurality of injector guides (19), in which powder injectors (16) can be inserted respectively, wherein, with respect to the first powder focus (21), the first injector guide (70) is basically opposite to the second injector guide (71).

2. The 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 in each case two injector guides of the plurality of injector guides (19) are opposite each other with respect to a center point (20) of the light channel (3).

3. The jet nozzle (1) according to claim 1, wherein: The plurality of injector guides (19) is an odd number, wherein the rear injector guide (72) at the rear in the feed direction (2) is the only injector guide of the plurality of injector guides (19) that does not have an opposing injector guide, or wherein, The plurality of injector guides (19) is an even number, so that each injector guide (19) has an opposing injector guide.

4. The jet nozzle (1) according to claim 1, wherein: The feed direction (2) extends orthogonally relative to a plane in which the first ejector guide (70) and / or the second ejector guide (71) are inclined relative to the longitudinal axis (43) of the light duct (3), preferably at an ejector angle (46) between 10° and 25°.

5. The jet nozzle (1) according to claim 1, 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) is located on a longitudinal axis (43) of the light channel (3) along which the laser beam extends.

6. The jet nozzle (1) according to any one of claims 1 to 4, wherein A first portion of the plurality of injector guides (19) is aligned with the first powder focus (21) and a second portion is aligned with the second powder focus (23), wherein in particular the first powder focus (21) and the second powder focus (23) extend along the feed direction (2) and form a focal line.

7. The jet nozzle (1) according to claim 1, wherein: A first powder injector is inserted into the first injector guide (70) and is ready to deliver a first powder mass flow, and a second powder injector is inserted into the second injector guide (71) and is ready to deliver a second powder mass flow, wherein the first powder mass flow is different from the second powder mass flow, and wherein in particular the first powder mass flow delivers a different powder than the second powder mass flow.

8. The jet nozzle (1) according to claim 1, wherein: The cross section of the light channel (3) extending orthogonally to the longitudinal direction of the jet nozzle (1) is elongated in the feed direction (2) in a manner deviating from a circular shape, and the powder section (11) extends around the light channel (3) along a strip-shaped hole arc, in particular in a horseshoe shape.

9. The jet nozzle (1) according to claim 1, wherein: The powder section (11) includes a first powder section (73) and a second powder section (74), and the first powder section (73) and the second powder section (74) are separated by a powder section gap.

10. The jet nozzle (1) according to claim 1, wherein: The powder section (11) extends around the light channel (3) in the circumferential direction at an angle of circumference (23), which is between 45° and 330°, in particular between 90° and 300°, and further in particular between 180° and 300°, with respect to a center point (20) of the light channel (3).

11. The jet nozzle (1) according to claim 1, wherein: The optical channel (3) is adapted for guiding a plurality of laser beams, wherein the plurality of laser beams comprises a first laser beam as a main beam (111) and a second laser beam as a secondary beam (112).

12. The jet nozzle (1) according to any one of the preceding claims, wherein A feed section (12) without a powder unit is connected to the powder section (11) in the circumferential direction, and the feed section without a powder unit is constructed in an area of ​​the nozzle mouth (6) facing or facing away from the feed direction (2), wherein, in particular, a process gas unit (60) for guiding process gas is arranged radially outside the light channel (3), wherein the process gas unit (60) forms a process gas section (61) in the circumferential direction, which occupies the feed section (12). 13 . The jet nozzle ( 1 ) according to claim 1 , which is produced by means of an additive manufacturing method and contains, in particular, copper or a copper alloy, further in particular a copper-chromium-zirconium alloy.

14. The jet nozzle (1) according to any one of the preceding claims, wherein The nozzle opening (6) has a bevel (50), by which a part of the nozzle opening (6) is cut away, wherein the bevel (50) is substantially planar and extends in a plane which is inclined relative to the longitudinal direction of the jet nozzle (1).

15. A system comprising a jet nozzle (1) according to any one of the preceding claims and a workpiece (100), wherein: The feed direction (2) extends along a feed axis, the beam nozzle (1) is tilted about the feed axis to form a lateral attack angle (45) relative to the workpiece (100), so that: in a plane, the longitudinal axis (43) of the light channel (3) deviates from a vertical line (41) of the workpiece surface of the workpiece (100), the feed direction (2) extends orthogonally to the plane, and the laser beam extends along the longitudinal axis.

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

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

18. A method for laser cladding welding in a feed direction (2), in particular by means of a jet nozzle (1) or a system according to any one of the preceding claims, comprising the following steps: - aligning the jet nozzle onto a workpiece (100); - the jet nozzle (1) is tilted about a feed axis so that the jet nozzle (1) forms a lateral angle of attack (45) of less than 90° relative to the workpiece (100) in a plane, the feed direction (2) extending along the feed axis, the feed direction (2) extending orthogonally to the plane.

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

Images