Jet nozzle with powder section and feed section

Abstract

The invention relates to a jet nozzle (1) for laser deposition welding in a feed direction (2), comprising: a light channel (3) for guiding at least one laser beam, said at least one laser beam being guided onto a workpiece; and a powder unit (7) arranged radially outside the light channel (3) for guiding at least one powder jet applied to the workpiece, the powder unit (7) forming a powder section (11) around the light channel (3) in the circumferential direction at the nozzle opening (6), and the feed section (12) without the powder unit engaging with the powder section in the circumferential direction.

Description

Technical Field

[0001] The invention relates to a jet nozzle for laser deposition welding along a feed direction. Background Art

[0002] Laser deposition welding is used, for example, in the fields of repair, coating, and / or joining technology. A distinction can be made between conventional laser deposition welding techniques (laser metal deposition (LMD), direct metal deposition (DMD), or direct energy deposition (DED)) and so-called high-speed laser deposition welding (HS-LMD) or ultra-high-speed laser applications (EHLA). The HS-LMD method is described, for example, in the published patent applications DE 10 2011 100 456 A and DE 10 2018 130 798 A1. Another method for laser deposition welding is known from the Chinese patent application CN 109175372 A.

[0003] Laser deposition welding can be used to apply functional layers to workpieces. This generally results in an increase in the load-bearing capacity of workpieces treated with laser deposition welding compared to untreated workpieces. The functional layer can, for example, serve as a wear protection layer. Application of the functional layer involves melting the workpiece surface, applying a powdered filler material, and subsequent cooling, resulting in a material-to-material connection between the matrix structure containing hard material particles and the material surface. Laser deposition welding thus affects and alters the internal material structure of the workpiece. In some cases, this can cause defects in the internal material structure, which can impair the desired increase in load-bearing capacity. These defects can be microscopic in nature and therefore only detectable with considerable effort. Summary of the Invention

[0004] Based on the known prior art, the present invention aims to provide an improved jet nozzle for laser deposition welding in the feed direction. In particular, the present invention aims to improve the overall weld quality of the applied functional layer and the workpiece, and to reduce or avoid defects in the welded connection between the powdered filler material and the material surface. Defects can be defects in the bond between the material surface and the applied functional layer, or between individual applied functional layers. Defects can also be pores, i.e., air pockets, that appear within the applied functional layer or between the applied functional layer and the material surface. In particular, pores may occur more frequently when the material surface is a cast material. Defects can also be cracks within the applied functional layer that extend perpendicular to the material surface. Defects can also be caused by the dissolution of powder particles, especially carbides, of the powdered filler material in the matrix material of the powdered filler material, which leads to brittleness of the matrix material. The present invention also aims to provide a reliable jet nozzle that is resistant to thermal loads. The present invention can also aim to design the jet nozzle so that it ensures reliable and precise laser deposition welding over very 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] Therefore, a jet nozzle for laser deposition welding along a feed direction is proposed. The jet nozzle includes an optical channel for guiding at least one laser beam, which is directed onto a workpiece. Laser deposition welding can be a method used for high-speed laser metal deposition (HS-LMD). The feed direction is the direction along which the jet nozzle moves relative to the workpiece. This feed direction can be caused by: movement, in particular rotation, of the workpiece; movement of the jet nozzle; or a combination of both. The feed direction and the associated feed motion can be constant during the process. Alternatively, they can vary with the respective process stage. 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 by an optical cable to a laser system. The laser system splits the laser beam via a collimator lens and focuses the laser beam according to the process using laser optics before the laser beam enters the jet nozzle. The optical channel can be a hollow channel extending longitudinally through the entire jet nozzle. In addition to the laser beam, process gases can also be guided to the workpiece surface via optical channels.

[0007] The jet nozzle further comprises a powder unit, which is arranged radially outside the light channel and is used to guide at least one powder jet to be applied to the workpiece. Starting from the longitudinal direction of the jet nozzle, the powder unit can be radially outside the light channel and can be part of an outer structure that closes around the light channel. The powder jet can guide a powdered filler material consisting of hard material particles, in particular carbides, and a matrix material. The powder unit can be part of a jet nozzle designed to guide the powdered filler material directly or indirectly. The powder unit can have an injector guide device, into which a powder injector can be inserted. The powder unit can also have an annular gap, into which the powdered filler material is guided.

[0008] The powder unit forms a powder segment at the nozzle opening in a circumferential direction around the light channel, and a feed segment without a powder unit is connected to the powder segment in the circumferential direction. The powder unit can be part of the nozzle opening. The nozzle opening is the part of the jet nozzle facing the workpiece. The end segment of the nozzle opening has a distal region. The distal region is the part of the nozzle opening closest to the workpiece. In the segment facing away from the workpiece, the jet nozzle has a proximal region and a flange segment. The proximal region and the flange segment are the parts of the jet nozzle facing away from the workpiece. The nozzle can be coupled to another component of the laser system, such as a laser optical device or a processing unit, via the flange segment. The powder segment and the feed segment can together form the entire circumference of the nozzle opening around the light channel. For example, the powder segment can constitute a larger portion than the feed segment. In a top view, the powder segment and the feed segment can extend in a closed manner along the opening of the light channel.

[0009] Thus, a jet nozzle can provide increased variability in: (i) laser beam guidance; (ii) the use of powdered filler material; (iii) thermal management; and / or (iv) protection of the laser system including the jet nozzle. The jet nozzle enables the establishment of multiple independent processing zones with high precision. The processing zone can be divided into a zone for laser deposition welding and a zone for pre-treatment and / or post-treatment. In the zone for laser deposition welding, interaction occurs between at least one laser beam and the powdered filler material. The pre-treatment and / or post-treatment can include cleaning the material surface, pre-heating the material surface before applying the powdered filler material, post-heating the material surface after the powdered filler material has been applied, or a combination thereof. During the pre-treatment and / or post-treatment, the laser beam can strike the workpiece without interacting with the powdered filler material. Independent processing zones can 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 can stabilize the processing zone and improve the precision of the laser deposition welding and the service life of the jet nozzle.

[0010] In particular, jet nozzles can reduce the occurrence of joint defects. This is because joint defects can occur if the surface heated by the laser beam, such as a workpiece or a previously welded functional layer, is not sufficiently heated. This insufficient heating can be caused by keeping the laser power of the individual laser beams low to avoid overheating the powdered filler material. Due to increased variability in laser beam guidance, increased variability in the use of powdered filler material, and / or increased variability in the thermal management of the jet nozzle, the occurrence of joint defects can be reduced or even avoided. This can be achieved, in particular, by dividing the jet nozzle into a powder section and a feed section, thereby enabling the provision of multiple treatment zones.

[0011] In particular, the jet nozzle can also reduce the occurrence of holes between the welded functional layer and the surface heated by the laser beam. This is because holes can form when sheet elements in the workpiece, in particular graphite sheets, 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. Due to increased variability in the guidance of the laser beam, increased variability in the application of the powdered filler material, and / or increased variability in the thermal management of the jet nozzle, the occurrence of holes can be reduced or even avoided, in particular by dividing the jet nozzle into a powder section and a feed section, thereby enabling the provision of multiple processing zones.

[0012] In particular, jet nozzles can also 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 filler material and the less intensely heated workpiece surface is so strong that the material contraction that occurs during cooling induces stresses that cause cracks. Crack formation can be caused by setting the laser power of a single laser beam too high to avoid joint defects caused by insufficient heating. Due to increased variability in the guidance of the laser beam, increased variability in the application of the powdered filler material, and / or increased variability in the thermal management of the jet nozzle, the occurrence of cracks can be reduced or even avoided, in particular by dividing the jet nozzle into a powder section and a feed section, thereby enabling the provision of multiple treatment zones.

[0013] In particular, the jet nozzle can also reduce the dissolution of hard material particles, especially carbides, in the matrix material. The powdered filler material can contain hard material particles, especially carbides, and matrix 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 filler material is exposed to excessively high radiation levels, causing the hard material particles to melt, the hard material particles may dissolve. Because the matrix material has a low ductility, the dissolved hard material particles cause the welded functional layer to become brittle. As a result, stresses caused by, for example, contraction, cannot be absorbed by the matrix material when the workpiece cools or is loaded. Due to increased variability in laser beam guidance, increased variability in the application of the powdered filler material, and / or increased variability in the thermal management of the jet nozzle, the dissolution of hard material particles can be reduced or even avoided. This can be achieved, in particular, by dividing the jet nozzle into a powder section and a feed section, thereby enabling the provision of multiple treatment zones.

[0014] 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 plume could cause the filler material to adhere to or even weld to the nozzle opening, which could disrupt the gas and powder flows and subsequently impair the process result. The metal vapor plume is the result of the partial vaporization of the material caused by laser deposition welding. This can lead to scattering and / or absorption of the laser radiation, thereby impairing the preheating of the workpiece. This can further promote the formation of joining defects. Due to the increased variability in the laser beam guidance, the increased variability in the application of the powdered filler material, and / or the increased variability in the thermal management of the jet nozzle, the undesirable dissolution of hard material particles and the spread of the metal vapor plume can be reduced or even avoided. This is achieved, in particular, by dividing the jet nozzle into a powder section and a feed section, thereby enabling the provision of multiple processing zones.

[0015] At least one laser beam, particularly at least one circular and / or elliptical laser beam, can be guided within the nozzle opening so that it interacts with the powdered filler material, forming more than one treatment zone. This promotes welding behavior, reduces the occurrence of defects in the welded joint, particularly joint defects, pores, cracks, and / or dissolution of carbides in the matrix material, and increases the load-bearing capacity of the applied functional layer. The melting behavior, powder jet behavior, material-to-material connection, and cooling behavior can thus be variably adapted to the respective application and the corresponding material properties and processing parameters. In particular, excessive laser power can be prevented from being applied to the powdered filler material. Consequently, the powdered filler material is not overheated during interaction with the laser beam, which, for example, prevents vaporization and powder loss. Furthermore, the feed zone results in smaller temperature gradients in the melted material, resulting in less shrinkage and lower internal stresses, which prevents the occurrence of cracks in the functional layer. The division of the powder and feed zones also creates gaps in the powder caustics, further facilitating the different treatment zones. The division into a powder section and a feed section makes it possible to achieve a welding process that does not have the aforementioned drawbacks.

[0016] In one embodiment, the feed section is configured in the area of ​​the nozzle opening facing the feed direction. In a top view, the area of ​​the nozzle opening facing the feed direction is located at the end of the nozzle proximal to the feed direction. The end face of the feed section points toward the workpiece. The feed section can extend circumferentially around the light channel within a certain angular range. The angular range within which the feed section extends can be smaller than the angular range within which the powder section extends. The area in which the feed section is configured can be related to the positioning and orientation of the powder injector that applies the powdered filler material to the workpiece.

[0017] In one embodiment, the powder segment extends around the light channel along an elongated aperture arc, particularly an elongated aperture arc in the shape of a horseshoe. Similar to a circular arc, an elongated aperture arc represents a line that encloses the elongated aperture in a sector-like manner. The remaining portion of the elongated aperture not enclosed by the elongated aperture arc can be occupied by the feed segment, along which the powder segment extends. The powder segment can extend at least partially along the two opposing straight ends and the partially circular section in the middle of the elongated aperture, forming a horseshoe shape. This further facilitates the provision of more than one processing zone.

[0018] In one embodiment, the powder section extends in the circumferential direction around the light channel at a wrap angle relative to the center point of the light channel, which wrap angle is between 45° and 330°, in particular between 90° and 300°, and further in particular between 180° and 300°. As a result, the powder section can extend around the light channel by a larger section than the feed section. As a result, a satisfactory powder supply can be ensured by the powder unit and in particular the injector arranged therein. The precise adjustment of the powder section and the feed section to the respective process conditions enables an efficient welding process without defects. In particular, if the nozzle opening has an inclined portion, the nozzle opening can be opened. By cutting off a part of the nozzle opening through the inclined portion, the surrounding angle of the powder section is between 90° and 180°. If the nozzle opening does not have an inclined portion, the nozzle opening is preferably above 180°.

[0019] In one embodiment, the powder segment is composed of a first powder segment and a second powder segment, and the first powder segment is separated from the second powder segment by a powder segment gap. The powder segment gap can be different from that of the feed segment. By composing the powder segment from multiple individual powder segments, the variability of the jet nozzle is further taken into account. The composition of the powder segment can be determined by interaction with the configuration of the laser beam or multiple laser beams.

[0020] In one embodiment, the powder segment gap is formed in the region of the nozzle opening facing away from the feed direction. Thus, the feed segment can be arranged facing the feed direction, and the powder segment gap can be arranged facing away from the feed direction. Particularly when the light channel guides more than one (particularly three) laser beams, the powder segment can be divided into multiple powder segments interacting with the feed segment, and the powder segment gap can further contribute to achieving efficient, flawless welding behavior with the jet nozzle.

[0021] In one embodiment, the powder section has multiple injector guides, each of which can be inserted into a corresponding powder injector. The injector guides can be cylindrical or conical through-holes in the nozzle opening, into which the powder injectors can be inserted. The injector guides can be introduced into the nozzle opening by machining. However, they are preferably installed during the additive manufacturing phase of the jet nozzle. The injector guides can be adapted to the powder injectors used.

[0022] In one embodiment, a first powder injector is configured to deliver a first powder mass flow and a second powder injector is configured 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 arranged in a first powder section and the second powder injector can be arranged in a second powder section. The first powder injector can be arranged so that the first powder injector interacts with a primary beam of the laser beam. The second powder injector can be arranged so that the second powder injector interacts with a secondary beam of the laser beam. The primary beam and the secondary beam can be identical to each other or transmit different energies. The arrangement of the first powder mass flow and the second powder mass flow enables the jet nozzle to achieve more than one treatment zone, which further helps to increase the variability of the jet nozzle.

[0023] In one embodiment, the first powder mass flow delivers a different powder than the second powder mass flow. This allows functional layers with variable materials to be applied to the workpiece. Alternatively, the first and second powder mass flows can direct the same powder to the workpiece. Adjusting the powder mass flow to the respective injector further contributes to increased variability.

[0024] In one embodiment, a first powder injector is configured to form a first powder focus and a second powder injector is configured to form a second powder focus, wherein the first powder focus is different from the second powder focus. The powder focus can be the location where the powder jet hits the workpiece. The powder focus is located in a radial direction within the cross section of the light channel. Multiple first powder injectors can be adjusted to form the first powder focus, and similarly, multiple second powder injectors can be adjusted to form the second powder focus. Thus, for example, a first laser deposition and a second laser deposition offset relative to the first laser deposition along the feed direction can be welded to the workpiece. The adjustment of the powder focus can be performed according to the respective workpiece or the respective process and further contributes to increased variability.

[0025] In one embodiment, the powder segment forms an annular gap segment, in particular replacing an ejector guide. The annular gap segment can form a uniform powder focus, for example, which coincides with the center point of at least one laser beam. With the annular gap segment, the powdered filler material is applied to the workpiece along a horseshoe-shaped jet.

[0026] 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 processing requirements on the other hand. In powder bed fusion, the material to be processed is in powder form. A laser beam heats the powder along the provided geometry, liquefies the powder and connects it in a material-locking manner. For example, powder bed fusion can be formed using selective laser melting (SLM) or selective laser sintering (SLS).

[0027] In one embodiment, the nozzle opening includes an inclined portion, through which a portion of the nozzle opening is cut away. The inclined portion is substantially planar and extends in a plane inclined relative to the longitudinal direction of the jet nozzle. The inclined portion can cut away a powder section and a powder-free feed section circumferentially surrounding the light channel. The inclined portion reduces the volume of the nozzle opening compared to embodiments without an inclined portion. This means that the nozzle opening takes up less installation space. A jet nozzle with an inclined portion can, for example, be used to coat brake disks having a receiving portion protruding axially from the functional surface to be coated. The inclined portion ensures that the jet nozzle can be flexibly moved over the functional surface to be coated and can be moved closer to the receiving portion. The inclined portion can extend in the distal region of the elongated hole like a bypass. The bypass defines the orientation of the inclined portion on the nozzle opening. On the end face of the jet nozzle facing the workpiece, the bypass extends along a straight line or arc that neither intersects nor contacts the elongated hole. The distance between the bypass and the center point of the light channel is greater than the distance between the corresponding section of the elongated hole and the center point of the light channel. The distance between the bypass and the outer edge of the elongated hole is selected such that the wall thickness therebetween ensures sufficient robustness and load-bearing capacity of the jet nozzle.

[0028] In one embodiment, the jet nozzle is adapted to direct the laser beam along a longitudinal direction of the jet nozzle such that the at least one laser beam extends orthogonally to the cross section. Furthermore, the light channel may be adapted to direct a shielding gas along a radially outer section to protect the processing zone.

[0029] The features according to the present disclosure partly contribute on their own and partly combine to overcome the initially mentioned drawbacks of laser deposition welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Preferred further embodiments of the present invention are explained in more detail by the following description of the accompanying drawings, in which:

[0031] Figure 1 shows a schematic diagram of a jet nozzle during laser deposition welding;

[0032] Figure 2 A side view of a jet nozzle is shown;

[0033] Figure 3 Shown Figure 2 A three-dimensional view of the jet nozzle in FIG;

[0034] Figure 4 Shows connections to other components Figure 2 The jet nozzle in

[0035] Figure 5 Shown Figure 2 A top view of the distal end region of the jet nozzle;

[0036] Figure 6 Shown Figure 2 A top view of the flange section of the jet nozzle in FIG.

[0037] Figure 7 Shown Figure 2 Another perspective view of the jet nozzle in;

[0038] Figure 8 Shown Figure 2 A perspective cross-sectional view of a jet nozzle in FIG.

[0039] Figure 9 Shown Figure 2 Another top view of the distal end region of the jet nozzle in;

[0040] Figure 10 shows a top view of the distal region of the jet nozzle with the process gas unit;

[0041] Figure 11 shows a side view of a further embodiment of a jet nozzle with a geometrically adapted nozzle opening; and

[0042] Figure 12 A plan view of a further embodiment of a jet nozzle with a geometrically adapted nozzle opening is shown. DETAILED DESCRIPTION

[0043] Preferred exemplary embodiments are described below with reference to the accompanying drawings. In this case, in different figures, identical, similar or elements having the same effect are provided with identical reference numerals, and repeated description of these elements is omitted in some instances to avoid redundancy.

[0044] Figure 1A jet nozzle 1 for laser deposition welding along a feed direction 2 is shown. The feed direction 2 is the direction along which the jet nozzle 1 moves relative to the workpiece 100. The feed direction can be caused by: a movement, in particular a rotational movement, of the workpiece 100; a movement of the jet nozzle 1; or a superposition of movements of the workpiece 100 and the jet nozzle 1. During the process, the feed direction 2 and the associated feed movement can be constant. Alternatively, they can change with the respective process stage. 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 side surface 4. The light channel 3 can also be suitable for guiding a process shielding gas 150 along a radially outer section to protect the process zone and prevent oxidation. The light channel 3 is surrounded by an outer structure 5, which has a nozzle opening 6, which in turn contains a powder unit 7. For example, the powder unit 7 can have a plurality of injector guide devices 19 (see Figure 3 ), in each of the plurality of injector guides a powder injector 16 can be inserted (see Figure 4 ). As an alternative to a single injector guide device 19, the powder unit 7 can have a powder annular gap channel. The powdered filler material 120 is guided onto the workpiece 100 via the powder unit 7 and the powder injector 16 arranged in the powder unit. The laser beam 110 heats the workpiece 100 so that a molten pool 130 is formed on the material surface. In addition, the laser beam 110 heats the powdered filler material 120, which includes hard material particles and a matrix material. To this end, the laser beam 110 can have a reduced center portion intensity. Once the molten pool 130 cools, a welded functional layer 140, such as a wear protection layer, is formed by the hard material particles and the matrix material. The welded functional layer 140 makes the material surface more durable and improves the load-bearing capacity of the material surface.

[0045] 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 coupled 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 attached 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, said coolant inlet and said 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 to the proximal region 10. The distal region is a component of the funnel-shaped nozzle opening 6. The nozzle opening has a powder section 11 in a segmented manner around the light channel 3 in the circumferential direction, in which powder units 7 are arranged. A feed section 12 without a powder unit is connected to the powder section 11 in the circumferential direction. The feed section 12 can be configured as a process gas section 61 (see, for example Figure 9 ), the process gas section is a component of the process gas unit 60.

[0046] Figure 3 Shown Figure 2 3D view of the jet nozzle in FIG. The light channel 3 is a hollow channel with a side 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 also serves to enable the nozzle opening 6 to form a plurality of injector guides 19 in the region of the powder unit 7. The powder injector 16 (see Figure 4 ) are respectively inserted into each of these injector guide devices 19, and the powder injector guides the powdered filler material 120 onto at least one laser beam 110 and / or the workpiece 100 depending on the process. 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 opening 6, in which the injector guide device 19 is not provided, so that the powdered filler material 120 is not supplied via this feed 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 provided geometry, thereby liquefying the powder and connecting it in a material-locking manner. For example, selective laser melting (SLM) or selective laser sintering (SLS) can be used to form a powder bed fusion.

[0047] Figure 4The jet nozzle 1 is shown, to which additional components are mounted. A coupling ring 15 is connected to the flange section 9 and secures the jet nozzle 1 to the unit to which it is connected, such as a laser optics system or a processing adapter. A powder injector 16 is inserted into the injector guide 19 of the powder unit 7. Powdered filler material 120 is conveyed by means of the powder injector 16 and applied to the workpiece 100 at a set focal point. Each powder injector 16 can use different powder focal points relative to one another. Alternatively, the powder injectors 16 can be directed to the same focal point. The powder injectors 16 are arranged in the injector guide 19 of the powder unit 7 provided for this purpose in the powder section 11. 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 connectors connect the coolant inlet 13 and the coolant outlet 14 to the coolant circuit.

[0048] 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, perpendicular 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 configured as an elongated hole, with two opposing ends of a rectangular section each connected to a partially circular 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 optical fiber cable. The supplied laser light can be divided into parallel beam clusters using a collimator lens. For example, the beam clusters can be formed from a single laser beam using a wedge plate to form the primary beam 111 and the secondary beam 112. The respective center points of the primary beam 111 and the secondary beam 112 lie on a line offset from the center point 20 of the light channel 3 in the feed direction 2.

[0049] In this example, secondary beam 112 precedes primary beam 111 in feed direction 2 and does not interact with the powder caustics. Thus, secondary beam 112 can be used to preheat workpiece 100 before primary beam 111 and the powdered filler material 120 heated by primary beam 111 strike the workpiece 100. Thus, secondary beam 112 creates a first treatment zone for preheating workpiece 100, while primary beam 111 creates a second treatment zone for welding powdered filler material 120 to workpiece 100. These distinct treatment zones enable flawless welding without defects, particularly joint defects, pores, cracks, and / or dissolution of carbides in the base material. Secondary beam 112 can also be directed after primary beam 111 in feed direction 2. Thus, secondary beam 112 can be used to reheat workpiece 100, thereby facilitating more uniform cooling that prevents the formation of inclusions or other defects.

[0050] The primary beam 111 and the secondary beam 112 are arranged in close proximity to one another. The front subcircular section of the elongated hole in the feed direction 2 is concentric with the secondary beam 112, while the rear subcircular section of the elongated hole is concentric with the primary beam 111. The center point of the cross-sectional area is offset relative to the center point of the primary beam 111 and the center point of the secondary beam 112. A third beam can also be arranged so that, for example, the secondary beam is arranged before the primary beam in the feed direction and the third beam is arranged after the primary beam in the feed direction. The individual laser beams are guided without obstructing each other, resulting in exactly one optical channel 3 with exactly one side surface 4, which minimizes heat losses.

[0051] because Figure 5 In the embodiment, the primary beam 111 is arranged without radial offset behind the secondary beam 112 in the feed direction 2. Since the secondary beam 112 is used to preheat the workpiece, it is desirable that the powdered filler material does not interact with the secondary beam 112. This ensures, on the one hand, that the secondary beam 112 can perform only the function of preheating the workpiece, and, on the other hand, that the powdered filler material is heated only by the primary beam 111 and not by the secondary beam 112. This is achieved by the jet nozzle 1 forming a powder unit 7 in the region of the nozzle opening 6 such that the powder unit forms a powder section 11 circumferentially around the light channel 3. A feed section 12, which is free of a powder unit, adjoins the powder section 11 circumferentially. In addition to the powder unit 7, a process gas unit 60 may also be provided, forming a process gas section 61. In this case, the feed section 12 is 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 elongated hole 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 an elongated hole arc, particularly an elongated hole arc in the shape of a horseshoe. Consequently, powder segment 11 extends circumferentially around light channel 3 with respect to its center point, at an angle of less than 360°, particularly between 90° and 330°, and even more particularly between 180° and 300°. This ensures that the powdered filler material flowing from injector 16 inserted into injector guide 19 interacts only with primary jet 111. Consequently, secondary jet 112 can form a treatment zone independent of primary jet 111. When viewed from above, powder segment 11 and feed segment 12 form an elongated hole shape. This also helps reduce or avoid initially identified defects.

[0052] 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 is perpendicular 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 the top view of the proximal region 10.

[0053] Figure 7 The jet nozzle 1 is shown in another perspective view. The nozzle opening 6 has a curved funnel shape. The injector guide 19 is formed within a single curved surface, into which the powder injector 16 can be inserted. The light channel is elongated in the feed direction 2, deviating from a circular shape to achieve the advantages of the present disclosure. The nozzle opening 6 includes a powder unit 7 circumferentially surrounding the light channel 3. This powder unit extends circumferentially around the light channel 3 along a powder section 11 that connects to a powder-free feed section 12.

[0054] Figure 8 The figure shows a perspective cross-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 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 from the jet nozzle 1 in the radial direction. Figure 8 A cross-sectional view of the injector guide 19 is shown. This injector guide 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 (e.g., 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 opening 6. The radially inner cooling chamber 31 is formed at least in the nozzle opening 6. The radially inner cooling chamber can extend from the distal region 8 to the proximal region 10 and is configured as an annular gap segment extending around the light channel 3. In the region of the nozzle opening 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 channel 3 in a cross section extending orthogonally to the longitudinal direction of the jet nozzle 1.

[0055] A transition 32 between the radially inner cooling chamber 31 and the radially outer cooling chamber 33 is provided in the distal region 8. The radially outer cooling chamber 33 has a radial width that decreases in the radial direction in the region of the nozzle opening 6 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 device 19 for guiding the powder jet, which means that there is sufficient installation space for the transition 32.

[0056] The radially outer cooling chamber 33 has a cooling structure for increasing the surface area. The cooling structure can be produced by means of an additive manufacturing method. The cooling structure ensures that the cooling medium contacts as much surface area as possible when returning from the distal region 8 to the proximal region 10, thereby promoting heat dissipation. The cooling structure is optimized to minimize the pressure loss of the cooling medium. This can be achieved by a honeycomb structure 34, such as Figure 8 As shown in .

[0057] Figure 9 The above-mentioned behavior is shown: the powder section 11 with the injector guide device 19 forms a first powder focus 21, which coincides with the center point of the main beam 111. The injectors 16 have a common focus point in the first powder focus 21. In addition, the individual injectors are respectively opposite each other in a mirror-image manner on the diameter at the first powder focus 21. This enables the jet nozzle 1 to efficiently apply the powdered filler material to the workpiece via the main beam 111. In the area of ​​the secondary beam 112, there is a gap 25 in the powder caustic, which is Figure 9 The position of the first powder focus 21 and the position of the gap 25 of the powder caustics can be adjusted by the arrangement of the powder unit 7 and its powder segments 11 and the arrangement of the feed segment 12. The gap 25 of the powder caustics can be substantially half the size of the cross section of the light channel 3 in the distal region 8. This ensures that the secondary beam 112 does not interact with the powdered filler material 120. The wrap angle 26 results from the relationship between the powder segment 11 and the feed segment 12 and their arrangement in the circumferential direction of the light channel 3. ， The powder section extends along the wrap angle around the center point 20 of the light tunnel 3. The wrap angle is between 90° and 330°, in particular between 180° and 300°, with respect to the center point 20 of the light tunnel 3.

[0058] Figure 10The 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 precedes the primary beam 111 in the feed direction 2 and does not interact with the powder caustics, as described with reference to FIG. Figure 5 As described in more detail, when the laser beam interacts with the material surface and the powder jet, a vapor plume can form between the jet nozzle 1 and the workpiece 100. If this vapor plume is not restricted, it may interact in an undesirable manner with at least one laser beam and / or untreated and / or treated material surfaces. Therefore, in the region adjoining the powder section 11, the feed section 12 can be configured as a process gas section 61. This process gas section is formed by a process gas unit 60 arranged radially outside the optical channel 3, which directs process gas onto the workpiece. The process gas section 61 can prevent the spread of undesirable vapor plumes and thus facilitate precise workpiece processing in a robust jet nozzle configuration. The process gas section 61 can form at least one (in this example, three) outlet openings 62. The outlet openings 62 are configured on one end face of the jet nozzle 1. Additional injectors for supplying process gas rather than additional material can be inserted into the corresponding outlet openings 62. The inner diameter of the discharge opening 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 elongated hole 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 jet and the process gas jet.

[0059] Figure 11Another embodiment of a jet nozzle 1 is shown. The nozzle opening 6 has an inclined portion 50, through which a portion of the nozzle opening 6 is cut away. The inclined portion 50 serves to cut away the powder section 11 and the powder-free feed section 12 in the circumferential direction around the light channel 3. The inclined portion 50 reduces the volume of the nozzle opening 6 compared to an embodiment without the inclined portion 50. This ensures that the nozzle opening 6 takes up less installation space. For example, a jet nozzle 1 with the inclined portion 50 can be used to coat brake discs. The brake disc can have a receiving portion that protrudes axially from the functional surface to be coated. The inclined portion 50 ensures that the jet nozzle 1 can be flexibly moved over the functional surface to be coated and can be moved closer to the receiving portion. The inclined portion 50 can be configured to be essentially flat and extend in a plane that is inclined relative to the longitudinal direction of the jet nozzle. The inclined portion 50 represents a boundary surface of the nozzle opening 6, in which the powder unit 7 is not located. In the distal 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.

[0060] Figure 12 A top view shows a jet nozzle 1 having an inclined portion 50. The inclined portion 50 can extend in the distal region 8 in the form of a bypass 51 on the elongated hole. The bypass 51 defines the orientation of the inclined portion 50 on 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 elongated hole. 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 elongated hole and the center point 20 of the light channel 3. The distance between the bypass 51 and the outer edge of the elongated hole is selected so that the wall thickness therebetween ensures sufficient strength and load-bearing capacity of the jet nozzle 1.

[0061] The orientation of the bypass 51, and therefore the orientation of the inclined portion 50 at the nozzle opening 6, can vary depending on the application. For example, the bypass 51 can extend in the feed direction 2. In this case, the bypass 51 extends along the extension of the cross-section of the light channel 3. Therefore, the bypass 51 extends along the long side of the elongated hole. Alternatively, for example, the bypass 51 can extend transversely to the feed direction 2. In this case, the bypass 51 extends transversely to the extension of the cross-section of the light channel 3. Therefore, the bypass 51 extends along a partial circular segment of the elongated hole. Further alternatively, for example, the bypass 51 can extend at an angle relative to the feed direction 2 that is between running along the feed direction 2 and running transversely to the feed direction 2. In this case, the bypass 51 extends along the transition section between the long side of the elongated hole and the partial circular segment of the elongated hole. The direction of the bypass 51 determines the orientation of the inclined portion 50.

[0062] exist Figure 12In the embodiment of FIG, outlet openings 62 are provided at the end of the jet nozzle. The process gas exits the process gas unit 60 through these outlet openings. In this example, the inclined portion 50 is such that the portion of the nozzle opening 6 removed by the inclined portion is completely formed from the powder section 11. As a result, the angle along which the powder section 11 extends is reduced by the inclined portion 50, while the angle along which the process gas unit 60 extends remains essentially the same.

[0063] Where applicable, all individual features presented in the exemplary embodiments may be combined with one another and / or interchanged without departing from the scope of the present invention.

[0064] Reference Signs List

[0065] 1 Jet nozzle 25 Powder caustic gap

[0066] 2 Feed direction 26 Wrap angle

[0067] 3 optical channels 30 cooling system

[0068] 4 Side surface 31 radial inner cooling chamber

[0069] 5 External structure 32 Transition part

[0070] 6 Nozzle port 33 Radial outer cooling chamber

[0071] 7 Powder unit 34 honeycomb structure

[0072] 8 distal region 50 inclined portion

[0073] 9 Flange section 51 Bypass

[0074] 10 Proximal region 60 Processing gas unit

[0075] 11 Powder section 61 Processing gas section

[0076] 12 Feed section 62 Discharge opening

[0077] 13 Coolant inlet

[0078] 14 Coolant outlet 100 Workpiece

[0079] 15 Coupling ring 110 Laser beam

[0080] 16 Powder Injector 111 Main Jet

[0081] 17 entrances take over 112 beams

[0082] 18 outlet pipe 120 powder filling material

[0083] 19 Injector guide device 130 Molten pool

[0084] 20 Center point of optical channel 140 Functional layer

[0085] 21 First Powder Focus

Claims

1. A jet nozzle (1) for laser deposition welding along a feed direction (2), the jet nozzle comprising: - an optical channel (3) for guiding at least one laser beam, said at least one laser beam being directed onto a workpiece; and a powder unit (7) arranged radially outside the light channel (3) for directing at least one powder jet applied to the workpiece; in, The powder unit (7) forms a powder section (11) around the light channel (3) in the circumferential direction at the nozzle opening (6), and a feed section (12) without a powder unit is connected to the powder section in the circumferential direction.

2. The jet nozzle (1) according to claim 1, wherein The feed section (12) is formed in a region of the nozzle opening (6) facing the feed direction (2).

3. The jet nozzle (1) according to any one of the preceding claims, wherein The powder section (11) extends around the light channel (3) along an elongated aperture arc, in particular an elongated aperture arc in the shape of a horseshoe.

4. The jet nozzle (1) according to any one of the preceding claims, wherein The powder segment (11) extends in the circumferential direction around the light channel (3) with respect to a center point (20) of the light channel (3) at an angle of embrace (23), which is between 45° and 330°, in particular between 90° and 300°, and further in particular between 180° and 300°.

5. The jet nozzle (1) according to any one of the preceding claims, wherein The powder section (11) consists 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.

6. The jet nozzle (1) according to claim 5, wherein: The powder section gap is formed in a region of the nozzle opening (6) facing away from the feed direction (2).

7. The jet nozzle (1) according to any one of the preceding claims, wherein The powder section (11) has a plurality of injector guides (19) into which powder injectors (16) can be respectively inserted.

8. The jet nozzle (1) according to claim 7, wherein: The first powder injector is configured to deliver a first powder mass flow, and the second powder injector is configured to deliver a second powder mass flow, wherein the first powder mass flow is different from the second powder mass flow.

9. The jet nozzle (1) according to claim 8, wherein The first powder mass flow conveys a different powder than the second powder mass flow.

10. The jet nozzle (1) according to any one of claims 7 to 9, wherein The first powder injector is configured to form a first powder focus (20), and the second powder injector is configured to form a second powder focus, wherein the first powder focus (20) is different from the second powder focus.

11. The jet nozzle (1) according to any one of the preceding claims, wherein The powder section (11) forms an annular gap section. 12 . The jet nozzle ( 1 ) according to claim 1 , which is produced by means of an additive manufacturing method and consists in particular of copper or a copper alloy, further in particular of a copper-chromium-zirconium alloy.

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

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