Apparatus and method for laser cladding

Abstract

The invention relates to an apparatus (10) for laser cladding having the features of claim 1 and to a method for laser cladding having the features of the additional independent claim.

Description

[0001] 2024P00190WO August 21, 2025

[0002] Title: Device and method for laser cladding

[0003] Description

[0004] The invention relates to a device for laser cladding with features of claim 1 and a method for laser cladding with features of the dependent claim.

[0005] In laser powder deposition welding, a component is exposed to a powder jet, which is then melted and welded onto the component by means of a laser beam. This allows, for example, the creation of a coating on a component. Depending on the material being welded and the selected process parameters, a rough and wavy surface or outgassing in the bonding area may occur.

[0006] A rough adhesive layer can promote bonding defects between the adhesive layer and the wear-resistant layer, as the resulting height differences on the layer surface are less readily wetted by the melt than a smooth layer surface. Furthermore, outgassing between the substrate and the adhesive layer can occur due to high laser beam intensity. With a rough wear-resistant layer, a greater feed rate is required in the subsequent grinding process to meet the requirements for dimensional accuracy and surface finish. The roughness of the adhesive layer can be reduced by adjusting the process parameters during laser powder deposition welding. For example, the fluence of each pass can be increased by reducing the feed rate while maintaining a constant deposition rate. Alternatively, reducing the carrier gas can result in a lower particle velocity and thus a higher particle temperature.Both strategies can lead to a lower melt viscosity, which improves surface wetting. In both cases, roughness is reduced; however, the waviness of the layer increases, as does the risk of irregularities such as outgassing / pores in the layer. Adjusting the carrier gas can also lead to increased soot formation during the process, thus reducing nozzle life.

[0007] It is therefore an object of the present invention to provide a device and a method for laser cladding, whereby the above disadvantages are eliminated.

[0008] The above problem is solved by a device for laser cladding with the features of claim 1. The laser cladding can be high-speed laser powder cladding. Laser cladding can be used, for example, for coating brake discs.

[0009] The device includes a material powder nozzle. The material powder nozzle is configured to generate and focus a material powder jet in a process area. The device also includes a laser device. The laser device is configured to generate a first laser spot and a second laser spot in the process area.

[0010] The device is set up such that the first laser spot and the second laser spot generate a common asymmetric laser intensity profile in the process area.

[0011] This allows for the smoothing of a layer surface, such as an adhesive layer and / or a wear-resistant layer, using simple means. It can improve the bonding between the interlayer and the bond between the adhesive and the wear-resistant layer. Outgassing can be reduced by decreasing the laser intensity in the area of ​​the thermally sensitive substrate. The grinding effort required after laser cladding can be reduced. In some cases, preheating of the process area can be omitted.

[0012] In this context, the process area can refer to an area on the workpiece or component to be processed or coated, in which the material (powder) is melted or welded.

[0013] In this context, a laser spot refers in particular to a laser beam focused on a surface.

[0014] The common asymmetric laser intensity profile can represent a common cross-section through the first laser spot and the second laser spot. In other words, the common asymmetric laser intensity profile can be formed from a cross-section of the first laser spot and a cross-section of the second laser spot, with the cross-sections of the first and second laser spots being oriented collinearly. The common asymmetric laser intensity profile can, in particular, be uninterrupted.

[0015] The laser device can have at least one laser with a wavelength range of 0.8 pm to 2 pm (micrometers) and / or a beam quality (beam parameter product) of 4 mm*mrad to 400 mm*mrad (millimeters*milliradians), preferably 4 mm*mrad to 55 mm*mrad.

[0016] The material powder can be a metal powder. The material powder can be transported or blown into the process area by means of a (carrier) gas jet.

[0017] According to a further development of the device, the laser intensity profile can be asymmetrical along a track offset direction. The track offset direction can be oriented perpendicular to a welded material track and / or point from the process area in a direction where no material powder has yet been applied. The track offset direction can be oriented parallel to a surface of the workpiece to be coated or processed. The track offset direction is specifically oriented in the direction of the track offset.

[0018] This allows for further optimization of the melting of the material powder. According to a further development of the device, the laser intensity profile can be axially symmetric along a track offset direction.

[0019] According to a further development, the second laser spot (and / or its center point) can be arranged trailing the first laser spot (and / or its center point) with respect to a feed direction. The second laser spot (and / or its center point) can be arranged leading the first laser spot (and / or its center point) with respect to the feed direction. The feed direction can be perpendicular to the track offset direction. The feed direction can be oriented parallel to or along the material on the weld track. The feed direction can be oriented parallel to a surface of the workpiece to be coated or machined. The feed direction is, in particular, oriented in the direction of the feed.

[0020] This allows the melting of the material powder to be further optimized.

[0021] According to a further development of the device, the second laser spot can have an intensity that is 1.2 to 3, preferably 1.2 to 1.5, greater than the intensity of the first laser spot.

[0022] This allows the common asymmetric laser intensity profile to be implemented using simple means.

[0023] According to a further development of the device, the intensity of the first laser spot and / or the intensity of the second laser spot can each be adjustable. This allows the common asymmetric laser intensity profile to be implemented as flexibly as possible using simple means.

[0024] According to a further development of the device, the intensity of the first laser spot and / or the intensity of the second laser spot can each have an asymmetric intensity distribution. The intensity distribution along the cross-section of the first laser spot can be asymmetric. The intensity distribution along the cross-section of the second laser spot can be asymmetric.

[0025] This allows the common asymmetric laser intensity profile to be implemented as flexibly as possible using simple means.

[0026] According to a further development of the device, the second laser spot can be arranged outside the material powder beam and / or a focus of the material powder beam.

[0027] This prevents the material powder jet from being negatively affected by the high intensity of the second laser spot, especially from vaporizing the material powder, using simple means.

[0028] Advantageously, the second laser spot can be located at least partially outside the process area, particularly in the opposite direction to the track offset. This allows for a particularly homogeneous transition between adjacent material weld tracks. A previously applied material weld track can be at least partially remelted in an area adjacent to the process area, so that adjacent

[0029] Materials can be joined together on weld marks, especially homogeneously.

[0030] Advantageously, the intensity of the first laser spot can be reduced and the intensity of the second laser spot, which lies at least partially outside the process area, particularly against the direction of the weld offset, can be increased. This allows for precise adjustment of the bond quality between the material on the weld tracks and / or the substrate.

[0031] According to a further development of the device, the second laser spot can be smaller than the first laser spot. The diameter of the second laser spot can be 0.5 to 100% of the diameter of the first laser spot.

[0032] The first laser spot and the second laser spot can have essentially the same size and / or shape.

[0033] This allows for a high intensity to be achieved in a desired area using simple means.

[0034] According to a further development of the device, the first laser spot and the second laser spot can touch only at a single point. Alternatively, the first laser spot and the second laser spot can partially, and in particular completely, overlap (i.e., have more than one point of intersection). The first laser spot and the second laser spot can be arranged at a distance from each other. In particular, there is no distance between the first laser spot and the second laser spot.

[0035] This allows the common asymmetric laser intensity profile to be implemented using simple means.

[0036] According to a further development of the device, the first laser spot and / or the second laser spot can each be formed from several individual laser spots. The first laser spot and / or the second laser spot can each be formed from a laser spot array.

[0037] This allows the first laser spot and / or the second laser spot to be generated using simple means and / or with maximum flexibility.

[0038] According to a further development of the device, the first laser spot and / or the second laser spot can each have a square, rectangular, or hexagonal (geometric) shape. Other geometric shapes for the first and / or the second laser spot are also conceivable.

[0039] According to a further development of the device, the first laser spot and / or the second laser spot can each have an oval shape.

[0040] This allows the first laser spot and / or the second laser spot to be generated using simple means and / or with maximum flexibility. According to a further development of the device, a

[0041] It includes a collimation device and / or a focusing device.

[0042] Preferably, the first and / or second laser spot are formed by a core spot region and a ring spot region that at least partially, and in particular completely, surrounds the core spot region. The core spot region and ring spot region can have different intensities or intensity distributions. Preferably, the core spot region has a lower intensity maximum than the ring spot region. With a first and / or second laser spot designed in this way, the common asymmetric laser intensity profile can be implemented as flexibly as possible. A core spot region with a lower intensity maximum than the ring spot region reliably reduces excessive heat input in the core spot region.

[0043] Advantageously, the first laser spot and / or the second laser spot has a shadowing region. This shadowing region can be created, for example, by means of an aperture that can be positioned in the beam path of the laser beam. The aperture can be essentially opaque to the laser beam, so that the shadowing region has no or a negligible intensity. Alternatively, the aperture can be at least partially transparent to the laser beam, so that the shadowing region has an intensity that is lower than in a region of the first laser spot and / or second laser spot outside the shadowing region. The aperture can have a transmission profile that creates an intensity profile in the shadowing region of the first laser spot and / or second laser spot. The intensity profile is preferably asymmetric, in particular along a track offset direction.

[0044] The aperture can be arranged in the propagation direction of the laser beam, in particular immediately upstream of the collimation device and / or downstream of the focusing device. The aperture can be configured to be moved into the beam path, in particular by pivoting, rotating, and / or adjusting it.

[0045] Alternatively, the device for laser cladding can include a material powder nozzle for generating and focusing a material powder jet in a process area.

[0046] Furthermore, a laser device for generating a first laser spot with a shadowing area in the process area can be included, wherein the device is configured such that the first laser spot and the shadowing area generate a common asymmetric laser intensity profile in the process area. Preferably, the laser intensity profile is asymmetric along a track offset direction.

[0047] Alternatively, the device for laser cladding can include a material powder nozzle for generating and focusing a material powder jet in a process area.

[0048] Furthermore, a laser device for generating a first laser spot can be included, wherein the device is configured such that the first laser spot generates an asymmetric laser intensity profile in the process area. Preferably, the laser intensity profile is asymmetric along a track offset direction. Preferably, the laser cladding device includes a beam shaping device, in particular a diffractive optical element and / or lenses and / or mirrors and / or a prism and / or optical filters and / or lens arrays, wherein the beam shaping device is configured to generate the asymmetric laser intensity profile.

[0049] Preferably, the laser intensity profile is asymmetrical along a track offset direction within the process area.

[0050] Preferably, a first beam splitter, in particular designed as an optical wedge, a dif fractive optical element (DOE), a refractive optical element (ROE), a prismatic beam splitter, or a polarization-based beam splitter, can be arranged in a first dividing plane between the collimation device and the focusing device.

[0051] The first beam splitter can be configured to generate the second laser spot, for example by coupling out a beam component. The device comprising the first beam splitter can further be configured to generate the first laser spot using a beam component not coupled out by the first beam splitter.

[0052] The first beam splitting plane can be located at various positions between the collimating device and the focusing device in the propagation direction. Beam splitting by means of the first beam splitter can occur in an x-direction or in a y-direction perpendicular to the x-direction.

[0053] The laser device comprises at least a first beam source and a second beam source. The first beam source is configured to generate the first laser spot. The second beam source is configured to generate the second laser spot. The first beam source and the second beam source can have substantially the same wavelength, pulse frequency, pulse duration, and / or power. Alternatively, the first beam source and the second beam source can differ from each other in wavelength, pulse frequency, pulse duration, and / or power.

[0054] Preferably, a first beam splitter and a further, in particular a second, beam splitter can be included. The first beam splitter can be configured to generate a beam split in the x-direction in the first splitting plane. The further, in particular second, beam splitter can be arranged in a second splitting plane that lies behind the first splitting plane in the propagation direction. The further, in particular second, beam splitter can be configured to generate a beam split in the y-direction. By means of the first beam splitter in the first splitting plane and the second beam splitter in the second splitting plane, a first spot pair, consisting of the first laser spot and the second laser spot, and a second spot pair, consisting of another first laser spot and another second laser spot, can be generated. The first spot pair and the second spot pair can at least partially overlap or superimpose.

[0055] Preferably, the asymmetric intensity profile increases against the direction of the track offset, starting from an initial intensity, in particular 0% of the maximum intensity, to a final intensity, in particular 100% of the maximum intensity. The progression from the initial intensity to the final intensity can be linear, progressive, degressive, or stepwise.

[0056] The above problem is further solved by a laser cladding process with the features of the dependent claim. The laser cladding can be high-speed laser powder cladding. Laser cladding can be used, for example, for coating brake discs. The process comprises the following steps:

[0057] Generating and focusing a material powder jet in a process area.

[0058] Generating an initial laser spot in the process area.

[0059] Generating a second laser spot in the process area.

[0060] Generating a common asymmetric laser intensity profile using the first laser spot and the second laser spot.

[0061] The laser cladding process can alternatively comprise the following steps: Generating and focusing a material powder beam in a process area. Generating a first laser spot with a shadowing area in the process area. Generating a common asymmetric laser intensity profile in the process area using the first laser spot and the shadowing area.

[0062] The laser cladding process can alternatively comprise the following steps: Generating and focusing a material powder beam in a process area. Generating an initial laser spot with an asymmetric laser intensity profile in the process area.

[0063] Preferably, the asymmetric laser intensity profile is generated by means of a beam shaping device, in particular a diffractive optical element and / or lenses and / or mirrors and / or a prism and / or optical filters and / or lens arrays.

[0064] This allows for the smoothing of a layer surface, such as an adhesive layer and / or a wear-resistant layer, using simple means. It can improve the bonding between the interlayer and the bond between the adhesive and the wear-resistant layer. Outgassing can be reduced by decreasing the laser intensity in the area of ​​the thermally sensitive substrate. The grinding effort required after laser cladding can be reduced. In some cases, preheating of the process area can be omitted.

[0065] In this context, the process area can refer to an area on the workpiece or component to be processed or coated, in which the material (powder) is melted or welded.

[0066] In this context, a laser spot refers in particular to a laser beam focused on a surface.

[0067] The common asymmetric laser intensity profile can represent a common cross-section through the first laser spot and the second laser spot. In other words, the common asymmetric laser intensity profile can be formed from a cross-section of the first laser spot and a cross-section of the second laser spot, with the cross-sections of the first and second laser spots being oriented collinearly. The laser intensity profile can be uninterrupted.

[0068] According to a further development of the procedure, the procedure can include the following step:

[0069] Setting the intensity and / or intensity distribution of the first laser spot and / or the second laser spot.

[0070] This allows the common asymmetric laser intensity profile to be implemented as flexibly as possible using simple means.

[0071] According to a further development of the method, a device as described above can be used to carry out the method.

[0072] Regarding the advantages achievable with this method, reference is made to the relevant explanations concerning the device. The measures described in connection with the device and / or those explained below can be used to further develop the method.

[0073] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments based on the

[0074] Drawings. They each show schematically:

[0075] Fig. 1 shows a device for laser cladding welding,

[0076] Fig. 2 shows different embodiments of a first laser spot and a second laser spot of the device according to Figure 1.

[0077] Fig. 3 shows different embodiments of a common asymmetric laser intensity profile of the device according to Figure 1.

[0078] Fig. 4 shows different embodiments of a laser device of the apparatus according to Figure 1.

[0079] Fig. 5 shows further different embodiments of a first laser spot and a second laser spot of the device according to Figure 1.

[0080] Fig. 6 shows further different embodiments of a first laser spot and a second laser spot of the device according to Figure 1.

[0081] Fig. 7 shows further different embodiments of a first laser spot and a second laser spot of the device according to Figure 1.

[0082] Fig. 8 shows further embodiments of a laser device of the apparatus according to Fig. 1. In the following description and in the figures, corresponding components and elements bear the same reference numerals. For the sake of clarity, not all reference numerals are shown in all figures.

[0083] Figure 1 schematically shows a device 10 for laser cladding.

[0084] The device 10 comprises a material powder nozzle 12. The material powder nozzle 12 is configured to generate and focus a material powder jet 14 in a process area 16. The process area 16 can be arranged on a workpiece 11 or its surface.

[0085] The device 10 comprises a laser unit 18. The laser unit 18 is configured to generate a first laser spot 20 and a second laser spot 22 in the process area 16. The device 10 is configured such that the first laser spot 20 and the second laser spot 22 generate a common asymmetric laser intensity profile 24 (see Figure 3) in the process area 16.

[0086] The first laser spot 20 can have a diameter of 1 mm to 20 mm (millimeters), in particular from 3.2 mm to 4.0 mm. The second laser spot 22 can have a diameter of 200 pm to 10 mm, in particular from 1 mm or less.

[0087] The laser intensity profile 24 can be asymmetrical along a track offset direction 26. The laser intensity profile 24 can exhibit a decreasing intensity along the track offset direction 26. In Figure 1, the track offset direction 26 is oriented to the left. The track offset direction 26 points from the individual (material) tracks 25, each formed by melted or welded material powder (material powder application), in a direction where no material powder has yet been melted or welded. In this case, the track offset direction 26 is oriented parallel to the surface of the workpiece 11.

[0088] Figure 2 schematically shows different embodiments of the first laser spot 20 and the second laser spot 22 of the device 10 according to Figure 1.

[0089] Figure 2 above shows four exemplary embodiments. It depicts the first laser spot 20 and four second laser spots 22, each arranged in a different position. The combination of the first laser spot 20 and one of the four second laser spots 22 represents one of the four exemplary embodiments. In this case, the first laser spot 20 and the four second laser spots 22 each have a round shape. The first laser spot 20 and the four second laser spots 22 are circular in shape.

[0090] The process area 16 is represented by two dashed lines that mark the boundaries of the process area 16 with respect to the track offset direction 26. The tracks 25 run particularly in the area of ​​the upper dashed line and, in this case, have a course corresponding to the upper dashed line. A feed direction 28 is shown, which in this case is oriented perpendicular to the track offset direction 26. It is also conceivable that the feed direction 28 could be oriented not perpendicular (but at an angle other than 90°) to the track offset direction 26. The feed direction 28 defines, in particular, the direction in which the first laser spot 20, the second laser spot 22, and / or the material powder jet 14 are moved. In this case, the feed direction 28 is oriented parallel to the surface of the workpiece 11 (see Figure 1).

[0091] The second laser spot 22 can be arranged trailing or leading the first laser spot 20 with respect to the feed direction 28. In the present case, in a first of the four embodiments shown above in Figure 2, the second laser spot 22, shown on the right in Figure 2, is arranged leading the first laser spot 20. In a second embodiment of the four embodiments shown above in Figure 2, the second laser spot 22, shown on the left in Figure 2, is arranged trailing the first laser spot 20.

[0092] The first laser spot 20 and the second laser spot 22 can touch at only one point (i.e., have a single common intersection point) or overlap partially, and in particular completely. In the present case, in a third of the four embodiments shown above in Figure 2, the second laser spot 22, which is arranged centrally and outside the first laser spot 20 in Figure 2, and the first laser spot 20 touch at one point. It is also conceivable that the first laser spot 20 and the second laser spot 22 are arranged in such a way that the two laser spots 20, 22 partially overlap (i.e., have more than one intersection point).In a fourth of the four exemplary embodiments shown in Figure 2 above, the second laser spot 22, which is arranged centrally and within the first laser spot 20 in Figure 2, and the first laser spot 20 completely overlap (the second laser spot 22 is arranged completely within the first laser spot 20).

[0093] The second laser spot 22 can be smaller than the first laser spot 20.

[0094] The second laser spot 22 can be arranged outside the material powder beam 14 and / or a focus of the material powder beam 14.

[0095] Figure 2 (center) shows four further embodiments. The four embodiments shown in the center of Figure 2 differ from the four embodiments shown in the top of Figure 2 in the following ways:

[0096] The first laser spot 20 is not round or circular, but has a hexagonal shape. Alternatively or additionally, it is conceivable that the second laser spot 22 could also have a hexagonal shape. The first laser spot 20 and / or the second laser spot 22 could also have a square (or other geometric) shape.

[0097] Figure 2 below shows four further embodiments. The four embodiments shown below in Figure 2 differ from the four embodiments shown in the middle of Figure 2 in the following way: The first laser spot 20 is formed from several individual laser spots 21. In this case, the first laser spot 20 is formed by seven individual laser spots 21 and is marked by a dashed line. The first laser spot 20 thus has a (essentially) hexagonal shape. For the sake of clarity, the embodiment in which the second laser spot 22 is arranged within the first laser spot 20 is not shown below in Figure 2. Alternatively or additionally, it is conceivable that the second laser spot 22 could be formed from several individual laser spots.

[0098] Figure 3 schematically shows different embodiments of the common asymmetric laser intensity profile 24 of the device 10 according to Figure 1. Four embodiments are shown, with the first laser spot 20, the second laser spot 22, the track offset direction 26, and the feed direction 28 shown on the left in Figure 3, and the corresponding laser intensity profile 24 shown on the right in Figure 3. The first and second laser spots 20 and 22 are each circular in shape.

[0099] The laser intensity profile 24 represents an intensity distribution of the two laser spots 20, 22 along the track offset direction 26. In each laser intensity profile 24, the laser intensity (y-axis) is plotted over a distance (x-axis) along the track offset direction 26 in arbitrary units. Each laser intensity profile 24 is composed of an intensity 27 of the first laser spot 20 and an intensity 29 of the second laser spot 22. In the uppermost embodiment shown in Figure 3, the second laser spot 22 is (completely) located within the first laser spot 20, with the second laser spot 22 positioned at the outer edge of the first laser spot 20. The intensity of the first laser spot 20 and the second laser spot 22 are each constant. The intensity of the second laser spot 22 is greater than the intensity of the first laser spot 20.

[0100] The intensity 29 of the second laser spot 22 can be greater by a factor of 1.2 to 1.5 than the intensity 27 of the first laser spot 20.

[0101] The intensity 27 of the first laser spot 20 and / or the intensity 29 of the second laser spot 22 can each be adjustable.

[0102] The intensity 27 of the first laser spot 20 and / or the intensity 29 of the second laser spot 22 can each exhibit an asymmetric intensity distribution. The asymmetric intensity distribution can be implemented or adjusted, for example, by means of a diffuser.

[0103] The second-highest embodiment shown in Figure 3 differs from the topmost embodiment shown in Figure 3 in the following ways:

[0104] The first laser spot 20 has an asymmetric intensity distribution. The intensity 27 of the first laser spot 20 increases in the opposite direction to the track offset 26. In other words, the intensity 27 of the first laser spot 20 decreases along the track offset direction 26. The second-lowest embodiment in Figure 3 differs from the topmost embodiment in Figure 3 in the following ways:

[0105] The second laser spot 22 is arranged outside the first laser spot 20. The two laser spots 20, 22 only touch at one point (have a single common intersection point). Accordingly, the laser intensity profile 24 of the second-lowest embodiment in Figure 3 extends over a longer distance than the laser intensity profile 24 of the topmost embodiment in Figure 3 (see the respective x-axis).

[0106] The lowest embodiment shown in Figure 3 differs from the second-highest embodiment shown in Figure 3 in the following ways:

[0107] The second laser spot 22 is arranged centrally or coaxially within the first laser spot 20.

[0108] Figure 4 schematically shows different embodiments of the laser device 18 of the device 10 according to Figure 1.

[0109] In the uppermost embodiment of Figure 4, the first laser spot 20 is generated by means of a first fiber 31 and the second laser spot 22 by means of a second fiber 33. To generate the laser spots 20 and 22, a collimation device 35 and a focusing device 37 are arranged downstream of the fibers 31 and 33. The first fiber 31 and the second fiber 33 can be of different sizes and combined in a coupling connector. The diameter of the first fiber 31 can be greater than 1000 pm. The diameter of the second fiber 33 can be a maximum of 500 pm. The two fibers 31 and 33 can be arranged parallel to each other. The first and second fibers 31 and 33 can be fed by a common laser. The laser device 18 shown is suitable, for example, for generating the laser spots 20 and 22 shown in Figure 2 above.

[0110] The second-highest embodiment shown in Figure 4 differs from the topmost embodiment shown in Figure 4 in the following ways:

[0111] The two fibers 31 and 33 are each fed by a separate laser. The first fiber 31 can be fed by an infrared laser. The second fiber 33 can be fed by a green laser. The diameter of the first fiber 31 can be greater than 1000 pm. The diameter of the second fiber 33 can be less than 1000 pm. The two fibers 31 and 33 can be oriented perpendicular to each other. A collimation device 35 can be arranged after the first and second fibers 31 and 33, respectively. A beam splitter 39 can be arranged between the collimation devices 35 and the focusing device 37.

[0112] The second-lowest embodiment shown in Figure 4 differs from the uppermost embodiment in the following ways:

[0113] In the present case, both laser spots 20, 22 are controlled by means of the first

[0114] Fiber 31 is generated (the second fiber 33 is not present or is not required). After the first fiber 31 is the collimation device 35 and the

[0115] Focusing device 37 arranged. Between the

[0116] A wedge surface 41 and a lens array 43 are arranged between the collimation device 35 and the focusing device 37. The first laser spot 20 can be generated by means of the lens array 43, and the second laser spot 22 by means of the wedge surface 41. The lens array 43 can be designed to be adjustable, following the bifocal principle. The illustrated laser device 18 is suitable, for example, for generating the laser spots 20 and 22 shown in the center of Figure 2.

[0117] It is also conceivable that the lens array 43 can be configured as a diffractive optical element (DOE). Using the DOE, several individual laser spots 21 can be generated, for example, to produce the first laser spot 20. In this way, for example, the laser spots 20 and 22 shown below in Figure 3 can be generated.

[0118] The lowest embodiment shown in Figure 4 differs from the second lowest embodiment in the following ways:

[0119] Instead of the lens array 43 with a wedge surface 41, a diffractive optical element (DOE) 45 and a planar surface 47 are provided here. The illustrated laser device 18 is suitable for generating, for example, the laser spots 20, 22 shown in the bottommost embodiment of Figure 3.

[0120] The following describes a laser cladding process with reference to Figures 1 to 4. The process comprises the following steps:

[0121] Generating and focusing a material powder jet 14 in a process area 16. Generating a first laser spot 20 in the process area 16.

[0122] Generating a second laser spot 22 in the process area 16 .

[0123] Generating a common asymmetric laser intensity profile 24 using the first laser spot 20 and the second laser spot 22 .

[0124] The procedure may include the following step:

[0125] Setting the intensity of the first laser spot 20 and / or the second laser spot 22. Alternatively or additionally, an intensity distribution of the first laser spot 20 and / or the second laser spot 22 can be set.

[0126] To carry out the method, a device 10 as described above can be used. The device 10 can be the one shown in Figures 1 to 4.

[0127] Figure 5 Above and Figure 5 Below schematically show further different embodiments of the first laser spot 20 and the second laser spot 22 of the device 10 according to Figure 1.

[0128] The first laser spot 20 and the second laser spot 22 each have a round shape. The first laser spot 20 and the second laser spot 22 are circular and have the same diameter. The first laser spot 20 and the second laser spot 22 are at least partially superimposed. In other words, the first laser spot 20 and the second laser spot 22 overlap.

[0129] The feed direction 28 is as shown in Fig. 2 and is oriented perpendicular to the track offset direction 26. It is also conceivable that the feed direction 28 may not be oriented perpendicular (but at an angle other than 90°) to the track offset direction 26. The feed direction 28 defines, in particular, the direction in which the first laser spot 20, the second laser spot 22, and / or the material powder jet 14 are moved. In this case, the feed direction 28 is oriented parallel to the surface of the workpiece 11 (see Fig. 1).

[0130] The second laser spot 22 can be arranged outside the material powder beam 14 and / or a focus of the material powder beam 14.

[0131] The second laser spot 22 can be located outside the process area 16, in particular against the track offset direction 26.

[0132] Figure 5 (middle) differs from Figure 5 (top) in that the first laser spot 20 has a shadowing area 51. The shadowing area 51 is created by means of an aperture (not shown) that can be positioned in the beam path of the laser beam. The aperture (not shown) has a transmission profile that, in the shadowing area 51 of the first laser spot 20, produces an intensity profile that decreases linearly in the direction of the track offset 26. The common asymmetric intensity profile of the first laser spot 21 and the second laser spot 22 is asymmetric along the direction of the track offset 26.

[0133] Figure 5 (bottom) differs from Figure 5 (top) in that the first laser spot 20 has a core spot region 53 and a ring spot region 59, and the second laser spot 22 has a core spot region 55 and a ring spot region 57. The ring spot region 59 at least partially surrounds the core spot region 53, and in this case, completely. Likewise, the ring spot region 57 at least partially surrounds the core spot region 55, and in particular, completely. The core spot region 53 and the core spot region 55 overlap at least partially. The intensity or intensity distribution of the core spot region 53, 55 can differ from the intensity or intensity distribution of the ring spot region 59, 57. In particular, an intensity maximum of the core spot region 53, 55 can be smaller than an intensity maximum of the ring spot region 59, 57.

[0134] Figure 6 schematically shows further different embodiments of the first laser spot 20 and the second laser spot 22 of the device 10 according to Figure 1. The first laser spot 20 and the second laser spot 22 each have an oval shape. In Figure 6 (top), the first laser spot 20 and the second laser spot 22 are at least partially superimposed. In other words, the first laser spot 20 and the second laser spot 22 overlap. Figure 6 (bottom) differs from Figure 6 (top) in that the first laser spot 20 and the second laser spot 22 are arranged without any distance between them. In particular, there is no distance between the first laser spot 20 and the second laser spot 22. Figure 7 schematically shows further different embodiments of the first laser spot 20 and the second laser spot 22 of the device 10 according to Figure 1. The embodiments of the Fig.Figure 7 differs from the embodiments shown in Figure 6 only in the shape of the first laser spot 20 and the second laser spot 22. In the present case, the first laser spot 20 and the second laser spot 22 have a rectangular shape.

[0135] Figure 8 shows further embodiments of a laser device 18 of the apparatus 10 according to Figure 1. In Figure 8, the first laser spot 20 and the second laser spot 22 are generated by means of a first fiber 31. To generate the laser spots 20 and 22, a collimation device 35 and a focusing device 37 are arranged downstream of the first fiber 31. The diameter of the first fiber 31 can be greater than 1000 pm. The laser device 18 shown is suitable, for example, for generating the laser spots 20 and 22 shown in Figures 2, 5, 6, and 7. A first beam splitter 61, in particular designed as an optical wedge, is arranged in a first dividing plane 65 between the collimation device 35 and the focusing device 37.

[0136] The second laser spot 22 can be generated by coupling out a beam component using the first beam splitter 61. The first laser spot 20 can be generated using a beam component not coupled out by the first beam splitter 61.

[0137] Figure 8 Middle differs from Figure 8 Top in that the first division plane 65 is located at different positions in the propagation direction between the collimation device 35 and the focusing device 37. Furthermore, in Figure 8 Top, the first

[0138] The beam splitter 65 produces a beam split in the x-direction, while in Fig. 8 Middle, a beam split is produced in the y-direction, perpendicular to the x-direction. Fig. 8 Bottom represents a combination of Fig. 8 Top and Middle. By means of the first beam splitter 61, a beam split occurs in the x-direction in a first splitting plane 65. A second beam splitter 63 is arranged in a second splitting plane 67, which lies behind the first splitting plane 65 in the propagation direction. By means of the second beam splitter 63, a beam split occurs in the y-direction. By means of the first beam splitter 61 in the first division plane 65 and the second beam splitter 63 in the second division plane 67, a first spot pair consisting of the first laser spot 20 and the second laser spot 22 and a second spot pair consisting of another first laser spot 20 and another second laser spot 22 are generated.The first spot pair and the second spot pair overlap, or at least partially overlap.

Claims

Patent claims 1. Device (10) for laser cladding comprising: a material powder nozzle (12) for generating and focusing a material powder jet (14) in a process area (16), a laser device (18) for generating a first laser spot (20) and a second laser spot (22) in the process area (16), wherein the device (10) is configured such that the first laser spot (20) and the second laser spot (22) generate a common asymmetric laser intensity profile (24) in the process area (16).

2. Device (10) according to claim 1, characterized in that the laser intensity profile (24) is asymmetrically designed along a track offset direction (26).

3. Device (10) according to claim 1 or 2, characterized in that the second laser spot (22) is arranged trailing or leading the first laser spot (20) with respect to a feed direction (28).

4. Device (10) according to one of the preceding claims, characterized in that an intensity (29) of the second laser spot (22) is greater by a factor of 1.2 to 3, preferably 1.2 to 1.5, than an intensity (27) of the first laser spot (20) .

5. Device (10) according to the preceding claim, characterized in that the intensity (27) of the The intensity of the first laser spot (20) and / or the intensity (29) of the second laser spot (22) can each be adjusted.

6. Device (10) according to one of the two preceding claims, characterized in that the intensity (27) of the first laser spot (20) and / or the intensity (29) of the second laser spot (22) each exhibit an asymmetric intensity distribution.

7. Device (10) according to one of the preceding claims, characterized in that the second laser spot (22) is arranged outside the material powder jet (14) and / or a focus of the material powder jet (14).

8. Device (10) according to one of the preceding claims, characterized in that the second laser spot (22) is smaller than the first laser spot (20) .

9. Device (10) according to one of the preceding claims, characterized in that the first laser spot (20) and the second laser spot (22) touch exclusively at one point or partially, in particular completely, overlap.

10. Device (10) according to one of the preceding claims, characterized in that the first laser spot (20) and / or the second laser spot (22) are each formed from several individual laser spots (21).

11. Device (10) according to one of the preceding claims, characterized in that the first laser spot (20) and / or the second laser spot (22) each have a square, rectangular or hexagonal shape.

12. Laser cladding process comprising the following steps: Generating and focusing a material powder jet (14) in a process area (16) ; Generating a first laser spot (20) in the process area (16) ; Generating a second laser spot (22) in the process area (16) ; Generating a common asymmetric laser intensity profile (24) using the first laser spot (20) and the second laser spot (22) .

13. Method according to claim 12, characterized by the step: Setting an intensity and / or an intensity distribution of the first laser spot (20) and / or the second laser spot (22) .

14. Method according to claim 12 or 13, characterized in that a device (10) according to one of claims 1 to 11 is used to carry out the method.

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