Apparatus and method for laser cladding

Abstract

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

Description

[0001] Title: Device and method for laser cladding

[0002] Description

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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 unit. The laser unit is configured to generate at least one laser beam along a laser beam axis. The laser unit is also configured to focus the laser beam in the process area.

[0009] The device is set up such that the material powder jet has a powder density profile in the process area that is asymmetrical to the laser beam axis.

[0010] This allows for the smoothing of a layer surface, whether an adhesive layer 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. It can reduce outgassing by shading sensitive substrate areas. It can reduce the grinding effort required after laser cladding. A thinner wear-resistant layer is possible because the smoother layer surface necessitates less grinding allowance.

[0011] 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.

[0012] In this context, a laser beam axis refers specifically to an optical axis of the device that runs between the material powder nozzle and the workpiece to be processed. The laser device can comprise at least one laser with a wavelength range of 0.8 pm to 2 gm (micrometers) and / or a beam quality (beam parameter product) of 4 mm*mrad to 400 mm*mrad (millimeters*mrad), preferably 4 mm*mrad to 55 mm*mrad. The laser device can be configured to generate a laser beam focus diameter of 1 mm to 20 mm (millimeters). The laser device can be configured to generate a tophat, a concave, or annular intensity profile of the laser beam in the process area and / or at the laser beam focus. The laser device can employ a bifocal technique for generating the laser beam.

[0013] 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.

[0014] According to a further development of the device, the powder density profile is asymmetrical to the laser beam axis 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.

[0015] This allows for further optimization of the melting of the material powder. 2024P00179WG 5 27 . 10 . 2025

[0016] According to a further development of the device, the

[0017] The material powder jet, whose focus and / or the material powder nozzle is arranged (at least partially) ahead of the laser beam axis with respect to the track offset direction.

[0018] This allows the melting of the material powder to be further optimized.

[0019] Due to the higher material powder density (or powder jet intensity) in front of the laser beam axis, the thermally sensitive substrate can be protected from the laser beam by shading. Due to the lower material powder density (or powder jet intensity) behind the laser beam axis, the laser intensity can be locally increased and the already applied part of the layer smoothed.

[0020] According to a further development of the device, the device can be configured such that the material powder jet is displaceable or movable relative to the laser beam axis (and / or to the laser beam). In particular, a focus of the material powder jet can be displaceable or movable relative to the laser beam axis (and / or to the laser beam). It is also conceivable that the material powder nozzle can be displaceable or movable relative to the laser beam axis (and / or to the laser beam). The material powder jet, its focus, and / or the material powder nozzle can each be displaceable or movable along the track offset direction. 2024P00179WG 6 27.10.2025

[0021] This allows the asymmetrical powder density profile to be implemented as flexibly as possible using simple means.

[0022] According to a further development of the device, the device can be configured such that the powder density profile has a shape that deviates from the Gaussian shape (Gaussian distribution or normal distribution). In particular, the powder density profile is not Gaussian.

[0023] This allows the melting of the material powder to be further optimized.

[0024] According to a further development of the device, the material powder nozzle can be designed as an azimuthal nozzle. Other nozzle types are also conceivable.

[0025] This allows the asymmetrical powder density profile to be implemented using simple means. In particular, the material powder nozzle, designed as an azimuthal nozzle, can be conveniently adjusted to the center of the laser beam axis.

[0026] According to a further development of the device, the material powder nozzle can comprise several injectors. The injectors can each be configured to generate an individual powder jet. The individual powder jets can form the material powder jet (e.g., by superimposition). The device can be configured such that the powder quantity of at least one individual powder jet, and in particular of all individual powder jets, is adjustable. It is conceivable that each injector or individual powder jet can be configured to be separately (individually) adjustable. This allows the asymmetrical powder density profile to be implemented with simple means and with maximum flexibility.

[0027] According to further training, the arrangement and / or orientation of at least one injector, and in particular all injectors, can be adjustable. It is conceivable that the injectors can each be individually adjustable in their arrangement and / or orientation. In particular, the angle of incidence or impact of the individual powder jets can be set as desired by adjusting the orientation of the respective injectors. By varying the arrangement of the injectors, for example, the powder density and / or the maximum powder density (focus of the material powder jet) can be set as desired. For example, two injectors arranged side by side can produce a (locally) higher powder density than a single injector.

[0028] This allows the asymmetrical powder density profile to be implemented with simple means and as flexibly as possible.

[0029] 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:

[0030] Generating and focusing a material powder jet in a process area. Generating at least one laser beam along a laser beam axis and focusing the laser beam in the process area.

[0031] Generating a powder density profile of the material powder jet in the process area that is asymmetrical to the laser beam axis.

[0032] This allows for the smoothing of a layer surface, whether an adhesive layer 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. It can reduce outgassing by shading sensitive substrate areas. It can reduce the grinding effort required after laser cladding. A thinner wear-resistant layer is possible because the smoother layer surface necessitates less grinding allowance.

[0033] 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.

[0034] In this context, a laser beam axis refers specifically to an optical axis of the device that runs between the material powder nozzle and the workpiece to be processed. According to a further development of the method, the method can comprise the following step:

[0035] Generating the powder density profile by shifting the material powder jet, its focus and / or the material powder nozzle along, in particular in, a track offset direction.

[0036] This allows the powder density profile to be implemented using simple means.

[0037] According to a further development of the procedure, the process can include the following steps:

[0038] Generating the material powder jet using multiple individual powder jets.

[0039] Setting the powder quantity for at least one individual powder jet, in particular for all individual powder jets. This setting can be implemented separately (individually) for each individual powder jet, for example, in the case of multiple individual powder jets.

[0040] This allows the powder density profile to be implemented as flexibly as possible using simple means.

[0041] According to a further development of the procedure, the procedure can include the following step:

[0042] Setting the arrangement and / or orientation of at least one individual powder jet, in particular all individual powder jets. This setting can be implemented separately (individually) for each individual powder jet, for example.

[0043] This allows the powder density profile to be implemented as flexibly as possible using simple means.

[0044] According to a further development of the method, a device as described above can be used to carry out the method.

[0045] 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.

[0046] 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 with reference to the drawings. The drawings show, schematically:

[0047] Fig. 1 shows a device for laser cladding welding,

[0048] Fig. 2 shows an asymmetrical powder density profile of a material powder jet of the device according to Figure 1 according to a first embodiment and

[0049] Fig. 3 shows the asymmetrical powder density profile of the material powder jet of the device according to Figure 1, according to a second embodiment. 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.

[0050] Figure 1 schematically shows a device 10 for laser cladding.

[0051] 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.

[0052] The device 10 comprises a laser unit 18. The laser unit 18 is configured to generate at least one laser beam 20 along a laser beam axis 22 and to focus the laser beam 20 in the process area 16. The device 10 is configured such that the material powder jet 14 has a powder density profile 24 (see Figures 2 and / or 3) in the process area 16 that is asymmetrical with respect to the laser beam axis 22.

[0053] The laser beam axis 22 refers to the optical axis of the laser device 18, which extends in particular between the material powder nozzle 12 and the workpiece 11.

[0054] The powder density profile 24 can be asymmetrical to the laser beam axis 22 along a track offset direction 26. The powder density profile 24 can have a maximum 27 shifted in the track offset direction 26 (see Figures 2 and / or 3). In Figure 1, the track offset direction

[0055] 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. The track offset direction 26 is oriented parallel to the surface of the workpiece 11.

[0056] The material powder jet 14, its focus and / or the material powder nozzle 12 can be arranged leading to the laser beam axis 22 with respect to the track offset direction 26.

[0057] The device 10 can be configured such that the material powder jet 14, its focus and / or the material powder nozzle 12 are displaceable relative to the laser beam axis 22. The material powder jet 14, its focus and / or the material powder nozzle 12 can be displaceable along the track offset direction 26.

[0058] The material powder nozzle 12 can be designed as an azimuthal nozzle. It is also conceivable that the material powder nozzle 12 can be designed as a conventional nozzle.

[0059] The material powder nozzle 12 can comprise several injectors for generating individual powder jets (not shown). The individual powder jets can then form the material powder jet 14. The device 10 can be configured such that a quantity of powder of at least one

[0060] The individual powder jet, in particular all individual powder jets, is adjustable. It is conceivable that the individual powder jets can be adjusted separately or individually.

[0061] The arrangement and / or orientation of at least one injector, in particular all injectors, can be adjustable. It is conceivable that the individual injectors can be separately or individually adjustable.

[0062] Figure 2 schematically shows the asymmetrical powder density profile 24 of the material powder jet 14 of the device 10 according to Figure 1 according to a first embodiment.

[0063] The powder density (Y-axis) of the material powder jet 14 is depicted over a path length (X-axis) in arbitrary units. In this case, the X-axis of the powder density profile 24 extends along or opposite the track offset direction 26. Thus, the powder density profile 24 represents a cross-section of the material powder jet 14, particularly in the process area 16, along the track offset direction 26.

[0064] In this case, the powder density profile 24 is Gaussian. The maximum 27 of the powder density profile 24 is shifted (leading) relative to the laser beam axis 22 (see Figure 1) in the track offset direction 26. The maximum 27 is formed in particular by the focus of the material powder jet 14. Thus, the focus of the material powder jet 14 is arranged leading to the laser beam axis 22 with respect to the track offset direction 26. Figure 3 schematically shows the asymmetrical powder density profile 24 of the material powder jet 14 of the device 10 according to Figure 1 according to a second embodiment. The second embodiment differs from the first embodiment shown in Figure 2 in the following ways:

[0065] The powder density profile 24 has a shape that differs from the Gaussian shape.

[0066] The following describes a method for laser surface welding using Figures 1 to 3.

[0067] The procedure includes the following steps:

[0068] Generating and focusing a material powder jet 14 in a process area 16 .

[0069] Generating at least one laser beam 20 along a laser beam axis 22 and focusing the laser beam 20 in the process area 16 .

[0070] Generating a powder density profile 24 of the material powder jet 14 in the process area 16 that is asymmetric to the laser beam axis 22.

[0071] The procedure may include the following step:

[0072] Generating the powder density profile 24 by displacing the material powder jet 14, its focus and / or the material powder nozzle 12 along, in particular in, a track offset direction 26. The method may comprise the following steps:

[0073] Generating the material powder jet 14 using several individual powder jets .

[0074] Setting the powder quantity for at least one individual powder jet, and especially for all individual powder jets. This can be implemented individually for each individual powder jet, for example, when there are multiple individual powder jets.

[0075] The procedure may include the following step:

[0076] Setting the arrangement and / or orientation of at least one individual powder jet, in particular all individual powder jets. This can, for example, be implemented separately for each individual powder jet when dealing with multiple individual powder jets.

[0077] 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 3.

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 at least one laser beam (20) along a laser beam axis (22) and focusing the laser beam (20) in the process area (16), wherein the device (10) is configured such that the material powder jet (14) has a powder density profile (24) in the process area (16) that is asymmetric with respect to the laser beam axis (22).

2. Device (10) according to claim 1, characterized in that the powder density profile (24) is formed asymmetrically to the laser beam axis (22) along a track offset direction (26).

3. Device (10) according to claim 2, characterized in that the material powder jet (14), its focus and / or the material powder nozzle (12) is arranged leading to the laser beam axis (22) with respect to the track offset direction (26).

4. Device (10) according to one of the preceding claims, characterized in that the device (10) is arranged such that the material powder jet (14), its focus and / or the material powder nozzle (12) is relative to the laser beam axis (22) , in particular along the track offset direction (26) , are each designed to be displaceable.

5. Device (10) according to one of the preceding claims, characterized in that the device (10) is arranged such that the powder density profile (24) has a shape different from the Gaussian shape.

6. Device (10) according to one of the preceding claims, characterized in that the material powder nozzle (12) is designed as an azimuthal nozzle.

7. Device (10) according to one of the preceding claims, characterized in that the material powder nozzle (12) comprises several injectors for generating individual powder jets, wherein the individual powder jets form the material powder jet (14), wherein the device (10) is configured such that a powder quantity of at least one individual powder jet, in particular of all individual powder jets, is adjustable.

8. Device (10) according to the preceding claim, characterized in that an arrangement and / or an orientation of at least one injector, in particular of all injectors, is adjustable.

9. The laser cladding process comprises the following steps: Generating and focusing a material powder jet (14) in a process area (16) ; Generating at least one laser beam (20) along a laser beam axis (22) and focusing the laser beam (20) in the process area (16) ; Generating a powder density profile (24) of the material powder jet (14) in the process area (16) that is asymmetric with respect to the laser beam axis (22).

10. Method according to claim 9, characterized by the step: Generating the powder density profile (24) by moving the material powder jet (14), its focus and / or the material powder nozzle (12) along, in particular in, a track offset direction (26) .

11. Method according to claim 9 or 10, characterized by the steps: Generating the material powder jet (14) by means of several individual powder jets; Setting a powder quantity for at least one individual powder jet, in particular for all individual powder jets.

12. Method according to claim 11, characterized by the step: Setting an arrangement and / or orientation of at least one single powder jet, in particular all single powder jets.

13. Method according to one of claims 9 to 12, characterized in that a device (10) according to one of claims 1 to 8 is used to carry out the method.

Images