Laser deposition welding method for producing coating layers on opposing surfaces of a component

Abstract

The invention relates to a laser deposition welding method for producing coating layers (80) on opposing surfaces (74) of a component (70) in that on each surface (74), an additive material (2), in particular a pulverulent additive material, is directed onto the respective surface (74) along a processing trajectory, in particular a spiral-shaped processing trajectory, wherein the additive material (2) and the component (70) are heated along the processing trajectory by means of a laser beam (1) such that the additive material (2) connects to the component (70) upon striking the respective surface (74), and the coating layers (80) are at least temporarily simultaneously produced on the opposing surfaces (74).

Description

[0001] Title: Laser cladding process for the production of

[0002] Coating layers on opposite surfaces of a component

[0003] Description

[0004] The invention relates to a laser cladding method for producing coating layers on opposing surfaces of a component, a device for carrying out the laser cladding method and a component with opposing surfaces which are coated with coating layers, wherein the coating layers are produced by means of the laser cladding method.

[0005] Conventional laser cladding is out of date

[0006] This technique is well known. The surface of a component is melted using a laser beam, and a powdered filler material is added to the resulting melt pool. The powder is then also melted in the melt pool, so that after the molten powder material and the surface have solidified, a material layer is formed that is bonded, in particular by melt metallurgy.

[0007] Depending on the application, this process can be performed at various points on the surface or across a larger, contiguous area of ​​the workpiece surface, allowing 3D shapes to be applied using laser cladding. Furthermore, multiple layers of different materials can be built up on top of each other on the surface. When metallic material is applied, the deposition process is also referred to as "laser metal deposition" (LMD for short). Typical applications for laser cladding include repair, coating, and joining techniques.

[0008] So-called extreme high-speed laser cladding (EHLA for short) is already known from DE 10 2011 100 456 B4. According to this method, a significant increase in the achievable processing speed is achieved compared to conventional laser cladding by supplying at least one filler material in completely molten form to a laser-filler material interaction zone present on a surface to be processed, in particular to an at least partial molten bath. For this purpose, the filler material, which is initially in powder form, is melted by means of a laser beam at a distance greater than zero from the molten bath and then supplied to the molten bath in completely liquid form. The melting of the filler material, in particular the powder, at the aforementioned distance from the molten bath and the heating of the molten bath can be carried out by the same laser beam.The laser beam shining onto the molten bath also melts the filler material at the specified distance from the molten bath. This occurs by moving the molten bath and a focus of the laser beam parallel to each other relative to the surface at a speed of at least 20 m / min. Furthermore, in the case of a powdered filler material, the powder density can be adjusted so that the laser beam power in the molten bath is less than 60% of the laser power before the laser beam comes into contact with the powder. In this way, the EHLA process can significantly increase the processing speed of the laser cladding process.

[0009] In some applications, the coating is applied to opposite surfaces or sides of the component. For this purpose, it is known to turn the component over after coating one surface and then coat the other surface. Accordingly, in the prior art, the component is coated on one side only.

[0010] Particularly when high laser powers of, for example, more than 4 kW are used, the components can bend under the thermal energy input during laser material processing. Experts refer to this as so-called shielding (the word comes from the fact that the shape of a distorted component, for example a distorted brake disc, when viewed from the side, is reminiscent of an umbrella). In addition, tensile stresses arise on the component surface due to material shrinkage during solidification and cooling of the coating produced in the prior art, in particular by "High Speed ​​Laser Metal Deposition" (HS-LMD for short). This causes a large proportion of component distortion, the so-called shielding. As a result of this shielding, uneven layer thicknesses arise and, in some cases, a very large amount of material has to be welded on in order to create a shield after the component has been ground (so-calledsurface finish) to obtain a dimensionally accurate, plane-parallel component.

[0011] The invention is based on the object of reducing the above-mentioned disadvantages in a laser deposition welding process, in particular of improving the quality of the component produced.

[0012] The object is achieved by a laser cladding method according to claim 1. Accordingly, a laser cladding method is proposed for producing coating layers on opposing surfaces of a component, in which on each surface a filler material, in particular in powder form, is directed onto the respective surface along a processing trajectory, in particular a spiral one, wherein the filler material and the component are heated along the processing trajectory by means of a laser beam, so that the filler material bonds to the component (to form the respective coating layer or at least a part thereof on the respective surface) upon impact with the respective surface. The coating layers on the opposing surfaces are produced at least temporarily simultaneously.

[0013] By machining the component simultaneously on both sides according to the invention, it has been shown that shielding can be effectively avoided or at least reduced. This allows for symmetrical thermal loading of the component, thereby reducing the thermal distortion that causes shielding during machining. Symmetrical tensile stresses are also generated on both surfaces or sides of the component.

[0014] Another advantage is that the cycle time for producing the coating layers can also be reduced. The cycle time for producing the two coatings on the opposing surfaces of the component is comparatively long in the prior art due to the one-sided processing. Additional time is also required for turning and re-clamping the component. To shorten the cycle time, multiple laser deposition welding fixtures can be used, allowing multiple components to be coated on one side in parallel. However, the system costs for maintaining multiple laser deposition welding fixtures are correspondingly high.According to the invention, the simultaneous processing of both surfaces of the component now allows the cycle time to be more than halved, since not only can the two coating layers be produced completely simultaneously, but there is also no need to re-clamp the component. Likewise, if the same laser power is used for each side of the wafer, the number of devices required can also be halved. Simultaneous production at least for some of the time means that simultaneous production must take place at least for a certain minimum period of time. For example, the minimum period of time can be at least half or at least three-quarters of the production time required to produce a coating layer on one of the surfaces.The reason for this is that, due to the inertia of the component's heat transfer, it is not absolutely necessary for the coating layers to be produced simultaneously at all times. Nevertheless, it is naturally preferable for the coating layers on both surfaces of the component to be produced essentially simultaneously, i.e., for coating to begin and end at the same time, in order to achieve the shortest cycle time.

[0015] In particular, it can be provided that in the laser cladding process a laser-filler material interaction zone is created on the surface of the component, in particular an at least partial melt pool, with at least one at least partially molten filler material by means of a laser beam radiating onto the laser-filler material interaction zone. In this case, the at least one filler material can be melted by means of the respective laser beam at a distance from the respective laser-filler material interaction zone on the surface of the component, so that the at least one filler material is supplied to the respective laser-filler material interaction zone in at least partially molten form.In this respect, in particular, a further laser-filler material interaction zone is present at a distance from the surface of the component, in which the filler material, in particular in powder form, is already melted and impinges on the surface of the component. In this respect, this description also distinguishes between the laser-filler material interaction zones on the opposite surfaces of the component and the further laser-filler material interaction zones at a distance from the surfaces of the component.

[0016] It can be provided that the points of incidence of the laser beams on the surfaces are moved along the processing trajectory or the surfaces at a relative speed of at least 20 m / min. The relative speed is the speed at which the surface to be coated moves relative to the point of incidence of the laser beam on the surface. The laser beam radiates onto the surface in such a way that a laser-filler material interaction zone, in particular an at least partial melt pool, is created on the surface. One could therefore also say that the point of incidence and thus the laser-filler material interaction zone are displaced along the surface at a speed of at least 20 m / min.The advantage of this high relative speed is that the component is heated as evenly as possible over its circumference, so that no significant local thermal distortions occur on the circumference of the component.

[0017] Furthermore, it can be provided that the component is rotationally symmetrical, in particular as a disk, and is rotated about a rotation axis, in particular during the production of the coating layers. The component can, for example, be a

[0018] Brake disc, sliding disc, friction disc or similar, as can be used in various applications, for example in motor vehicles. The surfaces to be coated can each be circular ring-shaped surfaces. Accordingly, the rotation of the disc about its axis of rotation allows the disc to be coated all the way around. For this purpose, the disc can be attached to a shaft of a corresponding drive, for example an electric motor, which sets the disc in rotation. In addition, the points of incidence of the laser beams can be moved, in particular in a linear movement. In particular, they can be moved in a plane above the disc. This can be done, for example, by a linear drive on processing heads which emit the laser beams.The orientation of the feed of at least one additional material can also be shifted together with the irradiation points of the laser beams.

[0019] Furthermore, it can be provided that the at least one filler material is in powder form before melting by means of the laser beams. The filler material can be metallic. In addition to a metallic filler material, other materials can also be present which are to be incorporated into the coating layer. Furthermore, different metals can also be processed. Alternatively, it is conceivable for the filler material to be in the form of wire, tape, or sheet metal strip. However, feeding powdered filler material to the laser beam for melting, so that it is fed to the melt bath in a substantially completely molten form, has proven to be particularly advantageous. Furthermore, it can be provided that the at least one filler material is made available to the respective laser beam by at least three injectors per surface of the component.Particularly preferred are 3 to 21 injectors, and most preferably 7 to 14 injectors per surface or side of the component. This allows a very symmetrical focus of the filler material, in particular powder focus, to be created on the surface, which can improve the quality of the resulting coating layer.

[0020] Furthermore, it can be provided that an average powder efficiency with powdered filler material of all injectors combined is at least 85%. The powder efficiency indicates how much of the supplied powder is melted. Powder loss can thus be reduced. This can be achieved, among other things, by using injectors that can be used at an angle of 90° to the direction of gravity.

[0021] Furthermore, it can be provided that the injectors are supplied with powder from a corresponding powder conveyor via two or more supply lines, which can be directed from the injectors in two or more clusters via a distributor component. The required powder mass flow can thus be distributed among parallel powder feed lines. This achieves a particularly uniform powder mass flow and thus produces particularly uniform coating layers.

[0022] The injectors can advantageously be designed as tubes. In particular, they can be designed as hard metal tubes to provide high resistance to both the filler material and the high temperatures emanating from the laser-filler material interaction zones. Another advantage of tubes is the particularly good flow of any conveying gas through them, allowing the filler material to be fed from a suitable conveyor or reservoir to the laser beams at a distance from the surfaces.

[0023] Furthermore, it can be provided that the exit angle of the injectors relative to a perpendicular to the respective surface of the component is less than 60°, in particular less than 50°, and most particularly less than 40°. It has been shown that surface waviness on welded coating layers is thus particularly minimal.

[0024] Furthermore, it can be provided that the at least one additional material is supplied to the respective laser beam by means of a conveying gas, wherein the conveying gas has in particular a relative atomic mass of at least 4, in particular at least 14, and / or a specific volume flow of at least 3.2 Nl / min per mm 2cross-sectional area. It has been shown that the conveying gas with the above parameters provides a sufficiently strong impulse and thus such a high filler material speed, in particular powder speed, that the filler material can be guided to the laser beam without significant influence from external factors, for example the gravity acting on the filler material, and thus in an optimal manner. Furthermore, it can be provided that the production of the coating layers of the component takes place in a direction from relatively inside the surfaces to relatively outside the surfaces. In the case of a disc as the component, the coating or the movement of the laser beam points takes place from radially inside or the inner diameter to radially outside or to the outer diameter. In this way, thermal expansion can be used to generate tensile stresses in the component, in particular the disc.Upon cooling, compressive stresses form in the welded coating layers. These are advantageous because compressive stresses counteract crack propagation in the welded coating layers.

[0025] Furthermore, it can be provided that the laser beam axes of the laser beams are inclined relative to the surfaces at an angle of incidence in the range of greater than 0° to 35°, in particular in the range of 5° to 30°. For this purpose, a main axis of the processing heads from which the laser beams are emitted can be inclined accordingly relative to the surfaces. Laser light reflected back from the component at the angle of incidence thus does not strike the processing head, but is deflected past it.

[0026] Furthermore, it can be provided that the laser power of a laser beam directed onto one of the surfaces is at most twice as high as the laser power of the laser beam directed onto the other of the two surfaces. In particular, it can be provided that the laser power of one laser beam is at most 30% higher than that of the other laser beam. It is particularly advantageous if the

[0027] The laser powers of the laser beams are essentially the same. This also ensures a high degree of thermal symmetry between the two surfaces or sides of the component. Shielding of a pane as a component can thus also be effectively avoided. Any grinding required during further processing of the pane to counteract the shielding can at least be reduced.

[0028] It can also be provided that the two laser beams are moved together relative to the component by a common feed unit. By implementing a common feed unit that can connect both processing heads of the laser beams via a support element, only one actuator is required for the linear movement of the beam points. The feed rate-to-feed path profile of the two laser beams thus corresponds to each other.

[0029] Furthermore, it can be provided that the two laser beams are moved with different feed rate-to-path profiles and / or that different amounts of filler material are applied to each surface, thereby creating different coating layer thicknesses on the opposing surfaces of the component. This makes it possible to straighten an already shielded component, in particular a shielded pane, using layers of different thicknesses.

[0030] However, it can also be provided that the two laser beams are each moved with different feed rate vs. travel profiles, with the different feed rate vs. travel profiles running in opposite directions to one another. For this purpose, the two processing heads of the different laser beams can also be equipped with separate feed units, i.e. linear drives, for each surface. This way, one laser beam can have a feed rate vs. travel profile that decreases over the path in the feed direction, while the other laser beam can have a feed rate vs. travel profile that increases over the path in the feed direction. The gradients of the different profiles can be the same. This way, wedge-shaped coating layers are created in the cross-section through the component, which are aligned in wedge shapes opposite to one another.The advantage of using such different feed rate-to-feed path profiles is that existing or newly created shielding of the component can be compensated. Advantageously, the coating layers can also be applied in multiple layers, particularly by repeated laser deposition welding, in order to build up coating layers that are as homogeneous as possible in terms of thickness, which, in the brake disc example, ensure maximum service life.

[0031] It is also possible for the intensity distributions of the laser beams to be generated at least approximately in the form of a so-called flat top. In comparison to a Gaussian laser power distribution, it has been shown that this produces lower roughness on the coating layers. In particular, the intensity distributions can be approximately in the form of a flat top with an area of ​​reduced intensity in the center (I_max (maximum intensity) > l_core (intensity in the core) > 0). This opens up a particularly large process window for the laser cladding process. This allows the power application to the two surfaces to be set sufficiently thermally symmetrical for the coating.

[0032] Furthermore, a sensor device, such as a camera, in particular a VIS camera or IR camera, or a pyrometer, can be arranged coaxially oriented in the measuring direction or viewing direction of the laser beam. This allows for simultaneous observation of the coating process. The coating process can thus be controlled in a closed control loop of a corresponding control device.

[0033] Furthermore, it can be provided that the laser beam axes are moved congruently to one another. The laser beam axes thus coincide (in their extension) during processing. In other words, the irradiation points of the laser beams or, overall, the process zones of the coating with the melt pools can be arranged mirror-symmetrically to the component plane. This allows for particularly highly thermally symmetrical processing of the component.

[0034] Alternatively, it can also be provided that the laser beam axes of the laser beams are moved incongruently to one another. The laser beam axes therefore do not coincide during processing. Instead, the radiation points of the laser beams or the process zones are offset from one another laterally to the linear movement of the laser beam axes. This has the advantage that the opposing processing heads cannot irradiate one another, which increases safety. The object mentioned at the outset is further achieved by a component according to claim 15. The component has opposing surfaces which are coated with coating layers, the coating layers being produced by means of a laser deposition welding method according to the invention.

[0035] In this case, features that are described herein with regard to the laser cladding process also apply with regard to the component and vice versa.

[0036] The object mentioned at the outset is also achieved by a device according to claim 16. The device is set up to carry out a laser deposition welding method according to the invention, wherein the device has at least one laser for generating the laser beams, and wherein the device has at least one filler material conveyor for conveying the at least one filler material at a distance from the surfaces of the component, in particular at a distance of the respective laser-filler material interaction zones, in particular melt pools, on the surfaces of the component, to the laser beams.

[0037] In this case, features that are described herein with regard to the laser cladding process and the component also apply with regard to the device and vice versa.

[0038] The at least one laser can preferably have a laser power of more than 4 kW, in particular more than 12 kW and up to 24 kW. It can be, for example, a laser with a wavelength of approximately 1 pm (fiber laser, disk laser), approximately 0.8 pm (diode laser) or 0.5 pm (green converted). A laser light cable with a 2 inl fiber can be used, whereby a core diameter of 600 pm to 1000 pm or diameter ratios of 200 pm / 700 pm and 300 pm / 1000 pm can be implemented. An adjusting device (wedge switch) can also be used to adjust the core-cladding ratio of the 2 inl fiber. A processing head of the laser can have a focus of approximately 1.4 mm to approximately 8 mm to image the fiber end of the 2 inl fiber into the area of ​​a powder focus or onto the surfaces.

[0039] The at least one filler material conveyor can be designed as a powder conveyor and have a powder nozzle for forming a powder focus. The powder nozzle can, as described above, be implemented using injectors, in particular with multiple injectors as a multi-jet nozzle. The conveying gas can be, for example, an inert gas such as argon or helium, or a gas mixture thereof. A process protective gas can also be supplied to the process.

[0040] It is now possible to use one laser and one filler material conveyor in the device for each surface of the component, so that essentially the entire structure of the device, including the additional peripherals mentioned above, such as the linear drive, injectors, etc., and with the exception of the drive for rotating the component, can be mirrored on both sides of the component. However, it is also possible to use a common laser and / or filler material conveyor for both surfaces or sides of the component in order to keep the costs of the device low. For this purpose, the laser beam can be split and directed to both surfaces. The filler material conveyor can also be designed to convey the filler material to both sides. However, at least one processing head is provided for each side or surface of the component, each of which allows optical focusing of the laser beam on the respective surface.Furthermore, a powder feed is provided, for example in the form of at least one injector per surface. Furthermore, a clamping device can be provided, by means of which the component can be clamped, in particular vertically, between the two processing heads and in particular also the injectors for processing. The clamping device can be provided as a component on the aforementioned shaft for rotating a disk.

[0041] Further details and advantageous embodiments of the invention can be found in the following description, on the basis of which embodiments of the invention are described and explained in more detail.

[0042] It shows :

[0043] Figure 1 is a schematic view of a structure of a

[0044] Device for laser cladding;

[0045] Figure 2 is a plan view of a component according to a

[0046] From an exemplary embodiment of the invention;

[0047] Figures 3a, 3b are schematic views of a laser cladding process;

[0048] Figure 4 shows a schematic view of a laser deposition welding method according to the invention in accordance with a first exemplary embodiment; Figure 5 shows a schematic view of a laser deposition welding method according to the invention in accordance with a second exemplary embodiment; and Figures 6-8 show schematic views of different arrangements of laser processing heads relative to the component to be coated.

[0049] In the following description and in the figures, the same reference symbols are used for identical or corresponding features.

[0050] Figure 1 shows an overall device 10 for laser cladding. The device 10 comprises a laser 12 for generating a laser beam 1. The laser beam 1 generated is fed to a light exit 16 via a fiber optic cable 14. The laser beam 1 generated in this way is then directed into parallel alignment in a collimating lens 18. The laser beam 1 then passes through a movable processing head 20 (incidentally, the light exit 16 and the collimating lens 18 can alternatively be arranged in the processing head 20 itself). A focusing lens (not shown) for concentrating the laser beam 1 is arranged within the processing head 20. After passing through the focusing lens, the laser beam 1 passes through a cylindrical section 22 and a funnel-shaped section 24 of the processing head 20, which also serve as a powder nozzle for a powdered filler material 2.

[0051] The entire assembly comprising light exit 16, collimation lens 18, and processing head 20 is arranged by means of a feed unit 30 so as to be movable linearly above a component 70 to be coated. To be precise, the feed unit 30 can be moved in the plane defined by an X-coordinate and a Y-coordinate above the component 70 (see Fig. 2). By way of example, the feed unit 30 in the present case comprises a linear drive 34 and an electric motor 32 which drives the linear drive 34. Furthermore, the device 10 comprises a rotation unit 90, which in the present case has a further electric motor 92 with a shaft 94 coupled thereto for rotating the component 70 attached thereto.The component 70 is designed here, for example, to be rotationally symmetrical, in particular as a brake disc, and is rotated about its axis of rotation 72, which coincides with the shaft 94, in the direction of rotation R shown during the coating of the component 70 with a coating layer 80, which will be explained in more detail later.

[0052] The device 10 further comprises a filler material conveyor 40 for conveying powdered filler material 2. In the filler material conveyor 40, the powder is mixed with a gas, in particular an inert gas such as nitrogen or argon, in order to generate a powder gas stream 4 for conveying the powder. In a distributor component 42, the powder gas stream 4 is distributed into several, in the present case, for example, three, feed lines 44, in particular feed hoses, and then flows into the cylindrical section 22 of the machining head 20. The section 24 of the machining head 20 has a double wall, wherein the powder gas stream is guided through the annular gap created thereby, so that the powder gas stream 4 flows between the two walls. The laser beam 1 and the powder gas stream 4 therefore run coaxially to each other through the sections 22 and 24.In the funnel-shaped section 24, the annular gap between the two walls tapers, so that the powder gas flow 4 leaves the funnel-shaped section 24 through a nozzle-like outlet formed thereby.

[0053] The device 10 further comprises a sensory measuring device 50. The measuring device 50 can, for example, be configured to carry out the light-section method in order to generate a height profile of the surface 74. For example, a light-section scan can be performed at 4 kHz. In particular, a height profile can be generated along a schematically shown projected light line 52.

[0054] Finally, the device 10 comprises a control device 60. This serves, on the one hand, to control the laser 12 and the filler material conveyor 40. Furthermore, it serves to control a control unit 62, which also belongs to the device 10 and is designed to control the electric motor 32 and the further electric motor 92. Furthermore, the control device 60 is configured to evaluate the measurement signals acquired by the measuring device 50.

[0055] Overall, the device 10 is designed to carry out the method described below:

[0056] The presently circular surface 74 of component 70 is coated by extremely high-speed laser deposition welding (EHLA) using the device 10. For this purpose, component 70 is first set in rotation by driving the shaft 94 by the additional electric motor 92.

[0057] Furthermore, the laser beam 1 is generated and projected onto the surface 74, wherein the laser beam 1 radiates onto the surface 74 at an incident point. As a result, a laser-filler material interaction zone 6, in particular an at least partial melt pool, is generated on the surface 74. Furthermore, a powder gas stream 4 is generated. After leaving the cylindrical section 24, the powdered filler material 2 of the powder gas stream 4 strikes the light path of the laser beam 1 during its flight phase. The filler material 2 and the laser beam 1 can be directed onto the surface 74 along a particularly spiral-shaped processing trajectory. For this purpose, the laser beams 1 and the filler material 2 and / or, as will be explained in more detail later using the example of rotation, the component 70 can be displaced or moved relative to one another. The filler material 2 is consequently heated by means of the laser beam 1 along the processing trajectory.As a result, the filler material 2 in the form of powder particles is at least partially or completely melted before they reach the surface 74 of the component 70. As a result, the at least partially melted filler material bonds with the component 70 upon impact with the surface 74 or the component 70, so that a coating layer 80 is produced. In particular, there is a further laser-filler material interaction zone (not labeled) at a distance from the surface 74 or the laser-filler material interaction zone 6 on the surface 74 (one could also say that the two interaction zones are connected to one another due to their respective thermal effects; for the sake of clarity, however, these are considered separately here).On this further laser-filler material interaction zone at a distance from the surface 74, the filler material 2 is already melted "in flight" to the surface 74, as explained above. The filler material is thus supplied to the laser-filler material interaction zone 6 on the surface 74 in at least partially or completely molten form. The component 70 is rotated so quickly about the rotation axis 72 that the point of incidence of the laser beam 1 on the surface 74 is displaced along the surface 74 at a speed of at least 20 m / min. As a result, the laser-filler material interaction zone 6 created on the surface 74 by means of the laser beam 1 is displaced along the surface 74 by at least 20 m / min.

[0058] The laser deposition welding process gradually produces the aforementioned coating layer 80. For this purpose, the laser beam 1 is moved bit by bit from radially outside to radially inside relative to the rotation axis 72 by means of the linear drive 34, so that the incident point of the laser beam 1 is moved in a spiral-shaped processing trajectory along the surface 74. Likewise, the laser-filler material interaction zone 6 on the surface 74 is guided in a spiral from radially outside to radially inside to produce the coating layer 80. As can be seen in Fig. 1, the surface 74 comprises a coated radially outer section 82 and an uncoated radially inner section 84. Figure 2 shows the component 70 in the form of a brake disk for a motor vehicle, the surface 74 having the coating layer 80 which has been produced by the method described above.Such a coating layer 80 is also produced on the opposite surface 74 or side of the component 70. For this purpose, it is known to turn the component 70 and to coat the other surface 74 on one side as well using the device 10 in Fig. 1. This can result in shielding of the disk-shaped component 70, as can be seen, for example, in Fig. 3a. The cycle time for producing the two coating layers 80 on the opposite surfaces 74 of the component 70 is also comparatively long, since the coating layers 80 are each produced on one side. Additional time is also required for turning and clamping the component 70. In order to shorten the cycle time, several devices 10 can be used so that several components 70 can be processed in parallel. However, the system costs for maintaining several devices 10 are correspondingly high.

[0059] Figure 3a shows the laser cladding process for the component 70, similar to Fig. 1, in a schematic cross-sectional view. Unlike in Fig. 1, no processing head 20, as described with reference to Fig. 1, is used. Instead, a plurality of injectors 46, of which only two are shown here as an example, are used, by means of which the filler material 2, in particular as a powder gas stream 4, is fed directly to the laser beam 1. The injectors 46 are shown here as tubes, in particular hard metal tubes, by way of example. They can each be connected to the distributor component 42 by means of one, two or more feed lines 44. It is also possible for each injector 46 to have its own distributor component 42, wherein the distributor components 42 can in turn be connected to the filler material conveyor 40. As shown in Fig .As can also be seen in Figure 3a, the laser beam 1 is moved with its laser beam axis LA, in this example, in the X direction as the feed direction, whereby its irradiation point is also shifted in this direction. This occurs during the rotation R of the component 70 about the rotation axis 72.

[0060] In Fig. 3a, an exit angle a of the injectors 46 relative to a perpendicular of the respective surface 74, which here coincides, for example, with the longitudinal axis LA of the laser beams 1, is less than 60°. It has been shown that surface waviness of the coating layers 80 welded on this way is particularly low.

[0061] Figure 3b shows a modification of the beam guidance of the laser beam 1, in which the laser beam axis LA of the laser beam 1 is at an advantageous angle of incidence ß with respect to the surface 70, so that the laser beam 1 with its incident point is incident on the surface 70 at the angle of incidence ß. The angle of incidence ß here is, for example, 35°. The angle of incidence ß can be achieved in particular by appropriately arranging the processing head 20 relative to the surface 70, wherein the powder gas stream 4 can be guided in the processing head 20, as shown in Fig. 1, or can be guided outside the processing head 20, so that only the laser beam 1 is guided in the processing head 20 or exits therefrom.Advantageously, a laser beam 1 striking the surface 74 at the angle of incidence ß cannot be reflected back to the processing head 20 as laser light, but is directed past it.

[0062] Figure 4 shows a modified version of Fig. 3.

[0063] Embodiment of the laser deposition welding process, wherein here also a variant of the feeding of additional material 2 to the laser beam 1 with injectors 46 is shown in Fig. 3a, which can alternatively also be carried out with the processing head 20 according to Fig. 1. Here too, the laser beam axis LA of the laser beam 1 can be guided at the angle of incidence ß in Fig. 3b relative to the surface 74. Overall, the various embodiments of Figures 1 to 8 explained in detail here can be combined with one another as desired, provided this is technically expedient. For example, the structure of the device 10 in Fig. 4, which is not explained in detail, can have individual, several or all of the components of Fig. 1.

[0064] Unlike in Figs. 1 and 3a, in the laser cladding process of Fig. 4, the coating layers 80 are produced simultaneously on the opposite surfaces 74 of the component 70. As Fig. 4 shows, laser beams 1 are provided for this purpose from both sides or surfaces 74, with the additional material 2 being supplied accordingly via injectors 46. As a result, thermal loading and tensile stresses on the component 70 are distributed symmetrically across the opposite surfaces 74, whereby possible thermal distortion, which would otherwise lead to shielding of the component 70, can be prevented or at least reduced.

[0065] For example, a device 10 of Fig. 1 can be arranged with a mirrored structure opposite both surfaces 74. However, it is also possible for individual components of such a mirrored or double structure of the device 10 to be split, for example the laser 12, whose laser beam 1 can be used for processing on both surfaces 74, or for example the filler material conveyor 40. This is indicated in Fig. 4 in that, for the sake of clarity, only schematically and individually processing heads 20 are shown on each side of the surfaces 74, which are connected to a common laser 12 via corresponding fiber optic cables 14. As mentioned, this is only a schematic representation; of course, other components, as explained in detail in Fig. 1, can also be added to shape the laser beam 1.Also shown here as an example is a common filler material conveyor 40 with distribution components 42 for the injectors 46. For example, the injectors 46 are each connected to their respective associated distribution component 42 via only one supply line 44, although two or more supply lines 44 per injector 46 may also be provided.

[0066] Advantageously, in the embodiment of Fig. 4, a common feed unit 30 can also be provided for both processing heads 20 (and also the injectors 46) per surface 74, which is not shown in Fig. 4. Advantageously, only one control device 60 can be provided in order to ensure the simultaneous production of the coating layers 80 on both

[0067] Surfaces 74 to match each other, which is also not shown in Fig. 4.

[0068] As Fig. 4 further illustrates with the aid of diagrams next to the respective laser beams 1, which show the feed rate in the feed direction compared to the distance traveled in the feed direction X, i.e. in each case show a feed rate to feed distance profile of the respective laser beam 1 and thus of the processing, a constant feed rate over the distance is used here in order to apply a uniform or equally thick coating layer 80 in the feed direction X to both surfaces 74.

[0069] In Figure 5, in contrast to this, unevenly thick coating layers 80 are applied, specifically by means of opposing feed rate to feed path profiles. The left laser beam 1 in Figure 5 has a feed rate to feed path profile that decreases over the path in the feed direction X, whilst the right laser beam 1 in Figure 5 has a feed rate to feed path profile that increases over the path in the feed direction X. For example, the gradients of the different profiles are of equal magnitude. In this way, wedge-shaped coating layers 80 are produced that are visible in cross-section and are aligned in a wedge shape opposite to one another. The advantage of using such feed rate to feed path profiles is that existing or created shielding of the component 70 can be compensated for, as can be seen from the geometry of the component 70 in Figure 7.5, which is inclined to the left in its outer region in Fig. 5. Advantageously, the coating layer 80 can also be constructed in multiple layers, in particular by repeated laser deposition welding, in order to build up a coating layer 80 that is as homogeneous as possible in terms of thickness and which, in the exemplary embodiment of the brake disc, has a maximum service life.

[0070] Figures 6 to 8 show different possibilities for guiding the laser beam 1 or the processing trajectory or, associated therewith, the process zone with the laser-filler material interaction zone 6 and thus for producing the coating layers 80. The laser beam axis LA shown indicates the process zone or processing location at which the coating layer 80 is currently being produced and can be provided by a corresponding arrangement of the processing head 20 relative to the surfaces 74.

[0071] In Fig. 6, the laser beam 1 is advanced in the Y direction (see also Fig. 2). In Fig. 7, the laser beam 1 is advanced in the X direction (see also Fig. 2). Figs. 6 and 7 also have in common that the laser beam axes LA of the laser beams 1 coincide. This means that the laser beam axes LA of the laser beams 1 are moved congruently to one another. In this way, the coating layers 80 are produced at opposite parallel locations on the surfaces 74. This improves the thermally symmetrical processing of the component 70 and reduces the risk of shielding of the component 70. In Fig. 8, on the other hand, the coating layers 80 are produced at locations on the surfaces 74 that are offset in the X direction. The laser beam axes LA of the laser beams 1 are moved incongruently to each other, in particular offset from each other by a predefined lateral distance in the X-direction.This reduces the risk of the opposing processing heads 20 irradiating each other in order to provide a safe device 10 and a safe laser cladding process.

Claims

Claims: Laser cladding process for producing coating layers (80) on opposing surfaces (74) of a component (70), in which an additive material (2), in particular a powder, is directed along a processing path, in particular a spiral path, onto the respective surface (74) on each surface (74), wherein the additive material (2) and the component (70) are heated along the processing path by means of a laser beam (1), so that the additive material (2) bonds with the component (70) upon impact with the respective surface (74), characterized in that the coating layers (80) on the opposing surfaces (74) are produced at least temporarily simultaneously.Laser cladding process according to one of the preceding claims, wherein the point points of the laser beams (1) on the surfaces (74) along the processing path are moved at a relative speed of at least 20 m / min. Laser cladding process according to claim 1 or 2, wherein the component (70) is rotationally symmetrical, in particular as a disk, and is rotated about a rotational axis (72) during the production of the coating layers (80). Laser cladding process according to any one of the preceding claims, wherein the at least one filler material (2) is present as a powder prior to melting by means of the laser beams (1). Laser cladding process according to any one of the preceding claims, wherein the at least one filler material (2) is supplied to the respective laser beam (1) by at least three injectors (46) per surface (74) of the component (70). Laser cladding process according to claim 5, wherein the injectors (46) are designed as tubes, in particular as hard metal tubes. Laser cladding process according to claim 5 or 6, wherein an exit angle (a) of the injectors (46) relative to a perpendicular of the respective surface (74) of the component (70) is less than 60°.Laser cladding process according to one of the preceding claims, wherein the at least one filler material (2) is supplied to the respective laser beam (1) by means of a conveying gas, wherein the conveying gas in particular has a relative atomic mass of at least 4 and / or a specific volume flow rate of at least 3.2 Nl / min per mm. 2 has a cross-sectional area. Laser cladding process according to one of the preceding claims, wherein the production of the coating layers (80) of the component (70) in the direction from relatively inside the surfaces (74) to relatively outside the surfaces (74). Laser cladding process according to one of the preceding claims, wherein laser beam axes (LA) of the laser beams (1) are inclined at an angle of incidence (β) in the range of greater than 0° to 35° relative to the surfaces (74). Laser cladding method according to one of the preceding claims, wherein the laser power of a laser beam (1) directed at one of the surfaces (74) is at most twice as great as the laser power of the laser beam (1) directed at the other of the two surfaces (74). Laser cladding method according to one of the preceding claims, wherein the two laser beams (1) are moved together relative to the component (70) by a common feed unit (30).Laser cladding process according to one of the preceding claims, wherein the two laser beams (1) are each moved with different feed rate-to-path profiles and / or different amounts of the filler material (2) are supplied to each surface (74), thereby producing different layer thicknesses of the coating layers (80) on the opposing surfaces (74) of the component (70). Laser cladding process according to one of the preceding claims, wherein the two laser beams (1) each move with different feed rate-to-path profiles. The procedure will be carried out, whereby the different The forward thrust velocity and forward thrust path profiles are inversely proportional to each other.

15. Component (70) with opposing surfaces (74) which are coated with coating layers (80), wherein the coating layers (80) are produced by means of a laser cladding process according to one of the preceding claims.

16. Device (10) for performing a laser cladding process according to one of claims 1 to 14, wherein the device (10) includes at least one laser (12) for generating the laser beams (1), and wherein the device (10) has at least one additive material conveyor (40) for conveying the at least one additive material (2) at a distance from the surfaces (74) of the component (70) to the laser beams (1).

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