Method and system for warp-compensating laser deposition welding

Abstract

The present invention relates to a method for laser deposition welding a functional layer (110) onto a workpiece (100), in particular a brake disc, by means of a primary laser beam (51) and a secondary laser beam (52), said method comprising the following steps: laser deposition welding of a first workpiece side (120) in an initial configuration in which a primary initial power (P1) is applied to the primary laser beam (51) and a secondary initial power (P2) is applied to the secondary laser beam (52); laser deposition welding of a second workpiece side (130), opposite the first workpiece side (120), in a modified configuration in which a secondary modification power (P2, mod), which differs from the secondary initial power (P2), is applied to the secondary laser beam (52). The invention further relates to a system in which four jet nozzles are connected to one another via a production line.

Description

[0001] Process and system for distortion-compensating laser cladding

[0002] Technical area

[0003] The present invention relates to a method for laser deposition welding of a functional layer onto a workpiece, in particular a brake disc, by means of a primary laser beam and a secondary laser beam, as well as a system for distortion-compensating laser deposition welding of a functional layer onto a workpiece.

[0004] State of the art

[0005] Laser cladding is used in repair, coating, and / or joining technology, for example. A distinction can be made between conventional laser cladding (laser metal deposition (LMD), direct metal deposition (DMD), or direct energy deposition (DED)) and so-called high-speed laser cladding (HS-LMD or extremely high-speed laser cladding (EHLA)). HS-LMD processes are described, for example, in published patent applications DE 102011 100 456 A and DE 10 2018 130 798 A1. Furthermore, published patent application DE 10 2022 100 173 A1 discloses a method for additive manufacturing in which a first laser beam from a nozzle unit and a second laser beam from a separate head are directed onto a workpiece in order to additively apply a powdered build material.

[0006] A functional layer can be applied to a workpiece using laser cladding. This generally increases the load-bearing capacity of the workpiece processed by laser cladding compared to an unmachined workpiece. The functional layer can serve, for example, as a wear-resistant layer. The application of the functional layer can be based on a diffusion process, partial melting and / or melting of a workpiece surface, the application of a filler material, and subsequent cooling, so that a matrix structure with hard material particles is firmly bonded to the material surface. Laser cladding has a thermal effect on the workpiece, which can lead to distortion. This can impair the desired increase in load-bearing capacity. Description of the invention

[0007] Based on the prior art, it is an object of the present invention to provide an improved method and system for laser metal deposition welding. The invention is particularly aimed at minimizing or completely compensating for thermal distortion of a workpiece. It can also aim at efficient workpiece processing while meeting the highest quality standards.

[0008] The problem is solved by a method and a system having the features of the independent claims. Advantageous further developments emerge from the dependent claims, the description, and the figures.

[0009] Accordingly, a method is provided for laser deposition welding of a functional layer onto a workpiece, in particular a brake disc, using a primary laser beam and a secondary laser beam. The functional layer can be constructed in two layers, comprising an underlying adhesion layer and a wear-resistant layer arranged thereon. The adhesion layer can be formed from a metallic material, and the wear-resistant layer can comprise, in addition to the metallic material, hard material particles as a matrix, for example carbides, in particular tungsten carbide, titanium carbide, in particular with iron chromium as a binder. In particular, the hard material particles made of titanium carbide and iron chromium enable laser deposition welding with high laser powers without the risk of cracking. Therefore, particularly high tolerances in laser power variation are possible for these hard material particles.Alternatively, the functional layer can be single-layered and consist exclusively of a wear-resistant layer. Rotationally symmetrical components such as a brake disc, a hydraulic cylinder, a printing roller, or a plain bearing are particularly suitable as workpieces. The brake disc can have a wheel side with a hub cup and a hub side opposite the wheel side. The primary laser beam and / or the secondary laser beam can have an annular beam and a core beam to achieve a plateau-shaped intensity distribution of the laser beam ("top hat"), so that the respective laser beam has a reduced intensity in a core area compared to an edge area. The primary laser beam and the secondary laser beam can originate from the same laser source. The primary beam and the secondary beam can create multiple process zones for laser cladding.They can be arranged in close proximity to each other to ensure a geometrically dense arrangement to reduce thermal losses between the two laser beams. The primary laser beam can interact with a powdered filler material to create the functional layer. The secondary laser beam can be used for pre- or post-processing of the process area processed by the primary laser beam. The secondary laser beam can be positioned in front of or behind the primary laser beam in a feed direction along which a beam nozzle moves relative to the workpiece.

[0010] The method comprises the step of laser deposition welding a first workpiece side, in particular a wheel side of the brake disc, in an initial configuration, wherein, in the initial configuration, the primary laser beam is subjected to a primary initial power and the secondary laser beam is subjected to a secondary initial power. The primary initial power and / or the secondary initial power can be constant during the machining of the first workpiece side. The primary initial power can be lower than the secondary initial power to produce metallurgical advantages in the bond between the powdered filler material and the workpiece. Alternatively, the primary initial power can be equal to or higher than the secondary initial power.

[0011] The method further comprises the step of laser deposition welding a second workpiece side opposite the first workpiece side, in particular a hub side of the brake disc, in a modified configuration, wherein in the modified configuration the secondary laser beam is subjected to a secondary modification power that is different from the secondary initial power. The secondary modification power can be at least partially lower than the secondary initial power. Thus, a melt pool created by the modified configuration on the second workpiece side can have a lower temperature than a melt pool created by the initial configuration on the first workpiece side, which reduces the thermal distortion of the workpiece due to the modified configuration, in particular because the lower melt pool temperature results in less shrinkage.The secondary modification power can also be, at least in part, higher than the secondary initial power. Thus, the melt pool created by the modified configuration on the second workpiece side can have a higher temperature than the melt pool created by the initial configuration on the first workpiece side, which increases the thermal distortion of the workpiece due to the modified configuration in order to compensate for a corresponding distortion of the workpiece due to the initial configuration. The secondary modification power can be constant or vary during the processing of the second workpiece side. The step of laser deposition welding the second workpiece side can be performed using a different beam nozzle than the step of laser deposition welding the first workpiece side. The method according to the disclosure is not limited to implementation using the same beam nozzle.In this way, distortion-compensating laser cladding is possible. The workpiece may already have a distortion before the first workpiece side is machined, which is further increased by laser cladding in the initial configuration. Laser cladding in the modified configuration can compensate for the distortion that arises during the process and / or that was already present before the process. The invention can utilize the behavior that the distortion increases with increasing power input to the workpiece, without having to accept qualitative changes in the functional layer. The secondary laser beam can assume the function of pre- or post-processing, so that its variation has no effect or only an indirect effect on the quality of the functional layer melted by the primary laser beam.However, by varying the power of the secondary laser beam from the secondary initial power to the secondary modification power, the total power input, especially the heat input, of the primary laser beam and the secondary laser beam into the workpiece can be influenced. Heat input can be primarily responsible for distortion, so varying the power of the secondary laser beam has proven to be a suitable parameter for compensating for distortion. Depending on the secondary modification power, the shrinkage of the functional layer can be increased or reduced to adjust the distortion of the brake disc.

[0012] In one embodiment, the secondary modification power is adjusted depending on the distortion of the workpiece in order to counteract the distortion. The secondary modification power can be used to influence the thermal input of the secondary laser beam into the workpiece, which, together with knowledge of the component's geometry, can be used to compensate for the distortion. The component's geometry can be inferred from empirical data.

[0013] In addition or alternatively to the empirical data, the method in one embodiment may include the step of detecting a workpiece geometry, wherein the secondary modification power is adjusted based on the detected workpiece geometry. The detection can be performed tactilely or optically, for example, with a light section sensor, thus a line laser, or camera-based. Taking the detected workpiece geometry into account when adjusting the secondary modification power further contributes to minimizing workpiece distortion.

[0014] In one embodiment, the workpiece geometry is acquired before and / or after laser deposition welding of the first workpiece side in the initial configuration. During the acquisition before laser deposition welding of the first workpiece side, deviations of the workpiece from the ideal geometry in the initial state are recorded. This increases the geometric tolerance within which the process can be carried out. During the acquisition after laser deposition welding of the first workpiece side, the distortion caused by the initial configuration is taken into account.

[0015] In one embodiment, the method further comprises the step of detecting a temperature of the workpiece, wherein the secondary modification power is adjusted based on the detected temperature. For example, the temperature in, before, or after the process zone can be detected using a pyrometer in order to draw conclusions about the melt pool and the distortion caused by it. These conclusions can be incorporated into the determination of the secondary modification power in order to enable process-accurate distortion compensation. The temperature can be detected not only with a pyrometer but also with a temperature sensor.

[0016] In one embodiment, the secondary modification power varies over a temporal process profile to compensate for non-linear distortion. Thus, a higher secondary modification power may be present at a location on the component where increased distortion exists than at a location on the component machined at a different time where less distortion exists. Such modeling of the secondary modification power can be particularly advantageous when the component is a two-component component that exhibits inhomogeneous distortion properties. The variation in the secondary modification power can be preset or in response to a condition detected immediately beforehand.

[0017] In one embodiment, the workpiece is substantially rotationally symmetric, such as a brake disc, and the secondary modification power increases with increasing radial distance from the workpiece's rotational axis. Thus, it is possible to respond to distortion that increases with increasing radial distance.

[0018] In one embodiment, the primary laser beam is operated at the same primary initial power in the initial configuration and the modified configuration. Thus, the interaction of the powdered filler material with the primary laser beam can be unaffected by the modified configuration. If the secondary modification power is lower than the secondary initial power, in this embodiment, the total laser power, which is composed of the laser powers of the primary beam and the secondary beam, is lower in the modified configuration than in the initial configuration. If the secondary modification power is higher than the secondary initial power, in this embodiment, the total laser power in the modified configuration is higher than in the initial configuration. With the constant laser power of the primary laser beam, the total laser power varies.In an alternative embodiment to the constant laser power of the primary laser beam, the total laser power of the primary laser beam and the secondary laser beam remains the same in the initial configuration and the modified configuration, so that the power of the primary laser beam in the modified configuration changes compared to the initial configuration by an amount equal to the difference between the secondary initial power and the secondary modified power. The difference between the secondary initial power and the secondary modified power is directly inversely proportional to the power of the primary beam in the respective configurations. It should be noted that the secondary laser beam in this configuration can only be varied by an amount by which the primary laser beam can also be varied without compromising the weld quality.

[0019] In one embodiment, the primary laser beam and the secondary laser beam originate from the same laser source, wherein a power distribution between the primary laser beam and the secondary laser beam is continuously adjustable via a motorized adjustment unit, in particular a motorized wedge switch. The motorized adjustment unit is arranged in the beam path. If, for example, it extends halfway into the original beam, it can produce a primary laser beam and a secondary laser beam, each with the same power. The further the motorized adjustment unit is moved toward the edge of the original beam, the greater the difference between the primary beam and the secondary beam. The continuous adjustment is particularly suitable for responding precisely to a previously detected distortion.

[0020] In one embodiment, after laser deposition welding of the first workpiece side in the initial configuration, the workpiece is rotated about a transverse axis orthogonal to a rotational axis of the workpiece in order to perform laser deposition welding of the second workpiece side in the modified configuration. The rotation about the transverse axis can be performed using a rotation module. Thus, if the first workpiece side and the second workpiece side are machined with the same jet nozzle, there is no need to move the jet nozzle to the opposite side. If the first workpiece side and the second workpiece side are machined with different jet nozzles, rotating about the transverse axis ensures that the jet nozzles are aligned identically to one another.

[0021] In one embodiment, a first adhesion layer is applied by means of laser deposition welding of the first workpiece side in the initial configuration, and a second adhesion layer is applied by means of laser deposition welding of the second workpiece side in the modified configuration. The first adhesion layer and / or the second adhesion layer can be homogeneously constructed from a metallic material. In one embodiment, the method can further comprise the step of laser deposition welding of the first workpiece side in a wear configuration, wherein in the wear configuration the primary laser beam is operated with a primary wear power and the secondary laser beam with a secondary wear power in order to apply a first wear-resistant layer to the first adhesion layer.In addition to the metallic material, the first wear-resistant layer can comprise hard material particles as a matrix, for example carbides, in particular tungsten carbide, titanium carbide, in particular with iron chromium as a binder. In particular, the hard material particles made of titanium carbide and iron chromium enable laser cladding with high laser powers without the risk of crack formation. The primary wear performance can be the same as the primary initial performance in one embodiment. It can also be different from the primary initial performance in another embodiment, if this is indicated, for example, by the detected geometry and / or the detected temperature. The secondary wear performance can be the same as the secondary initial performance in one embodiment, or can be different in another embodiment, if this is indicated, for example, by the detected geometry and / or the detected temperature.

[0022] In one embodiment, the method may further comprise the step of laser cladding the second workpiece side in a modified wear configuration, wherein in the modified wear configuration, a secondary laser beam is operated at a secondary wear modification power to apply a second wear-resistant layer to the second adhesion layer. The second wear-resistant layer may be constructed in a manner similar to the first wear-resistant layer. The secondary wear modification power may be the same as the secondary modification in one embodiment. In an alternative embodiment, it may also differ from the secondary modification power. This further contributes to distortion-free laser cladding.

[0023] The disclosure further relates to a system for distortion-compensating laser deposition welding of a functional layer onto a workpiece. The workpiece and the functional layer can be configured according to those of the method.

[0024] The system has a first blasting nozzle designed and configured to process a first workpiece side using a primary laser beam with a primary initial power and a secondary laser beam with a secondary initial power to apply a first bonding layer. The bonding layer may be formed from a metallic material. The primary initial power of the first blasting nozzle may be lower than the secondary initial power of the first blasting nozzle to create metallurgical advantages in the bond between the powdered filler material and the workpiece. Alternatively, the primary initial power may be equal to or higher than the secondary initial power.The primary laser beam and / or the secondary laser beam of the first beam nozzle can have a ring beam and a core beam to achieve a plateau-shaped intensity distribution of the laser beam, so that the respective laser beam has a reduced intensity in a core region compared to an edge region. The primary laser beam can interact with a powdered filler material to create the functional layer. The secondary laser beam can be used for pre- or post-processing of the processing location processed by the primary laser beam. The secondary laser beam can be located in front of or behind the primary laser beam in a feed direction along which a beam nozzle moves relative to the workpiece.

[0025] The system further comprises a second beam nozzle, which is provided and configured to process a second workpiece side opposite the first workpiece side using a primary laser beam and a secondary laser beam with a secondary modification power that differs from the secondary initial power, in order to apply a second adhesion layer. The second beam nozzle and the second adhesion layer can be configured correspondingly to the first beam nozzle and the first adhesion layer. The power of the primary laser beam of the second beam nozzle can be the same as the primary initial power of the first beam nozzle. The power of the primary laser beam of the second beam nozzle can also vary compared to the primary initial power. The secondary modification power can be at least partially lower than the secondary initial power.Thus, a melt pool created by the modified configuration on the second workpiece side may have a lower temperature than a melt pool created by the initial configuration on the first workpiece side, which reduces the thermal distortion of the workpiece due to the modified configuration, in particular because the lower melt pool temperature results in less shrinkage. The secondary modification power may also be, at least in part, higher than the secondary initial power. Thus, the melt pool created by the modified configuration on the second workpiece side may have a higher temperature than the melt pool created by the initial configuration on the first workpiece side, which increases the thermal distortion of the workpiece due to the modified configuration in order to compensate for a corresponding distortion of the workpiece due to the initial configuration.The secondary modification power can be constant or vary during machining of the second workpiece side.

[0026] The system further comprises a third jet nozzle, which is provided and configured to process the first workpiece side using a primary laser beam and a secondary laser beam with a secondary wear power that differs from the secondary modification power, in order to apply a first wear-resistant layer. In addition to the metallic material as a matrix, the first wear-resistant layer can comprise hard material particles, for example carbides, in particular tungsten carbide, titanium carbide, in particular with iron chromium as a binder. In particular, the hard material particles of titanium carbide and iron chromium enable laser cladding with high laser powers without the risk of crack formation. The third jet nozzle can be configured to correspond to the first jet nozzle. The secondary wear power can correspond to the secondary initial power.The power of the primary laser beam of the third beam nozzle can be the same or different from the primary initial power.

[0027] The system further comprises a fourth beam nozzle, which is provided and configured to process the second workpiece side using a primary laser beam and a secondary laser beam with a secondary wear modification power that differs from the secondary wear modification power, in order to apply a second wear protection layer. The second wear protection layer can correspond to the first wear protection layer. The fourth beam nozzle can be configured to correspond to the first beam nozzle. The secondary wear modification power can correspond to the secondary modification power. The power of the primary laser beam of the fourth beam nozzle can be the same as or different from the primary initial power.

[0028] The four jet nozzles of the system are connected to one another via a production line, in particular directly connected to one another, in order to enable distortion-compensating laser cladding without requiring manual operator interaction. The production line can be a conveyor belt mechanism that connects the four jet nozzles to one another. The conveyor belt mechanism can have a rotation module between the respective jet nozzles, which is provided and configured to rotate the workpiece between the respective jet nozzles along a transverse axis. The conveyor belt mechanism can further have a geometry detector, which is provided and configured to detect a distortion of the workpiece, wherein the secondary modification power or the secondary wear modification power is adjusted based on the detected distortion.The geometry detector can be a tactile or optical sensor or a camera. The conveyor mechanism can further comprise a temperature detector designed and configured to detect a temperature of the workpiece, wherein the secondary modification power or the secondary wear modification power is adjusted based on the detected temperature. The temperature detector can be a pyrometer or a temperature sensor.

[0029] The system enables distortion-compensating laser cladding. Laser cladding of the second jet nozzle with the secondary modification power and the fourth jet nozzle with the secondary wear modification power compensates for distortion that occurs during the process and / or that already existed prior to the process. In particular, the production line eliminates the need for manual operator intervention.

[0030] Short description of the characters

[0031] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. In the figures:

[0032] Figure 1 is a schematic view of a jet nozzle in laser cladding;

[0033] Figure 2 shows a system with a first and a second jet nozzle that process a workpiece from different sides;

[0034] Figure 3 shows a relationship between a laser power on the abscissa and a quality of a functional layer on the ordinate;

[0035] Figure 4 shows a schematic distortion of a brake disc after coating of the respective sides; and

[0036] Figure 5 shows a system with four jet nozzles and a production line.

[0037] Detailed description of preferred embodiments

[0038] In the following, exemplary embodiments are described with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals.

[0039] Figure 1 shows a jet nozzle 1 for laser material deposition welding along a feed direction 2. The feed direction 2 is the direction along which the jet nozzle 1 moves relative to a workpiece 100. It can result from a movement, in particular a rotational movement, of the workpiece 100, from a movement of the jet nozzle 1, or from a superposition of a movement of the workpiece 100 and the jet nozzle 1. The feed direction 2 and the correlating feed movement can be constant throughout the process. Alternatively, they can vary with the respective process stage. The workpiece 100 can be a rotationally symmetrical workpiece, such as a brake disc, a hydraulic cylinder, a printing roller, or a plain bearing. A functional layer 110 is applied to the workpiece 100 by means of laser material deposition welding.The workpiece 100 has a first workpiece side 120, for example a wheel side, and a second workpiece side 130, for example a hub side. A primary laser beam 51 and a secondary laser beam 52 emerge from a light channel. The blasting nozzle 1 is therefore a bifocal nozzle. A nozzle mouth 3 of the blasting nozzle 1 contains a powder unit 4, which can, for example, have a plurality of injector guides, into each of which a powder injector can be inserted. As an alternative to the individual injector guides, the powder unit 4 can have a powder annular gap channel. A powder-shaped filler material 140 is directed onto the workpiece 100 via the powder unit 4. The laser beams 51, 52 heat the workpiece 100 in such a way that a melt pool 150 forms on a material surface.In addition, the laser beams 51, 52 heat the powdered filler material 140, which in particular comprises hard material particles, for example carbides, and a matrix material. For this purpose, the laser beams 51, 52 can have a reduced core intensity. As soon as the molten pool 150 cools, the welded functional layer 110 forms, which can be composed, for example, of an adhesion layer and a wear-resistant layer. The welded functional layer 110 makes the material surface more resistant and increases its load-bearing capacity. The blasting nozzle 1 can also be adapted to conduct a process inert gas 160 at a radially outer section to shield a process zone and prevent oxidation.

[0040] Figures 2a and 2b show the blasting nozzle 1, which is moved relative to a workpiece surface along the feed direction 2 in order to provide the functional layer 110 on the workpiece 100. The blasting nozzle 1 processes the workpiece 100 using the primary laser beam 51 and the secondary laser beam 52. The workpiece 100 can be a brake disc. This has an axis of rotation 170 that corresponds to the axis of rotation of the brake disc. The axis of rotation 170 is orthogonal to a transverse plane. A transverse axis 180 runs in the transverse plane. Between the processing of the first workpiece side 120 and the processing of the second workpiece side 130, the workpiece 100 can be rotated about the transverse axis 150. Thus, the respective processing blasting nozzle is aligned identically when processing the first workpiece side 120 and the second workpiece side 130.Alternatively, the workpiece 100 can be moved between the processing of the first workpiece side 120 and the processing of the second workpiece side 130, so that the processing jet nozzle has to be moved to the other workpiece side instead.

[0041] Figure 2a shows the step of laser deposition welding the first workpiece side 120 in an initial configuration. In the initial configuration, the primary laser beam 51 is subjected to a primary initial power P1 and the secondary laser beam 52 to a secondary initial power P2. The initial configuration is selected to ensure an appropriate quality of the functional layer 110. The primary initial power P1 and / or the secondary initial power P2 can be constant during the processing of the first workpiece side 120. The primary initial power P1 can be smaller than the secondary initial power P2 in order to produce metallurgical advantages in the bond between the powdered filler material 140 and the workpiece 100. Alternatively, the primary initial power P1 can be equal to or greater than the secondary initial power P2.

[0042] Figure 2b shows the step of laser deposition welding the second workpiece side 130 in a modified configuration. In the modified configuration, the secondary laser beam 52 is subjected to a secondary modification power P2,mod that differs from the secondary initial power P2. The secondary modification power P2,mod can be at least partially lower than the secondary initial power P2. Thus, the melt pool 150 created by the modified configuration on the second workpiece side 130 can have a lower temperature than the melt pool previously created by the initial configuration on the first workpiece side 120, which reduces the thermal distortion of the workpiece 100 due to the modified configuration, in particular because the lower melt pool temperature results in less shrinkage. The secondary modification power P2,mod can also be at least partially higher than the secondary initial power P2.Thus, the melt pool 150 created by the modified configuration on the second workpiece side 130 can have a higher temperature than the melt pool created by the initial configuration on the first workpiece side 120, which increases the thermal distortion of the workpiece 100 due to the modified configuration to compensate for a corresponding distortion of the workpiece 100 due to the initial configuration. The secondary modification power P2,mod can be constant or vary during the machining of the second workpiece side 130. The jet nozzles in Figures 2a and 2b can be the same component or different jet nozzles.

[0043] Figure 3 shows two diagrams that illustrate the different process windows depending on the type of beam nozzle used. The total laser power P, i.e. the sum of the laser powers of the primary laser beam 51 and the secondary laser beam 52, is plotted on the abscissa. The quality Q of the functional layer 110 is plotted on the ordinate. At the threshold value Q*, a sufficiently high quality of the functional layer 110 is guaranteed. Figure 3a shows the power spectrum AP1, within which a conventional beam nozzle that guides a single laser beam, i.e. a monofocal nozzle, ensures a sufficiently high quality of the functional layer. Figure 3b shows the power spectrum AP2, within which the bifocal nozzle that guides the primary laser beam 51 and the secondary laser beam 52 ensures a sufficiently high quality of the functional layer. The power spectrum AP2 is significantly larger than the power spectrum AP1.The invention takes advantage of this relationship by varying the total laser power P depending on the respective process stage and the respective workpiece side being machined in order to compensate for distortion on the one hand, but on the other hand not to fall below the threshold value Q* of the quality of the functional layer.

[0044] Figure 4 schematically shows the processing of a brake disc. The left column shows the brake disc in its initial state prior to laser deposition welding. In Figure 4, the brake disc exhibits no distortion in its initial state. In another embodiment, not shown, the brake disc exhibits distortion in its initial state. The middle column shows the brake disc after laser deposition welding of the first workpiece side 120 in its initial configuration. Exposure to the first workpiece side 120 of the primary initial power P1 of the primary laser beam 51 and the secondary initial power P2 of the secondary laser beam 52 has caused uniform distortion in Figures 4a and 4b. In Figure 4c, the underlying brake disc is a two-component brake disc, which, for example, has an aluminum hub cup and cast iron friction surfaces. This composition leads to non-linear distortion, as shown in the center of Figure 4c.The dashed line shows the brake disc in a distortion-free state to illustrate the distortion caused by laser deposition welding. The distortion shown is highly simplified and not to scale. The primary initial power P1 and the secondary initial power P2 can each be constant during the machining of the first workpiece side 120. The amount of the respective power P1, P2 can be variably adjustable. The primary initial power P1 can be smaller than the secondary initial power P2 in order to create metallurgical advantages in the bond between the powdered filler material 140 and the workpiece 100. Alternatively, the primary initial power P1 can be equal to or greater than the secondary initial power P2.

[0045] The right-hand column shows the brake disc after laser deposition welding of the second workpiece side 130. In Figure 4a, the configuration with which the second workpiece side 130 was machined corresponds to the initial configuration. Accordingly, in the case shown in Figure 4a, the brake disc is distorted after laser deposition welding of the second workpiece side. This can be remedied by applying the modified configuration to the second workpiece side 130 as disclosed, as shown in Figure 4b. Because the secondary modification power P2,mod deviates from the secondary initial power P2, a targeted influencing of the distortion is possible. Accordingly, the brake disc exhibits no or hardly any distortion after laser deposition welding of the second workpiece side 130.To counteract the nonlinear distortion of the two-component brake disc from Figure 4 c, the secondary modification power P2,mod is modulated in the case shown in Figure 4 c. In the radially inner region, where the brake disc exhibits less distortion, the secondary modification power P2,mod is lower than in the radially outer region, where the brake disc exhibits increased distortion. Thus, the modulated secondary modification power can be used to react to a nonlinear distortion of the workpiece 100 in order to ultimately obtain a component that is at least approximately distortion-free, as shown in the right-hand column of Figure 4 c.

[0046] Figure 5 shows a system with a first jet nozzle 1100, a second jet nozzle 1200, a third jet nozzle 1300, and a fourth jet nozzle 1400, which are connected to one another via a production line 1500. The four jet nozzles 1100-1400 can be structurally identical to one another. The first jet nozzle 1100 can process the first workpiece side 120 in the initial configuration, in which, for example, the first workpiece side 120 faces upward, in order to apply a first adhesive layer to the first workpiece side 120. Between the first jet nozzle 1100 and the second jet nozzle 1200, the workpiece 100 can be rotated by 180° about the transverse axis 180 so that, for example, the second workpiece side 130 faces upwards before the second jet nozzle 1200 processes the second workpiece side 130 with a secondary modification power different from the secondary initial power in order to apply a second bonding layer.Because the second blasting nozzle 1200 processes the workpiece 100 with the secondary modification power, any distortion caused by the first blasting nozzle 1100 can be compensated for. Between the second blasting nozzle 1200 and the third blasting nozzle 1300, the workpiece 100 can be rotated again by 180° about the transverse axis, so that, for example, the first workpiece side 120 faces upwards again. The third blasting nozzle 1300, with a secondary wear power different from the secondary modification power, can now apply a first wear-resistant layer to the first workpiece side 120 with the first adhesion layer. After the third blasting nozzle 1300, the workpiece 100 can again be rotated by 180° about the transverse axis 180, so that, for example, the second workpiece side 130 faces upwards again.Thus, a second wear protection layer can be applied to the second workpiece side 130 with the second adhesive layer using a secondary wear modification performance that differs from the secondary wear modification performance. Because the fourth jet nozzle 1400 processes the workpiece 100 with the secondary wear modification performance, any distortion caused by the third jet nozzle 1300 can be compensated. Consequently, the component 100 leaves the production line 1500 in two layers and without distortion.

[0047] The production line 1500 can be a conveyor belt mechanism. The conveyor belt mechanism can have a rotation module between the respective jet nozzles 1100-1400, which is provided and configured to rotate the workpiece between the respective jet nozzles 1100-1400 along the transverse axis 180. The conveyor belt mechanism can further have a geometry detector, which is provided and configured to detect a distortion of the workpiece 100, wherein the secondary modification power or the secondary wear modification power is set based on the detected distortion. The geometry detector can be a tactile or an optical sensor or a camera. The conveyor belt mechanism can further have a temperature detector, which is provided and configured to detect a temperature of the workpiece 100, wherein the secondary modification power or the secondary wear modification power is set based on the detected temperature.the secondary wear modification performance is set. The temperature detector can be a pyrometer or a temperature sensor.

[0048] Where applicable, all individual features presented in the embodiments may be combined and / or exchanged without departing from the scope of the invention.

[0049] List of reference symbols

[0050] 1 jet nozzle

[0051] 2 Feed direction 20 1100 first jet nozzle

[0052] 3 Nozzle mouth 1200 second jet nozzle 4 Powder unit 1300 third jet nozzle

[0053] 1400 fourth jet nozzle

[0054] 51 primary laser beam 1500 production line

[0055] 52 Secondary laser beam 25

[0056] P Total laser power 100 Workpiece P1 Primary initial power

[0057] 110 Functional layer P2 secondary initial performance

[0058] 120 first workpiece side P2,mod secondary modification power

[0059] 130 second workpiece side 30 AP1 Performance spectrum of the monofocal nozzle

[0060] 140 powdered filler material

[0061] AP2 Performance spectrum of the Bifokal150 melt pool nozzle

[0062] 160 process protective gas

[0063] Q Quality of the functional layer

[0064] 170 rotation axis

[0065] 35 Q* Threshold

[0066] 180 transverse axis

Claims

Claims 1 . Method for laser deposition welding a functional layer (110) onto a workpiece (100), in particular a brake disc, by means of a primary laser beam (51) and a secondary laser beam (52), comprising the following steps: Laser deposition welding of a first workpiece side (120) in an initial configuration in which the primary laser beam (51) is subjected to a primary initial power (P1) and the secondary laser beam (52) is subjected to a secondary initial power (P2); Laser deposition welding of a second workpiece side (130) opposite the first workpiece side (120) in a modified configuration in which the secondary laser beam (52) is subjected to a secondary modification power (P2,mod) different from the secondary initial power (P2).

2. The method according to claim 1, wherein the secondary modification power (P2,mod) is adjusted as a function of a distortion of the workpiece (100) in order to counteract the distortion.

3. The method according to any one of the preceding claims, further comprising the step of: detecting a workpiece geometry, wherein the secondary modification power (P2,mod) is adjusted based on the detected workpiece geometry.

4. The method according to claim 3, wherein the detection of the workpiece geometry takes place before and / or after the laser deposition welding of the first workpiece side (120) in the initial configuration.

5. The method according to any one of the preceding claims, further comprising the step of: detecting a temperature of the workpiece, wherein the secondary modification power (P2,mod) is adjusted based on the detected temperature.

6. Method according to one of the preceding claims, wherein the secondary modification power (P2,mod) varies over a temporal process course in order to compensate for a non-linear distortion.

7. The method according to claim 6, wherein the workpiece (100) is substantially rotationally symmetrical and the secondary modification power (P2,mod) increases with increasing radial distance from the rotation axis of the workpiece (100).

8. Method according to one of the preceding claims, wherein the primary laser beam (51) is operated with the same primary initial power (P1) in the initial configuration and the modified configuration.

9. The method according to any one of claims 1 to 7, wherein a total laser power of the primary laser beam (51) and the secondary laser beam (52) remains the same in the initial configuration and the modified configuration, so that a power of the primary laser beam (51) in the modified configuration changes compared to the initial configuration by an amount equal to the difference between the secondary initial power (P2) and the secondary modification power (P2,mod).

10. Method according to one of the preceding claims, wherein the primary laser beam (51) and the secondary laser beam (52) originate from the same laser source, wherein a power distribution between the primary laser beam (51) and the secondary laser beam (52) is continuously adjustable via a motorized adjustment unit, in particular a motorized wedge switch.

11. Method according to one of the preceding claims, wherein the workpiece (100) is rotated about a transverse axis (180) orthogonal to a rotation axis (170) of the workpiece (100) after the laser deposition welding of the first workpiece side (120) in the initial configuration in order to carry out the laser deposition welding of the second workpiece side (130) in the modified configuration.

12. The method according to any one of the preceding claims, wherein a first bonding layer is applied by means of laser deposition welding of the first workpiece side (120) in the initial configuration; and a second bonding layer is applied by means of laser deposition welding of the second workpiece side (130) in the modified configuration; further comprising the steps: Laser deposition welding of the first workpiece side (120) in a wear configuration in which the primary laser beam (51) is operated with a primary wear power and the secondary laser beam (52) is operated with a secondary sealing power in order to apply a first wear protection layer to the first adhesion layer; Laser deposition welding of the second workpiece side (130) in a modified wear configuration in which the secondary laser beam (52) is operated at a secondary wear modification power in order to apply a second wear protection layer to the second adhesion layer.

13. A system for distortion-compensating laser deposition welding of a functional layer (110) onto a workpiece (100), comprising: a first beam nozzle (1100) provided and configured to process a first workpiece side (120) by means of a primary laser beam with a primary initial power (P1) and a secondary laser beam with a secondary initial power (P2) in order to apply a first adhesion layer; a second beam nozzle (1200) provided and configured to process a second workpiece side (130) opposite the first workpiece side (120) by means of a primary laser beam and a secondary laser beam with a secondary modification power different from the secondary initial power (P2) in order to apply a second adhesion layer;a third beam nozzle (1300) provided and configured to process the first workpiece side (120) by means of a primary laser beam and a secondary laser beam with a secondary wear power different from the secondary modification power, in order to apply a first wear protection layer; a fourth beam nozzle (1400) provided and configured to process the second workpiece side (130) by means of a primary laser beam and a secondary laser beam with a secondary wear modification power different from the secondary wear power, in order to apply a second wear protection layer; wherein the four beam nozzles (1100, 1200, 1300, 1400) are connected to one another via a production line (1500) in order to enable distortion-compensating laser deposition welding.

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