Method for the additive manufacturing of a three-dimensional component in a layering device, and layering device

Abstract

The invention relates to a method for the additive manufacturing of a three-dimensional component in a layering device which comprises a construction space and a processing beam generating device (20). The method has the steps of: providing at least one material (28) on a processing plane (32) in the construction space in order to produce the component (30) layer by layer from the at least one material (28); emitting a processing beam (24) from the processing beam generating device (20) onto the processing plane (32) in the construction space and forming a freely selectable irradiance profile (10) on the processing plane (32) by means of the processing beam (24) in such a way that the irradiance profile (10) has at least one functional region (12) and / or at least one melting region (14). The value of the irradiance of the irradiance profile (10) in the melting region (14) is greater than an irradiance limit value which corresponds to the melting temperature of the material (28), and the value of the irradiance in the functional region (12) is less than the irradiance limit value and is sufficient to change a material property of the component (30).

Description

[0001] Method for the additive manufacturing of a three-dimensional component in a layered construction device and layered construction device

[0002] Description

[0003] The invention relates to a method for the additive production of a three-dimensional component in a layered construction device according to the preamble of claim 1. Furthermore, the invention relates to a layered construction device.

[0004] In so-called additive or generative manufacturing processes (so-called rapid manufacturing or rapid prototyping processes), a component section or a complete component, which could be, for example, a component of a turbomachine or an aircraft engine, is built up layer by layer. Due to the near-net-shape component production, a PBF-LB / M process ("Laser-Based Powder Bed Fusion of Metals") is a widely used method in industry for producing functional components with highly complex geometries. Complex geometries are realized by melting or sintering powder layers layer by layer. In aviation, metal powders are preferred, which combine low material density with high material performance to meet the requirements of lightweight construction concepts.This includes, for example, the alloy Ti-6A1-4V, which exhibits high strength and elongation at break with a low density. However, titanium alloys are known to develop high residual stresses. The very high heating and cooling rates characteristic of the process are provoked by the high energy density introduced into the material. The high energy input via a processing beam (e.g., a laser beam or electron beam; hereinafter referred to collectively as the "processing beam") also leads to high thermal gradients, which promote the occurrence of residual stresses. The residual stress-driven geometric component distortion can lead to coater collisions, process interruptions, or component rejection. Furthermore, residual stresses remaining in the material can shorten the component's service life.Depending on the material, it is often not possible to produce a crack-free component or a component without distortion due to process-related residual stresses. Especially with titanium alloys, this can lead to the component tearing off the build platform, for example. However, a reduction in residual stresses through multiple exposures can have disadvantages in mechanical behavior due to produced defects. Especially when multiple exposures are carried out with constant process parameters, in many cases no significant reduction in residual stresses can be observed. The time interval between neighboring tracks and layers before a new exposure can also play a role in controlling the heat balance. The development of residual stresses can be controlled by the cooling time available to the material and the prevailing thermal gradient.The mechanism during heat treatment is based on stress relaxation, which can reduce residual stresses. However, subsequent heat treatment cannot prevent, for example, distortion during the process, crack formation, or detachment of the component from the component platform. There is also the method of distortion compensation, in which a geometric compensation for the distortion is already stored in the CAD (computer-aided design) model. However, this compensation does not reduce residual stresses and merely influences the dimensional accuracy of the component.

[0005] A trend in additive manufacturing is moving beyond prototype construction to functional components. This revolution is being made possible by ever-increasing productivity through process optimization. The tight geometric tolerance ranges of functional components and the high demands on component quality pose manufacturing challenges. A stable process is essential for producing reproducible series components, especially under aviation conditions. To meet the industrial trend of increasing component sizes, it is necessary to consider thermal behavior, especially for complex PBF-LB / M components made of H-6A1-4V. Thermal distortion and the control of residual stresses play a key role in meeting geometric requirements and the associated process stability.The residual stresses resulting from the high thermal gradient can also limit the structural geometric freedom of the components.

[0006] External methods for eliminating residual stresses, such as global preheating or a subsequent heat treatment process for stress relaxation, are often uneconomical, especially if, for example, the entire build space must be kept at very high temperatures such as 1000 °C for several days. For example, the document DE 10 2019 003 528 A1 discloses additive manufacturing for metals using a fiber array laser source and adaptive multiple beam shaping. This system uses a scalable array of individually controllable laser beams generated by a fiber array system to process materials into an object. The adaptive control of individual beams can include beam power, focal length, center of gravity position, scan orientation, amplitude and frequency, piston phase, and polarization states of individual beams.However, controlling multiple laser beams is complex and requires a lot of space. Furthermore, a sufficient distance from the material must be maintained to ensure that all individual laser beams can reach the material.

[0007] Furthermore, for example, document EP 4 076 804 A1 discloses a method for additive manufacturing by powder bed fusion, in which an object is built up in a layer-by-layer manner, and for each layer of a plurality of successively molten layers, melting a material of the layer by irradiating the layer with one or more energy beams at a first time using a first set of irradiation parameters, allowing the molten material to solidify to define a fused region of the layer, and reheating the fused region by irradiating the layer at a subsequent time with one or more of the energy beams using a second set of irradiation parameters, wherein the first set of irradiation parameters comprises at least one irradiation parameter that is different from the second set of irradiation parameters.However, melting with a second laser beam is complex because two optics have to be provided, and remelting with the same laser beam at a later time is time-consuming because the layer has to be scanned twice.

[0008] It is therefore an object of the invention to provide an additive manufacturing process that offers a simple way to flexibly adapt an exposure strategy, that reduces the equipment required for an additive manufacturing process and at the same time is capable of providing high-quality components with minimal residual stresses.

[0009] This object is achieved by providing a method for the additive production of a three-dimensional component (30) in a layered construction device which comprises a construction space and a processing beam generation device (20), with the steps: providing at least one material (28) in a processing plane (32) in the construction space for layer-by-layer production of the component (30) from the at least one material (28);

[0010] Emitting a processing beam (24) from the processing beam generating device (20) onto the processing plane (32) in the construction space and

[0011] Forming a freely selectable irradiance profile (10) in the processing plane (32) by the processing beam (24) such that the irradiance profile (10) has at least one functional region (12) and / or at least one melting region (14), wherein a value of an irradiance of the irradiance profile (10) in the

[0012] Melting region (14) is greater than an irradiance limit value which corresponds to a melting temperature of the at least one material (28), and the value of an irradiance in the functional region (12) is less than the irradiance limit value and is sufficient to change a material property of the component (30) during the generation of the melt track (SdT) at least in some regions - next to the track just generated, the already solidified neighboring track and / or the neighboring tracks already generated or the melt track yet to be generated and / or next to a melt track not just generated in the direct powder environment.

[0013] According to the invention, when the material properties of a component are changed, the powder is also counted, which is preheated for the next melt track to be created in order to manipulate the thermal gradient. The invention is based on the idea that a processing beam is suitably adapted to provide an irradiance profile in a processing plane within the build space, which can have multiple regions. These regions do not have to be contiguous and can comprise several spatially separated regions. The irradiance profile can be dynamically adjusted while scanning the component or traversing the component's layer structure. The formation of the irradiance profile can be realized, for example, using a beam-shaping device.

[0014] This is also due to the fact that a laser beam profile, its intensity, and the resulting weld characteristics can influence component properties. Conventional PBF-LB / M manufacturing is generally based on the use of Gaussian beam shapes. Intervention in the development of residual stress behavior using a Gaussian profile is limited due to the physical effects that occur. The peak intensity in the center of the Gaussian laser beam allows only limited control of a thermal gradient and the resulting residual stress behavior. The lack of flexibility in the energy distribution of the Gaussian laser beam can also limit the weld seam profile that can be created, which can influence microstructure development and resulting residual stresses. For the required economical production, the Gaussian beam diameter cannot be arbitrarily increased on conventional machines.

[0015] According to one embodiment of the invention, the invention provides a method for the additive production of a three-dimensional component in a layered construction device comprising a build space and a processing beam generation device. The method comprises a step of providing at least one material in a processing plane in the build space for layer-by-layer production of the component from the at least one material. Furthermore, the method comprises radiating a processing beam from the processing beam generation device onto the processing plane in the build space and forming a freely selectable irradiance profile in the processing plane by the processing beam such that the irradiance profile has at least one functional region and / or at least one melting region.In this case, a value of an irradiance of the irradiance profile in the melting region is greater than an irradiance limit value corresponding to a melting temperature of the at least one material, and the value of an irradiance in the functional region is smaller than the irradiance limit value and is sufficient to change a material property of the component.

[0016] In other words, the invention provides a method for the additive production of a three-dimensional component or a three-dimensional body in a layered construction device having a construction space for the layer-by-layer production or layer-by-layer construction of the component from a material, in particular a powdered material, which is provided in the construction space in a processing plane. In this case, the material can be locally melted and solidified layer by layer to form a layer of the component. A mostly powdered material can be applied layer by layer in the construction space, i.e., in a region of a construction field or a construction and joining zone on a platform, to form a powder layer.The material is provided in the processing plane, for example, by applying a layer of powder with a coating tool in the processing plane, or after partially melting the layer and lowering the component by a layer thickness, a new layer of powder is applied flatly, for example with a coating device. Metallic components, in particular, can be easily manufactured using laser beam melting or laser beam sintering processes. An electron beam can also be used instead of a laser beam. Laser beams and electron beams are collectively referred to herein as processing beams. Furthermore, the material can be a multi-material, a mixture of several materials, or can be modified within the processing plane.This may have an influence on the melting temperature, which can be taken into account, for example, by dynamically adjusting the irradiance profile, the irradiance and / or other parameters.

[0017] After the powdered material has been applied, the material is melted by the processing beam in the processing plane along a path of exposure positions, which is followed by the processing beam, in order to create a component layer. This means that the material can be locally melted and solidified by supplying energy to the material in the build space using the processing beam, whereby the material can melt or sinter and form a component layer. It should be noted that both the material and the component are locally melted by the processing beam and can thus bond together. The depth of the melting zone is only limited by the processing beam power and can have a variety of layer thicknesses, for example, one, three or five layer thicknesses depending on the layer thickness, to name just a few examples.Generating the path of exposure positions from the component's layer information can be part of an exposure strategy or scanning strategy, meaning the processing beam can be controlled depending on layer information for the respective component layer to be produced. The term exposure strategy or scanning strategy refers to the conversion of component layer information into the path of exposure positions that the processing beam follows to create the component's layer. The layer information can be generated from a 3D CAD body of the component, and the 3D CAD body can be divided into individual component layers. After the molten material has solidified, the build platform can be lowered layer by layer by a predefined layer thickness.The above steps can then be repeated until the desired component area or the entire component is finally completed. The component area or component itself can generally be manufactured on a build platform, on a previously produced part of the component or component area, or on a support structure. The advantages of this additive manufacturing process lie in the ability to produce very complex component geometries with cavities and / or undercuts within a single process.

[0018] The term "freely selectable irradiance profile" can mean that the irradiance profile can be shaped, for example, by a beam-shaping device, that the irradiance profile can be non-Gaussian, can have multiple regions, can be dynamically adjusted, cannot represent a composition of multiple Gaussian spots (but can be represented within the irradiance profile) and / or can be easily adjusted, for example, by means of a control device.Furthermore, the term can mean that the irradiance profile in a plan view of the processing plane can have a non-Gaussian shape and can, for example, be elliptical, star-shaped, rectangular, have a ramp profile, or two or more elliptical shapes next to each other, so that the irradiance profile in plan view, for example, has a wave-like shape. This means, for example, that the irradiance profile has a taper in the center of the irradiance profile. Furthermore, the irradiance profile can have both a symmetrical and an asymmetrical shape.

[0019] Since traversing the path from exposure positions with the positioning device can be time-consuming, additive manufacturing allows for parallel production of multiple parts side by side for efficiency reasons. A complete production run can potentially take several days or even weeks.

[0020] Additive manufacturing offers simple ways to flexibly adapt scanning strategies. A scan pattern and scan vectors play a key role in this. One method for reducing residual stresses is, for example, an angular rotation of the scan vectors per layer. Lower residual stresses than in a case without rotation can be generated by a rotation of 45°, 67°, or 90°, to name just a few examples. However, this is often not sufficient to completely prevent cracking and component distortion. Rotating the scan vectors can serve to compensate for residual stresses in different directions. In addition, the scanning strategy can reduce residual stresses in the component by manipulating the microstructure and texture. A fine microstructure with a low texture can be achieved through angular rotation and often results in a reduction of residual stresses.

[0021] Furthermore, the length of the scan vectors can influence residual stresses. Using short scan vectors can be advantageous for minimizing longitudinal stress in a seam and reducing thermal gradients. The dimensions of an area to be scanned can also influence residual stresses. For example, flat areas can maintain higher temperatures longer than areas with a smaller surface area, which can also influence thermal gradients. This behavior shows a geometry dependence. Unidirectional and bidirectional strategies are also possible, with the latter producing lower stresses in the component.

[0022] The layer-building device further comprises a processing beam generating device configured to emit at least one processing beam, and preferably only a single processing beam, into the build space onto the processing plane and to form an irradiance profile or intensity profile of the processing beam in the processing plane such that the irradiance profile has at least one functional region and / or at least one melting region, which also includes a split and bundled beam, which is considered a processing beam. The use of only one processing beam reduces the complexity of the layer-building device compared to the use of multiple processing beams and enables a reduction in costs for the layer-building device.Optionally, the processing beam generating device can also comprise several processing beams or a division of the processing beam into several processing beams.

[0023] In a particularly preferred embodiment, the irradiance profile can have at least two melting ranges, at least three melting ranges, at least four melting ranges, or a plurality of melting ranges. This allows processes such as remelting, deeper melting, superficial melting, and the like to be implemented. Furthermore, the irradiance profile can have at least two functional ranges, at least three functional ranges, at least four functional ranges, or at least five functional ranges. This allows complex processes such as stress relieving, solution annealing, preheating, phase precipitation, hardening, and / or material changes such as a change in grain size, texture, nucleation, healing of defects such as created cavities (pore bonding defects), and the like to be implemented, for example to reduce residual stresses.This allows improvements in material properties such as tensile, creep, strength, or cyclic properties to be achieved. The functional area can be located either within the track to be created or adjacent to it. This means that neighboring tracks that have already solidified can be heat-treated by the functional area while the new melt track is being created in the melting area. Preheating and postheating profiles can also be implemented, which can be positioned on all sides of the melting area. For example, powder adjacent to the melt track can also be preheated. Preheating the powder during the creation of the melt track can homogenize the thermal gradient and, for example, reduce residual stresses.When the already solidified neighboring track is reheated or melted, defects such as pores or cracks can be healed and material properties in the form of phase precipitation or grain size and orientation can be changed, which influence the mechanical properties of the component.

[0024] In the melting range, an irradiance value (or light output, energy output) of the irradiance profile is greater than an irradiance limit value corresponding to the melting temperature of the material. This means that the material can be irradiated with an irradiance sufficient to melt the material and / or the component. The irradiance can depend on the component geometry, scanning speed, cooling rate, material properties, thermal conductivity of the material, existing component structures or support structures, surface roughness, the metal alloy used, powder particle size, and many other factors, which are listed below as examples.Furthermore, the irradiance can be dynamically adjusted to a track width, a light absorption capacity of the material or component, a layer thickness, a processing beam power, a scanning speed, a track pitch, a scanning direction (i.e., an exposure position travel direction), and / or a pulse rate of the processing beam. Adjustment can also be implemented by means of in-situ observation such as a measurement or image capture, a temperature measurement, a thermal radiation measurement, a detection of defects, holes, and / or bubbles, as well as by means of an evaluation by a control device, which can subsequently dynamically adjust the irradiance to bring a measured value to a target value.In the functional range, the irradiance value is lower than the irradiance limit, so that the material or component is only partially melted in order to bring the desired temperature into deeper layers without the newly created structure being destroyed by the subsequent layer or not being melted at all. However, it is sufficiently large to change or influence a material property of the component. Furthermore, in the functional range, irradiation can delay solidification of the molten material by slowing the cooling rate, for example through reheating. This means that a material change or component change such as phase precipitation, a reduction in residual stress, a change in strength or a change in the structure can be achieved.Annealing processes, stress relief annealing, solution annealing, and even a slowed cooling rate, etc., can also be achieved. For example, it is possible to heat the material to a first temperature or to hold it at a first temperature for an extended period before the material / component is heated to the melting temperature in the melting range. Furthermore, the component can be cooled slowly and in a targeted manner by radiating sufficient energy into the functional area to slowly and controlledly lower the temperature. This can reduce residual stresses, which, particularly with large components, thickness changes, or other geometric factors, can become so great that the component can, for example, unintentionally detach from the build platform, which can lead to coater collisions and / or component quality losses.Therefore, it is especially important for these components that the functional area is available that can achieve a reduction in residual stresses.

[0025] With the invention, residual stresses can be reduced by a suitable processing beam profile with different irradiances. Selecting and / or adjusting suitable apertures, field mappers, beam integrators, acousto-optical beam shaping, and / or a liquid crystal element allows a free choice of the irradiance profile and / or its intensity distribution. The knowledge that subsequent heat treatment can relieve residual stresses is to be integrated into just one processing beam. Unlike subsequent heat treatment, which may require the application of high temperatures of, for example, 1000°C for several hours or days, component distortion and crack formation are suppressed during additive manufacturing. For this purpose, the processing beam can be generated in the generation device and directed to the beam shaping device.The beam-shaping device can change, alter, or modify the incoming processing beam by means of beam shaping in order to shape the outgoing processing beam with regard to its thermal and geometric profile. Beam shaping may, for example, require that the processing beam be expanded beforehand. The beam shaping of an incoming beam profile, for example a Gaussian beam profile of the processing beam, into a desired irradiance profile can be performed both statically and dynamically.

[0026] A possible example of beam shaping involves the use of apertures (static beam shaping) and / or spatial light modulators. These can be placed in the beam path of the processing beam and can be designed to allow only a portion of the radiation to pass through. Radiation absorbed or reflected by an aperture cannot be used to irradiate the component. Therefore, the use of apertures can result in power losses at the aperture.

[0027] Another example of static beam shaping involves the use of diffractive or refractive elements (so-called field mappers). Refractive beam shaping is based on the diffraction of beams through the use of optics such as prisms and / or optical gratings. Diffractive beam shaping can utilize refraction effects to influence the processing beam. For example, specific micro- or nanostructures can be created in a substrate through an etching process, and wavelength-dependent diffractive beam shaping can be controlled and adjusted, for example, through the periodicity of the micro- or nanostructures. When using diffractive elements, only minimal power losses occur, and the complexity of the beam shaping setup can be low, since only one element may need to be provided to achieve diffractive beam shaping.This type of beam transformation can be particularly suitable for single-mode beam sources, for example, and any desired irradiance profiles can be generated.

[0028] Another example of beam shaping involves the use of beam integrators or homogenizers. Lens arrays can be used, for example, to split the input beam into multiple beams, which can then be superimposed in the processing plane using additional lenses and focusing elements. Individual apertures in the lens arrays can generate diffraction patterns that can determine the output beam. In contrast to the beam shaping techniques mentioned above, beam integrators can be used for multi-mode beams. When using homogenizers, fluctuations in the beam intensity of the processing beam can affect the irradiance profile.

[0029] Another example of beam shaping includes acousto-optical beam shaping. This beam shaping can ensure high deflection switching rates while simultaneously being suitable for use with high laser powers. For example, piezoelectric elements are used to generate bulk acoustic waves in an optical material, and the processing beam can be diffracted by the sound field generated by the bulk acoustic waves as it passes through the optical material. Acousto-optical beam shaping has a lower diffraction efficiency than the beam shaping methods mentioned above, which can be compensated for, for example, by extending the path length of the processing beam in the optical material or by increasing the path length of the processing beam between the beam shaping device and the processing plane.However, an advantage of acousto-optical beamforming is high switching rates, which can cover a range from 1 kHz to 100 kHz, to 200 kHz, or even to 1 MHz, with which the processing beam can be controlled.

[0030] Another example of beam shaping includes beam shaping using a liquid crystal element or liquid crystal modulator. The liquid crystal element can be used, for example, in reflection or transmission. Optionally, the liquid crystal element can be electrically switchable using attached electrodes. The liquid crystals can cause a phase delay and / or a polarization rotation of the light reflected or transmitted by the liquid crystal element, which can be used, for example, to form a phase front or wave front that can lead to a predetermined irradiance profile in the processing plane.

[0031] The invention has the advantage that sequential multiple exposure of the component or the processing plane can be avoided by adjusting the irradiance profile such that a melting process and upstream and / or downstream heat treatments, which may also affect the non-melting track, such as powder or solidified adjacent regions, can be performed in a single pass. At the same time, the invention allows further heat treatments of the material or the component to be performed using only one processing beam and only one processing beam path, thus reducing the complexity of the layer-building device.The processing beam is provided, which can be positioned on the processing plane in the build space by means of the positioning device, and whose irradiance profile can be further adjusted statically or dynamically using acousto-optical modulators, apertures, spatial light modulators, liquid crystal modulators, and the like. Furthermore, the irradiance profile can also be modulated using electronically controllable lenses, polarization optics, and the like. This can also reduce overall complexity by reducing the effort required to adjust the processing beam, since only one processing beam needs to be adjusted.

[0032] Furthermore, the invention has the advantage that a particularly wide variety of products can be manufactured additively. Furthermore, alloys that are difficult to weld, alloys that require subsequent heat treatment to achieve the desired mechanical properties, or alloys that are prone to thermal distortion and cracking can be used or processed. Furthermore, plastics can also be used or processed particularly easily as a material.

[0033] Furthermore, the process is not limited to the use of a laser beam, and instead of laser beam melting, electron beam melting using an electron gun can be used. With an electron beam, an irradiance profile as described above can be achieved using electronic or magnetic fields. If a special atmosphere such as a pre-vacuum or high vacuum is required, this can be easily achieved by sealing the build chamber and pumping out the build chamber volume.

[0034] Furthermore, the invention offers the advantage that global preheating of the entire build space by means of a build platform heater to achieve a globally lower thermal gradient can be avoided, since such global preheating of the entire build space to a high temperature in the range of, for example, 500 °C to 1000 °C can lead to aging of the powdered material, i.e., to material aging due to oxidation and / or phase precipitation of metallic phases. The invention preheats only locally in adjacent areas, thus preserving the aging process of the remaining powder in the build space that is not part of the component. This can impair the reusability of the powdered material.Since in the invention the material and the component are only melted locally in the melting area and heat treatment is only carried out in the functional area, the invention offers the advantage of better reusability of the powdered material and thus a further cost reduction and a positive environmental aspect.

[0035] The invention also has further advantageous embodiments which provide further advantages in addition to the advantages mentioned above.

[0036] According to a further advantageous embodiment, the layered construction device comprises a beam-shaping device, only a single processing beam is generated in the processing beam generation device, and its irradiance profile is shaped in the beam-shaping device. In this case, a single processing beam can be generated in the processing beam generation device, which, for example, when using beam integrators, is split into several partial beams, which are subsequently recombined. This results in a particularly simple geometry and reduced complexity of the structure, thus allowing a further cost reduction.

[0037] According to a further advantageous embodiment, the irradiance profile is positioned by means of a positioning device along a path of exposure positions in order to form a component layer. In this case, it is possible to use a positioning device that is configured to two-dimensionally position the processing beam for layer-by-layer construction of the component in the build space along a path of exposure positions. This can be achieved, for example, using a mirror galvanometer (also known as a galvo scanner). Alternatively, this can mean that a powder bed positioning device is provided that positions the powder bed and the component relative to the processing beam.

[0038] According to a further advantageous embodiment, it is provided that the functional region has a predetermined pose relative to the melting region, and the processing beam generating device, the beam shaping device (22), and the positioning device (26) cooperate to adapt the predetermined pose depending on the path of exposure positions. Here, a pose is synonymous with a predetermined location and orientation. The pose of the functional region relative to the melting region depends, for example, on a scanning direction, whether the irradiation is carried out at the edge of the component, and is dependent on the scanning speed and the processing beam power. In this case, a thermal behavior of the component and its support structures can be modulated, for example, by simulation, and the pose between the functional region and the melting region can be adapted depending on a simulation result.It should also be noted that a scanning direction can be rotated from layer to layer by, for example, 30°, 67° or 90° to further reduce residual stresses.

[0039] According to a further advantageous embodiment, the beam shaping device is configured to dynamically adapt the irradiance profile as a function of a component geometry, a heating rate, a cooling rate, a light absorption capacity, a layer thickness, a processing beam power, a scanning speed, a track pitch, a volume energy density, a scanning direction, and / or a pulse rate of the processing beam. Furthermore, these parameters can be changed for each layer or within a component and can be static for each layer. In this case, a processing beam diameter can range from a few 10 pm up to 1 mm or more in large spots. The irradiance profile can be defined by simulation and can be adapted to a thermal behavior, a component geometry, and the desired microstructuring in order to achieve predetermined mechanical properties.For example, an edge of the component can be irradiated with a different irradiance than a central region of the component. For this purpose, the beam-shaping device advantageously comprises components with switching times of a few microseconds to milliseconds. These components can be, for example, apertures, field mappers, beam integrators, and / or acousto-optical beam-shaping devices, which allow a free selection of the processing beam shape and its intensity distribution. This enables a particularly simple implementation of the invention and provides further cost reductions.

[0040] According to a further advantageous embodiment, the beam-shaping device / positioning device forms the irradiance profile of the processing beam by means of a diaphragm, by means of a field mapper, by means of beam integrators, by means of an acousto-optical deflection element, in particular with a switching rate in the range of one kilohertz to one megahertz and preferably up to 200 kilohertz or even more preferably up to 100 kilohertz, and / or by means of a liquid crystal element. Rapid positioning with an acousto-optical deflection element makes it possible, for example, to position the processing beam within an irradiation field so quickly that the melting region and the functional regions can be reached.Since the thermal behavior of the material or component reacts on a slower timescale than the timescale for positioning the laser beam, the rapid positioning of the processing beam is quasi-static for the component or material. Alternatively, liquid crystals or a liquid crystal element can be used to position the laser beam. This embodiment has the advantage of allowing a particularly simple implementation of the inventive concept.

[0041] According to a further advantageous embodiment, the irradiance value in the functional area is set such that a homogenized or specifically controlled thermal gradient, predetermined phase precipitations and / or phase resolutions, a heat treatment, a texture change and / or a lattice equalization or lattice distortion, in particular for the targeted control of material properties, reduction of residual stresses, microstructure adaptation, defect minimization and / or defect healing in the irradiated component, can be generated. For example, heat treatments for generating predetermined mechanical properties or for reducing residual stresses can be implemented using this embodiment.For example, delayed solidification processes or homogenized thermal gradients through irradiation in the functional area can achieve a reduction in residual stresses, simulate casting or forging processes, achieve stress relief annealing and / or phase precipitation, and / or suppress or heal gas voids or fusion defects. Phase precipitation or phase dissolution may be desirable because they can increase strength. This allows for easy implementation of intended heat treatments and, for example, avoids an expensive and time-consuming HIP (Hot Isostatic Pressure) process.

[0042] According to a further advantageous embodiment, the construction space can be heated by means of a heating element. In other words, an additional heating element can be installed in the construction space, which can be used, for example, for preheating to 80 °C (degrees Celsius) for powder drying. Further exemplary embodiments can be found in the drawings and the following detailed description, which are not intended to limit the scope of the invention.

[0043] Here we show:

[0044] Fig. 1 is a schematic representation of an irradiance profile;

[0045] Fig. 2 shows a further schematic representation of an irradiance profile;

[0046] Fig. 3 shows a further schematic representation of an irradiance profile;

[0047] Fig. 4 shows a further schematic representation of an irradiance profile;

[0048] Fig. 5 shows a further schematic representation of an irradiance profile;

[0049] Fig. 6 is a further schematic representation of an irradiance profile and a heat treatment to achieve special material properties; and

[0050] Fig. 7 is a schematic representation of an additive layered construction device.

[0051] Fig. 1 shows an irradiance profile 10 as a contour plot, wherein the irradiance profile 10 is moved in the direction 58 in the processing plane 32. The scanning direction 58 is also shown. Here, the irradiance profile 10 has a first region (melting region 14) in which an irradiance range with included irradiance E1 is achieved, as well as a second region (functional region 12, which can be divided into the functional region 1, 12.1 and the functional region 2, 12.2) in which an irradiance range E2 or two different irradiance ranges E2 and E3 are achieved. The lower part of Fig. 1 shows a sectional view of the irradiance profile 10 along a line AA, wherein a location x along the cutting direction is plotted as the x-axis. The irradiance E is shown as a value on a vertical axis.In scenario 1, the irradiance profile 10 is moved along a path 58, with region 14 containing an irradiance range that reaches an irradiance E1, the level of which is above the melting temperature. Furthermore, the irradiance profile 10 has two functional regions 12.1 and 12.2, with functional region 12.1 having an irradiance E2 less than E1 and thus heat-treating at least one solidified neighboring track, and functional region 12.2, which, for example, also contains the irradiance E2, with functional region 12.2 also being able to have an irradiance E3 and not necessarily matching 12.1. Here, functional region 12.2 has the task of locally preheating powder of the neighboring track yet to be produced in order to change the thermal gradient and manipulate solidification conditions, which also influence the mechanical properties of the track.

[0052] A second scenario can be executed by rotating the beam profile by 90°. The irradiance profile 10 is then scanned or moved along the path from irradiation positions over the material 28 or the component 30, so that the irradiance profile 10 reaches a predetermined point on the path first with the point x0 of the irradiance profile 10, whereby this scenario is applied when the scanning direction (looking at the figure) points to the right, which is also covered by the invention. Also encompassed by the invention is a beam profile rotated by 90° (not separately shown here). At the point x0, the irradiance begins to rise and increases to a value E2 at the point x1. At the point x2, the irradiance increases further to reach the value E1 at x3.The value El is dimensioned such that it lies above an irradiance E0 that is sufficient to melt the material 28 or the component 30. The irradiance El is maintained up to point x4, from which point the irradiance drops to the value E2 at x5. This ensures that the component solidifies more slowly than without irradiation or, due to the delayed cooling, is kept liquid for longer. The range from x5 to x6 can be referred to as the post-heating range. Here, a heat treatment is carried out for a predetermined time that corresponds to the length x5 to x6 divided by the scanning speed. At point x6, the irradiance drops to the value 0 at x7. Thus, preheating of the material 28 can be achieved in the range x1 to x2, melting of the material can be achieved in the range x3 to x4, and post-heating of the component 30 can be achieved in the range x5 to x6.

[0053] In other words, the front part of the irradiance profile 10 preheats the material 28, the middle of the irradiance profile 10 effects the actual melting process, and in the rear part of the irradiance profile 10, with lower irradiance, the temperature of the component 30 is reduced more slowly than without irradiation, and the thermal gradient is controlled in a targeted manner. The figure shows, as an example, the freshly created track 60 and the already solidified neighboring tracks 61 from the processed powder 59. Fig. 2 shows a modification of the aforementioned irradiance profile 10 from Fig. 1. In this case, the post-heating region is essentially omitted, and only preheating with an irradiance E2 in the functional region 12 and melting of the material 28 or the component 30 in the melting region 14 take place at an irradiance E1 that is greater than the irradiance limit value E0.Thus, melting of the material 28 or the component 30 is only achieved in the area xl1 to xl2. The irradiance profile 10 can be moved along the direction 16 over the component 30 or across the processing plane 32 by means of the positioning device. For example, however, the irradiance profile 10 can also be moved in a direction perpendicular to the direction 16 by means of the positioning device in order to ensure that, for example, when the component 30 is scanned line by line with the irradiance profile 10, the functional area 12 irradiates a predetermined position in the processing plane, for example multiple times and / or with a time delay. In other words, the irradiance profile 10 is freely selectable and can be moved in any direction over the component 30.

[0054] For example, a front functional area 12 of the irradiance profile (i.e., the part of the irradiance profile 10 that reaches an irradiation position first) can include preheating similar to continuous preheating of the component 30 or the material 28 by a build platform heater (although without the disadvantages). The preheating process is integrated into the processing beam 24. The front part of the processing beam 24 locally preheats the material 28 to a temperature below the melting temperature of the material 28. The actual melting process takes place in the rear part of the irradiance profile 10 (i.e., the part of the irradiance profile 10 that reaches an irradiation position last). This homogenizes the thermal gradient overall, resulting in lower residual stresses.

[0055] Fig. 3 shows a further example of a modification of the aforementioned irradiance profile 10 from Fig. 1. Here, the irradiance profile is divided into a melting region 14 and a functional region 12, in which the functional region 12 reaches an irradiance E2, which thus has a functional effect on the molten and solidifying component 30. For example, phase precipitation of a particularly preferred material phase can be achieved. The irradiance E2 depends on the travel speed of the irradiance profile 10, a track width, a processing beam intensity, and other influencing factors described above. The figure shows, as an example, the freshly generated track 60 and the already solidified neighboring tracks 61 from the processed powder 59.

[0056] If the beam shape is rotated 90° counterclockwise, for example, a front melting region 14 of the irradiance profile 10 (i.e., the part of the irradiance profile 10 that reaches an irradiation position first) can have an intensity that melts the material 28. In the rear part of the irradiance profile 10 (i.e., the part of the irradiance profile 10 that reaches an irradiation position last), the irradiance can decrease, resulting in a homogenized thermal gradient rather than immediate cooling. The functional region 12 of the processing beam 24 can at least correspond to the melting region or even be larger than the melting region.The irradiation intensity can be adjusted so that heat treatments of the component 30 can be replaced and precipitations in the structure can be controlled, which can influence the mechanical properties of the component 30.

[0057] Fig. 4 further shows another possible irradiance profile 10 with three melting regions 14 and one functional region 12. By dividing the melting region into three melting regions 14, particularly advantageous material processing and a particularly significant reduction in residual stress can be achieved. The irradiance is selected such that a homogeneous, more homogeneous, and / or homogenized temperature field is created compared to the Gaussian processing beam profile. Fig. 4 shows one possible irradiance profile 10.

[0058] Fig. 5 further shows a schematic representation of an irradiance profile 10 which is divided into three separate regions. In the right-hand sub-region, for example, particularly deep melting can be achieved. In the middle region, an annular profile can be used to surround a functional region 12 by a melting region 14. In the left-hand sub-region, a functional region 12 can also be surrounded by an irregularly shaped melting region 14. This can lead to particularly advantageous material processing. Fig. 6 illustrates a further example of an irradiance profile 10, wherein a desired thermal process for material processing serves as a template. In the upper region of Fig. 6, for example, a heat treatment profile is shown, wherein a temperature of a component 30 (vertical axis) is shown over a time course t (horizontal axis).In a first region 41, for example, stress relief annealing of the material can be carried out. In a second region 42, melting can be carried out in which a melting temperature of the material is exceeded. Alternatively, for example, a phase transformation temperature can be deliberately exceeded in the second region 42 so that a certain phase transformation can be achieved. For example, by exceeding the delta solvus temperature in Inconel 718, a delta phase can be dissolved in the component above this temperature. In a region 43, solution annealing can be carried out. In a region 44, a first aging stage and subsequently a second aging stage can be carried out. This temperature profile can be implemented in an irradiance profile 10 as below, which is shown in the lower part of Fig. 6.A first region 51 can be configured to effect stress relief annealing. A second region 52 can be configured to effect melting. Solution annealing can be performed in a third region 53, a first aging stage in a fourth region 54, and a second aging stage in a fifth region 55. A region 57 can be configured to preheat or postheat a component 30 to a predetermined temperature. Regions 51, 53, 54, 55, and 57 correspond to functional regions 12, with different irradiation intensities being configured in these regions, and region 52 corresponds to the melting region 14.

[0059] Fig. 7 shows a schematic structure of an additive manufacturing device in one exemplary embodiment. A mostly powdery material 28 is provided on a platform 34 in a build space (i.e. in an area of ​​a build field or a build and joining zone), wherein the platform 34 can be provided in a trough 36 in order to hold the material 28 on the platform 34. The material 28 can be applied to the platform 34 in layers to form a powder layer in each case. The material 28 is provided in the processing plane 32, for example by applying a powder layer with a coating tool in the processing plane 32, or after partially melting the layer and lowering the component 30 by one layer thickness, a new powder layer is applied, for example with a coating device.A processing beam generation device 20 emits a processing beam 24. The processing beam 24 is guided to a beam shaping device 22, which performs an intended beam shaping on the processing beam 24. The shaped processing beam 24 is subsequently guided to a positioning device 26, which is configured to direct the shaped processing beam 24 onto the processing plane 32 and to position it there along a path of exposure positions, i.e., the processing beam 24 is emitted from the processing beam generation device 20 onto the processing plane 32 in the build space. The processing beam 24 forms a freely selectable irradiance profile 10 in the processing plane 32 such that the irradiance profile 10 has at least one functional region 12 and / or at least one melting region 14.Here, an irradiance value of the irradiance profile 10 in the melting region 14 is greater than an irradiance limit value corresponding to a melting temperature of the material 28. Furthermore, the irradiance value in the functional region 12 is smaller than the irradiance limit value and is sufficient to change a material property of the component 30.

[0060] By irradiating the material with the processing beam 24, the material 28 can be locally melted and solidified layer by layer in the melting region 14 to form a layer of the component 30. Metallic components 30, in particular, can be easily manufactured using laser beam melting or laser beam sintering processes. Instead of a laser beam, an electron beam can also be used. Laser beams and electron beams are collectively referred to herein as processing beams. Furthermore, the material can be a multi-material, a mixture of several materials, or can be modified within the processing plane 32.

[0061] The embodiments and their further developments thus demonstrate how an additive layer-based manufacturing device can be implemented that can integrate processes, for example, for eliminating residual stresses, into a single processing beam. Reference symbols:

[0062] 10 Irradiance profile

[0063] 12 Functional area

[0064] 12.1 Functional area 1

[0065] 12.2 Functional area 2

[0066] 14 Melting range

[0067] 16 direction

[0068] 20 processing beam generation device

[0069] 22 Beam shaping device

[0070] 24 processing beam

[0071] 26 Positioning device

[0072] 28 Material

[0073] 30 components

[0074] 32 processing level

[0075] 34 Platform

[0076] 36 tub

[0077] 41 Area

[0078] 42 Area

[0079] 43 Area

[0080] 44 Area

[0081] 45 area

[0082] 51 Area

[0083] 52 Area

[0084] 53 Area

[0085] 54 Area

[0086] 57 Area

[0087] 58 Scan direction

[0088] 59 Powder

[0089] 60 freshly created tracks

[0090] 61 frozen neighbor's lane

Claims

Patent claims 1. A method for the additive production of a three-dimensional component (30) in a layered construction device comprising a construction space and a processing beam generation device (20), comprising the steps: Providing at least one material (28) in a processing plane (32) in the construction space for layer-by-layer production of the component (30) from the at least one material (28); Emitting a processing beam (24) from the processing beam generating device (20) onto the processing plane (32) in the construction space and Forming a freely selectable irradiance profile (10) in the processing plane (32) by the processing beam (24) such that the irradiance profile (10) has at least one functional region (12) and / or at least one melting region (14), wherein a value of an irradiance of the irradiance profile (10) in the melting region (14) is greater than an irradiance limit value corresponding to a melting temperature of the at least one material (28), and the value of an irradiance in the functional region (12) is less than the irradiance limit value and is sufficient to change a material property of the component (30) during the generation of the melting track (SdT) at least in some regions - next to the track just created, the already solidified neighboring track and / or the neighboring tracks already created or the melting track yet to be created and / or next to a melting track not just created in the direct powder environment 2. The method according to claim 1, wherein the layer building device comprises a beam shaping device (22), only a single processing beam (24) is generated in the processing beam generating device (20), and its irradiance profile (10) is shaped in the beam shaping device (22).

3. Method according to one of the preceding claims, wherein the irradiance profile (10) is positioned by means of a positioning device (26) along a path of exposure positions in order to form a component layer.

4. Method according to one of the preceding claims, wherein the functional region (12) has a predetermined pose to the melting region (14), and the processing beam generating device (20), the beam shaping device (22) and the positioning device (26) cooperate to adapt the predetermined pose depending on a path of exposure positions.

5. Method according to one of the preceding claims, wherein the beam shaping device (20) statically or dynamically adapts the irradiance profile (10) as a function of component geometry, heating rate, cooling rate, light absorption capacity, layer thickness, processing beam power, scanning speed, track spacing, volume energy density, scanning direction and / or pulse rate of the processing beam (24).

6. Method according to one of the preceding claims, wherein the beam shaping device (22) forms the irradiance profile of the processing beam (24) by means of a diaphragm, by means of a field mapper, by means of beam integrators, by means of an acousto-optical deflection element, in particular with a switching rate in the range from 1 kHz to 1 MHz, preferably up to 200 kHz, and more preferably up to 100 kHz and / or by means of a liquid crystal element.

7. Method according to one of the preceding claims, wherein the value of the irradiance in the functional area (12) is set such that a homogenized or specifically controlled thermal gradient, predetermined phase precipitations and / or phase resolutions, a heat treatment, a texture change and / or a lattice equalization or lattice distortion, in particular for the targeted control of material properties, reduction of residual stresses, microstructure adaptation, defect minimization and / or defect healing is / are generated in the irradiated component (30).

8. Method according to one of the preceding claims, wherein the construction space is heated by means of a heating element.

9. Method according to one of the preceding claims, wherein the processing beam (24) is a laser beam.

10. Layer building device with a construction space and a processing beam generating device (20), wherein the layer building device is designed to carry out the method according to one of the preceding claims.

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