Method and device for additively manufacturing workpieces with reduced hot cracking

Abstract

The invention relates to a method for setting the radiation intensity of a beam in a manufacturing process for additively manufacturing a component. During the manufacturing process, components are produced in that a construction material is deposited layer by layer, and the construction material is solidified in each deposited layer by supplying radiation energy, by means of a beam, to the points of the layer which are associated with the cross-section of the component in said layer in that the beam is moved along a plurality of trajectories in the cross-section of the component by means of a beam moving device, preferably a controllable beam moving device, in order to melt the construction material at the points which are associated with the cross-section of the component, wherein the radiation intensity of the beam is set within a region of incidence of the beam on the construction material using a beam profile setting device. The method is characterized in that the radiation intensity of the beam is set in such a way that the distribution of the radiation intensity in the region of incidence of the beam on the construction material changes by at least 1% per µm at at least one point.

Description

[0001] Method and device for additive manufacturing of workpieces with reduced hot cracking

[0002] The present invention relates to a method for adjusting a radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component, an additive manufacturing method in which this method is carried out, a computer-aided method for generating control command data for adjusting a radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component and a beam profile adjusting device for generating a beam in a manufacturing process for the additive manufacturing of a component.

[0003] The present invention relates in particular to additive manufacturing methods and devices in which a component is melted by irradiating layers of a starting material, which is in powder or paste form, with electromagnetic or particle radiation, in order to form a solid after cooling. Examples of such processes are selective laser sintering (SLS) or selective laser melting (SLM). Selective laser melting, in particular, processes metallic starting materials, and in recent years, the processes have evolved to the point where even components that must meet high requirements regarding mechanical and thermal properties can be manufactured using additive manufacturing.

[0004] For example, turbine guide vanes and rotor shells are exposed to high thermal, corrosive, and oxidative stresses. Due to typically high operating temperatures, creep damage, for example, due to grain boundary sliding, can occur. This damage mechanism can generally be counteracted by a coarser grain structure. Therefore, the aim is to manufacture the components with a single-crystal microstructure or at least with a directional solidified grain structure with the crystallites oriented at least approximately in the future main loading direction.

[0005] Nickel-based alloys (e.g., Hastelloy, Inconel), tungsten-molybdenum alloys, or titanium alloys are preferred materials for the production of highly stressed components. Nickel-, cobalt-, and / or iron-based superalloys are particularly preferred. However, difficulties in using nickel-based alloys as build-up materials arise from the tendency for hot cracks to form during welding (melting and solidification) of these materials. In particular, a high proportion of alloying elements leads to difficulties in the processability, e.g., with regard to weldability, of the materials. This is also due to the formation of hot cracks during solidification.

[0006] It is therefore an object of the present invention to provide a method and a device by means of which hot cracking can be reduced during the production of components by means of an additive manufacturing process.

[0007] The object is achieved by a method for adjusting a radiation intensity according to claim 1, an additive manufacturing method according to claim 8, a method for generating control command data according to claim 14, a beam profile adjustment device according to claim 15, and an additive manufacturing device according to claim 16. Further developments of the invention are specified in the dependent claims. The methods can also be further developed by the features of the devices set out below or in the dependent claims, or vice versa. The features of the devices and methods can also be used for further development among each other.

[0008] A method according to the invention for adjusting the radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy by a beam to those locations of the layer that are associated with the cross-section of the component in this layer, by moving the beam along a plurality of trajectories in the cross-section of the component by means of a preferably controllable beam movement device in order to melt the build-up material at the locations that are associated with the cross-section of the component, and wherein the radiation intensity of the beam is adjusted using a beam profile adjustment device within an impact area of ​​the beam on the build-up material, is characterized in thatthat the radiation intensity of the beam is adjusted so that its distribution in the area of ​​impact of the beam on the building material changes by at least 1% per pm at at least one point.

[0009] Additive manufacturing devices and methods to which the present invention relates are, in particular, those in which energy is selectively supplied to a layer of a formless building material as electromagnetic radiation or particle radiation. The working plane (also referred to as the building plane) is a plane in which the upper side of the layer to which the energy is supplied lies and is also referred to here as the layer plane. The radiation energy can be generated, for example, by a laser or an electron beam source, although a plurality of radiation sources and / or beams can also be used. The radiation supplied to the building material heats it and thereby causes a sintering or melting process. In particular, the present invention relates to laser melting devices and the associated methods.An application of the invention in connection with additive manufacturing methods and devices in which a metallic or at least metallic-containing build-up material is used, for example a metal powder or metal alloy powder, is particularly advantageous. The invention is preferably applied in a manufacturing process in which the build-up material (usually in powder form) consists of a material that contains a nickel-based alloy (e.g. Hastelloy, Inconel, MAR M 247), tungsten-molybdenum alloys or titanium alloys, in particular nickel-, cobalt-, and / or iron-based superalloys, or at least contains such a material. It should be noted at this point that by means of an additive manufacturing device according to the invention, not only one object, but also several objects can be produced simultaneously.When the present application refers to the production of an object, it is understood that the respective description is equally applicable to additive manufacturing methods and devices in which several objects are produced simultaneously.

[0010] The term "beam" here does not imply that the beam diameter must be very small. Rather, the beam impact area on the build material (in the build plane or layer plane) can certainly have a larger diameter (e.g., approximately 250 pm). The beam is preferably a laser-generated beam, generated, for example, using one or more single-mode lasers, e.g., a fiber laser with a power of 3 kW and a wavelength of 1070 nm. The beam movement device is, for example, an XY galvanometer scanner. The beam profile adjustment device is designed to adjust the distribution of the radiation intensity in a plane perpendicular to the beam direction, particularly in the area where the radiation impacts the build material.A change in radiation intensity of 1% per pm expresses that the difference between the values ​​of radiation intensity at two points in the impact area that are 1 pm apart is 1% of the maximum intensity of the beam in the impact area.

[0011] In order to provide a laser beam whose intensity distribution in the impact area on the building material changes by at least 1% per pm at least at one point, a beam combination device disclosed in WO 2020 / 099172 A1, for example, can be used for the beam profile adjustment device. The beam combination device couples a first laser beam and a different second laser beam in a beam path such that both beams can be moved jointly over the building material by means of the beam movement device. The superposition of the two laser beams then provides an intensity distribution with the desired properties in the impact area. In particular, it is also conceivable to guide the laser radiation, at least partially, via a multi-fiber optical fiber, with different radiation intensities then being supplied to the different fibers.The latter can be generated by a plurality of laser sources and / or by splitting laser beams into several sub-beams. In particular, the ratio of the radiation intensities transmitted by the individual fibers can also be influenced or determined by the design of the fibers.

[0012] Furthermore, the beam profile adjustment device can comprise at least one micro-optical element, which can be controlled by a control device or can be controlled by a control device. This can be a so-called diffractive optical element (DOE). DOEs can, for example, operate reflectively or transmissively and modify the wavefront of an incident beam by locally modulating the phase and / or amplitude of the reflected or transmitted partial beams.

[0013] Furthermore, the beam profile adjustment device can also be implemented using a controllable array of liquid crystals.

[0014] A beam trajectory is the path a beam follows in the build plane when the beam is directed at the build material to generate the build material at the locations corresponding to the component's cross-section by melting the build material. It is a sequence of locations in the build plane specified in the control data of the beam movement device. The sequence in the control data specifies the chronological order in which the beam is to be directed at these locations by the beam movement device, i.e., these locations are to be scanned with the beam.

[0015] For the purposes of the method according to the invention, the impact area is a surface on the build material in the build plane onto which the beam impacts. The impact area therefore corresponds to a two-dimensional extension on the build material on the build plane. When scanning the areas of a component cross-section to be hardened, a distinction is sometimes made between an inner region and an edge region (often an edge line whose width roughly corresponds to the diameter of the beam impact area on the build material in the build plane perpendicular to the direction of movement of the beam) of a component cross-section. The inner region and / or the edge region are hardened by moving the beam along trajectories that are usually essentially parallel to one another, which can be straight and parallel to one another or non-straight and parallel to one another.The surfaces are hatched, so to speak, which is why the individual trajectories are also referred to as "hatch lines." In particular, in this application, the term "trajectory" is often used synonymously with "hatch line" or scan line, even though, strictly speaking, a trajectory refers to a line specified in the control data (of zero width), and a "hatch line" or scan line refers to a track in the build plane with a width other than zero, which roughly corresponds to the diameter of the beam impact area on the build material in the build plane perpendicular to the beam's direction of travel. According to the above definition, the width of the scan line therefore corresponds to the width of the impact area.To account for the non-zero widths of the melt traces in the build-up material, the trajectories are spaced apart from each other, allowing for a uniform, seamless energy input into the build-up material during a scan. Within the scope of the invention, it is preferred that the trajectories be specified as straight lines.

[0016] In particular, the radiation intensity in the impact area can be distributed radially symmetrically, for example a donut profile, Gaussian profile or a so-called tophat profile, i.e. a profile in which the radiation intensity is more or less constant but drops off towards the edge of the impact area. However, other non-rotationally symmetric profiles are also conceivable, such as a sickle beam profile (also called a "C-shape") and a ramp profile (profile in the shape of an inclined plane, whereby in practice there can be secondary maxima in addition to a main maximum in the intensity or the intensity can also drop in steps). According to the invention, a thermal conduction welding process is preferably carried out during the melting of the build-up material.

[0017] According to one aspect of the invention, the radiation intensity is adjusted such that its distribution in the area of ​​impact of the beam on the building material decreases at at least one point towards the edge of the impact area by at least 1% per pm, preferably at least 2% per pm, more preferably at least 3% per pm, most preferably at least 4% per pm, and / or in which the radiation intensity is adjusted such that its distribution at the at least one point towards the edge of the impact area decreases by at most 5% per pm, more preferably at most 7% per pm, more preferably at most 9% per pm.

[0018] The inventors were able to determine that the hot cracking behavior is more favorable the steeper the radiation intensity drops toward the edge of the impact zone. This can be explained by the fact that a steep drop in radiation intensity can prevent the formation of agglomerates of powder particles at the edge of the radiation impact zone, which would otherwise lead to instabilities and hot cracking in the subsequent process.

[0019] Preferably, the radiation intensity is adjusted such that its distribution in the impact area on the build-up material varies such that, in the event of rotation of the beam, the decrease in radiation intensity towards the edge of the impact area changes at at least one point on the layer and / or the position of the impact area changes with respect to the point on the layer.

[0020] The rotation can take place at any angle, whereby the axis of rotation is assumed to be the beam axis, i.e. the direction of the beam.

[0021] With this approach, there is no radially symmetric distribution of the radiation intensity in the impact area. Rather, the radiation intensity in the direction of the trajectory can exhibit a different distribution than in a direction perpendicular to it, for example, it can be distributed axially symmetrically (with the trajectory as the axis of symmetry). This means that in the event of rotation, different radiation intensity is delivered to certain areas of the build-up material.

[0022] According to a further aspect, the radiation intensity is adjusted such that at least 90%, preferably at least 95%, particularly preferably at least 99%, of the total radiation power is distributed within an impact region of the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm, and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

[0023] Since in practice the radiation intensity at the edge does not abruptly return to a value of zero, the area of ​​the impact region must be defined in some way. In the present application, the area of ​​the impact region is defined as the area in the build plane onto which at least 90%, preferably at least 95%, particularly preferably at least 99%, of the total radiant power is incident. In cases where the radiation intensity is not distributed radially symmetrically, the maximum extent of the impact region in the build plane can be used as the diameter of the impact region. According to the above definition, a simple increase in radiant power also causes the impact region to become correspondingly larger. This is disadvantageous because it does not change the ratio between the radiation intensity in the impact region and the radiation intensity outside the impact region.The method according to the invention advantageously achieves an increase in the radiation intensity in the impact area without increasing the diameter of the impact area. In contrast to a simple increase in the radiation power, this changes the ratio between the radiation intensity in the impact area and outside the impact area, or rather, it is achieved by distributing a predominant portion of the radiation intensity (as explained above, at least 90%, preferably at least 95%, particularly preferably at least 99%) in the impact area.

[0024] The specified procedure, i.e., the combination of a minimum steepness of the intensity profile decline with the relatively large extent of the radiation impact area compared to the prior art, makes it possible to achieve a wide, flat melt pool, allowing the preferred thermal conduction welding process to occur during melting. In particular, the inventors were able to determine that hot cracking behavior can be advantageously influenced by combining an enlarged impact area with a high slope of the radiation intensity distribution in the impact area. A low slope otherwise causes powder particles to agglomerate with an increased laser beam diameter, which leads to instabilities and renewed hot cracking in the further process.

[0025] According to a further aspect, the radiation intensity is adjusted such that, starting from a point on the trajectory lying within the impact area, the distribution of the radiation intensity in the impact area of ​​the beam on the building material has a different extent in a direction perpendicular to the trajectory than in the direction opposite to this perpendicular direction.

[0026] Such a distribution of radiation intensity is particularly advantageous during hatching, i.e., the sequential scanning of the build-up material along trajectories that are, at least in sections, essentially parallel to one another. Preferably, it is ensured that in a direction in which the trajectories are scanned successively (trajectory sequence direction, i.e., the direction perpendicular to the course of the trajectories), the impact area has a wider extension in the direction of the subsequent and / or previous trajectory, thus promoting or enabling a thermal conduction welding process. In particular, a wide impact area or a wide melt pool in combination with an overlap of adjacent trajectories promotes crystal growth in the vertical direction.

[0027] According to a further aspect, the beam movement device is controllable and is controlled such that the distance between two adjacent trajectories which run substantially parallel to each other is less than or equal to 50% of the beam width of the beam, preferably less than or equal to 35% of the beam width and greater than or equal to 15% of the beam width.

[0028] Here, the extent of the impact area perpendicular to the trajectory is defined as the beam width. The specified overlap of the impact areas of the beams used when scanning successive trajectories makes it possible to achieve a wide, flat melt pool, allowing the preferred thermal conduction welding process to occur during melting. Furthermore, the specified overlap and the radiation intensity distribution described above make it possible to achieve a wide, flat melt pool, particularly with a wider extent in the direction of the subsequent and / or previous trajectory.

[0029] This approach can also be used when the parallel trajectories are not straight, e.g. in the case of so-called "onion hatching", in which the build-up material is scanned in a spiral or concentric circles.

[0030] According to a further aspect, the beam movement device is controllable and is controlled such that the beam is moved along a trajectory at a speed that is greater than or equal to 1 m / s.

[0031] By specifying the minimum scanning speed, it is ensured that not too much power is introduced into the build material, so that a thermal conduction welding process can be ensured when melting the build material.

[0032] Preferably, the speed at which the beam is moved along a trajectory is a value greater than or equal to 1 m / s and less than or equal to 2 m / s.

[0033] In an additive manufacturing method according to the invention for the additive production of a three-dimensional component using an additive manufacturing device, a method according to the invention for adjusting the radiation intensity of a beam is carried out. In particular, the additive manufacturing method according to the invention can be a selective laser melting (SLM) process.

[0034] If a beam generated by a laser operated in continuous wave mode is used in the additive manufacturing process for melting the build-up material along at least one of the trajectories, this beam can be moved along the trajectories at a speed greater than or equal to 1 m / s.

[0035] According to one aspect of the invention, in the additive manufacturing process, the variation of the radiation intensity in the impact area on the build-up material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that after cooling of the previously melted build-up material, the proportion of large-angle grain boundaries is less than 75%, preferably less than 66%, more preferably less than 50%, most preferably less than 33%.

[0036] A high-angle grain boundary is defined here as a grain boundary where the orientation of adjacent crystal regions or crystallites differs by at least 15°. In the specified procedure, in which the radiation intensity is adjusted according to the invention in an additive manufacturing process, the degree of polycrystallinity in the manufactured component is limited, since the degree of polycrystallinity increases with the proportion of high-angle grain boundaries. As the degree of polycrystallinity increases, the tendency for hot cracking also generally increases.

[0037] It should be noted that, with the desired limitation of polycrystallinity according to the invention, the degree of polycrystallinity can also be defined via the aspect ratio of the grains or via the extent to which the crystal regions are generated by epitaxial growth. According to a further aspect, in the additive manufacturing method according to the invention, the variation of the radiation intensity in the area of ​​impact on the build-up material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that, after cooling of the previously melted build-up material, the orientation of the grains relative to a perpendicular to the plane of the layer is a maximum of 15°.

[0038] Here, the orientation of the grains is defined as the angle between the direction of maximum extension of a grain and the normal. The normal to a layer plane usually corresponds to the direction in which the layers are stacked.

[0039] By means of the specified procedure, the crystallites (grains) in the component (preferably the single crystal of the single-crystalline component) can be aligned in a preferred direction, which is preferably selected so that it essentially or exactly coincides with the direction in which the greatest mechanical stress occurs during later use of the component.

[0040] According to a further aspect, the variation of the radiation intensity in the impact area on the building material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that after cooling of the previously melted building material, the maximum dimension of the grains is greater than or equal to 20 times, preferably greater than or equal to 50 times, more preferably greater than or equal to 100 times, the distance between two adjacent trajectories.

[0041] The grain size is defined here as the average diameter of the grains (crystallites). The specified coordination between grain size and trajectory spacing reflects the fact that a conduction welding process with a flat, extended molten pool is desired. According to a further aspect, the variation of the radiation intensity in the impact area on the build-up material, the speed at which the beam is moved along the plurality of trajectories, and the spacing between adjacent trajectories are selected such that, after cooling of the previously molten build-up material, the extent of the grains perpendicular to the planes of the layers is greater than or equal to 20 times, preferably greater than or equal to 50 times, and even more preferably greater than or equal to 100 times, the spacing between two adjacent trajectories.

[0042] According to a further aspect of the invention, the directions of superimposed trajectories in successive layers are rotated relative to each other by an angle which is substantially 90°, preferably exactly 90°.

[0043] The angle between two superimposed trajectories (trajectories spaced apart in the build direction or z-direction) can be determined by projecting the trajectories onto a plane parallel to both (which is parallel to the build plane or coincides with the build plane). Rotating the trajectories by 90° ensures that the crystal structure is maintained in the z-direction.

[0044] A computer-aided method according to the invention for generating control command data for adjusting a radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component, wherein in the manufacturing process components are produced by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy by a beam to those locations of the layer that are assigned to the cross-section of the component in this layer, by moving the beam by means of a preferably controllable beam movement device along a plurality of trajectories in the cross-section of the component in order to melt the build-up material at the locations that are assigned to the cross-section of the component, wherein the radiation intensity of the beam is adjusted using a

[0045] Beam profile adjustment device is adjusted within an impact area of ​​the beam on the build field, and wherein the control command data are used to control the beam profile adjustment device, characterized in that the control command data are generated such that a distribution of the radiation intensity in the impact area of ​​the beam on the build material changes at least at one point by at least 1% per pm and / or that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation power is distributed within an impact area of ​​the beam on the build material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

[0046] In an additive manufacturing process, production is typically controlled based on computer-based model data of the component to be manufactured. The model data contains a geometric description of the cross-sections of the component to be manufactured, which are assigned to the layers during layer-by-layer production, in particular a three-dimensional CAD model. However, other geometric description options are also available, such as a description using a set of parameters and a design specification.

[0047] The control command data for setting a radiation intensity are generally part of a control data set, which is considered to be the entirety of all control data specified for controlling the manufacturing process in an additive manufacturing device. The control data relating to an individual layer is usually referred to as a layer data set. In the present application, it is particularly assumed that a layer data set contains a data model of locations of an object cross-section or partial object cross-section that are to be solidified in a layer by means of one or more beams during the manufacturing process. In addition, further information relating to the production of the object cross-section can be included, in particular the chronological sequence in which locations corresponding to an object cross-section or partial object cross-section are to be solidified by specifying scan lines orTrajectories along which the beam is to be moved, a temporal sequence of scanning a plurality of scan lines or trajectories, or, for example, the layer thickness or irradiation parameter values, such as the diameter or travel speed of a beam impinging on the build material, etc.

[0048] In a preferred embodiment, the control command data for adjusting a radiation intensity comprises data for controlling an array of liquid crystals. Arrays of liquid crystals are divided into regions, usually into square columns or square regions (“pixels”). In each region (column or pixel), the refractive index can be modulated by an electrical signal. Before it hits the array, the beam is expanded and collimated. As a result, the beam hits several, for example all, regions of the array, and different beam components pass through different regions (columns or pixels) of the array. The beam is then refocused and directed, as described above, onto the build area to solidify the build material. By electrically modulating the refractive index of the regions of the array, different beam components of the beam experience different refractive indices.In this way, depending on the control of the electrical signal or the modulation of the refractive index across the regions of the array, beam diffraction or beam interference effects can be realized. The adjustment of the radiation intensity is then based on or depends on the aforementioned beam diffraction or beam interference effects. In other words, this means that the control command data for adjusting a radiation intensity comprises data for controlling an array of liquid crystals, and that the adjustment of the radiation intensity depends on the data for controlling the array of liquid crystals. The data for controlling the array of liquid crystals is then a special case of control command data for adjusting the radiation intensity and is therefore part of a control data set that comprises the entirety of all control data specified for controlling the manufacturing process in an additive manufacturing device.The data for controlling the liquid crystal array can be generated together with the remaining control command data, or part of the control command data can be generated as data for controlling the liquid crystal array. Alternatively, the data for controlling the liquid crystal array can be generated in a separate step, and the control command data can be subsequently supplemented with the data for controlling the liquid crystal array.

[0049] A preferred variant of the computer-aided method according to the invention for generating control command data for adjusting a radiation intensity of a beam in the manufacturing process for the additive manufacturing of a component, wherein the radiation intensity of the beam is adjusted using a beam profile adjustment device within an impact area of ​​the beam on the construction field and the control command data serve to control the beam profile adjustment device, is characterized in that the control command data comprise data for controlling an array of liquid crystals, wherein the adjustment of the radiation intensity depends on the data for controlling the array of liquid crystals.

[0050] A further preferred variant of the computer-aided method according to the invention for generating control command data for adjusting a radiation intensity of a beam in the manufacturing process for the additive manufacturing of a component is characterized in that the control command data and / or the data for controlling the array of liquid crystals are generated in such a way that a distribution of the radiation intensity in the area of ​​impact of the beam on the building material changes at least at one point by at least 1% per pm and / or that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation intensity is distributed within an area of ​​impact of the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

[0051] A beam profile adjustment device according to the invention for generating a beam in a manufacturing process for the additive manufacturing of a component, wherein in the manufacturing process components are produced by applying a building material layer upon layer and solidifying it in each applied layer by supplying radiation energy to those points of the layer that are assigned to the cross-section of the component in this layer, wherein the beam profile adjustment device is designed to adjust the distribution of a radiation intensity within an impact area of ​​the beam, is characterized in that the beam profile adjustment device generates the beam such that the radiation intensity in the impact area of ​​the beam on the building material changes at least at one point by at least 1% per pm and / or that at least 90%, preferably 95%, particularly preferably 99%,the total radiation power is distributed within an impact area of ​​the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.,

[0052] In a preferred embodiment, the beam profiling device comprises a multiple light splitter (e.g., a beam splitter or a diffractive element) by which the radiant power can be distributed among optical fibers, e.g., optical fibers. These optical fibers can also be part of the beam profiling device. Alternatively, the optical fibers can be attached to the beam profiling device. The fact that the optical fibers are attached to the beam profiling device does not mean that they necessarily have to be in the immediate vicinity of the beam profiling device or that they necessarily have to be mechanically connected to the beam profiling device. It is sufficient that the beam emanating from the beam profiling device can be coupled into the additional optical fibers. In an alternative embodiment, several beams are coupled into a plurality of optical fibers, i.e.,without the use of a multiple light splitter. In this case, the optical fibers are considered part of the beam profile adjustment device. The beam profile can be adjusted by superimposing several beams, which originate either from several independent laser sources or from a single laser source. Even before coupling into a light guide, a beam has a specific beam profile. However, propagation in the light guides inevitably changes the beam profile. The change in the beam profile during propagation in a light guide can be predicted, for example, through simulation. The properties of a light guide can then be selected such that the change in the beam profile due to propagation in the light guide contributes to the generation of a desired beam profile.In other words, a beam profile is adjusted before coupling into a light guide and the properties of a light guide are selected in such a way that the combination of the adjustment of the beam profile and the change of this by propagation in the light guide creates a desired beam profile.

[0053] An additive manufacturing device according to the invention for producing a three-dimensional object with an application device for applying a building material layer upon layer and an energy input device for supplying radiation energy by means of a beam to those locations of a layer which are assigned to the cross-section of the object in this layer, which has: a beam profile device for adjusting a radiation intensity of the beam and a beam movement device for moving the beam along a plurality of trajectories, wherein the building material is melted at the locations which are assigned to the cross-section of the component in the layer along the trajectories, is characterized in that the beam profile device adjusts the radiation intensity of the beam such that the radiation intensity in the area of ​​impact of the beam on the building material changes at least at one location by at least 1% per pm.

[0054] A further variant of a method for adjusting the radiation intensity of a beam and for moving the beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy through the beam to those locations of the layer that are associated with the cross-section of the object in this layer, by moving the beam by means of a preferably controllable beam movement device along a plurality of trajectories in the cross-section of the object in order to melt the build-up material at the locations that are associated with the cross-section of the component, wherein the radiation intensity of the beam is adjusted using a beam profile adjustment device, is characterized in thatthat the radiation intensity of the beam is adjusted such that its distribution in the area of ​​impact of the beam on the building material changes at least at one point by at least 1% per pm and that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation intensity is distributed within an area of ​​impact of the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm, and further characterized in that the beam movement device is controlled such that the distance between adjacent trajectories, which run essentially parallel to one another, is less than 50% of the beam width of the beam, preferably less than or equal to 35% of the beam width, particularly preferably greater than or equal to 15% of the beam width, and the energy input device is controlled such thatthat the beam is moved along a trajectory at a speed greater than or equal to 1 m / s.,

[0055] A method according to the invention for introducing radiation energy by means of a beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a building material layer upon layer and solidifying it in each applied layer by supplying radiation energy to those locations of the layer that are associated with the cross-section of the component in this layer, comprises: adjusting a radiation intensity of the beam using a beam profile adjusting device within an impact region of the beam on the building material and moving the beam by means of a, preferably controllable, beam moving device along a plurality of trajectories in the cross-section of the component, wherein the building material is melted at locations that are associated with the cross-section of the component.The method is characterized in that the radiation intensity is adjusted such that its distribution in the area of ​​impact of the beam on the building material changes at least at one point by at least 1% per pm and that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation intensity is distributed within an area of ​​impact of the beam on the building material whose diameter is at most 470 pm, more preferably 420 pm, even more preferably 300 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.Furthermore, the method is characterized in that the beam is moved such that the distance between adjacent trajectories which run substantially parallel to one another is less than 50% of the beam width of the beam, preferably less than or equal to 35% of the beam width, particularly preferably greater than or equal to 15% of the beam width, and the energy input device is controlled such that the beam is moved along a trajectory at a speed which is greater than or equal to 1 m / s.

[0056] An energy input device according to the invention for inputting radiation energy by means of a beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy to those locations of the layer that are associated with the cross-section of the component in this layer, comprises: a beam profile adjustment device that is designed to adjust a radiation intensity of the beam and a, preferably controllable, beam movement device for moving the beam along a plurality of trajectories in the cross-section of the component, wherein the build-up material is melted at the locations that are associated with the cross-section of the component.

[0057] The energy input device is characterized in that the beam profile adjustment device adjusts the radiation intensity of the beam such that its distribution in the area of ​​impact of the beam on the building material changes at least at one point by at least 1% per pm and that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation intensity is distributed within an area of ​​impact of the beam on the building material whose diameter is at most 470 pm, more preferably 420 pm, even more preferably 300 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

[0058] It is further characterized in that the beam movement device is controlled such that the distance between adjacent trajectories which run substantially parallel to one another is less than 50% of the beam width of the beam, preferably less than or equal to 50% of the beam width, particularly preferably greater than or equal to 15% of the beam width, and the energy input device is controlled such that the beam is moved along a trajectory at a speed which is greater than or equal to 1 m / s.

[0059] Fig. 1 shows a schematic, partially sectioned view of an exemplary device for additively manufacturing a three-dimensional object according to the invention.

[0060] Fig. 2 shows schematically the course of the radiation intensity along a section through the center of the incident surface of a beam with radially symmetric radiation intensity and donut shape of the intensity profile.

[0061] Fig. 3 shows schematically the course of the radiation intensity along a section through the center of the incident surface of a beam with radially symmetric radiation intensity and Gaussian shape of the intensity profile.

[0062] Fig. 4 shows schematically the course of the radiation intensity along a section through the center of the incident surface of a beam with radially symmetric radiation intensity and tophat shape of the intensity profile.

[0063] Fig. 5 schematically shows two trajectories along which the beam is moved when scanning the build material.

[0064] Fig. 6 shows a three-dimensional representation of a donut-shaped intensity distribution. Fig. 7 shows a three-dimensional representation of a "tophat" intensity distribution.

[0065] Fig. 8 shows a common procedure for scanning ("hatching") the build-up material with electromagnetic radiation

[0066] Fig. 9 shows a three-dimensional representation of a ramp-shaped intensity distribution (ramp distribution).

[0067] For a description of the invention, an additive manufacturing device according to the invention will first be described below using the example of a laser melting device with reference to Fig. 1.

[0068] For constructing an object 2, the laser sintering or laser melting device 1 contains a process chamber or build chamber 3 with a chamber wall 4. Arranged within the process chamber 3 is a build container 5 open at the top and with a container wall 6. A work plane 7 is defined by the upper opening of the build container 5, with the area of ​​the work plane 7 located within the opening, which can be used to construct the object 2, being referred to as the build field 8.

[0069] Arranged within the build container 5 is a support 10 movable in a vertical direction V, to which a base plate 11 is attached, which closes off the container 5 at the bottom and thus forms its base. The base plate 11 can be a plate formed separately from the support 10 and fastened to the support 10, or it can be formed integrally with the support 10. Depending on the powder used and the process, a build platform 12 can be attached to the base plate 11 as a build base, on which the object 2 is built. However, the object 2 can also be built on the base plate 11 itself, which then serves as the build base. In Fig. 1, the object 2 to be formed in the container 5 on the build platform 12 is shown below the work plane 7 in an intermediate state with several solidified layers, surrounded by unsolidified build material 13.The laser melting device 1 further includes a reservoir 14 for a build material 15, in this example a powder that can be solidified by electromagnetic radiation, and a coater 16 movable in a horizontal direction H for applying the build material 15 within the build field 8. Optionally, a heating device, e.g., a radiant heater 17, can be arranged in the process chamber 3. An infrared radiator, for example, can be provided as the radiant heater 17.

[0070] The exemplary additive manufacturing device 1 further includes an energy input device 20 with a laser 21 that generates a laser beam 22, which is focused onto the working plane 7 via a beam profile adjustment device 26 and an XY galvanometer scanner 23 as a beam movement device and optionally a focusing device 24 via a coupling window 25 that is attached to the top of the process chamber 3 in the chamber wall 4.

[0071] In laser melting, an energy input device can comprise, for example, one or more gas or solid-state lasers or any other type of laser, such as laser diodes, in particular VCSELs (Vertical Cavity Surface Emitting Lasers) or VECSELs (Vertical External Cavity Surface Emitting Lasers), or a row of these lasers. The specific structure of a laser sintering or melting device shown in Fig. 1 is therefore only exemplary for the present invention and can, of course, also be modified, particularly when using an energy input device other than the one shown.

[0072] The laser melting device 1 further includes a control device 29, via which the individual components of the device 1 are controlled in a coordinated manner to carry out the construction process. Alternatively, the control device can also be mounted partially or completely outside the additive manufacturing device. The control device can include a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separately from the additive manufacturing device in a storage device, from where it can be transferred (e.g., via a network) into the additive

[0073] manufacturing device, in particular into the control device.

[0074] During operation, the control device 29 lowers the carrier 10 layer by layer, controls the coater 16 to apply a new powder layer, and controls the energy input device 20 to solidify the respective layer at the locations corresponding to the respective object by means of the laser by scanning these locations with the laser beam.

[0075] All statements made below apply not only to laser melting devices, but also to other types of additive manufacturing devices in which heat energy is introduced into the build material by means of radiation.

[0076] In the additive manufacturing device just described as an example, a manufacturing process takes place in such a way that the control device 29 processes a control data set.

[0077] The control data set tells the energy input device at which point on the working plane 7 the radiation is to be directed at each point in time during the scanning process of the build-up material with the laser beam.

[0078] In a procedure according to the invention for producing objects in which strongly anisotropic mechanical properties are desired, e.g. turbine blades, metallic construction material is preferably used, in particular one which consists mainly, preferably more than 90%, of a nickel-based alloy, e.g. Inconel or MAR M 247 or CM 247 LC, and which is melted by introducing the radiation energy.

[0079] Fig. 8 shows a typical procedure for scanning the build material with electromagnetic radiation. In Fig. 8, an object cross-section 50 is divided into an inner region or core region 52 and a contour region 51. Different parameters for energy input into the build material are generally assigned to the contour region 51 than to the inner region 52. The inner region 52 is typically solidified by dividing the inner region 52 into subregions 53, which usually have an approximately rectangular or square shape and are therefore also referred to as "strips" or "squares." The inner region 52 is then scanned subregion by subregion with the laser beam.

[0080] As shown in Fig. 8, in each partial area 53, the laser beam is moved along parallel paths (hatch lines) 54 across the build material, resulting in a hatch-like movement pattern when scanning each partial area 53 with the laser beam. This process is also referred to as "hatching" in technical jargon. In Fig. 8, the direction of movement of the laser beam is illustrated by arrows. It can be seen that the directions of movement for adjacent hatch lines 54 are opposite to each other.

[0081] Fig. 5 illustrates in detail the situation for two adjacent hatch lines 54 (also referred to as trajectories). The trajectories illustrate the sequence of points on the build material layer that are scanned one after the other, in other words, the positions that are specified to the energy input device in the control data set for an energy input in chronological succession. In practice, the impact area of ​​the laser beam on the surface of the build material has an extent other than zero, which is illustrated in Fig. 5 by a circular area 100. The edge of the impact area is defined such that 99% of the radiation power of the laser beam impinges on the area lying within the edge.

[0082] Depending on the non-zero extent, the scanning laser beam can be assigned a beam width b corresponding to the extent of the impact area perpendicular to the trajectory. As a result, the trajectories are spaced apart by an amount d, which is also taken into account in the control data. In contrast to the prior art, a distance d between the trajectories is chosen that is less than 50% of the beam width b of the beam, in this case 40%. The radiation power striking the build material in the impact area is not distributed homogeneously within the impact area. Rather, the radiation intensity should fluctuate, as explained below using Figures 2 to 4.

[0083] In Fig. 3, the radiation intensity has a Gaussian distribution with a maximum of the radiation intensity in the center; in Fig. 2, a so-called donut distribution, i.e., a local minimum in the center surrounded by a region of higher radiation intensity; and in Fig. 4, a so-called "top hat" distribution, i.e., an approximately constant radiation intensity that decreases towards the edge. Mixed forms are, of course, also possible. The exact form of the distribution is determined by the beam profile adjustment device 26. Preferably, the beam shaping device (beam profile adjustment device) can have at least one micro-optical element controllable by the control device. For example, the beam profile adjustment device can be a diffractive optical element (DOE). A diffractive optical element, e.g.A grating, for example, modifies the wavefront of an incident beam by locally modulating the phase and / or amplitude of the reflected or transmitted partial beams and can operate reflectively or transmissively. Further preferably, a beam combining device disclosed in WO 2020 / 099172 A1 can be used to adjust an intensity distribution (e.g., Gaussian, donut, or tophat).

[0084] Furthermore, the intensity distribution can also be generated by superimposing multiple laser beams, either from multiple independent laser sources or from a single laser source, with the beams being split into partial beams using a beam splitter, for example. A method proposed by nLIGHT, Vancouver, WA 98665, USA, is also conceivable. It uses a multiple fiber optic cable, allowing the distribution of the radiant power to be varied among the individual fibers.

[0085] Alternatively, the intensity distribution can be adjusted using liquid crystals (e.g., arranged in columns or pixels). Preferably, a distribution of the radiation intensity within the impact area is specified in the control data, for example, by specifying a corresponding control of the beam profile adjustment device in the control data, for example, also depending on the position of the build-up material layer to be scanned.

[0086] To achieve the desired anisotropic mechanical properties in the components, the distribution of the radiation intensity at the edge of the impact area should be adjusted so that it has a gradient of at least 1% per pm, preferably at least 2% per pm, more preferably at least 3% per pm, and most preferably at least 4% per pm. The definition of the gradient at the edge is schematically illustrated in Figures 2 to 4.

[0087] To avoid hot cracks, a beam diameter (extension of the impact area) of no more than 470 pm, preferably 420 pm, even more preferably 300 pm, and / or at least 30 pm, preferably 80 pm, even more preferably 200 pm should be used. The distance d between the trajectories should then be adjusted to the beam diameter b according to the specifications mentioned above.

[0088] The donut-shaped intensity distribution shown in Fig. 6 (in kW / cm 2) a diameter b of the impact area on the build material of 250 pm can be assigned, with the intensity decreasing by 3 to 4% per pm at least at one point in the impact area, particularly towards the edge of the impact area. With such an intensity distribution, cubes with an edge length of 10 mm were manufactured from CM247LC powder using an SLM process. The total power in the beam fluctuated between 350 W and 500 W, with the scanning speed along the trajectories being between 1000 and 2000 mm / s (with a layer thickness between 0.085 and 0.09 mm) and the distance d between two neighboring hatch lines being between 75 pm and 95 pm (the distance between two neighboring trajectories is correspondingly between 30% and 38% of the impact area). Furthermore, the trajectories were rotated by 90° in the build plane from layer to layer. With these parameters, a build rate of up to 3.8 mm was achieved. 3 / s. The inventors have observed that the crack density can be influenced, in particular reduced, by parameter combinations within the above-mentioned ranges.

[0089] To determine the crack density, a micrograph of the manufactured component can be analyzed using image analysis software (e.g. ImageJ), whereby the total length of the individual cracks is determined by adding up all branches and finally the total length (sum) of all cracks is put in relation to the total area of ​​the micrograph.

[0090] In a first study with a donut-shaped intensity distribution, process parameters as shown in Table 1 were tested. With the process parameters shown in Table 1, a crack density of 0.33 mm / mm 2The relationship between scanning speed and crack density was also investigated. It was found that by reducing the scanning speed from 1500 mm / s to 1000 mm / s, the crack density decreased from 0.33 mm / mm 2 to 0.11 mm / mm 2 can be reduced.

[0091] Table 1 :

[0092] In addition, for a parameter set as shown in Table 2, the hatch distance, scan speed, and laser power were changed, and the corresponding change in crack density was evaluated. The following was observed: - A reduction in the hatch distance from 90 pm to 84.6 pm (percent reduction in hatch distance: 6%) leads to an increase in crack density to 0.1 mm / mm 2 (percentage increase in crack density 18%). On the other hand, an increase in the hatch distance to 94.6 pm (percentage increase in hatch distance: 6%) also leads to an increase in crack density to 0.19 mm / mm2 (percentage increase in crack density 72%).

[0093] - A reduction of the scanning speed to 1000 mm / s (percent reduction of the scanning speed 11%) leads to an increase of the crack density to 0.19 mm / mm 2 (percentage increase in crack density: 129%). Increasing the scanning speed to 1249 mm / s (percentage increase in scanning speed: 11%) also leads to an increase in crack density to 0.1 mm / mm 2 (percentage increase in crack density: 18%).

[0094] - A reduction of the laser power to 410 W (percentage reduction: 7%) leads to an increase of the crack density to 0.083 mm / mm 2 (percentage increase in crack density: 3%). Increasing the laser power to 356 W (percentage increase in laser power: 7%) also leads to an increase in crack density to 0.16 mm / mm 2 (percentage increase in crack density: 18%).

[0095] Table 2:

[0096] The tophat-shaped intensity distribution shown in Fig. 7 (in kW / cm 2 ) a diameter b of the impact area on the build-up material of 250 pm can also be assigned, with the intensity decreasing at at least one point of the impact area, particularly towards the edge of the impact area, by 1.5 to 2% per pm. With such an intensity distribution, cubes with an edge length of 10 mm were again manufactured from CM247LC powder using an SLM process. The total power in the beam varied between 350 W and 433 W, with the

[0097] The scanning speed along the trajectories was between 1875 and 2167 mm / s (at a layer thickness between 0.075 and 0.09 mm), and the distance d between two adjacent hatch lines was between 65 and 90 pm. Furthermore, the trajectories were rotated by 90° in the build plane from layer to layer.

[0098] With the parameters mentioned, a build rate of up to 4.2 mm 3 / s. The crack density (determined by Image-J algorithms) was less than 0.15 mm / mm 2 In particular, further investigations investigated the change in crack density as a function of the change in hatch distance, scanning speed, and laser power. The parameters underlying these investigations are shown in Table 3. The inventors observed the following changes:

[0099] - A reduction of the hatch distance to 65.25 pm (percent reduction of the hatch distance: 13%) leads to an increase of the crack density to 0.18 mm / mm 2 (percentage increase in crack density 63%). On the other hand, an increase in the hatch distance to 84.75 pm (percentage increase in hatch distance: 13%) also leads to an increase in crack density to 0.21 mm / mm 2 (percentage increase in crack density 85%).

[0100] - A reduction of the scanning speed to 1743.75 mm / s (percent reduction of scanning speed: 7%) leads to an increase of the crack density to 0.16 mm / mm 2 (percentage increase in crack density: 44%). Increasing the scanning speed to 2006.25 mm / s (percentage increase in scanning speed, 7%) also leads to an increase in crack density to 0.15 mm / mm 2 (percentage increase in crack density 38%).

[0101] - A reduction of the laser power to 360.84 W (percent reduction: 7%) leads to an increase of the crack density to 0.17 mm / mm 2 (percentage increase in crack density: 48%). Increasing the laser power to 415.16 W (percentage increase in laser power: 7%) also leads to an increase in crack density to 0.13 mm / mm 2 (percentage increase in crack density: 14%).

[0102] Table 3:

[0103] The ramp distribution of intensity (in kW / cm 2) a diameter b of the impact area on the build material of 300 pm in the main extension direction and 80 pm in the direction perpendicular to the main direction can be assigned, with the intensity decreasing by 2.5 to 3.5% per pm at least at one point in the impact area, particularly towards an edge of the impact area. As shown in the figure, in the practical implementation of the ramp distribution, there can be secondary maxima in addition to the main maximum. With such an intensity distribution, cubes with an edge length of 10 mm were manufactured from CM247LC powder using an SLM process. The total power in the beam varied between 195 W and 350 W, with the scanning speed along the trajectories between 2500 mm / s and 3500 mm / s (at a layer thickness between 0.075 and 0.09 mm) and the distance d between two adjacent hatch lines between 40 and 70 pm.Furthermore, the trajectories were rotated by 90° in the build plane from layer to layer. Such a ramp-shaped intensity distribution exhibits a change in radiation intensity of up to 1.95% / pm.

[0104] With the parameters mentioned, a build rate of up to 4.2 mm 3 / s. The crack density (determined by Image-J algorithms) was less than 0.09 mm / mm 2 In particular, the change in crack density was investigated as a function of the change in hatch distance, scanning speed, and laser power. The parameters underlying these investigations are shown in Table 4. The inventors observed the following changes:

[0105] - A reduction of the hatch distance to 40.15 pm (percent reduction of the hatch distance: 27%) leads to an increase of the crack density to 0.25 mm / mm 2(percentage increase in crack density 165%). On the other hand, an increase in the hatch distance to 60 pm (percentage increase in hatch distance: 9%) also leads to an increase in crack density to 0.13 mm / mm 2 (percentage increase in crack density 38%).

[0106] - A reduction of the scanning speed to 2751 mm / s (percent reduction of scanning speed: 4%) leads to an increase of the crack density to 0.16 mm / mm 2 (percentage increase in crack density: 71%). Increasing the scanning speed to 2980 mm / s (percentage increase in scanning speed: 4%) also leads to an increase in crack density to 0.15 mm / mm 2 (percentage increase in crack density 71%).

[0107] A reduction of the laser power to 285 W (percent reduction: 5%) leads to an increase of the crack density to 0.30 mm / mm 2(percentage increase in crack density: 226%). Increasing the laser power to 315 W (percentage increase in laser power: 5%) also leads to an increase in crack density to 0.11 mm / mm 2 (percentage increase in crack density: 27)

[0108] Table 4:

[0109] The crack density is related to the crystal structure of the component. In particular, it can be assumed that the smaller the crack density, the larger and the more strongly oriented the grains (crystals) are. In order to determine the correlation between process parameters and the microstructure or crystal structure of the component (also called texture) more precisely, the invention specifically investigated the influence of the process parameters (radiation intensity, change in radiation intensity within the impact area, diameter of the impact area or width of the scan line, scan speed, hatch distance) on the texture properties of the component resulting from the manufacturing process. Texture properties include the proportion of large-angle grain boundaries (angle of orientation between neighboring crystal regions), grain orientation relative to a vertical plane of the layer, and maximum grain dimensions (e.g.,relative to the hatch distance between adjacent trajectories), extension of the grains (e.g. relative to the hatch distance between adjacent trajectories) in the direction perpendicular to the layer or build direction of the component.

[0110] The inventors have observed that the maximum dimension of the grains and the extension of the grains in the direction perpendicular to the plane of the layer increase along with the change in the radiation intensity in the impact region (i.e., the greater the change in the radiation intensity in the impact region (in particular, the steeper the radiation intensity drops towards the edge of the impact region), the larger the maximum dimension of the grains and the greater the extension of the grains in a plane perpendicular to the layer). A greater extension of the grains in a plane perpendicular to the layer also means that the proportion of large-angle grain boundaries is smaller: the more the grains are oriented perpendicular to the layer, the smaller the angle between neighboring grains and the smaller the proportion of grain angle boundaries that deviate from this small angle.The fact that the grains are highly expanded perpendicular to the layer also means that they are essentially oriented perpendicular to the layer. In particular, the direction in which the grains exhibit their maximum dimension forms an angle of no more than 15° with a perpendicular to the layer.

[0111] The aforementioned properties of the grains or their texture (proportion of large-angle grain boundaries, orientation of the grains relative to a perpendicular plane of the layer, maximum grain dimensions, grain extension in the direction perpendicular to the layer or the component's construction direction) also depend on the hatch distance and the diameter of the impact area or the beam width. Preferably, the radiation intensity and scan speed, in combination with the other parameters, should be within specific intervals in order to achieve the desired grain properties in combination with the inventive change in radiation intensity.

[0112] Table 5:

[0113] The fact that the proportion of high-angle grain boundaries is less than 33% means that the orientation angle of the grains relative to the perpendicular to the layer is essentially a maximum of 15°. As explained above, a larger angle of the grains relative to the perpendicular to the layer decreases the angle between the different grains, thus reducing the proportion of high-angle grain boundaries in the material.

[0114] The maximum dimension of the grains is typically larger than the extension of the grains perpendicular to the layer, because the maximum extension of a grain lies in a direction other than the direction perpendicular to the layer. However, the larger the extension of the grains perpendicular to the layer, the smaller the difference between the extensions of the grains perpendicular to the layer and the maximum dimension of the grains. For this reason, the maximum dimension (the maximum diameter) of the grains (crystallites in the manufactured object) and the extension of the grains perpendicular to the layer (related to the orientation of the component during the manufacturing process) are in the same range (see Table 5), even if the maximum dimension of the grains is generally slightly larger than their extension perpendicular to the layer.

[0115] In combination with the change in radiation intensity shown in Table 5, the other parameters should preferably be in the following intervals:

[0116] Radiation intensity: between 40 and 450 W.

[0117] Hatch distance: between 50-125 pm

[0118] Diameter of the impact area: between 30 and 400 pm Scanning speed: between 1000 mm / s and 3500 mm / s

[0119] For the minimum change in radiation intensity towards the edge of the impact area, a smaller value can be selected, e.g. a value between 1.5% / pm and 2% / pm, if more than 75% of the radiation power is distributed over half the area of ​​the impact area, as is the case with a TopHat profile.

Claims

Patent claims 1. A method for adjusting the radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy by a beam to those locations of the layer that are associated with the cross-section of the component in this layer, by moving the beam (22) along a plurality of trajectories in the cross-section of the component by means of a preferably controllable beam movement device in order to melt the build-up material at the locations that are associated with the cross-section of the component, and wherein the radiation intensity of the beam is adjusted using a beam profile adjustment device within an impact area of the beam on the build-up material, characterized in thatthat the radiation intensity of the beam is adjusted so that its distribution in the area of impact of the beam on the building material changes by at least 1% per pm at at least one point.

2. Method according to claim 1, in which the radiation intensity is adjusted such that its distribution in the area of impact of the beam on the building material at at least one point towards the edge of the impact area decreases by at least 1% per pm, preferably at least 2% per pm, more preferably at least 3% per pm, most preferably at least 4% per pm, and / or in which the radiation intensity is adjusted such that its distribution at the at least one point towards the edge of the impact area decreases by at most 5% per pm, more preferably at most 7% per pm, more preferably at most 9% per pm.

3. Method according to claim 2, in which the radiation intensity is adjusted so that its distribution in the area of impact on the building material varies so that in the case of rotation of the beam at least one point of the layer Decrease in radiation intensity towards the edge of the impact area and / or the position of the impact area with respect to the location of the layer changes.

4. Method according to one of the preceding claims, wherein the radiation intensity is adjusted such that at least 90%, preferably at least 95%, particularly preferably at least 99%, of the total radiation power is distributed within an impact region of the beam on the building material, the diameter of which is at most 470 pm, more preferably 420 pm, even more preferably 300 pm, and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

5. Method according to one of the preceding claims, in which the radiation intensity is adjusted such that, starting from a point on the trajectory lying within the impact region, the distribution of the radiation intensity in the impact region of the beam on the building material has a different extent in a direction perpendicular to the trajectory than in the direction opposite to this perpendicular direction.

6. Method according to one of the preceding claims, wherein the beam movement device is controllable and is controlled such that the distance between two adjacent trajectories which run substantially parallel to one another is less than or equal to 50% of the beam width of the beam, preferably less than or equal to 35% of the beam width and greater than or equal to 15% of the beam width.

7. Method according to one of the preceding claims, wherein the beam movement device is controllable and is controlled such that the beam is moved along a trajectory at a speed which is greater than or equal to 1 m / s.

8. Additive manufacturing method for the additive production of a three-dimensional component (2) by means of an additive manufacturing device, wherein in the additive manufacturing process a method for adjusting a radiation intensity of a beam according to one of the preceding claims is carried out.

9. Additive manufacturing method according to claim 8, wherein the variation of the radiation intensity in the impact region on the build-up material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that after cooling of the previously melted build-up material, the proportion of large-angle grain boundaries is less than 75%, preferably less than 66%, more preferably less than 50%, most preferably less than 33%.

10. Additive manufacturing method according to one of claims 8 or 9, wherein the variation of the radiation intensity in the area of impact on the building material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that after cooling of the previously melted building material, the orientation of the grains relative to a perpendicular to the plane of the layer is a maximum of 15°.

11. Additive manufacturing method according to one of claims 8 to 10, wherein the variation of the radiation intensity in the impact area on the building material, the speed at which the beam is moved along the plurality of trajectories, and the distance between adjacent trajectories are selected such that after cooling of the previously melted building material, the maximum dimension of the grains is greater than or equal to 20 times, preferably greater than or equal to 50 times, even more preferably greater than or equal to 100 times, the distance between two adjacent trajectories.

12. Additive manufacturing method according to one of claims 8 to 11, in which the variation of the radiation intensity in the area of impact on the building material, the speed with which the beam is moved along the plurality of trajectories, the distance between adjacent trajectories are selected such that after the cooling of the previously melted building material, the extension of the grains perpendicular to the planes of the layers is greater than or equal to 20 times, preferably greater than or equal to 50 times, more preferably greater than or equal to 100 times, the distance between two adjacent trajectories.

13. Additive manufacturing method according to one of claims 9 to 12, wherein the directions of superimposed trajectories in successive layers are rotated relative to one another by an angle which is substantially 90°, preferably exactly 90°.

14. A computer-aided method for generating control command data for adjusting the radiation intensity of a beam in a manufacturing process for the additive manufacturing of a component, wherein components are produced in the manufacturing process by applying a build-up material layer upon layer and solidifying it in each applied layer by supplying radiation energy by a beam to those locations of the layer that are associated with the cross-section of the component in this layer, by moving the beam along a plurality of trajectories in the cross-section of the component by means of a preferably controllable beam movement device in order to melt the build-up material at the locations that are associated with the cross-section of the component, wherein the radiation intensity of the beam is adjusted using a beam profile adjustment device within an impact area of the beam on the construction field,and wherein the control command data are used to control the beam profile adjustment device, characterized in that the control command data are generated such that a distribution of the radiation intensity in the area of incidence of the beam on the building material changes at least at one point by at least 1% per pm and / or that at least 90%, preferably 95%, particularly preferably 99%, of the total radiation power is distributed within an area of incidence of the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm.

15. Beam profile adjustment device for generating a beam in a manufacturing process for the additive manufacturing of a component, wherein in the manufacturing process components are produced by applying a building material layer upon layer and solidifying it in each applied layer by supplying radiation energy to those locations of the layer that are assigned to the cross-section of the component in this layer, wherein the beam profile adjustment device is designed to adjust the distribution of a radiation intensity within an impact area of the beam, characterized in that the beam profile adjustment device generates the beam such that the radiation intensity in the impact area of the beam on the building material changes at least at one location by at least 1% per pm and / or that at least 90%, preferably 95%, particularly preferably 99%,the total radiation power is distributed within an impact area of the beam on the building material, the diameter of which is at most 300 pm, more preferably 420 pm, even more preferably 470 pm and / or at least 30 pm, more preferably 80 pm, even more preferably 200 pm., 16. Additive manufacturing device for producing a three-dimensional object with an application device for applying a building material layer upon layer and an energy input device for supplying radiation energy by a beam to those locations of a layer which are assigned to the cross-section of the object in this layer, which has: a beam profile device for adjusting a radiation intensity of the beam and a beam movement device for moving the beam along a plurality of trajectories, wherein the building material is melted at the locations which are assigned to the cross-section of the component in the layer along the trajectories, characterized in that the beam profile device adjusts the radiation intensity of the beam such that the radiation intensity in The area of impact of the beam on the build-up material changes by at least 1% per pm at least in one place.

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