Method for producing a component by means of an additive manufacturing method using an energy beam

Abstract

The invention relates to a method and a device (100) for producing a component (102) by means of an additive manufacturing method using an energy beam (114). The method comprises the steps of (a) providing a powder, (b) applying at least one first powder layer (110a) of the powder (110) to a construction platform (106) of a process chamber (104), (c) defining a target contour (120) of the component (102), wherein the target contour comprises a plurality of solid layers of the component (102), (d) melting at least one first predetermined region (116a) of the applied first powder layer (110a) by means of an energy beam (114) in such a way that the first predetermined region (116a) is transferred into a first solid layer (118a), (e) melting at least one second predetermined region (116b) of the applied first power layer (110a) by means of the energy beam (114) in such a way that a melt bath (122) of the melted powder (110) is produced, (f) calculating at least one transport vector (123) of the energy beam (114) depending on the target contour (120) of the component (102), and (g) moving the energy beam (114) according to a scanning vector (124) in such a way that melted material from the melt bath is guided, according to the calculated transport vector (123), from an actual position (125) to a target position (126) on or at the first solid layer (118a) in accordance with the target contour (120) and / or the second predetermined region is transferred into a solid layer region (133a) of the first solid layer (118a) in accordance with the target contour (120).

Description

[0001] Method for producing a component by means of an additive manufacturing process using an energy beam

[0002] Technical area

[0003] The present invention relates to a method for producing a component by means of an additive manufacturing process using an energy beam.

[0004] Technical background

[0005] Additive manufacturing is a process in which a component is built layer by layering material based on digital 3D design data. Additive manufacturing is a professional production process that differs significantly from conventional, subtractive manufacturing methods. Instead of milling a workpiece from a solid block, for example, additive manufacturing builds components layer by layer from materials that are in the form of a fine powder, for example.

[0006] Additive manufacturing processes include selective electron beam melting, selective laser sintering, and selective laser melting. In this process, a build surface is successively coated with a specific powder, such as metal powder, which is melted using a laser or electron beam. By melting the metal powder layer by layer and then solidifying it upon cooling, a component is created by stacking and bonding several individual layers. This allows complex structures and three-dimensional geometries to be realized, which can be manufactured in a single step and without the use of a geometric or physical tool.In selective electron beam melting, the beam can be virtually divided into several partial beams, each of which has an n-th of the power, because no mass-bearing parts (mirrors, lenses) are required to move the electron beam, as is the case with a laser beam.

[0007] DE 102 08 150 B4 discloses a method and a device for producing a shaped body.

[0008] WO 2019 / 092238 A1 discloses a method and a device for layer-by-layer additive manufacturing of components using a continuous and a pulsed laser beam and associated computer program product.

[0009] Despite the numerous advantages of state-of-the-art powder bed-based additive manufacturing processes, there is still room for improvement. Layer thicknesses are typically in the range of 10 pm to 200 pm, typically around 50 pm. The in-plane resolution / positioning accuracy of the laser is typically more than an order of magnitude better (around 5 pm and finer) than the layer thickness. The resolution of today's laser scanners is typically 16, 20, or 24 bit, with typical build chamber footprints ranging from 50*50 mm to 800*800 mm, usually 150*150 to 350*350 mm. The resolution in the build direction, i.e., layer thickness, cannot be arbitrarily reduced. The reasons for this are, on the one hand, the increasing process time with an increase in the number of layers per height unit, and, on the other hand, the fine powder required.Very fine powder has the disadvantage of poor flow properties (interparticle forces in the powder increase disproportionately to the weight as the powder becomes finer) when applying the powder layer, is easily dispersed, and, due to its large surface area, introduces a high hydrogen and oxygen content into the material. This leads to cold cracking and a permanent reduction in the material's ductility. Furthermore, fine powder would be dispersed by the evaporation pressure of the laser, at a corresponding power or power density, requiring a reduction in power, resulting in even longer process times and thus additional costs.

[0010] For steep component sections, the actual and perceived resolution is therefore very good because the edge contours in the respective layer can be exposed with high precision. The discretization error resulting from the finite layer thickness, colloquially known as the stair-step effect, increases with increasing layer thickness and a flatter contour. In very flat areas, however, the edge contours are very far apart due to the angle and layer thickness. The steps are therefore particularly noticeable. This "negative" appearance is exacerbated by the fact that successive layers are usually scanned or exposed with different scan patterns. If the scan patterns protrude below the next layer, the image is perceived by the viewer as additionally disturbing due to the usually different scanning direction and often does not meet aesthetic requirements.

[0011] Depending on the geometric accuracy and surface requirements, a component is therefore not finished after additive manufacturing and requires post-processing. In addition, post-processing is not always possible or economical. Additive manufacturing allows the production of components that would otherwise not be manufacturable. This means that post-processing is not possible in many places. For example, internal cooling channels cannot be post-processed conventionally. Even if post-processing is not possible, particularly due to a lack of accessibility, various applications (e.g. toolmaking) expect the component to have a certain contour and surface that cannot be achieved due to the insufficient resolution in the known solutions.

[0012] Object of the invention

[0013] It would therefore be desirable to provide a method for producing a component using an additive manufacturing process using an energy beam or electron beam, which at least largely avoids the disadvantages of known additive manufacturing processes. In particular, the invention is intended to enable the production of components with a higher resolution, so that the printed actual geometry is almost identical to the target geometry and / or a defined surface structure is created. Contour-close manufacturing should eliminate post-processing steps, thus enabling a faster additive manufacturing process chain.

[0014] General description of the invention

[0015] This problem is addressed by a method for producing a component by means of an additive manufacturing process using an energy beam with the features of the independent patent claim. Advantageous further developments, which can be implemented individually or in any combination, are presented in the dependent claims.

[0016] In the following, the terms "have", "have", "comprise" or "include" or any grammatical variations thereof are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, apart from the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression "A has B", "A has B", "A comprises B" or "A includes B" can refer both to the situation in which, apart from B, no further element is present in A (i.e., a situation in which A consists exclusively of B), and to the situation in which, in addition to B, one or more further elements are present in A, for example element C, elements C and D, or even further elements.

[0017] Furthermore, it should be noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be provided singly or multiple times, are generally used only once, for example, when the feature or element is first introduced. When the feature or element is subsequently mentioned again, the corresponding term "at least one" or "one or more" is generally no longer used, without limiting the possibility that the feature or element may be provided singly or multiple times.

[0018] Furthermore, the terms “preferably”, “in particular”, “for example” or similar terms are used hereinafter in connection with optional features, without limiting alternative embodiments. Thus, features introduced by these terms are optional features, and these features are not intended to limit the scope of the claims, and in particular the independent claims. Thus, as those skilled in the art will recognize, the invention can also be carried out using other embodiments. Similarly, features introduced by “in one embodiment of the invention” or by “in an embodiment of the invention” are understood as optional features, without limiting alternative embodiments or the scope of the independent claims.Furthermore, these introductory expressions are intended to leave untouched all possibilities of combining the features introduced thereby with other features, whether optional or non-optional.

[0019] In a first aspect, a method for producing a component by means of an additive manufacturing process using an energy beam is proposed. The method comprises at least the following steps:

[0020] (a) Providing a powder,

[0021] (b) applying at least a first powder layer of the powder to a build platform of a process chamber,

[0022] (c) defining a target contour of the component, wherein the target contour comprises several solid layers of the component,

[0023] (d) melting at least a first predetermined region of the applied first powder layer by means of an energy beam such that the first predetermined region is converted into a first solid layer,

[0024] (e) melting at least a second predetermined region of the applied first powder layer by means of the energy beam in such a way that a melt pool of the molten powder is formed,

[0025] (f) Calculating at least one transport vector of the energy beam as a function of the desired contour of the component, and

[0026] (g) moving the energy beam according to the calculated scan vector such that molten material from the melt pool is moved from an actual position to a desired position on or at the first fixed layer corresponding to the desired contour and / or the second predetermined region is transferred into a fixed layer region of the first fixed layer corresponding to the desired contour.

[0027] It is explicitly emphasized that the steps mentioned can be performed in the specified order or in a different order. Furthermore, one or more steps may be repeated.

[0028] Thus, the method according to the invention makes it possible to achieve a match between a target and an actual geometry through targeted beam-induced material transport and / or adaptation of operating parameters of the energy beam. In particular, the method makes it possible to avoid elevations and depressions or to create remelted areas that are as flat as possible, as well as to create contour-accurate remelted areas inclined towards the powder bed surface when the component cross-section tapers and widens, i.e., to compensate for contour differences between layers. In contrast to conventional additive manufacturing processes, the definition of the target contour and the adjustment of the energy beam parameters are not discretized for each layer separately and independently of one another, but rather take adjacent layers into account in order to create transitions between the layers.

[0029] The scan vector can include at least one movement component of the energy beam away from the target position. The molten powder or material already melted into a solid by prior melting can be moved from the melt pool in the opposite direction to the movement component. The method specifically exploits the fact that material from the melt pool can be transported in the opposite direction to the direction of movement of the energy beam.

[0030] The scan vector can include at least one start and one end point for the movement of the energy beam. By planning or executing a coherent set of beam parameters, scan paths, in particular stop and start points, their execution sequence and number, a predefined surface geometry is achieved for each build level within a predefined tolerance in additive manufacturing using the powder bed process, such as selective energy beam melting or selective electron beam melting. The surface geometry results from the geometry of the component to be manufactured. This particularly concerns the areas of the component that must be exposed in one level but are not exposed in the subsequent level because they form the surface of the component.

[0031] The scan vector can be varied relative to the calculated transport vector. For example, when transporting from a maximum or elevation to a minimum or depression, it may be advantageous to slightly vary the start and stop positions laterally and along the direction to avoid the formation of excessively localized material transport and achieve uniform transport.

[0032] The transport vector can be calculated based on look-up tables, artificial intelligence, measured values, simulation, and / or deterministic calculations. This allows for adaptive trajectory planning for the movement of the energy beam, allowing adjustments to be made as quickly as possible. The beam parameters of the energy beam or electron beam can vary along the length of the vector to achieve material release or uptake through variation. Enlarging the vapor pressure capillary or dent leads to a relative release of material, while decreasing it leads to uptake. Continuous variation allows for consistent trajectories to be achieved.

[0033] The second predetermined area can at least partially surround the first solid layer or border it. Depending on the gradient of the geometry (inclination of the surface), locally varying thicknesses of the additional material (shell) can be melted and converted from the powdered to the solid state, and then processed or transported to achieve the desired inclination at that location. The two cases can be combined so that protrusions are avoided in each build plane in the "interior" of the component, thus making the exposed layer as flat as possible and achieving the appropriate angles or inclinations in the edge area. Even unwanted elevations caused by splashes, i.e., material ejected from the process zone that has bonded to the surface, can be removed or distributed across the surface.

[0034] The method may further comprise applying at least a second powder layer of the powder to the first solid layer, melting at least a first predetermined region of the applied second powder layer using the energy beam such that the first predetermined region of the applied second powder layer is converted into a second solid layer, wherein the target position is adjacent to the second solid layer. Thus, material can be transported in a targeted manner from one layer level to another, for example, to form a transition between the layers.

[0035] The second solid layer may have a smaller extension than the first solid layer, at least in a direction parallel to a surface facing the first solid layer. Thus, the component tapers when viewed from above.

[0036] The method can further comprise applying at least a second powder layer of the powder to the first solid layer and displacing the solid layer region of the powder of the first powder, melting at least a first predetermined region of the applied second powder layer by means of the energy beam such that the first predetermined region of the applied second powder layer is converted into a second solid layer, melting a second predetermined region of the second solid powder layer and partially melting the second predetermined region of the powder of the first powder layer such that the second predetermined region of the second powder layer is converted into a solid layer region of the second solid layer corresponding to the desired contour and the second predetermined region of the first powder layer is converted into the solid layer region of the first solid layer corresponding to the desired contour.

[0037] Even for components where material transport cannot be used as before to create the contour with sublayer resolution, i.e., with a resolution smaller than the layer thickness, the energy beam can vary during expansion, as in the case of tapering. This means that sublayers can also be created with targeted variation of the scan vectors, multiple exposures, and different / adaptive energy input.

[0038] At least in a direction parallel to a surface facing the first solid layer, they extend beyond the first solid layer, or they locally project beyond the first layer, thus forming an overhang. Thus, when viewed from above, the component expands at least locally. In other words, the upper layer can not only cover the underlying layer, but its projection can also exceed the contour of the lower layer, and thus, parts of the contour of the upper layer can be found above unmelted powder.

[0039] The molten powder from the melt pool can be moved to the desired position and / or transferred into the fixed layer area in such a way that it is transformed into a fixed desired shape. This creates a fixed contour. The key mechanism for achieving higher resolution is that the parameters of the energy beam are not kept constant, but can be changed depending on the distance between the edges of adjacent layers.

[0040] The target shape can form or define a transition, particularly a smooth transition, between the first solid layer and the second solid layer. This allows a target contour with a transition between the layers to be realized without any post-processing.

[0041] The amount of molten material moved to the target position from the melt pool or a mold of the solid layer region of the first solid layer can be adjusted by multiple meltings, in particular 1 to 1000 meltings, using the energy beam, adjusting a scan length of the energy beam, adjusting the direction of movement of the energy beam, a speed, an acceleration, a focus position, a power of the energy beam, and / or a distance between scan vectors of the energy beam. This allows the required amount of material to be transported to be precisely adjusted.

[0042] To adjust the amount of molten material moved from the melt pool to the target position or the shape of the solid layer region of the first solid layer, the energy beam power, speed, acceleration, and / or focus position of the energy beam can be varied during the scan vector. Accordingly, by adjusting the energy beam parameters, the adaptation to the target contour can be specifically adjusted by adjusting the amount of molten powder.

[0043] The method can further comprise measuring an actual surface of the first solid layer, determining locations on the first solid layer with deviations from a desired shape, determining correction scan vectors for the locations on the first solid layer with deviations from a desired shape, melting the locations on the first solid layer with deviations from the desired shape using the energy beam, and moving the energy beam according to the correction vectors such that molten material at the locations is moved to a desired correction position on or at the first solid layer. This allows the detection of previously undesired material protrusions above the desired surface, e.g. caused by splashes, undesired material transport during the initial exposure, warping, and the like.

[0044] The deviations can include elevations and / or depressions. This allows a smooth or even surface to be achieved without any post-processing.

[0045] The actual surface can be measured using a 3D scanner, optical coherence tomography, photogrammetry, and / or digital image correlation. This allows for precise measurements.

[0046] The method can further include measuring and / or estimating the effective depth, shape, and / or dimensions of the melt pool. The energy beam creates a melt pool whose depth depends on several factors, such as energy input or the temperature of the powder or previously remelted material (previous melt pool). However, the melt pool influences not only the powder layer to be melted, but also the layers below it. By determining the effective depth, the number of layers can be specifically influenced to achieve the required target contour. The effective depth, shape, and / or dimensions of the melt pool can be measured using a 3D scanner, optical coherence tomography, photogrammetry, and / or digital image correlation. This allows for precise determination of the melt pool properties.

[0047] The process may further include calibrating the energy beam prior to melting, whereby the calibration results can be incorporated into the scan vector calculation. To ensure optimal targeted material transport, a calibration process is preferably used. Calibration can be combined with all of the process variations presented here. This allows the properties of the powder, machine, and environment to be determined. Using the collected information, an optimized path plan can be calculated in advance during the initial path planning, allowing the material transport to be used in a targeted manner.

[0048] The target contour can comprise an angle between parallel edges of two superimposed solid layers in a range of less than 45°, preferably less than 35°, and even more preferably less than 25°. This makes the process particularly suitable for relatively flat component contours.

[0049] The at least one applied first powder layer can have a thickness of 5 μm to 1 mm, preferably 30 μm to 0.8 mm, and even more preferably 50 μm to 0.7 mm. This allows adjustments to the desired contour with a resolution below the layer thickness, despite the usual layer bead.

[0050] The powder can have an average diameter d50 of 10 pm to 1 mm, and preferably 30 pm to 200 pm. This allows the use of conventional powders.

[0051] The transport length from the actual position to the target position can be in a range of 0.1 mm to 1.0 mm, and preferably 0.2 mm to 1.0 mm. This allows for material transport in dimensions that exceed the layer thickness.

[0052] One or more steps of the process are repeated, especially multiple times. This allows the component to be built up layer by layer.

[0053] The energy beam can be a laser beam and / or an electron beam. Accordingly, the process can be adapted for various additive manufacturing processes. The process can be computer-implemented, allowing the process to be implemented effectively and cost-effectively.

[0054] In a further aspect, a device for producing a component by means of an additive manufacturing process using an energy beam or an electron beam is proposed. The device comprises: a process chamber with a build platform, an application device, in particular a squeegee, for applying a powder layer to the build platform, at least one energy beam source for emitting an energy beam onto the powder layer, a deflection unit for deflecting the energy beam, in particular a scanner having two mirrors and a focusing device consisting of optical lenses, or a deflection unit consisting of capacitor plates and a focusing device, wherein the device is designed to carry out a method according to one of the embodiments described herein.

[0055] The term “additive manufacturing,” as used herein, is a broad term that should be given its ordinary and common meaning as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a manufacturing process in which material is deposited layer by layer to create three-dimensional objects (workpieces). The layer-by-layer construction is computer-controlled from one or more liquid or solid materials according to predetermined dimensions and shapes. Physical or chemical curing or melting processes take place during the construction process. Additive manufacturing is also known as 3D printing. Typical materials for 3D printing are plastics, synthetic resins, ceramics, and specially processed metals. Carbon and graphite materials have also been developed for the 3D printing of carbon parts.Although these are often forming processes, no special tools that store the respective geometry of the workpiece (e.g., casting molds) are required for a specific product. It should be noted that in the variant of the method according to the invention in which material is transported from an actual position to the desired position, only materials that are meltable and in which a vapor pressure capillary is formed by the energy beam can be used. A particularly advantageous application of the method of the present invention is powder bed-based melting. Powder bed-based melting processes include additive manufacturing processes in which thermal energy selectively joins or fuses regions of a powder bed. This category includes, among others, energy beam melting, electron beam melting, laser melting, and laser sintering.

[0056] In selective energy beam melting, the material to be processed is applied in powder form in a thin layer to a base plate. The powdered material is completely melted locally using energy radiation and, after solidification, forms a solid layer of material. The base plate is then lowered by the amount of one layer thickness and more powder is applied. This cycle is repeated until all layers have been remelted. The finished component is cleaned of excess powder, processed as required, or used immediately. The layer thicknesses typical for the construction of the component range between 15 and 500 pm for all materials. The data for guiding the energy beam is generated from a 3D CAD body using software. In the first calculation step, the component is divided into individual layers.In the second calculation step, the paths (vectors) that the energy beam will follow are generated for each layer. To avoid contamination of the material with oxygen, the process takes place under a protective gas atmosphere of argon or nitrogen. Components manufactured using selective energy beam melting are characterized by high specific densities (> 99%). This ensures that the mechanical properties of the additively manufactured component largely correspond to those of the conventionally manufactured material. However, a component with selective densities can also be manufactured specifically, based on bionic principles or to ensure a partial elastic modulus. In lightweight construction in the aerospace industry and for body implants, such selective elasticities within a component are often desired and cannot be produced using conventional methods.Compared to conventional processes (casting processes), energy beam melting is characterized by the fact that tools or molds are not required (formless production), thus reducing time to market. A further advantage is the great geometric freedom, which enables the production of component shapes that are impossible or only possible with great effort using mold-based processes. Furthermore, storage costs can be reduced, as specific components do not have to be stored but can be manufactured additively on demand. In general, the higher the energy beam power, the higher the layer thickness used, and the greater the roughness of the component. Modern system technology can control density and surface quality according to the "shell-core principle". The segmented exposure specifically influences the outer areas of the component, overhangs, and high-density component areas.An optimized exposure strategy improves both the quality level and build speeds. The performance profile of a component can be significantly enhanced with the help of segmented exposure.

[0057] The term "layer" as used herein is a broad term to which its ordinary and customary meaning should be given, as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term may, without limitation, refer in particular to a flat, spread-out mass of a substance disposed above, below, or between something else. Accordingly, a layer has a width and length that are significantly greater than its height, for example by at least a factor of 5, preferably by at least a factor of 10, and even more preferably by at least a factor of 20, such as at least a factor of 100.

[0058] The term "powder," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to matter or material consisting of many small, solid particles such as grains or spheres. Examples of this state are granular materials such as plastic granules, and powdered materials such as metals, alloys, and powders. The particles can have a size or diameter of less than 100 pm (0.1 millimeters) to more than 1 mm, for example, from 10 pm to 5 mm. To achieve high bulk densities on the one hand and the economical production of the powders on the other hand, powders with a certain range of particle sizes are typically used, e.g. 10-30pm, 15-45pm, 20 to 63pm, 30 to 100pm, 60-200pm, 100-300pm, 200-600pm.Possible visibility thicknesses are then e.g. 15-40pm, 20- 60pm, 40-80pm, 40-100pm, 60-120pm, 100-180pm, 150-250pm, 200-400pm, 300- 1000pm.

[0059] The term “predetermined region” as used herein is a broad term which should be given its ordinary and common meaning as understood by those skilled in the art. The term is not limited to a specific or adapted meaning. The term can, without limitation, refer in particular to an area or section with a predefined dimension or size. The term “target contour” as used herein is a broad term which should be given its ordinary and common meaning as understood by those skilled in the art. The term is not limited to a specific or adapted meaning. The term can, without limitation, refer in particular to a desired external shape of the component to be manufactured. In particular, the target contour comprises the external shape of several layers of the component to be manufactured.

[0060] The term "vector," as used here, is a broad term to which its ordinary and common meaning should be given, as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a mathematical object that describes a parallel translation in a plane or in space. Vectors are defined by their length and direction, thus indicating the distance and direction by which a point is translated.

[0061] The term "transport vector," as used herein, is a broad term that should be given its ordinary and common meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can refer, without limitation, specifically to a vector that describes the transport of material, and in particular, its direction.

[0062] The term “scan vector,” as used here, is a broad term that should be given its ordinary and common meaning as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a vector that describes a parallel displacement of the energy beam in a plane or in space and thus defines orientation for exposure by the energy beam. The term can also be understood as a synonym for scan path if it is not a straight movement from point A to point B but a curved path. Curved paths can be defined, for example, by circular path segments, splines, polynomials, solutions of functionals or differential equations, etc.

[0063] The term "target position," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can refer, without limitation, in particular to a position or location to which molten powder material is to be specifically and deliberately transported in order to form a desired shape or contour there through deposition and solidification.

[0064] The term metal shall include: Typical industrially used metals and alloys containing both metals and semi-metals, alkali metals, and other alloying elements. In particular, steels in the sense of iron-carbon with nickel contents of 0-30%, chromium 0-30%, manganese 0-10%, silicon 0-5%, nickel-based alloys with nickel contents greater than 50%, titanium alloys with aluminum contents of 0-10% and vanadium contents of 0-10%, aluminum alloys with magnesium contents of 0-10% and silicon contents of 0-20%, magnesium alloys, tantalum alloys, tungsten alloys, copper alloys.

[0065] Furthermore, within the scope of the present invention, a computer program is proposed which, when run on a computer or computer network, executes the method according to the invention in one of its embodiments.

[0066] Furthermore, within the scope of the present invention, a computer program with program code means is proposed for carrying out the inventive method in one of its embodiments when the program is executed on a computer or computer network. In particular, the program code means can be stored on a computer-readable data carrier and / or a computer-readable storage medium.

[0067] The terms "computer-readable medium" and "computer-readable storage medium," as used herein, may refer in particular to non-transitory data storage devices, such as a hardware data storage medium on which computer-executable instructions are stored. The computer-readable medium or the computer-readable storage medium may, in particular, be or include a storage medium such as a random-access memory (RAM) and / or a read-only memory (ROM).

[0068] Furthermore, within the scope of the present invention, a data carrier is proposed on which a data structure is stored which, after being loaded into a working and / or main memory of a computer or computer network, can execute the inventive method in one of its embodiments. Furthermore, within the scope of the present invention, a non-transient computer-readable medium is proposed, comprising instructions which, when executed by one or more processors, cause the one or more processors to execute the inventive method in one of its embodiments.

[0069] Also proposed within the scope of the present invention is a computer program product with program code means stored on a machine-readable carrier in order to carry out the method according to the invention in one of its embodiments when the program is executed on a computer or computer network.

[0070] A computer program product is understood as a tradable product. It can, in principle, exist in any form, for example, on paper or a computer-readable data carrier, and can, in particular, be distributed via a data transmission network.

[0071] Finally, within the scope of the present invention, a modulated data signal is proposed which contains instructions executable by a computer system or computer network for carrying out a method according to one of the described embodiments.

[0072] With regard to the computer-implemented aspects of the invention, one, several, or even all method steps of the method according to one or more of the embodiments proposed here can be performed by means of a computer or computer network. Thus, in general, any of the method steps, including the provision and / or manipulation of data, can be performed by means of a computer or computer network. In general, these steps can comprise any of the method steps, excluding the steps that require manual work, for example, the provision of samples and / or certain aspects of performing actual measurements.

[0073] Finally, within the scope of the present invention, a data carrier is proposed with instructions which, when executed on an additive manufacturing device, cause the additive manufacturing device to produce a component according to a method according to one of the described embodiments. Finally, within the scope of the present invention, a print data set is proposed comprising information which, when made available to an additive manufacturing device, cause the additive manufacturing device to produce a component according to a method according to one of the described embodiments.

[0074] Finally, within the scope of the present invention, a computer program is proposed comprising instructions which, when the computer program is executed on a computer, cause the computer to generate a print data set according to the preceding embodiment.

[0075] In summary, without limiting further possible embodiments, the following embodiments are proposed:

[0076] Embodiment 1: Method for producing a component by means of an additive manufacturing process using an energy beam, comprising the steps:

[0077] (a) Providing a powder,

[0078] (b) applying at least a first powder layer of the powder to a build platform of a process chamber,

[0079] (c) defining a target contour of the component, wherein the target contour comprises several solid layers of the component,

[0080] (d) melting at least a first predetermined region of the applied first powder layer by means of an energy beam such that the first predetermined region is converted into a first solid layer,

[0081] (e) melting at least a second predetermined region of the applied first powder layer by means of the energy beam in such a way that a melt pool of the molten powder is formed,

[0082] (f) Calculating at least one transport vector of the electron beam as a function of the desired contour of the component, and

[0083] (g) Moving the energy beam according to a scan vector such that molten material from the melt pool is moved according to the calculated transport vector from an actual position to a target position on or at the first fixed layer corresponding to the target contour and / or the second predetermined region is transferred into a fixed layer region of the first fixed layer corresponding to the target contour. Embodiment 2: Method according to the preceding embodiment, wherein the scan vector comprises at least one movement component of the energy beam away from the target position, wherein the molten material from the melt pool is moved counter to the movement component.

[0084] Embodiment 3: Method according to one of the preceding embodiments, wherein the scan vector comprises at least one start point and one end point for the movement of the energy beam.

[0085] Embodiment 4: Method according to one of the preceding embodiments, wherein the scan vector is varied relative to the calculated transport vector.

[0086] Embodiment 5: Method according to one of the preceding embodiments, wherein the transport vector is calculated based on look-up tables, artificial intelligence, measured values, simulation, deterministic calculations.

[0087] Embodiment 6: Method according to one of the preceding embodiments, wherein the second predetermined region at least partially surrounds or adjoins the first solid layer.

[0088] Embodiment 7: Method according to one of the preceding embodiments, further comprising applying at least a second powder layer of the powder to the first solid layer, melting at least a first predetermined region of the applied second powder layer by means of the energy beam such that the first predetermined region of the applied second powder layer is converted into a second solid layer, wherein the desired position is adjacent to the second solid layer.

[0089] Embodiment 8: Method according to the preceding embodiment, wherein the second solid layer has a smaller extent than the first solid layer at least in a direction parallel to a surface facing the first solid layer.

[0090] Embodiment 9: Method according to one of embodiments 1 to 7, further comprising applying at least one second powder layer of the powder to the first solid layer and the solid layer region of the powder of the first powder layer, melting at least a first predetermined region of the applied second powder layer by means of the energy beam such that the first predetermined region of the applied second powder layer is converted into a second solid layer, melting a second predetermined region of the second solid powder layer and partially melting the second predetermined region of the powder of the first powder layer such thatthat the second predetermined region of the second powder layer is transferred into a fixed layer region of the second fixed layer corresponding to the desired contour and the second predetermined region of the first powder layer is transferred into the fixed layer region of the first fixed layer corresponding to the desired contour.,

[0091] Embodiment 10: Method according to one of the three preceding embodiments, wherein the second solid layer has a greater extent than the first solid layer at least in a direction parallel to a surface facing the first solid layer.

[0092] Embodiment 11: Method according to one of the four preceding embodiments, wherein the material is moved from the molten bath to the desired position and / or is transferred into the fixed layer region in such a way that it is transferred into a fixed desired shape.

[0093] Embodiment 12: Method according to the preceding embodiment, wherein the desired shape forms a transition, in particular a planar transition, between the first solid layer and the second solid layer.

[0094] Embodiment 13: Method according to one of the preceding embodiments, wherein a quantity of the molten material moved to the target position from the melt pool or a shape of the solid layer region of the first solid layer is adjusted by means of multiple melting by means of the energy beam, adjusting a scan length of the energy beam, adjusting the direction of movement of the energy beam, a speed, an acceleration, a focus position, a power of the energy beam and / or a distance between scan vectors of the energy beam.

[0095] Embodiment 14: Method according to the preceding embodiment, wherein the power of the energy beam, speed, acceleration and / or focus position of the energy beam are varied during the scan vector to adjust the amount of molten material moved from the melt pool to the desired position or the shape of the solid layer region of the first solid layer.Embodiment 15: Method according to one of the preceding embodiments, further comprising measuring an actual surface of the first solid layer, determining locations of the first solid layer with deviations from a desired shape, determining correction scan vectors for the locations of the first solid layer with deviations from a desired shape, melting the locations of the first solid layer with deviations from the desired shape by means of the energy beam and moving the energy beam according to the correction vectors such that melted material at the locations is moved to a desired correction position on or at the first solid layer.

[0096] Embodiment 16: Method according to the preceding embodiment, wherein the deviations comprise elevations and / or depressions.

[0097] Embodiment 17: Method according to one of the two preceding embodiments, wherein the actual surface is measured by means of a 3D scanner, optical coherence tomography, photogrammetry and / or digital image correlation.

[0098] Embodiment 18: Method according to any one of the preceding embodiments, further comprising measuring and / or estimating an effective depth, shape and / or dimension of the melt pool.

[0099] Embodiment 19: Method according to the preceding embodiment, wherein the effective depth, shape and / or dimension of the melt pool is measured by means of a 3D scanner, optical coherence tomography, photogrammetry and / or digital image correlation.

[0100] Embodiment 20: Method according to any one of the preceding embodiments, further comprising calibrating the energy beam before melting, wherein the results of the calibration are taken into account in the calculation of the scan vector.

[0101] Embodiment 21: Method according to one of the preceding embodiments, wherein the desired contour comprises an angle between parallel edges of two superimposed solid layers in a range of less than 45°, preferably less than 35°, and more preferably less than 25°. Embodiment 22: Method according to one of the preceding embodiments, wherein the at least one applied first powder layer has a height of 5 μm to 1 mm, preferably 30 μm to 0.8 mm, and more preferably 50 μm to 0.7 mm.

[0102] Embodiment 23: Method according to one of the preceding embodiments, wherein the powder has an average diameter d50 of 10 pm to 1 mm and preferably 30 pm to 200 pm.

[0103] Embodiment 24: Method according to one of the preceding embodiments, wherein a transport length from the actual position to the target position is in a range of 0.1 mm to 1.0 mm and preferably 0.2 mm to 1.0 mm.

[0104] Embodiment 25: Method according to one of the preceding embodiments, wherein one or more steps of the method are repeated, in particular repeated several times.

[0105] Embodiment 26: Method according to one of the preceding embodiments, wherein the energy beam is a laser beam and / or electron beam.

[0106] Embodiment 27: Method according to one of the preceding embodiments, wherein the method is computer-implemented.

[0107] Embodiment 28: Apparatus for producing a component by means of an additive manufacturing process using an energy beam, comprising: a process chamber with a build platform, an application device, in particular a squeegee, for applying a powder layer to the build platform, at least one energy beam source for emitting an energy beam onto the powder layer, a deflection unit for deflecting the energy beam, in particular a scanner having two mirrors and a focusing device consisting of optical lenses, or a deflection unit consisting of capacitor plates and a focusing device, wherein the apparatus is designed to carry out a method according to one of the preceding embodiments. Brief Description of the Figures

[0108] Further details and features will become apparent from the following description of exemplary embodiments, particularly in conjunction with the subclaims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are illustrated schematically in the figures. The same reference numerals in the individual figures designate identical or functionally identical elements, or elements that correspond to one another in terms of their functions.

[0109] In detail:

[0110] Figure 1 shows a device for producing a component by means of an additive manufacturing process;

[0111] Figures 2A to 2C show a schematic representation of an embodiment of the method according to the invention for producing a component by means of an additive manufacturing method;

[0112] Figure 3 is a plan view of a component produced by the method according to the invention;

[0113] Figures 4A and 4B show a side view of an exemplary layer structure with a constant and variable hatch distance;

[0114] Figures 5A and 5B show a side view of an exemplary layer structure with a constant and variable hatch distance;

[0115] Figures 6A and 6B show a plan view of another exemplary layer structure with a change in the melt pool size;

[0116] Figure 7 is a perspective view of a sublayer melting of overhangs

[0117] Figures 8A to 8C show exemplary steps of a surface correction; Figure 9 shows a schematic plan view with a variation of the scanning direction

[0118] Figure 10 a selective processing of extreme points

[0119] Figure 11 shows a possible step-by-step improvement of the surface; and

[0120] Figure 12 shows an example calibration surface.

[0121] Description of the embodiments

[0122] Figure 1 shows a device 100 for producing a component 102 using an additive manufacturing process. The device 100 comprises a process chamber 104 with a build platform 106. The build platform 106 is, in particular, height-adjustable. The device 100 further comprises an application device 108 for applying a powder layer 110a of a powder 110 to the build platform 106. The powder 110 has an average diameter d50 of 10 μm to 1 mm and preferably 30 μm to 200 μm. The application device 108 is, for example, a doctor blade. The device 100 further comprises at least one energy beam source 112 for emitting energy beams 114 onto the powder layer 110. The energy beam 114 is a laser beam and / or electron beam.The device 100 further comprises a deflection unit 115 for deflecting the energy beam 114, such as a scanner (not shown in detail), which has two mirrors and a focusing device consisting of optical lenses. Alternatively, the deflection unit 115 can consist of capacitor plates and a focusing device.

[0123] As will be explained in more detail below, the device 100 is designed to carry out a method for producing a component 102 by means of an additive manufacturing method using the energy beam 114.

[0124] Figures 2A to 2C show a schematic representation of an embodiment of the method according to the invention for producing a component 102 using an additive manufacturing process. First, a powder 110 is provided. At least a first powder layer 110a of the powder 110 is applied to the build platform 106 of the process chamber 104. Then, at least a first predetermined region 116a of the applied first powder layer 110 is melted by means of the energy beam 114 such that the first predetermined region 116a is converted into a first solid layer 118a. These steps can be repeated so that several solid layers 118 are built up one above the other. Several solid layers 118 are shown in Figures 2A to 2C purely as an example. Furthermore, a previously defined target contour 120 for the component 102 to be produced is indicated by a dashed line.The target contour 120 comprises several solid layers 118a, 118b of the component 102. In other words, not only the desired contour or shape for a single solid layer 118a, 118b is defined in advance, but also the desired contour of several solid layers 118a, 118b to be produced. This allows the outer shape of the respective solid layers 118a, 118b to be aligned or designed with smooth transitions.

[0125] As shown in Figure 2B, at least a second predetermined region 116b of the applied first powder layer 110a is melted by means of the energy beam 114 such that a melt pool 122 of the melted powder 110 is created. The second selected region 116b is a still unexposed region of the first powder layer 110 or a region that is subsequently applied with additional material of the powder 110 adjacent to the first solid layer 118a. Furthermore, at least one transport vector 123 of the energy beam 114 is calculated. The transport vector 123 is the vector that describes the desired transport direction of material from the melt pool 122. Based on the transport vector 123, a scan vector 124 for the energy beam 114 is then determined in order to realize the desired transport of material from the melt pool 122. The scan vector 124 includes at least one starting point and one end point for the movement of the energy beam 114.The scan vector 124 is calculated based on look-up tables, artificial intelligence, measured values, simulation, and / or deterministic calculations. The transport vector 123 can also be calculated based on look-up tables, artificial intelligence, measured values, simulation, and / or deterministic calculations.

[0126] The energy beam 114 is then moved according to the scan vector 124 such that molten material from the melt pool 122 is moved according to the calculated transport vector 123 from an actual position 125 to a target position 126 on or at the first solid layer 118a corresponding to the target contour 120. The target position 126 defines an area or location adjacent to the first solid layer 118a that is to be filled with material to form the target contour 120. A transport length from the actual position to the target position is in a range of 0.1 mm to 1.0 mm and preferably 0.2 mm to 1.0 mm. The scan vector 124 comprises at least one movement component of the energy beam 114 away from the target position 126. The molten material from the melt pool 122 is moved counter to the movement component.Through the interaction of the material and the energy beam 114, the molten material can be moved counter to the direction of movement of the energy beam 114. This phenomenon, or material transport, is specifically used in the method according to the invention to improve the resolution of the component 102 to be produced and, in particular, to achieve a resolution that corresponds at least to the layer thickness, but is preferably significantly more precise.

[0127] Furthermore, at least a second powder layer 110b of the powder 110 can be applied to the first solid layer 118a. Then, at least a first predetermined region 128a of the applied second powder layer 110 is melted by means of the energy beam 114 such that the first predetermined region 128a of the applied second powder layer 110 is converted into a second solid layer 118b. The target position 126 borders the second solid layer 118b. For example only, the target position 126 is shown in Figures 2B and 2C on the first solid layer 118a and adjacent to a second solid layer 118b. The molten powder 110 from the melt pool 122 is moved to the target position 126 in particular such that it is converted into a solid target shape. The desired shape forms a transition between the first solid layer 118a and the second solid layer 118b, as shown in Figure 2C.The transition is, in particular, a flat transition between the first solid layer 118a and the second solid layer 118b. This allows a smooth contour to be created and the steps between the respective layers 118 to be avoided and reduced. Thus, the desired contour 120 can comprise an angle α between parallel edges 127a, 127b of two superimposed solid layers 118a, 118b in a range of less than 45°, preferably less than 35°, and even more preferably less than 25°. The angle α between two adjacent solid layers 118a, 118b does not have to be identical, but can vary along the layer structure. The second solid layer 118b can have a smaller extension than the first solid layer 118a, at least in a direction parallel to a surface facing the first solid layer 118a.

[0128] The scan vector 124 can be varied relative to the calculated transport vector 123. In this way, the process parameters assigned to the scan vector 124 can be specifically varied over the length in order to specifically transport material with the melt pool 122. This can include the power, the focus position, the scanning speed, and indirect parameters such as the energy per unit length, melt pool depth, and the volume of the vapor pressure capillary or dent. The parameters can be varied over the length in discrete sections with a length of 0.01 mm to 10 mm, in particular 0.05 mm to 5 mm, in particular 0.2 mm to 2 mm. Alternatively, discretizations with fixed times can also be used, e.g., 0.001 ms to 10 ms, in particular 0.01 ms to 1 ms, in particular 0.02 ms to 0.2 ms. The accumulation behind the energy beam 114 caused by the material transport is varied depending on the movement length of the energy beam 114.For example, shorter energy beam paths produce a higher and shorter cluster than longer energy beam paths, where the cluster tends to have a flatter and longer shape.

[0129] As an alternative to discrete parameter changes, continuous changes are also possible in the form of ramps and spline definitions. In particular, the parameters are subdivided into parameters for material release, where the vapor pressure capillary expands, for bridging distances, where the vapor pressure capillary remains approximately constant, and for material uptake, where the vapor pressure capillary shrinks or is reduced to the point of disappearance.

[0130] Figure 3 shows a plan view of a component 102 produced using the method according to the invention. As shown in Figure 3, the second predetermined region 116b can at least partially surround the first solid layer 118a. The second predetermined region 116b thus forms a kind of shell around the already solid core region of the first layer 118a. Scan vectors 124 are also indicated in Figure 3 by way of example to indicate the movement of the energy beam 114 for forming the transition between the first solid layer 118a and the second solid layer 118b. An amount of molten material moved to the target position 126 from the melt pool 122 is adjusted by means of multiple melting, such as 1 to 1000 times, by means of the energy beam 114, adjusting a scan length of the energy beam 114, adjusting the direction of movement of the energy beam 114, a power of the energy beam 114 and / or a distance between scan vectors 124 of the energy beam 114.

[0131] The method according to the invention does not allow the construction of a stair-stepped component according to the prior art to be carried out, but rather, particularly in areas with a shallow angle, uses appropriate parameters / scanning directions and multiple scanning to create a material transport that approximates the resulting component contour to the actually desired contour. This allows an oversized contour to be created initially and the material to be guided to the correct position through the effect of the material transport. In this example, the energy beam would start in the area to be filled and move outwards to transfer material from the excess material to the desired position. The method thus allows an improvement in resolution during additive manufacturing in a powder bed, so that the achieved accuracy corresponds at least to the layer thickness, but is preferably more precise.

[0132] Depending on the gradient of the geometry, i.e. the inclination of the surface, locally different thicknesses of the additional material (shell) can be converted from the powdery to the solid state by melting and then processed or transported in order to achieve the desired inclination at that location. An example of this can be seen in Figure 3. There is a core region in the form of the first solid layer 118a, which is not processed by the additional exposure and basically represents the layer 118a as is the case in the prior art, i.e. a cross-sectional area with the height of the layer thickness. For this reason, the second selected region 116b is created as a shell of additional material, the processing of which creates the desired contour. The scan vectors 124 shown in Figure 3 show how the energy beam 114 can move to build up material towards the core.The size of the required envelope in Figure 3 can be expanded to the size of the underlying layer. This provides material for material transport to the layer above. For this to be possible, however, the layer 118b above must be smaller than the layer 118a below it. A smaller layer 118b means that the projection of layer 118b does not cover the underlying layer 118a. If the upper layer 118b does not cover the lower layer 118a, the described steps arise, which are to be smoothed by the material transport.

[0133] Precisely such targeted material transport is used to produce surfaces 130 without overhangs, even in the core area. Through repeated and targeted exposure, the surface 130 can be smoothed and previously formed overhangs removed. A uniform surface 130 prevents subsequent process errors, particularly those caused by faulty powder application. This includes, in particular, the collision of the doctor blade with the overhang.

[0134] The above embodiments of the method according to the invention are particularly suitable for sections in which the component 102 tapers, i.e., at least in sections, the contour of the subsequent layer 118b is smaller than the preceding layer 118a, i.e., for component sections in which the projection of the upper layer 118b completely covers the underlying layer 118a. However, a component 102 can alternatively or additionally widen, for example, locally, partially, or completely, which means that the upper layer 118b not only covers the underlying layer 118a, but its projection exceeds the contour of the underlying layer 118a, and thus parts of the contour of the upper layer 118b are found above unmelted powder 110.

[0135] Figure 4A shows a side view of an exemplary layer structure with a constant hatch distance. Figure 4B shows a side view of an exemplary layer structure with a variable hatch distance. Figures 4A and 4B show a first or lower solid layer 118a and, above it, a second unmelted powder layer 110b. Also shown is the melt pool 122 created by the energy beam 114, as well as the hatch distance 132, i.e., the distance between two adjacent energy beam paths. As can be seen in particular from Figure 4B, by varying the energy beam parameters, the energy input in particular can be varied, which leads to a variable size of the melt pool. The hatch distance 132 can also be varied by varying the scan vectors 124 and scan distances.

[0136] In the case of an expanding component 102, no material transport can be used as before to create the contour with sublayer resolution. However, as in the case of tapering, the energy beam 114 can vary during the expansion. This means that sublayers can also be created by deliberately varying the scan vectors 124, multiple exposures, different / adaptive energy input, adjusting the scan length of the energy beam 114, adjusting the direction of movement of the energy beam 114, a speed, an acceleration, a focus position, and a power of the energy beam 114. In this way, the second predetermined region 116b can be transferred into a fixed layer region 133a of the first fixed layer 118a corresponding to the target contour 120.

[0137] As can be seen in Figure 4A, the energy beam 114 creates a melt pool 122, the depth of which depends on several factors, such as energy input or the temperature of the powder 110 and thus the previous melt pool 122. Such a melt pool 122 has the same size in conventional additive manufacturing processes due to their non-adaptive systems. However, the melt pool 122 influences not only the powder layer 110 to be melted, but also the underlying layers 118.

[0138] Investigations using micrographs show that typically up to six previous layers 118 are locally remelted when remelting the current powder layer 110. The depth can also be influenced by statistical process fluctuations.

[0139] This is to be used as a further option to obtain sublayer resolution by adjusting the scanning strategy and the energy input of the energy beam 114. As can be seen schematically in Figure 4B, the distance between the energy beam paths, ie the hatch distance 132, can be reduced and the introduced energy can be varied in order to obtain a targeted influence of the melt pool 122 on the underlying layer.

[0140] Figure 5A shows a side view of an exemplary layer structure with a variable hatch distance 132 and variable melt pool size. In addition, the lower part of Figure 5A shows a power P of the energy beam 114 plotted against the direction of movement x of the energy beam 114. Figure 5B shows a side view of an exemplary layer structure with a variable hatch distance 132 and variable melt pool size. In addition, the lower part of Figure 5B shows a power P and the speed v of the energy beam 114 plotted against the direction of movement x of the energy beam 114 for different layers 110a, 110b. Thus, at least a second powder layer 110b of the powder 110 can be applied to the first solid layer 118a and solid layer region 133a of the first solid layer 118a.Then, at least a first predetermined region 128a of the applied second powder layer 110 is melted by means of the energy beam 114 such that the first predetermined region 128a of the applied second powder layer 110b is converted into a second solid layer 118b. Furthermore, a second predetermined region 128b of the second solid powder layer 110b is converted into a solid layer region 133b of the second solid layer 118b corresponding to the target contour 120, and the second predetermined region 116b of the first powder layer 110a is converted into the solid layer region 133a of the first solid layer 118a corresponding to the target contour 120. In other words, the process parameters of the energy beam in the edge regions of the component 102 to be produced can be varied such that it penetrates from a second powder layer 110b into an underlying powder layer 110a.Thus, as shown in Figure 5A, the power P of the energy beam 114 may be constant in the first predetermined region 128a and then gradually reduced in the second predetermined region 128 to gradually reduce the penetration depth. As shown in Figure 5B, in the first powder layer 110a, the power P of the energy beam 114 may be constant in the first predetermined region 116a and then, after a sudden increase upon entering the second predetermined region 116b, gradually reduced to gradually reduce the penetration depth. Additionally, the speed of the energy beam 114 may be constant in the first predetermined region 116a and then, after a sudden decrease upon entering the second predetermined region 116b, gradually increased to gradually reduce the penetration depth.As further shown in Figure 5B, in the second powder layer 110b, the power P of the energy beam 114 may be constant in the first predetermined region 128a and then, after a sudden increase upon entering the second predetermined region 128b, gradually decreased to gradually reduce the penetration depth. Additionally, the speed of the energy beam 114 may be constant in the first predetermined region 128a and then, after a sudden decrease upon entering the second predetermined region 128b, gradually increased to gradually reduce the penetration depth.

[0141] In the case of an overhang, steps equal to the powder layer thickness are created on the underside of the component 102, as shown in Figure 5A. Depending on how the software has defined the manufacturing process, the steps are outside the target contour 120 or smaller, with unmelted powder 110 being found within the target contour 120. With the help of the variable melt pool 122, the area of ​​unmelted powder 110 can be specifically melted when processing the overlying layer, creating a sublayer resolution that corresponds to the target contour 120 or at least closely approximates it. This means that the component 102 requires significantly less or no post-processing, and the resulting improved surface also increases the component strength.

[0142] Using typical manufacturing parameters, a powder layer is melted and bonded to the layer below. This can only happen because the melt pool 122 extends into the layer below, thus melting this layer as well and thus creating a good weld. This can also be seen in Figures 5A and 5B. Here, the melt pools 122 extend from the second layer 110b, 118b into the first layer 110, 118a to create a proper connection between the layers 118a, 118b. The melt pool 122 is deeper than one layer thickness to enable good welding of the two layers 118a, 118b. However, this is not necessary in the downskin areas, since in the edge zones of layer 118b there is no material below layer 118a. At this point there is only powder which is not to be melted and therefore a melt pool 122 must be created which does not reach into the underlying layer 118a.The melt pool can be adjusted so that it does not extend into the next layer. By adjusting the parameters, the melt pool can be made smaller or wider. This helps to melt the HO powder near the contour in a targeted manner, so that the melt pools run along the contour. Parameters such as laser speed, laser power, and focus can be adjusted to vary the melt pool size.

[0143] As can be seen in Figures 5A and 5B, the energy input is adjusted via the energy beam power P and energy beam velocity v close to the target contour 120. It can also be seen that the exposure in the second layer 118b continues to expose the smallest areas of layer 118a. This helps to enable even more precise melting of the contour. As long as layer 118b lies above layer 118a, the contour in layer 118a can also be produced more precisely by finely adjusting the melt pool 122.

[0144] Figure 6A shows a top view of another exemplary layer structure with a change in the melt pool size. Figure 6B shows a top view of another exemplary layer structure with a change in the melt pool size. The change in the melt pools must be taken into account in the process strategy; this is illustrated in Figures 6A and 6B. Here, it is shown that near the edge region and with increasing position in a direction x perpendicular to edges 127a, 127b of the solid layers 118a, 118b, the melt pool becomes smaller. This leads to hatch distances having to be adjusted, and additional energy beam paths being added due to narrower melt pools.Figure 6A shows a variant in which the process parameters of the energy beam 114 are varied with increasing position in the direction x perpendicular to edges 127a, 127b of the solid layers 118a, 118b for each path of the energy beam 114 in order to produce a melt pool 122 that decreases in the direction x. Figure 6B shows a variant in which the energy beam 114 is moved in a direction y tangentially or parallel to edges 127a, 127b of the solid layers 118a, 118b and the process parameters of the energy beam 114 are varied with increasing position in the direction x perpendicular to edges 127a, 127b of the solid layers 118a, 118b for each path of the energy beam 114 in order to produce a melt pool 122 that decreases in the direction x.

[0145] A wide variety of options can be used to achieve the desired melt pool geometry. Firstly, a data set can be created that the preparation software accesses and uses to adjust the energy beam paths during path planning and generate the appropriate melt pool 122. This can be done using fixed algorithms or by using AI-based build strategies.

[0146] Furthermore, there is the possibility of melt pool monitoring in the process, which means that the size of the melt pool 122 is measured or estimated by a monitoring system (e.g. camera-based) outside the energy beam path or in the course of the energy beam path, and a change to the parameters can then be made using a control system or AI.

[0147] Figure 7 shows a perspective view of sublayer melting of overhangs using variable scan vectors 124, scan spacing, and energy inputs. Shown is a section 134 to be filled between a first solid layer 118a and a second solid layer 118b, which projects beyond the first solid layer 118a. However, these overhang sublayers do not have to be created in individual fixed exposures. As in the other suboptions, the directions, spacing, and lengths of the scan vectors 124 can vary in order to more specifically obtain a defined melt pool 122 in the underlying powder layer 110a, while also avoiding damaging the top layer or causing unwanted material transport. The goal is to introduce enough energy into the lower, non-melted layer without influencing / changing the upper layer, in order to melt the powder 110 and fuse it with the other layers.

[0148] The method may further comprise measuring an actual surface of the first solid layer 118a. The actual surface may be measured using a 3D scanner, optical coherence tomography, photogrammetry, and / or digital image correlation. The measurement may determine locations of the first solid layer 118a with deviations 136 from a desired shape. Furthermore, the method may comprise determining correction scan vectors 138 for the locations of the first solid layer 118a with deviations 136 from a desired shape. Then, the locations of the first solid layer 118a with deviations 136 from the desired shape may be melted using the energy beam 114 and moving the energy beam 114 according to the correction scan vectors 138 such that melted material at the locations is moved to a desired correction position 140 on or at the first solid layer 118a.

[0149] For example, due to changing powder properties, variations in the powder layer 110, tolerances in the drives, difficulty predicting material flow, etc., deviations between the planned and achieved surface may occur. To achieve a specific surface, after exposure to any scan pattern, the resulting surface can be subsequently recorded with sensors in order to re-expose it to modify the surface.

[0150] During exposure or scanning or in a subsequent step, the resulting surface 130 can be measured. For this purpose, 3D scanners based on structured light projectors, optical coherence tomography, photogrammetry systems, digital image correlation, and others can be used. As Figure 1 shows by way of example, the surface 130 can be measured / observed / inspected. An optical system determines whether depressions or elevations are forming in order to subsequently make adjustments in the process or to detect locations for post-processing. For example, a first camera 142a can be provided for optical detection. However, this does not require a system external to the energy beam 114. Alternatively or additionally, measurement of the print bed using a system in the energy beam path is possible.For this purpose, a beam splitter 144 can be integrated into the beam path, which redirects reflected energy beam light to a second camera 142b. The energy beam 114 is emitted by the energy beam source 112, penetrates the beam splitter 144, and is redirected by the deflection unit 115 to the powder layer 110. The light reflected by the powder layer 110 is in turn redirected by the deflection unit 115 toward the energy beam source 112. The beam splitter 144 is arranged in the beam path and redirects the reflected energy beam light to the second camera 142b.

[0151] Figures 8A to 8C show exemplary steps for correcting surface 130. Figure 8A, for example, shows a raised portion 146 and a depression 148 in surface 130. Furthermore, a scan vector 124 for energy beam 114 is shown. Based on the actual geometry determined by the measurement, the deviation from the target geometry can now be determined and checked for tolerances. Path planning is performed, for example, by planning and executing a scan vector 124 between local or global raised portions 146 and depressions 148.

[0152] Figure 8B shows the material transport from the raised portion 146 to the recess 148 opposite to the orientation of the scan vector 124. Thus, during calculation / path planning, it must be taken into account that the material transport occurs opposite to the scanning direction and is always directed backward due to the melt pool dynamics, particularly the throw distance, flow velocity, and keyhole size. In other words, the scan vector 124 must move from the recess 148 to the raised portion 146.

[0153] Figure 8C shows the state of the surface 130 after exposure by the energy beam 114 and the material transport from the elevation 146 to the depression 148. The result is a smooth surface 130.

[0154] Depending on the material transport rates stored or determined from the measurement data, several different scan vectors 124, possibly overlapping vectors, or even the number of scan vectors 124 to be executed multiple times can be determined, whereby the adaptation of the surface to the desired geometry can be achieved with a lower risk of creating new elevations and depressions.

[0155] The scan vector 124 can be varied relative to the calculated scan vector 124. For example, when transporting from a maximum or elevation 146 to a minimum or depression 148, it may be advantageous to slightly vary the start and stop positions laterally and along the direction to avoid the formation of excessively localized material transport and to achieve uniform transport.

[0156] A variation of the scan vectors 124 and thus of the material transport is shown as an example in Figures 9 and 10. Figure 9 shows a schematic top view with a variation of the scan direction to prevent material transport from being too spotty, as well as multiple exposure and variation of the start and stop points. The multiple exposure is shown by several similarly oriented scan vectors 124. Figure 10 shows spot processing of extreme points, such as a superelevation 146, and optimized material transport by changing the scan vector 124 (direction, energy input). The multiple exposure, varying scan directions, and the changed energy input enable uniform material transport. The scan directions can be random, as shown on the right side of Figure 10, or, as shown on the left side of Figure 10, have an angle to the previous exposure with each new exposure sequence.The result is a flattened cant of 150 or smoothing if executed accordingly.

[0157] As Figure 10 exemplifies, any desired elevations and depressions can be machined. In particular, through targeted variation of the scan vector 124 and its energy input, such as speed, energy beam power, focus, distance, etc., the material is optimally shifted and the formation of new extreme points can be avoided. The right-hand part of Figure 10 shows the changing energy input over the course of the scan vector 124. The upper diagram shows the energy beam power 152 as a function of the path or scan profile 154 for a standard scan profile 156 and the adaptive scan profile 158. The lower diagram shows the scan speed 160 as a function of the path or scan profile 154 for a standard scan profile 156 and the adaptive scan profile 158.

[0158] For this purpose, the volume or height change of the melt track taken into account during the absorption phase (deceleration of the energy beam 114, reduction of the energy beam 114) or the release phase (acceleration, enlargement of the keyhole) relative to an ideal plane can be added or subtracted. The calculation required for adaptive path planning can be performed using look-up tables, artificial intelligence, based on measured values, 3D scanners (adaptive), based on simulations, and deterministic calculations.

[0159] Since even targeted smoothing can result in a new texture due to the scan direction used, final smoothing can be carried out by exposing again at a large angle or perpendicular to the previous scan direction. However, the keyhole formation should be kept to a minimum by reducing the applied energy, i.e. reduced beam power and / or shortening the exposure time, i.e. higher energy beam speed. This final smoothing can be carried out by multiple scans, depending on the desired and required surface. With multiple scans, the angle, scan speed and power should preferably be varied and adjusted between each scan process. This means that an adaptive scan speed must be possible and must be taken into account when planning the path. The energy beam speed and energy beam strength can vary along a scan vector 124.Such a multiple scan can also be performed by "wobbling" the energy beam 114 over the area to be processed, i.e., the energy beam 114 oscillates back and forth. By wobbling, an area can be processed in a targeted manner, but the dynamics of the scanner must be taken into account. Due to acceleration processes, the scanner does not have a constant speed. Through multiple exposure, the surface is gradually improved until the desired surface quality is achieved.

[0160] Figure 11 shows such a possible step-by-step improvement of the surface 130 and reduction of elevations 146 or depressions 148. Image section A shows the state of the surface 130 after a first exposure with clear elevations 146. Image section B shows the state of the surface 130 after improvement through repeated exposure. Image section C shows possible surfaces 130 after multiple exposures, for example, smooth as shown in the lower image section or with a defined surface texture as shown in the upper image section.

[0161] A self-learning algorithm can optimize the entire process of targeted material transport. This can intervene in the initial path planning or in the adaptive system during the process. In the first case, a self-learning algorithm can optimize the initial path planning by determining the optimal process combination suitable for the geometry, powder, and machine from a database of process parameters. The more precise and comprehensive the database, the more accurately the algorithm can predict where material will build up and to what extent post-exposure is necessary. In the second case, artificial intelligence accesses multiple data sources: on the one hand, a database of empirical values, with process parameters and results; on the other, the artificial intelligence directly observes the process.This allows the artificial intelligence to react to problems that may arise during the process and adjusts the exposure to achieve the desired result in each layer. Monitoring the process and using artificial intelligence allows for consideration of powder dynamics, particularly powder entry into the melting track, the ejection of powder 110, etc., as well as thermal expansion and tolerances. However, for artificial intelligence to intervene in the process, process monitoring is required, as already described in connection with the adaptive or sensor-based system and surface measurement.

[0162] To ensure optimal material transport, a calibration process is preferably used. Calibration can be combined with all of the process variations presented here. This allows the properties of the powder, machine, and environment to be determined. The collected information can be used to predict an optimized path plan during the initial path planning, allowing material transport to be used in a targeted manner. The additional information from the calibration process is also beneficial in the case of an adaptive system, artificial intelligence, or subsequent smoothing.

[0163] Such a calibration process can be performed by printing a small number of layers onto a flat plate. During the calibration process, areas are exposed using different exposure strategies, speeds, and other parameter changes. The calibration process is monitored and / or the finished object is assessed, for example, automatically or subsequently through measurements on additional devices, in order to calculate optimal path planning for the subsequent production of the actual component 102. The calibration process thus enables data to be recorded and characteristic values ​​to be determined, which subsequently affect process parameters such as energy beam power, acceleration, speed, focus position, or number of overexposures, angles, or offset values.

[0164] Figure 12 shows an example calibration surface 162. The calibration surface 162 is used to determine various parameter combinations for creating different surfaces or targeted material transport. For example, Figure 11 shows how the surface is divided into different regions. In the example shown, the calibration surface 162 comprises four surface regions 164a, 164b, 164c, 164d. Each region 164a, 164b, 164c, 164d is exposed differently in order to determine parameter combinations that either lead to smooth surfaces, as in the second region 164b, or enable targeted material transport, for example to create elevations 146, as in the fourth region 164d. The information obtained from this is then incorporated into the optimized production of the actual component 102.However, in order to create such a targeted melt pool 122, calibration, as explained in more detail below, measurement of the melt pool 122, and / or simulation should be performed, which facilitates path planning. Such calibration and parameter study should preferably be performed for each system and each powder 110 to obtain optimal results, since each system and powder 110 can behave differently.

[0165] List of reference symbols

[0166] Device Component Process chamber Build platform Application device Powder a, 110b Powder layers Energy beam source Energy beam Deflection unit a, 116b, 116c Predetermined areas of the first powder layer a, 118b Fixed layers Target contour Melt pool Transport vector Scan vector Actual position Target position a, 127b Edge a, 128b Predetermined areas of the second powder layer Surface Hatch distance a, 133b Fixed layer area Section to be filled Deviation Correction scan vector Correction target position a, 142b Cameras Beam splitter Superelevation Depression Flattened superelevation Energy beam power Path or scan path Standard scan path Adaptive scan path

[0167] Scan speed

[0168] Calibration surfacea, 164b 164c, 164d Whether surface preparation beforehand

Claims

Claims 1. A method for producing a component (102) by means of an additive manufacturing process using an energy beam (114), comprising the steps: (a) Providing a powder, (b) applying at least a first powder layer (110a) of the powder to a build platform (106) of a process chamber (104), (c) defining a target contour (120) of the component (102), wherein the target contour comprises a plurality of solid layers of the component (102), (d) melting at least a first predetermined region (116a) of the applied first powder layer (110a) by means of an energy beam (114) such that the first predetermined region (116a) is converted into a first solid layer (118a), (e) melting at least a second predetermined region (116b) of the applied first powder layer (110a) by means of the energy beam (114) such that a melt pool (122) of the melted powder is formed, (f) calculating at least one transport vector (123) of the energy beam (114) as a function of the desired contour (120) of the component (102), and (g) moving the energy beam (114) according to a scan vector (124) such that molten material from the melt pool is moved according to the calculated transport vector (123) from an actual position (125) to a desired position (126) on or at the first fixed layer (118a) corresponding to the desired contour (120) and / or the second predetermined region (116b) is transferred into a fixed layer region (133a) of the first fixed layer (118a) corresponding to the desired contour (120).

2. Method according to the preceding claim, wherein the scan vector (124) comprises at least one movement component of the energy beam (114) away from the desired position (126), wherein the molten material from the melt pool (122) is moved counter to the movement component.

3. Method according to one of the preceding claims, wherein the scan vector (124) comprises at least one start point and one end point for the movement of the energy beam (114).

4. Method according to one of the preceding claims, wherein the scan vector (124) is varied relative to the calculated transport vector (123).

5. The method according to any one of the preceding claims, wherein the second predetermined region (116b) at least partially surrounds or adjoins the first solid layer (118a).

6. Method according to one of the preceding claims, further comprising applying at least a second powder layer (110b) of the powder (110) to the first solid layer (118a), melting at least a first predetermined region (128a) of the applied second powder layer (110b) by means of the energy beam such that the first predetermined region (128a) of the applied second powder layer is converted into a second solid layer (118b), wherein the desired position (126) adjoins the second solid layer (118b), wherein the second solid layer (118b) has a smaller extent than the first solid layer (118a), in particular at least in a direction which is parallel to a surface facing the first solid layer (118a).

7. The method according to one of claims 1 to 6, further comprising applying at least a second powder layer (110b) of the powder (110) to the first solid layer (118a) and the solid layer region (133a), melting at least a first predetermined region of the applied second powder layer (110b) by means of the energy beam (114) such that the first predetermined region (128a) of the applied second powder layer (110b) is converted into a second solid layer (118b), melting a second predetermined region (128b) of the second powder layer (110b) and partially melting the second predetermined region (116b) of the powder (110) of the first powder layer (110a) such thatthat the second predetermined region (128b) of the second powder layer (110b) is transferred into a fixed layer region (133b) of the second fixed layer (118b) corresponding to the desired contour (120) and the second predetermined region (116b) of the first powder layer (110a) is transferred into the fixed layer region (133a) of the first fixed layer (118a) corresponding to the desired contour (120), wherein the second fixed layer (118b) is in particular at least in a direction which is parallel to one of the first fixed layers (118a), facing surface has a greater extension than the first solid layer (118a).

8. Method according to one of the two preceding claims, wherein the material is moved from the molten bath (122) to the desired position (126) and / or is transferred into the fixed layer region (133a) in such a way that it is transferred into a fixed desired shape.

9. Method according to the preceding claim, wherein the desired shape forms a transition, in particular a planar transition, between the first solid layer (118a) and the second solid layer (118b).

10. The method according to one of the preceding claims, wherein a quantity of the molten material moved to the target position (126) from the melt pool (122) or a shape of the solid layer region (133a) of the first solid layer (118a) is adjusted by means of multiple melting, in particular 1 to 100 times, by means of the energy beam (114), adjusting a scan length of the energy beam (114), adjusting the direction of movement of the energy beam (114), a speed, an acceleration, a focus position, a power of the energy beam (114) and / or a distance between scan vectors (124) of the energy beam (114), wherein for adjusting the quantity of the molten material moved to the target position (126) from the melt pool (122) or the shape of the solid layer region (133a) of the first solid layer (118a), in particular the power of the energy beam (114), speed,Acceleration and / or focus position of the energy beam can be varied during the scan vector (114)., 11. The method according to any one of the preceding claims, further comprising measuring an actual surface of the first solid layer (118a), determining locations of the first solid layer (118a) with deviations from a desired shape, determining correction scan vectors for the locations of the first solid layer (128) with deviations from a desired shape, melting the locations of the first solid layer (118a) with deviations from the desired shape by means of the energy beam (114) and moving the energy beam according to the correction vectors such that melted material at the locations is moved to a desired correction position on or at the first solid layer (118a).

12. Method according to the preceding claim, wherein the actual surface is measured by means of a 3D scanner, optical coherence tomography, photogrammetry and / or digital image correlation.

13. Method according to one of the preceding claims, further comprising measuring and / or estimating an effective depth, shape and / or dimension of the melt pool, wherein the effective depth, shape and / or dimension of the melt pool is measured in particular by means of a 3D scanner, optical coherence tomography, photogrammetry and / or digital image correlation.

14. Method according to one of the preceding claims, further comprising calibrating the energy beam before melting, wherein the results of the calibration are taken into account in the calculation of the scan vector, and / or wherein the desired contour (120) comprises an angle (a) between parallel edges (127a, 127b) of two superimposed solid layers (118a, 118b) in a range of less than 45°, preferably less than 35° and more preferably less than 25°.

15. Device for producing a component by means of an additive manufacturing process using an energy beam, comprising: a process chamber (104) with a build platform (106), an application device (108), in particular a squeegee, for applying a powder layer (110a, 110b) of a powder (110) to the build platform (106), at least one energy beam source (112) for emitting an energy beam (114) onto the powder layer (110a, 110b), a deflection unit (115) for deflecting the energy beam, in particular a scanner which has two mirrors and a focusing device consisting of optical lenses, or a deflection unit (115) consisting of capacitor plates and a focusing device, wherein the device is designed to carry out a method according to one of the preceding claims.

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