Method and apparatus for additive manufacturing of a workpiece

Abstract

A method and apparatus for additive manufacturing of a workpiece (14a, 14b, 14c) having a lateral workpiece dimension (36) using a first data set (50) defining the workpiece in a plurality of workpiece layers (18) arranged one above the other. A manufacturing area (40) is selected on a production platform (12) having a lateral platform dimension (38) greater than the lateral workpiece dimension (36) on which the workpiece (14) should be manufactured layer by layer. A plurality of defined material layers (16) is produced using the first data set (50). Advantageously a second data set (54) is used representing a warping of the respective material layer (16) in relation to the manufacturing area (40). The individual material layers (16) are produced using the first data set (50) and using the second data set (54).

Description

[0001] This invention relates to a method for additive manufacturing of workpieces, the method comprising the following steps:

[0002] a) Obtain a first dataset that defines the workpieces in multiple workpiece layers arranged vertically above and below each other;

[0003] b) Select a manufacturing area on a production platform with a lateral platform size larger than the lateral workpiece size, wherein the manufacturing area defines the section of the production platform on which workpieces should be manufactured layer by layer.

[0004] c) Using the first dataset to produce a defined material layer in a manufacturing area on a production platform, wherein the material layer is used to produce a defined workpiece layer formed by multiple workpiece layers arranged vertically to each other; and

[0005] d) Repeat step c), wherein additional defined workpiece layers are produced from multiple workpiece layers arranged one above the other.

[0006] The present invention also relates to an apparatus for additive manufacturing of a workpiece having a lateral workpiece dimension, the apparatus comprising: a production platform having a lateral platform dimension larger than the lateral workpiece dimension; a structured tool movable relative to the production platform; a first memory configured to acquire a first dataset defining a workpiece in a plurality of workpiece layers arranged vertically above each other; and a control unit configured to use the first dataset to move the structured tool relative to the production platform, thereby producing a plurality of material layers layer by layer in a manufacturing area on the production platform, wherein each of the plurality of material layers is used to produce a defined workpiece layer formed by the plurality of workpiece layers arranged vertically above each other.

[0007] In some cases, additive manufacturing methods used to manufacture workpieces are referred to as 3D printing. Various additive manufacturing methods exist. In so-called selective laser sintering (SLS) or selective laser melting (SLM), a powder bed with a large number of planarly distributed powder particles is used. These are typically metal powder particles. However, they can also be plastic particles or polymers, such as those formed from polyamide (PA) or polymethyl methacrylate (PMMA). The powder particles selected in the powder bed are melted and / or fused together by means of one or more laser or electron beams and thus bonded together. In so-called binder jetting, powdered raw materials are bonded together with a liquid binder at selected locations. Thus, in each case, desired workpiece layers can be selectively manufactured in the powder bed. After manufacturing such workpiece layers, new powder layers are distributed on the powder bed, and other workpiece layers can be selectively manufactured. Therefore, overall, the workpiece is constructed layer by layer from workpiece layers arranged one above the other. In other additive manufacturing methods, workpiece material can be selectively applied to a production platform to manufacture the workpiece layer by layer. The workpiece material can be, for example, molten plastic.

[0008] Typically, the lateral dimension of the production platform is larger than that of the workpiece to be manufactured, so that the production platform can support the workpiece without overhang during manufacturing. Correspondingly, when the manufacturing process is started, a unique manufacturing area on the production platform must be selected, at least implicitly, for each workpiece.

[0009] US 10,220,566 B2 discloses a method and apparatus of the type described at the outset, and proposes measuring the selected material layer during processing so as to make adjustments as necessary during the manufacture of subsequent workpiece layers. In this way, manufacturing defects can be identified early and corrected during processing. That is, it has been demonstrated that fluctuations in various processing parameters make it difficult to manufacture workpieces with high requirements for dimensional accuracy, reproducibility, and load-bearing capacity.

[0010] WO 2019 / 206903 A1 discloses another method for additive manufacturing of workpieces and a corresponding apparatus, wherein dimensional and / or geometric properties of workpiece layers are measured during processing, thereby improving the accuracy and reproducibility of the manufacturing process.

[0011] WO 2018 / 064349 A1 discloses a method for additive manufacturing of workpieces, in which so-called model markers are added to the CAD data of the workpiece. As the workpiece is manufactured, physical markers are created. The deviation between the position of the model markers in the CAD data and the position of the physical markers in the 3D scanner image is determined to produce a corrected print command.

[0012] WO 2018 / 234331 A1 discloses a method and apparatus for additive manufacturing of workpieces, wherein the measurement results of the workpiece are compared with the results of simulated measurements.

[0013] WO 2020 / 094732 A1 discloses a method and apparatus for inspecting the surface of a powder bed in order to obtain the most uniform workpiece layer possible and avoid cracks, pores, dents, etc. during the additive manufacturing process of the workpiece.

[0014] From the publication Wegner A, Witt G (2013), "Ursachen für mangelnde Reproduzierbarkeit beim Laser-Sintern von Kunststoffbauteilen," RTejournal-Forum für Rapid Technologie, Vol. 2013, available at https: / / www.rtejournal.de / ausgabe10 / 3818, it is known that non-uniform temperature control during the manufacturing process of laser-sintered plastic components can be a cause of insufficient reproducibility and dimensional accuracy. A novel temperature control system is proposed here, which aims to achieve more uniform temperature and cooling conditions.

[0015] In this context, the object of the present invention is to provide a method and apparatus of the type described at the outset, which can improve the dimensional accuracy and reproducibility of additively manufactured workpieces in a cost-effective manner.

[0016] According to a first aspect of the invention, this objective is achieved by a method of the type described at the beginning, wherein a second dataset is obtained prior to step c), the second dataset representing the warpage of the defined material layer in relation to the manufacturing region, and wherein the defined material layer is produced using both the first dataset and the second dataset.

[0017] According to another aspect of the invention, this objective is achieved by a device of the type described at the outset, the device having a second memory configured to acquire a second dataset, wherein the second dataset represents warpage of a defined workpiece layer in relation to a manufacturing area, and wherein a control unit is configured to move a structured tool relative to a production platform using both the first dataset and the second dataset.

[0018] Particularly advantageously, by means of a computer program with program code, the method described above can be implemented, and the program code can be run on the control unit of the device of the type described.

[0019] The novel method and apparatus are based on the understanding that unique manufacturing regions of a workpiece on a production platform can cause unique warping in the additively manufactured material layer, which is related to the manufacturing region. This unique warping, when compared with a target dimension of the workpiece layer derived from a first dataset, results in dimensional and / or geometric deviations in the manufactured workpiece layer. Therefore, the dimensional accuracy of the additively manufactured workpiece may be related to a correspondingly selected unique manufacturing region on the production platform. The novel method and apparatus use a second dataset representing the position-related warping of the additively manufactured workpiece layer in terms of production volume on the production platform, particularly representing position-related dimensional and / or geometric deviations relative to a corresponding target dimension. In some embodiments, the second dataset may represent the position-related warping of the additively manufactured material layer in three spatial directions, each orthogonal to the other. Advantageously, the three orthogonal spatial directions may include two orthogonal spatial directions parallel to the production platform and a third spatial direction perpendicular to the production platform. Thus, in some preferred embodiments, the second dataset may represent the position-related warping of the additively manufactured material layer relative to multiple spatial volumes (voxels) in the production volume on or above the production platform.

[0020] The unique warpage associated with a corresponding manufacturing area can have various causes. This includes non-uniform temperature distribution and / or temperature profiles within the production volume. For example, lateral walls on the production platform that define the powder bed can affect the temporal and spatial temperature profiles within the production volume, resulting in higher or lower processing temperatures, faster or slower heating, and / or faster or slower cooling depending on the distance of the manufacturing area from the lateral walls. The number and lateral spacing of multiple workpieces manufactured simultaneously on the production platform can also affect the temporal and spatial temperature distribution. Furthermore, the accuracy with which the structuring tool can move relative to the production platform can vary depending on the corresponding manufacturing area on the production platform. The novel method and corresponding equipment allow such location-dependent processing variations to be accounted for early in the manufacturing process and necessary processing corrections to be performed when necessary. When necessary, in addition to other measures to improve the reproducibility and dimensional accuracy of additively manufactured workpieces, corrections can be performed, for example, by early inspection of the powder bed before structuring the workpiece layers accordingly. In some embodiments, a second dataset can be provided and obtained without large-scale modifications to the hardware of the equipment already in use. Therefore, in some cases, this novel method can be implemented cost-effectively on existing equipment, especially with the aid of the aforementioned computer program. Correspondingly, the novel method and corresponding equipment facilitate cost-effective improvement in the dimensional accuracy and reproducibility of additively manufactured workpieces. The aforementioned objectives are fully achieved.

[0021] In a preferred embodiment of the invention, a defined material layer is produced by means of a structured tool, and the structured tool is moved relative to the production platform using a first dataset and a second dataset.

[0022] In this design, a second dataset is used to modify the process for manufacturing defined material layers (as initially obtained using the first dataset) to counteract the location-dependent, unique warpage of the defined material layers. This modification is integrated to some extent into the conventional machining process. Depending on the selected manufacturing area, the structured tool moves relative to the production platform with motion parameters that differ from those without the second dataset. The structured tool can be, for example, a laser beam, electron beam, melting head, hot air nozzle, or other tools that can selectively manufacture workpiece layers on the production platform. Other or modified motion parameters may include faster or slower movement of the structured tool relative to the production platform, modified trajectories, and / or modified processing temperatures. This design allows for cost-effective implementation of the novel method for multiple workpieces.

[0023] In another design, multiple workpieces of the same type are manufactured simultaneously in multiple manufacturing areas on a production platform during a combined manufacturing process, wherein a second dataset is used to determine and use uniquely modified machining parameters for each of these workpieces.

[0024] This design allows for the cost-effective manufacture of multiple workpieces of the same type with high efficiency and dimensional accuracy.

[0025] In another design, a second dataset is used to modify the first dataset, resulting in a modified first dataset, which is used to move the structured tool relative to the production platform.

[0026] In some preferred embodiments, the first dataset contains CAD data of the workpiece to be manufactured. In this design, a second dataset can be used to modify this CAD data so that the workpiece layer actually manufactured in the manufacturing area has the desired dimensional accuracy and reproducibility. To a certain extent, the second dataset is used to distort the CAD data uniquely and in relation to the manufacturing area, thereby providing a uniquely modified CAD dataset for each manufacturing area. Depending on the selected manufacturing area, the workpiece layer is manufactured on the production platform using the corresponding uniquely modified CAD dataset. The advantage of this design is that the position-related correction of the workpiece layer can be performed "very early" in the manufacturing process and is largely independent of the hardware of the equipment used. Therefore, the novel method and novel equipment can be implemented very easily and cost-effectively and can be retrofitted from existing equipment. Particularly advantageously, the modification of the first dataset can be performed entirely before manufacturing step c).

[0027] In another design, a first control signal is determined based on a first dataset, which enables the structured tool to move relative to the production platform. The first control signal is then modified based on a second dataset to generate a modified control signal, which is used to move the structured tool relative to the production platform.

[0028] In designs that can be used as alternatives or supplements to the above-described design, correction for position-dependent, unique warpage is achieved by means of modified control signals. This is particularly advantageous for control signals used to manipulate structured tools. This design is especially advantageous if the control of the structured tool is performed using unique calibration data, i.e., if different control signals are generated based on a defined CAD dataset in relation to the equipment used and / or the current environmental parameters. In embodiments of this design, the structured tool is moved relative to the production platform in a closed-loop manner, and the modification of the first control signal may include modification of the drive current or operating voltage.

[0029] In another design, prior to step c-), multiple defined test objects are manufactured layer by layer on a production platform in a spatially distributed manner, wherein the second dataset is determined by means of these multiple defined test objects.

[0030] In this design, the warpage of a defined material layer relative to the manufacturing area is determined using the layers of the test object. This design allows for the very simple and efficient determination of a second dataset for multiple manufacturing areas. In some preferred embodiments, multiple second datasets are determined, differing in the number and distribution of test objects within the production volume. For example, a first number of second datasets can be determined, where one test object is manufactured on a production platform in another manufacturing area. Thus, the first number of second datasets represents the location-related warpage of the material layer for the case where only one workpiece is manufactured during the manufacturing process. In a further step, a second dataset can be determined where multiple test objects are manufactured simultaneously on the production platform. In this case, the second dataset represents the location-related warpage of the material layer and also represents the correlation between the location-related warpage and the occupancy of the production platform and / or the utilization of the production volume. In some advantageous embodiments, multiple second datasets are obtained, representing multiple different manufacturing scenarios, where the different manufacturing scenarios differ in the number and spatial distribution of test objects within the production volume. Therefore, advantageously, for additive manufacturing of a particular workpiece, the second dataset that most closely approximates the current manufacturing scenario in terms of the number and distribution of workpieces can be selected from these multiple second datasets accordingly. This design can significantly improve the dimensional accuracy and reproducibility of additive manufacturing workpieces.

[0031] In another design, the plurality of defined test objects each have a defined longitudinal extension dimension perpendicular to the production platform.

[0032] In this design, the defined test objects can advantageously each have a rod-shaped element, which is manufactured layer by layer from bottom to top on the production platform. This design allows for the determination of position-related variations during the processing sequence in a very simple and efficient manner. Position-related warping that may occur during the layer sequence can result from increased cumulative heat input to the workpiece as the number of workpiece layers increases, and from density variations that may occur due to crystallization. Using test objects with correspondingly defined longitudinal extension dimensions allows for the determination of such variations in a very simple and efficient manner after the test objects are removed from the production platform.

[0033] In another design, the plurality of defined test objects each have a defined longitudinal extension dimension parallel to the production platform.

[0034] In this design, the test object can advantageously have individual rod-like elements that extend generally parallel to the production platform. In some embodiments, the defined test object has rod-like elements that span one or more planes parallel to the production platform. In some embodiments, the test object comprises a structure with rods extending orthogonally to each other, some of which extend parallel to the production platform, and at least one other rod extending perpendicular to the production platform. This design allows for the simple and efficient determination of position-related warpages parallel to the production platform and (in a preferred embodiment) in three spatial directions orthogonal to each other. Thus, for multiple unique, position-related warpages, a second dataset can be determined simply and efficiently. For multiple manufacturing zones and processing parameters, the dimensional accuracy and reproducibility of the workpiece can be improved.

[0035] In another design, unique codes are created for each of the multiple defined test objects, each unique code representing a corresponding manufacturing area on the production platform, and these unique codes are used to determine the second dataset.

[0036] In this design, the defined test objects differ from each other in that the corresponding manufacturing areas can be inferred from the respective test objects. Unique coding, for example, can include bumps and depressions that encode information about the corresponding manufacturing areas on the production platform in the form of barcodes or QR codes. In another design, multiple test objects can be manufactured using a shared holding structure, where the corresponding manufacturing areas are encoded at their respective positions within the shared holding structure. This design facilitates the determination of a second dataset and contributes to the efficient implementation of novel methods and equipment.

[0037] In another design, multiple defined test objects are measured separately using measuring equipment to determine unique test object dimensions, wherein a second dataset is determined based on the test object dimensions.

[0038] In some preferred embodiments, a second dataset is automatically determined based on the size of the test object. Advantageously, a unique code can be associated with a unique test object size. In some embodiments, the measuring device can be an integrated measuring device of a novel device. In other embodiments, the measuring device can include a fixed or mobile 3D scanner used to measure the defined test object after it has been removed from the production platform. In some advantageous embodiments, the test object can be placed in a special test object holder that ensures a defined and reproducible test object position during measurement. The unique test object size can be compared with the target size of the test object (especially in the form of CAD data) to determine the unique, position-related warpage of the workpiece layer. This design allows for highly efficient determination of a second dataset or multiple second datasets representing multiple position-related warpage and machining scenarios.

[0039] In another design, the manufacturing area on the production platform is selected based on a second dataset.

[0040] In some embodiments of this design, the selection of the manufacturing area may involve choosing a specific second dataset from multiple second datasets that best approximates the current manufacturing scenario of the workpieces to be manufactured in terms of workpiece size and / or quantity. Thus, based on the selected second dataset, a manufacturing area on the production platform can be selected that is expected to provide particularly high dimensional accuracy and / or reproducibility for the current manufacturing scenario. This design advantageously contributes to improving the dimensional accuracy and reproducibility of additively manufactured workpieces because the unique positioning and spatial distribution of the workpieces to be manufactured can be optimized in a simple manner.

[0041] In another design, the workpiece is measured using a measuring device after manufacturing is complete to determine unique workpiece dimensions, and a second dataset is modified based on these unique workpiece dimensions.

[0042] In this design, a second dataset is determined using real workpieces from previous manufacturing processes. Therefore, information regarding the dimensional accuracy of workpieces manufactured according to the novel method is considered in future workpiece manufacturing, and this information is fed back into the future manufacturing process, specifically in a closed-loop manner. This design helps establish an adaptive and self-optimizing manufacturing process. Its advantages include taking into account variations in processing parameters over longer time periods and achieving high dimensional accuracy and reproducibility overall over longer production cycles.

[0043] In another design, in step c), the defined material layer is cured using a structuring tool.

[0044] In this design, structuring tools are configured to selectively bond flowable and / or loose materials (especially metal or plastic particles) together to solidify them. Therefore, this design relates to methods and apparatus for additive manufacturing of workpieces, where individual workpiece layers can take on virtually any shape. In such methods, a specific degree of position-dependent warping may occur. Therefore, this design facilitates achieving high dimensional accuracy and reproducibility of workpieces in such methods (especially selective laser sintering and selective laser melting).

[0045] It should be understood that, without departing from the scope of the invention, the above features and the features set forth below can be used not only in the corresponding combinations given, but also in other combinations or individually.

[0046] Embodiments of the invention are illustrated in the accompanying drawings, which are described in detail below. In the drawings:

[0047] Figure 1 A schematic diagram of an embodiment of the novel device is shown, in which multiple workpieces are to be manufactured;

[0048] Figure 2 Show Figure 1 The equipment contains multiple defined test objects;

[0049] Figure 3 Showing according to Figure 2 A schematic diagram of an embodiment of the test object;

[0050] Figure 4 A schematic diagram illustrating embodiments of the novel method and novel device is shown;

[0051] Figure 5 A flowchart illustrating embodiments of the novel method is shown; and

[0052] Figure 6 Another flowchart illustrating an embodiment of the novel method is shown.

[0053] exist Figure 1 In this drawing, embodiments of the novel apparatus are generally indicated by reference numeral 10. The apparatus 10 has a production platform 12 on which workpieces 14, namely three exemplary workpieces 14a, 14b, and 14c, are additively manufactured. Workpieces 14a, 14b, and 14c are constructed layer by layer from bottom to top in a chronological sequence, wherein new material layers are correspondingly manufactured on existing workpiece layers. Figure 1 In the figure, the material layer currently at the top is indicated by reference numeral 16. The workpiece layer further down is indicated by reference numeral 18.

[0054] In the illustrated embodiment, the workpiece layers 18 are each made of powdered material 20. Material 20 is located in a reservoir 22 and can be distributed from the reservoir onto the production platform 12 using a layer-forming tool. Figure 1 The simplified diagram illustrates a scraper 24 that can be moved in the direction of arrow 26 to distribute a new material layer 16 containing powdered material 20 onto the production platform 12 and the already manufactured workpiece layer 18. The powdered material 20 can then be selectively melted and / or fused using a structuring tool and thus solidified into a new workpiece layer. According to... Figure 1 In one embodiment, the structuring tool includes a laser 28 that generates a laser beam 30. As in... Figure 1 As indicated by the circular double arrow, the laser beam 30 can be moved relative to the production platform 12 and thus relative to the material layer 16. To facilitate the fabrication of new material layers using the scraper 24, the reservoir 22 can be moved upward in the direction of arrow 32. Alternatively or supplementarily, the production platform 12 can be lowered in the direction of arrow 34.

[0055] In such a device 10, during the manufacturing process, uncured powder particles are typically retained on the production platform 12 and form a generally closed-loop powder bed, which is not shown here for clarity. The workpiece layer 18 of the workpiece 14 is embedded in the powder bed until the uncured powder material is removed from the production platform 12 at the end of the manufacturing process and the workpiece 14 is exposed. Especially in the case of workpieces made from plastic granules / polymers, the workpiece can (different from the illustration here) be held in the powder bed without direct contact with the production platform 12.

[0056] Unlike the embodiments shown herein, in other embodiments, device 10 may have an electron beam or other structuring tool to selectively fabricate workpiece layers 18 on production platform 12. In some embodiments, material 20 comprises metal powder particles. In other embodiments, material 20 may comprise plastic particles (e.g., made of polyamide). Furthermore, in other embodiments, the structuring tool may apply workpiece material locally and selectively, for example, by means of an inkjet printer or by means of a powder nozzle that jets powdered material.

[0057] like Figure 1 As shown, each workpiece 14 has a lateral workpiece dimension 36 that is smaller than the corresponding lateral platform dimension 38. Here, the term "lateral dimension" refers to the length and / or area of ​​the upwardly increasing stack transversely to and particularly perpendicular to the workpiece layer 18. Correspondingly, the lateral dimension here can be length and / or area information.

[0058] The reference numeral 40 denotes a manufacturing area on the production platform 12, in which workpieces 14co are manufactured layer by layer. Depending on the lateral dimensions of the workpieces to be manufactured, one or more manufacturing areas 40 may be defined on the production platform 12. As noted at the outset, the material layer 16 and the workpiece layer 18 produced therefrom may have unique warpages associated with the corresponding manufacturing area 40 in which these layers are manufactured. These unique warpages may include dimensional deviations in the lateral direction, height (perpendicular to the production platform 12), and / or deviations in the flatness of these layers. These unique warpages may be related to both the lateral position of the corresponding manufacturing area 40 relative to the production platform 12 and the height of the corresponding layer relative to the production platform 12. In some cases, the layer thickness perpendicular to the production platform 12 may vary, in particular, depending on the corresponding manufacturing area 40. Correspondingly, embodiments of the novel method implement correction mechanisms to achieve the most consistent dimensional accuracy and reproducibility of the workpieces 14.

[0059] Device 10 includes a control unit 42 in a manner known per se, shown herein as having a processor 44 and a controller 46. The controller 46 generates control signals and, in particular, controls the movement of the laser beam 30 relative to the production platform 12. Furthermore, the controller 46 can control the movement of the production platform 12 in the direction of arrow 34, the movement of the storage 22 in the direction of arrow 32, and / or the movement of the scraper 24 in the direction of arrow 26. In some embodiments, the controller 46 includes one or more drive stages that manipulate the laser 28 and various electric drive devices (not shown herein). The processor 44, here representing a data processing unit, determines appropriate control commands for the controller 46 and / or the aforementioned drive stages. In some embodiments, the processor 44 can be implemented using a commercially available PC running a suitable operating system such as Windows, OSX, Linux, etc. Thus, a computer program (not shown herein) is run by means of the processor 44 to utilize... Figure 1 Examples of implementing the novel method using equipment.

[0060] Reference numeral 48 denotes a first memory in which a first dataset 50 is stored. Reference numeral 52 denotes a second memory in which a second dataset 54 is stored. Memory 48 and 52 can be internal or external memory of a data processing unit (shown herein as processor 44). For example, memory 48 and 52 can be storage areas of the internal working memory (RAM) of the data processing unit shown as processor 44. Alternatively or additionally, memory 48 and 52 can be internal or external hard disk storage or storage areas on such hard disks. In principle, memory 48 and 52 can also be hard disk storage connected to processor 44 via a network connection (e.g., Ethernet connection).

[0061] In some preferred embodiments, the first dataset 50 is a CAD dataset that defines the workpiece to be manufactured in a plurality of horizontally arranged workpiece layers 18 arranged vertically above each other. Alternatively or additionally, the first dataset 50 may contain general CAD data that describes the workpiece to be manufactured in a general sense, i.e., without describing the horizontally arranged workpiece layers. Thus, the processor 44 can determine the corresponding dataset having the plurality of horizontally arranged workpiece layers by means of the first dataset from the memory 48. In other embodiments, the first dataset may contain reverse engineering data and / or data from computed tomography images, i.e., data obtained from an existing model or a real design template. In all preferred embodiments, the first dataset 50 defines the workpiece 14 to be manufactured and its target characteristics.

[0062] The second dataset 54 represents the unique warpage associated with the corresponding manufacturing region 40 of the defined material layer or workpiece layer. According to embodiments of the novel method, the second dataset enables preemptive correction of unique, location-related warpage during manufacturing. In some advantageous embodiments, the second dataset 54 includes interpolation parameters that enable unique correction of location-related warpage even if the currently selected manufacturing region 40 does not perfectly match a previously derived manufacturing region using a test object.

[0063] Figure 2 Show Figure 1 The equipment 10, wherein multiple defined test objects, rather than workpieces 14a, 14b, 14c, are manufactured in manufacturing area 40 on production platform 12. Furthermore, the same reference numerals denote... Figure 1The same elements are present. The test object 56 can be used to determine the second dataset 54 in the following manner. Advantageously, the defined test object is manufactured in a manufacturing process that precedes the manufacturing process of the workpiece 14 in a manner substantially the same as that of the workpiece 14 (the difference being that the current second dataset 54 is only available after the manufacture and measurement of the test object 56). Therefore, the test object 56 is constructed layer by layer from the powdered material 20 from bottom to top, especially here by means of a laser beam 30.

[0064] Figure 3 Shown in a slightly larger diagram Figure 2 An embodiment of the test object. Here, the test object 56 has a defined longitudinal extension dimension 58 parallel to the production platform 12 and a defined longitudinal extension dimension 60 perpendicular to the production platform. In a preferred embodiment, the test object 56 has rod-shaped elements 62, 64, and 66 extending in three spatial directions orthogonal to each other, wherein in this case, rod-shaped elements 62 and 64 extend parallel to the production platform 12, while rod-shaped element 66 extends perpendicular to the production platform. Each of the rod-shaped elements 62, 64, and 66 has a defined target dimension, which can be stored, for example, in the form of CAD data in a first memory 48. Figure 2 In this process, the actual extended dimensions of the rod elements 62, 64, and 66 typically differ from the target dimensions depending on the corresponding manufacturing area 40. The difference between the actual dimensions and the corresponding target values ​​allows for the determination of unique, position-related warpages in the three spatial directions defined by the rod elements 62, 64, and 66. Correspondingly, in a preferred embodiment of the novel method, multiple test objects 56 are manufactured simultaneously or sequentially in corresponding manufacturing areas 40 on the production platform 12, and subsequently measured to determine the corresponding position-related warpages. Advantageously, not only the longitudinal dimensions of the rod elements 62, 64, and 66 can be measured, but also the relative spacing and / or angles between them. For example, the relative spacing between rod elements 62 and 62' can represent position-related warpage perpendicular to the production platform 12 during manufacturing, even if the longitudinal extended dimension 60 of the test object 56 is within the range of the corresponding target value. This may be especially true when the positional warpage of a defined material layer is related to and / or varies with the corresponding height of the material layer in the production volume during manufacturing.

[0065] In some embodiments, the test object 56 may be manufactured with a corresponding unique code 68, which makes it possible to subsequently identify the corresponding manufacturing area 40 by means of the test object 56 itself.

[0066] like Figure 4As shown, in a preferred embodiment of the novel method, after manufacturing is complete, the test object 56 is measured using measuring device 70 to determine unique test object dimensions 58, 60 and their associated deviations from target dimensions. The acquired measurement data is used to determine a second dataset 54. In some embodiments of the novel method, the second dataset 54 can be used to modify the first dataset 50 (which, for example, represents the CAD data of the workpiece 14 to be manufactured), as shown in... Figure 4 As indicated by reference numeral 72 in the accompanying drawings. Correspondingly, in some embodiments, a modified first dataset 74 can be determined, which to some extent represents a unique, location-dependent pre-distortion related to the workpiece to be manufactured and the corresponding selected manufacturing area. Subsequently, the modified first dataset can be used to determine the control signals for the controllers of the structured tools 28, 30. Alternatively or supplementarily, a second dataset 54 can be used to determine the modified control signals for different manufacturing areas. In some embodiments, the device 10 may include a measuring device 70 as a mobile (e.g., handheld) 3D measuring device or as a fixed measuring device. The determination of the modified first dataset 74 and / or the modified control signal 76 is preferably performed automatically by means of measurement data of a plurality of coded test objects 56 and by means of the corresponding current first dataset 50 representing the workpiece 14 to be manufactured. The determination of the modified first dataset 74 and / or the modified control signal 76 can be performed by means of a processor 44 and / or in a controller 46.

[0067] Correspondingly, embodiments of the novel method may include, as in Figure 5 The method steps are simplified below. According to steps 80 and 82, test objects are manufactured in multiple manufacturing areas 40 on the production platform 12. According to step 80, a single test object can be manufactured on the production platform 12 in a selected manufacturing area, and subsequently, according to step 82, another test object can be manufactured in another manufacturing process and in another manufacturing area. Alternatively or supplementarily, multiple test objects can be manufactured simultaneously on the production platform in one manufacturing process. In a preferred embodiment, multiple test objects are manufactured in multiple manufacturing processes and in multiple manufacturing areas, wherein the selection of the corresponding manufacturing area and / or the coverage density of the test objects on the production platform 12 can vary between one manufacturing process and the next. After all desired test objects are manufactured in steps 80 and 82, according to step 84, the test objects are measured individually to determine the location-related and / or filling-related warpage of the corresponding material layer. According to step 86, the acquired information is integrated into a second dataset and stored in memory 52.

[0068] like Figure 6A preferred embodiment of the novel method and apparatus shown uses a second dataset that can be read from memory 52 according to step 88. According to step 90, a first dataset is also obtained, which may, for example, represent CAD data of the workpiece to be manufactured. In some embodiments, according to step 92, the second dataset is used to select a manufacturing area for the workpiece to be manufactured. In some embodiments, for this purpose, a suitable second dataset can be selected from multiple second datasets representing different manufacturing scenarios, the second dataset being closest to the manufacturing scenario for the current workpiece 14 in terms of the number and / or size of the workpieces to be manufactured on the production platform. According to step 94, the second dataset is used to determine control signals for controlling the structured tool. The control signals include, to some extent, a pre-distortion of the workpiece to be manufactured, which is selected such that the unique, position-dependent warpage of the material layers is compensated and the manufactured workpiece corresponds to target data according to the first dataset having high dimensional accuracy and reproducibility.

[0069] According to steps 96 and 98, workpieces are now manufactured layer by layer in the workpiece layers that are successively above and below each other. According to step 100, in some preferred embodiments, the manufactured workpieces are measured after manufacturing is completed to verify dimensional accuracy and reproducibility. Based on the measured unique workpiece dimensions, the second dataset can be updated according to step 102, so that the correspondingly updated second dataset can be obtained in future manufacturing processes.

Claims

1. A method for additive manufacturing of a workpiece (14) having a lateral workpiece dimension (36), the method having the following steps: a) acquiring a first data set (50) defining the workpiece (14) in a plurality of workpiece layers (18) arranged on top of one another; b) selecting a manufacturing area (40) on a production platform (12) having a lateral platform dimension (38) larger than the lateral workpiece dimension (36), wherein the manufacturing area (40) defines a section of the production platform (12) on which the workpiece (14) shall be manufactured layer by layer; c) producing a defined material layer (16) in the manufacturing area (40) on the production platform (12) using the first data set (50), wherein the material layer (16) is utilized to produce a defined workpiece layer (18) formed by a plurality of the workpiece layers arranged on top of one another; and d) repeating the step c) wherein further defined workpiece layers (18) formed by a plurality of the workpiece layers arranged on top of one another are produced, acquiring a second data set (54) representing a warping of the defined material layer (16) in relation to the manufacturing area (40) before the step c), and producing the defined material layer (16) using the first data set (50) and using the second data set (54). Producing the defined material layer (16) by means of a structuring tool (30), moving the structuring tool relative to the production platform (12) using the first data set (50) and using the second data set (54). Modifying the first data set (50) using the second data set (54) resulting in a modified first data set (74), wherein the structuring tool (30) is moved relative to the production platform (12) according to the modified first data set (74). Determining a first control signal from the first data set (50) with which the structuring tool (30) can be moved relative to the production platform (12), wherein the first control signal is modified according to the second data set (54) resulting in a modified control signal (76), and wherein the structuring tool (30) is moved relative to the production platform (12) according to the modified control signal (74). Simultaneously manufacturing a plurality of workpieces (14a, 14b, 14c) of the same type in different manufacturing areas (40) on the production platform (12) in a combined manufacturing process, wherein a uniquely modified process parameter is determined and used for each of the workpieces (14a, 14b, 14c) using the second data set. characterized in that Manufacturing a plurality of defined test objects (56) layer by layer in a manner spatially distributed on the production platform (12) before the step c), wherein the second data set (54) is determined by means of the plurality of defined test objects (56).

2. The method of claim 1, wherein, ​ 3. The method of claim 2, wherein, ​ 4. The method according to claim 2 or 3, characterized in that, ​ 5. The method according to one of claims 1 to 3, characterized in that, ​ 6. The method according to one of claims 1 to 3, characterized in that, ​ 7. The method of claim 6, wherein, The plurality of defined test objects (56) each have a defined longitudinal extension dimension perpendicular to the production platform (12).

8. The method of claim 6, wherein, The plurality of defined test objects (56) each have a defined longitudinal extension dimension parallel to the production platform (12).

9. The method of claim 6, wherein, A unique code (68) is established for the plurality of defined test objects (56) individually, the unique code representing a respective manufacturing area (40) on the production platform (12), wherein the second data set (54) is determined using the unique code (68).

10. The method of claim 6, wherein, The plurality of defined test objects (56) are each measured with a measuring device (70) to determine unique test object dimensions (58, 60), wherein the second data set (54) is determined from the test object dimensions.

11. The method according to one of claims 1 to 3, characterized in that, A manufacturing area (40) on the production platform (12) is selected in accordance with the second data set (54).

12. The method according to one of claims 1 to 3, characterized in that, The workpiece (14) is measured with a measuring device after the manufacturing is completed to determine unique workpiece dimensions, wherein the second data set (54) is determined from the unique workpiece dimensions.

13. The method of claim 2 or 3, wherein, In step c), the defined material layer (16) is solidified with the aid of the structuring tool (30).

14. An apparatus for additive manufacturing of a workpiece (14) having a lateral workpiece dimension (36), the apparatus having a production platform (12) having a lateral platform dimension (38) which is larger than the lateral workpiece dimension (36), a structuring tool (30) which is movable relative to the production platform (12), a first memory (48) which is configured to acquire a first data set (50) which defines the workpiece (14) in a plurality of workpiece layers (18) arranged above one another, and a control unit which is configured to use the first data set to move the structuring tool (30) relative to the production platform (12) in order to produce a plurality of material layers (16) layer by layer in a manufacturing area (40) on the production platform (12), wherein each material layer (16) of the plurality of material layers is used to produce a defined workpiece layer (18) formed by a plurality of the workpiece layers arranged above one another, characterized in that A second memory (52) is configured to acquire a second data set (54), wherein the second data set (54) represents a warping of the defined workpiece layer (18) in relation to the manufacturing area (40), and wherein the control unit (42) is configured to move the structuring tool (30) relative to the production platform (12) using the first data set (50) and using the second data set (54).

15. Computer program product having a program code configured to perform the method according to one of claims 1 to 13 when the program code is run on a control unit (42) of an apparatus according to claim 14.

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