Method for generating control data for additively manufacturing a component
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- EOS GMBH ELECTRO OPTICAL SYST
- Filing Date
- 2024-08-01
- Publication Date
- 2026-06-17
Smart Images
Figure EP2024071918_13022025_PF_FP_ABST
Abstract
Description
[0001] Method for generating control data for additive manufacturing of a component
[0002] The invention relates to a method for generating control data for the additive manufacturing of a component. The invention further relates to corresponding control data, a manufacturing method for the additive manufacturing of a component, a control data generation device, a control device of a device for additive manufacturing, and such a device.
[0003] One challenge in additive manufacturing is creating components with a very large surface area relative to their volume. A high surface area-to-volume ratio has the advantage that chemical or physical processes can proceed faster and more efficiently in such structures, for example, when these components are used as catalysts, mixing elements, or heat exchangers.
[0004] Components are often provided with periodic structures, e.g., structures known in differential geometry as "triply periodic minimal surfaces" (TPMFs). These are three-dimensional surface structures that are translationally invariant under a three-dimensional lattice. A special example of such TPMFs are gyroids according to the mathematical formula: sin x cos y + sin y cos z + sin z cos x = 0 (1)
[0005] In addition to a very high surface-to-volume ratio, gyroid structures in particular have very good structural mechanical properties. They are self-supporting and essentially have no edges. Therefore, they can also be used as lattice structures in a component, which is advantageous for lightweight construction. It should also be noted that gyroids, in particular, have two separate channels or chambers, which is advantageous for heat exchangers or chemical processes in liquids.
[0006] Components with a structure are currently manufactured by replicating a unit cell in all spatial directions, or by creating a three-dimensional periodic pattern of a structure and then intersecting it with the component volume based on a logical AND operation. One problem with current structure generation, such as gyroid structures, is that there is limited design flexibility because a unit cell is fundamentally not modified but merely multiplied. Thus, circular and complex components, in particular, cannot be satisfactorily created from triple-period minimal surfaces.
[0007] In addition, adapting structures to the overall component geometry is only possible with great effort or not at all.
[0008] It is an object of the present invention to provide methods for generating control data for the additive manufacturing of a component and a suitable control data generation device therefor in order to provide components with a (periodic) structure.
[0009] This object is achieved by a method for generating control data according to patent claim 1, control data according to patent claim 10, a manufacturing method according to patent claim 11, a control data generating device according to patent claim 12, a control device for a manufacturing device according to patent claim 13, and a device for the additive manufacturing of components (also called “manufacturing device” for short) according to patent claim 14.
[0010] A method according to the invention serves to generate control data for the additive manufacturing of a component in a manufacturing process in which build-up material, preferably comprising a metal powder, is built up layer by layer using a device in a build area by selectively solidifying the build-up material by irradiating the build-up material with at least one energy beam. It thus serves, in particular, to generate control data for a corresponding device.
[0011] The procedure includes the following steps:
[0012] - Providing a component data set comprising data on the three-dimensional shape of a component (to be manufactured) and data on a three-dimensional structural area (within) the component which is intended to be provided with a structure,
[0013] - Providing a structure data set comprising at least data on the structure of a unit cell of a periodic structure,
[0014] - Predetermining a grid of three-dimensional grid cells in the structural area, wherein the unit cell can be spatially arranged in the grid cells, preferably wherein the grid cells are homeomorphic to the unit cell, wherein preferably at least one grid cell deviates from the external shape of the unit cell,
[0015] - Fitting the unit cell into each grid cell so that the shape of the unit cell corresponds to the shape of the respective grid cell, and filling the grid cells with a fitted unit cell to form a structure,
[0016] - Creation of control data for the layer-by-layer construction of a component whose structural area is structured with the structure,
[0017] - Output of the control data to a device for the additive manufacturing of a component.
[0018] Component data sets are known in the art. They can be CAD data sets of the component (CAD: from the English "computer-aided design") or other data sets from which the shape and structure of the component can be derived. A component data set must at least include data on the 3D shape of a component (to be manufactured) as well as data on a three-dimensional structural area (preferably within) the component. Data on the three-dimensional shape of a component is known to those skilled in the art (e.g., the CAD data).
[0019] Even if it is preferred that the component data set specifies the final shape (and size) of the component, i.e. how it is to be manufactured later, in some cases it is preferred that the component data set can be changed subsequently (before manufacturing and especially after structuring), e.g. enlarged or reduced.
[0020] The structural region is an area (volume) inside the component where the component is intended to be provided with a (periodic) structure, which may well include the walls of the component. The component does not yet contain this structure; rather, this structure is first created using the method according to the invention. The structural region may well extend across the entire component. In practice, however, it usually only extends over part of the component.
[0021] Periodic structures are, in principle, known in the art. These are structures with repeating patterns formed from so-called "unit cells" that are duplicated and arranged side by side and one behind the other. It should be noted that a periodic structure fitted (using the invention) is still fundamentally periodic, even if the size of the unit cells should fluctuate across the pattern. Preferred periodic structures are the structures with triple-periodic minimal surfaces mentioned in the introductory section, which can also be referred to as TPMF structures. A particularly preferred TPMF structure is the aforementioned gyroid structure.
[0022] Even though periodic structures are known, it is not yet known and not trivial to adapt these structures to the shape of any domain.
[0023] Since a periodic structure is a periodic pattern of unit cells, essentially only data on the structure of a unit cell is necessary to know the internal shape of the structure. A structure data set therefore only requires information on one unit cell. This data can, for example, include a mathematical function (e.g., sin x cos y + sin y cos z + sin z cos x = 0 for a gyroid unit cell) or a CAD model of a unit cell (e.g., comprising a sheet). During production, these surfaces are manufactured as thin walls, whereby the following inequality with the (preferably positive) coefficients d and e can be chosen to calculate the walls: d < sin x cos y + sin y cos z + sin z cos x < e. (2)
[0024] The grid specifies how the unit cells must be arranged. This means that the structural data set containing the unit cell is provided and the grid is specified in such a way that the unit cell can be arranged spatially or geometrically within the grid cell. When providing the structural data set or specifying the grid, it is not necessary to include a step in which the unit cell or grid cells are changed and / or the unit cell and grid cells are adapted to one another. The fact that the unit cell can be arranged spatially or geometrically within the grid cells does not mean that a spatial or geometric change or adaptation of the unit cell and / or grid cells must take place when providing the structural data set or when specifying the grid. In particular, the grid is gapless, which can be achieved simply by choosing the structural region.The structural area is a volume (especially within) the component that is intended to be provided with a structure. For ease of understanding, one can imagine that the entire structural area is represented by a gapless grid. "Gaps" in the grid, if they are intended to be present, are represented by interruptions in the structural area (which could then essentially correspond to two structural areas). It is possible to divide the structural area into grid cells, create a grid, and fit this into the structural area, possibly by reshaping the grid cells, or use a logical AND function to cut out a part of the grid that corresponds to the structural area (as the intersection of the grid and the structural area). A regular grid is preferably modified by a homeomorphic function, e.g.by stretching and / or compressing its grid cells, thereby adapting it to the structural area.
[0025] It is preferred for the grid to be formed from three-dimensional grid cells that are homeomorphic to the unit cell. The unit cell can therefore be transformed into any grid cell by means of a homeomorphism (also called topological mapping or topological isomorphism). From a topological point of view, the unit cell and the grid cells are therefore preferably of the same type. A homeomorphism can be visualized as stretching, compressing, bending, distorting, and twisting of an object. Preferably, a rearrangement of edges and corners of the grid cell outside of a homeomorphic change is therefore not permitted. When providing the structural data set or when specifying the grid, the unit cell does not necessarily have to be transformed into the grid cell. The fact that the unit cell and the grid cells are homeomorphic (i.e.The fact that the unit cell can be transformed into the grid cells using a homomorphism does not mean that the unit cells will be transformed into the grid cells when the structural data set is provided or the grid is specified. A transformation (or fitting, as explained below) can take place in a different step. Even if a transformation (fitting) takes place in a different step, it does not necessarily have to be done using a homomorphism.
[0026] For a cubic unit cell, there are lattice cells into which a cube can be fitted using a homeomorphism. For a unit cell in the shape of a tetrahedron, there are correspondingly shaped lattice cells. Essentially, one can imagine that the lattice and structure correspond to a Krista II structure, and the lattice cells and unit cell are unit cells of the Krista II structure.
[0027] It is preferred that at least one grid cell deviates from the external shape of the unit cell. This means that the unit cell is deformed, e.g. distorted, when fitted into this grid cell. This does not mean that all grid cells cannot be the same. For example, in the case of a cubic unit cell and a grid in the shape of a ring, where the grid cells are identical ring segments, all grid cells could be the same and all deviate from the shape of the unit cell (because they are wedge-shaped with partially rounded edges). The unit cell can be fitted into each grid cell in different ways and at different phases of the process. The only important thing is that the shape of the unit cell corresponds to the shape of the respective grid cell. The grid is therefore completely filled with unit cells.The simplest approach is to fit the unit cell and then fill the lattice cell with a copy of the correspondingly fitted unit cell, or with a surface or wall structure that corresponds to the fitted unit cell. Here, too, one can imagine a crystal structure whose unit cells are now formed by the unit cells. Thus, the lattice collapses with the special surface structure and now forms a structure.
[0028] Depending on the application, the unit cell and the grid cells may have the same shape and size. In this case, the unit cell is inserted (e.g., copied) into the grid cells during fitting. In practice, however, a change in size (deformation or fitting) is probably the norm, since the unit cell and the grid cells typically come from different data sets.
[0029] Fitting the unit cell into the grid cells can certainly occur before specifying the grid in the structural domain. The grid can be "collapsed" with the unit cells and only then fitted into the structural domain, or a volume of the grid can be excised for the structural domain. At least in the case where the structural domain is divided into a grid, however, it is preferable to fit the unit cell into the grid cells afterward.
[0030] Fitting a unit cell into a grid cell can be done using simple image registration methods. The respective geometries of the unit cell and the grid cells are known. If a grid cell has been deformed, e.g. scaled, compressed, stretched or distorted in some other way, the unit cell can be deformed in the same way using methods known in the art. In practice, for example, a grid cell can be deformed using a transformation function by deforming the edges and corners. This transformation function can then be extended to points within the grid cell so that a deformation runs continuously through the volume of the grid cell. This technique is used, for example, in what is known as "morphing". The image points (i.e. the surface structure) of the unit cell can then be transformed according to this extended transformation function.Note that fitting a unit cell into a grid cell is equivalent to filling the grid cell with the unit cell. A copy of the unit cell is then present in every grid cell, thus forming a (virtual) structure.
[0031] The surface structure of a unit cell should be viewed as a (thin) volume, i.e., as a wall. It is possible to define the thickness of this wall before or during the fitting of a unit cell into a lattice cell, but also after fitting (e.g., for the entire resulting structure).
[0032] Thus, we now have a solid body according to the component dataset, in which the structural region is structured with a structure. It should be noted that the structural region can also correspond to the entire component, for example, in the case of a heat exchanger. In this case, the component is only created by the lattice filled with unit cells and deformed.
[0033] As indicated above, the component can also only now receive its final manufactured size or shape. To do this, you can initially work with a component data set that represents the basic shape, but can then be changed later. Subsequent changes can be made based on calculations performed on the structured component. For example, you can examine whether the area of the structured component has reached a certain size and, if necessary, the size of the component can be subsequently changed by changing the size of the grid cells and thus also the fitted unit cells. However, the shape of the grid cells can also be changed once again. The preferred procedure for this is to define a new structural area and adapt the (filled) grid to this new structural area.
[0034] The creation of control data from a solid body for its layer-by-layer construction is well known in the state of the art.
[0035] This control data can be output to a device for additive manufacturing of a component via known data interfaces, which is standard in additive manufacturing.
[0036] Control data according to the invention for controlling an additive manufacturing device were created using such a method according to the invention. They differ from control data sets according to the prior art due to the special structuring (particularly within) the component.
[0037] In a manufacturing method according to the invention for the additive manufacturing of a component, build material, preferably comprising a metal powder, is built up layer by layer in a build field by selectively solidifying the build material by irradiating the build material with at least one energy beam according to the control data according to the invention. To create component layers of the component, the energy beam is moved across the build field within defined areas according to these control data.
[0038] A control data generation device according to the invention for generating control data according to the invention for a device for additive manufacturing of a component in a manufacturing process in which build-up material, preferably comprising a metal powder, is built up layer by layer in a build-up field by selectively solidifying build-up material by irradiating the build-up material with at least one energy beam, comprises the following components:
[0039] - a data interface designed to receive a component data set comprising data on the three-dimensional shape of a component (to be manufactured) and data on a three-dimensional structural area (in particular within) the component which is intended to be provided with a structure, and a structural data set comprising data on the structure of a unit cell of a periodic structure,
[0040] - a lattice unit, designed to specify a lattice of three-dimensional lattice cells in the structural region, wherein the unit cell can be spatially arranged in the lattice cells and preferably wherein the lattice cells are homeomorphic to the unit cell, wherein preferably at least one lattice cell deviates from the external shape of the unit cell,
[0041] - a fitting unit designed to fit the unit cell into each grid cell so that the shape of the unit cell corresponds to the shape of the respective grid cell, and filling the grid cells with a fitted unit cell to form a structure,
[0042] - a control data unit designed to create control data for the layer-by-layer construction of a component whose structural area is structured with the structure,
[0043] - a data interface designed to output the control data to a device for the additive manufacturing of a component.
[0044] A control device according to the invention for a device for the additive manufacturing of a component in a manufacturing process in which build-up material, preferably comprising a metal powder, is built up layer by layer in a build area by selectively solidifying build-up material by irradiating the build-up material with at least one energy beam using an irradiation device, is designed to control the device for the additive manufacturing of the component layers of the component according to control data according to the invention. The control device preferably comprises a control data generation device according to the invention.
[0045] A device according to the invention for the additive manufacturing of at least one component in an additive manufacturing process comprises at least
[0046] - a feeding device for applying layers of build material to a build area in a process chamber,
[0047] - an irradiation device for selectively solidifying build-up material by irradiation with at least one energy beam, in particular between the application of two material layers, and
[0048] - a control device according to the invention.
[0049] The control data generation device or method according to the invention can be implemented, in particular, in the form of a computer unit with suitable software. For this purpose, the computer unit can, for example, comprise one or more cooperating microprocessors or the like. In particular, it can be implemented in the form of suitable software program components in the computer unit of a control data generation device or control device. A largely software-based implementation has the advantage that even previously used computer units, in particular control data generation devices and control devices of production devices, can be easily retrofitted by means of a software or firmware update to operate in the manner according to the invention.In this respect, the object is also achieved by a corresponding computer program product with a computer program which can be loaded directly into a memory device of a computer unit, in particular a control data generation device and / or control device, with program sections in order to carry out all steps of the method according to the invention when the program is executed in the computer unit or control data generation device and / or control device. Such a computer program product can, in addition to the computer program, optionally comprise additional components such as, for example, documentation and / or additional components, including hardware components such as, for example, hardware keys (dongles, etc.) for using the software. For transport to the computer unit or control data generation device and / or control device and / or for storage on or in the computer unit orA computer-readable medium, for example a memory stick, a hard disk or another portable or permanently installed data carrier, on which the program sections of the computer program that can be read and executed by a computer unit, in particular the control data generation device and / or the control device, are stored, can serve as the control data generation device and / or the control device.
[0050] Further, particularly advantageous embodiments and developments of the invention emerge from the dependent claims and the following description, wherein the independent claims of one claim category can also be developed analogously to the dependent claims and embodiments of another claim category and, in particular, individual features of different embodiments or variants can be combined to form new embodiments or variants.
[0051] According to a preferred method, the structural data set comprises data on a unit cell, preferably based on the above-mentioned formula (1): sin x cos y + sin y cos z + sin z cos x = 0.
[0052] The unit cell, which can also be referred to here as a "gyroid unit cell", can certainly be formed using this formula, or from surface elements that follow this formula. However, a modification of this formula with the coefficients a, b and c can also be used, with a sin x cos y + b sin y cos z + c sin z cos x = 0, (3) where a, b and / or c can certainly be functions of x, y and z. To form voluminous walls instead of surfaces, the surfaces can be given a certain thickness in a CAD program or the formula can be reformulated into inequalities (cf. formula (2) above) with e > a sin x cos y + b sin y cos z + c sin z cos x > d (4) with the, in particular positive, coefficients d and e. Theoretically, it would also be possible for one of the coefficients to be negative. In this case, the area that would result from an equation with 0 would be next to the wall, so one channel of the gyroid would be larger than the other.
[0053] According to a preferred method, adjacent grid cells share vertices and have identical contact surfaces. This means that the two adjacent surfaces of the grid cells are identical. This means that unit cells abut each other there, resulting in a continuous structure. Gyroid structures would thus have continuous channels.
[0054] According to a preferred method, the symmetry of the unit cell and the lattice cells is cubic, tetragonal, rhombic, or orthorhombic. In principle, the symmetry of a unit cell can correspond to a crystal structure. Preferably, the unit cell is cubic, and the lattice cells are also cubic, or at least distortions of a cubic shape. As stated above, the unit cell should fit into a lattice cell from its basic shape. In this respect, a cubic unit cell fits into a cubic lattice cell, but a tetrahedron does not. However, a tetrahedron can be transformed into a cubic shape using a homeomorphism. It should be noted that a cube is also a rhombus. "Symmetry" here means in particular that the basic structure of edges and vertices (e.g., the number of edges originating at the respective vertices and which vertices are connected to each other by edges) is identical.
[0055] According to a preferred method for fitting the unit cell into a grid cell, the unit cell is deformed such that it corresponds to the shape of the grid cell, preferably by changing the position of corners and the orientation and / or length of edges of the unit cell and / or by curving a side surface and / or an edge. The entire volume of the unit cell is distorted accordingly. Techniques for adapting one volume to another are known in the art. The deformation preferably corresponds to a transformation with which the corresponding grid cell has been transformed.
[0056] The grid cells are preferably arranged regularly in the grid. This embodiment can be easily adapted to a structural region using transformation functions. These transformation functions can be transferred to individual grid cells, even if they affect the entire grid, and thus the unit cell can be deformed accordingly in order to adapt it to the respective grid cells. Alternatively or additionally, the grid cells have an identical size, but it can also be preferred that they have different sizes, preferably with the size decreasing in at least one spatial direction. The grid cells can therefore become smaller in one direction, which then also affects the structure, which likewise has smaller substructures in one direction.
[0057] Alternatively or additionally, the grid cells are longer in at least one spatial direction than in another. They are therefore elongated.
[0058] Alternatively or additionally, the grid cells are increasingly twisted around at least one spatial axis along this axis. This would correspond, for example, to a helical shape.
[0059] Alternatively or additionally, the grid cells are increasingly distorted with respect to at least one spatial axis along this axis in at least one other spatial axis. This would correspond, for example, to a grid whose grid cells are increasingly distorted the higher they are located.
[0060] All this applies to at least a partial area of the grid and occurs in particular after a transformation of the grid or after the subdivision of a structural area.
[0061] According to a preferred method, at least part of the grid is specified by subdividing the structural region and / or a specified grid is adapted by transformation to the shape of at least part of the structural region. These features can be present individually or combined, e.g., by first subdividing a complex structural region into a simple grid (with overhangs at the edge of the structural region) and then adapting its grid cells in the edge region of the structural region to the exact shape of the structural region.
[0062] Regarding the fitting of the unit cell into the grid cells, three cases are preferred:
[0063] 1) When subdividing the structural area, the structural area is first divided into a grid and then the unit cell is adapted to the grid cells.
[0064] 2) A grid is created (independent of the structural domain), then fitted to the structural domain, and then the unit cell is fitted to the grid cells. 3) A grid is created (independent of the structural domain), then the unit cell is fitted to the grid cells, and the grid, along with the filled grid cells, is then fitted to the structural domain.
[0065] When combining both alternatives, the unit cell can be fitted into the grid cells before or after the adjustment.
[0066] In practice, for example, the component (or its 3D representation) is divided in such a way that at least one structural area is created, the grid is specified by the subdivision of the structural area or the shape of a grid is fitted into the shape of the structural area and the unit cell is distorted during or after the process according to the grid cells and inserted into them.
[0067] Preferably, after the structure has been formed, the structural region is modified along with the structure. This is preferably done by deforming the grid cells of the grid (if necessary again) and / or changing their size. The structural region can certainly correspond to the entire component, allowing the component to be adapted to specific requirements. For example, in the case of a heat exchanger, the absolute size of the surface can play a role, but its absolute external dimensions have a certain degree of flexibility. It is then possible to structure the general shape of the heat exchanger (component and structural region at the same time) according to the method, then calculate the surface area of the resulting structure and then, if necessary, adjust the size to create a surface with the desired size. To do this, the grid can be deformed a first time and then the grid (filled with unit cells) can be deformed a second time.
[0068] According to a preferred method, a subdivision area that encompasses the structural area is divided into a grid (in particular a gapless one, see above). This grid is the specified grid. The subdivision area can certainly be larger than the component. Alternatively, a grid can be specified that extends at least over the structural area (and beyond its boundaries). After fitting, the filled grid cells are separated within the structural area. It is particularly preferred that the unit cell is first fitted into each grid cell of the grid and then the grid cells filled with the unit cell are separated within the structural area. Separation is preferably carried out by means of a logical AND function between the structural area and the grid. The intersection of the structural area and the grid is therefore formed orA volume of the lattice corresponding to the structural region is cut out. Fitting the unit cell beforehand, i.e., filling the lattice before separation, is advantageous because separation can also divide lattice cells, meaning their unit cell could be cut. It is easier to cut a fitted unit cell than to insert a unit cell into a cut lattice cell.
[0069] According to a preferred method, in addition to the geometric shape, other parameters of the unit cell are also modified during the fitting of the unit cell into a grid cell. These parameters are, in particular, the wall thickness within the unit cell and / or coefficients of a TPMF function that determines the unit cell. For example, if one considers a gyroid unit cell according to the formula e > a sin x cos y + b sin y cos z + c sin z cos x > d, the wall thickness can be specified with d and e, and a modification of the shape can be achieved by changing the coefficients a, b, and c of the TPMF function.
[0070] The coefficients a, b, and c distort the basic structure of the body specified by sine and cosine functions. The coefficients e and d specify the boundaries of the enclosed volume. Thus, d and e can be used to specify a local extension, dependent on a position (coordinate), and thus a distance from the surface can be generated specifically depending on a location.
[0071] The coefficients can be constant, but different in different grid cells. However, it is preferred that the change in the parameters depends on a spatial direction within the grid cell. This means that a change can become stronger or weaker across the unit cell. Since the change can be adopted by neighboring grid cells, a change (e.g., in wall thickness) can increase or decrease or fluctuate across the entire grid (e.g., the walls can become thicker in one direction). The coefficients can therefore depend on x, y, and z, where x, y, and z can be global coordinates across the entire grid or local coordinates within a grid cell. For a gyroid unit cell, the following can therefore apply: e(x, y, z) > a(x, y, z) sin x cos y + b(x, y, z) sin y cos z + c(x, y, z) sin z cos x > d(x, y, z).The change should be continuous at the transition to neighboring grid cells, which means that the respective parameters of their unit cells are the same in both grid cells, at least at their contact surface. This avoids structural edges or fitting errors within the structure. The wall thickness within the structure is preferably changed. More preferably, in the case of cavities (e.g. channels or chambers) that are at least partially surrounded by preferably curved surfaces or walls, a surface (wall) can be offset or moved using a variable surface offset, so that the extent of the cavity within the structure is changed. This preferably takes place after the unit cell has been fitted into the grid cells, so that walls and channels, for example, are subsequently changed.
[0072] The invention will be explained in more detail below with reference to exemplary embodiments in the accompanying figures. In the various figures, identical components are provided with identical reference numerals. They show:
[0073] Figure 1 is a schematic, partially sectioned view of an embodiment of an apparatus for additive manufacturing with a control data generation device according to the invention,
[0074] Figure 2 shows a structuring according to the state of the art,
[0075] Figure 3 the creation of a structure using a lattice and a unit cell,
[0076] Figure 4 is a block diagram of an example of a method according to the invention,
[0077] Figure 5 shows the structuring of a component by subdivision in the form of a grid and filling with a unit cell,
[0078] Figure 6 possible transformations of a grid,
[0079] Figure 7 further possible transformations of a lattice,
[0080] Figure 8: Cutting out a structured grating region. The following exemplary embodiments are described with reference to a device 1 for the additive manufacturing of components in the form of a selective laser sintering or laser melting device. It should be explicitly noted once again that the invention is not limited to selective laser sintering or laser melting devices. The device will therefore be referred to below—without limiting its generality—as "manufacturing device" 1.
[0081] Such a manufacturing device 1 is shown schematically in Figure 1. The device has a process chamber 3 or a process space 3 with a chamber wall 4, in which the manufacturing process essentially takes place. Located within the process chamber 3 is an upwardly open container 5 with a container wall 6. The upper opening of the container 5 forms the current working plane 7. The area of this working plane 7 lying within the opening of the container 5 can be used to build the object 2 and is therefore referred to as the construction field 8.
[0082] The container 5 has a base plate 11 which is movable in a vertical direction V and is arranged on a carrier 10. This base plate 11 closes off the container 5 at the bottom and thus forms its base. The base plate 11 can be formed integrally with the carrier 10, but it can also be a plate formed separately from the carrier 10 and fastened to the carrier 10 or simply mounted thereon. Depending on the type of specific build material, for example the powder used, and the manufacturing process, a build platform 12 can be attached to the base plate 11 as a build base, on which the object 2 is built. In principle, however, the object 2 can also be built on the base plate 11 itself, which then forms the build base.
[0083] The basic construction of the object 2 occurs by first applying a layer of build material 13 to the build platform 12. Then, using a laser beam 22 as an energy beam, the build material 13 is selectively solidified at the points that are to form parts of the object 2 to be manufactured. Then, with the aid of the carrier 10, the base plate 11, thus the build platform 12, is lowered, and a new layer of build material 13 is applied and selectively solidified, etc. In Figure 1, the object 2 constructed in the container on the build platform 12 is shown below the work plane 7 in an intermediate state. It already has several solidified layers, surrounded by unsolidified build material 13.Various materials can be used as the building material 13, preferably powder, in particular metal powder, plastic powder, ceramic powder, sand, filled or mixed powders or also pasty materials and optionally a mixture of several materials.
[0084] Fresh build material 15 is located in a storage container 14 of the production device 1. With the aid of a coater 16 movable in a horizontal direction H, the build material can be applied in the form of a thin layer in the working plane 7 or within the build area 8.
[0085] Optionally, an additional radiant heater 17 is located in the process chamber 3. This can be used to heat the applied build material 13, so that the irradiation device used for selective solidification does not have to introduce too much energy. This means, for example, that with the help of the radiant heater 17, a certain amount of basic energy can be introduced into the build material 13, which is naturally still below the energy required for the build material 13 to melt or sinter. An infrared radiator or VCSEL radiator, for example, can be used as the radiant heater 17.
[0086] For selective solidification, the production device 1 has an irradiation device 20, or more specifically, an exposure device 20 with a laser 21. This laser 21 generates a laser beam 22, which is deflected by a deflection device 23 in order to traverse the exposure paths or tracks (hatch lines) provided according to the exposure strategy in the respective layer to be selectively solidified and to selectively introduce the energy. Furthermore, this laser beam 22 is appropriately focused onto the working plane 7 by a focusing device 24. The irradiation device 20 is preferably located outside the process chamber 3, and the laser beam 22 is guided into the process chamber 3 via a coupling window 25 mounted on the top side of the process chamber 3 in the chamber wall 4.
[0087] The irradiation device 20 can, for example, comprise not just one but several lasers. These can preferably be gas or solid-state lasers or any other type of laser, such as laser diodes, in particular VCSELs (Vertical Cavity Surface Emitting Lasers) or VECSELs (Vertical External Cavity Surface Emitting Lasers), or a row of these lasers. Very particularly preferably, within the scope of the invention, one or more unpolarized single-mode lasers, e.g., a 3 kW fiber laser with a wavelength of 1070 nm, can be used. A control device 30 comprising a control unit 29, which controls the components of the irradiation device 20, namely, in this case, the laser 21, the deflection device 23, and the focusing device 24, is used to control the units of the production device 1.
[0088] The control unit 29 also controls the radiant heater 17 by means of suitable heating control data HS, the coater 16 by means of coating control data ST and the movement of the carrier 10 by means of carrier control data TS and thus controls the layer thickness.
[0089] In order to optimize the production process, the control data PS are generated or modified by means of a control data generation device 34 in the manner according to the invention in such a way that the control of the device 1 takes place at least temporarily in a mode according to the invention.
[0090] The control data generation device 34 here comprises a data interface 35, which is designed to receive a component data set D and a structure data set. The component data set D comprises data on the three-dimensional shape of a component 2 to be manufactured and data on a three-dimensional structural region S of the component 2, which is intended to be provided with a structure T. The structure data set comprises data on the structure of a unit cell E of a periodic structure T. In addition, the data interface 35 is also designed to output the control data PS to the device 1 for the additive manufacturing of a component 2.
[0091] The control data generating device 34 further comprises a grid unit 36, a fitting unit 37 and a control data unit 38 for carrying out the method according to the invention.
[0092] The grid unit 36 is designed to specify a grid G of three-dimensional grid cells g in the structural region S, wherein the grid cells g are homeomorphic to the unit cell E, but preferably at least one grid cell g deviates from the external shape of the unit cell E.
[0093] The fitting unit 37 is designed to fit the unit cell E into each grid cell g to form a structure T. This occurs in such a way that the shape of the unit cell E corresponds to the shape of the respective grid cell g. Furthermore, the fitting unit 37 is designed to fill the grid cells g with a fitted unit cell E to form a structure T. The unit cell E is thus copied, adapted to the shape of a grid cell g, and inserted into this grid cell g.
[0094] The control data unit 38 is designed to create control data PS for the layer-by-layer construction of a component 2 whose structure area S is structured with the structure T.
[0095] The control data generation device 34 does not necessarily have to be part of the control device, although this is preferred. It can also be present externally. For example, the control device 30 can be coupled, as shown here, via a bus 60 or another data connection to a terminal 40 with a display or the like. An operator can use this terminal 40 to control the control device 30 and thus the entire laser sintering device 1, e.g., by transmitting control data PS generated there by a control data generation device 34 (as indicated by dashed lines).
[0096] It should also be noted again at this point that the present invention is not limited to such a manufacturing device 1. It can be applied to other methods for the generative or additive production of a three-dimensional object by layer-by-layer application and selective solidification of a building material, wherein an energy beam is emitted onto the building material to be solidified. Accordingly, the irradiation device can be not only a laser, as described here, but any device could be used with which energy can be selectively applied to or into the building material as wave or particle radiation. For example, another light source, an electron beam, etc., could be used instead of a laser.
[0097] Even though only a single object 2 or component 2 is shown in Figure 1, it is possible and generally common practice to produce multiple objects in parallel in the process chamber 3 or container 5. For this purpose, the build material is scanned layer by layer by the energy beam 22 at locations that correspond to the cross-sections of the objects in the respective layer.
[0098] Figure 2 shows the structuring of an object with a gyroid structure according to the state of the art. A gyroid unit cell E (left), here in the form of a partially filled solid, is duplicated in the x, y, and z directions (arrow), intersected with an object, here a sphere (logical AND operation), and the right-hand geometry remains. The result, component 2, is a solid model made up of partially intersected gyroid unit cells E.
[0099] Figure 3 shows the basic construction of a structure T, which in this case is a gyroid structure T, using a lattice G, into whose lattice cells g the unit cell E (here, gyroid unit cell E) is fitted. First, a gyroid unit cell E is known (left), which is fitted into all lattice cells g of the lattice G (center). Fitting corresponds to fitting the gyroid unit cell E into the lattice cells g. The gyroid structure T is created from the fitted gyroid unit cells E.
[0100] Figure 4 shows a block diagram of an example of a method according to the invention for generating control data PS for the additive manufacturing of a component 2 in a manufacturing process in which, using a device 1 (see, for example, Figure 1), build-up material 13, preferably comprising a metal powder, is built up layer by layer in a build field 8 by selectively solidifying build-up material 13 by irradiating the build-up material 13 with at least one energy beam 22.
[0101] In step I, a component data set D is provided. This includes data on the three-dimensional shape of a component 2 to be manufactured and data on a three-dimensional structural region S within the component 2, which is intended to be provided with a structure T, e.g., a gyroid structure T as shown in Figure 3.
[0102] In step II, a structural data set comprising at least data for the construction of a unit cell E of a periodic structure T is provided. This step can also occur before step I or simultaneously with it. The unit cell E can also already exist as a data set in a program. "Providing" then involves retrieving this data. The unit cell E here is, for example, a gyroid unit cell E based on the formula sin x cos y + sin y cos z + sin z cos x = 0. The depicted gyroid unit cell E has cubic symmetry, and the lattice cells g are also (initially) cubic.
[0103] In step III, a grid G consisting of three-dimensional grid cells g is specified in the structure region S, where the grid cells g are homeomorphic to the unit cell E. This means that the unit cell can be fitted into any grid cell by distorting, twisting or bending. A grid cell g can deviate from the external shape of the unit cell E. In this case, adjacent grid cells g share vertices and have identical contact surfaces. In step IV, the unit cell E is fitted into each grid cell g to form a structure T, so that the shape of the fitted unit cell E corresponds to the shape of the respective grid cell g. The unit cell E is copied and morphed into the shape of the respective grid cells g. The grid cell g is therefore filled with an adapted copy of the unit cell E.
[0104] In step 5, control data PS for the layer-by-layer construction of a component 2 whose structural area S is structured with the structure T are then generated according to known methods, and these control data PS are output to a device 1 for the additive manufacturing of a component 2.
[0105] Figure 5 shows the structuring of a component 2 by subdividing it into a lattice G and filling it with the unit cell E. The component 2, in the form of a ring, is to be completely structured with a gyroid structure T. The structural area S therefore corresponds to the complete component 2. A lattice G is now created which subdivides the structural area S. This can be done by subdividing the volume of the structural area S or by fitting an elongated or already ring-shaped lattice into the structural area S. In the middle of the lattice G there is a cube-shaped gyroid unit cell E which is now fitted into the lattice cells g. The fitting can be done by compressing and bending the unit cell E. Basically the unit cell E only needs to be deformed once and then copied several times because the lattice cells g are all the same here. If all lattice cells g are identical with the fitted unit cell E (ortheir copies) is filled, then a component 2 with the structure T shown on the right is created.
[0106] Figure 6 shows possible transformations of a grid G that can be used to fit a structural area S. An example of the grid G is shown at the top, and a component 2 is shown below, which is formed entirely from a structural area S whose size corresponds to the grid G. From left to right, the following cases are shown:
[0107] On the far left, a normal lattice G with identical lattice cells g is shown. The resulting structure T is regular. Next to it is a lattice G that is only one lattice cell high but distorted in height. The resulting structure T consists of regularly arranged and correspondingly distorted gyroid unit cells E.
[0108] Next comes a grid G whose grid cells g are compressed to the right. The resulting structure T consists of correspondingly distorted gyroid unit cells E.
[0109] On the right is a lattice G whose lattice cells g are compressed to the right and upward. The resulting structure T consists of correspondingly distorted gyroid unit cells E.
[0110] Figure 7, following Figure 6, shows further possible transformations of the grid G. For better understanding, the Euclidean coordinates x, y, and z are introduced here, where x denotes the length, y the width, and z the height. From left to right, the following cases are shown:
[0111] In the left lattice G, the upper plane of the lattice G is tilted around the x-axis. Next to it is a lattice G that is twisted along its height. Next is a lattice G that is increasingly stretched in the xy direction with increasing height. On the right is a lattice G that is stretched in the z-direction. The resulting structures T each consist of correspondingly distorted gyroid unit cells E.
[0112] Figure 8 shows a section of a structured grid region. The structured region S is a cuboid with a square base located in the center of the grid G. The grid is stretched in the xy direction with increasing height (as in the third representation in Figure 7) and additionally stretched in the z direction with increasing height, so that at the bottom there are grid cells with very small gyroid unit cells E, which become increasingly larger towards the top.
[0113] In the middle image, all grid cells g are collapsed with fitted gyroid unit cells E. The resulting structure T is now cut to the structure area S using a logical AND function, resulting in a structured component 2 on the right.
[0114] Finally, it should be noted once again that the devices described in detail above are merely exemplary embodiments that can be modified in a variety of ways by those skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not exclude the possibility that the respective features may be present in multiple instances. Likewise, the term "unit" does not exclude the possibility that it consists of several interacting subcomponents, which may also be spatially distributed. The phrase "a number" is to be understood as "at least one."
[0115] List of reference symbols
[0116] 1 device for additive manufacturing / laser sintering device
[0117] 2 Component / Object
[0118] 3 Process room / process chamber
[0119] 4 chamber wall
[0120] 5 containers
[0121] 6 Container wall
[0122] 7 Working level
[0123] 8 Construction site
[0124] 10 carriers
[0125] 11 Base plate
[0126] 12 Construction platform
[0127] 13 Construction material (in container 5)
[0128] 14 storage containers
[0129] 15 assembly material (in storage container 14)
[0130] 16 coaters
[0131] 17 Radiant heating
[0132] 20 Irradiation device / exposure device
[0133] 21 lasers
[0134] 22 Laser beam / energy beam
[0135] 23 Deflection device / scanner
[0136] 24 Focusing device
[0137] 25 coupling windows
[0138] 29 Control unit
[0139] 30 Control device
[0140] 31 Irradiation control interface
[0141] 34 Control data generating device
[0142] 35 Data interface
[0143] 36 grid unit
[0144] 37 Fitting unit
[0145] 38 Control data unit
[0146] 40 Terminal
[0147] 60 buses
[0148] D Component data set E Unit cell
[0149] G Grid g Grid cell
[0150] H horizontal direction HS heating control data
[0151] PS process control data
[0152] S structural area
[0153] ST coating control data
[0154] T Structure TS Carrier Control Data
[0155] V vertical direction
Claims
Patent claims 1. Method for generating control data (PS) for the additive manufacturing of a component (2) in a manufacturing process in which, with a device (1) in a construction field (8), building material (13), preferably comprising a metal powder, is built up layer by layer by selectively solidifying building material (13) by irradiating the building material (13) with at least one energy beam (22), the method comprising the steps: - Providing a component data set (D) comprising data for three-dimensional Shape of a component (2) and data on a three-dimensional structural area (S) of the component (2) which is intended to be provided with a structure (T), - Providing a structure data set comprising at least data on the structure of a unit cell (E) of a periodic structure (T), - Predetermining a grid (G) of three-dimensional grid cells (g) in the structural area (S), whereby the unit cell (E) can be spatially arranged in the grid cells (g), - fitting the unit cell (E) into each grid cell (g) so that the shape of the unit cell (E) corresponds to the shape of the respective grid cell (g), and filling the grid cells (g) with a fitted unit cell (E) to form a structure (T), - Creating control data (PS) for the layer-by-layer construction of a component (2) whose structural area (S) is structured with the structure (T), - Outputting the control data (PS) to a device (1) for the additive manufacturing of a component (2).
2. The method according to claim 1, wherein the structure data set comprises data on a unit cell (E), preferably based on the formula sin x cos y + sin y cos z + sin z cos x = 0.
3. Method according to one of the preceding claims, wherein after forming the structure (T) the structure region (S) is changed together with the structure (T), preferably wherein the grid cells (g) of the grid (G) are deformed and / or their size is changed.
4. Method according to one of the preceding claims, wherein the symmetry of unit cell (E) and the lattice cells (g) is cubic, tetragonal, rhombic or orthorhombic, preferably wherein the unit cell (E) is cubic and lattice cells (g) are cubic, or distortions of a cubic shape.
5. Method according to one of the preceding claims, wherein in the course of fitting the unit cell (E) into a grid cell (g), the latter is deformed such that it corresponds to the shape of the grid cell (g), wherein preferably the position of corners and the orientation and / or length of edges of the unit cell (E) are changed and / or a side surface and / or an edge is curved, wherein the entire volume of the unit cell (E) is distorted accordingly, preferably wherein the deformation corresponds to a transformation with which the corresponding grid cell (g) has been transformed.
6. Method according to one of the preceding claims, wherein the grid cells (g), in particular after a transformation of the grid (G) or after the subdivision of a structural area (S), in at least a partial area of the grid (G) - are arranged regularly, and / or - have an identical size, or have different sizes, preferably with the size decreasing in at least one spatial direction, and / or - are longer in at least one spatial direction than in another spatial direction, - are increasingly twisted around at least one spatial axis along this axis, - are increasingly distorted with respect to at least one spatial axis along this in at least one other spatial axis.
7. Method according to one of the preceding claims, wherein at least a part of the grid (G) is predetermined by subdividing the structural area (S) and / or wherein a predetermined grid (G) is fitted by transformation into the shape of at least a part of the structural area (S), preferably wherein in the course of fitting the unit cell (E) into the grid cells (g) - when subdividing the structural area (S), the structural area (S) is first divided into a grid (G) and then the unit cell (E) is adapted to the grid cells (g), - a grid (G) is created, this is then adapted to the structure area (S) and then the unit cell (E) is adapted to the grid cells (g). - a grid (G) is created, then the unit cell (E) is fitted into the grid cells (g) and the grid (G) with the filled grid cells (g) is then fitted to the structural area (S).
8. Method according to one of the preceding claims, wherein a subdivision area comprising the structure area (S) is divided into a grid (G) comprising the predetermined grid (G), or a grid (G) is predetermined which extends at least over the structural area (S), the unit cell (E) is fitted into each grid cell (g) of the grid (G) and then the filled grid cells (g) are separated within the structural area (S), in particular by means of a logical AND function between the structural area (S) and the grid (G).
9. Method according to one of the preceding claims, wherein in the course of fitting the unit cell (E) into a grid cell (g), in addition to the geometric shape, further parameters of the unit cell (E) are also changed, in particular its wall thickness and / or coefficients of a TPMF function which determines the unit cell (E), preferably wherein the change in the parameters depends on a spatial direction within the grid cell (g) and / or the change is continuous for adjacent grid cells (g).
10. Control data (PS) for controlling a device (1) for additive manufacturing, which have been created according to a method according to one of the preceding claims.
11. Manufacturing method for the additive manufacturing of a component (2), wherein in a construction field (8) build-up material (13), preferably comprising a metal powder, is built up layer by layer by selectively solidifying build-up material (13) by irradiating the build-up material (13) with at least one energy beam (22) according to the control data (PS) according to claim 10, wherein in order to create component layers of the component (2), the energy beam (22) is moved over the construction field (8) within defined areas according to these control data (PS).
12. Control data generation device (34) for generating control data (PS) according to claim 10 for a device (1) for additive manufacturing of a component (2) in a manufacturing process in which, in a construction field (8), building material (13), preferably comprising a metal powder, is built up layer by layer by selective solidification of building material (13) by irradiation of the building material (13) with at least one energy beam (22), the control data generation device (34) comprising: - a data interface (35) designed to receive a component data set (D) comprising data on the three-dimensional shape of a component (2) and data on a three-dimensional structural region (S) of the component (2) which is intended to be provided with a structure (T), and a structural data set comprising data on the structure of a unit cell (E) of a periodic structure (T), - a grid unit (36) designed to specify a grid (G) of three-dimensional grid cells (g) in the structural region (S), wherein the unit cell (E) can be spatially arranged in the grid cells (g), - a fitting unit (37) designed to fit the unit cell (E) into each grid cell (g) so that the shape of the unit cell (E) corresponds to the shape of the respective grid cell (g), and filling the grid cells (g) with a fitted unit cell (E) to form a structure (T), - a control data unit (38) designed to create control data (PS) for the layer-by-layer construction of a component (2) whose structural area (S) is structured with the structure (T), - a data interface (35) designed to output the control data (PS) to a device (1) for the additive manufacturing of a component (2).
13. Control device (30) for a device (1) for the additive manufacturing of a component (2) in a manufacturing process in which, in a build field (8), build-up material (13), preferably comprising a metal powder, is built up layer by layer by selectively solidifying build-up material (13) by irradiating the build-up material (13) with at least one energy beam (22) by means of an irradiation device (20), wherein the control device (30) is designed to control the device (1) for the additive manufacturing of the component layers of the component (2) according to control data (PS) according to claim 10, wherein the control device (30) preferably comprises a control data generation device (34) according to claim 12.
14. Device (1) for the additive manufacturing of at least one component (2) in an additive manufacturing process with at least - a feed device for applying layers of building material (13) to a building area in a process space (3), - an irradiation device (20) for selectively solidifying building material (13) by irradiation with at least one energy beam (22), in particular between the application of two material layers, and - a control device (30) according to claim 13.
15. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to claims 1 to 9 and / or 11.