Method and device for generating control data for an additive manufacturing device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- EOS GMBH ELECTRO OPTICAL SYST
- Filing Date
- 2024-08-19
- Publication Date
- 2026-07-08
Smart Images
Figure EP2024073163_06032025_PF_FP_ABST
Abstract
Description
[0001] Method and device for generating control data for a device for additive manufacturing
[0002] The invention relates to a method for generating control data 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 field and, between the application of two layers of build-up material, a selective solidification of the build-up material occurs by irradiating the build-up material with at least one energy beam. Furthermore, the invention relates to corresponding control data and a corresponding control data generation device for generating control data, a control device for a device for additive manufacturing, and a corresponding device for the additive manufacturing of a component equipped with such a control device. Furthermore, the invention encompasses a manufacturing method for the additive manufacturing of a component.
[0003] Additive manufacturing processes are becoming increasingly relevant in the production of prototypes and, more recently, in series production. In general, "additive manufacturing processes" refers to manufacturing processes in which a finished product (hereinafter also referred to as a "component") is built up by depositing material (the "build material"), usually based on digital 3D design data. The build-up is usually, but not necessarily, layered. The term "3D printing" is often used as a synonym for additive manufacturing. The production of models, samples, and prototypes using additive manufacturing processes is often referred to as "rapid prototyping," the production of tools as "rapid tooling," and the flexible production of series components as "rapid manufacturing."As mentioned at the beginning, a key aspect is the selective solidification of the build material. In many manufacturing processes, this solidification can be achieved by irradiation with radiant energy, e.g., electromagnetic radiation, especially light and / or heat radiation, but possibly also with particle radiation such as electron beams. Examples of processes that use irradiation include "selective laser sintering" or "selective laser melting," or "powder bed-based laser beam melting" (also abbreviated to LPBF for "Laser Powder Bed Fusion").This involves repeatedly applying thin layers of a build-up material, usually in powder form, on top of one another. In each layer, the build-up material is selectively solidified in a "welding process" by spatially limited irradiation of the areas that are to become part of the component after production. This process involves partially or completely melting the powder grains of the build-up material using the energy locally introduced by the radiation at that point. After cooling, these powder grains are then solidified together to form a solid. The energy beam is usually guided over the build area along solidification paths, and the remelting or solidification of the material in the respective layer takes place in the form of "weld paths" or "weld beads," so that ultimately the component contains a multitude of such layers formed from weld paths.
[0004] During additive manufacturing using such a process, residual stresses are induced in components, which often lead to deformations during the process or when the component is subsequently removed from the build plate. These residual stresses arise from the fact that a new layer of material is melted onto a layer of material formed by previously melted and now solidified build material during production. During solidification or cooling, the newly applied layer shrinks, creating stresses in the lower layer. These stresses can lead to deformation of the component after the component is removed from the build plate.
[0005] To calculate such deformations in advance, the inherent strain method has been established in practice. It is assumed that, depending on the simulation accuracy, the deformation of the component is caused by a process-related inherent strain state when simulating hatches, layers, or blocks of the component. In a process where the simulation is aligned with experiments, this inherent strain state is calibrated. This strain state can be represented using a tensor e as follows:
[0006] The tensor entries represent the numerical value for the respective strain. e xx denotes the inherent strain in the scan direction, e yy perpendicular to the scan direction and e zz the inherent expansion in the direction of construction. Whereby, e xx > e yy, because the stress along a hardening path is greater than the stress perpendicular to it. The simplest formula for describing this is:
[0007] _ L x~ L xo _ L X ZX f c xx , , \ -) xo xo Where Lx is the actual length of the body under load in the x-direction and L x o the original length in this direction. Therefore AL X = £ xx L x o. If hardening paths occur in different directions, an internal stress or a resulting internal stress occurs over the entire component.
[0008] It is an object of the present invention to provide methods for generating control data or for additive manufacturing of a component as well as suitable devices therefor in order to be able to produce components with reduced deformation or reduced residual stress, preferably in a selective laser sintering process.
[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 control data generating device according to patent claim 11, a control device for a manufacturing device according to patent claim 12, a device for the additive manufacturing of components (also called “manufacturing device” for short) according to patent claim 13 and a manufacturing method according to patent claim 14.
[0010] In the method according to the invention for generating control data, control data is generated for a device for the additive manufacturing of a component in a manufacturing process. In this manufacturing process, build-up material is built up layer by layer in a build field, i.e. one after the other in several material application levels or material layers. The build-up material is preferably a metal powder. However, the invention is not limited to this, but can also be used with other, preferably powdered, build-up materials, such as plastics or ceramics or mixtures of the different materials. In this case, build-up material is solidified, preferably selectively, between the application of two material layers by irradiating the build-up material with at least one energy beam generated by an irradiation unit of the manufacturing device.As a rule, not only the build-up material in the top, freshly applied material layer is captured and melted or remelted by the energy beam, but the energy beam usually goes a little deeper into the material bed and also reaches the underlying, already remelted material from previously applied material layers.
[0011] The control data is created in such a way that the production device is activated so that the energy beam or an impact surface of the energy beam, as mentioned at the beginning, is moved across the build field along a number of solidification paths. "Moving" can be understood to mean the usual deflection of the energy beam, e.g. by galvanometer mirrors, but also a movement of the entire beam emission unit, e.g. in the form of a diode bank, in particular a laser diode bank, or by moving beam shaping of the irradiation unit. The energy introduced with the energy beam melts build material along these solidification paths in an area in the impact surface and around the impact surface of the energy beam on the build field, since the total energy input is high enough in each case.
[0012] To fill surfaces with a fill pattern of hardening paths in the form of hatching, the energy beam is guided across the cross-section of the component in the respective layer according to the fill pattern. Since the hardening paths are only created during production, “vectors” are defined in advance along which the energy beam is to be moved. The orientation of a hatch is usually specified using “hatch vectors” (from the English “hatching”). According to these hatch vectors, the energy beam is then traced along short, adjacent hardening paths during subsequent production, e.g. so-called hatches, which usually run at an angle to an irradiation strip or within an irradiation field.The uniform filling of a partial structure of the component layer (i.e. in a partial area of the component layer) is referred to below as a “fill pattern” and is usually a hatching that is specified by the “hatch vectors”.
[0013] A hatch vector can be represented by coordinates, especially on a two-dimensional surface. However, it can also be specified solely by its angle relative to a general coordinate system or relative to a substructure. The length of the hatch vector is essentially not that important and does not necessarily have to be specified for its definition, since it can also be specified, for example, by the dimensions of a substructure. Essentially, the only important thing is that the hatch vector is designed in such a way that it defines the orientation of the fill pattern (hatching) in the substructure to which it is assigned.
[0014] Please note that the fill pattern is not filled with hatch vectors. Essentially, a single hatch vector per fill pattern is sufficient to specify the direction in which the solidification paths should run. The length of the solidification paths and their arrangement can be determined in a later step during the generation of specific control data. In short, a fill pattern of a substructure comprises hatch lines ("hatch lines") whose orientation is specified by the corresponding hatch vector (assigned to the substructure). The fill pattern preferably fills the substructure completely.
[0015] The method according to the invention comprises the following steps:
[0016] - Obtaining or generating layer information that determines the layer structures of the component,
[0017] - subdividing at least one layer structure into a plurality of substructures, which together form a number, in particular a plurality, of ring shapes which enclose a (common) point, whereby adjacent substructures touch each other so that they form a closed surface,
[0018] - individually assigning a hatch vector to each substructure, whereby the hatch vectors are selected so that they lie at the level of the layer structure and the orientations of hatch vectors of adjacent substructures differ,
[0019] - Generating control data such that the additive manufacturing device can use this control data to generate a segment fill pattern with hatching from essentially parallel hatch lines (within the usual tolerances) along the respective hatch vectors.
[0020] In the state of the art, it is sufficiently known what layer information is and how it can be obtained or generated. As a rule, components are initially available as CAD files which contain the geometric structure of a component. Using so-called "slicers", these components can be divided into virtual layers. These virtual layers are then available as layer information. This layer information comprises a number of layer structures of the component. These layer structures are geometric surfaces which correspond to the respective component layer. A compact component usually has a single layer structure (for example, a square in a cube); complex components can sometimes have several layer structures (for example, a component in the form of a compact model of the Atomium in Brussels has several circles and ellipses of different sizes).In short, the process then has access to a number of layer structures that represent the respective geometric shape of the component layer. These layer structures are available as geometric information. In the subsequent step, at least one of these layer structures is divided into a number of substructures. These substructures are surfaces within the respective layer structure. The substructures are arranged in such a way that they form ring shapes (possibly in groups).
[0021] The term “ring shape” generally refers to a square ring or a round ring, and in particular to a circular ring. A ring is essentially the area between two polygons or ellipses, with the outer shape completely surrounding the inner one. One could also say that the inner line of a ring shape is always concave and the outer line is always convex. However, this does not necessarily mean that this applies to all substructures, since, for example, a hexagonal ring shape can also be composed of trapezoidal substructures. A preferred ring is a circular ring, i.e. the area between two concentric circles, or a correspondingly polygonal ring in the form of the area between two concentric polygons of the same shape (and in particular regular) but different size. Ring shapes enclose a common point and are preferably arranged concentrically.
[0022] The ring shapes preferably form an inner and / or outer contour of the cross-section of the component or a contour within the cross-section of the component. This contour is preferably designed such that at least two points on the contour can be defined, with a straight line (a secant of the contour) being defined through these two points that does not intersect other points of the contour.
[0023] A (round or square) ring shape preferably has at least five corners, preferably at least six corners, or an elliptical shape, in particular that of a circle. It is not absolutely necessary for the ring structure to be closed, although a closed ring structure represents a preferred embodiment. With such a square ring structure, it is preferred that a side edge of a partial structure (actually of two partial structures, since two partial structures collide at this side edge) runs through a corner of the ring structure, preferably with each corner of the ring structure being divided by a side edge.
[0024] Preferably, each substructure is shaped such that one of its edges (referred to as a "shell edge") lies on the inner edge of the ring shape and one of its opposite edges (also a "shell edge") lies on the outer edge of the ring shape. Conversely, edges (shell edges) of each substructure that are not directly adjacent to one another correspond to part of the inner or outer edges of the resulting ring shape. Of course, there can be several groups of ring shapes R, each enclosing different common points. For ease of differentiation, the edges are referred to here as "shell edges" because they delimit a shell surface of a general cylinder or prism.
[0025] The substructures preferably have radial side edges (the edges with which substructures of a ring structure abut one another, i.e., not shell edges). A radial side edge preferably lies on a straight line passing through a point inside the ring structure, in particular through its center, e.g., on the radius of a circle.
[0026] Preferably, at least one side edge of a partial structure does not form a right angle with the shell edges adjacent to this side edge.
[0027] The surface formed from the ring shapes has no holes, except for the area around the common point or areas at the edges of the substructure. At least there are no holes between adjacent substructures, which is what is meant by the feature that adjacent substructures touch each other, so that they form a closed surface. By “closed” we mean that there should be no holes in the area of the touching edges between adjacent substructures. Since this also applies to the lateral surfaces of the ring shapes, there are also no holes between adjacent ring shapes. Two directly adjacent ring shapes therefore share a common edge (the inner edge of one is the outer edge of the other). For example, the substructures can form nested, particularly concentric, circular rings that each abut each other via a common circular arc.However, it is advantageous if the substructures are in the shape of circular ring segments and, when combined, form these circular rings. It should be noted that there may be an area inside the ring shapes that does not necessarily have to be considered a ring shape. This area can also be considered a substructure, but it can have a unique fill pattern. This will be described in more detail below.
[0028] Each substructure is then assigned a hatch vector, i.e. the hatching, in particular the angle of the hatch lines (hatch angle) to the substructure is defined. Each substructure is assigned an individual hatch vector, and the hatch vectors are selected so that they lie on the level of the layer structure and the orientations of hatch vectors of adjacent substructures differ relative to a common ("globally") coordinate system. The common coordinate system can be a machine coordinate system, for example. It should be noted that in the case of substructures of the same shape that are rotated relative to one another, the hatch vectors can certainly be identically aligned relative to the substructures. Due to the rotation of the substructures relative to one another, the (global) orientations of the hatch vectors are still different.
[0029] Finally, the control data is generated based on these hatch vectors. The general procedure is well known in the art. However, the special feature is that the hatch vectors were created in the above manner, resulting in special filling patterns that reduce residual stress in the component during production, resulting in minimal or no deformation of the component.
[0030] The method results in the control data according to the invention for controlling a device for additive manufacturing.
[0031] This control data includes, for example, data that specifies the locations within the process space or build area where material is to be solidified, i.e., which parts will later become part of the component or any support structures or the like, and which areas will not. Accordingly, the control data can preferably be exposure control data, such as scan data that defines or specifies the movement of the energy beam on the surface, control data for adjusting the energy level or laser intensity, control data regarding the "shape" of the beam or the beam profile, and / or the focus or extension of the beam perpendicular to the beam direction.Furthermore, these control data can also include other control information, such as coating control data that specifies the thickness of a current layer, information for controlling pre- or post-heating with other energy input means or for injecting protective gas.
[0032] For the sake of completeness, it should be mentioned again at this point that the energy beam can be either particle radiation or electromagnetic radiation, such as light or, preferably, laser radiation.
[0033] It should also be noted that multiple energy beams can be deployed in a coordinated manner, either in parallel at different locations on the component's cross-section (e.g., to increase build speed) or combined at a single location, as will be explained later using an example. Accordingly, the control data must be designed to allow for the coordinated control of multiple energy beams.
[0034] A control data generation device according to the invention for generating control data for a device for additive manufacturing of a component in a manufacturing process in which 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 an energy beam. Selective solidification of the build material occurs, preferably between the application of two layers of build material, by irradiating the build material with at least one energy beam from an irradiation device. The device is designed to create control data with which the additive manufacturing device can be controlled using the control data so that the energy beam is moved across the build field along a number of solidification paths. It comprises the following components:
[0035] - a data interface designed to receive layer information comprising layer structures of the component, or a cutting unit (slicer) designed to generate layer information comprising layer structures of the component, wherein surfaces of the layer structures are to be solidified with a predetermined filling pattern,
[0036] - a segmentation unit designed to divide at least one layer structure into a plurality of substructures, which together form a number, in particular a plurality, of ring shapes which enclose a (common) point, wherein adjacent substructures touch each other so that they form a closed surface,
[0037] - an assignment unit designed to assign an individual hatch vector to each substructure, wherein the hatch vectors are selected such that they lie at the level of the layer structure and the orientations of hatch vectors of adjacent substructures differ relative to a common coordinate system,
[0038] - a control data generation unit designed to generate control data such that the device for additive manufacturing can use this control data to generate a filling pattern with hatching from hatch lines that are essentially parallel to one another along the respective hatch vectors.
[0039] The functions of the individual units have already been described in the context of the process. The control data generation device can, for example, be part of a control device of a manufacturing device for the additive manufacturing of components. However, it can also be implemented independently on another computer to then transfer the data to the control device.
[0040] The control device according to the invention for a device for the additive manufacturing of a component in a manufacturing process in which build material, preferably comprising a metal powder, is built up layer by layer in a build area by selectively solidifying the build material by irradiating the build material with an energy beam, is designed to control the device according to control data according to the invention. It is preferred that the control device comprises a control data generation device according to the invention.
[0041] A device according to the invention (manufacturing device) for the additive manufacturing of components in an additive manufacturing process comprises, in addition to the usual components, such as a feed device for introducing material layers of build material in a build field into a process space, and an irradiation device for selectively solidifying the build material by irradiation by means of an energy beam, at least one control device according to the invention.
[0042] The device according to the invention can, in particular, comprise a plurality of irradiation devices that are controlled in a coordinated manner using the control data. The energy beam can also consist of a plurality of overlapping energy beams.
[0043] The device according to the invention for the additive manufacturing of components shares the advantages of the method according to the invention for the additive manufacturing of a component.
[0044] In the 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 an energy beam. Preferably, between the application of two layers of build material, selective solidification of the build material occurs by irradiating the build material with at least one energy beam. This occurs according to the control data according to the invention, wherein, to create layer structures of the component, the energy beam is moved across the build field within defined regions of the layer structure according to these control data (i.e., to generate a plurality of mutually parallel solidification paths).
[0045] The control data generation device 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, have 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 to operate in the manner according to the invention by means of a software or firmware update.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.
[0046] 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.
[0047] According to a preferred method, the substructures are polygons or circular ring sectors. Polygons would form angular ring shapes, and circular ring sectors would form a circular ring or at least an elliptical ring. Preferably, the substructures forming a ring shape each have an identical shape. These ring shapes are therefore formed from N>1 substructures, preferably from N>2, depending on the size of the ring shape, with N>3 being particularly preferred. This can apply to some of the nested ring shapes or to all of them. It is preferred that the ring shapes are arranged concentrically around the common point. However, they do not have to completely fill the inner area, as this can be filled in another way with a fill pattern, e.g. a spiral pattern or a separate hatching.
[0048] Preferably, the substructures of adjacent, i.e., adjacent, ring shapes are arranged offset from one another. This means that the side edges (the lateral edges with which substructures of a ring shape abut one another) within the adjacent ring shapes do not lie on a common straight line, or that the inner and outer edges of the substructures of a ring shape are offset from one another (radially shifted), while the lateral edges lie on a common straight line (but do not completely overlap). The arrangement of the substructures preferably corresponds to the arrangement pattern of an arc-shaped series arrangement, in particular a half-array arrangement. This has the advantage of achieving greater strength and a further reduction of the residual stress in the component.
[0049] In a preferred embodiment, the ring shapes are circular rings or elliptical rings or parts of a circular ring or elliptical ring, and the substructures are circular ring sectors or elliptical ring sectors, preferably with an opening angle of 60° or smaller, in particular of 45° or smaller, or even of 30° or smaller. Internal stresses are avoided all the better the smaller the subsegments are; however, the production speed decreases with size, so an optimal size should be found here. Smaller ring shapes could, for example, be divided into fewer subsegments than larger ring shapes, whereby it is preferred that one (in particular each) ring shape that surrounds another ring shape with T subsectors should be constructed from at least T+1 subsectors.According to a preferred method, the (possible) orientations of the hatch vectors of the substructures are specified by specifying limits for the orientation of the hatch vector of a (preferably quadrangular) substructure through the diagonals through corner points of the (in particular quadrangular) substructure, which divide the respective substructure into four angular sectors, whereby the intersection point of the diagonals is determined, and permissible angular ranges for the orientations of the hatch vector of this substructure are determined from the intersection point by the two radial angular sectors. These are the sectors in which the mantle edges, not the side edges, lie. Starting from the intersection point, a straight line in the direction of the hatch vector (at least in quadrangular substructures) may therefore only intersect the mantle edges and not any side edges.In the preferred case, where the substructures have exactly four corners, the two diagonals cross each other through opposite corners and intersect within the substructure. Since the hatch lines should not run along the ring shape, they should not run from the intersection of the diagonals toward the side edges, but rather toward the shell edges. The specific hatch vector for a substructure can then be selected from the possible orientations, especially with regard to neighboring substructures.
[0050] According to an alternative or supplementary preferred method, the orientations of the hatch vectors of the substructures are predetermined by determining the orientation of a plurality of hatch vectors by minimizing a cost function with a comparison with a predetermined reference length for a hatch vector (in particular as optimal) with variation of the size of the substructures and / or with variation of the orientation of the hatch vector.
[0051] In the cost function, the angles are preferably determined such that the component's resistance to mechanical forces is maximized, i.e., that the component's deformation upon application of a force is minimized or at least distributed as evenly as possible. A force can arise during the construction process itself (typically, warpage) or can be a force that arises during the application of the component (e.g., a bending force or a torsional force). In principle, the angle between exposure vectors and the longitudinal direction of the deformation resulting from the application of a force should be as large as possible. The "cost function" is therefore preferably an "optimization function" to maximize the component's mechanical resistance.In general, it is preferred that the hatch angles of the hatch vectors of at least two, preferably all, substructures in a ring shape are essentially the same relative to the corresponding side edges of the respective substructures. For identical substructures within the ring shape, this results in each of these substructures having the same hatch angle internally (but not in a common coordinate system), which rotates with the orientation of the substructure. Locally (within the substructures), the hatch angles can therefore be the same, but globally they differ.
[0052] According to a preferred method, hatch vectors of at least two adjacent substructures of adjacent ring shapes are mirrored and / or rotated substantially 90° relative to each other. This mirroring or rotation occurs relative to a common coordinate system.
[0053] In general, the (local) hatch angle should preferably vary from ring shape to ring shape. Furthermore, the substructures should exhibit a plurality of different hatch angles, viewed from a common coordinate system (i.e., globally). In this regard, it is preferable that fewer than 20% of all substructures have the same (globally) hatch angle, and particularly preferably fewer than 10% or even fewer than 1%. This is advantageous because material shrinks in the hatching direction, and thus residual stresses can arise if many solidification paths have the same orientation. It should be noted that identical hatch angles can often be present within the substructures (i.e., locally), at least if the substructures are correspondingly rotated relative to one another.
[0054] According to a preferred method, side edges of the partial structures of a ring shape are inclined relative to the radial direction present there by an angle A of less than 90°, preferably less than 60°. The radial direction is the direction of a straight line passing through the common point and the nearest point of the side edge. In contrast to ring segments with "radial side edges" (i.e. side edges in the radial direction), the side edges of this embodiment are inclined to the radial side edges by an angle A. It is preferred that the side edges of all partial structures of a ring shape are inclined by the same angle A to the respective radial direction present there. This shape can be vividly imagined by transferring the differences between a parallelogram and a rectangle to a ring segment.Preferably, the hatch vector of a substructure with side edges inclined by the angle A has an inclination that lies between the inclinations of the two side edges of the substructure and, in particular, corresponds exactly to half the angle between the two side edges. The hatch angle thus corresponds to an angle bisecting the two opposite side edges.
[0055] According to a preferred method, adjacent hatch lines of neighboring substructures are considered to be a single path to be consolidated together. Alternatively, or elsewhere, hatch lines are consolidated according to a scheme in which no more than two adjacent hatch lines are consolidated consecutively in a substructure. This is therefore taken into account when creating the control data. This is particularly interesting in the case where hatch lines of neighboring substructures abut one another.
[0056] According to a preferred method, structures with an area and / or extent below a predetermined limit are provided with an alternative fill pattern that differs from the fill pattern. It is preferred that an area in the center of the ring shapes is provided with an alternative fill pattern consisting of concentric circles or a spiral shape. Alternatively or additionally, it is preferred that areas outside the ring shapes are designed in such a way that remaining areas of the layer structure are divided into fill areas and hatch vectors are assigned to these fill areas. This is particularly advantageous for the center of the ring shapes and corners of the layer structure. Above a certain size of a partial structure, hatching is no longer optimal as a fill pattern, particularly with regard to heat management. There are also areas of a layer structure that are not suitable for inclusion in a ring shape (e.g. corners).To ensure that the entire surface of the layered structure can be filled with patterns, these substructures can be provided with an individual fill pattern as described above. In practice, a condition for generating the control data could be that if the average hatch length of a substructure falls below the value X, an alternative strategy for forming the fill pattern is selected. The limit value X could depend on the material used, the remelting process applied, or the effectiveness of control tools that influence the changed heat balance (e.g., time homogenization or power homogenization).According to a preferred method, the control data are designed such that after filling a substructure with a fill pattern, and before filling a substructure adjacent to this substructure with a fill pattern, another (non-adjacent) substructure is first filled with a fill pattern. For example, every second substructure is solidified first, since shrinkage always occurs in the cooled areas. Hard material is then melted. The advantage lies in a further reduction of the residual stress. This process can also be accompanied by an intermediate coating, i.e. first each odd-numbered substructure is solidified, then new build material is applied and then the even-numbered substructures are solidified.
[0057] According to a preferred method, touching substructures of superimposed layer structures are arranged such that their abutting edges are each offset. This has the advantage of improved component stability. It is preferred that the hatch vectors of superimposed substructures differ with regard to their orientation in the plane of the layer structures (i.e., globally). Furthermore, it is preferred that the hatch vector of an upper substructure lying on two or more lower substructures is substantially orthogonal to the resulting vector of the hatch vectors of the substructures below. This additionally reduces residual stresses. It should be noted that this embodiment refers to the relationship between hatch vectors of superimposed component layers.
[0058] 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:
[0059] 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,
[0060] Figure 2 shows a layer structure with substructures which together form a plurality of ring shapes,
[0061] Figure 3 Partial structures with radially arranged side edges, which form two ring shapes,
[0062] Figure 4 partial structures with sloping side edges, which form two half ring shapes, Figure 5 a partial structure which is divided into areas by diagonals,
[0063] Figure 6 shows a partial structure with a Hatch vector that runs obliquely to a diagonal,
[0064] Figure 7 shows a partial structure with slanted side edges and a hatch vector,
[0065] Figure 8 shows a preferred hatching in substructures with sloping side edges,
[0066] Figure 9 shows a preferred hardening strategy,
[0067] Figure 10 is a block diagram of a preferred embodiment of a method according to the invention.
[0068] 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 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] 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, one or more unpolarized single-mode lasers, e.g., a 3 kW fiber laser with a wavelength of 1070 nm, can be used within the scope of the invention.
[0076] To control the units of the manufacturing device 1, a control device 30 comprising a control unit 29 is used, which controls the components of the irradiation device 20, namely here the laser 21, the deflection device 23 and the focusing device 24.
[0077] 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.
[0078] 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.
[0079] The control data generation device 34 here comprises a data interface 35, which is designed to receive layer information S1 comprising layer structures S of the component 2. However, it can also comprise a separate cutting unit for generating layer information S1 comprising layer structures S of the component 2. It is important that the subsequent units can work with the layer structures S defined in the layer information S1. The layer structures S can only be present as special layer information S1 (e.g., regarding the position and shape of the layer structures S). The segmentation unit 36 is designed to subdivide at least one layer structure S into a plurality of substructures T, which form a plurality of ring shapes R (enclosing a common point), with adjacent substructures T touching one another so that they form a closed surface. This is clearly shown in Figure 2.Of course, there can be several groups of ring shapes R, each enclosing a common point.
[0080] The assignment unit 37 is designed to assign an individual hatch vector HV to each substructure. The hatch vectors HV are selected such that they lie at the level of the layered structure S and the orientations of the hatch vectors HV of adjacent substructures T differ relative to a common coordinate system. This is illustrated, for example, in Figure 8, where the orientation of the hatch shown there corresponds to the hatch vectors.
[0081] The control data generation unit 38 is designed to generate control data PS, which are generated in such a way that the device 1 for additive manufacturing can generate a filling pattern F with hatchings of hatch lines that are essentially parallel to one another along the respective hatch vectors HV using these control data PS.
[0082] In this example, the optimized control data PS can be output to the device 1 for the additive manufacturing of a component 2 directly via the control data generation unit 38, as shown, or via the data interface 35.
[0083] 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).
[0084] 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.
[0085] 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.
[0086] Figure 2 shows a layered structure S with substructures T, which together form a plurality of ring shapes R. For better clarity, only three substructures T are provided with a reference symbol. The ring shapes R are formed entirely from corresponding substructures T. Hatched areas can be seen. These are substructures T that do not form ring shapes R, but are provided with their own separate fill pattern. The hatched circles in the middle of the ring shapes are too small to apply meaningful hatching and are filled, for example, with a spiral structure. The substructures T between the ring shapes R can be filled, for example, with hatching that is uniform, but is better done in different orientations (as shown).
[0087] Figure 3 shows substructures T with radially arranged side edges K, which form two nested, concentric ring shapes R. In this way, the ring shapes R of Figure 2 could be formed from substructures T. The substructures T of the two ring shapes R are arranged offset from one another. In the individual substructures T, hatch vectors HV are indicated by arrows, of which only one is provided with a reference symbol for the sake of clarity. Each arrow (hatch vector HV) is assigned to the substructure T in which it is located. Essentially, all arrows point in a different direction. This results in a component layer with very low residual stress during production. Figure 4 shows substructures T with inclined side edges K, which form two half ring shapes R. Essentially, this is an alternative to the radial arrangement of the side edges K according to Figure 3.
[0088] Figure 5 shows a substructure T divided into four regions by two diagonals D. The two hatched regions are "forbidden" regions in which a hatch vector HV originating from the intersection of the diagonals should not lie. A permitted hatch vector HV originating from the intersection of the diagonals is shown, pointing to a shell edge MK.
[0089] Figure 6 shows a partial structure T in the form of a circular ring segment with the opening angle α, with a hatch vector HV that runs at an angle β oblique to a diagonal D. Looking at Figure 5, this hatch vector HV also lies within the permissible range.
[0090] Figure 7 shows a partial structure T with oblique side edges K. Compared to Figure 6, the side edges K are tilted by the angle (p to the side edges K there. On the right side edge K, the course of the left side edge is sketched in dashed lines. The hatch vector HV drawn here runs along the angle bisector of these two lines.
[0091] Figure 8 shows a preferred hatching in substructures T with sloping side edges K, as sketched in Figure ?, for example. Three substructures T are shown, whereby further of these substructures T, attached to the upper side edges K, can form a complete ring shape R. The fill pattern F (a hatching) indicated by hatching is the same in each substructure T. By rotating the substructures T relative to one another, the fill patterns F are also rotated relative to one another. At the side edges K it can be seen that the hatch lines of adjacent substructures T almost collide and run in almost a continuous angular shape.
[0092] Figure 9 shows a preferred consolidation strategy. Here, the filling pattern F is designed so that the hatch lines of adjacent substructures T overlap and run in a continuous angular shape. The numbers at the bottom indicate the preferred consolidation sequences of the "hooks." According to the upper row of numbers, first one of the hooks is consolidated from left to right, then the next hook from right to left, and so on. According to the lower row of numbers, first one of the hooks is consolidated from left to right, followed by individual hatch lines of the other hooks.Figure 10 shows a block diagram of a preferred embodiment of a method according to the invention for generating control data PS for a device 1 for additive manufacturing of a component 2 in a manufacturing process in which, in a build field 8, build material 13, preferably comprising a metal powder, is built up layer by layer by selectively solidifying build material 13 by irradiating the build material 13 with an energy beam 22 (see Figure 1).
[0093] In step I, layer information S1 comprising a number of layer structures S of the component 2 is provided. These can be received externally or generated from object data.
[0094] In step II, at least one layer structure S is divided into a plurality of substructures T. These substructures T together form a plurality of ring shapes R, which enclose a common point, with adjacent substructures T touching each other so that they form a closed surface.
[0095] In step III, individual hatch vectors HV are assigned to each substructure T, wherein at least each substructure T of a ring shape R is assigned its own hatch vector, wherein the hatch vectors HV are selected such that they lie on the plane of the layer structure S and the orientations of hatch vectors HV of adjacent substructures T differ relative to a common coordinate system.
[0096] In step IV, control data PS are generated in such a way that the device 1 for additive manufacturing can use these control data PS to generate a filling pattern F with hatchings of essentially mutually parallel hatch lines along the respective hatch vectors HV.
[0097] This control data PS is then output.
[0098] 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."
[0099] List of reference symbols
[0100] 1 device for additive manufacturing / laser sintering device
[0101] 2 Component / Object
[0102] 3 Process room / process chamber
[0103] 4 chamber wall
[0104] 5 containers
[0105] 6 Container wall
[0106] 7 Working level
[0107] 8 Construction site
[0108] 10 carriers
[0109] 11 Base plate
[0110] 12 Construction platform
[0111] 13 Construction material (in container 5)
[0112] 14 storage containers
[0113] 15 assembly material (in storage container 14)
[0114] 16 coaters
[0115] 17 Radiant heating
[0116] 18 Sensor arrangement
[0117] 20 Irradiation device / exposure device
[0118] 21 lasers
[0119] 22 Laser beam / energy beam
[0120] 23 Deflection device / scanner
[0121] 24 Focusing device
[0122] 25 coupling windows
[0123] 29 Control unit
[0124] 30 Control device
[0125] 31 Irradiation control interface
[0126] 34 Control data generating device
[0127] 35 Data interface
[0128] 36 Segmentation unit
[0129] 37 Allocation unit
[0130] 38 Control data generation unit
[0131] 40 Terminal
[0132] 60 buses
[0133] D Diagonal F Segment fill pattern
[0134] H horizontal direction
[0135] HS heating control data
[0136] HV Hatch Vector K Side Edge
[0137] KM jacket edge
[0138] PS process control data
[0139] R ring shape
[0140] S Layer structure Sl Layer information
[0141] ST coating control data
[0142] T substructure
[0143] TS carrier tax data
[0144] V vertical direction a angle ß angle cp angle
Claims
Patent claims 1. Method for generating control data (PS) for a device (1) for the 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 selectively solidifying building material (13) by irradiating the building material (13) with an energy beam (22), the method comprising the steps: - Obtaining or generating layer information (Sl) comprising a number of layer structures (S) of the component (2), - subdividing at least one layer structure (S) into a plurality of substructures (T) which together form a number of ring shapes (R) which enclose a point, wherein adjacent substructures (T) touch each other so that they form a closed surface, - individually assigning a hatch vector (HV) to each substructure, whereby the hatch vectors (HV) are selected such that they lie on the level of the layer structure (S) and the orientations of hatch vectors (HV) of adjacent substructures (T) differ relative to a common coordinate system, - generating control data (PS) such that the device (1) for additive manufacturing can use these control data (PS) to generate a filling pattern (F) with hatchings from hatch lines that are essentially parallel to one another along the respective hatch vectors (HV).
2. Method according to claim 1, wherein the partial structures (T) are polygons or circular ring sectors, wherein preferably the partial structures (T) forming a ring shape (R) have an identical shape, and preferably wherein the ring shapes (R) are arranged concentrically around the common point, wherein the partial structures (T) of adjacent ring shapes (R) are particularly preferably arranged offset from one another.
3. Method according to claim 1 or 2, wherein the orientations of the Hatch vectors (HV) of the partial structures (T) are predetermined in that - limits for the orientation of the hatch vector (HV) of a substructure (T) are specified by diagonals through corner points of the substructure (T), which divide the respective substructure (T) into four angular sectors, whereby the intersection point of the diagonals (D) is determined, and permissible angular ranges for the orientations of the hatch vector (HV) of this substructure (T) are determined from the intersection point by the two radial angular sectors, and / or - the orientation of a plurality of hatch vectors (HV) is determined by minimizing a cost function with a comparison with a predetermined reference length for a predetermined hatch vector (HV) with variation of the size of the partial structures (T) and / or with variation of the orientation of the hatch vector (HV), preferably wherein the angles of the hatch vectors (HV) of at least two, preferably all, partial structures (T) in a ring shape (R) relative to mutually corresponding side edges (K) of the respective partial structures (T) are substantially equal.
4. Method according to one of the preceding claims, wherein hatch vectors (HV) of at least two adjacent partial structures (T) of adjacent ring shapes (R) are mirrored to each other and / or rotated substantially by 90° to each other.
5. Method according to one of the preceding claims, wherein side edges (K) of the partial structures (T) of a ring shape (R) are inclined relative to the radial direction present there by an angle A of less than 90°, preferably wherein the side edges (K) of all partial structures (T) of a ring shape (R) are inclined by the same angle A to the respective radial direction present there, preferably wherein the hatch vector (HV) of a partial structure (T) with side edges (K) inclined by the angle A has an inclination which lies between the inclinations of the two side edges (K) of the partial structure (T) and in particular corresponds exactly to half the angle of the two side edges (K) to one another.
6. Method according to one of the preceding claims, wherein abutting hatch lines of adjacent partial structures (T) are regarded as a web to be consolidated together and / or are consolidated according to a scheme in which no more than two adjacent hatch lines are consolidated one after the other in a partial structure (T).
7. Method according to one of the preceding claims, wherein for structures with an area and / or an extension below a predetermined limit value, an alternative filling pattern different from the filling pattern (F) is provided, preferably wherein in the center of the ring shapes (R) an area is provided with an alternative filling pattern of concentric circles or a spiral shape, and / or wherein outside the ring shapes (R) areas are designed in such a way that remaining areas of the Layer structure (S) is divided into fill areas (F) and hatch vectors (HV) are assigned to these fill areas (F).
8. Method according to one of the preceding claims, wherein the control data (PS) are designed such that after filling a partial structure (T) with a filling pattern (F), and before filling a partial structure (T) adjacent to this partial structure (T) with a filling pattern (F), first another partial structure (T) is filled with a filling pattern (F).
9. Method according to one of the preceding claims, wherein touching partial structures (T) of superimposed layer structures (S) are arranged such that their abutting edges are each arranged offset, preferably wherein the hatch vectors (HV) of superimposed partial structures (T) differ with regard to their orientation in the plane of the layer structures (S), preferably wherein the hatch vector (HV) of an upper partial structure (T) which lies on two or more lower partial structures (T) is substantially orthogonal to the resulting vector of the hatch vectors (HV) of the underlying partial structures (T).
10. Control data (PS) for controlling a device (1) for additive manufacturing, which have been generated according to a method according to one of the preceding claims.
11. 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 selectively solidifying building material (13) by irradiating the building material (13) with an energy beam (22), the control data generation device (34) comprising: - a data interface (35) designed to receive layer information (S1) comprising layer structures (S) of the component (2), or a cutting unit designed to generate layer information (S1) comprising layer structures (S) of the component (2), wherein surfaces of the layer structures (S) are to be solidified with a predetermined filling pattern (F), - a segmentation unit (36) designed to divide at least one layer structure (S) into a plurality of substructures (T) which together form a number of ring shapes (R) which enclose a point, wherein adjacent substructures (T) touch each other so that they form a closed surface, - an assignment unit (37) designed to assign an individual hatch vector (HV) to each substructure, wherein the hatch vectors (HV) are selected such that they lie on the level of the layer structure (S) and the orientations of hatch vectors (HV) of adjacent substructures (T) differ relative to a common coordinate system, - a control data generation unit (38) designed to generate control data (PS) such that the device (1) for additive manufacturing can use these control data (PS) to generate a filling pattern (F) with hatchings from hatch lines that are essentially parallel to one another along the respective hatch vectors (HV).
12. 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 an energy beam (22), wherein the control device (30) is designed to control the device (1) for the additive manufacturing of the component layer of the component (2) according to control data according to claim 10, wherein the control device (30) preferably comprises a control data generation device (34) according to claim 11.
13. Device (1) for the additive manufacturing of at least one component (2) in an additive manufacturing process comprising at least - a feeding device for applying material layers of building material (13) in a construction field into a process space (3), - an irradiation device (20) for selectively solidifying the building material (13) by irradiation by means of an energy beam (22), and - a control device (30) according to claim 12.
14. Manufacturing method for the additive manufacturing of a component (2), wherein in a build field (8) build material (13), preferably comprising a metal powder, is built up layer by layer by selectively solidifying build material (13) by irradiating the build material (13) with an energy beam (22), wherein irradiation of the build material (13) with at least one energy beam (22) takes place according to the control data (PS) according to claim 10, wherein in order to create layer structures (S) of the component (2), the energy beam (22) is moved over the build field (8) within defined regions of the layer structure (S) according to the control data (PS).
15. Computer program product with a computer program which can be loaded directly into a memory device of a control data generation device (34) and / or a control device (30) of a device (1) for additively manufacturing a component layer of a component (2), with program sections in order to carry out all steps of the method according to one of claims 1 to 9 and / or a manufacturing method according to claim 14 when the computer program is executed in the control data generation device (34) and / or control device (30).