Method for preparing a process in additive manufacturing, and computer program product

Abstract

The invention relates to a method for preparing a process in the additive manufacturing of a component (10). The method has the steps of (i) importing a component geometry (CAD) into a CAD environment, (ii) inspecting the component geometry (CAD) for regions (10', 10'', 10'i, 10'o, 10''i, 10''o) which are to be provided with a different resolution quality during the manufacture process, and (iii) separating the component geometry into at least two component sub-geometries (10i, 10o) on the basis of the inspection, wherein in the manufacturing process, a first sub-geometry (10i) is constructed using a first layer thickness (d1), and a second sub-geometry (10o) which differs from the first sub- geometry (10i) is constructed using a second layer thickness (d2), said second layer thickness (d2) being smaller than the first layer thickness (d1), in particular half as large as the first layer thickness. The invention additionally relates to a corresponding additive manufacturing method and to a computer program product obtained using the method.

Description

[0001] Description

[0002] Method for process preparation in additive manufacturing and computer program product

[0003] The present invention relates, in particular, to a computer-implemented method for process preparation in the additive manufacturing of a component. The method relates to process-preparatory instructions, which, for example, together with CAM data ("computer-aided manufacturing"), form a control instruction for the additive manufacturing.

[0004] The component or its geometry is not subject to any real restrictions, but can preferably be intended for use in the hot gas path of a gas turbine. For example, the component concerns a component to be cooled with a thin-walled or delicate design. Alternatively or additionally, the component can be a component for use in the automotive or aerospace sectors.

[0005] Additive manufacturing processes (AM), colloquially also referred to as 3D printing, include, for example, selective laser melting (SLM) or laser sintering (SLS) as powder bed processes, or electron beam melting (EBM). "AM" has proven to be particularly advantageous for complex or delicately designed components, for example labyrinth-like structures, cooling structures and / or lightweight structures. In particular, additive manufacturing is advantageous due to a particularly short chain of process steps, since a manufacturing or production step of a component can largely be carried out on the basis of a corresponding CAD file and the selection of corresponding manufacturing parameters.

[0006] The production of, for example, turbine blade designs, heat exchangers or other components using the described powder bed-based processes (LPBF stands for "Laser Powder Bed Fusion") advantageously enables the implementation of new geometries or concepts that can reduce manufacturing costs or assembly and throughput times, optimize the manufacturing process and, for example, improve the thermo-mechanical design or durability of the components.

[0007] Components manufactured by conventional means, for example by casting, are clearly inferior to the additive manufacturing route, for example in terms of their freedom of design and also in terms of the required throughput time and the associated high costs as well as the manufacturing effort.

[0008] However, the powder bed process inherently creates high thermal stresses in the component structure. In particular, irradiation paths or vectors that are too short lead to severe overheating, which in turn causes the structure to warp. Severe warping during the build process easily leads to structural detachment, thermal deformation or geometric deviations outside of permissible tolerances. Accordingly, the selection, validation and implementation of customized process and irradiation parameters is usually complex. A particularly subtle and geometry-dependent definition of the process parameters often leads to long process and exposure times and build times of several days or even weeks.

[0009] An important limiting factor in powder bed-based additive manufacturing is therefore often the low productivity, since powder layers must usually be applied in the sub-100 μm range and must be irradiated and solidified very locally. Productivity can therefore be significantly increased, for example, by increasing the layer thickness. However, this is accompanied by a loss of resolution quality, particularly with regard to the resolution of small or delicate component structures, or weaker dimensional accuracy of the component. As a standard, a kind of optimum is often sought here, and the low productivity or the long build processes are largely accepted for a given specification of surface quality and dimensional tolerances.

[0010] It is therefore an object of the present invention to provide means by which a significant improvement in the productivity of powder bed-based additive processes can be achieved.

[0011] This problem is solved by the subject matter of the independent patent claims. Advantageous embodiments are the subject matter of the dependent patent claims.

[0012] One aspect of the present invention relates to a method, particularly a computer-implemented method, for process processing in additive component manufacturing.

[0013] The method includes importing a part geometry or CAD file into a CAM environment and / or a so-called build processor, a CAM system, a process controller and / or an additive manufacturing system.

[0014] CAM environment is to be understood broadly in the present case; i.e. the import of this file can, for example, also take place in advance outside of an image processor or a standard "pre-processing" environment. Thus, by means of the method according to the invention, no irradiation paths, for example, have to be defined. In order to utilize the advantages of the invention, it is merely advantageous to provide or include information on the orientation of the component design in the installation space of the corresponding system, a structure or surface requirement (resolution or structure quality) and / or, for example, a construction material with corresponding standard parameters for the import of the CAD file.

[0015] The method further comprises the, in particular algorithmic, examination of the imported component geometry for sub-areas of the component that are to be provided with a different resolution or structural quality (image quality) during the manufacturing process. This resolution quality can be specified, for example, by a component specification regarding surface quality or similar.

[0016] The method further comprises – based on the investigation – separating the component geometry, in particular the CAD data model for the actual subsequent 3D printing or manufacturing process, into at least two component sub-geometries. This separation can also involve a separation or subdivision of volume regions of the component, which can generally be processed with different process parameters in the subsequent additive manufacturing process. This subdivision advantageously makes it possible to select the parameters such that the productivity of the physical manufacturing process can be significantly increased by the process-preparatory method presented.

[0017] A first sub-geometry or a first component region is built up in the manufacturing process (subsequently) with a first layer thickness and a second sub-geometry, different from the first sub-geometry, with a second layer thickness, wherein the second layer thickness is smaller, in particular half as large as the first layer thickness. The layer thickness is known to be a dimension preset during CAM process preparation, according to which a raw material powder must be repeatedly distributed in a grid-like manner on the manufacturing surface in order to enable layer-by-layer irradiation and solidification of the component regions.

[0018] In one embodiment, an inner or first region of the component geometry (cf. first sub-geometry) is processed with the first layer thickness, and an outer region, second region or edge region of the component geometry (cf. second sub-geometry) is processed with the second layer thickness. In one embodiment, the first layer thickness for the inner region is approximately 80 pm and the second layer thickness for the outer region is approximately 40 pm. Without limitation, other layer thicknesses can alternatively be selected for both the inner and the outer region, for example in order to adapt and optimize the productivity of the process for each of the sub-geometries.

[0019] In one embodiment, the examination of the component geometry in areas with different resolution levels includes the identification of different component sections or component subcomponents, with each component section suggesting the application of different (specific) process parameters in the manufacturing process or requiring them in terms of resolution levels. This embodiment takes particular account of the complex shaping of components in additive processes and makes it possible to address design requirements and increase process efficiency even in preparation for manufacturing, while shortening assembly time.

[0020] In one embodiment, the component geometry is separated, subdivided, or divided into at least two sub-geometries per component section based on the analysis. In this way, the surface quality can be maintained, even for each component section, while the overall manufacturing efficiency can be significantly improved.

[0021] In one embodiment, different component sections include those with and without overhangs. This means that during the examination (and subdivision) of the component geometry according to this embodiment, overhanging areas are specifically examined and separated with regard to the manufacturing area. A person skilled in powder bed-based additive manufacturing will readily recognize that overhanging areas require particular care in terms of manufacturing technology and must be processed using special “tailor-made” parameters. Due to the difficulty of dissipating the heat input required for solidification and also of providing sufficient mechanical support for these overhanging areas during the process, a heat input that defines the melt pool expansion and a layer thickness must be kept within very narrow working ranges.For overhang angles which, measured from a normal of the manufacturing surface (see below), exceed 45°, it is often not possible to reproduce the corresponding overhangs in manufacturing technology.

[0022] In one embodiment, the component geometry comprises an overhanging component section, wherein a variable geometric width is assigned to this section during separation into component sub-geometries depending on the overhang angle, at least in an outer region. The variable geometric width preferably defines the outer sub-geometry and thus the corresponding region of the component which is processed with the second, i.e. smaller, layer thickness. The dimension of the said geometric width expediently relates in the present case to a plan view of the manufacturing surface, i.e. a cross-section of the component design.

[0023] In one embodiment, the overhanging component section in the outer region, i.e., preferably the outer sub-geometry of this section, is assigned a relatively large geometric width for a flat (or strong) overhang and a smaller geometric width for a steeper overhang. As described in the specific embodiments below, this embodiment offers the significant advantage for process efficiency of being able to determine the requirement for a correspondingly adjustable layer thickness by defining the geometric width.

[0024] A further aspect of the present invention relates to a computer program product obtained by the described method, and in particular as part of or comprising a CAM file, is configured for controlling an additive manufacturing process. The computer program product comprises, in particular, instructions which, when the corresponding program is executed by a computer or a process controller in an additive manufacturing system, cause the computer or process controller to carry out the described method.

[0025] A CAD file or a computer program product can be provided or present, for example, as a (volatile or non-volatile) storage or playback medium, such as a memory card, a USB stick, a CD-ROM or DVD, or in the form of a downloadable file from a server and / or in a network. The provision can also be made, for example, in a wireless communications network by transferring a corresponding file with the computer program product. A computer program product can contain program code, machine code or numerical control instructions, such as G-code and / or other executable program instructions in general.

[0026] A further aspect of the present invention relates to an additive manufacturing method, comprising the described method for process preparation, wherein the computer program product including the component geometry separated thereby is transferred or exported as a CAM manufacturing instruction, for example to a machine control of an additive manufacturing system, and the component is manufactured additively accordingly.

[0027] A further aspect of the present invention relates to a control system for an additive manufacturing system, which is configured to execute the computer program product as a manufacturing instruction or to control the additive manufacturing system accordingly for the manufacturing process of the component.

[0028] Embodiments, features and / or advantages which in the present case relate to the method for process preparation or the computer program product may also relate to the additive manufacturing system as well as to the control system, and vice versa.

[0029] The term "and / or" or "respectively" as used herein, when used in a series of two or more elements, means that any one of the listed elements may be used alone, or any combination of two or more of the listed elements may be used.

[0030] Further details of the invention are described below with reference to the figures.

[0031] Figure 1 shows a schematic side view of the design of a component to be manufactured additively.

[0032] Figure 2 shows a schematic perspective view of the design of Figure 1 .

[0033] Figure 3 shows a schematic plan view of a component section of the design from Figure 1 along section AA.

[0034] Figure 4 shows a schematic plan view of another (overhanging) component section of the design from Figure 1 along section BB .

[0035] Figure 5 shows a schematic plan view of the overhanging component section of the design from Figure 1 along section CC .

[0036] Figure 6 shows a schematic side view of the overhanging component section with further details.

[0037] Figure 7 illustrates exemplary parameters and geometric relationships relevant to the manufacturing process using a schematic sketch. Figure 8 illustrates, among other things, method steps according to the invention using a schematic flow chart.

[0038] In the exemplary embodiments and figures, identical or equivalent elements may be provided with the same reference numerals. The illustrated elements and their relative sizes are generally not to scale; rather, individual elements may be exaggeratedly thick or oversized for clarity and / or clarity.

[0039] Figure 1 shows an example CAD component geometry 10 of a component to be additively assembled. The desired component should preferably be manufactured using a powder-bed-based (layer-by-layer) manufacturing process.

[0040] The component geometry 10 is divided into sub-areas or sub-sections 10 ' and 10 '' . The left-hand section 10 ' concerns a largely simple design with a square cross-section (cf. Figure 2 below), whereas the section 10 '' shown on the right in the illustration branches off from the trunk of the first section from a certain construction height (cf. reference symbol z).

[0041] Furthermore, section 10 ' ' relates to an overhanging area with respect to a manufacturing surface (not explicitly marked here). The sections A, B and C shown in dashed lines in Figure 1 are shown and described in plan views in Figures 2, 4 and 5 respectively below.

[0042] Figure 2 shows a plan view of a cross section of the component design according to section AA. For the sake of simplicity, a solid example structure is shown which is divided into two example sub-geometries or component regions by the inventive method described in more detail in Figure 8. In the interior of the design, a first sub-geometry 10'i is shown in rectangular form. The component region accordingly has a rectangular structural cross-section. Bordering this inner region is a second sub-geometry 10'o which is different from the first sub-geometry. A constant width (geometry width) of this edge region is indicated by the reference symbol a.

[0043] The said areas or sub-geometries are expediently subdivided by the method according to the invention (in preparation for the process) after the entire component design 10 has been imported accordingly, for example, into a CAM environment and / or a build processor and examined for process or surface requirements, such as overhangs and thin structural walls.

[0044] According to the invention, the first (inner) sub-geometry is processed with a first layer thickness or is set during the process. Analogously, the second sub-geometry is processed with a second layer thickness d2 (cf. Figure 7 below) which is different from the first layer thickness d1 and is preferably smaller, in particular half as large as the first layer thickness d1. In the present example, the subdivision according to the invention has the advantage that the first sub-geometry 10'i can be implemented with a larger set layer thickness (cf. d1) without having to fear any disadvantages in the structure or resolution quality, in order to make production faster and more efficient. The second sub-geometry 10'o (edge ​​region) often requires better structure resolution or surface quality, so that here a smaller layer thickness (cf. d2) must be selected depending on the specification.

[0045] In detail, the process can, for example, proceed as follows: first, a layer of raw material powder is applied (deposited) according to the smaller layer thickness d2 to be selected, and then exposed according to parameters such as energy density or irradiation power, scanning speed, hatch distance, or the like. Furthermore, a further coating step can follow in the physical manufacturing process, which distributes the powder, for example, over the inner and outer sections. Subsequently, for example, only the outer region, or the region with more complex resolution quality, is exposed, and exposure of the thicker powder layer is postponed.Due to the possibility of selecting different process or construction parameters in different sub-areas of the component in some conventional manufacturing plants, the invention described here, which further extends the parameter space to the parameter of the layer thickness, can be exploited in a process-efficient manner.

[0046] Figure 3 shows a perspective view of the component design 10, in which it can be seen that the section 10' has a square or rectangular (constant) cross-section. In contrast, the section 10" extends away from the section 10' in a quasi-cylindrical shape (with a variable cross-section).

[0047] Figure 4 shows a plan view of a cross-section of the component design according to section BB, which corresponds to a middle part of the structure between sections AA and CC. In this part of the overhanging arm 10'' the overhang is flatter than described, for example, with reference to Figure 5. In other words, an overhang angle (cf. al in Figure 6) is larger than shown, for example, in Figure 5. Due to the flat course, the process preparation for component production along section BB in the right-hand cross-sectional area 10''o requires a wider edge area, and therefore a larger width al of the sub-geometry. It is further illustrated that the width al varies over the circumference of the outer sub-geometry according to the design requirements of the component.

[0048] Figure 5 shows a top view of a cross-section of the component design according to section CC. In this part of the structure, however, the overhanging area of ​​section 10" slopes upwards more steeply. The steeper slope corresponds to a smaller overhang angle (cf. a2 in Figure 6). Accordingly, the geometry width a2 can be selected to be smaller than a1 in this specific case (and approximately constant along the circumference).

[0049] More details of this relationship are described in Figures 6 and 7. In addition to the figures described so far, Figure 6 schematically indicates the described overhang angles and melt bath dimensions M1 and M2. The flatter section along section B runs approximately at angle a1 relative to the vertical or build-up direction z; whereas the steeper section along section C extends more steeply upwards at angle a2.

[0050] In the inner region of the sub-geometry 10'i, according to section B in Figure 6, a drop-like melt pool M1 is indicated which is significantly smaller in horizontal dimensions than the melt pool M2, which is consequently defined in the region 10"i in the process in order to advantageously increase the process efficiency significantly according to the invention. The increase in efficiency and build-up time is achieved in particular by selecting a larger layer thickness (see further below), which, in conjunction with a greater energy input, can also produce a larger melt pool (deeper in the z-direction) and thus can melt and build up more volume per unit time in the interior of the component.

[0051] Referring to Figures 4 and 5, Figure 7 further shows that the flatter profile (shown bottom left) includes a wider edge geometry on the right side (cf. width a1). This parameter is smaller in the top right of the figure due to the steeper profile, indicated by width a2.

[0052] According to the invention, the outer or first sub-geometry or the edge region in the process preparation is distinguished from the inner region (second sub-geometry) in that a smaller layer thickness of approximately d2 = 40 pm can be selected than in the inner region of, for example, approximately dl = 80 pm. However, without limiting the general validity, other values ​​can also be set or selected according to the invention.

[0053] Due to the flatter overhang region, which is actually more difficult to produce in terms of manufacturing technology (cf. larger overhang angle a1), it can be seen from Figure 7 that the inner geometry can be processed more efficiently with the greater layer thickness, especially since the outer region is narrower. In other words, the construction of the flatter, larger overhanging region is more complex, and this region does not tolerate such a great degree of efficiency optimization as, for example, the steeper and easier to produce additively region (cf. 10 '' i and 10 '' o ).

[0054] Figure 8 illustrates method steps according to the invention using a schematic flow diagram. Furthermore, the reference symbol "CAM" is intended to indicate a corresponding process product, in particular a computer program product, which can be transferred to a controller 20 or an additive manufacturing system 100, for example, as an additive manufacturing instruction by way of the physical construction of the component, or can be loaded into it in order to actually produce the component more efficiently using the technical advantages imparted during the process preparation.

[0055] The geometry of the component is usually defined by a CAD file ("Computer-Aided Design"). After reading such a file into a build processor of a manufacturing plant (cf. reference numeral 100), the process then first requires the definition of a suitable irradiation strategy, for example by standard process preparation by CAM, which usually also involves, among other things, dividing the component geometry into the individual layers. The method according to the invention, on the other hand, is a method for process preparation in the additive manufacturing of a component 10. The method comprises, (i), explicitly importing a component geometry (CAD) into a CAM environment.

[0056] The method further explicitly includes the examination (ii) of the component geometry CAD for areas (10', 10'', 10'i, 10'o, 10' 'i, 10' 'o) which are to be provided with a different resolution quality in the manufacturing process.

[0057] The method further comprises (iii) separating the component geometry into at least two component sub-geometries 101, 100o based on the examination, wherein a first sub-geometry 101 is constructed in the manufacturing process with a first layer thickness dl and a second sub-geometry 100o, different from the first sub-geometry 101, is constructed with a second layer thickness d2, wherein the second layer thickness d2 is smaller, in particular half as large as the first layer thickness dl.

[0058] The said computer program product obtained by the method, and in particular as part of or comprising a CAM file, is configured for controlling an additive manufacturing process, expediently comprises instructions which, when the program is executed by a computer or a process controller 20 in an additive manufacturing system 100, cause the computer or process controller 20 to carry out the method steps.

[0059] The controller 20 for an additive manufacturing system 100, on the other hand, is configured to execute the computer program product as a manufacturing instruction or to control the additive manufacturing system 100 accordingly for the manufacturing process of the component 10.

[0060] Without loss of generality, any other component geometry can be predefined, which can then be imported, examined and separated using the described procedure; this is largely independent of wall thickness limits, overhangs or other implications.

[0061] The described component 10 may be a component preferably for use in the hot gas path of a gas turbine. For example, the component relates to a component to be cooled with a thin-walled or delicate design. Alternatively or additionally, the component may be a component for use in the automotive or aviation sectors.

Claims

Patent claims 1. A method for process preparation in the additive manufacturing of a component (10), comprising the following steps: (i) Importing a component geometry (CAD) into a CAM environment, (ii) Examining the component geometry (CAD) for areas (10', 10'', 10'i, 10'o, 10''i, 10''o) which are to be provided with a different resolution quality in the manufacturing process, and (iii) separating the component geometry into at least two component sub-geometries (101, 100) based on the examination, wherein a first sub-geometry (101) is built up in the manufacturing process with a first layer thickness (dl) and a second sub-geometry (100) different from the first sub-geometry (101) is built up with a second layer thickness (d2), wherein the second layer thickness (d2) is smaller, in particular half as large as the first layer thickness (dl), wherein the different component sections (10', 10'') comprise component sections with and without overhangs.

2. Method according to claim 1, wherein an inner region of the component geometry (101) is processed with the first layer thickness (dl), and an outer or edge region (lOo) of the component geometry is processed with the second layer thickness (d2).

3. The method according to claim 2, wherein the first layer thickness (dl) for the inner region is approximately 80 pm, and the second layer thickness (d2) for the outer region is approximately 40 pm.

4. Method according to one of the preceding claims, wherein the examination of the component geometry in regions with a different resolution quality comprises the identification of different component sections, and wherein each component section suggests the application of different process parameters in the manufacturing process.

5. Method according to claim 4, wherein the separation of the component geometry based on the examination takes place in at least two component sub-geometries (10 'i, 10 'o) per component section (10', 10'').

6. Method according to one of the preceding claims, wherein the component geometry comprises an overhanging component section (10''), wherein a variable geometry width (a) is assigned to this section during the separation into component sub-geometries depending on an overhang angle (a) at least in an outer region (10''o), and wherein the variable geometry width defines the outer sub-geometry and thus the region of the component which is processed with the second layer thickness (d2).

7. Method according to claim 6, wherein the overhanging component section (10'') in the outer region (10''o) is assigned a relatively large geometric width (al) in the case of a flat overhang (al), and a smaller geometric width (a2) in the case of a steeper overhang (a2).

8. A computer program product obtained by the method according to any one of the preceding claims, and in particular as part of or comprising a CAM file, is configured for controlling an additive manufacturing process, wherein the computer program product comprises instructions which, when the program is executed by a computer or a process controller (20) in an additive manufacturing system (100), cause the computer or process controller (20) to carry out the method steps according to claim 1.

9. Additive manufacturing process comprising the process preparation method according to one of claims 1 to 7, wherein the computer program product according to claim 8 including the component geometry separated thereby is transmitted as a manufacturing instruction (CAM) to a machine control of an additive ven manufacturing plant (100), and the component (10) is manufactured accordingly additively.

10. Controller (20) for an additive manufacturing system (100), which is configured to execute the computer program product according to claim 8 as a manufacturing instruction or to control the additive manufacturing system (100) accordingly for the manufacturing process of the component (10).

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