DE102021202852A1 - Additively manufactured fluid-permeable material structure - Google Patents

Abstract

An additively produced material structure (10) for a turbine component (20, 30) is specified, the material structure (10) comprising a solid material lattice (11) and a porous functional material (12), the functional material (12) in lattice interstices (13 ) of the material grid (11) and wherein the functional material (12) is designed so that a fluid (F) can flow through it during intended use of the component. Furthermore, a corresponding turbine component as well as a method and a computer program product for producing the material structure (10) are specified, with construction parameters (V, p, v, o, a, d) for a solid material for the solid material lattice (11) and with for the Functional material porosity-generating structure parameters (V, p, v) are selected.

Description

The present invention relates to an additively manufactured or manufacturable turbine component that is subjected to high thermal loads, and also to a material or composite structure for a particularly mechanical and/or corresponding manufacturing method. Furthermore, the invention relates to the turbine component itself and a computer program product containing manufacturing instructions with which the method can be carried out.

The component is preferably intended for use in the hot gas path of a gas turbine. For example, the component relates to a component to be cooled. Alternatively or additionally, the component can be a component for use in automobiles or in the aviation sector.

High-performance machine components are the subject of constant improvement, in particular to increase their efficiency in use. In the case of heat engines, in particular gas turbines, however, this leads, among other things, to ever higher operating temperatures. The metallic materials and the component design of heavy-duty components such as turbine blades or other hot gas parts are constantly being improved in terms of their strength, service life, creep resistance and thermomechanical fatigue.

Due to technical advances, generative or additive manufacturing is also becoming increasingly interesting for the series production of the above-mentioned components, such as turbine blades or burner components. Additive manufacturing processes (AM: "additive manufacturing") have proven to be particularly advantageous for complex or filigree 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 manufacturing step of a component can be carried out largely on the basis of a corresponding CAD file and the selection of corresponding manufacturing parameters.

A method for selective laser melting with pulsed radiation is known, for example, from EP 3 022 008 B1 .

Additive manufacturing processes, also known colloquially as 3D printing, include, for example, selective laser melting (SLM) or laser sintering (SLS) or electron beam melting (EBM) as powder bed processes.

The production of gas turbine blades using the described powder bed-based process (LPBF for “Laser Powder Bed Fusion”) advantageously enables the implementation of new geometries, concepts, solutions and/or designs that reduce the manufacturing costs or the construction and throughput time, optimize the manufacturing process and, for example, improve a thermo-mechanical design or durability of the components. Components manufactured in a conventional way, for example by casting, are significantly inferior to the additive manufacturing route, for example in terms of their freedom of shape and also in relation to the required throughput time and the associated high costs and the manufacturing effort.

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 leads to distortion of the structure. Severe warping during the build process easily leads to structural delamination, thermal distortion, or geometric deviations outside of allowable tolerances.

Nevertheless, additive manufacturing, for example via LPBF, even enables the production of porous structures, which, for example, enable efficient cooling or the ability for a fluid to flow through when the corresponding component is used. Compared to additively produced solid material structures, these (porous) or functional structures can absorb less mechanical load due to their reduced material content. This usually results in limited use and operation of the component.

It is therefore an object of the present invention to specify means for a novel additively manufactured material structure with which the technical difficulties mentioned can be overcome. In particular, the material structure presented is intended to provide a solution for cooling and/or damping concepts in highly stressed components, with corresponding components produced from this material being able to withstand sufficient mechanical and/or thermal loads at the same time.

This object is solved by the subject matter of the independent patent claims. Advantageous configurations are the subject matter of the dependent patent claims.

One aspect of the present invention relates to an additively manufactured material structure for a component, in particular a turbine core component, wherein the material structure comprises a solid material lattice and a porous functional material, wherein the functional material is also arranged in lattice interstices of the material lattice and wherein the functional material is designed so that a fluid, such as a cooling fluid, can flow through it during intended use of the component. Preferably, the solid lattice of material provides improved mechanical properties, such as increased strength, elongation at break, or the like. Mechanical properties of the components can advantageously be significantly improved by the configuration of the material structure. At the same time, functional properties of the material can be refined or better utilized thanks to its improved structure, and the additive manufacturing route can be validated for even more complex components at the same time.

In one embodiment, the material structure consists of an, in particular regular, cohesive composite of the material lattice and the functional material. This integral, advantageous mechanical connection implemented via the corresponding additive manufacturing process enables the excellent mechanical properties of the material structure, including an advantageous resilience of the structure, for example to dynamic loads, with simultaneous weight reduction.

In one configuration, a thickness or strength of lattice elements, such as lattice struts, of the material lattice is between 0.3 mm and 1 mm. The proposed structure can be developed advantageously down to this “resolution”.

In one configuration, a pore size, for example an average, of pores in the functional material is smaller than an average size or an average diameter of lattice elements of the material lattice, such as the lattice struts described.

In one configuration, a lattice parameter or a lattice constant, for example a cell length of the material lattice, is between 2 and 5 mm.

A further aspect of the present invention relates to a turbine component comprising the material structure described, the component being a component of the hot gas path of a gas turbine, for example a component to be cooled or a damper component. Such a damping component can be a Helmholtz resonator, for example, in particular for (thermo-acoustic) damping of combustion chamber vibrations or combustion instabilities in turbine operation.

A further aspect of the present invention relates to a turbine comprising the turbine component described.

A further aspect of the present invention relates to a method for producing the material structure, the material structure being built up additively from a powder bed, preferably by selective laser melting, with structure parameters that produce solid material for the material lattice and structure parameters that produce porosity for the functional material being selected, and with irradiation paths which are the fabrication of the material grid and the functional material (as part of the build parameters) can be chosen to overlap by an amount between 0.2 mm and 0.5 mm. Advantageously, the method allows the parametrical setting of permeability properties of the functional material and thus a specific packaging of the cooling capacity and/or damping properties of the component. Furthermore, additive manufacturing advantageously allows the mechanical strength of the material lattice to be adjusted via a corresponding selection of construction or irradiation parameters.

In one embodiment, construction parameters are chosen in such a way that radiation paths, which are chosen for the production of the material grid and the fusion material, completely overlap. This configuration can advantageously produce a particularly rigid mechanical connection and/or material connection between the material lattice and the functional material.

A further aspect of the present invention relates to a computer program product, comprising instructions which, when a corresponding program is executed by a computer, for example for controlling the irradiation in an additive manufacturing system, cause this to select the construction parameters and/or execute the selective irradiation of a perform powder bed.

In one embodiment, the computer program product relates to manufacturing instructions according to which an additive manufacturing system is controlled by a corresponding computer program for manufacturing the component, for example using CAM (computer-aided manufacturing) means.

Such a computer program product can, for example, be in the form of 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 are provided or are available. The provision can also be made, for example, in a wireless communication network by transferring a corresponding file with the computer program product. The computer program product may include program code, machine code or numerical control instructions such as G-code and/or other executable program instructions in general. The computer program product can also contain geometry data and/or design data in a data set or data format, such as a 3D format or as CAD data, or can include a program or program code for providing this data.

Configurations, features and/or advantages that relate to the material structure or the component in the present case can also directly relate to the additive manufacturing method or the computer program product, and vice versa.

As used herein, the term "and/or" when used in a series of two or more items means that each of the listed items can be used alone, or any combination of two or more of the listed items can be used.

• 1 zeigt eine schematische perspektivische Abbildung einer gitterartigen Materialstruktur für eine Turbinenkomponente.
• 2 zeigt eine schematische Aufnahme eines Teils einer erfindungsgemäßen additiv hergestellten Materialstruktur, umfassend ein Materialgitter sowie ein in Gitterzwischenräumen des Gitters angeordnetes Funktionsmaterial.
• 3 zeigt eine zur Abbildung der 2 ähnliche Materialstruktur in einer anderen Ausgestaltung.
• 4 zeigt beispielhafte Spannungskennlinien von additiv hergestellten Strukturen.
• 5 deutet anhand einer schematischen Schnittansicht grundlegende Verfahrensschritte eines pulverbett-basierten additiven Herstellungsverfahrens an.

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

• 1 shows a schematic perspective illustration of a lattice-like material structure for a turbine component.
• 2 shows a schematic photograph of part of an additively manufactured material structure according to the invention, comprising a material lattice and a functional material arranged in the interstices of the lattice.
• 3 shows an illustration of the 2 similar material structure in a different configuration.
• 4 shows exemplary voltage characteristics of additively manufactured structures.
• 5 indicates the basic process steps of a powder bed-based additive manufacturing process using a schematic sectional view.

In the exemplary embodiments and figures, elements that are the same or have the same effect can each be provided with the same reference symbols. The elements shown and their proportions to one another are not to be regarded as true to scale; instead, individual elements may be shown with exaggerated thickness or dimensions for better representation and/or better understanding.

1 1 schematically shows an additively manufactured material structure 10. The material structure 10 is preferably provided for a component 20 or 30 and comprises a solid material grid 11 which is provided for mechanical support or stability of the structure 10 or a component area of the component. The material structure 10 is preferably used in a turbine component 20 of the hot gas path of a gas turbine 30 . For example, component 20 may relate to a damper component such as a Helmholtz resonator. Accordingly, advantages of the present invention already result from the design or additive manufacturing of the structure 10 and manifest themselves in the use of the turbine component 20 or even the superordinate turbine 30, which is equipped with a turbine component 20 that is improved in terms of material technology.

Alternatively, the component 20 can be another part 20 of a turbomachine. In particular, the component can be a blade or vane, a ring segment, a combustion chamber or burner part, such as a burner tip, a skirt, a shield, a heat shield, a nozzle, a seal, a filter, an orifice or lance, a stamp or a designate swirlers, or a corresponding aftermarket part.

As per the description of the 5 explained in more detail, the structure 10 or the entire component 20 is preferably produced by a powder bed process, for example LPBF.

The horizontal dashed arrow, which is identified by the reference character F, is intended to indicate that at least a region of the component 20 in which the material structure 10 is present preferably has fluid-permeable properties and between the lattice struts of the material lattice 11, as intended, with a cooling fluid can be flowed through.

How based on 2 As can be seen, the material structure 10 according to the invention also comprises a porous functional material 12, the functional material 12 being arranged in lattice interstices 13 of the material lattice 11. For this purpose, the material structure 10 is preferably formed from a cohesive composite of the material grid 11 and the functional material 12 (see below).

A thickness d of lattice struts or lattice elements of the material lattice 11 is preferably between 0.3 mm and 1 mm. In this way, for example in connection with the selection of the lattice parameters, an optimal mechanical strength of the structure 10 can be achieved. A lattice parameter a of the material lattice 11, in particular a lattice cell length, is preferably between 2 mm and 5 mm. An average pore size (not explicitly marked in the figures) of pores P of the functional material 12 is expediently smaller than an average size of lattice elements of the material lattice 11.

The present invention thus proposes a combination of lattice structures and porous structures. The invention combines the improved mechanical properties of the lattice and the functional properties of the porous functional material, for example with regard to the described parametrically adjustable flowability and functional properties. In the underlying additive manufacturing process (cf 5 below) different process or structure parameters are assigned to the mentioned areas. The lattice structures 11 are given so-called solid material parameters, for example via a corresponding control program or computer program product, whereas the porous material is manufactured with structural parameters that create porosity.

In this case, the two partial structures can overlap completely for a good connection, or only an edge or overlapping area o of, for example, between 0.2 mm and 0.5 mm can overlap or overlap. The latter can be accomplished via an overlap of structure parameters, in particular of irradiation vectors (see below) for the structure structure. The choice or amount of overlap may depend on the dimension of the grid braces.

Alternatively, irradiation paths, which are selected as part of the construction parameters for the production of the material grid 11 and the functional material 12, can completely overlap.

3 shows a to 2 similar figure showing an alternative pattern for the lattice regions 11 and the functional regions 12 of the material structure 10. FIG.

Opposite of 2 , which shows a two-dimensional, rectangular (regular) grid with corresponding functional “material fillings”. 3 a somewhat more complex configuration, with round or spherical lattice interstices 13 being defined by the material lattice 11, in which the functional material 12 is then arranged.

The properties of this tailor-made functional material can be varied or customized across all possible process parameters. It is provided that - unlike in the 2 and 3 shown - the material structure is actually three-dimensional.

4 clarifies the advantages according to the invention of the material structure 10 presented, as described above, on the basis of stress-strain characteristics of three different structures.

In the lower characteristic curve, the course of a porous material is shown without a supporting structure, ie without a material lattice. It is in 4 furthermore, it can be seen that the mechanical strength or tension S of the materials that comprise the material structure 10 according to the invention (see the top two characteristic curves) has been significantly increased; in the case of the structure shown on the right, even by 100% (cf. y-axis).

Furthermore, in 4 to see that the elongation at break (cf. x-axis) for the upper right in the 4 The structure shown could be increased by 65%, which is of particular advantage for vibrating or dynamically loaded components.

It should be noted that all three materials examined were constructed with the same irradiation parameters for the porous functional material.

5 10 shows an additive manufacturing system 100. The system 100 is preferably designed as an LPBF system and for the additive construction of parts or components from a powder bed. The system 100 can in particular also relate to a system for electron beam melting.

Accordingly, the system has a construction platform 6 . A material structure 10 to be produced additively for a component 20 is produced in layers from a construction material 1 on the construction platform 6 . The latter is formed by a powder P, which can be distributed in layers on the construction platform 6 by a coating device 3 or can be doctored on.

After the application of each powder layer L (cf. layer thickness t), according to the given geometry of the component 20, selective areas of the layer are melted with an energy beam 5, for example a laser or electron beam, from an irradiation device 2 and then solidified.

After each layer L, the construction platform 6 is preferably lowered by an amount corresponding to the layer thickness L (cf. arrow pointing downwards in 1 ). The thickness L is usually only between 20 µm and 40 µm, so that the entire process can easily be selectively irradiated from thousands to tens of thousands of layers.

According to the method of the present invention, a set of parameters can preferably be implemented in terms of production technology via a controller 4, for example of the irradiation device 2, by selecting appropriate construction parameters. For this purpose, the controller 4 can be computer-aided and have, for example, a data processing device or a processor. The parameters or instructions are preferably provided by a computer program product CP. This includes commands which, when a corresponding program is executed by a computer or the controller 4 of the beam 5 in the system 100, cause the latter to select the construction parameters and/or to carry out the selective irradiation of a powder bed 1.

The geometry of the component is usually defined by a CAD file (“computer-aided design”). After such a file has been read into the manufacturing system 100, the process then first requires the definition of a suitable irradiation strategy, for example by means of the CAM, which also results in the component geometry being divided into the individual layers.

The method is therefore an additive method for producing the material structure 10, preferably by selective laser melting, with structure parameters for a solid material being selected for the solid material lattice 11 and with structure parameters that create porosity being selected for the functional material.

The parameters or CAM instructions mentioned preferably include a large number of individual irradiation vectors V for the irradiation of a layer L, an irradiation pattern formed accordingly, an irradiation speed v, an irradiation power p, a hatching or grid spacing (not explicitly marked), and the described beam -, grid, or melt bath overlap o. By defining these and possibly other parameters, the component 20 can advantageously be equipped with tailor-made mechanical properties and permeability properties.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3022008 B1 [0005]

Claims (10)

Additively produced material structure (10) for a component (20, 30), the material structure (10) comprising a solid material lattice (11) and a porous functional material (12), the functional material (12) in lattice interstices (13) of the material lattice ( 11) and wherein the functional material (12) is designed so that a fluid (F) can flow through it during intended use of the component. Material structure (10) according to claim 1 , wherein the material structure consists of a cohesive composite of the material grid (11) and the functional material (12). Material structure (10) according to claim 1 or 2 , wherein a thickness (d) of lattice elements of the material lattice (11) is between 0.3 mm and 1 mm. Material structure (10) according to one of the preceding claims, wherein an average pore size of pores (P) of the functional material (12) is smaller than an average size of lattice elements of the material lattice (11). Material structure (10) according to one of the preceding claims, wherein a lattice parameter (a) of the material lattice (11), in particular a lattice cell length, is between 2 mm and 5 mm. A turbine component (20) comprising a material structure (10) according to any one of the preceding claims, wherein the component is a component of the hot gas path of a gas turbine, for example a damper component. Turbine (30) comprising a turbine component (20) according to claim 6 . Method for producing a material structure (10) according to one of the preceding claims, in which the material structure is built up additively from a powder bed (1), preferably by selective laser melting, in which construction parameters (V, p, v, o ), and where porosity-generating structure parameters (V, p, v) are selected for the functional material, and where irradiation paths (V), which are selected for the production of the material grid (11) and the functional material (12), are selected by a measure of between 0 .2 mm and 0.5 mm overlap (o). procedure according to claim 8 , wherein irradiation paths (V), which are selected for the production of the material grid (11) and the functional material (12), completely overlap. Computer program product (CP), comprising instructions which, when a program is executed by a computer, for example for controlling the irradiation in an additive manufacturing system (100), cause the latter to select the construction parameters (V, p, v, o, a, d ) and/or the execution of the selective irradiation of a powder bed (1) according to the method claim 8 or 9 to perform.

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