Patent Application
20220008997
The present invention relates to a regulation method for the additive manufacturing of a component, such as in powder-bed-based manufacturing. An apparatus, a computer program product and a method for the additive manufacturing of the component, which uses the regulation described, are also specified.
The component may be intended for use in a turbomachine, in particular in the hot gas path of a gas turbine. The component may consist of a superalloy, in particular a nickel-based or cobalt-based superalloy. The alloy can be, for example, precipitation hardened or solid solution hardened.
In gas turbines, thermal energy and/or flow energy of a hot gas generated by burning a fuel, for example a gas, is converted into kinetic energy (rotational energy) of a rotor. For this purpose, a flow channel is formed in the gas turbine, in whose axial direction the rotor or a shaft is mounted. If a hot gas flows through the flow channel, a force is applied to the rotor blades and is converted into a torque which acts on the shaft and drives the turbine rotor, wherein the rotational energy can be used, for example, to operate a generator.
Modern gas turbines are the subject of constant improvement in order to increase their efficiency. However, this leads, among other things, to ever higher temperatures in the hot gas path. The metallic materials for rotor blades, especially in the first stages, are constantly being improved with regard to their strength at high temperatures (creep load, thermomechanical fatigue).
Due to its disruptive potential, generative or additive manufacturing is also becoming increasingly interesting for the industrial series production of the above-mentioned turbine components, for example turbine blades or burner components.
Additive manufacturing methods include, for example, as powder bed methods, selective laser melting (SLM) or laser sintering (SLS), or electron beam melting (EBM).
A method for selective laser melting is known, for example, from EP 2 601 006 B1.
Additive manufacturing methods have also proven to be particularly advantageous for complex components or components of complicated or filigree design, 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 production or manufacturing step of a component can largely take place on the basis of a corresponding CAD file and the selection of appropriate manufacturing parameters.
The term “computer program product” described herein can represent or include a computer program means, for example, and can be provided or included, for example, as a storage medium, for example a memory card, a USB stick, a CD-ROM, a DVD, or else in the form of a downloadable file from a server in a network. This may take place, for example, in a wireless communication network through the transmission of an appropriate file comprising the computer program product or the computer program means.
An ubiquitous problem with additive manufacturing methods for highly stressed or highly stressable components are the structural properties or material properties which are often inferior to conventional manufacturing techniques. In order to achieve better material properties in additive manufacturing, a further heat source can be used in addition to the laser to better control the heating and cooling behavior. When processing metals, especially superalloys, induction heating systems are suitable for this purpose, but, due to the uneven application of the heating power, additionally require mechanical positioning of the induction coil(s).
The heating power must likewise be controlled, since the geometry has a very strong influence on the heating or the coupling efficiency or effect of the heating. For temperature regulation and/or capture, it is possible to use an infrared camera which overlooks or can capture the entire construction site (of an AM system). The image information can be converted into a temperature via calibration and can be evaluated, for example, at the position of the coils. It is possible that only a fixed position (“region of interest”) within the image is evaluated here and can then be shifted from one position to the next in the image with the coil. This temperature can also be transferred to a regulator or a regulation device with fixed parameters. After a position shift, for example in order to heat a further region of a layer which has been constructed or is to be constructed during the manufacturing of the component, the coil typically reaches another (cold) point and regulates the heating power again.
The regulation used in conventional heating systems often includes a pyrometer which is carried with a coil for inductive heating, is aimed at a fixed, for example through the coil eye, and is regulated with fixed regulation parameters, for example of a PID regulator. The pyrometer by means of via the size of the measurement spot and an evaluation within the measurement spot does not take place.
One problem that arises is that the image from an infrared camera, a thermal imaging camera or a thermographic device does not provide an ideal image, but rather the individual captured “pixels” have a lot of noise. In addition, the temperature in the vicinity of the coil or in the vicinity of the corresponding region of the layer is not constant, but is highly location-dependent or position-dependent. Therefore, on the one hand, the “region of interest” must be chosen to be large enough to cover the relevant region as far as possible. In addition, not only a single pixel (for example the maximum) may be evaluated, since this value fluctuates greatly and this makes regulation more difficult. For stable regulation, there is therefore a need for a solution which, on the one hand, supplies a reliable value close to the maximum within the region of interest, but is not subject to the noise behavior of an individual pixel.
It is therefore an object of the present invention to specify means which solve the problem described above.
This object is achieved by means of the subject matter of the independent patent claims. The dependent patent claims relate to advantageous configurations.
One aspect of the present invention relates to a regulation method or a method for regulating or providing regulation data for the additive manufacturing of a component, in particular powder-bed-based manufacturing.
The method comprises capturing spatially resolved temperature data or temperature values of an additively constructed layer (component layer) during the manufacturing of the component. For this purpose, the data or values mentioned are advantageously captured and/or stored at a plurality of positions of the layer or on the layer.
This layer mentioned can denote one of several hundred or thousand layers which are additively constructed one after the other via powder bed processes by selective irradiation with a laser or energy beam.
The term “during” in connection with the additive manufacturing of the component is intended to mean in the present case that, for example, although a layer is processed overall during the manufacturing of the component, it is advantageously processed by the processing apparatus (in layers) after the respective solidification of the layer.
The method also comprises determining at least one defined region of interest of the layer which is intended to be processed during the manufacturing of the component.
The region or the region of interest advantageously denotes a selected geometric region looking down on the respective constructed layer. The region also expediently denotes a region in which the temperature data are intended to be captured, stored or evaluated. The region of interest is advantageously defined by defined but subsequent processing of the layer, that is to say after the determination, in particular by coordinates of a movable processing device (see further below).
The method also comprises classifying, selecting or dividing temperature values of the at least one region of interest, for example on the basis of at least one defined class of temperature values. This classification can take place in the manner of a histogram, with a set of values being divided into classes based on the class width.
The method also comprises forming a mean value of the classified temperature values. The mean value can be, for example, an arithmetic, a geometric or a quadratic mean value.
The method also comprises controlling or regulating a processing device with the formed mean value as an input value in order to process the layer. The processing can advantageously mean preheating or heating of the layer in the region of interest. In the present case, processing by preheating can also relate to a layer of the component that has not yet solidified or been constructed, but rather to a freshly applied base material layer for the component.
The means described in the present case are advantageously suitable for processing or preheating the component or a component layer to be subsequently manufactured to a temperature of over 1000° C.
In one configuration, the mean value of the classified temperature values is an arithmetic mean value. Alternatively, the mean value can be a geometric or a quadratic mean value.
In one configuration, the mean value is transferred as an actual value to a regulation system or regulation device, in particular comprising a PID regulator, or is used accordingly. Said regulator can be implemented both in terms of software and in terms of hardware.
The method described enables, for example, a simplification compared to temperature regulation in additive manufacturing or another application with a movable pyrometer that is carried along, since the carriage of the pyrometer must be moved from a first position to a second position on the layer, for example.
Nevertheless, the evaluation of the captured temperature values in the region of interest allows, for example, in contrast to the embodiment with a pyrometer, a dynamic or time-dependent evaluation of the individual pixels or temperature values. Such functionality could only be achieved with pyrometers via a combination of a plurality of instruments or systems.
Furthermore, a significantly improved noise behavior can be achieved with the regulation means presented.
In one configuration, the method is a computer-implemented method.
In one configuration, the temperature values or temperature data are captured by means of an infrared camera, a thermal imaging camera or thermographically, for example using appropriate thermographic temperature capture means. This configuration is preferred since many conventional additive manufacturing systems are already equipped with appropriate devices for measuring temperatures or recording temperature images.
In one configuration, the temperature data or values of the layer are captured only in one (or more) region(s) of interest, but not, for example, in other regions of the layer or of the thermal image. This configuration is process-efficient and data-efficient and allows the regulation effort to be minimized.
In one configuration, the temperature values are calculated or determined from the temperature data. The temperature data can deviate from the temperature values to the extent that the temperature data can advantageously describe a temperature or thermal image from which the corresponding specific temperature values first have to be extracted or converted.
In one configuration, a histogram of temperature values is created.
In one configuration, an absolute or relative class frequency of the temperature values is determined for the classification. For the determination or construction of the histogram, the temperature values are divided, selected or classified, for example on the basis or with the aid of a defined class width.
In one configuration, the 10% of the temperature values that are largest, in particular in terms of absolute value, are classified or selected or preselected from the at least one region of interest. This configuration corresponds to that of a histogram in which the areas of the individual rectangles or classes denote the relative class frequencies.
In one configuration, the temperature values are classified or selected, for example preselected, in particular in terms of absolute value, from a range of the largest 10 to, for example, the largest 50 values from the at least one region of interest. This configuration corresponds to that of a histogram in which the areas of the individual rectangles or classes denote the absolute class frequencies.
In the present case, the temperature values mentioned are advantageously cardinally scaling values.
In one configuration, the processing apparatus comprises an induction heating apparatus for preheating the layer.
In one configuration, the processing apparatus comprises a regulation system, in particular a PID regulation system, which receives the mean value as an input value.
In one configuration, a multiplicity of selected areas or regions of interest are determined and/or processed in the additive manufacturing of the component. According to this configuration, the method described can be used particularly expediently and effectively.
In one configuration, the regulation system regulates the induction heating apparatus at least partially continuously, dynamically or as a function of time. This configuration enables particularly precise and rapid regulation of the preheating or processing, with the result that a corresponding additive manufacturing process can be decisively improved with regard to the achievable material structure of the component and the process time.
Another aspect of the present invention relates to an apparatus for controlling the processing device, in particular an induction heating apparatus, which has, for example, two induction coils that can be moved independently of one another. The apparatus comprises means for carrying out the regulation method as described above. These means can be a computer program, a computer program product, a data structure product or other corresponding computer program means.
The apparatus also comprises a temperature capture device, advantageously an infrared camera or a device for thermographically capturing temperature data. In this way, a temperature image of an additively constructed layer can be determined in a particularly simple and expedient manner and temperature data can be captured particularly easily and quickly.
The apparatus also comprises a regulation device, in particular comprising a PID regulator. Alternatively, the regulation can be carried out with a PI regulator, a PD regulator or another regulator or another regulation device.
In one configuration, the apparatus is part of an additive manufacturing system, in particular a system for powder-bed-based additive manufacturing or production.
Another aspect of the present invention relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out at least one of the above-described method steps of the regulation method, i.e. determination, classification, formation of the mean value and/or control. The computer program product can, for example, comprise corresponding computer program means which are required in order to run, for example, corresponding algorithms for solving the problem described.
Another aspect of the present invention relates to a computer-readable medium on which the above-mentioned computer program or computer program product or parts thereof can be stored.
Another aspect of the present invention relates to a method for the additive manufacturing of a component, comprising the layer-by-layer additive construction of the component from a pulverulent base material, wherein, after or during the solidification of a powder layer by means of an energy beam, this layer is processed using the regulation method as described. The particular advantages of the regulation according to the invention are particularly evident in the actual construction process in the material structure of the component which is improved by the heat management.
In one configuration, a temperature capture device or a camera is moved or concomitantly moved from a first position to a second position during the additive manufacturing of the component. The first position can describe a first region of interest. The second position can describe a second region of interest.
In another configuration, at least one region of interest is (concomitantly) moved from a first position to a further or second position, for example by software or program technology, during the additive manufacturing of the component.
Another aspect of the present invention relates to a component which is manufactured or can be manufactured according to the method for additive manufacturing. For example, in contrast to a conventionally manufactured component from the prior art or an additively manufactured component from the prior art, the component comprises a largely crack-free and/or low-stress, in particular monocrystalline and/or columnar crystalline, microstructure.
Configurations, features and/or advantages which in the present case relate to the regulation method, the computer program product or the apparatus can—as explained—also relate to the additive manufacturing process or the component itself, or vice versa.
Further features, properties and advantages of the present invention are explained in more detail below on the basis of exemplary embodiments with reference to the accompanying figures. All of the features described so far and below are advantageous both individually and in combination with one another. It goes without saying that other embodiments can be used and structural or logical changes can be made without departing from the scope of protection of the present invention. The following description therefore should not to be interpreted in a restrictive sense.
The term “and/or” used here, when used in a series of two or more elements, means that any of the listed elements can be used alone, or any combination of two or more of the listed elements can be used.
In the exemplary embodiments and figures, identical or identically acting elements can each be provided with the same reference signs. The elements shown and their proportions to one another are fundamentally not to be regarded as true to scale; rather, individual elements can be shown exaggeratedly thick or with large dimensions for better presentability and/or for better understanding.
A starting or base material B for the component 10 is selectively irradiated and solidified in layers by an energy beam, advantageously a laser beam 105, in accordance with the desired (predetermined) geometry. For this purpose, the component is manufactured on a substrate or a construction platform 12 or welded to it.
The platform 12 simultaneously serves as a mechanical support during manufacturing in order to protect the component from thermal distortion. After the solidification of each layer, a manufacturing surface (not explicitly identified) is newly coated with powder B, advantageously by a coater 11, and the component is constructed further in this way. Layers 1 and 2 are indicated by dashed lines in
The component 10 is advantageously a component which is used in the hot gas path of a turbomachine, for example a gas turbine. In particular, the component can be a rotor or guide blade, a segment or ring segment, a burner part or a burner tip, a frame, a shield, a heat shield, a nozzle, a seal, a filter, an orifice or lance, a resonator, a stamp or an agitator, or a corresponding transition, insert, or a corresponding retrofit part. Accordingly, the component 10 is advantageously a component that is thermally and/or mechanically highly stressed in its intended operation and is made of a superalloy, for example a cobalt-based or nickel-based superalloy.
A processing device 20 is also indicated on the right-hand side of a manufacturing surface (on the right in the figure). The processing device 20 can be used to expediently be pretreat and/or post-treat a newly applied powder layer or a freshly solidified or irradiated component layer. This processing is particularly advantageous or expedient in order to carry out an advantageous or necessary heat treatment (heat management) of the corresponding components, advantageously in-situ and/or during construction.
The large process-inherent temperature gradients in powder-bed-based processes often exceed 104 K/s and accordingly cause high chemical imbalances, cracks and/or mechanical stresses. It is therefore expedient, for example, to thermally process a newly applied powder layer (see reference sign 2) or an already fully solidified component layer (see reference sign 1) with a processing device (see reference sign 20).
The means described in the present case for the processing or the processing device 20 are advantageously suitable for heating a processing or preheating of the component 10 or a component layer 2 to be subsequently manufactured to a temperature of over 1000° C.
According to the illustration in
In contrast to
A conventional additive manufacturing system (see reference sign 200 in
Via a computer 102 or a data processing device and advantageously also a regulation device 103, captured temperature data, advantageously said temperature or thermal image of the layer 1, can be stored and transferred to the processing device 20 or this can be controlled accordingly.
An apparatus 100 can accordingly be configured to control the processing device 20 and can also comprise said computer program means (see reference sign CPP further below), the temperature capture device 101, the computer 102 and, for example, the regulation device 103. Accordingly, the apparatus 100 can be coupled or connected to the processing device 20.
In the embodiment shown in
The “region of interest”, which is shown by way of example on the left in
According to the present invention, temperature data or temperature values T of the layer 1 are correspondingly captured and/or stored in a spatially resolved manner by the temperature capture device 101.
The region of interest can be determined, for example, by (predefined) positions or position data of the processing device, more precisely of the induction coil 104 or its “eye”.
Instead of, for example, carrying a pyrometer for capturing the temperature of or processing the layer 1 to a multiplicity of positions (see
Corresponding temperature values or pixels P, in particular, are captured on the basis of the temperature image captured by the temperature capture device. This can be done by means of calibration or corresponding conversion of image data into temperature values. The captured temperature values T in the region of interest are now classified, advantageously automatically or in a computer-implemented manner, based on the required regulation quality and efficiency.
For expedient temperature regulation in the context described, it is furthermore most expedient to provide a reliable value or mean value for a maximum temperature within the region of interest. Therefore, in one advantageous configuration of the present invention (see also
For the sake of simplicity, only one coil 104, which can heat a region ROI to be selected in a predefined manner, is identified in
The processing device 20 is also advantageously configured to be moved, through its movability, over any positions above the powder bed or the layer surface in such a way that both an already solidified component layer (see layer 1) and a layer of newly applied base material or powder (see layer 2) can be heated. In contrast to the solid component structure, however, heating of the powder (see on the left in
Temperature values T, which advantageously correspond to captured temperatures or temperature values from the region of interest (see
In particular, six temperature classes are classified or divided by way of example and in a simplified manner; a first temperature class between T1 and T2, a second temperature class between T2 and T3, a third temperature class between T3 and T4, a fourth temperature class between T4 and T5, a fifth temperature class between T5 and T6 and a sixth temperature class between T6 and T7. It is also shown by way of example that the class widths (compare, for example, b1 for the first temperature class and b2 for the second temperature class) of the second, third, fourth and fifth temperature classes are the same and are half as large as the class widths of the first and sixth temperature classes.
In the present case, the different class widths can be, for example, only one or more tenths of a degree Celsius.
The area of the rectangles (compare, for example, a1 for the first temperature class and a2 for the second temperature class), which respectively denotes the relative or absolute class frequency, corresponds to the product of the respective class width bn and the frequency density ρ. Correspondingly, the frequency density ρ is plotted on the ordinate of the histogram.
The class frequency reflects either an absolute or a relative value. The absolute value corresponds to the number of values that belong to a class. The relative value, on the other hand, expresses what percentage of the values belong to a class.
As indicated above with reference to the description of
The captured temperature data can be divided or classified, for example, by means of machine optimization methods, for example representing or comprising artificial neural networks or genetic or evolutionary algorithms.
According to the present invention, a mean value, advantageously the arithmetic mean value, of the classified temperature values is now formed. This value can then be used to subsequently control or regulate the processing device 20 as an actual or input value, for example in order to process the layer 1 (see
The noise can be reduced by transmitting or capturing an item of information multiple times. Since noise occurs stochastically, the standard deviation of the noise signal, for example, also increases only by the factor √{square root over (n)} when n transmissions are added, whereas the signal increases by the factor n. The signal-to-noise ratio related to the signal amplitude increases by √{square root over (n)}.
The mean value can accordingly denote an actual value for a PID regulator which can function as a regulation device 103. The regulation device, for example having a PI, PD or PID regulator, can be configured using software and hardware, for example, and can be executed on the computer 102 or another programmable device, for example.
For example, a heat treatment tailored to the alloy of the component may be necessary or advantageous, for example, in order to relieve tension in the component, avoid or prevent hot cracks or to prevent large process-inherent temperature gradients which in turn prevent cracks, chemical imbalances or, in principle, weldability of the base material.
The corresponding processing regions (compare ROI at positions P1, P2 and P3 in
Typically, after processing a first position P1, the coil 104 or the processing device 20 is moved to a subsequent second position P2 and/or to a subsequent third position P3, which then indicates a not yet heated or cold point, and can be processed, for example, in a corresponding ROI of the position. Instead of three positions and/or ROIs, as indicated in
The temperature capture device 101, like the processing device 20, can be concomitantly moved from one position to the next in this case. However, this is not absolutely necessary. With suitable positioning, only a single temperature image of the layer can also be sufficient to successfully carry out the processing on the basis of the captured temperature values. The region of interest can then be shifted from a first position to a further or second position, for example simultaneously with the movement of the processing device 20, using data, software or program technology, for example, during the additive manufacturing of the component. In other words, only a corresponding measurement region can accordingly be shifted (virtually).
According to the present invention, the temperature data, as described above, are stored and/or captured at different positions of the additively constructed layer 1, advantageously in the determined regions of interest ROI (compare method steps a) and b) further below); rather than, for instance, within the entire recorded temperature image. Furthermore, the temperature values can be stored and/or captured during the processing of the layer, for example along the positions P1 to P3 as a function of the position or per ROI.
The regulation of the temperature or the processing of the layer 1 with the processing device 20 can still be carried out quasi-continuously in the present case. In particular, a dense sequence of images from the infrared camera, which can capture for example data or images at 50 Hz, can be used for quasi-continuous or time-dependent regulation; and this per region of interest and for each additively constructed layer or layer to be additively constructed.
The invention is not restricted by the description based on the exemplary embodiments to these exemplary embodiments, but rather encompasses any new feature and any combination of features. This includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18207810.5 | Nov 2018 | EP | regional |
This application is the US National Stage of International Application No. PCT/EP2019/079341 filed 28 Oct. 2019, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP18207810 filed 22 Nov. 2018. All of the applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/079341 | 10/28/2019 | WO | 00 |
