EP4284579A1 - Method for the additive manufacturing of components with locally selective temperature control - Google Patents
Method for the additive manufacturing of components with locally selective temperature controlInfo
- Publication number
- EP4284579A1 EP4284579A1 EP21830598.5A EP21830598A EP4284579A1 EP 4284579 A1 EP4284579 A1 EP 4284579A1 EP 21830598 A EP21830598 A EP 21830598A EP 4284579 A1 EP4284579 A1 EP 4284579A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- component
- layer
- temperature
- cooling
- temperature control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
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- 238000009529 body temperature measurement Methods 0.000 claims abstract description 13
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/50—Treatment of workpieces or articles during build-up, e.g. treatments applied to fused layers during build-up
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/10—Auxiliary heating means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/20—Cooling means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/90—Means for process control, e.g. cameras or sensors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/03—Observing, e.g. monitoring, the workpiece
- B23K26/034—Observing the temperature of the workpiece
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/08—Devices involving relative movement between laser beam and workpiece
- B23K26/083—Devices involving movement of the workpiece in at least one axial direction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/34—Laser welding for purposes other than joining
- B23K26/342—Build-up welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
- B23K26/703—Cooling arrangements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K37/00—Auxiliary devices or processes, not specially adapted for a procedure covered by only one of the other main groups of this subclass
- B23K37/003—Cooling means for welding or cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/04—Welding for other purposes than joining, e.g. built-up welding
- B23K9/042—Built-up welding on planar surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/095—Monitoring or automatic control of welding parameters
- B23K9/0956—Monitoring or automatic control of welding parameters using sensing means, e.g. optical
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/173—Arc welding or cutting making use of shielding gas and of a consumable electrode
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
Definitions
- the invention is based on a method for the generative manufacture of components, the method having the melting of a metallic additive along a trajectory on a substrate, with a component being built up in layers on the substrate.
- a method for the generative manufacture of components the method having the melting of a metallic additive along a trajectory on a substrate, with a component being built up in layers on the substrate.
- Such a method is known, for example, from WO 2018/228919 Ai. Similar methods are also described in DE 102017 216 704 Ai, DE 10 2014203 711 Ai and DE 10 2015 108 131 Ai.
- the measuring device for determining the tensile strength has an energy source for melting a metallic filler material, a temperature measuring unit for measuring a temperature-time curve of the melted filler material and an evaluation unit for determining the transformation start temperature for a ferritic or bainitic microstructure transformation of the filler material and for applying a regression line for the determination the tensile strength of the welded filler metal.
- EP 3 359320 Bi describes another method for additive manufacturing, in which a cooling fluid is provided adjacent to the generating point of action on the surface of the substrate via a nozzle, the fluid supply having a plurality of nozzles which are arranged in a ring around a material supply, wherein the fluid volume flow of each nozzle can be controlled individually.
- EP 3581380 A2 also describes a method for process monitoring in additive manufacturing in order to improve the predictability of the material properties of a built-up component.
- WO 2017/059842 Ai describes a processing module for a device for additive manufacturing, wherein the processing module has a material feed device and a protective gas feed device, which has one or more outflow openings arranged in a ring around the material feed device, via which a cooling fluid is applied directly next to the generating site to a surface of the Shaped body is applied.
- Wire Arc Additive Manufacturing is a high-performance process for the additive manufacturing of metallic components that enables the realization of high deposition rates.
- the high production speed is accompanied by a high level of heat input into the component.
- the high heat input can result in a significant deterioration in the mechanical-technological material properties. Therefore, precise process monitoring to ensure the component properties is of particular importance.
- known approaches are aimed at monitoring the temperature using a thermal camera or a pyrometer, they have insufficient accuracy, since only global temperatures of the built-up component are recorded. Thermal cameras are usually used here, which provide temperature information whose quality is not sufficient to make a statement about the mechanical properties.
- the temperature control of the built-up component in additive manufacturing is a key factor in increasing profitability by reducing production times.
- the focus here is on dissipating excess heat from the component.
- different temperature gradients form across the workpiece, which lead to inhomogeneous material properties across the component volume.
- the causes lie in accumulations of material, but also in path planning or in varying boundary conditions for heat dissipation, for example as a result of inhomogeneous cooling by cooling media or cooling plates. It is therefore the object of the invention to propose a method for additive manufacturing which, with high application rates and thus short process times, also allows preferred material properties to be maintained, preferably over the entire component volume.
- the component is temperature-controlled in a location-selective manner by a directed fluid jet, either during the build-up of a layer or subsequent to the build-up of a first layer and before the build-up of a further, second layer on the first layer.
- the temperature control should take place depending either on at least one spatially resolved temperature measurement value recorded with a sensor at a specific location on the layer or on a cooling curve which is derived from a plurality of temperature measurement values recorded one after the other at the location. Tempering may include heating and cooling.
- the component is exposed to an aerosol jet in a location-selective manner, which has a material component that undergoes an endothermic phase transition when the aerosol jet hits the component.
- the method can be used in particular within the scope of arc-based additive manufacturing, for example using a Wire Arc Additive Manufacturing method (WAAM).
- WAAM Wire Arc Additive Manufacturing method
- building up the first layer and/or building up the further layer on the first layer can include carrying out a WAAM method.
- the location-selective temperature control can be provided with the aid of at least one movable temperature control nozzle or with the aid of a multiplicity of temperature control nozzles which are aligned differently in relation to the component to be temperature-controlled and which can be selectively controlled.
- the tempering can, for example, include heating the component if, due to a comparatively large outer surface of the component in relation to the volume of the component, the heat dissipation to the ambient air is higher than is desired for cooling to achieve desired material properties. Where and at what intensity the component, in particular the built-up layer, is cooled or heated can be determined based on a wide variety of parameters or using different temperature control models can be achieved.
- the spatially resolved temperature determination of the component or of the last or currently built up layer can be carried out using a thermal imaging camera or a pyrometer.
- the need for temperature control can also be influenced by appropriate path planning of the energy source. Material accumulations can be determined with the aid of path planning. Finally, a stored empirical expert model can be used to determine the need for temperature control. As is fundamentally known from the state of the art, time parameters such as the t8/5 time can be used to maintain the material properties. With the help of the method described above, the material properties of the built-up component can be controlled in a targeted manner and material failure can be prevented.
- the use of tempering fluids allows in-situ cooling at a safe distance from the additive tool during the manufacturing process. The temperature control process is therefore more effective and therefore more resource-saving, especially with regard to the temperature control medium used.
- the tempering can include the atomization of a cooling medium, for example to generate an aerosol.
- the atomized temperature control medium can be subjected to focusing in order to achieve further precision of the location on the component or on the built-up layer that is acted upon by the temperature control medium.
- the tempering medium can be passed through a nozzle, which has a groove on its inner circumference that extends spirally around the passage direction of the nozzle. When the temperature control medium is guided through the nozzle, the temperature control medium only experiences a twist about its propagation direction on its outer circumference, which counteracts a divergence of the fluid jet or leads to a compaction of the fluid jet.
- the at least one spatially resolved measured temperature value and/or the cooling curve can be measured simultaneously or sequentially at different locations in the layer, and a temperature distribution and/or a temperature gradient along a surface of the layer can be determined from the measured temperature values recorded or from the cooling curves.
- a reliable local prediction of the tensile strength can be achieved even with the additive processing of low-alloy steels.
- a volume flow of the fluid jet can be adjusted along a surface of the layer as a function of the spatially resolved measured temperature value, or of the cooling curve, or of a temperature gradient derived therefrom.
- further temperature measurement values and/or a cooling curve at the temperature-controlled location of the layer can be recorded continuously or periodically.
- a cooling or heating capacity of the fluid jet in relation to the layer can be readjusted in situ by varying a volume flow of the fluid jet as a function of the further measured temperature values and/or the cooling curve.
- the at least one measured temperature value and/or the cooling curve can be determined at several different locations on the layer.
- a heat flow within the layer between the locations can be inferred from a difference in the measured temperature values of adjacent locations on the layer and/or from the difference in the cooling curve of adjacent locations on the layer.
- a cooling or heating capacity of the fluid jet can also be selected so that the heat flow within the layer or component is minimized.
- the temperature control can include the location-selective impingement of a fluid jet on the component.
- the temperature control can preferably also include the atomization of a liquid or solid temperature control medium, with an aerosol containing the temperature control medium preferably being formed.
- the component or the last layer built up can be cooled or heated by aerosols and/or a jet of liquid, gas or solids.
- an endothermic phase transition of suspended particles in the fluid for example in aerosol particles of the aerosol, can take place, for example from liquid to gaseous.
- heat transfer can take place by conducting heat from the component into aerosol particles.
- the temperature control ie the application of the directed fluid jet to the component or the layer, can take place independently of a movement of the additive tool or the energy source during the construction process, whereby an economic advantage is achieved.
- the state of Technology in particular global cooling provided by gases or immersive liquid cooling of the workpiece.
- tempering can include the location-selective impingement of the component with an aerosol, liquid, gas or solid jet that has a material component that undergoes an endothermic phase transition and/or is heated or cooled by thermal conduction when it is impinged on the component hits.
- the tempering can include aligning at least one tempering medium outlet, preferably a nozzle, of a tempering medium source to a section of the component that is to be cooled or heated.
- the tempering medium source can be moved relative to and at a distance from the component and independently of an energy source for melting the metallic filler material and/or independently of the sensor.
- the tempering can include the selective activation of one or more of a plurality of tempering medium outlets of a tempering medium source, for which purpose the plurality of tempering medium outlets are arranged statically around the component and face the component.
- a cooling capacity for cooling the location on the layer at which the temperature measurement value is recorded with the sensor in a spatially resolved manner, or a section of the component encompassing the location, or a heating capacity for heating the location or section of the component can be achieved by varying the temperature control medium volume flow, which Component applied, take place.
- the temperature control medium volume flow can be set in such a way that the cooling curve derived from the spatially resolved temperature values is approximated to a desired cooling curve.
- the substrate or the component can be moved along the trajectory relative to a fixed energy source for melting the filler material.
- a fixed energy source and preferably also a fixed sensor, for example a pyrometer
- the kinematic component movement can be used to obtain a fixed spatial relationship between the trajectory and the location on the layer at which the spatially resolved temperature measurement is carried out.
- the substrate or the component is moved on a complex trajectory under the energy source.
- the sensor for example a pyrometer
- a spatially resolved gradient map can be created and from this the mechanical properties of the component produced can be determined in a spatially resolved manner. It is thus proposed to determine the tensile strength distribution of a component produced over its entire volume during its production, i.e. in-situ, for the purpose of quality assurance and the estimation of the structural properties.
- a spatially resolved gradient map can be generated by linking the movement information of the component in relation to the energy source with the determined cooling curves, and from this the mechanical properties of the component can be derived locally resolved.
- the substrate can also be moved along the trajectory relative to at least one stationary sensor for the spatially resolved detection of at least one property, preferably a temperature, of a layer of the component that was last built up.
- the sensor may be maintained at a fixed relative disposition to the energy source, preferably at a fixed, acute angle and/or to the energy source, with the substrate relative to the energy source and the sensor while maintaining the fixed relative disposition between the energy source and the Sensor is moved along the trajectory.
- the method can also include the selective detection of at least one measured value, for example the temperature measured value, at at least one measuring point on the last layer built up with the sensor.
- the same relative arrangement between the respective measuring point on the layer and a respective molten pool of the additional material for the structure of the layer is preferably maintained for several pairs of measured value and measuring points.
- the sensor can be fixed in relation to an energy source and can preferably have the same feed along the trajectory as the energy source.
- a large number of measured values can be recorded at a corresponding large number of measuring points on the built-up component, with at least one measured value preferably being recorded for each measuring point.
- a spatially resolved measured value curve along the trajectory can be generated from the large number of measured values, for example by means of a regression analysis.
- the temperature of the built-up component can be recorded at at least one measuring point on the built-up component.
- a temperature gradient along the trajectory can be determined from the temperature at the measuring point, a distance from the measuring point to a melt pool along the trajectory and a feed rate of the energy source along the trajectory.
- a sensor for the directed, non-contact temperature measurement for example a pyrometer, can be used for the sensor when determining the measured value, with which a spatially resolved cooling curve of the last built-up layer of the component is determined.
- the method can also include manipulating the trajectory and/or at least one process parameter for melting the additional material and/or for building up the component in layers.
- the manipulation can be set up to match or further approximate the determined cooling curve to a preferred cooling curve in order to set a preferred material property.
- a spatially resolved cooling curve can be determined at a large number of measurement points on the last layer built up and/or on a plurality of layers built up one after the other.
- a spatially resolved cooling gradient map of the layer or component can be determined from the determined spatially resolved cooling curves and at least one mechanical property of the last layer or component built up can be determined in a locally resolved manner.
- FIG. 1 shows a schematic representation of a method according to the invention according to a first embodiment
- FIG. 2 shows a schematic representation of a method according to the invention according to a second embodiment
- FIG. 3 shows a detailed view of an exemplary device for carrying out a method according to the invention
- FIG. 4 shows a measuring point grid of a sensor for the location-selective detection of measured temperature values
- FIG. 5 is a cooling gradient map derived from temperature readings taken along a grid of FIG. 4;
- FIG. 6 shows a resulting deformation of an additively manufactured component derived using the cooling gradient map according to FIG.
- FIG. 1 illustrates in a schematic representation a first embodiment of a method according to the invention for the additive manufacturing of components.
- an energy source 10 a molten bath of an additional material 1 is produced locally on a substrate 3 or on a material layer previously applied to the substrate.
- the energy source 10 and an additional material feed (not shown) are moved along the trajectory 2 in order to build up the component in layers, for example in accordance with a previously generated CAD design.
- the energy source 10 and the filler material supply (not shown) can also be arranged statically and with a defined alignment to one another and the component, and therefore the substrate 3, can be moved relative to the energy source 10 and the filler material supply.
- the substrate 3 or the component 4 can be moved on a complex trajectory 2 under the energy source 10 .
- a sensor 5 for example a pyrometer, to detect spatially resolved cooling curves under constant boundary conditions.
- the entire construction process is recorded with a sensor 5, which is embodied in the present case as a pyrometer or a thermal imaging camera.
- the pyrometer or the thermal imaging camera is set up to spatially resolved the To detect the temperature of the component 4, but at least the last built-up layer of the component 4, in order to enable a location-selective temperature control of the layer or of the component 3 depending on the detected temperature distribution or on location-selectively detected cooling curves.
- the temperature control in particular the cooling of the component or the layer applied last, can be set up to approximate the actual cooling curve of the layer or of the component 3 detected with the aid of the sensor 5 to a preferred cooling curve in relation to the desired material properties.
- the aim can be to bring the cooling curves closer together over the entire component, so that homogeneous material properties are achieved over the entire body of the component.
- the natural cooling through free convection and thermal radiation to the ambient air can vary over the volume of the component, so that the cooling curves can be brought closer together over the entire body of the component through targeted temperature control intervention.
- At least one temperature control medium source 9 is provided for temperature control of the layer or of the component 3, which can apply a directed fluid jet 6 to a point on the component 3 that requires temperature control, for example via a temperature control medium outlet 8, such as a nozzle.
- the directed fluid jet 6 can have an aerosol, for example, as the temperature control medium 7 .
- Alternative tempering media can include oils or oil emulsions to adjust the boiling point of the tempering medium.
- the oils or oil emulsions can protect the component 4 against corrosion.
- the cooling medium can contain a potassium solution, for example, so that the temperature control medium can continue to be used to stabilize the arc in addition to its temperature control property.
- flux as a cooling medium, oxides on the layer can be removed or the penetration can be changed.
- the use of other chemical additives is conceivable, which lead to a change in the alloy composition when overwelding.
- the aim can be to increase the vaporization temperature so that the liquid contained in the aerosol comes closer to the process zone and thus achieves more effective heat transfer from the component to the aerosol via the vaporization enthalpy becomes.
- oil-water Emulsions are used as liquids of the aerosol. Due to their heat capacity and thermal conductivity, the use of gases can also be advantageous if temperature control, in particular cooling, is to be carried out in the immediate vicinity of the molten bath. To avoid pores, the use of inert gases has proven to be particularly useful. Cooling medium evaporating during temperature control can be taken up with the aid of a temperature control medium recovery system 11 and, after condensation, can be recirculated to the temperature control medium sources 9 for reuse.
- the substrate 3 is moved relative to the energy source 10 along the trajectory 2, while the energy source 10 is stationary.
- a fixed relationship between the welding trajectory 2 and a temperature measuring point of the sensor 5 on the component 3 can be achieved.
- cooling curves can be measured under constant boundary conditions by means of the sensor 5, which can be a pyrometer, for example.
- a machine learning algorithm based on a pre-trained neural network can be used to determine a cooling curve for a materially relevant area of the component 3 from the recorded information.
- a spatially resolved gradient map can be generated and from this the mechanical properties of the component can be derived in a locally resolved manner.
- FIG. 2 shows a further embodiment of a method according to the invention, in which, in contrast to the embodiment according to FIG.
- provision can be made on the one hand for the temperature control medium sources 9 to be controlled selectively and on the other hand for the component 3 to be moved, for example by an articulated-arm robot, in relation to at least one of the temperature control medium sources 9 in such a way that the outlet 8 of the temperature control medium source 9 is located exactly at a point in the last built-up layer that requires temperature control or of the component 3 is facing, so that a highly precise location-selective impingement of the component or the layer with the directed fluid jet 6 is possible.
- FIG. 3 shows a detailed view of an exemplary structure for carrying out the method according to the invention.
- a tempering medium source 9 is arranged in the welding direction of an energy source 10, for example an arc or a plasma arc welding torch.
- the tempering medium source 9 faces the substrate 3 at an acute angle to the energy source 10 and is aligned opposite to the welding direction.
- the energy source 10 and the tempering medium source 9 are arranged in a rigid relationship to one another, in particular at a fixed angle and at a fixed distance from one another.
- the energy source 10 and the temperature control medium source 9 can be positioned fixed to one another on an end effector of an articulated arm robot.
- the last applied layer or the component is acted upon by the tempering medium emerging from the tempering medium source 9 at a given feed rate of the arrangement of the energy source 10 and the tempering medium source 9 in the welding direction at a constant time interval, so that the influencing of the temperature of the melt or the solidifying material can be adjusted in a process-reliable manner by applying the temperature control medium source 9 .
- This enables the precise influencing of the cooling curve of the applied material and thus the material properties of the material.
- a measuring grid which can be that of a pyrometer, for example, which can be used as a sensor for the spatially resolved temperature measurement on the surface of the applied component, in particular a layer applied last.
- a temperature measurement value can be recorded continuously or periodically along the grid points, so that at a given location on the component or the last applied layer, a cooling curve can be determined from a plurality of temperature values recorded in chronological succession at a respective grid point, from which conclusions can be drawn can be derived from a material property of the constructed material.
- stresses within the material can also be derived using a cooling gradient map according to FIG. 5 determined from the recorded cooling curves.
- mechanical stressing of the component can be determined on the basis of the deviations in the cooling gradients resulting from the deviations in the cooling gradient map due to the stronger cooling in the surface area of the component compared to the areas further inside the component.
- Tensile strength values distributed over the volume of the component can also be determined from the cooling gradient map.
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Abstract
Description
VERFAHREN FÜR DIE GENERATIVE FERTIGUNG VON BAUTEILEN MIT ORTSSELEKTIVER TEMPERIERUNG PROCESSES FOR THE ADDITIONAL MANUFACTURE OF COMPONENTS WITH LOCATION-SELECTIVE TEMPERATURE CONTROL
Die Erfindung geht aus von einem Verfahren für die generative Fertigung von Bauteilen, wobei das Verfahren das Aufschmelzen eines metallischen Zusatzwerkstoffs entlang einer Trajektorie auf einem Substrat aufweist, wobei ein Bauteil schichtweise auf dem Substrat aufgebaut wird. Ein derartiges Verfahren ist beispielsweise aus der WO 2018/228919 Ai bekannt. Ähnliche Verfahren beschreiben auch die DE 102017 216 704 Ai, DE 10 2014203 711 Ai und die DE 10 2015 108 131 Ai. The invention is based on a method for the generative manufacture of components, the method having the melting of a metallic additive along a trajectory on a substrate, with a component being built up in layers on the substrate. Such a method is known, for example, from WO 2018/228919 Ai. Similar methods are also described in DE 102017 216 704 Ai, DE 10 2014203 711 Ai and DE 10 2015 108 131 Ai.
Die DE 10 2015 122889 B3 beschreibt ein Verfahren und eine Messanordnung für die zerstörungsfreie Abschätzung der Zugfestigkeit eines geschweißten Werkstoffs, der zumindest ein ferritisches Gefüge aufweist. Die Messvorrichtung zum Bestimmen der Zugfestigkeit weist eine Energiequelle zum Aufschmelzen eines metallischen Zusatzwerkstoffs, eine Temperaturmesseinheit zum Messen eines Temperatur-Zeit- Verlaufs des aufgeschmolzenen Zusatzwerkstoffs und eine Auswerteinheit zum Bestimmen der Umwandlungsstarttemperatur für eine ferritische oder bainitische Gefügeumwandlung des Zusatzwerkstoffs sowie zum Anwenden einer Regressionsgeraden zum Bestimmen der Zugfestigkeit des aufgeschweißten Zusatzwerkstoffs auf. DE 10 2015 122889 B3 describes a method and a measuring arrangement for non-destructive estimation of the tensile strength of a welded material that has at least one ferritic structure. The measuring device for determining the tensile strength has an energy source for melting a metallic filler material, a temperature measuring unit for measuring a temperature-time curve of the melted filler material and an evaluation unit for determining the transformation start temperature for a ferritic or bainitic microstructure transformation of the filler material and for applying a regression line for the determination the tensile strength of the welded filler metal.
Aus der DE 10 2015 108 131 Ai ist ein weiteres Verfahren für die additive Fertigung bekannt, bei dem der Schweißprozess mittels Sensoren überwacht wird, wobei mittels erfasster Sensordaten die Schweißparameter des Schweißprozesses derart beeinflusst werden sollen, dass die Wärmeabfuhr aus einem aufgeschmolzenen Zusatzwerkstoff an einem Bearbeitungspunkt konstant gehalten wird, wodurch bei verkürzten Fertigungszeiten die Gefügestruktur des Formkörpers verbessert und Eigenspannungen reduziert werden sollen. Another method for additive manufacturing is known from DE 10 2015 108 131 Ai, in which the welding process is monitored by means of sensors, with the welding parameters of the welding process being influenced by means of recorded sensor data in such a way that the heat dissipation from a melted filler material at a processing point is kept constant, whereby the microstructure of the molded body is improved and internal stresses are to be reduced with reduced production times.
Die EP 3 359320 Bi beschreibt ein weiteres Verfahren für die additive Fertigung, bei dem ein Kühlfluid benachbart zu dem Generierwirkort auf der Oberfläche des Substrates über eine Düse bereitgestellt wird, wobei die Fluidzuführung eine Mehrzahl Düsen aufweist, die ringförmig um eine Werkstoffzuführung angeordnet sind, wobei der Fluidvolumenstrom jeder Düse einzeln ansteuerbar ist. EP 3 359320 Bi describes another method for additive manufacturing, in which a cooling fluid is provided adjacent to the generating point of action on the surface of the substrate via a nozzle, the fluid supply having a plurality of nozzles which are arranged in a ring around a material supply, wherein the fluid volume flow of each nozzle can be controlled individually.
Ein weiteres additives Fertigungsverfahren ist aus der EP 3 646 967 Ai bekannt, bei dem ein Kühlfluidvolumenstrom, mit dem ein Substrat zumindest teilweise beaufschlagt wird, derart nachgeregelt wird, dass eine zur Erreichung bevorzugter Materialeigenschaften eines aufgebauten Bauteils erforderliche Wärmeableitung eines Zusatzwerkstoffs erreicht wird. Another additive manufacturing method is known from EP 3 646 967 Ai, in which a cooling fluid volume flow, with which a substrate is at least partially applied, is readjusted in such a way that a preferred Material properties of a built-up component required heat dissipation of an additional material is achieved.
Auch die EP 3581380 Ä2 beschreibt ein Verfahren für die Prozessüberwachung bei der additiven Fertigung, um die Vorhersagbarkeit der Materialeigenschaften eines aufgebauten Bauteils zu verbessern. EP 3581380 A2 also describes a method for process monitoring in additive manufacturing in order to improve the predictability of the material properties of a built-up component.
Die WO 2017/059842 Ai beschreibt ein Bearbeitungsmodul für eine Vorrichtung zur additiven Fertigung, wobei das Bearbeitungsmodul eine Werkstoffzuführungseinrichtung sowie eine Schutzgaszuführungseinrichtung aufweist, die eine oder mehrere ringförmig um die Werkstoffzuführungseinrichtung angeordnete Auströmöffnungen aufweist, über die ein Kühlfluid unmittelbar neben dem Generierwirkort auf eine Oberfläche des Formkörpers aufgebracht wird. WO 2017/059842 Ai describes a processing module for a device for additive manufacturing, wherein the processing module has a material feed device and a protective gas feed device, which has one or more outflow openings arranged in a ring around the material feed device, via which a cooling fluid is applied directly next to the generating site to a surface of the Shaped body is applied.
Das Wire Arc Additive Manufacturing ist ein Hochleistungsverfahren zur additiven Fertigung von metallischen Bauteilen, das die Realisierung hoher Auftragraten ermöglicht. Mit der hohen Fertigungsgeschwindigkeit geht eine starke Wärmeeinbringung in das Bauteil einher. Je nach verarbeitetem Werkstoff kann die hohr Wärmeeinbringung eine deutliche Verschlechterung der mechanischtechnologischen Werkstoffeigenschaften mit sich bringen. Daher ist eine präzise Prozessüberwachung zur Sicherung der Bauteileigenschaften von besonderer Bedeutung. Bekannte Ansätze zielen zwar auf die Temperaturüberwachung mittels einer Thermokamera oder eines Pyrometers ab, weisen jedoch eine nur unzureichende Genauigkeit auf, da ausschließlich globale Temperaturen des aufgebauten Bauteils erfasst werden. Hierbei werden üblicherweise Thermokameras verwendet, die Temperaturinformationen liefern, deren Qualität nicht ausreicht, um eine Aussage über die mechanischen Eigenschaften zu treffen. Wire Arc Additive Manufacturing is a high-performance process for the additive manufacturing of metallic components that enables the realization of high deposition rates. The high production speed is accompanied by a high level of heat input into the component. Depending on the material being processed, the high heat input can result in a significant deterioration in the mechanical-technological material properties. Therefore, precise process monitoring to ensure the component properties is of particular importance. Although known approaches are aimed at monitoring the temperature using a thermal camera or a pyrometer, they have insufficient accuracy, since only global temperatures of the built-up component are recorded. Thermal cameras are usually used here, which provide temperature information whose quality is not sufficient to make a statement about the mechanical properties.
Daher ist die Temperierung des aufgebauten Bauteils bei der additiven Fertigung ein wesentlicher Faktor für die Erhöhung der Wirtschaftlichkeit durch Reduktion der Produktionszeiten. Dabei steht die Ableitung überschüssiger Wärme aus dem Bauteil im Vordergrund. Darüber hinaus bilden sich über das Werkstück unterschiedliche Temperaturgradienten aus, die zu inhomogenen Werkstoffeigenschaften über das Bauteilvolumen führen. Die Ursachen liegen in Materialanhäufungen, aber auch in der Pfadplanung oder in variierenden Randbedingungen für die Wärmeableitung, beispielsweise in Folge einer inhomogenen Kühlung durch Kühlmedien oder Kühlplatten. Es ist daher die Aufgabe der Erfindung, ein Verfahren für die additive Fertigung vorzuschlagen, welches bei hohen Auftragraten und damit kurzen Prozesszeiten ebenso die Einhaltung bevorzugter Materialeigenschaften vorzugsweise über das gesamte Bauteilvolumen erlaubt. Therefore, the temperature control of the built-up component in additive manufacturing is a key factor in increasing profitability by reducing production times. The focus here is on dissipating excess heat from the component. In addition, different temperature gradients form across the workpiece, which lead to inhomogeneous material properties across the component volume. The causes lie in accumulations of material, but also in path planning or in varying boundary conditions for heat dissipation, for example as a result of inhomogeneous cooling by cooling media or cooling plates. It is therefore the object of the invention to propose a method for additive manufacturing which, with high application rates and thus short process times, also allows preferred material properties to be maintained, preferably over the entire component volume.
Diese Aufgabe wird durch ein Verfahren mit den Merkmalen des Anspruchs i gelöst. Die abhängigen Ansprüche betreffen jeweils vorteilhafte Ausführungsformen der Erfindung. This object is achieved by a method having the features of claim i. The dependent claims each relate to advantageous embodiments of the invention.
Demgemäß ist vorgesehen, dass das Bauteil durch einen gerichteten Fluidstrahl ortsselektiv temperiert wird, entweder während des Aufbaus einer Schicht oder anschließend an den Aufbau einer ersten Schicht und vor dem Aufbau einer weiteren, zweiten Schicht auf der ersten Schicht. Die Temperierung soll abhängig entweder von mindestens einem an einem bestimmten Ort auf der Schicht mit einem Sensor erfassten ortsaufgelösten Temperaturmesswert oder von einer Abkühlkurve erfolgen, die aus einer Mehrzahl nacheinander an dem Ort erfasster Temperaturmesswerte abgeleitet wird. Das Temperieren kann das Erwärmen und das Kühlen aufweisen. Das Bauteil wird mit einem Aerosolstrahl ortsselektiv beaufschlagt, der einen Materialbestandteil aufweist, der einen endothermen Phasenübergang erfährt, wenn der Aerosolstrahl auf das Bauteil trifft. Accordingly, it is provided that the component is temperature-controlled in a location-selective manner by a directed fluid jet, either during the build-up of a layer or subsequent to the build-up of a first layer and before the build-up of a further, second layer on the first layer. The temperature control should take place depending either on at least one spatially resolved temperature measurement value recorded with a sensor at a specific location on the layer or on a cooling curve which is derived from a plurality of temperature measurement values recorded one after the other at the location. Tempering may include heating and cooling. The component is exposed to an aerosol jet in a location-selective manner, which has a material component that undergoes an endothermic phase transition when the aerosol jet hits the component.
Das Verfahren kann insbesondere im Rahmen einer lichtbogenbasierten additiven Fertigung angewendet werden, beispielsweise in Anwendung eines Wire Arc Additive Manufacturing-Verfahrens (WAAM). Insbesondere kann das Aufbauen der ersten Schicht und/ oder das Aufbauen der weiteren Schicht auf der ersten Schicht das Durchführen eines WAAM-Verfahrens aufweisen. The method can be used in particular within the scope of arc-based additive manufacturing, for example using a Wire Arc Additive Manufacturing method (WAAM). In particular, building up the first layer and/or building up the further layer on the first layer can include carrying out a WAAM method.
Die ortsselektive Temperierung kann mit Hilfe mindestens einer beweglichen Temperierdüse oder mit Hilfe einer Vielzahl unterschiedlich in Bezug auf das zu temperierende Bauteil ausgerichteter Temperierdüsen, welche selektiv angesteuert werden können, bereitgestellt sein. Das Temperieren kann beispielweise dann das Erwärmen des Bauteils umfassen, wenn aufgrund einer vergleichsweise hohen äußeren Oberfläche des Bauteils in Bezug auf das Volumen des Bauteils die Wärmeableitung an die Umgebungsluft höher ist, als dies für die Abkühlung zur Erzielung gewünschter Materialeigenschaften gewünscht ist. Wo und in welcher Intensität das Bauteil, insbesondere die aufgebaute Schicht gekühlt beziehungsweise erwärmt wird, kann anhand unterschiedlichster Parameter beziehungsweise unter Verwendung unterschiedlichster Temperiermodelle erreicht werden. Dabei kann die ortsaufgelöste Temperaturermittlung des Bauteils bzw. der zuletzt oder aktuell aufgebauten Schicht mit Hilfe einer Wärmebildkamera oder eines Pyrometers erfolgen. The location-selective temperature control can be provided with the aid of at least one movable temperature control nozzle or with the aid of a multiplicity of temperature control nozzles which are aligned differently in relation to the component to be temperature-controlled and which can be selectively controlled. The tempering can, for example, include heating the component if, due to a comparatively large outer surface of the component in relation to the volume of the component, the heat dissipation to the ambient air is higher than is desired for cooling to achieve desired material properties. Where and at what intensity the component, in particular the built-up layer, is cooled or heated can be determined based on a wide variety of parameters or using different temperature control models can be achieved. The spatially resolved temperature determination of the component or of the last or currently built up layer can be carried out using a thermal imaging camera or a pyrometer.
Der Temperierbedarf kann auch durch eine geeignete Pfadplanung der Energiequelle beeinflusst werden. Mit Hilfe der Pfadplanung kann auf Materialanhäufungen geschlossen werden. Schließlich kann ein hinterlegtes empirisches Expertenmodell dazu verwendet werden, den Temperierbedarf zu ermitteln. Wie es grundsätzlich aus dem Stand der Technik bekannt ist, kann zur Einhaltung der Werkstoffeigenschaften auf zeitliche Kenngrößen wie die t8/5-Zeit zurückgegriffen werden. Mit Hilfe des zuvor beschriebenen Verfahrens können die Werkstoffeigenschaften des aufgebauten Bauteils gezielt gesteuert und Materialversagen verhindert werden. Die Verwendung von Temperierfluiden erlaubt es, in einem sicheren Abstand zum additiven Werkzeug bereits während des Fertigungsprozesses in-situ zu kühlen. Der Temperiervorgang ist daher effektiver und damit ressourcensparender, insbesondere in Bezug auf das verbrauchte Temperiermedium. The need for temperature control can also be influenced by appropriate path planning of the energy source. Material accumulations can be determined with the aid of path planning. Finally, a stored empirical expert model can be used to determine the need for temperature control. As is fundamentally known from the state of the art, time parameters such as the t8/5 time can be used to maintain the material properties. With the help of the method described above, the material properties of the built-up component can be controlled in a targeted manner and material failure can be prevented. The use of tempering fluids allows in-situ cooling at a safe distance from the additive tool during the manufacturing process. The temperature control process is therefore more effective and therefore more resource-saving, especially with regard to the temperature control medium used.
Das Temperierten kann das Verdüsen eines Kühlmediums aufweisen, etwa zur Erzeugung eines Aerosols. Das verdüste Temperiermedium kann einer Fokussierung unterzogen werden, um eine weitere Präzisierung des von dem Temperiermedium beaufschlagten Ortes auf dem Bauteil bzw. auf der aufgebauten Schicht zu erreichen. Beispielsweise kann das Temperiermedium durch eine Düse geleitet werden, die an ihrem Innenumfang eine sich um die Durchlassrichtung der Düse spiralförmig erstreckende Nut aufweist. Bei dem Hindurchleiten des Temperiermediums durch die Düse erfährt das Temperiermedium nur an seinem Außenumfang einen Drall um seine Propagationsrichtung, welcher einer Divergenz des Fluidstrahls entgegenwirkt bzw. zu einer Kompaktierung des Fluidstrahls führt. The tempering can include the atomization of a cooling medium, for example to generate an aerosol. The atomized temperature control medium can be subjected to focusing in order to achieve further precision of the location on the component or on the built-up layer that is acted upon by the temperature control medium. For example, the tempering medium can be passed through a nozzle, which has a groove on its inner circumference that extends spirally around the passage direction of the nozzle. When the temperature control medium is guided through the nozzle, the temperature control medium only experiences a twist about its propagation direction on its outer circumference, which counteracts a divergence of the fluid jet or leads to a compaction of the fluid jet.
Der mindestens eine ortsaufgelöst erfasste Temperaturmesswert und/ oder die Abkühlkurve kann/können gleichzeitig oder nacheinander an unterschiedlichen Orten der Schicht erfasst und aus den erfassten Temperaturmesswerten oder aus den Abkühlkurven können eine Temperaturverteilung und/oder ein Temperaturgradient entlang einer Oberfläche der Schicht ermittelt werden. Mit Hilfe der ortsaufgelösten Bestimmung von Abkühlkurven des aufgebauten Bauteils kann eine sichere lokale Vorhersage der Zugfestigkeit auch bei der additiven Verarbeitung niedrig legierter Stähle erreicht werden. Bei dem ortsselektiven Temperieren kann abhängig von dem ortsaufgelöst erfassten Temperaturmesswert, oder von der Abkühlkurve, oder von einem daraus abgeleiteten Temperaturgradient entlang einer Oberfläche der Schicht ein Volumenstrom des Fluidstrahls eingestellt werden. The at least one spatially resolved measured temperature value and/or the cooling curve can be measured simultaneously or sequentially at different locations in the layer, and a temperature distribution and/or a temperature gradient along a surface of the layer can be determined from the measured temperature values recorded or from the cooling curves. With the help of the spatially resolved determination of cooling curves of the built-up component, a reliable local prediction of the tensile strength can be achieved even with the additive processing of low-alloy steels. In the case of location-selective tempering, a volume flow of the fluid jet can be adjusted along a surface of the layer as a function of the spatially resolved measured temperature value, or of the cooling curve, or of a temperature gradient derived therefrom.
Während des ortsselektiven Temperierens können kontinuierlich oder periodisch weitere Temperaturmesswerte und/oder eine Abkühlkurve an dem temperierten Ort der Schicht erfasst werden. Dabei kann eine Kühl- oder Heizleistung des Fluidstrahls in Bezug auf die Schicht durch Variation eines Volumenstroms des Fluidstrahls abhängig von den weiteren Temperaturmesswerten und/oder der Abkühlkurve in-situ nachgeregelt werden. During the location-selective temperature control, further temperature measurement values and/or a cooling curve at the temperature-controlled location of the layer can be recorded continuously or periodically. A cooling or heating capacity of the fluid jet in relation to the layer can be readjusted in situ by varying a volume flow of the fluid jet as a function of the further measured temperature values and/or the cooling curve.
Zeitgleich kann an mehreren voneinander verschiedenen Orten auf der Schicht der mindestens eine Temperaturmesswert und/oder die Abkühlkurve ermittelt werden. Aus einer Differenz der Temperaturmesswerte benachbarter Orte auf der Schicht und/oder aus der Differenz der Abkühlkurve benachbarter Orte auf der Schicht kann auf einen Wärmestrom innerhalb der Schicht zwischen den Orten geschlossen werden. Bei dem ortsselektiven Temperieren kann eine Kühl- oder Heizleistung des Fluidstrahls auch danach ausgewählt werden, dass der Wärmestrom innerhalb der Schicht bzw. des Bauteils minimiert wird. At the same time, the at least one measured temperature value and/or the cooling curve can be determined at several different locations on the layer. A heat flow within the layer between the locations can be inferred from a difference in the measured temperature values of adjacent locations on the layer and/or from the difference in the cooling curve of adjacent locations on the layer. In the case of location-selective temperature control, a cooling or heating capacity of the fluid jet can also be selected so that the heat flow within the layer or component is minimized.
Das Temperieren kann das ortsselektive Beaufschlagen des Bauteils mit einem Fluidstrahl aufweisen. Dabei kann das Temperieren vorzugsweise weiterhin das Verdüsen eines flüssigen oder festen Temperiermediums aufweisen, wobei vorzugsweise ein das Temperiermedium enthaltenes Aerosol gebildet wird. Beispielsweise kann das Bauteil beziehungsweise die zuletzt aufgebaute Schicht durch Aerosole und/oder einen Flüssigkeits-, Gas- oder Festkörperstrahl gekühlt beziehungsweise erwärmt werden. Dabei kann ein endothermer Phasenübergang von Schwebeteilchen in dem Fluid, beispielsweise in Aerosolpartikeln des Aerosols, erfolgen, zum Beispiel von flüssig nach gasförmig. Zusätzlich kann Wärmeübertragung durch Konduktion von Wärme aus dem Bauteil in Aerosolpartikel erfolgen. The temperature control can include the location-selective impingement of a fluid jet on the component. The temperature control can preferably also include the atomization of a liquid or solid temperature control medium, with an aerosol containing the temperature control medium preferably being formed. For example, the component or the last layer built up can be cooled or heated by aerosols and/or a jet of liquid, gas or solids. In this case, an endothermic phase transition of suspended particles in the fluid, for example in aerosol particles of the aerosol, can take place, for example from liquid to gaseous. In addition, heat transfer can take place by conducting heat from the component into aerosol particles.
Die Temperierung, das heißt die Beaufschlagung des Bauteils beziehungsweise der Schicht mit dem gerichteten Fluidstrahl kann unabhängig von einer Bewegung des additiven Werkzeugs bzw. der Energiequelle während des Aufbauprozesses erfolgen, wodurch ein wirtschaftlicher Vorteil erzielt wird. Demgegenüber sind im Stand der Technik insbesondere globale Kühlungen über Gase oder immersive Flüssigkeitskühlungen des Werkstücks vorgesehen. The temperature control, ie the application of the directed fluid jet to the component or the layer, can take place independently of a movement of the additive tool or the energy source during the construction process, whereby an economic advantage is achieved. In contrast, in the state of Technology in particular global cooling provided by gases or immersive liquid cooling of the workpiece.
Demgemäß kann das Temperieren das ortsselektive Beaufschlagen des Bauteils mit einem Aerosol-, Flüssigkeits,- Gas- oder Festkörperstrahl aufweisen, der einen Materialbestandteil aufweist, der einen endothermen Phasenübergang erfährt und/ oder durch Wärmeleitung erwärmt oder abgekühlt wird, wenn er bei dem Beaufschlagen auf das Bauteil trifft. Accordingly, tempering can include the location-selective impingement of the component with an aerosol, liquid, gas or solid jet that has a material component that undergoes an endothermic phase transition and/or is heated or cooled by thermal conduction when it is impinged on the component hits.
Das Temperieren kann das Ausrichten mindesten eines Temperiermediumauslasses, vorzugsweise einer Düse, einer Temperiermediumquelle auf einen zu kühlenden oder zu erwärmenden Abschnitt des Bauteils aufweisen. Dazu kann die Temperiermediumquelle relativ zu und beabstandet von dem Bauteil sowie unabhängig von einer Energiequelle für das Aufschmelzen des metallischen Zusatzwerkstoffs und/oder unabhängig von dem Sensor bewegt werden. The tempering can include aligning at least one tempering medium outlet, preferably a nozzle, of a tempering medium source to a section of the component that is to be cooled or heated. For this purpose, the tempering medium source can be moved relative to and at a distance from the component and independently of an energy source for melting the metallic filler material and/or independently of the sensor.
Das Temperieren kann das selektive Aktivieren eines oder mehrere einer Vielzahl Temperiermediumauslässe einer Temperiermediumquelle aufweisen, wozu die Vielzahl Temperiermediumauslässe statisch um das Bauteil herum und dem Bauteil zugewandt angeordnet sind. The tempering can include the selective activation of one or more of a plurality of tempering medium outlets of a tempering medium source, for which purpose the plurality of tempering medium outlets are arranged statically around the component and face the component.
Eine Kühlleistung zur Kühlung des Ortes auf der Schicht, an dem mit dem Sensor ortsaufgelöst der Temperaturmesswert erfasst wird, oder eines den Ort umfassenden Abschnitts des Bauteils beziehungsweise eine Heizleistung zur Erwärmung des Ortes oder des Abschnitts des Bauteils kann durch eine Variation des Temperiermediumvolumenstroms, welcher das Bauteil beaufschlagt, erfolgen. Dabei kann der Temperiermediumvolumenstrom derart eingestellt werden, dass die aus den ortsaufgelösten Temperaturwerten abgeleitete Abkühlkurve einer gewünschten Abkühlkurve angenähert wird. A cooling capacity for cooling the location on the layer at which the temperature measurement value is recorded with the sensor in a spatially resolved manner, or a section of the component encompassing the location, or a heating capacity for heating the location or section of the component, can be achieved by varying the temperature control medium volume flow, which Component applied, take place. The temperature control medium volume flow can be set in such a way that the cooling curve derived from the spatially resolved temperature values is approximated to a desired cooling curve.
Das Substrat bzw. das Bauteil kann relativ zu einer feststehenden Energiequelle für das Aufschmelzen des Zusatzwerkstoffs entlang der Trajektorie bewegt werden. Die kinematische Bauteilbewegung kann bei feststehender Energiequelle und vorzugsweise ebenfalls feststehendem Sensor, beispielsweise einem Pyrometer, dazu verwendet werden, ein festes räumliches Verhältnis zwischen der Trajektorie und dem Ort auf der Schicht, an dem die orstaufgelöste Temperaturmessung durchgeführt wird, zu erhalten. Demgemäß kann vorgesehen sein, dass das Substrat beziehungsweise das Bauteil auf einer komplexen Trajektorie unter der Energiequelle bewegt wird. Hierdurch wird ermöglicht, dass mittels des Sensors, beispielsweise eines Pyrometers, unter gleichbleibenden Randbedingungen ortsaufgelöst Abkühlkurven erfasst werden können. Durch eine Verknüpfung der Bewegungsinformationen der Energiequelle mit den ermittelten Abkühlkurven kann eine ortsaufgelöste Gradientenkarte erstellt und aus dieser können die mechanischen Eigenschaften des erzeugten Bauteils ortsaufgelöst ermittelt werden. Es wird somit die Bestimmung der Zugfestigkeitsverteilung eines erzeugten Bauteils über dessen gesamtes Volumen während dessen Erzeugung, mithin in-situ, etwa zum Zwecke der Qualitätssicherung und der Abschätzung der Struktureigenschaften vorgeschlagen. The substrate or the component can be moved along the trajectory relative to a fixed energy source for melting the filler material. With a fixed energy source and preferably also a fixed sensor, for example a pyrometer, the kinematic component movement can be used to obtain a fixed spatial relationship between the trajectory and the location on the layer at which the spatially resolved temperature measurement is carried out. Accordingly, it can be provided that the substrate or the component is moved on a complex trajectory under the energy source. This makes it possible for the sensor, for example a pyrometer, to be able to record spatially resolved cooling curves under constant boundary conditions. By linking the movement information of the energy source with the determined cooling curves, a spatially resolved gradient map can be created and from this the mechanical properties of the component produced can be determined in a spatially resolved manner. It is thus proposed to determine the tensile strength distribution of a component produced over its entire volume during its production, i.e. in-situ, for the purpose of quality assurance and the estimation of the structural properties.
Alternativ kann bei statischer Energiequelle und relativ zu der Energiequelle bewegtem Substrat bzw. Bauteil durch die Verknüpfung der Bewegungsinformation des Bauteils in Bezug auf Energiequelle mit den ermittelten Abkühlkurven eine ortsaufgelöste Gradientenkarte erzeugt und aus dieser können die mechanischen Eigenschaften des Bauteils lokal aufgelöst abgeleitet werden. Alternatively, with a static energy source and a substrate or component moving relative to the energy source, a spatially resolved gradient map can be generated by linking the movement information of the component in relation to the energy source with the determined cooling curves, and from this the mechanical properties of the component can be derived locally resolved.
Das Substrat kann weiterhin relativ zu mindestens einem feststehenden Sensor für die ortsaufgelöste Erfassung mindestens einer Eigenschaft, vorzugsweise einer Temperatur, einer zuletzt aufgebauten Schicht des Bauteils entlang der Trajektorie bewegt werden. The substrate can also be moved along the trajectory relative to at least one stationary sensor for the spatially resolved detection of at least one property, preferably a temperature, of a layer of the component that was last built up.
Der Sensor kann bei einer festen relativen Anordnung zu der Energiequelle gehalten werden, vorzugsweise unter einem festen, spitzen Winkel und/ oder zu der Energiequelle, wobei das Substrat in Bezug auf die Energiequelle und den Sensor unter Beibehaltung der festen relativen Anordnung zwischen der Energiequelle und dem Sensor entlang der Trajektorie bewegt wird. The sensor may be maintained at a fixed relative disposition to the energy source, preferably at a fixed, acute angle and/or to the energy source, with the substrate relative to the energy source and the sensor while maintaining the fixed relative disposition between the energy source and the Sensor is moved along the trajectory.
Das Verfahren kann weiterhin das punktuelle Erfassen mindestens eines Messwerts, etwa des Temperaturmesswerts, an mindestens einem Messpunkt auf der zuletzt aufgebauten Schicht mit dem Sensor aufweisen. Dabei werden vorzugsweise für mehrere Messwert-Messpunkt-Paare dieselbe relative Anordnung zwischen dem jeweiligen Messpunkt auf der Schicht und einem jeweiligen Schmelzbad des Zusatzwerkstoffs für den Aufbau der Schicht eingehalten. Beispielsweise kann dazu der Sensor in Bezug auf eine Energiequelle fest angeordnet sein und dazu vorzugsweise denselben Vorschub entlang der Trajektorie wie die Energiequelle aufweisen. Eine Vielzahl der Messwerte kann an einer entsprechenden Vielzahl Messpunkte auf dem aufgebauten Bauteil erfasst werden, wobei vorzugsweise je Messpunkt jeweils mindestens ein Messwert erfasst wird. Aus der Vielzahl Messwerte kann eine ortsaufgelöste Messwertkurve entlang der Trajektorie, beispielsweise mittels einer Regressionsanalyse, erzeugt werden. The method can also include the selective detection of at least one measured value, for example the temperature measured value, at at least one measuring point on the last layer built up with the sensor. In this case, the same relative arrangement between the respective measuring point on the layer and a respective molten pool of the additional material for the structure of the layer is preferably maintained for several pairs of measured value and measuring points. For example, the sensor can be fixed in relation to an energy source and can preferably have the same feed along the trajectory as the energy source. A large number of measured values can be recorded at a corresponding large number of measuring points on the built-up component, with at least one measured value preferably being recorded for each measuring point. A spatially resolved measured value curve along the trajectory can be generated from the large number of measured values, for example by means of a regression analysis.
Mit dem Sensor kann die Temperatur des aufgebauten Bauteils an mindestens einem Messpunkt auf dem aufgebauten Bauteil erfasst werden. Dabei kann aus der Temperatur an dem Messpunkt, einem Abstand des Messpunkts zu einem Schmelzbad entlang der Trajektorie sowie einer Vorschubgeschwindigkeit der Energiequelle entlang der Trajektorie ein Temperaturgradient entlang der Trajektorie bestimmt werden. With the sensor, the temperature of the built-up component can be recorded at at least one measuring point on the built-up component. A temperature gradient along the trajectory can be determined from the temperature at the measuring point, a distance from the measuring point to a melt pool along the trajectory and a feed rate of the energy source along the trajectory.
Der für den Sensor bei dem Ermitteln des Messwerts kann ein Sensor für die gerichtete, berührungslose Temperaturmessung, beispielsweise ein Pyrometer, verwendet werden, mit dem eine ortsaufgelöste Abkühlkurve der zuletzt aufgebauten Schicht des Bauteils ermittelt wird. A sensor for the directed, non-contact temperature measurement, for example a pyrometer, can be used for the sensor when determining the measured value, with which a spatially resolved cooling curve of the last built-up layer of the component is determined.
Das Verfahren kann weiterhin das Manipulieren der Trajektorie und/oder mindestens eines Prozessparameters für das Aufschmelzen des Zusatzwerkstoffs und/oder für das schichtweise Aufbauen des Bauteils aufweisen. Das Manipulieren kann dazu eingerichtet sein, die ermittelte Abkühlkurve einer bevorzugten Abkühlkurve anzugleichen oder weiter anzunähern, um eine bevorzugte Materialeigenschaft einzustellen. The method can also include manipulating the trajectory and/or at least one process parameter for melting the additional material and/or for building up the component in layers. The manipulation can be set up to match or further approximate the determined cooling curve to a preferred cooling curve in order to set a preferred material property.
An einer Vielzahl Messpunkte auf der zuletzt aufgebauten Schicht und/oder auf einer Mehrzahl nacheinander aufeinander aufgebauter Schichten kann jeweils eine ortsaufgelöste Abkühlkurve ermittelt werden. Dabei kann aus den ermittelten ortsaufgelösten Abkühlkurven eine ortsaufgelöste Abkühlgradientenkarte der Schicht beziehungsweise des Bauteils bestimmt und mindestens eine mechanische Eigenschaft der zuletzt aufgebauten Schicht beziehungsweise des Bauteils lokal aufgelöst bestimmt werden. A spatially resolved cooling curve can be determined at a large number of measurement points on the last layer built up and/or on a plurality of layers built up one after the other. A spatially resolved cooling gradient map of the layer or component can be determined from the determined spatially resolved cooling curves and at least one mechanical property of the last layer or component built up can be determined in a locally resolved manner.
Weitere Einzelheiten der Erfindung werden anhand der nachstehenden Figuren erläutert. Dabei zeigt: Fig. i eine schematische Darstellung eines erfindungsgemäßen Verfahrens gemäß einer ersten Ausführungsform; Further details of the invention are explained with reference to the figures below. It shows: 1 shows a schematic representation of a method according to the invention according to a first embodiment;
Fig.2 eine schematische Darstellung eines erfindungsgemäßen Verfahrens gemäß einer zweiten Ausführungsform; 2 shows a schematic representation of a method according to the invention according to a second embodiment;
Fig. 3 eine Detailansicht einer bespielhaften Vorrichtung zur Durchführung eines erfindungsgemäßen Verfahrens; 3 shows a detailed view of an exemplary device for carrying out a method according to the invention;
Fig. 4 ein Messpunktraster eines Sensors für die ortsselektive Erfassung von Temperaturmesswerten; 4 shows a measuring point grid of a sensor for the location-selective detection of measured temperature values;
Fig. 5 eine Abkühlgradientenkarte, die aus entlang eines Rasters nach Fig. 4 erfassten Temperaturmesswerten abgeleitet worden ist; und FIG. 5 is a cooling gradient map derived from temperature readings taken along a grid of FIG. 4; and
Fig. 6 eine anhand der Abkühlgradientenkarte gemäß Fig. 5 abgeleitete resultierende Verformung eines generativ gefertigten Bauteils. FIG. 6 shows a resulting deformation of an additively manufactured component derived using the cooling gradient map according to FIG.
Die Fig. 1 veranschaulicht in schematischer Darstellung eine erste Ausführungsform eines erfindungsgemäßen Verfahrens für die generative Fertigung von Bauteilen. Mit Hilfe einer Energiequelle 10 wird lokal auf einem Substrat 3 beziehungsweise auf einer auf dem Substrat zuvor aufgebrachten Werkstoffschicht ein Schmelzbad eines Zusatzwerkstoffs 1 erzeugt. Die Energiequelle 10 und eine Zusatzwerkstoffzufuhr (nicht dargestellt) werden entlang der Trajektorie 2 bewegt, um das Bauteil schichtweise beispielsweise entsprechend einer zuvor erzeugten CAD-Konstruktion aufzubauen. Alternativ können die Energiequelle 10 und die Zusatzwerkstoffzufuhr (nicht dargestellt) auch statisch und unter einer definierten Ausrichtung zueinander angeordnet sein und das Bauteil, mithin das Substrat 3, relativ zu der Energiequelle 10 und der Zusatzwerkstoffzufuhr bewegt werden. Dabei kann das Substrat 3 beziehungsweise das Bauteil 4 auf einer komplexen Trajektorie 2 unter der Energiequelle 10 bewegt werden. Hierdurch wird es ermöglicht, mittels eines Sensors 5, beispielsweise eines Pyrometers, unter gleichbleibenden Randbedingungen ortsaufgelöst Abkühlkurven zu erfassen. 1 illustrates in a schematic representation a first embodiment of a method according to the invention for the additive manufacturing of components. With the aid of an energy source 10, a molten bath of an additional material 1 is produced locally on a substrate 3 or on a material layer previously applied to the substrate. The energy source 10 and an additional material feed (not shown) are moved along the trajectory 2 in order to build up the component in layers, for example in accordance with a previously generated CAD design. Alternatively, the energy source 10 and the filler material supply (not shown) can also be arranged statically and with a defined alignment to one another and the component, and therefore the substrate 3, can be moved relative to the energy source 10 and the filler material supply. In this case, the substrate 3 or the component 4 can be moved on a complex trajectory 2 under the energy source 10 . This makes it possible to use a sensor 5, for example a pyrometer, to detect spatially resolved cooling curves under constant boundary conditions.
Der gesamte Aufbauprozess wird mit einem Sensor 5 erfasst, der vorliegend als ein Pyrometer oder eine Wärmebildkamera ausgebildet ist. Das Pyrometer beziehungsweise die Wärmebildkamera ist dazu eingerichtet, ortsaufgelöst die Temperatur des Bauteils 4, zumindest jedoch der zuletzt aufgebauten Schicht des Bauteils 4 zu erfassen, um abhängig von der erfassten Temperaturverteilung beziehungsweise von ortsselektiv erfasster Abkühlkurven eine ortsselektive Temperierung der Schicht beziehungsweise des Bauteils 3 zu ermöglichen. Die Temperierung, insbesondere die Kühlung des Bauteils beziehungsweise der zuletzt aufgebrachten Schicht kann dazu eingerichtet sein, die mit Hilfe des Sensors 5 erfasste tatsächliche Abkühlkurve der Schicht beziehungsweise des Bauteils 3 einer in Bezug auf angestrebte Materialeigenschaften bevorzugte Abkühlkurve anzunähern. Alternativ oder zusätzlich kann angestrebt werden, die Abkühlkurven über das gesamte Bauteil hinweg einander anzunähern, sodass homogene Materialeigenschaften über den gesamten Bauteilkorpus erreicht werden. Beispielsweise kann abhängig von dem lokalen Oberflächen-Volumen-Verhältnis die natürliche Abkühlung durch freie Konvektion und Wärmestrahlung an die Umgebungsluft über das Volumen des Bauteils variieren, sodass durch gezielten Temperiereingriff die Abkühlkurven über den gesamten Bauteilkorpus hinweg einander angenähert werden können. The entire construction process is recorded with a sensor 5, which is embodied in the present case as a pyrometer or a thermal imaging camera. The pyrometer or the thermal imaging camera is set up to spatially resolved the To detect the temperature of the component 4, but at least the last built-up layer of the component 4, in order to enable a location-selective temperature control of the layer or of the component 3 depending on the detected temperature distribution or on location-selectively detected cooling curves. The temperature control, in particular the cooling of the component or the layer applied last, can be set up to approximate the actual cooling curve of the layer or of the component 3 detected with the aid of the sensor 5 to a preferred cooling curve in relation to the desired material properties. Alternatively or additionally, the aim can be to bring the cooling curves closer together over the entire component, so that homogeneous material properties are achieved over the entire body of the component. For example, depending on the local surface-volume ratio, the natural cooling through free convection and thermal radiation to the ambient air can vary over the volume of the component, so that the cooling curves can be brought closer together over the entire body of the component through targeted temperature control intervention.
Für die Temperierung der Schicht beziehungsweise des Bauteils 3 ist mindestens eine Temperiermediumquelle 9 vorgesehen, die beispielsweise über einen Temperiermediumauslass 8, etwa eine Düse, eine temperierbedürftige Stelle auf dem Bauteil 3 mit einem gerichteten Fluidstrahl 6 beaufschlagen kann. Der gerichtete Fluidstrahl 6 kann als Temperiermedium 7 beispielsweise ein Aerosol aufweisen. Alternative Temperiermedien können Öle oder Ölemulsionen zur Anpassung des Siedepunkts des Temperiermediums aufweisen. Darüber hinaus können die Öle oder Ölemulsionen einen Korrosionsschutz für das Bauteil 4 darstellen. Zur Stabilisierung des Lichtbogens kann das Kühlmedium beispielsweise eine Kaliumlösung aufweisen, sodass das Temperiermedium neben seiner Temperiereigenschaft weiterhin zur Stabilisierung des Lichtbogens verwendet werden kann. Durch die Verwendung von Flussmitteln als Kühlmedium können Oxide auf der Schicht entfernt beziehungsweise der Einbrand geändert werden. Darüber hinaus ist die Verwendung anderer chemischer Additive denkbar, welche zu einer Änderung der Legierungszusammensetzung beim Überschweißen führen. At least one temperature control medium source 9 is provided for temperature control of the layer or of the component 3, which can apply a directed fluid jet 6 to a point on the component 3 that requires temperature control, for example via a temperature control medium outlet 8, such as a nozzle. The directed fluid jet 6 can have an aerosol, for example, as the temperature control medium 7 . Alternative tempering media can include oils or oil emulsions to adjust the boiling point of the tempering medium. In addition, the oils or oil emulsions can protect the component 4 against corrosion. To stabilize the arc, the cooling medium can contain a potassium solution, for example, so that the temperature control medium can continue to be used to stabilize the arc in addition to its temperature control property. By using flux as a cooling medium, oxides on the layer can be removed or the penetration can be changed. In addition, the use of other chemical additives is conceivable, which lead to a change in the alloy composition when overwelding.
Bei der Verwendung eines Aerosols zur Temperierung, insbesondere zur Kühlung des Bauteils kann darauf abgezielt werden, die Verdampfungstemperatur zu erhöhen, damit die in dem Aerosol enthaltene Flüssigkeit näher an die Prozesszone herankommt und damit eine effektivere Wärmeübertragung von dem Bauteil an das Aerosol über die Verdampfungsenthalpie erreicht wird. Hierbei können beispielsweise Öl-Wasser- Emulsionen als Flüssigkeiten des Aerosols verwendet werden. Auch die Verwendung von Gasen kann aufgrund ihrer Wärmekapazität und Wärmeleitfähigkeit dann vorteilhaft sein, wenn in unmittelbarer Nähe zum Schmelzbad temperiert, insbesondere gekühlt werden soll. Zur Vermeidung von Poren hat sich insbesondere die Verwendung Inertgasen als zweckmäßig herausgestellt. Bei der Temperierung verdampfendes Kühlmedium kann mit Hilfe einer Temperiermediumrückgewinnung 11 aufgenommen und nach einer Kondensierung für die Wiederverwendung in die Temperiermediumquellen 9 rezirkuliert werden. When using an aerosol for temperature control, in particular for cooling the component, the aim can be to increase the vaporization temperature so that the liquid contained in the aerosol comes closer to the process zone and thus achieves more effective heat transfer from the component to the aerosol via the vaporization enthalpy becomes. Here, for example, oil-water Emulsions are used as liquids of the aerosol. Due to their heat capacity and thermal conductivity, the use of gases can also be advantageous if temperature control, in particular cooling, is to be carried out in the immediate vicinity of the molten bath. To avoid pores, the use of inert gases has proven to be particularly useful. Cooling medium evaporating during temperature control can be taken up with the aid of a temperature control medium recovery system 11 and, after condensation, can be recirculated to the temperature control medium sources 9 for reuse.
Es kann inbesondere vorgesehen sein, dass das Substrat 3 relativ zu der Energiequelle 10 entlang der Trajektorie 2 bewegt wird, während die Energiequelle 10 feststehend ausgebildet ist. Auf diese Weise kann ein festes Verhältnis zwischen der Schweißtrajektorie 2 und einem Temperaturmesspunkt des Sensors 5 auf dem Bauteil 3 erreicht werden. Hierdurch können mittels des Sensors 5, der beispielsweise ein Pyrometer sein kann, unter gleichbleibenden Randbedingungen Abkühlkurven gemessen werden. Ein Machine-Learning-Algorithmus auf Basis eines vortrainierten neuronalen Netzes kann dazu verwendet werden, um aus den erfassten Informationen eine Abkühlkurve für einen werkstofflich relevanten Bereich des Bauteils 3 zu bestimmen. Durch die Verknüpfung der Bewegungsinformation des Bauteils unter der Energiequelle 10 mit den ermittelten Abkühlkurven kann eine ortsaufgelöste Gradientenkarte erzeugt und aus dieser können die mechanischen Eigenschaften des Bauteils lokal aufgelöst abgeleitet werden. In particular, it can be provided that the substrate 3 is moved relative to the energy source 10 along the trajectory 2, while the energy source 10 is stationary. In this way, a fixed relationship between the welding trajectory 2 and a temperature measuring point of the sensor 5 on the component 3 can be achieved. As a result, cooling curves can be measured under constant boundary conditions by means of the sensor 5, which can be a pyrometer, for example. A machine learning algorithm based on a pre-trained neural network can be used to determine a cooling curve for a materially relevant area of the component 3 from the recorded information. By linking the movement information of the component under the energy source 10 with the determined cooling curves, a spatially resolved gradient map can be generated and from this the mechanical properties of the component can be derived in a locally resolved manner.
Die Fig. 2 zeigt eine weitere Ausführungsform eines erfindungsgemäßen Verfahrens, bei dem abweichend von der Ausführungsform gemäß Fig. 1 die Temperiermediumquellen 9 statisch angeordnet und entsprechend eines ermittelten Temperierbedarfs angesteuert werden, um die Schicht ortsselektiv mit einem gerichteten Fluidstrahl 6 zu temperieren. Dazu kann einerseits vorgesehen sein, dass die Temperiermediumquellen 9 selektiv angesteuert werden und andererseits das Bauteil 3 beispielsweise von einem Knickarmroboter derart in Bezug auf mindestens eine der Temperiermediumquellen 9 bewegt werden, dass der Auslass 8 der Temperiermediumquelle 9 exakt einer temperierbedürftigen Stelle der zuletzt aufgebauten Schicht oder des Bauteils 3 zugewandt ist, sodass eine hochgenau ortsselektive Beaufschlagung des Bauteils beziehungsweise der Schicht mit dem gerichteten Fluidstrahl 6 möglich ist. Die Fig. 3 zeigt eine Detailansicht eines bespielhaften Aufbaus zur Durchführung des erfindungsgemäßen Verfahrens. In Schweißrichtung einer Energiequelle 10, beispielsweise eines Lichtbogen- oder eines Plasma-Lichtbogen-Schweißbrenners ist eine Temperiermediumquelle 9 angeordnet. Dabei ist die Temperiermediumquelle 9 unter einem spitzen Winkel zu der Energiequelle 10 dem Substrat 3 zugewandt und entgegen der Schweißrichtung ausgerichtet. Die Energiequelle 10 sowie die Temperiermediumquelle 9 sind unter einem starren Verhältnis zueinander angeordnet, insbesondere unter einem festen Winkel und einem festen Abstand zueinander. Beispielsweise können die Energiequelle 10 und die Temperiermediumquelle 9 an einem Endeffektor eines Knickarmrobotors fest zueinander angeordnet positioniert sein. Aufgrund der festen Anordnung der Temperiermediumquelle 9 in Bezug auf die Energiequelle 10 erfolgt die Beaufschlagung der zuletzt aufgebrachten Schicht beziehungsweise des Bauteils mit dem aus der Temperiermediumquelle 9 austretenden Temperiermedium bei gegebener Vorschubgeschwindigkeit der Anordnung aus Energiequelle 10 und Temperiermediumquelle 9 in Schweißrichtung unter einem konstanten zeitlichen Abstand, sodass prozesssicher die Beeinflussung der Temperatur der Schmelze beziehungsweise des erstarrenden Werkstoffs durch die Beaufschlagung der Temperiermediumquelle 9 eingestellt werden kann. Dies ermöglicht die präzise Beeinflussung der Abkühlkurve des aufgebrachten Materials und damit der Materialeigenschaften des Werkstoffs. 2 shows a further embodiment of a method according to the invention, in which, in contrast to the embodiment according to FIG. For this purpose, provision can be made on the one hand for the temperature control medium sources 9 to be controlled selectively and on the other hand for the component 3 to be moved, for example by an articulated-arm robot, in relation to at least one of the temperature control medium sources 9 in such a way that the outlet 8 of the temperature control medium source 9 is located exactly at a point in the last built-up layer that requires temperature control or of the component 3 is facing, so that a highly precise location-selective impingement of the component or the layer with the directed fluid jet 6 is possible. FIG. 3 shows a detailed view of an exemplary structure for carrying out the method according to the invention. A tempering medium source 9 is arranged in the welding direction of an energy source 10, for example an arc or a plasma arc welding torch. The tempering medium source 9 faces the substrate 3 at an acute angle to the energy source 10 and is aligned opposite to the welding direction. The energy source 10 and the tempering medium source 9 are arranged in a rigid relationship to one another, in particular at a fixed angle and at a fixed distance from one another. For example, the energy source 10 and the temperature control medium source 9 can be positioned fixed to one another on an end effector of an articulated arm robot. Due to the fixed arrangement of the tempering medium source 9 in relation to the energy source 10, the last applied layer or the component is acted upon by the tempering medium emerging from the tempering medium source 9 at a given feed rate of the arrangement of the energy source 10 and the tempering medium source 9 in the welding direction at a constant time interval, so that the influencing of the temperature of the melt or the solidifying material can be adjusted in a process-reliable manner by applying the temperature control medium source 9 . This enables the precise influencing of the cooling curve of the applied material and thus the material properties of the material.
Die Fig. 4 bis 6 veranschaulichen einerseits ein Messraster, welches beispielsweise dasjenige eines Pyrometers sein kann, das als Sensor über die ortsaufgelöste Temperaturmessung auf der Oberfläche des aufgebrachten Bauteils, insbesondere einer zuletzt aufgebrachten Schicht verwendet werden kann. Mit Hilfe des Sensors kann entlang der Rasterpunkte kontinuierlich oder periodisch ein Temperaturmesswert erfasst werden, sodass an einem gegebenen Ort auf dem Bauteil beziehungsweise der zuletzt aufgebrachten Schicht aus einer Mehrzahl der einem jeweiligen Rasterpunkt zeitlich hintereinander erfassten Temperaturwerte einer Abkühlkurve bestimmt werden kann, aus welcher sich Rückschlüsse auf eine Materialeigenschaft des aufgebauten Werkstoffs ableiten lassen. Neben der Zugfestigkeit können sich auch Verspannungen innerhalb des Materials anhand einer aus den erfassten Abkühlkurven ermittelten Abkühlgradientenkarte gemäß Fig. 5 ableiten. Beispielsweise kann bei großvolumigen Bauteilen aufgrund der stärkeren Abkühlung im Oberflächenbereich des Bauteils im vergleich zur weiter im Inneren des Bauteils liegenden Bereichen anhand der sich daraus in der Abkühlgradientenkarte ergebenen Abweichungen der Abkühlgradienten eine mechanische Verspannung des Bauteils ermittelt werden. Ebenso können aus der Abkühlgradientenkarte Zugfestigkeitswerte über das Volumen des Bauteils verteilt ermittelt werden. 4 to 6 illustrate on the one hand a measuring grid, which can be that of a pyrometer, for example, which can be used as a sensor for the spatially resolved temperature measurement on the surface of the applied component, in particular a layer applied last. With the help of the sensor, a temperature measurement value can be recorded continuously or periodically along the grid points, so that at a given location on the component or the last applied layer, a cooling curve can be determined from a plurality of temperature values recorded in chronological succession at a respective grid point, from which conclusions can be drawn can be derived from a material property of the constructed material. In addition to the tensile strength, stresses within the material can also be derived using a cooling gradient map according to FIG. 5 determined from the recorded cooling curves. For example, in the case of large-volume components, mechanical stressing of the component can be determined on the basis of the deviations in the cooling gradients resulting from the deviations in the cooling gradient map due to the stronger cooling in the surface area of the component compared to the areas further inside the component. Tensile strength values distributed over the volume of the component can also be determined from the cooling gradient map.
Die in der vorstehenden Beschreibung, in den Zeichnungen sowie in den Ansprüchen offenbarten Merkmale der Erfindung können sowohl einzeln als auch in beliebiger Kombination für die Verwirklichung der Erfindung wesentlich sein. The features of the invention disclosed in the above description, in the drawings and in the claims can be essential for the realization of the invention both individually and in any combination.
Bezugszeichenliste: Reference list:
Zusatzwerkstoff filler material
Trajektorie trajectory
Substrat substrate
Bauteil component
Sensor sensor
Fluidstrahl fluid jet
Temperiermediumtempering medium
TemperiermediumauslassTempering medium outlet
Temperiermediumquelle Tempering medium source
Energiequelle energy source
Temperiermediumrückgewinnung Tempering medium recovery
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DE102021101846.3A DE102021101846A1 (en) | 2021-01-27 | 2021-01-27 | PROCESSES FOR THE ADDITIONAL MANUFACTURING OF COMPONENTS |
PCT/DE2021/101000 WO2022161566A1 (en) | 2021-01-27 | 2021-12-14 | Method for the additive manufacturing of components with locally selective temperature control |
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EP4284579A1 true EP4284579A1 (en) | 2023-12-06 |
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US (1) | US20240033827A1 (en) |
EP (1) | EP4284579A1 (en) |
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DE102014203711A1 (en) | 2014-02-28 | 2015-09-03 | MTU Aero Engines AG | Generation of residual compressive stresses in generative production |
GB2527375A (en) * | 2014-06-20 | 2015-12-23 | Linde Ag | Welding apparatus |
DE102015108131A1 (en) | 2015-05-22 | 2016-11-24 | GEFERTEC GmbH | Method and apparatus for additive manufacturing |
DE102015117238A1 (en) | 2015-10-09 | 2017-04-13 | GEFERTEC GmbH | Machining module for an additive manufacturing device |
DE102015122135A1 (en) * | 2015-12-17 | 2017-06-22 | GEFERTEC GmbH | Method and apparatus for the additive production of a shaped article by means of build-up welding |
DE102015122889B3 (en) | 2015-12-29 | 2017-01-12 | Rheinisch-Westfälische Technische Hochschule Aachen | Method and measuring arrangement for determining the tensile strength of a welded material |
DE102017005426A1 (en) | 2017-06-11 | 2018-12-13 | Christian Schmid | Machine and process for additive and subtractive production in one clamping |
DE102017216704A1 (en) | 2017-09-21 | 2019-03-21 | Siemens Aktiengesellschaft | Method and device for the additive production of a component |
US11009863B2 (en) | 2018-06-14 | 2021-05-18 | Honeywell International Inc. | System and method for additive manufacturing process monitoring |
US20200130268A1 (en) | 2018-10-29 | 2020-04-30 | Hamilton Sundstrand Corporation | Enhanced cooling during additive manufacturing |
US11897030B2 (en) * | 2020-07-08 | 2024-02-13 | Air Products And Chemicals, Inc. | Method and system for improved temperature control for additive manufacturing |
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- 2021-12-14 US US18/265,391 patent/US20240033827A1/en active Pending
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